JP2006300323A - Rolling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling device especially for working at a high speed which effectively suppresses the deterioration of the accuracy of repeated positioning by the thermal expansion of a supporting body and the wear of a rolling body, can be stably used for a long period of time and can improve the strength of the supporting body to bending moment and suppress the wear of the rolling body while maintaining the high stiffness of the supporting body. <P>SOLUTION: A rolling device wherein at least one of a movable element, a supporting body and a rolling body is formed of one material of a ceramic material, cermet, and cemented carbide with the ratio of bending strength to a density of 1.2×10<SP>7</SP>mm or more, a guide rail 13 as the supporting body or the movable element is formed of the ceramic material with the ratio of the bending strength to the density of 1.2×10<SP>7</SP>mm or more and comprises a flat surface with a surface roughness of 0.5 μmRa or less. As for the guide rail 13, the corner 18a of a cutout part 18 for avoiding interference with a mounting member has a radius of curvature of 0.1 mm or more. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to rolling devices such as rolling bearings, linear motion guide devices, and ball screws, and in particular, high speed, corrosion such as various spindles, various pumps, semiconductor manufacturing devices (conveying devices, etc.), machine tools, turbines, and the like. The present invention relates to a rolling device that can be used under a high load in an environment, a high-temperature environment, or an environment that supports a radial load.

  An electronic component mounting apparatus used in a process of manufacturing an electronic device such as a computer or a mobile phone is provided with an electronic component suction head that can move up and down, for example, above an XY table on which a substrate is placed. The electronic component is adsorbed and mounted on a predetermined position of the substrate. Therefore, in order to accurately mount the electronic component at a predetermined position on the board with such an electronic component mounting apparatus, the head lifting mechanism for improving the positioning accuracy of the XY table and reciprocating the electronic component suction head in the vertical direction is provided. It is necessary to improve the positioning accuracy. To that end, it is necessary to increase the positioning accuracy of the linear motion guide device used as the linear guide of the head lifting mechanism.

In particular, with recent miniaturization of electronic equipment itself, the miniaturization of electronic components mounted on a substrate and the high integration of the substrate have progressed, and positioning accuracy when mounting electronic components has reached the order of several μm. For this reason, the positioning accuracy required for the linear motion guide device has also been increasing.
Also, in order to increase production efficiency, the mounting speed tends to increase. For example, in order to enable mounting of electronic components at such a speed that one cycle is 0.5 to 0.1 seconds or less, an electronic component suction head is required. A head elevating mechanism that can be moved up and down at high speed is required. For this purpose, the linear motion guide device incorporated in the head elevating mechanism must be able to cope with the reciprocating motion of the head at high speed. These requirements can be applied not only to the linear motion guide device used for the head lifting mechanism described above, but also to the linear motion guide device used for the bonding head lifting mechanism of the wire bonding apparatus, for example.

  By the way, in order to move the electronic component suction head of the electronic component mounting device and the bonding head of the wire bonding device up and down with high accuracy and high speed, the guide rail of the linear motion guide device is made to have high rigidity and the deflection or vibration generated in the guide rail. As such a linear motion guide device in which the rigidity of the guide rail is increased, one disclosed in, for example, Japanese Patent Application Laid-Open No. Sho 62-175691 (Japanese Patent Publication No. 6-44051) is disclosed. Are known. Japanese Patent Application Laid-Open No. 11-62958 discloses a technique of using a cemented carbide as a rail material of a guide rail.

However, the linear motion guide device disclosed in Japanese Patent Application Laid-Open No. 62-175691 is a guide rail formed of a ceramic material having a specific rigidity of 0.8 × 10 ⁸ mm or more, and is used for an electronic component mounting device or a wire. Application to a bonding apparatus or the like has been difficult for the following reasons.
That is, in many electronic component mounting apparatuses and wire bonding apparatuses, the slider of the linear motion guide device is fixed to a support base or the like, and the head is reciprocated by moving the guide rail. On the other hand, the linear motion guide device disclosed in the above publication is configured to be used by fixing both ends of the guide rail to a support base and the like and moving the slider. And is not suitable for wire bonding equipment.

  In addition, since many electronic component mounting devices perform a series of processes from adsorption to mounting of electronic components in succession, multiple guide rails are provided on a rotating drum to mount electronic components continuously. The so-called machine gun method is adopted. For this reason, in addition to the vertical movement for mounting electronic components, rotation acceleration due to the rotation of the drum synchronized with this is applied to the guide rail, so inertial force generated by the rail's own weight, head weight, etc. is bent on the guide rail. Acts as a moment. In particular, when the cycle time of the vertical movement of the guide rail exceeds 0.2 seconds, the acceleration applied to the guide rail becomes several G to several tens G, and in addition to this, the acceleration in the circumferential direction of the drum Is about several G. Therefore, the guide rail used under such conditions is required to have sufficient strength against the above-described compound acceleration, the rail weight and the inertial force generated by the head mass.

  However, although the ceramic guide rail disclosed in the above publication is high in hardness and rigidity, it is not so high in bending strength and is bent in comparison with a guide rail made of a steel material such as bearing steel or stainless steel. Low strength. Further, when a large bending moment is applied to the guide rail, the guide rail may be damaged if the bending strength is insufficient even if the constituent material of the guide rail is alumina ceramics, silicon carbide ceramics, silicon nitride, or the like. Therefore, as in the technique disclosed in the above publication, it is difficult to increase the speed of the apparatus from the viewpoint of strength reliability (particularly reliability with respect to bending strength) simply by making the guide rail ceramic.

  In addition, guide rails made of brittle materials such as ceramics are sensitive to changes in strength (stress concentration) due to the rail shape, and are cut to avoid interference with mounting holes for mounting parts such as the head. When a notch or the like is provided on the guide rail, stress concentration tends to occur at that portion. For this reason, if the guide rail is simply made into ceramic, it is difficult to increase the speed of the apparatus due to the strength reliability (particularly with respect to bending strength).

  Furthermore, by using a ceramic material for the rail material, the rail itself is highly rigid, but the contact surface pressure with the rolling element incorporated in the slider increases, so that the rolling element load uses a steel rail. It becomes larger than the case. For example, if silicon nitride is used as the rail material and the rolling element is made of martensitic stainless steel, the difference between the two is more than twice, and the rolling element is compared with the case where the steel rail is used. Wear may be accelerated.

  On the other hand, as disclosed in JP-A-11-62958, materials having high rigidity, that is, materials having a high Young's modulus as material properties include cermet and cemented carbide. Cermet and cemented carbide have a very high Young's modulus of about 300 GPa to 650 GPa compared to metal materials such as bearing steel (250 GPa), and various ceramics (silicon nitride: about 250 GPa to 350 GPa, alumina: 350 GPa to 420 GPa). Higher than silicon carbide: about 400 GPa to 420 GPa). Therefore, if the guide rail is formed of cermet or cemented carbide having a high Young's modulus, the guide rail can be made highly rigid. However, when the guide rail rotates while moving up and down at a high speed, such as an electronic component mounting device or a wire bonding device, a large inertia force is generated due to the acceleration, the weight of the rail, and the head weight. (Cycle speed, response performance) deteriorates. In this case, if the density (mass) of the guide rail is large, the inertial force also increases. Therefore, even when cermet or cemented carbide is used as the rail material, the bending strength of the guide rail becomes insufficient, which may lead to damage. is there.

  Further, when a ceramic material (especially normal silicon nitride) is used as a rail material, the thermal conductivity is low, and heat is easily accumulated inside the apparatus. In other words, if the guide rail is formed of a ceramic material with poor thermal conductivity such as silicon nitride, the sliding surface temperature of the guide rail is higher during operation than when a steel material such as bearing steel is used as the rail material. Therefore, since the grease viscosity decreases due to the temperature rise of the rail sliding surface, the formation of an oil film between the rolling element and the rail groove surface is hindered, which causes rolling element wear and microseizure. These cause vibration when the linear motion guide device is operated, and adversely affect the positioning accuracy repeatedly. In addition, the temperature rise of the rail material promotes the thermal expansion of the guide rail, which repeatedly adversely affects the positioning accuracy.

  Furthermore, in order to obtain stable repeat positioning accuracy over a long period of time, a rail material with good heat dissipation is required. In particular, the operating conditions of the linear motion guide device are becoming faster, and in addition to this, the requirement for repeated positioning accuracy is becoming stricter. In order to satisfy these requirements, there is little misalignment due to the elastic deformation of the rail material, and the heat dissipation of the device is improved to prevent thermal expansion and rolling element wear, ensuring long-term positioning accuracy. Such a linear motion guide device is required.

  By the way, since various chemicals are used in the cleaning process and the film-forming process when manufacturing semiconductors, liquid crystal panels, hard disks, etc., the rolling device used in these processes has a chemical atmosphere. It is required to operate without problems even in corrosive environments. In addition, because of the large diameter of wafers and liquid crystal panels, it has become necessary for the rolling device to support a larger load.

Japanese Patent Application Laid-Open No. 8-121488 discloses a corrosion-resistant rolling bearing in which an outer ring is made of a ceramic material manufactured by an atmospheric pressure sintering method and an inner ring is made of a ceramic material manufactured by a gas pressure sintering method or an HIP method. ing.
Japanese Laid-Open Patent Publication No. 10-82426 discloses a ceramic rolling bearing having excellent corrosion resistance in which an inner ring, an outer ring, and a rolling element are made of silicon carbide.

On the other hand, in jet engines and gas turbines, efficiency is being promoted from the viewpoint of energy saving and environmental problems, so the rolling devices used for these should operate without problems even under higher loads and temperatures. Is required.
However, the rolling bearing described in the above-mentioned Japanese Patent Application Laid-Open No. 8-121488 has the following problems because the outer ring is manufactured by the atmospheric pressure sintering method. That is, a member manufactured by the normal pressure sintering method has low strength and fracture toughness, and microcracks are likely to propagate from the surface and internal defects. Therefore, a large amount of wear powder is generated or cracks occur, and the rolling bearing may have a short life.

In particular, when a rolling bearing supports a radial load, the load concentrates in the outer ring load zone, so cracks easily propagate in the outer ring load zone manufactured by atmospheric pressure sintering even under light loads. The life may be extremely short.
Further, when the inner ring, the outer ring, and the rolling element are made of silicon carbide as in the rolling bearing described in JP-A-10-82426, the corrosion resistance is excellent, but the strength and fracture toughness are low. . When a load is applied to such a rolling bearing to some extent, cracks may propagate to the surface or the entire surface, and peeling or cracking may occur.

In particular, when the rolling bearing supports a radial load, the load is concentrated in the load zone of the outer ring, so that even under light load, peeling or cracking may occur and the life may be extremely shortened.
Japanese Patent Publication No. 7-30788 discloses a material of the inner ring for a rolling bearing provided with a rolling element between an inner ring fitted to a steel shaft body and an outer ring held by a housing. It is proposed that the outer ring material is made of a material having a smaller linear expansion coefficient, and that the inner ring material has a smaller linear expansion coefficient than that of the steel shaft material fitted to the inner ring. ing.

  In recent years, machine tools and various spindles tend to rotate at higher speeds. Rolling bearings that support rotating parts such as the above-mentioned machine tools can operate with high precision and under severe operating conditions. Required. Even in a normal bearing support device, the heat of the outer ring due to heat generation is relatively easy to dissipate through the housing, but the heat of the inner ring is difficult to dissipate from the shaft body side, so the temperature of the inner ring is lower than that of the outer ring. It tends to be higher.

  However, in the conventional rolling bearing in which the outer ring and the inner ring are made of the same material, for example, a high carbon chrome bearing steel such as bearing steel (SUJ2), the temperature of the inner ring is increased by the heat generated from the bearing or the heat from the outside. When the temperature difference becomes higher between the outer ring and the inner ring of the bearing, the internal clearance of the bearing becomes smaller than before the heat is not generated. For this reason, especially under high-speed rotation with severe service conditions, the radial clearance of the bearing may become insufficient, or the preload may become excessive due to a change in the clearance, resulting in seizure or an extremely short life.

  Normally, when the rotational speed is constant, a rolling bearing that has been corrected in advance so as to obtain an optimum clearance or an optimum preload under the specific use conditions may be selected and assembled. However, if the rotation conditions change variously, heat generation is large inside the bearing, or heat is conducted from the outside and a temperature difference occurs inside the bearing, the temperature of the bearing built into the rotating device should be detected. However, it is possible to adjust the internal clearance of the bearing or the preload generated by the change in the clearance by an external force (for example, a hydraulic mechanism), but there are drawbacks such as complicated and expensive equipment. It was.

In the technique described in the above Japanese Patent Publication No. 7-30788, the material of the inner ring is formed of a material having a smaller linear expansion coefficient than the material of the outer ring, and the linear expansion coefficient of the inner ring is fitted to the inner ring. Since it is smaller than the linear expansion coefficient of the material of the shaft body made of steel, the change in the clearance is smaller than when the inner ring and the outer ring are made of the same material.
However, if the rotation speed becomes higher and the heat generation increases and the temperature gradient inside the rolling device increases, the rolling element is made of bearing steel made of the same material as the outer ring, even if the thermal expansion amount of the inner ring is smaller than that of the outer ring. Because of the large amount of thermal expansion, there are cases where the clearance becomes too small and seizure occurs or the service life is extremely shortened.

  Japanese Unexamined Patent Publication No. 2000-205276 discloses a rolling bearing in which the thermal conductivity of the ceramic material constituting the outer ring is larger than the thermal conductivity of the ceramic material constituting the inner ring and the rolling element. The rolling bearing disclosed in the gazette has the following problems. In other words, some ceramic materials have insufficient thermal shock resistance and bending strength, so when used in a high temperature atmosphere or a high temperature / corrosion atmosphere, a temperature gradient is generated inside the bearing due to heating. A thermal stress is generated by the temperature gradient. In this case, a minute crack propagates to the surface of the outer ring or the inner ring, and a large amount of wear powder is generated, or the crack penetrates the member to cause a crack, which may shorten the life of the rolling bearing.

  On the other hand, since the rolling bearing used for a molten metal plating apparatus is used in the state immersed in the molten metal, it is requested | required that it is excellent in the corrosion resistance with respect to this molten metal. Such a rolling bearing is generally made of a steel material. However, the corrosion resistance of molten metal to the steel material is very strong, and the corrosion resistance of the steel material directly affects the rolling life of the rolling bearing. Therefore, rolling bearings have been proposed in which the portion in contact with the molten metal is made of a ceramic material (for example, Japanese Utility Model Publication Nos. 63-89428 and 61-90852).

However, Japanese Utility Model Publication Nos. 63-89428 and 61-90852 disclose the names of various ceramic materials constituting the rolling bearing (Si ₃ N ₄ , SiC, Al ₂ O ₃ , sialon). However, there is no description regarding the thermal shock value and bending strength. Even if the rolling bearing is composed of Si ₃ N ₄ , SiC, Al ₂ O ₃ , and sialon, if the thermal shock value and bending strength are insufficient, minute cracks propagate to the surface of the component member and wear powder May occur in large quantities, or cracks may penetrate through the constituent members to cause cracks.

The first object of the present invention is to effectively suppress a decrease in repeated positioning accuracy due to thermal expansion of the support or wear of the rolling element, particularly in a rolling device that operates at high speed, and can be used stably for a long period of time. An object of the present invention is to provide a rolling device capable of improving the strength of the support against bending moments and suppressing the wear of the rolling elements while maintaining high rigidity of the support.
A second object of the present invention is to provide a rolling device made of a ceramic material that has a long life even when used under high load in a high speed, corrosive environment, high temperature environment, or environment that supports a radial load. That is.

The third object of the present invention is to provide a rolling device that can be used at a location where thermal expansion is large due to a temperature rise or at a location where a temperature gradient is generated inside the rolling device.
A fourth object of the present invention is to provide a rolling device that is excellent in corrosion resistance, thermal shock resistance, and wear resistance and has a long life even when used at high speed in a high temperature / corrosion environment or a high temperature environment. It is.

A rolling device according to the present invention is disposed so as to be rotatable between a movable element capable of rotating or linearly moving, a support body supporting the movable element, and the movable element and the support body. A rolling device comprising a plurality of rolling elements, wherein at least one of the mover, the support, and the rolling elements is formed of any one of a ceramic material, a cermet, and a cemented carbide. And the ratio of the bending strength to the density of the material is 1.2 × 10 ⁷ mm or more, the ratio of the linear expansion coefficient between the rolling element and the mover at room temperature is 0.45 or less, and the rolling element and the support The linear expansion coefficient ratio of the body at normal temperature is 0.45 or less.

In a preferred embodiment of the present invention, the mover, the support, and the rolling element are formed of any one of ceramic material, cermet, and cemented carbide, and use a bending strength of 500 MPa or more. Sometimes have.
With such a configuration, cracks hardly propagate on the surface and inside of the ceramic material, and peeling and wear hardly occur. Therefore, even if the rolling device operates at a high speed, it has a long life.

In addition, if the bending strength in the use environment temperature of each material is 500 MPa or more and the specific strength is 1.2 × 10 ⁷ mm or more, the materials constituting the mover, the support, and the rolling element are all the same type. The material may be used, or all different types of materials may be used. Of course, two of the mover, the support, and the rolling element may be the same type, and the other one may be a different type of material.
In another preferred embodiment of the present invention, the mover and the rolling element are formed of any one of ceramic material, cermet, and cemented carbide, and have a bending strength of 500 MPa or more in use. Yes. The material constituting the mover and the rolling element has a specific strength of 1.2 × 10 ⁷ mm or more, and this specific strength is that of the material constituting the support (ceramic material, cermet or cemented carbide). It is set to a larger value.

With such a configuration, in a mover or rolling element on which hoop stress, centrifugal force, or the like acts during operation, cracks are less likely to propagate on the surface or inside, and peeling and wear are less likely to occur. As a result, peeling and wear due to hoop stress, which is the main cause of life when operating at high speed, can be effectively suppressed, so that the rolling device has a long life even when operating at high speed.
The specific strength of the material (ceramic material or cermet or cemented carbide) constituting the mover, support and rolling element is more preferably 1.5 × 10 ⁷ mm or more, and 1.8 × 10 ^7. Even more preferably, it is at least mm.

Here, if the specific strength is less than 1.2 × 10 ⁷ mm, cracks are likely to propagate from the surface or internal defects, and a large amount of wear powder may be generated or cracks may occur. The rolling device may have a short life. In particular, when the operating speed is high, the hoop stress acting on the mover due to centrifugal force causes cracks to propagate relatively easily even under light loads, causing separation and cracking, and the rolling device becomes extremely There is a risk of short life.

In another preferred embodiment of the present invention, the material (ceramic material, cermet, or cemented carbide) constituting the mover, the support, and the rolling element has a thermal shock of 1.5 times or more with respect to the use environment temperature. It has a bending strength of 500 MPa or more and a specific strength of 1.2 × 10 ⁷ mm or more (at the time of use environment temperature).
In such a configuration, even when a temperature gradient is generated inside the rolling device when used in a high temperature environment or a high temperature / corrosion environment and is heated, and even if thermal stress is generated by the temperature gradient, the mover In addition, microcracks are less likely to propagate to the surface of the support and wear and cracks are less likely to occur. Therefore, the rolling device has a long life even in a high temperature environment or a high temperature / corrosion environment.

The thermal shock value is more preferably 2.0 times or more with respect to the use environment temperature, and the bending strength is more preferably 500 MPa or more.
The thermal shock value is less than 1.5 times the operating environment temperature of the rolling device, the bending strength is less than 500 MPa when the rolling device is used, and the specific strength is less than 1.2 × 10 ⁷ mm. In some cases, it is used in a high temperature environment or in a high temperature / corrosive environment, and when heated, a temperature gradient is generated inside the rolling device, and when the thermal stress is generated by the temperature gradient, the surface of the mover or the support body In some cases, a minute crack propagates to generate a large amount of wear powder, or the crack penetrates the member to cause a crack, thereby shortening the life of the rolling device.

In another preferred embodiment of the present invention, the material (ceramic material or cermet or cemented carbide) constituting the mover, support and rolling element has a thermal shock value of 1.5 times the temperature of the molten metal. It is above and has a bending strength of 800 MPa or more and a specific strength of 1.2 × 10 ⁷ mm or more (at the time of molten metal contact).
If the thermal shock value of the material is 1.5 times or more of the temperature of the molten metal, the rolling device is heated when immersed in the molten metal or cooled when taken out from the molten metal. Therefore, even if thermal stress is generated, minute cracks are difficult to propagate to the surfaces of the mover and the support that are constituent members of the rolling device. Therefore, it is difficult to generate a large amount of wear powder and to cause cracks in the mover and the support.

Further, if the bending strength of the material is 800 MPa or more when the rolling device is used, a relatively high contact stress of 1 to 2.5 GPa is repeatedly applied between the mover and the rolling element, and the support and the rolling element. However, micro cracks are unlikely to occur on the surface, and a reduction in the service life can be suppressed.
Therefore, the rolling device has a long life even when used in a high-temperature environment in contact with the molten metal.

If the thermal shock value is less than 1.5 times the temperature of the molten metal, the bending strength during use is less than 800 Mpa, or the specific strength is less than 1.2 × 10 ⁷ mm, When a stress or repetitive stress is applied, minute cracks propagate to the surface of the mover or the support, and a large amount of wear powder is generated, or cracks are generated in the mover or the support. The life of the battery may be shortened.

Here, the thermal shock value means a numerical value obtained by the following method. That is, a test piece made of a high temperature (T ₁ ) ceramic material, cermet or cemented carbide is immersed in water at room temperature (T ₂ ) and rapidly cooled, and then the bending strength of the test piece is measured. At this time, the cooling temperature difference ΔT = T ₁ −T ₂ (° C.) at which the bending strength sharply decreases is defined as the thermal shock value.
Some conventional rolling devices are formed of a metal material (bearing steel or stainless steel) at least one of a movable element, a support body, and a rolling element. In this case, there is a possibility that the metal material will adhere to the contact point and seize, so that the life of the rolling device may be extremely short. In addition, the metal material may have insufficient rigidity and corrosion resistance.

However, as described above, when all of the mover, the support body and the rolling element are formed of a ceramic material, there are no such problems as described above, light weight and high rigidity, excellent wear resistance, and difficult to adhere. Furthermore, it is excellent in corrosion resistance and heat resistance.
Furthermore, when the rolling elements are made of a ceramic material with a high specific strength, the centrifugal force acting on the rolling elements during operation is reduced and higher speed compared to conventional rolling devices in which the rolling elements are made of a metal material. Can be operated, and the heat generation is also reduced.

The ceramic material that can be used in the present invention is not particularly limited. For example, silicon nitride (Si ₃ N ₄ ), zirconia (ZrO ₂ ), alumina (Al ₂ O ₃ ), silicon carbide (SiC) ), Aluminum nitride (AlN), boron carbide (B ₄ C), titanium boride (TiB ₂ ), boron nitride (BN), titanium carbide (TiC), titanium nitride (TiN), or Among these, a ceramic composite material in which two or more kinds of ceramic materials are combined can be exemplified.

In addition, the ceramic material used in the present invention can be blended with a fibrous filler in order to improve specific strength, fracture toughness, mechanical strength, and the like. The type of fibrous filler is not particularly limited, and examples thereof include silicon carbide whiskers, silicon nitride whiskers, alumina whiskers, and aluminum nitride whiskers.
The cermet and the cemented carbide that can be used in the present invention are not particularly limited. Cermet and cemented carbide are carbide powders of nine metals (W, Mo, Cr, Ta, Nb, V, Hf, Zr, Ti) belonging to groups IVa, Va, VIa in the periodic table. It is an alloy that is sintered and bonded using an iron group metal such as iron, cobalt, and nickel.

Examples of the cermet include TiC—Ni, TiC—Mo—Ni, TiC—Co, TiC—Mo ₂ C—Ni, TiC—Mo ₂ C—ZrC—Ni, TiC—Mo ₂ C—Co. _system, Mo 2 _{C-Ni-based, Ti (C, N) -Mo} 2 C-Ni _{system, TiC-TiN-Mo 2 C} -Ni _{system, TiC-TiN-Mo 2 C} -Co -based, TiC-TiN-Mo ₂ C—TaC—Ni, TiC—TiN—Mo ₂ C—WC—TaC—Ni, TiC—WC—Ni, Ti (C, N) —WC—Ni, TiC—Mo, Ti (C , N) -Mo system, boride based (MoB-Ni _{system, B 4 C / (W,} Mo) B 2 type, etc.) and the like.

_{Here, Ti (C, N) -Mo} 2 C-Ni -based, Ti (C, N) -WC -Ni -based, Ti (C, N) -Mo system, _TiC-Mo 2 _C-Ni system, TiC -Alloys obtained by sintering WC-Ni and TiC-Mo in nitrogen gas.
Typical composition of the _{cermet, TiC-30% Mo 2 C} -20% Ni, TiC-19% Mo 2 C-24% Ni, TiC-8% Mo 2 C-15% Ni, Ti (C, N) -25% Mo ₂ C-15% Ni, TiC-14% TiN-19% Mo ₂ C-24% Ni, TiC _0.7 N _0.3 -11% Mo ₂ C-24% Ni, TiC _{0.7 N 0.3 -19% Mo 2 C-} 24% Ni, TiC 0.7 N 0.3 -27% Mo 2 C-24% Ni, TiC-20% Mo-15% Ni, TiC-30% Mo- 15% Ni or the like.

Further, as the cemented carbide, for example, WC—Co, WC—Cr ₃ C ₂ —Co, WC—TaC—Co, WC—TiC—Co, WC—NbC—Co, WC—TaC— NbC-Co, WC-TiC-TaC-NbC-Co, WC-TiC-TaC-Co, WC-ZrC-Co, WC-TiC-ZrC-Co, WC-TaC-VC-Co, _{WC-TiC-Cr 3 C 2} -Co system, WC-TiC-TaC-based and the like.
Further, as a cemented carbide which is non-magnetic and has excellent corrosion resistance, WC—Ni, WC—Co—Ni, WC—Cr ₃ C ₂ —Mo ₂ C—Ni, WC—Ti (C, N) — Examples include TaC, WC—Ti (C, N), and Cr ₃ C ₂ —Ni.

  A typical composition of the WC—Co system is W: Co: C = 70.41 to 91.06: 3.0 to 25.0: 4.59 to 5.94. The typical composition of the WC-TaC-NbC-Co system is W: Co: Ta: Nb: C = 65.7 to 86.3: 5.8 to 25.0: 1.4 to 3.1. : 0.3 to 1.5: 4.7 to 5.8. Further, a typical composition of the WC-TiC-TaC-NbC-Co system is W: Co: Ta: Ti: Nb: C = 65.0-75.3: 6.0-10.7: 5.2. -7.2: 3.2-11.0: 1.6-2.4: 6.2-7.6. Furthermore, a typical composition of the WC—TaC—Co system is W: Co: Ta = 53.51 to 90.30: 3.5 to 25.0: 0.30 to 25.33. Furthermore, a typical composition of the WC—TiC—Co system is W: Co: Ti = 57.27 to 78.86: 4.0 to 13.0: 3.20 to 25.59. Furthermore, the typical composition of the WC—TiC—TaC—Co system is W: Co: Ta: Ti: C = 47.38 to 87.31: 3.0 to 10.0: 0.94 to 9.38. : 0.12 to 25.59: 5.96 to 10.15.

In a preferred embodiment of the present invention, at least one of the mover, the support and the rolling element is formed of a boride-based cermet and has a bending strength of 850 MPa or more when in use and 10 MPa · m ^1/2. It has the above fracture toughness. Others are made of ceramic material, cermet or cemented carbide.
The boride-based cermet is an alloy in which a hard phase of a boride having a high melting point is bonded by a bonded phase of a heat-resistant Ni-based alloy (the hard phase is M ₂ TB ₂ (M is mainly Mo and / or W). And T is mainly Ni)). With this structure, there is little decrease in hardness and bending strength from room temperature to high temperature range. Further, the boride-based cermet not only has excellent wear resistance, but also has an effect of reducing wear of the counterpart material. Furthermore, when the Ni-based alloy is present as a fine dispersed layer, the high-temperature strength of the binder phase can be improved without much deterioration of toughness.

In the present invention, it is preferable that the boride cermet has a bending strength of 850 MPa or more and a specific strength of 1.2 × 10 ⁷ mm or more at the use environment temperature. Considering the availability from the market, the bending strength at the use environment temperature is desirably 2600 MPa or less, but is not particularly limited. In particular, when a relatively high contact stress of 1 GPa or more is repeatedly applied between the mover and the rolling element, and between the support and the rolling element, minute cracks are unlikely to occur on the rolling element and the rolling contact surface, and the life and A decrease in acoustic characteristics can be suppressed.

The fracture toughness of the boride cermet is preferably 10 MPa · m ^1/2 or more. When the rolling device is heated by the use environment atmosphere or cooled to a room temperature atmosphere, a large temperature gradient is generated inside and a thermal stress is generated, but the fracture toughness is 10 MPa · m ^1/2 or more. For example, cracks due to thermal stress are unlikely to occur on the surface of the mover or the support. In order to obtain the above effects more sufficiently, it is more preferable that the fracture toughness of the boride cermet is 12 MPa · m ^1/2 or more.

Further, boride-based cermets have a thermal expansion coefficient of 8 to 9 × 10 ⁻⁶ / ° C., which is very close to metal. When the thermal expansion coefficient of the boride-based cermet is 8 to 9 × 10 ⁻⁶ / ° C., for example, when the roll used in the molten metal bath is immersed in the molten metal, or in the molten metal for maintenance or the like When the bearing is taken out of the bearing, even if the thermal stress generated due to the difference in the linear expansion coefficient between the shaft and the housing is applied to the bearing, the bearing material will not be cracked or chipped. Can be suppressed.

  Examples of the rolling device of the present invention include a rolling bearing, a linear motion guide device, a ball screw, and a linear motion bearing. When the rolling device is a rolling bearing, the rotating wheel corresponds to a mover, and the fixed wheel corresponds to a support. When the rolling device is a linear guide device, the slider corresponds to a mover or a support, and the guide rail corresponds to a support or a mover. When the rolling device is a ball screw, the nut corresponds to the mover and the screw shaft corresponds to the support. When the rolling device is a linear motion bearing, the outer cylinder corresponds to a mover and the shaft corresponds to a support.

In another embodiment of the present invention, the mover, the support, and the rolling element are made of a ceramic material, and the ceramic material has a fracture toughness value (MPa · m ^1/2 ) and a Vickers hardness (GPa). ) (A fracture toughness value / Vickers hardness) of 0.25 or more, and a specific strength of 1.2 × 10 ⁷ mm or more.
With such a configuration, cracks are unlikely to propagate on the surface or inside of the ceramic material, so that peeling and wear are unlikely to occur. Therefore, the rolling device can operate even under a heavy load and has a long life. That is, in use under a high load, it is more important that the fracture toughness value and the specific strength are superior from the viewpoint of preventing the propagation of cracks.

Each ceramic material forming the mover, the support, and the rolling element has a ratio of fracture toughness value to Vickers hardness (fracture toughness value / Vickers hardness) of 0.25 or more, and a specific strength of 1. As long as it is 2 × 10 ⁷ mm or more, the same kind of ceramic material may be used, or different kinds of ceramic materials may be used. Of course, two of the mover, the support, and the rolling element may be made of the same kind of ceramic material, and the other one may be made of a different kind of ceramic material.

In another preferred embodiment of the present invention, the ceramic material is silicon nitride containing silicon carbide particles having a specific strength of 1.2 × 10 ⁷ mm or more and a particle size of 1 μm or less.
Fine silicon carbide particles having a nanometer size with a particle size of 1 μm or less, blended in silicon nitride as a dispersed phase component, have a pinning effect on silicon nitride grains in the sintering process (stops crystal grain growth and refines the structure) Effect) and grain boundary movement are slowed down, silicon nitride grain growth is suppressed, and the microstructure of the sintered body is refined. Moreover, it distributes in the grain of silicon nitride and in grain boundaries, strengthens the grain boundaries, and acts as a bridge for cracks.

  As a result, separation and removal of particles from the sliding surface are suppressed and prevented, strength and toughness are improved, and wear resistance is also improved, so that the rolling device can operate stably for a long period of time. . In addition, the silicon carbide fine particles distributed in the grain boundaries of the silicon nitride matrix enhance the toughness of the silicon nitride matrix particles, and prevent and prevent the separation and dropping of the particles from the sliding surface. Since the wear coefficient of silicon carbide is smaller than that of silicon nitride (for example, silicon carbide: 0.2 to 0.4, silicon nitride: 0.5 to 0.6, the counterpart is a tungsten carbide sintered body) As a mixed effect, good sliding characteristics can be obtained even in an environment where lubrication is insufficient.

  Further, since silicon carbide is extremely hard (silicon carbide: Hv 2200 to 2400, silicon nitride: Hv 1200 to 1400) compared to silicon nitride, the dispersion of the fine particles contributes to the enhancement of the wear resistance of the sintered body. . Moreover, silicon carbide has a significantly higher thermal conductivity than silicon nitride (silicon carbide: 60 to 270 W / m · K (25 ° C.), silicon nitride: 17 to 31 W / m · K (25 ° C.)). The distribution of silicon carbide particles enhances the thermal conductivity of the sintered body, promotes thermal diffusion from the contact surface during actual use of the rolling device, and seizes due to the temperature rise of the contact surface Is suppressed.

In still another embodiment of the present invention, the ratio between the fracture toughness value of the ceramic material constituting the support and the Vickers hardness is A1, and the ratio between the fracture toughness value of the ceramic material constituting the rolling element and the Vickers hardness is When the ratio between the fracture toughness value of the ceramic material constituting the mover and the Vickers hardness is A3, A1 and A2 are A1, A2> A3, and the specific strength is 1.2 × 10 ⁷ mm. That's it.

  In the case of a rolling bearing that supports a radial load, the load concentrates in the load zone of the outer ring, so even under light loads, cracks easily propagate in the load zone of the outer ring, and the life of the rolling bearing becomes extremely long. It may be short. However, in the case of a rolling bearing having the above-described configuration, cracks are unlikely to propagate on the surface or inside of the ceramic material in the outer ring having a load zone where loads are concentrated, and peeling and wear are unlikely to occur. Therefore, it is possible to effectively suppress the peeling and wear in the outer ring, which is the main cause of the life of the rolling bearing that supports the radial load, and as a result, the rolling bearing has a long life even when a high radial load is applied. is there.

The ceramic material constituting the outer ring and the ceramic material constituting the rolling element may be the same or different.
The ratio of the fracture toughness value to the Vickers hardness of the ceramic material constituting the mover, the support and the rolling element needs to be 0.25 or more, more preferably 0.35 or more, and More preferably, it is 40 or more. By doing so, cracks are less likely to propagate on the surface or inside of the ceramic material, so that peeling and wear are less likely to occur. Therefore, the rolling device and the rolling bearing can be operated even under higher load conditions, and have a longer life.

If the ratio between the fracture toughness value of the ceramic material and the Vickers hardness is less than 0.25 and the specific strength is less than 1.2 × 10 ⁷ mm, cracks are likely to propagate from the surface and internal defects. In some cases, a large amount of wear powder is generated or cracks occur, and the life of a rolling device such as a rolling bearing is shortened.
The ceramic material that can be used in the present invention is not particularly limited, and silicon nitride (Si ₃ N ₄ ), zirconia (ZrO ₂ ), alumina (Al ₂ O ₃ ), and silicon carbide (SiC) Aluminum nitride (AlN), boron carbide (B ₄ C), titanium boride (TiB ₂ ), boron nitride (BN), titanium carbide (TiC), titanium nitride (TiN), or these Examples thereof include ceramic composite materials in which two or more of them are combined.

The ceramic material used in the present invention can be blended with a fibrous filler in order to improve fracture toughness, mechanical strength, and the like. The type of fibrous filler is not particularly limited, and examples thereof include silicon carbide whiskers, silicon nitride whiskers, alumina whiskers, and aluminum nitride whiskers.
As the fracture toughness value of the ceramic material, the fracture toughness value calculated based on the IF method of JIS R1607 for the flat surface of the ceramic material is used. In addition, as the Vickers hardness, a value measured based on JIS R1610 for a flat surface of a ceramic material is used.

  Furthermore, examples of the rolling device of the present invention include a linear guide device, a ball screw, a linear motion bearing and the like in addition to a rolling bearing. When the rolling device is a rolling bearing, the rotating wheel (usually the outer ring) corresponds to the mover, and the fixed wheel (usually the inner ring) corresponds to the support. When the rolling device is a linear guide device, the slider or guide rail corresponds to a mover, and the guide rail or slider corresponds to a support. When the rolling device is a ball screw, the nut corresponds to the mover and the screw shaft corresponds to the support. When the rolling device is a linear motion bearing, the outer cylinder corresponds to a mover and the shaft corresponds to a support.

In another embodiment of the present invention, the ratio of the linear expansion coefficient of the rolling element and the mover at normal temperature is 0.45 or less, and the ratio of the linear expansion coefficient of the rolling element to the support is normal temperature. 0.45 or less. Here, the normal temperature may be 20 ° C., for example.
In another preferred embodiment of the present invention, the rolling element has a ratio of the fracture toughness value (MPa · m ^1/2 ) to the Vickers hardness (GPa) of 0.40 or more, preferably 0.425 or more. And a specific strength of 1.2 × 10 ⁷ mm or more.

Preferably, the rolling element preferably has a ratio of fracture toughness value (MPa · m ^1/2 ) to Vickers hardness (GPa) of 0.40 or more and a specific strength of 1.2 × 10 ⁷ mm or more. It is formed of a hard alloy (an alloy obtained by sintering and bonding tungsten (W) carbide powder using an iron group metal such as iron, cobalt, or nickel).
When the ratio of the linear expansion coefficients of the rolling element and the movable element and the rolling element and the support at normal temperature are both 0.45 or less, the thermal expansion amount of the rolling element is high even under conditions of high speed rotation and high heat generation. Relatively smaller than the thermal expansion amount of the inner ring and the outer ring. For this reason, it is possible to effectively reduce the increase in preload due to the temperature gradient, making it difficult for seizure to occur even under conditions where heat generation increases under high speed rotation, and it is possible to rotate under high speed conditions and under high speed rotation. It can operate for a long time (see FIG. 27).

Furthermore, when the ratio of the linear expansion coefficient of the rolling element to the linear expansion coefficient of the support is 0.40 or less, the amount of thermal expansion of the rolling element can be further effectively suppressed.
However, the lower limit of the linear expansion coefficient ratio is considered to be 0.2 in consideration of the strength required for rolling devices such as bearings in a range that can be implemented industrially, but is small in terms of preventing clearance reduction. Therefore, it is not limited to 0.2 or more.

  On the other hand, when the ratio of the linear expansion coefficient of the rolling element to the linear expansion coefficient of the mover at room temperature and the ratio of the linear expansion coefficient of the rolling element to the linear expansion coefficient of the support exceed 0.45 When the increase in preload due to the temperature gradient cannot be sufficiently mitigated and heat generation increases under high-speed rotation conditions, the clearance may become too small, resulting in seizure and extremely short life.

The rolling element is a ceramic material or cemented carbide with a ratio of fracture toughness value (MPa · m ^1/2 ) to Vickers hardness (GPa) of 0.40 or more and a specific strength of 1.2 × 10 ⁷ mm or more. It is preferable that When the rolling element is a ceramic material or cemented carbide having a fracture toughness ratio to Vickers hardness of 0.40 or more and a specific strength of 1.2 × 10 ⁷ mm or more, the rolling element is subjected to high-speed rotation conditions. Even if a large centrifugal force is applied to the rolling elements, cracks do not easily occur or propagate on the surface or inside of the rolling elements made of ceramic material or cemented carbide. In addition to being able to operate under higher speed rotation conditions, it is also possible to operate for a longer life under higher speed rotation conditions (see FIG. 28).

In another embodiment of the present invention, the mover or the support is a guide rail of a linear guide device, and the guide rail is made of any one material of ceramic material, cermet, and cemented carbide. The flat portion is formed and finished with a surface roughness of 0.5 μmRa or less.
As described above, the guide rail is formed of a ceramic material, cermet or cemented carbide, for example, an electronic component suction head of a mounting device is attached to one end of the guide rail, and the head takes 0.2 cycle or less for one cycle. Even when moving up and down at a high speed or when revolving by being attached to a drum, a guide rail having sufficient strength against the inertial force generated by acceleration, head weight or the like can be obtained. Also, by finishing each flat part of the guide rail with a surface roughness of 0.5 μmRa or less, stress concentration due to minute irregularities on the surface of the guide rail is reduced, so that the inertial force generated by the rail's own weight or head weight is reduced. A guide rail having sufficient strength can be obtained.

In this case, it is preferable that the ceramic material constituting the guide rail has a specific strength of 2 × 10 ⁷ mm or more. In the case of cermet or cemented carbide, one having a specific strength of 1.7 × 10 ⁷ mm or more is preferable. Cermet and cemented carbide have a fracture toughness value larger than that of the ceramic material and are not easily damaged. Further, the specific strength of the cermet or the cemented carbide is more preferably 1.95 × 10 ⁷ mm or more, and 2.8 × 10 ⁷ mm or less is desirable from the viewpoint of market procurement, but it is not particularly limited. As described above, a guide rail having a sufficient strength can be obtained.

  Also, by finishing each flat part of the guide rail with a surface roughness of 0.5 μmRa or less, stress concentration due to minute irregularities on the surface of the guide rail is reduced, so inertial force generated by the rail's own weight or head weight is reduced. A guide rail having sufficient strength can be obtained. In this case, it is desirable that finish grinding on the flat portion of the guide rail is performed so that the ground line remains in the longitudinal direction of the guide rail, that is, in a direction perpendicular to the bending moment due to inertial force. When notches are formed to avoid interference with mounting parts, and the grinding line is unavoidably in the width direction of the guide rail, the flat surface of the guide rail should be finished with a surface roughness of 0.3 μmRa or less. Is preferred. Note that if the flat portion of the guide rail is finished with a surface roughness of, for example, 0.05 μmRa or less, the influence of the surface roughness of the flat portion on the strength of the guide rail is almost negligible. For this reason, a surface roughness of 0.05 μmRa or less simply increases the cost. Therefore, the finish roughness range of the guide rail flat portion is 0.5 μmRa to 0.05 μmRa, preferably 0.3 μmRa to 0. .05 μm Ra is desirable.

The ceramic material constituting the guide rail preferably has a fracture toughness value of 5 MPa · m ^0.5 or more and a thermal conductivity of 46 W / m · K or more.
The ceramic material constituting the guide rail is preferably a ceramic material mainly composed of silicon nitride, and the ratio of the crystalline phase in the grain boundary phase contained in the sintered body is 10% by volume or more. is there.

  By using a high thermal conductivity ceramic material as the rail material, the heat generated on the sliding surface can be released to the outside, and the temperature rise of the rail material can be effectively suppressed. At the same time, temperature rise can be suppressed at the contact surface between the rail groove surface and the rolling element. Therefore, it is possible to solve the short-term and long-term positioning accuracy degradation problems such as the thermal expansion of the entire rail and the wear of the rolling elements that cause a decrease in the amount of internal preload. In particular, when the thermal conductivity of the rail material is 46 W / m · K or more, and more preferably 72 W / m · K or more, the portion other than the rail (rolling element, slider, etc.) is replaced with bearing steel (thermal conductivity: 46 W / Even in the case of m · K), the rail itself does not become a heat insulation source and does not disturb the heat conduction. However, even if the thermal conductivity of only the rail is particularly good, the effect is low if the thermal conductivity of other parts such as rolling elements and sliders is not very good, so the upper limit of the thermal conductivity of the rail material is Although it is preferably up to 100 W / m · K, it is not particularly limited.

Here, when such a high thermal conductive ceramic is used as a rail material, the fracture toughness value of the rail material is ^preferably 5 MPa · m ^0.5 or more. When the fracture toughness value of the rail material is 5 MPa · m ^0.5 or more, the rail material can be used without being damaged by repeated loads acting on the guide rail during operation of the linear motion guide device. In particular, when the use environment is severe, the fracture toughness value of the rail material is preferably 6 MPa · m ^0.5 or more. Further, the upper limit value of the fracture toughness value is desirably up to 8 MPa · m ^0.5 depending on the balance with market procurement and bending strength, but is not particularly limited. At the same time, if silicon nitride having a specific strength of 2.0 × 10 ⁷ mm or more is used as a rail material, it can be suitably used in the above applications.

In order to improve the thermal conductivity of these silicon nitride sintered bodies, it is necessary to optimize factors that hinder the propagation of lattice vibration in the sintered body, that is, grain boundaries, defects, crystal structures, and the like.
For example, Japanese Patent Laid-Open No. 9-165265 proposes a method in which silicon nitride crystal grains are arranged in one direction to improve the thermal conductivity in a specific direction. Similarly, Japanese Patent Application Laid-Open No. 9-157030 proposes a material in which the minor axis diameter is set to 2 μm or more to reduce the grain boundary and the crystal grains have orientation.
Here, since the extreme enlargement of the crystal grain size causes the strength deterioration of the rail material, it is necessary to set the strength within the range required for the bearing member.

Moreover, in order to obtain a more preferable ceramic material mainly composed of high thermal conductivity silicon nitride, it is desirable to reduce internal defects or optimize the crystal structure.
Particularly harmful as internal defects are vacancies remaining in the sintered body during sintering, and if these are present in a large amount in the sintered body, the thermal conductivity of the sintered body is significantly lowered. Therefore, in the silicon nitride used for the above applications, the effect of increasing the thermal conductivity can be obtained by reducing the porosity. In particular, when the porosity inside the sintered body is 2% or less, it can be suitably used without generating vibration of the bearing, and the thermal conductivity can be effectively increased. At this time, in order to reduce the porosity, it is desirable to sinter the ceramic material by pressure sintering such as HIP sintering or gas pressure sintering.

Factors that reduce the thermal conductivity of silicon nitride, the influence of the sintering aid phase present at the grain boundaries is considered as the sintering aid, in general, Al 2 O _{3, MgO,} a metal such as CeO It is often selected from oxides and rare earth oxides such as Y ₂ O ₃ , Yb ₂ O ₃ , La ₂ O _3, and 20% by volume of the entire sintered body is added as the upper limit. In particular, there are many Al ₂ O ₃ —Y ₂ O ₃ -based ones and Al ₂ O ₃ —MgO ones, which are present in the grain boundary of the sintered body in an amorphous state. Here, in general, solids having an amorphous structure are difficult to propagate lattice vibration and have low thermal conductivity. Accordingly, silicon nitride having a large amount of these in the grain boundary has a low thermal conductivity. Conversely, by increasing the crystallinity of the sintering aid portion, the thermal conductivity in the sintering aid portion can be improved and high thermal conductivity silicon nitride can be obtained. In order to increase the crystallinity of the sintering aid, the cooling rate after sintering may be adjusted. In other words, if the cooling rate is high, the atomic arrangement of the sintering aid component is not in time, and the room temperature phase is formed by taking over the amorphous material in the high temperature state as it is. It becomes a room temperature phase. At this time, in order to further improve the thermal conductivity, an oxide selected from lanthanoid yarns such as La, Ce, Pr, Nd, and Ho may be added as an auxiliary component.

  In addition, when a notch for attaching a head or the like is formed on the guide rail, the corner of the notch is set to have a radius of curvature of 0.1 mm or more to concentrate on the corner of the notch. To reduce the stress. In addition, regarding the change in the cross-sectional area of the notch and the rail necessary for mounting to the head and the testing machine, the inertia is obtained by setting the shape factor to 5 or less, for example, without creating an acute angle as much as possible. Stress concentration on the corners due to force can be reduced. Here, as a method of reducing the shape factor, a method of forming the corner of the notch in an arc shape is common, but in order to reduce the shape factor to 5 or less, the corner of the notch is reduced. It is desirable to form with a radius of curvature of 0.1 mm or more, preferably 0.3 mm or more. If the radius of curvature of the corner is too large, it interferes with the parts attached to the guide rail. Therefore, it is desirable that the radius of curvature of the corner is 1 mm or less at the maximum, and the shape factor at this time is about 1-2. Become. As other methods for reducing stress concentration, there are a method of forming a chamfer at the bottom of the notch and a method of increasing the notch angle. Absent.

In addition to silicon nitride, zirconia, alumina, silicon carbide, titanium boride, etc., these composite sintered bodies can be used as the ceramic material constituting the guide rail. Among these, silicon nitride has high rigidity and high strength. This is particularly preferable because it has a fracture toughness value. In this case, if the fracture toughness value is 5 MPa · m ^0.5 or more and the hardness is 12 GPa or more, the silicon nitride material can be used more suitably in terms of fracture strength.

Silicon nitride is obtained by pressure sintering such as HIP method, gas pressure sintering method, etc., and columnar crystals grown in a columnar shape having an average width of 3 μm or less and a length of 4 μm or more are 70% or more of the entire silicon nitride grains, preferably 90 However, any material that satisfies the condition of specific strength may be sintered at normal pressure. Further, the auxiliary component is selected from metal oxides such as Al ₂ O ₃ , MgO and CeO or rare earth oxides such as Y ₂ O ₃ , Yb ₂ O ₃ and La ₂ O _3, and the entire sintered body The one added up to the upper limit of 20 wt% can be used. Further, if defects such as vacancies and foreign matters inside the material have an equivalent circle diameter of 50 μm or less, preferably 20 μm or less, local material strength deterioration can be suppressed and the reliability of the material can be improved.

In a preferred embodiment of the present invention, the rolling element has a hard film covering the surface of the rolling element, and the hard film has a thickness of 0.1 μm to 5.0 μm.
When a hard coating having a film thickness of 0.1 μm to 5.0 μm is formed on the surface of the rolling element and the surface of the rolling element is coated with the hard coating, the wear resistance of the rolling element is improved, and the linear motion guide device Since the initial setting preload is maintained over a long period of time, the required positioning accuracy can be ensured over a long period of time without reducing the rigidity of the guide rail.

  Here, the reason why the film thickness of the hard coating is 0.1 μm to 5.0 μm is that, when the film thickness of the hard coating is less than 0.1 μm, the longitudinal elastic modulus (Young's modulus) of the base metal constituting the rolling element ) And that of the hard coating, which causes the hard coating to peel off or drop off easily, and the hard coating strips cause abnormal wear such as chipping on the rolling element rolling grooves and rolling element surface. This is because there is a possibility of occurrence. Moreover, when the film thickness of a hard film exceeds 5.0 micrometers, the internal stress of a hard film becomes large. This is because the hard coating is easily peeled off from the surface of the rolling element, and abnormal wear such as chipping may occur on the rolling element rolling groove and the surface of the rolling element due to the peeling piece of the hard coating. Therefore, the film thickness of the hard coating formed on the surface of the rolling element is desirably in the range of 0.1 μm to 5.0 μm, preferably 0.5 μm to 5.0 μm.

The hard coating is at least one of TiN, TiC, TiAlN, TiCN, Cr ₇ C ₃ , Cr ₂ O ₃ , CrN, WC, B ₄ C, cBN, CN, TaC, TaN, ZrN, diamond-like carbon, and diamond. In this way, the hard film is made of TiN, TiC, TiAlN, TiCN, Cr ₇ C ₃ , Cr ₂ O ₃ , CrN, WC, B ₄ C, cBN, CN, TaC, TaN, ZrN, diamond-like carbon In addition, since the wear resistance of the hard coating is improved by using at least one material of diamond and diamond, the wear of the rolling elements can be effectively suppressed.

Here, as a method of forming a hard film on the surface of the rolling element, for example, various CVD such as plasma CVD, thermal CVD, photo CVD, ion plating method (holo cathode method and arc method), sputtering, ion beam forming method, Various methods such as ionized vapor deposition can be used. When a hard film is formed on the surface of the rolling element using the ion plating method, for example, after evacuating the chamber to 10 ⁻⁴ Pa or less, After the rolling element surface is cleaned by bombardment, the temperature of the rolling element surface is set to 400 ° C. to 500 ° C., and the target (for example, Ti material in the case of Ti-based coating, Cr material in the case of Cr-based coating, diamond-like carbon) -200V to -300V vias for graphite or diamond coatings) Applying a voltage, the discharge current as 80A～150A, a process gas (e.g., nitrogen gas in the case of nitrides, in the case of carbides methane such as CH ₄₎ as necessary to introduce into the chamber a hard coating A film can be formed.

  When a diamond-like carbon film or a diamond film is formed on the surface of the rolling element using plasma CVD, the surface of the rolling element is bombarded (dry cleaning) with argon gas, and then tetramethylsilane gas is ionized with ion gas. A diamond-like carbon coating is formed on the surface of the rolling element by forming plasma into an intermediate layer on the surface of the rolling element, and subsequently introducing benzene into the chamber, and then plasminizing the benzene introduced into the chamber with ion gas. Alternatively, a diamond coating can be formed. In this case, other metals such as tungsten, titanium, chromium and silicon may be added to the diamond-like carbon film or the diamond film.

In a preferred embodiment of the present invention, the rolling element has a surface hardness of 0.6 to 1.5 times the hardness of the guide rail.
By setting the surface hardness of the rolling element within the range of 0.6 to 1.5 times the hardness of the guide rail, wear of the rolling element is suppressed and damage to the surface of the guide rail is suppressed. Since the initial setting preload of the rolling element is maintained for a long time, the required positioning accuracy can be ensured for a long time without causing a decrease in the rigidity of the guide rail.

  The reason why the surface hardness of the rolling element is in the range of 0.6 times to 1.5 times the hardness of the guide rail is as follows. That is, when the ratio of the surface hardness of the rolling element to the hardness of the guide rail is less than 0.6, the surface hardness of the rolling element is lower than the surface hardness of the guide rail. As a result, the wear of the rolling element surface is promoted and the preload is released in a short period of time, so that the required positioning accuracy may not be maintained over a long period of time. On the contrary, when the ratio of the surface hardness of the rolling element to the hardness of the guide rail exceeds 1.5, the surface hardness of the rolling element becomes too hard compared with the surface hardness of the guide rail. Wear and chipping may increase significantly.

  The material of the rolling element is not particularly limited as long as the surface hardness of the rolling element is in the range of 0.6 to 1.5 times the hardness of the guide rail. For example, silicon nitride, zirconia, alumina, Ceramic materials mainly composed of silicon carbide, aluminum nitride, boron carbide, titanium boride, boron nitride, titanium carbide, titanium nitride, ceramic composite materials obtained by combining these materials, or groups IVa and Va in the periodic table Nine kinds of metals belonging to any one of group VIa and group VIa (for example, W, Mo, Cr, Ta, Nb, V, Hf, Zr, Ti) are used as iron group metals such as iron, cobalt, and nickel. Cemented carbide and cermet, which are sintered and bonded, and hard titanium-based alloys (Ti-W-TiC-based alloys) can be preferably used.

The ceramic material used in the present invention may contain a fibrous filler in order to improve the fracture toughness value and mechanical strength. Although it does not specifically limit as a fibrous filler, For example, a silicon carbide type whisker, a silicon nitride type whisker, an alumina type whisker, an aluminum nitride type whisker, etc. can be used.
As the cemented carbide, for example, WC-Co alloy, WC-Cr ₃ C ₂ -Co alloy, WC-TaC-Co alloy, WC-TiC-Co alloy, WC-NbC-Co alloy, WC- TaC-NbC-Co alloy, WC-TiC-TaC-NbC-Co alloy, WC-TiC-TaC-Co alloy, WC-ZrC-Co alloy, WC-TiC-ZrC-Co alloy, WC- TaC-VC-Co alloy, WC-Cr ₃ C ₂ -Co alloy, WC-TiC-Cr ₃ C ₂ -Co alloy, etc. can be used, and it is non-magnetic and has improved corrosion resistance. Examples of alloys include WC—Ni alloys, WC—Co—Ni alloys, WC—Cr ₃ C ₂ —Mo ₂ C—Ni alloys, WC—Ti (C, N) —TaC alloys, WC—Ti ( C, N) -based alloy, Cr ₃ C ₂ − Ni-based alloys and the like can also be used.

  Here, a typical composition of the WC-Co alloy is W: Co: C = 70.41 to 91.06 wt%: 3.0 to 25.0 wt%: 4.59 to 5.94 wt%. As a typical composition of the WC—TaC—NbC—Co alloy, W: Co: Ta: Nb: C = 65.7 to 86.3 wt%: 5.8 to 25.0 wt%: 1.4 to 3.1 wt%: 0.3 to 1.5 wt%: 4.7 to 5.8 wt%. Moreover, as a typical composition of a WC-TiC-TaC-NbC-Co type alloy, W: Co: Ta: Ti: Nb: C = 65.0-75.3 wt%: 6.0-10.7 wt% : 5.2 to 7.2 wt%: 3.2 to 11.0 wt%: 1.6 to 2.4 wt%: 6.2 to 7.6 wt%, which is a typical WC-TaC-Co alloy The composition is W: Co: Ta = 53.51 to 90.30 wt%: 3.5 to 25.0 wt%: 0.30 to 25.33 wt%. Further, a typical composition of the WC—TiC—Co alloy is W: Co: Ti = 57.27 to 78.86 wt: 4.0 to 13.0 wt%: 3.20 to 25.59 wt%. As a typical composition of the WC—TiC—TaC—Co alloy, W: Co: Ta: Ti: C = 47.38 to 87.31 wt%, 3.0 to 10.0 wt%, 0.94 to 9.38 wt%, 0.12 to 25.59 wt%, 5.96 to 10.15 wt%.

The cermet, TiC-Ni based alloy, TiC-Mo-Ni based alloy, TiC-Co alloy, _TiC-Mo 2 _C-Ni based _{alloy, TiC-Mo 2 C-ZrC} -Ni based alloy, TiC-Mo ₂ C—Co alloy, Mo ₂ C—Ni alloy, Ti (C, N) —Mo ₂ C—Ni alloy, TiC—TiN—Mo ₂ C—Ni alloy, TiC—TiN—Mo ₂ C—Co system _{alloy, TiC-TiN-Mo 2 C} -TaC-Ni -based _{alloy, TiC-TiN-Mo 2 C} -WC-TaC-Ni -based alloy, TiC-WC-Ni alloy, Ti (C, N) -WC- Ni-based alloy, TiC-Mo-based alloy, Ti (C, N) -Mo system, boride based (MoB-Ni _{system, B 4 C / (W,} Mo) B 2 system) or the like can be used alloys. _{Here, Ti (C, N) -Mo} 2 C-Ni alloy, Ti (C, N) -WC -Ni -based alloy and Ti (C, N) -Mo based alloy, _TiC-Mo 2 _C-Ni It is a metal obtained by sintering a titanium alloy, a TiC-WC-Ni alloy, or a TiC-Mo alloy in nitrogen gas (N ₂ ).

The typical composition of cermet is TiC-30% Mo ₂ C-20% Ni, TiC-19% Mo ₂ C-24% Ni, TiC-8% Mo ₂ C-15% Ni, Ti (C, N _{) -25% Mo 2 C-15} % Ni, TiC-14% TiN-19% Mo 2 C-24% Ni, TiC 0.7 N 0.3 -11% Mo 2 C-24% Ni, TiC 0. _{7 N 0.3 -19% Mo 2 C} -24% Ni, TiC 0.7 N 0.3 -27% Mo 2 C-24% Ni, TiC-20% Mo-15% Ni, TiC-30% Mo -15% Ni.

In a preferred embodiment of the present invention, the rolling element is covered with a nitride film, and the nitride film has a hardness of Hv800 to Hv1400. When the rolling element is covered with a nitride film having a hardness of Hv800 to Hv1400, the difference in hardness between the rail material and the surface of the rolling element is reduced, so that the promotion of wear can be suppressed. When materials having different hardnesses wear (rub against each other), the lower the hardness, the easier the plastic deformation, and the easier the wear. Therefore, it is preferable to make the difference in hardness as small as possible. Here, when the hardness of the nitride film is less than Hv800, the difference in hardness from the rail material becomes large, and thus wear of the rolling elements may be promoted. When the hardness of the nitride film exceeds Hv 1400, Fe ₂ N is generated on the surface of the nitride film, and the surface of the rolling element becomes brittle. Thereby, peeling of the nitride film or the like may occur during use, and the life may be reduced. Therefore, the hardness of the nitride film is preferably in the range of Hv800 to Hv1400.

  In another preferred embodiment of the present invention, the rolling element is coated with a composite carbide layer containing Cr carbide and carbon, and the composite carbide layer has a hardness of Hv1000 to Hv1800. When a rolling element is coated with a composite carbide layer having a hardness of Hv1000 to Hv1800, the difference in hardness between the hardness of the guide rail material and the hardness of the rolling element surface is reduced, so that the rolling element surface and the rolling element rolling groove surface It can suppress that wear is accelerated. When materials having different hardness are worn, the lower the hardness, the easier the plastic deformation occurs. As a result, the material is easily worn preferentially. Therefore, it is preferable to make the difference in hardness as small as possible.

  Here, when the hardness of the composite carbide layer is less than Hv1000, the hardness difference from the race material becomes large, and thus wear of the rolling elements may be promoted. Further, when the hardness of the composite carbide layer exceeds Hv1800, the composite carbide layer formed on the surface of the rolling element becomes very brittle, and peeling may occur during use, which may shorten the life. Therefore, the hardness of the composite carbide layer is preferably in the range of Hv1000 to Hv1800.

  In another preferred embodiment of the present invention, the rolling element is coated with a boride film, and the boride film has a hardness of Hv1000 to Hv1700. When the rolling elements are coated with a boride film having a hardness of Hv1000 to Hv1700, the difference in hardness between the guide rail material and the rolling element surface is reduced, so that the wear of the rolling elements and the guide rail is promoted. Can be suppressed. When materials having different hardnesses are slid, the lower the hardness, the easier the plastic deformation occurs. As a result, the materials tend to be preferentially worn. Therefore, it is preferable to make the difference in hardness as small as possible.

  Here, when the hardness of the boride film is less than Hv1000, the difference in hardness from the rail material becomes large, so that wear of the rolling elements may be promoted. When the hardness of the boride film exceeds Hv 1700, FeB of Hv 1700 or more is formed on the surface of the boride film. As a result, the surface layer of the rolling element becomes very brittle, and peeling or the like occurs during use, which may shorten the life. Accordingly, the hardness of the boride film is preferably in the range of Hv1000 to Hv1700.

  The hard coating, nitride film, composite carbide layer, and boride film preferably have a surface roughness of 0.05 μmRa or less. Here, when the surface roughness exceeds 0.05 μmRa, the minute irregularities on the surface of the rolling element are likely to be in direct contact with the surface of the rolling element rolling groove, and the rolling element rolling is performed by a film covering the surface of the rolling element. The surface of the groove may be damaged or wear may be accelerated. Therefore, the surface roughness of the film covering the surface of the rolling element is preferably 0.05 μmRa or less, and preferably 0.02 μmRa or less.

In a preferred embodiment of the present invention, the guide rail has a rolling element rolling groove, and the rolling element rolling groove has a surface roughness of 0.2 μmRa or less along the width direction, and extends along the longitudinal direction. The surface roughness is 0.1 μmRa or less.
As described above, when a ceramic material, cermet or cemented carbide is used for the rail material for the purpose of improving the accuracy and speed of the linear motion guide device, (1) the surface pressure at the contact surface with the rolling element increases. (2) Because the surface hardness of the rolling element rolling groove in contact with the rolling element is about twice or more that of the rolling element, wear of the rolling element is promoted, and linear motion guidance is achieved in a short time. The preload of the device may be reduced. Here, as a result of investigating such rolling element wear reduction, the amount of wear of the rolling element greatly varies depending on the surface roughness of the rolling element rolling groove of the guide rail, and further due to the unevenness of the convex and concave portions of the roughness. The knowledge that the wear tendency is extremely different was obtained.

  That is, by setting the surface roughness in the width direction of the rolling element rolling groove to 0.2 μmRa or less and the surface roughness in the longitudinal direction of the rolling element rolling groove to 0.1 μmRa or less, the rolling element rolling groove It can suppress effectively that the surface of a rolling element is damaged by the minute surface unevenness | corrugation which exists in the surface. Here, only focusing on the surface roughness of the rolling element rolling groove in the rolling direction (longitudinal direction) of the rolling element, the surface roughness of the rolling element generated by minute vibrations in the width direction of the guide rail. It is difficult to suppress damage. That is, only when both the surface roughness in the width direction and the surface roughness in the longitudinal direction of the rolling element rolling groove satisfy the above conditions, wear damage on the rolling element surface can be effectively suppressed. In this case, there is no particular lower limit for the surface roughness in the width direction and the surface roughness in the longitudinal direction. However, if the surface roughness is smaller than the surface roughness of the rolling element, the effect of suppressing the rolling element wear will be reduced. This also increases the cost of the material, which is not desirable.

Further, in the linear motion guide device used at a high speed as described above, it is difficult to form an oil film on the surface of the rolling element rolling groove. In particular, if there is a convex part having an extremely high height on the surface of the rolling element rolling groove, oil film breakage is likely to occur there. Since such oil film breakage is a factor that promotes wear of the rolling elements, the surface irregularities on the rolling element rolling groove surface should be minimized as much as possible for the linear motion guide devices used at high speeds as described above. Is desirable.
Here, the ratio of the surface convex portion and the surface concave portion to the average line of roughness is defined by the definition of so-called roughness distortion (Sk),

で表される。ここで、Ｒｑは二乗平均粗さ（ＲＭＳ）、ｎは正の整数、Ｙ（ｉ）は粗さの各山（ｉ番目）の高さを平均線よりも上をプラス、下をマイナスとしてそれぞれ示している。すなわち、粗さの凸部（平均線よりも上の部分）の高さの総和が凹部の高さの総和よりも小さいとゆがみ度Ｓｋは負となり、逆の場合にはＳｋは正となる。

It is represented by Here, Rq is the root mean square roughness (RMS), n is a positive integer, Y (i) is the height of each roughness peak (i-th) plus above the average line, and minus below Show. That is, when the total sum of the heights of the convex portions of roughness (portions above the average line) is smaller than the total sum of the heights of the concave portions, the skew degree Sk is negative, and in the opposite case, Sk is positive.

  Therefore, in order to effectively form an oil film on the surface of the rolling element rolling groove, the number of extreme surface protrusions that cause the lubricating oil to break is reduced, and the lubricating oil is evenly distributed on the surface of the rolling groove. It is good to go around. In other words, it is preferable that the rolling groove is formed so that Sk is negative so that the lubricating oil is evenly distributed on the surface of the rolling groove. However, even if the Sk value is -3 or less, no further effect can be expected, and this also causes a cost increase. Therefore, the Sk value is preferably in the range of -3 to 0.

As described above, according to the present invention, in a rolling device that operates at high speed, it is possible to effectively suppress a decrease in positioning accuracy due to thermal expansion of the support or rolling element wear, and to be used stably for a long period of time. Thus, it is possible to obtain a rolling device capable of improving the strength of the guide rail against the bending moment and suppressing the wear of the rolling element while maintaining high rigidity of the guide rail.
Further, there is no increase in vibration for a long period of time, and the reliability can be enhanced with high accuracy and strength. Furthermore, it is possible to reduce the stress concentration at the corners of the notches provided on the guide rail. Further, it is possible to improve the strength of the guide rail with respect to the bending moment while maintaining the high rigidity of the guide rail and to suppress wear of the guide rail and the rolling elements.

In addition, a rolling device made of a ceramic material having a long life can be obtained even when used under a high load in a high-speed, corrosive environment, high-temperature environment, or environment that supports a radial load.
Moreover, the rolling device which can be used in the location where a thermal expansion is large by the temperature rise, or the location where a temperature gradient arises inside a rolling device can be obtained.
In addition, a rolling device having excellent corrosion resistance, thermal shock resistance, and wear resistance and having a long life even when used at high speed in a high temperature / corrosion environment or a high temperature environment can be obtained.

[Embodiment 1]
FIG. 1 is a view showing a linear motion guide device which is an embodiment of a rolling device according to the present invention. In the figure, reference numeral 10 denotes an electronic component suction head, 11 denotes a head lifting mechanism for reciprocating the electronic component suction head 10 in the vertical direction, and this head lifting mechanism 11 includes a drive device (not shown) and its drive. It comprises a plurality of linear motion guide devices 12 arranged around the device.

  The linear motion guide device 12 includes a guide rail 13 as a support or a movable element, a spherical rolling element 14, sliders 15A and 15B as a movable element or a support, and the like. A groove 16 is formed along the longitudinal direction of the guide rail 13. This rolling element rolling groove 16 is for guiding the spherical rolling element 14 in the longitudinal direction of the guide rail 13, and when the surface roughness of the spherical rolling element 14 is X μmRa, the surface is X μmRa or more and 0.2 μmRa or less. It has a surface roughness of preferably not less than X μmRa and not more than 0.1 μmRa.

The guide rail 13 is connected to the drive device by a rotatable cam follower. A mounting hole 17 for attaching the electronic component suction head 10 to the guide rail 13 by a set screw (not shown). Are provided, and a notch 18 is provided.
Further, the guide rail 13 is a ceramic material (for example, silicon nitride, zirconia, alumina, silicon carbide, titanium boride, or a composite sintered body obtained by sintering these materials) having a specific strength of 2 × 10 ⁷ mm or more, or 1.7. The flat portion of the guide rail 13 excluding the rolling element rolling groove 16 is formed of cermet or cemented carbide having a specific strength of × 10 ⁷ mm or more, and has a surface roughness of 0.5 μmRa to 0.05 μmRa, It is preferably finished with a surface roughness of 0.3 μmRa to 0.05 μmRa.

The notch 18 is for avoiding interference with a mounting part attached to the electronic component mounting apparatus. The corner 18a of the notch 18 has a curvature radius of 0.1 mm or more and 1 mm or less, preferably 0. It is formed with a radius of curvature of 3 mm or more and 1 mm or less.
The spherical rolling element 14 is made of a steel material such as stainless steel, preferably martensitic stainless steel. A large number of spherical rolling elements 14 are arranged between the side surface of the guide rail 13 and both side portions (also referred to as sleeve portions) of the sliders 15A and 15B facing the side surfaces.

The sliders 15 </ b> A and 15 </ b> B are formed in a gate shape in a cross section perpendicular to the longitudinal direction of the guide rail 13, and the spherical rolling elements 14 are disposed along the rolling element rolling grooves 16 of the guide rail 13 in both side portions. A rolling element circulation path for repeated rolling is formed. Of the sliders 15A and 15B, the slider 15A is fixed to the upper part of the electronic component mounting apparatus main body 19, and the slider 15B is fixed to the lower part of the electronic component mounting apparatus main body 19. Therefore, when the cam follower mechanism as a driving device is rotationally driven by a motor or the like (not shown), the electronic component suction head 10 moves up and down integrally with the guide rail 13.
In this embodiment, any one of Examples 1 to 16 shown in Table 1 and Table 2 can be used as the rail material of the guide rail 13.

In Tables 1 and 2, the guide rail of Example 1 uses a high-strength silicon nitride (specific strength: 3.1 × 10 ⁷ mm) obtained by pressure sintering at 1000 atm or higher as a rail material, and a rail plane. The surface roughness of the portion is 0.3 μmRa, the surface roughness of the rolling element rolling groove 16 is 0.08 μmRa, and the radius of curvature of the corner 18a of the notch 18 is about R = 0.15 mm. In addition, the guide rail of Example 2 uses silicon nitride (specific strength is 2.5 × 10 ⁷ mm) obtained by pressure sintering at about 100 atm as a rail material, and the surface roughness of the rail flat portion is set to 0. 3 μmRa, the surface roughness of the rolling element rolling groove 16 is 0.08 μmRa, and the radius of curvature of the corner 18a of the notch 18 is R = 0.15 mm.

The guide rail of Example 3 uses silicon nitride (specific strength 2.2 × 10 ⁷ mm) obtained under a sintering condition of 10 atm or less as a rail material, and the surface roughness of the rail flat portion is 0.4 μmRa, The surface roughness of the rolling element rolling groove 16 is 0.08 μmRa, and the radius of curvature of the corner 18a of the notch 18 is R = 0.15 mm. The guide rail of Comparative Example 1 uses high-strength silicon nitride (specific strength is 3.1 × 10 ⁷ mm) as a rail material, the surface roughness of the rail flat portion is 0.6 μmRa, and the rolling element rolling grooves 16 The surface roughness is 0.08 μmRa, and the radius of curvature of the corner 18a of the notch 18 is R = 0.15 mm.
The guide rail of Example 4 uses silicon nitride (specific strength: 1.8 × 10 ⁷ mm) sintered at 10 atm or less as a rail material, the surface roughness of the rail flat portion is 0.3 μmRa, and rolling element rolling is performed. The surface roughness of the moving groove 16 is 0.08 μmRa, and the radius of curvature of the corner 18a of the notch 18 is R = 0.15 mm.

The guide rail of Comparative Example 2 uses silicon nitride (specific strength 2.2 × 10 ⁷ mm) obtained under sintering conditions of 10 atm or less as a rail material, and the surface roughness of the rail flat portion is 0.8 μmRa. The surface roughness of the rolling element rolling groove 16 is 0.08 μmRa, and the radius of curvature of the corner 18a of the notch 18 is R = 0.08 mm. In this case, the notch 18 has a shape factor. Is about 6. The guide rail of Comparative Example 3 uses silicon nitride (specific strength 1.8 × 10 ⁷ mm) sintered at 10 atm or less as a rail material, the surface roughness of the flat portion is 0.6 μmRa, and rolling element rolling is performed. The surface roughness of the groove 16 is 0.08 μmRa, the radius of curvature of the corner 18a of the notch 18 is R = 0.15 mm, and the guide rail of Comparative Example 4 is nitrided sintered at 10 atm or less. Silicon (specific strength is 1.8 × 10 ⁷ mm) is used as a rail material, the surface roughness of the flat portion is 0.6 μmRa, the surface roughness of the rolling element rolling groove 16 is 0.25 μmRa, and the notch 18 The radius of curvature of the corner 18a is R = 0.15 mm. The guide rail of Comparative Example 4 uses silicon nitride sintered as a rail material at 10 atm or less, like the guide rail of Comparative Example 3, but the sintering temperature and time are different. Is relatively low and has a specific strength of about 1.8 × 10 ⁷ mm.

Moreover, it is as follows when the raw material used for Examples 5-17 and Comparative Examples 5 and 6 is shown collectively.
(1) Carbide system 1 (WC-Co system G1, manufactured by Nippon Tungsten Co., Ltd., specific strength; 1.23 × 10 ⁷ mm)
(2) Carbide system 2 (WC-Co system G3 manufactured by Nippon Tungsten Co., Ltd., specific strength: 1.77 × 10 ⁷ mm)
(3) Carbide type 3 (WC-Ni-Cr type NM15 manufactured by Nippon Tungsten Co., Ltd., specific strength; 2.35 × 10 ⁷ mm)
(4) Carbide system 4 (WC-Ni-Cr-Mo system NR11 manufactured by Nippon Tungsten Co., Ltd., specific strength; 1.78 × 10 ⁷ mm)
(5) Carbide system 5 (WC-TiC-TaC system RCCL manufactured by Nippon Tungsten Co., Ltd., specific strength; 0.68 × 10 ⁷ mm)

(6) Carbide system 6 (WC-Ni system DN manufactured by Daijet Industries, specific strength; 1.47 × 10 ⁷ mm)
(7) Carbide system 7 (WC-Ni-Cr system M61U, manufactured by Sumitomo Electric Industries, Ltd., specific strength: 1.95 × 10 ⁷ mm)
(8) Cermet 1 (TiC-TaN-Ni-Mo DUX40 manufactured by Nippon Tungsten Co., Ltd., specific strength: 2.73 × 10 ⁷ mm)
(9) Cermet system 2 (TiC-TaN-Ni-Mo system DUX30 manufactured by Nippon Tungsten Co., Ltd., specific strength; 2.46 × 10 ⁷ mm)
(10) Cermet system 3 (Boride system UD-II35T manufactured by Asahi Glass Co., Ltd., specific strength; 2.23 × 10 ⁷ mm)
(11) Cermet system 4 (Boride system UD-II50T manufactured by Asahi Glass Co., Ltd., specific strength; 2.55 × 10 ⁷ mm)
The bending strength is a value measured based on JIS R1601.

  The present inventors performed a load test as shown in FIG. 2 for the guide rails of Examples 1 to 17 and Comparative Examples 1 to 6 shown in Tables 1 and 2. That is, a load imitating the weight of the head was applied to the other end of the guide rail with one end fixed, and the stress value when the rail material was broken by the applied load was measured. The measurement results at this time are shown in FIGS. The measurement results in FIG. 3 and FIG. 4 show the maximum stress on the rail calculated by numerical calculation assuming that an actual machine gun type electronic component mounting machine is driven at a maximum speed of 0.2 seconds per cycle. The value obtained by multiplying the safety factor is standardized as 1.

As shown in FIGS. 3 and 4, the guide rail of the example has a strength of about 1.1 to 1.8 times that of the comparative example, and exceeds the reference stress.
Further, the above-described load test was performed on the guide rail 13 prepared by using the material of the cermet system 1 and changing the surface roughness of the flat portion. The measurement result at this time is shown in FIG. As FIG. 5 shows, when the surface roughness of a plane part is in the range of the present invention, it exceeds the above-mentioned standard stress.

  In addition, the present inventors conducted a linear motion test for 10 hours in a state in which one cycle is 0.2 seconds, the rolling element preload is 60 N, and a pseudo bending moment is applied to the two rails via springs. It performed with respect to the guide rail of Example 1 and Comparative Example 4, and measured the amount of preload loss of each rail after the test. The test results are shown in Table 3. The test results in Table 3 show the preload loss amount of Comparative Example 4 as 1.

  FIG. 15 shows a testing machine simulating a component mounting apparatus. Using this testing machine, a spring (spring load: 100 N) is applied to two guide rails 13 with a stroke of 80 mm and a cycle of 0.2 seconds. A linear motion test for 20 hours in a state in which a bending moment is applied via the test is performed on Examples 18 to 20 and Comparative Examples 7 and 8, and the preload loss amount of each Example and Comparative Example after the test is performed. Was measured. The test results are shown in Table 4. The test results in Table 4 are shown as relative values with the preload loss amount of Comparative Example 7 as 1. The silicon nitride sphere used for the rolling element in this embodiment was formed of EC141 silicon nitride manufactured by Nippon Special Ceramics Co., Ltd.

As shown in Table 3, in the guide rail of Example 1 in which the surface roughness of the rolling element rolling groove 16 is 0.08 μmRa, Comparative Example 4 in which the surface roughness of the rolling element rolling groove 16 is 0.25 μmRa. In comparison with the above, the amount of change in the preload of the rolling element 14 was small, and the damage to the rolling element 14 was slight. Here, the preload change is caused by the wear (reduction in diameter) of the rolling elements 14.
As described above, in this embodiment, the guide rail 13 is formed of a ceramic material having a specific strength of 2 × 10 ⁷ mm or more, or a cermet or cemented carbide having a specific strength of 1.7 × 10 ⁷ mm or more. In some cases, even when the electronic component suction head 10 moves up and down at a high speed of 0.2 seconds or less or revolves by being attached to a drum, it is sufficient for the inertial force generated by acceleration, head weight, etc. A guide rail having high strength can be obtained.

  In the present embodiment, the surface of the guide rail 13 is obtained by finishing the flat portion of the guide rail 13 with a surface roughness of 0.5 μmRa to 0.05 μmRa, preferably 0.3 μmRa to 0.05 μmRa. Stress concentration due to unevenness is reduced. Therefore, it is possible to obtain a guide rail having a sufficient strength against the inertia force generated by the weight of the guide rail 13 or the weight of the head 10, and the guide rail when the electronic component suction head 10 is moved up and down at high speed. 13 can be suppressed.

  Furthermore, in this embodiment, when the corner 18a of the notch 18 provided on the guide rail 13 is formed with a radius of curvature of 0.1 mm to 1 mm, preferably 0.3 mm to 1 mm. The stress concentration on the corner 18a due to the inertial force is reduced. Therefore, even when the notch 18 for avoiding interference with the component is provided in the guide rail 13, the electronic component suction head 10 can be moved up and down more accurately and at high speed.

In this embodiment, when the surface roughness of the rolling element rolling groove 16 is 0.2 μmRa or less, preferably 0.1 μmRa or less, the guide rail 13 is formed of a ceramic material such as silicon nitride. Even when it exists, the surface roughening and abrasion of the rolling element 14 can be prevented more effectively.
Moreover, the cermet or cemented carbide used for the rail of the present invention is not particularly limited, and the materials described above can be used.
Next, Examples A1 to A4 and Comparative Examples a1 to a3 of the present invention are shown in Table 5.

In Table 5, Example A1 is a high-strength silicon nitride obtained by pressure-sintering the guide rail 13 of FIG. 1 at about 1000 atm (specific strength: 3.2 × 10 ⁷ mm, planar portion roughness Ra: 0.00). A diamond-like carbon film (hereinafter abbreviated as DLC film) having a film thickness of 2 μm and a surface roughness of 0.01 μm Ra is formed on the surface of the rolling element 14 made of SUS440C. The linear motion guide device covers the surface of the moving body 14. In Example A2, the guide rail 13 is formed from silicon nitride (specific strength: 2.6 × 10 ⁷ mm, flat surface roughness Ra: 0.3 μm) obtained by pressure sintering at about 1000 atmospheres, and SUS440C. Example A3 is a linear motion guide device in which a TiAlN film (film thickness: 2 μm, surface roughness: 0.05 μm Ra) is formed on the surface of the rolling element 14 and the surface of the rolling element 14 is covered with this TiAlN film. The surface of the rolling element 14 made of SUS440C, in which the guide rail 13 is formed from silicon nitride (specific strength: 2.1 × 10 ⁷ mm, flat surface roughness Ra: 0.3 μm) obtained under sintering conditions of about 8 atm. This is a linear motion guide device in which a CrN film (film thickness: 3 μm, surface roughness: 0.03 μm Ra) is formed and the surface of the rolling element 14 is covered with this CrN film. In Example A4, the guide rail 13 is made of silicon nitride (specific strength: 1.5 × 10 ⁷ mm, flat surface roughness Ra: 0.3 μm) obtained under sintering conditions of about 8 atm and made of SUS440C. In this linear motion guide device, a diamond-like carbon film having a film thickness of 2 μm and a surface roughness of 0.01 μm Ra is formed on the surface of the rolling element 14, and the surface of the rolling element 4 is covered with this DLC film.

On the other hand, Comparative Example a1 is a linear motion guide in which the guide rail 13 is formed from silicon nitride (specific strength: 1.5 × 10 ⁷ mm, flat surface roughness Ra: 0.6 μm) obtained under sintering conditions of about 8 atmospheres. A hard coating such as a DLC coating is not formed on the surface of the rolling element of Comparative Example a1. In Comparative Example a2, the guide rail 13 is formed from silicon nitride (specific strength: 2.1 × 10 ⁷ mm, flat surface roughness Ra: 0.6 μm) obtained under sintering conditions of about 8 atmospheres, and from SUS440C. A rolling guide device in which a TiN film (film thickness: 3 μm, surface roughness: 0.1 μm Ra) is formed on the surface of the rolling element 14 and the surface of the rolling element 14 is coated with this TiN film, Comparative Example a3 is The surface of the rolling element 14 made of SUS440C while the guide rail 13 is formed from silicon nitride (specific strength: 2.1 × 10 ⁷ mm, flat surface roughness Ra: 0.6 μm) obtained under sintering conditions of about 8 atm. This is a linear motion guide device in which a CrN film (film thickness: 10 μm, surface roughness: 0.05 μm Ra) is formed and the surface of the rolling element 14 is covered with this CrN film. The rail material of Comparative Example a1 has a non-uniform internal structure.

  For Examples A1 to A4 and Comparative Examples a1 to a3 shown in Table 5, the cycle was set to 50 seconds with a preload of 60 N and a pseudo bending moment applied to the two guide rails via springs. The operation was continued for hours. After the test, the preload loss amount of each guide rail was measured, and the wear amount of the rolling element surface was estimated based on the measured value, and the durability of Examples A1 to A4 and Comparative Examples a1 to a3 was evaluated. The evaluation results are also shown in Table 5. The durability in Table 5 is shown as a relative value with the preload loss amount of Comparative Example a2 as 1.

As shown in Table 5, each of the linear motion guide devices of Examples A1 to A3 has a durability that is about 50 to 150 times higher than that of Comparative Example a1. This is because in Comparative Example a1, the guide rail is formed of silicon nitride having a low specific strength and the planar portion roughness is large, whereas in Examples A1 to A3, the guide rail has a high specific strength of 2 × 10 ⁷ mm or more. This is because it is made of high silicon nitride having a low planar portion roughness and the wear resistance of the rolling elements is improved by the hard coating.

  Moreover, each linear motion guide apparatus of Example A1-A3 has shown the high value of about 5 to 15 times the durability compared with the thing of the comparative example a2. This is because Comparative Example a2 has a surface roughness of 0.1 μmRa of a hard coating such as TiN formed on the surface of the rolling element, while Examples A1 to A3 have DLC formed on the surface of the rolling element, This is because the surface roughness of the hard coating of CrN is 0.05 μmRa or less.

In addition, the linear motion guide device of Example A4 has a relatively high durability value of 2.5 times that of Comparative Example a1. This is because the flatness of the flat portion of the guide rail is small, the stress concentration caused by minute irregularities on the surface of the guide rail is reduced, and DLC (diamond-like carbon) is formed on the surface of the rolling element, thereby improving the wear resistance. It is.
FIG. 6 shows the result of examining the correlation between the film thickness of a hard film (surface roughness: 0.01 μmRa) such as DLC formed on the surface of the rolling element and the durability of the linear motion guide device. The guide rail of the linear motion guide device used here is made of silicon nitride (specific strength: 2.6 × 10 ⁷ mm, flat surface roughness: 0.3 μm) obtained by pressure sintering at about 100 atm. Is formed. In addition, the durability on the vertical axis in the figure is shown as a relative value with the preload loss amount of Comparative Example a2 as 1.

  As shown in FIG. 6, when the thickness of the hard coating formed on the surface of the rolling element is out of the range of 0.1 to 5 μm, the durability of the linear motion guide device is drastically lowered. This is because when the thickness of the hard coating formed on the surface of the rolling element is out of the range of 0.1 μm to 5 μm, the hard coating is easily peeled off or dropped off. This is probably because abnormal wear such as chipping occurs on the surface of the groove or rolling element. Therefore, when a hard film such as DLC is formed on the surface of the rolling element and the surface of the rolling element is covered with this hard film, the film thickness of the hard film is 0.1 μm to 5 μm, preferably 0.2 μm to 5 μm. It is desirable to be within the range.

Next, FIG. 7 shows the result of examining the correlation between the surface roughness of the hard coating (film thickness: 2 μm) formed on the surface of the rolling element and the durability of the linear motion guide device. In addition, the guide rail of the linear motion guide device used here is silicon nitride obtained by pressure sintering of about 100 atm (specific strength: 2.6 × 10 ⁷ mm, flat surface roughness Ra: 0.3 μm). Formed from.

As shown in FIG. 7, when the surface roughness of the hard coating formed on the surface of the rolling element exceeds 0.05 μmRa, the durability of the linear motion guide device sharply decreases. This is because when the surface roughness of the hard coating formed on the surface of the rolling element exceeds 0.05 μmRa, the surface of the hard coating locally contacts the rolling element rolling groove of the guide rail, and the contact stress at this portion This is considered to be because chipping or the like occurs on the surface of the rolling element rolling groove due to the increase in the rolling speed, and the rolling element rolling groove of the guide rail wears out early. Accordingly, when a hard film such as DLC or CrN is formed on the surface of the rolling element and the surface of the rolling element is covered with this hard film, the surface roughness of the hard film is 0.05 μmRa or less, preferably 0.02 μmRa. The following is desirable.
Next, Table 6 shows Examples B1 to B15 and Comparative Examples b1 to b6 of the present invention.

In Table 6, the rolling element materials used in Examples B1 to B15 and Comparative Examples b1 to b6 are collectively shown as follows.
(1) Silicon nitride 1b (NPN-3 manufactured by Nippon Tungsten Co., Ltd .; Hv = 1850)
(2) Silicon nitride type 2b (Shinagawa White Brick Co., Ltd. SAN-P; Hv = 1700)
(3) Zirconia 1b (NPZ-1 manufactured by Nippon Tungsten Co., Ltd .; Hv = 1250)
(4) Zirconia 2b (KGS20 manufactured by Nippon Special Ceramics Co., Ltd .; Hv = 1300)
(5) Zirconia 3b (Kyocera Corporation Z703N; Hv = 1350)
(6) Zirconia 4b (NPZ-3 manufactured by Nippon Tungsten Co., Ltd .; Hv = 1650)

(7) Alumina-based 1b (AZ-93 manufactured by Saint-Gobain Norton; Hv = 1600)
(8) Alumina-based 2b (NPA-2 manufactured by Nippon Tungsten Co., Ltd .; Hv = 2000)
(9) Carbide 1b (WC-Ni-Cr alloy (NM18 manufactured by Nippon Tungsten Co., Ltd.); Hv = 1050)
(10) Carbide 2b (WC-Co alloy (GTi05 manufactured by Mitsubishi Materials Corporation); Hv = 1550)
(11) Carbide 3b (WC-TiC-TaC-Co alloy (SN10 manufactured by Nippon Tungsten Co., Ltd.); Hv = 1700)
(12) Carbide 4b (WC-Co alloy (UF30 manufactured by Nippon Tungsten Co., Ltd.); Hv = 1500)

(13) Cermet type 1b (TiC-TaN-Ni-Mo type alloy (DUX30 manufactured by Nippon Tungsten Co., Ltd.); Hv = 1700)
(14) Titanium-based sintered alloy 1b (Ti-W-Co-based alloy (TW-3, manufactured by Nippon Tungsten Co., Ltd.); Hv = 1000)
(15) SUS440C (Hv = 1000)
(16) SKH4 (Hv = 750)
(17) Carbide 5b (GTi40C manufactured by Mitsubishi Materials Corporation; Hv = 760)
(18) Carbide 6b (GTi30C manufactured by Mitsubishi Materials Corporation; Hv = 880)
(19) Silicon carbide type 1b (TSC-1 manufactured by Toshiba Corporation; Hv = 2400)
(20) Silicon carbide-based 2b (Nippon Choshi Co., Ltd. SC-20; Hv = 2860)

In order to evaluate the durability as a linear motion guide device, a rolling element was manufactured from the above raw materials, and the linear motion guide device shown in FIG. 1 was manufactured. The surface roughness of the rolling elements is 0.025 μmRa in any case. As the rail material, four types of silicon nitrides 1 to 4 shown in Table 6 were used. Here, silicon nitride 1 is high-strength silicon nitride (specific strength: 3.2 × 10 ⁷ mm, hardness: Hv1700) obtained by pressure sintering at about 1000 atmospheres, and silicon nitride 2 is pressurized at about 100 atmospheres. Silicon nitride obtained by sintering (specific strength: 2.6 × 10 ⁷ mm, hardness: Hv1500), silicon nitride 3 is silicon nitride obtained under sintering conditions of about 8 atm (specific strength: 2.1 × 10 ⁷ mm, hardness: Hv 1400). Silicon nitride 4 is silicon nitride having a non-uniform internal structure, low strength, a specific strength of 1.5 × 10 ⁷ mm, and a hardness of Hv1200.

  For Examples B1 to B15 shown in Table 6 (plane portion roughness Ra is 0.3 μm) and comparative examples b1 to b6 (plane portion roughness Ra is 0.6 μm), one cycle is 0. A continuous operation for 50 hours was performed with a preload of 60 N for 2 seconds and a pseudo bending moment applied to the two guide rails via a spring. After the test, the preload loss amount of each guide rail was measured, and the wear amount of the rolling element surface was estimated based on the measured value, and the durability of Examples B1 to B14 and Comparative Examples b1 to b6 was evaluated. The evaluation results are also shown in Table 6. The durability in Table 6 is shown as a relative value with the preload loss amount of Comparative Example b1 as 1.

As shown in Table 6, each of the linear motion guide devices of Examples B1 to B14 has a durability that is about 5 to 15 times higher than that of Comparative Example b1. This is because in Comparative Example b1, the guide rail is made of silicon nitride having a low specific strength and the planar portion roughness Ra is large, while in Examples A1 to A3, the guide rail has a high ratio of 2 × 10 ⁷ mm or more. This is because it is formed of silicon nitride having strength and has a small planar portion roughness Ra.

Moreover, each linear motion guide apparatus of Examples B1-B14 has shown the high value of about 3 to 10 times as compared with the thing of the comparative example b2. This is because Comparative Example b2 has a hardness ratio between the rolling element and the guide rail (rolling element / guide rail) of 0.54, whereas Examples A1 to A3 have a hardness ratio between the rolling element and the guide rail. This is because is 0.6 or more.
Further, each of the linear motion guide devices of Examples B1 to B14 shows a high value of about 6 to 18 times as long as that of Comparative Example b5. In Comparative Example b5, the hardness ratio between the rolling element and the guide rail is 1.6, whereas in Examples A1 to A3, the hardness ratio between the rolling element and the guide rail is 1.5 or less. This is because.

The linear motion guide device of Example B15 shows a relatively high value of the durability of three times that of Comparative Example b3. This is because the flatness of the flat portion of the guide rail is small, the stress concentration generated in the minute irregularities on the surface of the guide rail is reduced, and the guide rail has a strength capable of withstanding the inertial force.
FIG. 8 shows the result of examining the correlation between the hardness ratio between the rolling elements and the guide rail and the durability of the linear motion guide device. Here, the durability of the linear motion guide device was tested using a guide rail made of silicon nitride (specific strength: 2.6 × 10 ⁷ mm) obtained by pressure sintering at about 100 atm. In any case, the planar portion roughness of the guide rail is 0.3 μm. Further, the durability on the vertical axis in the figure is shown as a relative value with the preload loss amount of Comparative Example b1 as 1.

As shown in FIG. 8, when the ratio between the surface hardness of the rolling element and the surface hardness of the guide rail is out of the range of 0.6 to 1.5, the durability of the linear motion guide device is drastically lowered. This is considered to be because wear of the guide rail and the rolling element is promoted when the ratio between the surface hardness of the rolling element and the surface hardness of the guide rail is out of the range of 0.6 to 1.5. Therefore, in order to prevent the durability of the linear motion guide device from deteriorating, the surface hardness of the rolling element may be in the range of 0.6 to 1.5 times the hardness of the guide rail.
Next, Table 7 shows Examples C1 to C3 and Comparative Examples c1 to c3 of the present invention.

In Table 7, Examples C1 to C3 are obtained by forming a dense nitride film of Hv800 to Hv1400 on the entire surface of the rolling element by the following heat treatment method. If the surface hardness of the nitride film is Hv800 or more, nitriding is performed. The method for forming the film is not particularly limited. For example, methods such as gas soft nitriding, ion nitriding, salt bath nitrosulphurizing, gas nitrosulphurizing other than heat treatment conditions 1, 2, and 3 can be used. In Examples C1 to C3, nitrogen (N) is diffused and permeated on the surface of the rolling element made of SUS440C, so that (Fe, Cr) _{2 to 3 or 4} N, Cr ₂ N, Mo ₂ N, A dense nitride film such as VN is formed.

The heat treatment conditions 1 to 3 in Table 7 are as follows.
<Heat treatment condition 1>
480 ° C. to 560 ° C. × 3 to 8 hours nitriding treatment (50% N ₂ -50% NH ₃ mixed gas)
<Heat treatment condition 2>
300 ° C. to 380 ° C. × 1 hour fluorination treatment (90% N ₂ -10% NF ₃ mixed gas), then 400 ° C. to 480 ° C. × 24 to 48 hours nitriding treatment (50% N ₂ -50% NH ₃ mixed gas) )
<Heat treatment condition 3>
Soft nitriding treatment (salt bath nitriding mainly composed of cyanate (KCNO and NaCNO)) at 480 ° C to 560 ° C for 3 to 8 hours

  Heat treatment condition 1 is an example of gas nitriding. The heat treatment condition 2 is an example in the case where a fluorination treatment is performed as a pretreatment, and the surface oxide layer that inhibits nitriding is removed by the cleaning action of the fluorine-based gas, so that a uniform nitride film is formed at a lower temperature. This is a particularly effective technique for high alloy systems. Heat treatment condition 3 is an example of soft nitriding.

In Example C1, the guide rail 13 shown in FIG. 1 is made of high-strength silicon nitride (specific strength: 3.3 × 10 ⁷ mm) obtained by pressure sintering at about 1200 atm, and the surface of the rolling element 14 made of SUS440C. In this linear motion guide device, a nitride film (surface hardness: Hv1100, surface roughness: 0.04 μmRa) is formed, and the surface of the rolling element 14 is covered with this nitride film. In Example C2, the guide rail 13 is formed of high-strength silicon nitride (specific strength: 2.7 × 10 ⁷ mm) obtained by pressure sintering at about 150 atm, and on the surface of the rolling element 14 made of SUS440C. This is a linear guide device in which a nitride film (surface hardness: Hv1360, surface roughness: 0.05 μmRa) is formed and the surface of the rolling element 14 is covered with this nitride film. A nitride film (surface hardness: Hv950, surface roughness: 0) is formed on the surface of the rolling element 14 made of SUS440C and formed from silicon nitride (specific strength: 2.2 × 10 ⁷ mm) obtained under a certain sintering condition. .03 μmRa), and the surface of the rolling element 14 is covered with this nitride film. The planar portion roughness Ra of the guide rail 13 used in Examples C1, C2, and C3 is 0.3 μm.

On the other hand, Comparative Example c1 is a linear motion guide device in which the guide rail is formed of silicon nitride having a specific strength of 1.5 × 10 ⁷ mm. The rolling element of this Comparative Example c1 (surface hardness: Hv700, surface roughness: A nitride film is not formed on the surface of 0.05 μm Ra). Comparative example c2 is a linear motion guide device in which the guide rail is formed of silicon nitride having a specific strength of 2.7 × 10 ⁷ mm. The rolling element of this comparative example c2 (surface hardness: Hv710, surface roughness: A nitride film is not formed on the surface of 0.06 μm Ra). Further, Comparative Example c3 is a linear motion guide device in which the guide rail is made of silicon nitride having a specific strength of 2.2 × 10 ⁷ mm. The surface roughness of the rolling element of Comparative Example c3 is 0. A 07Ra nitride film (surface hardness: Hv1430) is formed. The planar portion roughness Ra of the guide rail 13 used in Comparative Examples c1, c2, and c3 is 0.6 μm.

  For Examples C1 to C3 and Comparative Examples c1 to c3, one cycle was 0.2 seconds, preload was 55 N, and 8 hours of continuous operation was performed with a pseudo bending moment applied to the two rails via springs. It was. After the test, the amount of decrease in the frictional resistance of each rail was measured, and the amount of wear of the rolling elements was evaluated. The evaluation results are shown in Table 8. Note that the amount of decrease in frictional resistance shown in Table 8 is shown as a relative value with the amount of decrease in frictional resistance of Comparative Example c1 as 1.

As shown in Table 8, in Examples C1 to C3, compared with Comparative Examples c1 to c3, the amount of decrease in frictional resistance before and after the test was small, and the rolling elements were slightly damaged. Here, the reduction in frictional resistance is caused by wear of the rolling elements or rails.
In addition, each of the linear motion guide devices of Examples C1 to C3 shows an extremely low value of the amount of wear of the rolling elements of about 14/1000 to 29/1000 as compared with that of Comparative Example c1. This is because the comparative example c1 is made of silicon nitride having a low specific strength and has a large flat surface roughness Ra, while the examples C1 to C3 have a high ratio in which the guide rail is 2 × 10 ⁷ mm or more. This is because it is made of high-strength silicon nitride, has a small flat surface roughness Ra, and improves the wear resistance of the rolling elements by the nitride film.

In addition, each of the linear motion guide devices of Examples C1 to C3 shows a low value of about 7/100 to 145/1000 in the amount of wear of the rolling elements as compared with that of Comparative Example c2. This is because Comparative Example c2 does not have a nitride film formed on the surface of the rolling element, whereas Examples C1 to C3 have a nitride film formed on the surface of the rolling element, resulting in improved wear resistance.
Further, each of the linear motion guide devices of Examples C1 to C3 shows a lower value of the amount of wear of the rolling elements than that of Comparative Example c3. This is because Comparative Example c3 had a surface hardness and surface roughness of the nitride film formed on the surface of the rolling element of Hv1430, 0.07 μmRa, while Examples C1 to C3 were formed on the surface of the rolling element. This is because the surface hardness of the nitride film is in the range of Hv800 to Hv1400, and the surface roughness of the nitride film is 0.05 μmRa or less.

FIG. 9 shows the results of examining the correlation between the surface hardness of the nitride film (surface roughness: 0.03 μm Ra) formed on the surface of the rolling element and the amount of reduction in the frictional resistance of the guide rail. In addition, the guide rail of the linear motion guide device used here is formed of silicon nitride (specific strength: 3.3 × 10 ⁷ mm) obtained by pressure sintering of about 1200 atm, and the planar portion roughness Ra is 0.3 μm.

As shown in FIG. 9, it can be seen that when the surface hardness of the nitride film formed on the surface of the rolling element deviates from the range of Hv800 to Hv1400, the wear of the rolling element or rail is rapidly accelerated. This is because, when the surface hardness of the nitride film is less than Hv 800, the hardness difference from the rail material is increased to promote wear of the rolling elements, and when the surface hardness of the nitride film exceeds Hv 1400, the surface of the nitride film This is because Fe ₂ N is formed on the surface and the surface of the rolling element becomes brittle.

Next, FIG. 10 shows the results of examining the correlation between the surface roughness of the nitride film (surface hardness: Hv1350) formed on the surface of the rolling element and the amount of decrease in the frictional resistance of the guide rail. In addition, the guide rail of the linear motion guide device used here is formed of silicon nitride (specific strength: 3.3 × 10 ⁷ mm) obtained by pressure sintering of about 1200 atm, and the planar portion roughness Ra is 0.3 μm.

  As shown in FIG. 10, it can be seen that when the surface roughness of the nitride film formed on the surface of the rolling element exceeds 0.05 μmRa, the rolling element and the guide rail are abruptly worn. This is because when the surface roughness of the nitride film exceeds 0.05 μmRa, the minute irregularities on the surface of the rolling element are likely to be in direct contact with the surface of the rolling element rolling groove, and the minute irregularities on the surface of the rolling element cause the rolling element rolling groove to This is because the surface is damaged or the wear of the rolling element rolling groove surface is promoted.

As the ceramic used for the guide rail, for example, silicon nitride, zirconia, alumina, silicon carbide, titanium boride and the like can be used, and these composite sintered bodies can be used, among which silicon nitride is It is particularly preferable because of its high rigidity and high fracture toughness value. In this case, if the fracture toughness value of the silicon nitride material is 5 MPa · m ^0.5 or more and the hardness of the silicon nitride material is 14 GPa or more, the fracture strength can be further suitably used.

Silicon nitride can be obtained, for example, by pressure sintering such as HIP method, gas pressure sintering method, etc., and columnar crystals grown into columnar shapes having an average width of 3 μm or less and a length of 4 μm or more are 70 or more of the entire silicon nitride grains. However, it is preferably 90% or more, but any material that satisfies the condition of specific strength may be sintered under normal pressure. The auxiliary component can be selected from metal oxides such as Al ₂ O ₃ , MgO and CeO and rare earth oxides such as Y ₂ O ₃ , Yb ₂ O ₃ and La ₂ O _3. In addition, it is possible to use one added with an upper limit of 20 wt% of the entire sintered body. Further, if defects such as vacancies and foreign matters inside the material are 50 μm or less, preferably 20 μm or less in terms of the equivalent circle diameter, local material strength deterioration is suppressed, so that the reliability of the material can be improved. .
Next, Table 9 shows Examples D1 to D3 and Comparative Examples d1 to d3 of the present invention.

In Table 9, in Example D1, the guide rail 13 shown in FIG. 1 is formed from high-strength silicon nitride (specific strength: 3.3 × 10 ⁷ mm) obtained by pressure sintering at about 1200 atm and SUS440C. A linear guide that forms a composite carbide layer (surface hardness: Hv1640, surface roughness: 0.03 μmRa) containing Cr carbide and C on the surface of the moving body 14 and covers the surface of the rolling element 14 with the composite carbide layer. Device. In Example D2, the guide rail 13 is formed of high-strength silicon nitride (specific strength: 2.7 × 10 ⁷ mm) obtained by pressure sintering at about 150 atm, and is formed on the surface of the rolling element 14 made of SUS440C. A linear motion guide device in which a composite carbide layer (surface hardness: Hv1560, surface roughness: 0.05 μmRa) containing Cr carbide and C is formed, and the surface of the rolling element 14 is covered with this composite carbide layer. In Example D3, the guide rail 13 is formed of silicon nitride (specific strength: 2.2 × 10 ⁷ mm) obtained under sintering conditions of about 10 atmospheres, and Cr carbide and C are formed on the surface of the rolling element 14 made of SUS440C. Is a linear motion guide device in which a composite carbide layer (surface hardness: Hv1720, surface roughness: 0.04 μmRa) is formed and the surface of the rolling element 14 is covered with this composite carbide layer. The planar portion roughness Ra of the guide rail 13 used in Examples D1, D2, and D3 is 0.3 μm.

On the other hand, Comparative Example d1 is a linear motion guide device in which the guide rail is made of silicon nitride having a specific strength of 1.5 × 10 ⁷ mm. The rolling element of this Comparative Example d1 (surface hardness: Hv700, surface roughness: A composite carbide layer is not formed on the surface of 0.05 μm Ra). Comparative example d2 is a linear motion guide device in which the guide rail is formed of silicon nitride having a specific strength of 2.7 × 10 ⁷ mm. The rolling element of this comparative example d2 (surface hardness: Hv710, surface roughness: No composite carbide layer is formed on the surface of 0.05 μm Ra). Further, Comparative Example d3 is a linear motion guide device in which the guide rail is formed of silicon nitride having a specific strength of 2.2 × 10 ⁷ mm. The surface roughness of the rolling element of Comparative Example d3 is 0. A 1 μm Ra composite carbide layer (surface hardness: Hv1750) is formed. The planar portion surface roughness Ra of the guide rail used in Comparative Examples d1, d2 and d3 is 0.6 μm. The composite carbide layer can uniformly form a composite carbide layer made of Fe, Cr, and C over the entire Cr diffusion layer by diffusing and infiltrating Cr on the surface of the rolling element. This Cr diffusion and penetration treatment is not particularly limited. An example of Cr diffusion and carburization is the use of a semi-sealed container made of steel plate, 65 wt% to 80 wt% metal Cr powder, 19 wt% to 34 wt% Al ₂ O ₃ powder, 0.5 wt% to 1.0 wt%. For example, there is a method in which an object to be processed is embedded in a mixed powder composed of% NH ₄ C and heated at 950 ° C. to 1150 ° C. for 5 to 15 hours while flowing H ₂ gas. According to this method, the high hardness Cr carbide (Cr ₂₃ C ₆ , Cr ₇ C ₆ , Cr ₂ C) contained in the chromium diffusion hard layer is imparted to the object to be processed so as to provide a stable surface hardened layer that does not peel off. Can do. Further, the base material is preferably a steel material (for example, stainless steel, SUJ2 or the like) having a strength after tempering of HRC58 or higher.

  For Examples D1 to D3 and Comparative Examples d1 to d3, one cycle was 0.2 seconds, preload was 55 N, and continuous operation was performed for 8 hours with a bending moment applied to the two rails via a spring. It was. After the test, the amount of decrease in the frictional resistance of each rail was measured, and the amount of wear of the rolling elements was evaluated. The evaluation results are shown in Table 10. Note that the amount of decrease in frictional resistance shown in Table 10 is expressed as a relative value with the amount of decrease in frictional resistance of Comparative Example d1 as 1.

As shown in Table 10, the linear motion guide devices of Examples D1 to D3 show extremely low values of about 1/250 to 2/250 of the amount of wear of the rolling elements as compared with that of Comparative Example d1. ing. This is because the comparative example d1 is made of silicon nitride having a low specific strength and has a large flat surface roughness Ra, while the examples D1 to D3 have a high ratio in which the guide rail is 2 × 10 ⁷ mm or more. This is because it is made of high-strength silicon nitride, has a small flat surface roughness Ra, and has improved wear resistance due to the composite carbide layer.

Moreover, each linear motion guide apparatus of Examples D1-D3 has shown the value with a low amount of wear of a rolling element compared with the thing of the comparative example d2. This is because the composite carbide layer is not formed on the surface of the rolling element in Comparative Example d2, whereas the composite carbide layer is formed on the surface of the rolling element in Examples D1 to D3.
Further, each of the linear motion guide devices of Examples D1 to D3 shows a lower value of the wear amount of the rolling elements than that of Comparative Example d3. This is because Comparative Example d3 has a surface hardness and surface roughness of the composite carbide layer formed on the surface of the rolling element of Hv1750 and 0.1 μmRa, while Examples C1 to C3 are formed on the surface of the rolling element. This is because the surface hardness of the composite carbide layer is in the range of Hv1000 to Hv1800, and the surface roughness of the composite carbide layer is 0.05 μmRa or less.

FIG. 11 shows the result of examining the correlation between the surface hardness of the composite carbide layer formed on the surface of the rolling element and the amount of decrease in the frictional resistance of the guide rail. In addition, the guide rail of the linear guide apparatus used here is formed from silicon nitride (specific strength: 3.3 × 10 ⁷ mm) obtained by pressure sintering at about 1200 atm.
As shown in FIG. 11, when the surface hardness of the composite carbide layer formed on the surface of the rolling element is out of the range of Hv1000 to Hv1800, the wear amount of the guide rail or the rolling element increases rapidly. This is because, when the surface hardness of the composite carbide layer is less than Hv1000, the wear of the rolling element is promoted by increasing the hardness difference from the rail material, and when the surface hardness of the composite carbide layer exceeds Hv1800, the rolling element This is because the carbide layer formed on the surface of the steel becomes brittle.

Next, FIG. 12 shows the result of examining the correlation between the surface roughness of the composite carbide layer formed on the surface of the rolling element and the amount of reduction in the frictional resistance of the guide rail. In addition, the guide rail of the linear guide apparatus used here is formed from silicon nitride (specific strength: 3.3 × 10 ⁷ mm) obtained by pressure sintering at about 1200 atm.
As shown in FIG. 12, when the surface roughness of the composite carbide layer formed on the surface of the rolling element exceeds 0.05 μmRa, the wear amount of the guide rail or the rolling element increases rapidly. This is because, when the surface roughness of the composite carbide layer exceeds 0.05 μmRa, the minute irregularities on the surface of the rolling element are likely to be in direct contact with the surface of the rolling element rolling groove, and the surface of the rolling element rolling groove is caused by the composite carbide layer. This is because they are damaged or wear is promoted.

As the ceramic used for the guide rail, for example, silicon nitride, zirconia, alumina, silicon carbide, titanium boride, etc. can be used, and these composite sintered bodies can be used, among which silicon nitride Is particularly preferred because of its high rigidity and high fracture toughness. At this time, if the fracture toughness value of the silicon nitride material is 5 MPa · m ^0.5 or more and the hardness of the silicon nitride material is 14 GPa or more, the fracture strength can be further suitably used.
Next, Examples E1 to E3 and Comparative Examples e1 to e3 of the present invention are shown in Table 11.

In Table 11, in Example E1, the guide rail 13 of FIG. 1 is formed from high-strength silicon nitride (specific strength: 3.3 × 10 ⁷ mm) obtained by pressure sintering at about 1200 atmospheres, and SUS440C is used. This is a linear motion guide device in which a boride film (surface hardness: Hv1530, surface roughness: 0.04 μmRa) is formed on the surface of the moving body 14, and the surface of the rolling element 14 is covered with this boride film. In Example E2, the guide rail 13 is formed from high-strength silicon nitride (specific strength: 2.7 × 10 ⁷ mm) obtained by pressure sintering at about 150 atm. On the surface of the rolling element 14 made of SUS440C. A boring film (surface hardness: Hv 1460, surface roughness: 0.05 μm Ra) is a linear motion guide device in which the surface of the rolling element 14 is covered with this boride film. A boride film (surface hardness: Hv1640, surface roughness) is formed on the surface of the rolling element 14 made of SUS440C and formed from silicon nitride (specific strength: 2.2 × 10 ⁷ mm) obtained under sintering conditions of about 10 atm. This is a linear motion guide device in which the surface of the rolling element 14 is covered with this boride film. The planar portion roughness Ra of the guide rail 13 used in Examples E1 to E3 is 0.3 μm.

On the other hand, Comparative Example e1 is a linear motion guide device in which the guide rail is formed of silicon nitride having a specific strength of 1.5 × 10 ⁷ mm. The rolling element (surface hardness: Hv700, surface roughness: Comparative Example e1) A boride film is not formed on the surface of 0.05 μm Ra). Comparative example e2 is a linear motion guide device in which the guide rail is formed of silicon nitride having a specific strength of 2.7 × 10 ⁷ mm. The rolling element of this comparative example e2 (surface hardness: Hv710, surface roughness: No boride film is formed on the surface of 0.05 μm Ra). Further, Comparative Example e3 is a linear motion guide device in which the guide rail is made of silicon nitride having a specific strength of 2.2 × 10 ⁷ mm. The surface roughness of the rolling element of Comparative Example e3 is 0. A boride film (surface hardness: Hv1650) of 08 μmRa is formed. The planar portion roughness Ra of the guide rail 13 used in Comparative Examples e1 to e3 is 0.6 μm.

When forming a boride film on the surface of the rolling element, for example, boron is diffused and infiltrated on the surface of the rolling element, followed by quenching and tempering to form a uniform boride film on the surface of the rolling element. As a method of diffusing and infiltrating boron on the surface of the rolling element, a gas method in which boron is diffused and infiltrated using a mixed gas composed of diborane or boron trichloride and hydrogen as a treating agent, boron or ferroboron and alumina and There are a powder method in which boron is diffused and permeated using a mixed powder of ammonium chloride, and an immersion method in which boron is diffused and permeated using borax, sodium oxide, and potassium oxide as treatment agents. Among these methods, the gas method has a problem that the processing gas is toxic and the powder method has a high processing cost. In general, the boride film is composed of two layers, an Fe ₂ B layer and an FeB layer, and the hardness of the surface Fe ₂ B layer reaches Hv 1700 to Hv 2000 and is very brittle. Is preferably an Fe ₂ B layer. Therefore, when a boride film is formed on the surface of the rolling element, by using the above-described immersion method, by performing diffusion permeation treatment under the conditions of treatment temperature: 900 ° C. to 1000 ° C., treatment time: 3 hours to 6 hours, A boride film (hardness: Hv1000 to Hv1700) having a Fe ₂ B layer on the surface can be obtained.

  In addition, since it is gradually cooled after the boride treatment, the base of the boride film is generally a ferrite or pearlite or a mixed structure of ferrite and pearlite, and the strength required for the rolling element is insufficient, so that it can withstand a large contact stress. It may not be possible. For this reason, even if it can be used as a sliding part in a state where it is just borated, it cannot be applied to a rolling element such as a rolling bearing. Therefore, by using a material that is hardened by quenching as the base material of the rolling element and performing quenching and tempering after the boride treatment, it is possible to ensure a strength sufficient to withstand the stress caused by the contact with the guide rail.

  In order to give sufficient quenching hardness to the base material of the rolling element, sufficient quenching hardness can be imparted by using steel with a high carbon content, but the atomic radius is larger than carbon atoms during the boride treatment. Boron atoms enter from the surface of the base material. For this reason, when the carbon content of the base material is 1.0% or more, boriding properties are inhibited, and it becomes difficult to form a boride film, and the boride film may disappear after polishing of the rolling elements. . On the other hand, when the carbon content of the base material is 0.3% or less, sufficient core strength to support the base of the boride film cannot be obtained. Therefore, in order to satisfy all of the film thickness, hardness, and core strength of the boride film, the total carbon content is 0.3 wt% to 1.0 wt%, preferably 0. It is preferable to use 4 wt% to 0.9 wt% of steel.

  For Examples E1 to E3 and Comparative Examples e1 to e3, one cycle was 0.2 seconds, preload was 55 N, and continuous operation was performed for 8 hours with a bending moment applied to the two rails via a spring. It was. After the test, the amount of decrease in the frictional resistance of each rail was measured, and the amount of wear of the rolling elements was evaluated. The evaluation results are shown in Table 12. The amount of decrease in frictional resistance shown in Table 12 is shown as a relative value with the amount of decrease in frictional resistance of Comparative Example e1 as 1.

As shown in Table 12, each of the linear motion guide devices of Examples E1 to E3 shows an extremely low value of the wear amount of the rolling element of about 1/200 to 1/125 compared to that of Comparative Example e1. ing. This is because in Comparative Example e1, the guide rail is formed of silicon nitride having a low specific strength and the planar portion roughness Ra is large, while in Examples E1 to E3, the guide rail has a high ratio of 2 × 10 ⁷ mm or more. This is because it is made of high-strength silicon nitride, has a small flat surface roughness Ra, and has improved wear resistance due to the boride film.

In addition, each of the linear motion guide devices of Examples E1 to E3 shows a lower value of the amount of wear of the rolling elements than that of Comparative Example e2. This is because the comparative example e2 has no boride film formed on the surface of the rolling element, while the examples E1 to E3 have the boride film formed on the surface of the rolling element.
Further, each of the linear motion guide devices of Examples E1 to E3 shows a lower value of the amount of wear of the rolling elements than that of Comparative Example e3. This is because in Comparative Example e3, the surface hardness and surface roughness of the boride film formed on the surface of the rolling element are Hv1650 and 0.08 μmRa, while Examples E1 to E3 are formed on the surface of the rolling element. This is because the surface hardness of the boride film is in the range of Hv1000 to Hv1700, and the surface roughness of the nitride film is 0.05 μmRa or less.

FIG. 13 shows the result of examining the correlation between the surface hardness of the boride film formed on the surface of the rolling element and the durability of the linear motion guide device. Note that the guide rail of the linear motion guide device used here is formed of silicon nitride (specific strength: 2.6 × 10 ⁷ mm) obtained by pressure sintering at about 100 atm. Further, the durability on the vertical axis in the figure is shown as a relative value with the preload loss amount of Comparative Example e1 as 1.

  As shown in FIG. 13, when the surface hardness of the boride film formed on the surface of the rolling element is out of the range of Hv1000 to Hv1700, the durability of the linear motion guide device is drastically lowered. This is because when the surface hardness of the boride film formed on the surface of the rolling element is less than Hv1000, the wear difference of the rolling element is promoted by increasing the hardness difference from the rail material, and the surface hardness of the boride film is also increased. This is because if the thickness exceeds Hv1700, the boride film becomes very brittle. Therefore, the surface hardness of the boride film formed on the surface of the rolling element is preferably in the range of Hv1000 to Hv1700.

Next, FIG. 14 shows the result of examining the correlation between the surface roughness of the boride film formed on the surface of the rolling element and the durability of the linear motion guide device. Note that the guide rail of the linear motion guide device used here is formed of silicon nitride (specific strength: 2.6 × 10 ⁷ mm) obtained by pressure sintering at about 100 atm. Further, the durability on the vertical axis in the figure is shown as a relative value with the preload loss amount of Comparative Example e1 as 1.

As shown in FIG. 14, when the surface roughness of the boride film formed on the surface of the rolling element exceeds 0.05 μmRa, the durability of the linear motion guide device sharply decreases. This is because when the surface roughness of the boride film exceeds 0.05 μmRa, the minute irregularities on the surface of the rolling element are likely to be in direct contact with the surface of the rolling element rolling groove, and the surface of the rolling element rolling groove is formed by the boride film. This is because the surface of the rolling element is damaged or the wear on the surface of the rolling element rolling groove is promoted. Accordingly, the surface roughness of the boride film formed on the surface of the rolling element is preferably 0.05 μmRa or less.
Next, Examples F1 to F9 and Comparative Examples f1 to f4 of the present invention are shown in Table 13.

In Table 13, Examples F1 to F9 are 0.04 to 0.2 μm in the width direction surface roughness of the rolling element rolling groove 16 of the guide rail 13, 0.02 to 0.1 μm in the longitudinal direction surface roughness, and are distorted. This is a linear motion guide device having a degree (Sk value) of -0.1 to +1.
On the other hand, in Comparative Examples f1 to f4, the width-direction surface roughness of the rolling element rolling groove 16 of the guide rail 13 is 0.2 to 0.25 μm, the longitudinal surface roughness is 0.15 μm, and the degree of distortion (Sk This is a linear motion guide device in which (value) is -1.4 to +1.
In Examples F1 to F9 and Comparative Examples f1 to f4, silicon nitride (specific strength: 3.1 × 10 ⁷ mm) obtained by pressure sintering was used as a rail material, and grease was NF2. The rolling elements in each example are formed from martensitic stainless steel.

FIG. 15 shows a testing machine simulating a component mounting apparatus, and durability tests of Examples F1 to F9 and Comparative Examples f1 to f4 were performed using this testing machine. Here, the test machine has two guide rails 13 serving as specimens arranged in parallel on the test machine, and one end of each guide rail 13 is connected by a spring 20, and the guide rail 16 moves at high speed. In this case, the load generated in the case can be applied to the specimen. These rails 13 are reciprocated at a high speed by an external drive source (not shown), and a test under conditions close to those of an actual machine becomes possible. Further, the initial setting preloads applied to the sliders 15A and 15B assembled to the specimen are 1.5N and 0.8N, respectively.
The test was performed up to 10 × 10 ⁶ cycles with a spring load of 100 N, a stroke of 90 mm, and a reciprocation cycle of 0.15 seconds, and the preload reduction amount was measured by removing the specimen.

The result of having tested about durability of Examples F1-F9 and Comparative Examples f1-f4 is shown in FIG.16, FIG17 and FIG.18.
In FIG. 16, the horizontal axis indicates the surface roughness in the width direction of the rolling element rolling groove formed on the guide rail, and the vertical axis indicates the amount of preload reduction after the durability test. As is apparent from FIG. 16, it can be seen that the amount of preload loss is extremely reduced by setting the surface roughness in the width direction of the rolling element rolling groove to 0.02 μmRa or less.

In FIG. 17, the horizontal axis indicates the surface roughness in the longitudinal direction of the rolling element rolling grooves formed on the guide rail, and the vertical axis indicates the amount of preload reduction after the durability test. As is clear from FIG. 17, it is understood that the preload loss can be effectively suppressed by setting the surface roughness of the rolling element rolling groove in the longitudinal direction to 0.1 μmRa or less.
FIG. 18 shows the relationship between the degree of distortion of the surface roughness of the rolling element rolling groove and the durability of Examples F1 to F9 and Comparative Examples f3 and f4. As is apparent from the figure, it is understood that the preload loss can be more effectively suppressed by making the degree of distortion (Sk value) of the surface roughness of the rolling element rolling groove negative.

From the above, the wear of the ceramic guide rail and the rolling element is suppressed by setting the rolling surface rolling groove width-direction surface roughness to 0.02 μmRa or less and the longitudinal surface roughness to 0.1 μmRa or less. can do. Moreover, by making the degree of distortion (Sk value) of the surface roughness of the rolling element rolling groove negative, it is possible to more effectively suppress wear of the ceramic guide rail and the rolling element.
Table 14 shows the silicon nitride materials used in Examples G1 to G4 of the present invention and Comparative Examples g1 to g4.

These silicon nitride materials contain a total of 10 wt% of Al ₂ O ₃ and Y ₂ O ₃ and are sintered at a sintering temperature of 2000 ° C. At this time, the cooling rate after sintering was changed at 25 to 150 ° C./hr to change the crystallization rate of the auxiliary component and change the thermal conductivity of the material.
Using these silicon nitrides as the rail material of the guide rail 13, examples and comparative examples as shown in Table 15 were prepared.

In Table 15, Examples G1-G4 comprised the guide rail 13 with the silicon nitride 3-6 of Table 14, respectively. In any case, the planar portion roughness, strength, and thermal conductivity are within the recommended range of the present invention. On the other hand, Comparative Example g1 and Comparative Example g2 use silicon nitrides 1 and 2 that are outside the recommended range of the present invention as the rail material, with thermal conductivities of 20 W / m · K and 40 W / m · K, respectively. It is. Comparative Example g3 is an example in which silicon nitride 7 having a low specific strength of 1.8 × 10 ⁷ mm is used as a rail material, although the thermal conductivity satisfies 50 W / m · K and the recommended range of the present invention. is there. Comparative Example g4 is an example in which silicon nitride 8 having a fracture toughness value of less than 5 MPa · m ^0.5 is used as a rail material, although the thermal conductivity and bending strength satisfy the recommended ranges. Moreover, the planar part roughness of a guide rail is 0.3 micrometer in the case of Examples G1-G4, and is 0.6 micrometerRa in the case of Comparative Examples g1-g4.

The working characteristics of these Examples G1 to G4 and Comparative Examples g1 to g4 were evaluated using the linear motion test apparatus shown in FIG. In addition, the linear motion guide devices of the respective examples and comparative examples are provided with a vibration pickup, and a change in vibration value generated during operation can be measured by a vibration meter (not shown).
A guide rail having a length of 330 mm, a width of 14 mm, and a thickness of 8 mm was used. The load applied by the tension spring was 120 N, the operation cycle was 8 Hz, and the operation stroke was 90 mm. The grease used was a synthetic hydrocarbon base oil with a urea compound added as a thickener.

The life test of the linear motion guide device was performed at the rate of increase in vibration (= final vibration value / initial vibration value) when the cumulative number of reciprocations after the start of the test reached 1 × 10 ⁷ times. After the life test, a guide rail bending strength test is conducted, and the guide rail is loaded with a stress obtained by multiplying the bending stress applied on the actual machine by a safety factor on the weakest part (notch) of the guide rail. The strength of the rail was evaluated. For each of the examples and comparative examples shown in Table 15, repeated bending stress was similarly applied, and the number of repetitions until breakage was measured.

The results of the life test and the strength evaluation test described above are collectively shown in FIG.
FIG. 19 shows the results of arranging the test results of the examples and comparative examples shown in Table 15 according to the thermal conductivity of the guide rail material. In the same figure, the vibration increase rate on the vertical axis is shown as a relative value with the value of Comparative Example g1 set to 1 in order to display the test result in an easy-to-understand manner, and each evaluation result mark is a bending strength test. In FIG. 2, the case where no crack was generated is indicated by “◯”, and the case where the crack was observed was indicated by “X”. As can be seen from FIG. 19, by forming the guide rail with high thermal conductivity silicon nitride having a thermal conductivity of 46 W / m · K or more, the rise in rolling contact surface temperature is effectively suppressed, and the grease viscosity is reduced. It is possible to maintain a stable operating state for a long time by limiting the deterioration of the lubrication condition due to the decrease. However, in Comparative Example g4, since the fracture toughness value was 5 MPa · m ^0.5 or less, occurrence of cracks was observed. Further, in the case of Comparative Example g3 in which the specific strength of silicon nitride is 2.0 × 10 ⁷ mm or less, although the temperature rise is suppressed, the notch is broken at a specified load, and guidance is given due to strength constraints. Cannot be used as rail material.

In FIG. 20, the result of having arranged the result of the repeated bending evaluation test by the fracture toughness value of the rail material is shown. Even if the specific strength of the rail material is 2.0 × 10 ⁷ mm or more, the comparative example g4 in which the flat surface roughness is larger than 0.5 μm and the fracture toughness value is less than 5 MPa · m ^0.5 is the specified load. The test was broken during the test due to repeated bending stress. On the other hand, other examples having a plane roughness of 0.3 μm, a specific strength of 2.0 × 10 ⁷ mm or more, and a fracture toughness value of 5 MPa · m ^0.5 or more are ruptures of Comparative Example g4 Even when a cycle 1000 times the cycle is loaded, it does not break.

  The present invention is not limited to the embodiment described above. For example, in the above-described embodiment, the case where the present invention is applied to the head lifting mechanism of the electronic component mounting apparatus has been described. However, the present invention is not limited to the above-described embodiment, and for example, the bonding head lifting / lowering of the wire bonding apparatus. Of course, the present invention can be applied to the mechanism.

[Embodiment 2]
FIG. 21 is a partial longitudinal sectional view showing the structure of a deep groove ball bearing which is an embodiment of the rolling device according to the present invention.
This ball bearing includes an outer ring 1, an inner ring 2, a plurality of balls 3 that are rotatably arranged between the outer ring 1 and the inner ring 2, and a resin crown-shaped cage that holds the plurality of balls 3. (Not shown). In addition, the outer ring | wheel 1 is corresponded to the support body which is a structural requirement of this invention, and the inner ring | wheel 2 is corresponded to the needle | mover which is a structural requirement of this invention.

The outer ring 1, inner ring 2, and ball 3 are all made of ceramic material, cermet, or cemented carbide, and the specific strength of the ceramic material, cermet, or cemented carbide is 1.2 × 10 ⁷ mm or more. It is. Furthermore, the thermal shock value of the ceramic material, cermet, or cemented carbide is 1.5 times or more the operating environment temperature of the ball bearing, and the ceramic material, the cermet, or the cemented carbide at the operating environment temperature. The bending strength of the alloy is 500 MPa or more.

  When such a ball bearing of this embodiment is made of a ceramic material, it is lightweight and has high rigidity, and is excellent in corrosion resistance, wear resistance, and heat resistance. Further, the centrifugal force acting on the ball 3 at the time of rotation is reduced, the device can be operated at a higher speed, and the heat generation is further reduced. Furthermore, since the specific gravity is small, even when the rotational speed is high, the energy for driving the ball bearing, that is, the amount of power used is small. Therefore, energy consumption can be reduced and energy saving can be achieved. Further, even under high-speed rotation, there is no risk of seizure due to adhesion at the contact point unlike metal materials. Further, cermet and cemented carbide have a characteristic that they have a relatively high bending strength and are easy to process and inexpensive compared to ceramic materials.

Furthermore, since the specific strength of the ceramic material, cermet, or cemented carbide is 1.2 × 10 ⁷ mm or more, cracks hardly propagate on the surface or inside of the ceramic material, cermet, or cemented carbide, and peeling or Since wear does not easily occur, this ball bearing has a long life even if it operates at high speed.
Furthermore, the thermal shock value of the ceramic material, cermet, or cemented carbide is 1.5 times or more the operating environment temperature of the ball bearing, and the bending strength of the ceramic material, cermet, or cemented carbide at the operating environment temperature. Therefore, the outer ring 1 or the outer ring 1 can be used even in the case where a temperature gradient is generated inside the ball bearing by being heated and heated in a high temperature environment or in a high temperature / corrosive environment, and a thermal stress is generated by the temperature gradient. Small cracks are unlikely to propagate to the surface of the inner ring 2 and wear and cracks are less likely to occur. Therefore, this ball bearing has a long life even in a high temperature environment or a high temperature / corrosion environment.

Next, in the ball bearing having the same configuration as the above, various changes were made to the outer ring, the inner ring, and the ceramic material, cermet, or cemented carbide constituting the ball, and various evaluations were performed by a rotation test. .
As ball bearings of Examples H1 to H24 and Comparative Examples h1 to h3, ball bearings manufactured by NSK Ltd. (nominal number 6206, inner diameter 30 mm, outer diameter 62 mm, width 16 mm) were used.

The outer ring and inner ring are made of ceramic material, cermet, or cemented carbide as shown in Table 16 and Table 17, and the balls are made of silicon nitride (Nippon Specialty Ceramics) for Examples H1 to H12, H18 to H24 and Comparative Example h3. EC-141 manufactured by the company, specific strength 2.94 × 10 ⁷ mm, thermal shock value: 880 ° C., bending strength: 1000 MPa), and Examples H13 to H17 and Comparative Examples h1 and h2 are the same type of ceramic as the inner ring. Composed of materials. In addition, a fluorinated resin crown-shaped cage was used as the cage. Tables 16 and 17 also show the specific strength ([bending strength] / [density]) and bending strength of the ceramic material, cermet, and cemented carbide.

The ceramic material, cermet, and cemented carbide used are as follows.
Silicon nitride 1h: NBD200 manufactured by Saint-Gobain Norton, specific strength 2.9 × 10 ⁷ mm, bending strength 980 MPa
-Silicon nitride 2h: NPN-3 manufactured by Nippon Tungsten Co., Ltd., specific strength 3.9 × 10 ⁷ mm, bending strength 1300 MPa
Silicon nitride 3h: Kyocera SN733, specific strength 3.1 × 10 ⁷ mm, bending strength 980 MPa
・ Silicon nitride type 4h: Nippon Steel Corporation S110H, specific strength 3.6 × 10 ⁷ mm, bending strength 1180 MPa

Zirconia system 1h: Z703 manufactured by Kyocera Corporation, specific strength 3.6 × 10 ⁷ mm, bending strength 1960 MPa
・ Zirconia 2h: NPZ-1 manufactured by Nippon Tungsten Co., Ltd., specific strength 2.9 × 10 ⁷ mm, bending strength 1800 MPa
-Zirconia 3h: NPZ-3 manufactured by Nippon Tungsten Co., Ltd., specific strength 1.7 × 10 ⁷ mm, bending strength 1700 MPa
Zirconia 4h: Z21H0 manufactured by Kyocera Corporation, specific strength 1.4 × 10 ⁷ mm, bending strength 784 MPa

-Silicon carbide type 1h: NPS-1 manufactured by Nippon Tungsten Co., Ltd., specific strength 1.8 × 10 ⁷ mm, bending strength 560 MPa
Alumina-based 1h: AZ-93 manufactured by Saint-Gobain Norton, specific strength 2.5 × 10 ⁷ mm, bending strength 1180 MPa
Alumina-based 2h: NPA-2 manufactured by Nippon Tungsten Co., Ltd., specific strength 1.9 × 10 ⁷ mm, bending strength 835 MPa
Alumina 3h: A-601D manufactured by Kyocera Corporation, specific strength 1.0 × 10 ⁷ mm, bending strength 400 MPa
Alumina 4h: AL-16 manufactured by Toshiba, specific strength 0.8 × 10 ⁷ mm, bending strength 320 MPa

Cemented carbide 1h: WC-Co G3 manufactured by Nippon Tungsten Co., Ltd., specific strength 1.77 × 10 ⁷ mm, thermal shock value 800 ° C., bending strength 1800 MPa
Cemented carbide 2h: WC-Ni-Cr-Mo type NR11 manufactured by Nippon Tungsten Co., Ltd., specific strength 1.78 × 10 ⁷ mm, thermal shock value 700 ° C., bending strength 2400 MPa
Cemented carbide 3h: WC-TiC-TaC RCRC, manufactured by Nippon Tungsten Co., Ltd., specific strength 0.68 × 10 ⁷ mm, thermal shock value 550 ° C., bending strength 1000 MPa
Cemented carbide 4h: WC-Ni-Cr-based M61U manufactured by Sumitomo Electric Industries, Ltd., specific strength 1.95 × 10 ⁷ mm, thermal shock value 500 ° C., bending strength 2500 MPa

Cermet 1h: TiC-TaN-Ni-Mo based DUX40 manufactured by Nippon Tungsten Co., Ltd., specific strength 2.73 × 10 ⁷ mm, thermal shock value 550 ° C., bending strength 1800 MPa
-Cermet 2h: TiC-TaN-Ni-Mo-based DUX30 manufactured by Nippon Tungsten Co., Ltd., specific strength 2.46 × 10 ⁷ mm, thermal shock value 550 ° C., bending strength 1600 MPa
・ Cermet 3h: boride system UD-II-35T manufactured by Asahi Glass Co., Ltd., specific strength 2.23 × 10 ⁷ mm, thermal shock value 800 ° C., bending strength 2000 MPa
・ Cermet 4h: boride system UD-II-50T manufactured by Asahi Glass Co., Ltd., specific strength 2.55 × 10 ⁷ mm, thermal shock value 1000 ° C., bending strength 2350 MPa

Next, the evaluated contents and conditions of the rotation test will be described.
First, the high-speed rotation performance will be described. The ball bearing was attached to a bearing rotation tester manufactured by NSK Ltd., and the initial radial load was set to 490 N, and the ball bearing was rotated at a rotational speed of 1000 min ⁻¹ in water at room temperature (inner ring rotation). Then, the rotational speed was increased by 1000 min ⁻¹ every hour, and the high speed performance was evaluated with the rotational speed at the time when the vibration value increased rapidly as the limit rotational speed. The results are summarized in Table 16 and Table 17. In addition, the limit rotational speed of the ball bearing in each Example and the comparative example is shown by the relative value when the limit rotational speed of the comparative example h1 is 1.

Next, durability (life) will be described.
The ball bearing was attached to the same bearing rotation tester manufactured by NSK Ltd., the radial load was set to 490 N, and it was rotated at a rotational speed of 10,000 min ⁻¹ in water at room temperature (inner ring rotation). The point of time when the vibration value increased to three times the initial value was defined as the life of the ball bearing. The results are summarized in Table 16 and Table 17. In addition, durability (life) of the ball bearing in each Example and a comparative example is shown by the relative value when the durability (life) of the comparative example h1 is set to 1.

  Examples H1 to H12 and H18 to H24 are ball bearings in which the outer ring and the inner ring are made of the same kind of ceramic material, cermet, or cemented carbide. In Examples H13 to H17, the outer ring and the inner ring are made of different ceramic materials (that is, the specific strengths are different), and the specific strength of the ceramic material constituting the inner ring that is the mover is set to the outer ring that is the support. This is a ball bearing that is larger than the specific strength of the ceramic material to be formed.

From Table 16 and Table 17, the ball bearings of Examples H1 to H24 are composed of an inner ring, an outer ring, and a ball made of a ceramic material, cermet, or cemented carbide having a specific strength of 1.2 × 10 ⁷ mm or more. In comparison with the ball bearings of comparative examples h1 to h3 in which the inner ring, the outer ring, and the ball are made of ceramic material, cermet, or cemented carbide having a specific strength of less than 1.2 × 10 ⁷ mm, It can be seen that the durability is excellent (high speed rotation performance and long life). Moreover, it turns out that there exists a tendency that the limit rotational speed and durability of a ball bearing are excellent, so that specific strength is large.

  FIG. 22 is a graph showing a part of the results of Table 16 and the evaluation results of other ball bearings (ball bearings in which the outer ring and the inner ring are made of the same kind of ceramic material). In FIG. 22, the horizontal axis represents the specific strength of the ceramic material, the left vertical axis represents the limit rotational speed, and the right vertical axis represents the durability. Further, in FIG. 22, data relating to the limit rotational speed is indicated by a circle, and data relating to durability is indicated by a square.

As can be seen from the graph of FIG. 22, when the specific strength is 1.2 × 10 ⁷ mm or more, excellent limit rotational speed and durability are imparted to the ball bearing. Moreover, if it is 1.5 × 10 ⁷ mm or more, the excellent limit rotational speed and durability of the ball bearing will be more reliable, and if it is 1.8 × 10 ⁷ mm or more, the limit rotational speed and durability of the ball bearing will be increased. The property is further improved.

  Next, the results of evaluating the high temperature durability of a ball bearing having a configuration similar to the above will be described. The ball bearings used in the tests (Examples H25 to H40 and Comparative Examples h4 to h7) are ball bearings (nominal number 6206, inner diameter 30 mm, outer diameter 62 mm, width 16 mm) manufactured by Nippon Seiko Co., Ltd. Further, the ceramic material, cermet, or cemented carbide constituting the ball is variously changed as shown in Table 18 and Table 19.

  The ball was made of silicon nitride (EC-141 manufactured by Nippon Special Ceramics Co., Ltd.), and a SUS304 corrugated cage was used as the cage. Tables 18 and 19 also show the ratio of the thermal shock resistance value of the ceramic material, cermet, or cemented carbide to the ambient temperature (200 ° C.) of the ball bearing ([ceramic material, cermet, or cemented carbide] Thermal shock value] / [Usage environment temperature of ball bearing]), specific strength, and bending strength (MPa) at the use environment temperature (200 ° C.) are shown together.

The ceramic material used is as follows.
-Silicon nitride 2h: NPN-3 manufactured by Nippon Tungsten Co., Ltd., thermal shock value 800 ° C. (4.0), bending strength 1300 MPa, specific strength 3.93 × 10 ⁷ mm
・ Silicon nitride-based 5h: SAN-P manufactured by Shinagawa White Brick Co., Ltd., thermal shock value 650 ° C. (3.25), bending strength 1080 MPa, specific strength 3.34 × 10 ⁷ mm
・ Zirconia 6h: UTZ33H manufactured by NGK, thermal shock value 300 ° C. (1.5), bending strength 1800 MPa, specific strength 2.13 × 10 ⁷ mm
Zirconia 7h: NPZ-5 manufactured by Nippon Tungsten Co., Ltd., thermal shock value 350 ° C. (1.75), bending strength 1800 MPa, specific strength 3.33 × 10 ⁷ mm

Alumina 4h: Toshiba AL-16, thermal shock value 230 ° C. (1.15), bending strength 320 MPa, specific strength 0.84 × 10 ⁷ mm
Alumina 5h: HC2 manufactured by Nippon Special Ceramics Co., Ltd., thermal shock value 300 ° C. (1.5), bending strength 800 MPa, specific strength 1.86 × 10 ⁷ mm
Alumina 6h: Nippon Special Ceramics Co., Ltd. KP990, thermal shock value 160 ° C. (0.8), bending strength 500 MPa, specific strength 1.28 × 10 ⁷ mm
Silicon carbide 1h: NPS-1 manufactured by Nippon Tungsten Co., Ltd., thermal shock value 600 ° C. (3.0), bending strength 560 MPa, specific strength 1.81 × 10 ⁷ mm
Silicon carbide-based 2h: TSC-1 manufactured by Toshiba, thermal shock value 350 ° C. (1.75), bending strength 500 MPa, specific strength 1.81 × 10 ⁷ mm

The numerical value in parentheses after the above thermal shock value is the ratio of the thermal shock value for each ceramic material to the ambient temperature (200 ° C.) of the ball bearing ([thermal shock value of ceramic material] / [ball Value of the ambient temperature of the bearing]. The bending strength and specific strength are bending strength and specific strength at 200 ° C., which is the use environment temperature of the ball bearing.
Moreover, the cermet and the cemented carbide used the above-mentioned thing.

Next, a test method and test conditions for high temperature durability will be described.
The ball bearing was attached to a bearing rotation tester manufactured by NSK Ltd., and the radial load was set to 980 N, and the ball bearing was rotated at high temperature in the air at a rotation speed of 1000 min ⁻¹ without lubrication (inner ring rotation). The ball bearing was heated by a heater wound around a housing containing the outer ring, and the test was started when the outer diameter surface of the outer ring reached a predetermined temperature. And the time when the vibration value at the time of rotation increased rapidly was judged as the life, and the high temperature durability was evaluated. The results are summarized in Table 18 and Table 19. In addition, the high temperature durability (life) of the ball bearing in each Example and Comparative Example is shown as a relative value when the high temperature durability (life) of Comparative Example h4 at each temperature is 1.

  As can be seen from Table 18 and Table 19, in both cases where the heating temperature is 200 ° C. and 300 ° C., the ball bearings of Examples H25 to H40 are higher in durability than the ball bearings of Comparative Examples h4 to h7. The property (lifetime) was excellent. In addition, although the numerical value of the high temperature durability at 200 ° C. may be smaller than the numerical value of the high temperature durability at 300 ° C. as in Example H25, the high temperature durability at 200 ° C. is higher than the high temperature durability at 300 ° C. Is not inferior, and is a relative value with respect to Comparative Example h4.

FIG. 23 is a table summarizing the results in Table 18 when the heating temperature is 200 ° C., and [ceramic material thermal shock resistance] / [ball bearing operating temperature (200 ° C.) for each ceramic material. )] And the bending strength at 200 ° C., which is the use environment temperature of the ball bearing, and the high temperature durability (life) of the ball bearing.
Among the plots in FIG. 23, Δ marks indicate the case where the aforementioned high temperature durability (lifetime) is less than 5. In addition, ◯ indicates a case of 5 or more and less than 10, ● ● indicates a case of 10 or more and less than 20, and ◎ indicates a case of 20 or more.
Also from FIG. 23, it can be seen that the ball bearings of Examples H25 to H32 are superior in high-temperature durability (life) compared to the ball bearings of Comparative Examples h4 and h5.

Next, a deep groove ball bearing which is another embodiment of the rolling device according to the present invention will be described. In this ball bearing, the outer ring, the inner ring, and the ball are all made of a ceramic material, cermet, or cemented carbide, and are preferably used in a high-temperature environment in contact with molten metal. The thermal shock value of the ceramic material, cermet, or cemented carbide is 1.5 times or more the temperature of the molten metal, the bending strength at the temperature of the molten metal is 800 MPa or more, and the specific strength is 1.2. × 10 ⁷ mm or more. In addition, since it is the same as that of the above-mentioned ball bearing (the thing of FIG. 21) about another structure, the description is abbreviate | omitted.

  The ball bearing of this embodiment is heated when immersed in the molten metal because the thermal shock value of the ceramic material, cermet, or cemented carbide is 1.5 times the temperature of the molten metal, Even if thermal stress is generated due to cooling when the molten metal is taken out from the molten metal, minute cracks are unlikely to propagate to the surfaces of the outer ring and inner ring that are constituent members of the ball bearing. Therefore, it is difficult for a large amount of wear powder to be generated, or for cracks to penetrate through the outer ring and the inner ring.

Moreover, since the bending strength of the ceramic material, cermet, or cemented carbide at the temperature of the molten metal is 800 MPa or more, a relatively high contact of 1 to 2.5 GPa between the outer ring, the inner ring and the ball when using the ball bearing. Even if stress is repeatedly applied, minute cracks are unlikely to be generated on the surface, and a reduction in life is suppressed.
Therefore, the ball bearing of this embodiment has a long life even when used in a high-temperature environment in contact with the molten metal. Therefore, it can be suitably used for a molten metal plating apparatus or the like.

  Next, the results of evaluating the high temperature durability of a ball bearing having a configuration similar to the above will be described. The ball bearings used in the tests (Examples H41 to H51 and Comparative Examples h8 to h15) are ball bearings (nominal number 6206, inner diameter 30 mm, outer diameter 62 mm, width 16 mm) manufactured by Nippon Seiko Co., Ltd. Further, as shown in Table 20 and Table 21, various changes were made to the ceramic material, cermet, or cemented carbide constituting the ball.

The balls were made of silicon nitride (EC-141 manufactured by Nippon Special Ceramics Co., Ltd.), and a Ta machined cage was used as the cage. Tables 20 and 21 also show the ratio of the thermal shock value of ceramic material, cermet, or cemented carbide to the molten metal temperature (460 ° C.) (the thermal shock value of ceramic material, cermet, or cemented carbide). ] / [Molten metal temperature]), specific strength (× 10 ⁷ mm) and bending strength (MPa) at the molten metal temperature (460 ° C.).

The ceramic material used is as follows.
Silicon nitride 2h: NPN-3 manufactured by Nippon Tungsten Co., Ltd., thermal shock value 800 ° C. (1.7), bending strength 1300 MPa, specific strength 3.93 × 10 ⁷ mm
Silicon nitride 6h: S-110 manufactured by Nippon Steel Sialon Co., Ltd., thermal shock value 750 ° C. (1.6), bending strength 870 MPa, specific strength 3.6 × 10 ⁷ mm
・ Silicon nitride-based 7h: MSN manufactured by Mitsui Mining & Materials, thermal shock value 700 ° C. (1.5), bending strength 870 MPa, specific strength 2.75 × 10 ⁷ mm
-Silicon nitride 8h: EC141 manufactured by Nippon Special Ceramics Co., Ltd., thermal shock value 880 ° C. (1.9), bending strength 990 MPa, specific strength 2.94 × 10 ⁷ mm
・ Silicon nitride type 9h: SN-55 manufactured by NGK, thermal shock value 800 ° C. (1.7), bending strength 800 MPa, specific strength 2.66 × 10 ⁷ mm

・ Silicon nitride type 10h: SN-73 manufactured by NGK, thermal shock value 1000 ° C. (2.2), bending strength 1140 MPa, specific strength 3.59 × 10 ⁷ mm
-Silicon nitride 11h: SN-84 manufactured by NGK, thermal shock value 1000 ° C. (2.2), bending strength 850 MPa, specific strength 2.69 × 10 ⁷ mm
Silicon nitride 12h: TSN-05 manufactured by Toshiba, thermal shock value 600 ° C. (1.3), bending strength 690 MPa, specific strength 2.19 × 10 ⁷ mm
-Silicon nitride type 13h: SRBSN manufactured by Kimura Fire Resistance Co., Ltd., thermal shock value 800 ° C. (1.7), bending strength 790 MPa, specific strength 2.42 × 10 ⁷ mm
Silicon nitride-based 14h: SSN manufactured by Kimura Fire Resistance Co., Ltd., thermal shock value 700 ° C. (1.5), bending strength 790 MPa, specific strength 2.56 × 10 ⁷ mm

Zirconia 7h: NPZ-5 manufactured by Nippon Tungsten Co., Ltd., thermal shock value 350 ° C. (0.8), bending strength 1790 MPa, specific strength 3.33 × 10 ⁷ mm
・ Zirconia 8h: UTZ33H manufactured by Nippon Special Ceramics Co., Ltd., thermal shock value 300 ° C. (0.7), bending strength 1290 MPa, specific strength 2.13 × 10 ⁷ mm
Alumina 5h: HC2 manufactured by Nippon Special Ceramics Co., Ltd., thermal shock value 300 ° C. (0.7), bending strength 790 MPa, specific strength 1.86 × 10 ⁷ mm

The numerical value in parentheses after the above thermal shock value is the ratio of the thermal shock value and the molten metal temperature (460 ° C.) for each ceramic material ([thermal shock value of ceramic material] / [molten metal temperature]). Value). The bending strength and specific strength are bending strength and specific strength at 460 ° C. which is a molten metal temperature.
Moreover, the cermet and the cemented carbide used the above-mentioned thing.

Next, a test method and test conditions for high temperature durability will be described.
The ball bearing was attached to a bearing rotation tester manufactured by NSK Ltd. at room temperature, and the ball bearing was immersed in a 460 ° C. molten zinc bath. And in the state immersed in the molten zinc bath, it was rotated on the conditions of an axial load of 980 N and a rotational speed of 200 min ⁻¹ (inner ring rotation). Then, the high temperature durability was evaluated using the rotation time of the ball bearing until the rotational torque increased to three times the initial value as the lifetime. The components of the molten zinc bath are 0.1 to 5% for Al, 0.1% or less for Fe, 0.1% or less for Pb, and the balance is Zn.

The results of evaluation are summarized in Table 20 and Table 21. In addition, the high temperature durability (life) of the ball bearing in each Example and Comparative Example is shown as a relative value when the high temperature durability (life) of Comparative Example h8 is 1.
Further, FIG. 24 shows a graph of the results of Table 20. The graph of FIG. 24 shows the bending strength at the molten metal temperature (460 ° C.) as the value of [the thermal shock value of the ceramic material] / [molten metal temperature (460 ° C.)] and the use environment temperature of the ball bearing for each ceramic material. And the relationship between the high temperature durability (life) of the ball bearing.

Among the plots in FIG. 24, the mark ● indicates the case where the life (relative value) is 20 or more, and the mark ◯ indicates the case where the life is 10 or more and less than 20. In addition, the Δ mark indicates a case of 5 or more and less than 10, and the x mark indicates a case of less than 5.
From Table 20, Table 21, and FIG. 24, in the ball bearings of Examples H41 to H51, the value of [Thermal shock value of ceramic material, cermet, or cemented carbide] / [Mold metal temperature] is 1.5 or more. In addition, since the bending strength of the ceramic material, cermet or cemented carbide at the molten metal temperature (460 ° C.) is 800 MPa or more and the specific strength is 1.2 × 10 ⁷ mm or more, it is immersed in the molten metal bath. When used in this state, it can be seen that the high temperature durability (life) is superior to the ball bearings of Comparative Examples h8 to h15.

  Further, a boride-based cermet which is a hard alloy having excellent hardness and strength up to a high temperature can be obtained by, for example, the following method. (MoB, WB) and Ni powder which are raw materials constituting the hard phase, and Ni, (W, Ni) -Ti alloy, Ni-Ti alloy, (Cr, Ni) -Ta which are the raw materials constituting the binder phase An alloy, a Ni—Nb alloy, and a powder selected from carbon were weighed and mixed and pulverized in a wet manner using an organic solvent such as ethanol as a medium by a rotating ball mill, a vibration ball mill, or the like. After drying the obtained slurry under reduced pressure, it was pressure-molded using a die press, an isostatic press, or the like, and was usually sintered at 1100 to 1400 ° C. in a non-oxidizing atmosphere such as in a vacuum. Examples of such MoB-Ni hard alloys include trade names UD-II-30, UD-IIT-35T, and UD-II-50T manufactured by Asahi Glass Co., Ltd.

In order to evaluate the sliding characteristics of the boride cermet as described above, the amount of wear was investigated using a four-ball wear tester.
First, the method of the four-ball wear test will be described. Three spheres were arranged in an equilateral triangle shape so as to contact each other and fixed in the sample container, and one test sphere was placed in a recess formed at the center of these three fixed spheres. And while giving a rotation to a test ball | bowl, the load was loaded from the downward direction. The wear test was performed in a lubricating oil (Nippon Mitsubishi Mitsubishi Corporation Super Malpas, viscosity 2). The test conditions are: rotational speed: 7000 min ⁻¹ , load: 147 N, temperature: room temperature, test time: 1 hour. Furthermore, the diameter of the test ball was 3/8 inch, and the test ball and the fixed ball were made of the same material.

  In this wear test, the test was terminated when the torque increased to three times the initial value. And the area of the wear trace of three fixed spheres after a test was measured, and the average value was made into the amount of wear. The test results are shown in Table 22. The amount of wear in each example and comparative example is shown as a relative value when the amount of wear in comparative example h16 is 1.

  As can be seen from Table 22, the amount of wear of the boride cermets of Examples H52 to H57 was much smaller than those of Comparative Examples h16 and h17. The reason for this is considered that boride-based cermet is a composite of a boron compound having lubricity and a metal.

Next, in order to evaluate the durability of the boride cermet as described above, a rolling bearing was manufactured using the boride cermet as a material, and a rotation test was performed.
The rolling bearings used in the rotation test (Examples H58 to H63 and Comparative Examples h18 to h20) are ball bearings (nominal number 6000, inner diameter 10 mm, outer diameter 26 mm, width 8 mm) manufactured by Nippon Seiko Co., Ltd. , And the materials constituting the rolling elements are variously changed as shown in Table 23. The cage is a crown-shaped holder made of a resin composition produced by an injection molding method (containing 80% by volume of tetrafluoroethylene / perfluoroalkyl vinyl ether resin (PFA) and 20% by volume of potassium titanate whiskers). A vessel was used.

The above ball bearing is mounted on a bearing rotation tester manufactured by Nippon Seiko Co., Ltd. (the shaft of the rotation tester is made of stainless steel), and the rotational speed is 1500 min ^{−1, the} radial load is 300 N, and the temperature is 250 ° C. Rotated under no lubrication. The point of time when the vibration value increased to three times the initial value was defined as the life of the ball bearing. The results are summarized in Table 23. The durability (life) of the ball bearings of each example and comparative example is shown as a relative value when the durability (life) of Comparative Example h18 is 1.

  As can be seen from Table 23, the durability of the ball bearings of Examples H58 to H63 was very excellent as compared with Comparative Examples h18 to h20. A graph showing the correlation between the durability of the ball bearing and the bending strength of the material constituting the ball bearing is shown in FIG. From this graph, it can be seen that the durability is remarkably excellent when the bending strength is 850 MPa or more.

Next, in order to evaluate the durability of the boride-based cermet in the molten metal, a rolling bearing was manufactured using the boride-based cermet as a raw material, and a rotation test was performed.
The rolling bearings used in the rotation test (Examples H64 to H66 and Comparative Example h21) are thrust ball bearings (nominal number 51305, inner diameter 25 mm, outer diameter 52 mm, height 18 mm) manufactured by Nippon Seiko Co., Ltd. As shown in Table 24, the materials constituting the material are variously changed. In any of the thrust ball bearings, the rolling element is composed of the above-described silicon nitride 8h (the number of rolling elements is three), and is provided with a C / C composite rice bran cage.

Such a thrust ball bearing was attached to a bearing rotation tester manufactured by Nippon Seiko Co., Ltd. at room temperature, and the thrust ball bearing was immersed in a molten zinc bath at 460 ° C. And in the state immersed in the molten zinc bath, it rotated on the conditions of thrust load 980N and rotational speed 200min- ¹ (inner ring rotation). And durability was evaluated by setting the rotation time of the thrust ball bearing until the rotational torque increased to three times the initial value as the lifetime. The components of the molten zinc bath are the same as those described above.

The results of evaluation are also shown in Table 24. The durability (life) of the ball bearings of each example and comparative example is shown as a relative value when the durability (life) of Comparative Example h21 is 1. Table 24 also shows the fracture toughness K _IC , thermal expansion coefficient, thermal shock resistance, and bending strength and specific strength at the molten metal temperature (460 ° C.) of the boride cermet.
As can be seen from Table 24, the durability of the thrust ball bearings of Examples H64 to H66 was very excellent as compared with Comparative Example h21.

  The present invention is not limited to the above embodiments. For example, in the above embodiment, a deep groove ball bearing or the like has been described as an example. However, the rolling device of the present invention can be applied to various rolling bearings. For example, radial ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, self-aligning roller bearings and other radial type rolling bearings, and thrust type ball bearings and thrust roller bearings such as thrust roller bearings.

Moreover, in the said embodiment, although the rolling bearing was illustrated and demonstrated as a rolling device, the rolling device of this invention is applicable with respect to various other types of rolling devices. For example, the present invention can be suitably applied to other rolling devices such as a linear motion guide device, a ball screw, and a linear motion bearing.
As described above, the rolling device of the present invention is lightweight, excellent in corrosion resistance, thermal shock resistance, and wear resistance, and has a long life even when used at high speed in a high temperature / corrosion environment or a high temperature environment. is there.

[Embodiment 3]
FIG. 26 shows a rolling bearing which is a rolling device according to the present embodiment, in which the rolling element 3 is interposed between the raceway surface 1a (guide surface) of the inner ring 1 and the raceway surface 2a (guide surface) of the outer ring 2. It is inserted and configured.
The outer ring 2 is attached to a housing 4 to constitute a support body, and the inner ring 1 is fixed to a shaft body 5 to constitute a mover.
The inner ring 1 and the outer ring 2 are made of bearing steel such as SUJ2 or SUS440C.
Further, the rolling element 3 is made of a ceramic material or cemented carbide, and by selecting the ceramic material or cemented carbide, the ratio of the linear expansion coefficient of the rolling element 3 to the inner ring 1 and the rolling element 3 to the outer ring 2 are selected. Both the ratios of the linear expansion coefficients are set to 0.45 or less.

  In the rolling bearing having the above-described configuration, the thermal expansion amount of the rolling element 3 is relatively smaller than the thermal expansion amounts of the inner ring 1 and the outer ring 2 even under conditions where the rotation is high speed and the heat generation is large. For this reason, it is possible to effectively reduce the increase in preload due to temperature gradients, and it is difficult to cause seizure even under conditions where heat generation increases under high speed rotation. Can operate for a long time under.

Here, when a ceramic material or a cemented carbide having a ratio of fracture toughness value (MPa · m ^1/2 ) to Vickers hardness (GPa) of 0.40 or more is employed as the rolling element 3, Even if a large centrifugal force is applied to the rolling element 3, cracks are unlikely to occur on the surface or inside of the rolling element 3 made of ceramic material or cemented carbide, and propagation is difficult. For this reason, since peeling and abrasion hardly occur and adhesion is difficult, it can be operated under higher speed rotation conditions and can be operated for a longer lifetime under higher speed rotation conditions.

Here, the fracture toughness value (MPa · m ^1/2 ) of the material employed in the present invention is calculated based on the IF method of JIS R1607 for the flat surface of the material constituting the rolling device. Use the value. As the Vickers hardness, a value measured based on JIS R1610 for a flat surface of a material constituting the rolling device is used.
The inner and outer rings 1 and 2 and the rolling element 3 are all made of a ceramic material or a cemented carbide, and the fracture toughness value (MPa · m ^1/2 ) for the Vickers hardness (GPa) of the ceramic material or the cemented carbide. If the ratio is less than 0.40, if a large centrifugal force is applied to the rolling element 3 under high-speed rotation conditions, cracks are likely to occur or propagate from the surface or internal defects, and wear powder May occur in large quantities or peel off, and the life of the rolling device may be extremely short.

The rolling element 3 has a specific rigidity (ratio of longitudinal elastic modulus (GPa) to density (g / cm ³ )) of 0.90 × 10 ⁸ mm or more and a specific strength of 1.2 × 10 ⁷ mm. The above is preferable.
When the rolling element 3 has a specific rigidity of 0.90 × 10 ⁸ mm or more and a specific strength of 1.2 × 10 ⁷ mm or more, the centrifugal force and gyro moment generated in the rolling element 3 are effectively reduced. In addition, since the rolling element load and slip can be effectively reduced, heat generation is reduced and an increase in preload is reduced, so that seizure hardly occurs. As a result, it can rotate under higher speed conditions and can operate for a long time under high speed rotation.

In addition, when the rolling element 3 has a specific rigidity of 0.90 × 10 ⁸ mm or more, the amount of elastic deformation of the rolling element 3 when receiving a load is reduced, and the rigidity of the rolling device can be improved. it can. For this reason, when using the rolling bearing which is the range of this invention as a rolling bearing which supports the main axis | shaft of a machine tool, the rigidity of a main axis | shaft improves and it can raise the precision of the dimension shape of a workpiece further.

As the ceramic material is not particularly limited, silicon nitride _(Si 3 _{N 4)} type, zirconia (ZrO ₂₎ based, alumina _(Al 2 _{O 3)} based, silicon carbide (SiC) based, aluminum nitride (AlN) system Boron carbide (B ₄ C), Titanium boride (TiB ₂ ), Boron nitride (BN), Titanium carbide (TiC), Titanium nitride (TiN), or a ceramic composite that combines these Examples include materials.

The ceramic material used in the present invention can be blended with a fibrous filler in order to improve fracture toughness, longitudinal elastic modulus, hardness, mechanical strength, and the like. Although it does not specifically limit as a fibrous filler, A silicon carbide whisker, a silicon nitride whisker, an alumina whisker, and an aluminum nitride whisker can be illustrated.
Moreover, although it does not specifically limit as said cemented carbide, The following can be illustrated as a cemented carbide.

That is, WC-Co, WC-Cr ₃ C ₂ -Co, WC-TaC-Co, WC-TiC-Co, WC-NbC-Co, WC-TaC-NbC-Co, WC-TiC -TaC-NbC-Co system, WC-TiC-TaC-Co system, WC-ZrC-Co system, WC-TiC-ZrC-Co system, WC-TaC-VC-Co system, WC-Cr ₃ C ₂ -Co Type, WC—TiC—Cr ₃ C ₂ —Co type, WC—TiC—TaC type, and the like. In addition, non-magnetic and improved corrosion resistance include WC—Ni, WC—Co—Ni, WC—Cr ₃ C ₂ —Mo ₂ C—Ni, WC—Ti (C, N) —TaC. Type, WC—Ti (C, N) type, Cr ₃ C ₂ —Ni type, and the like.

  Here, a typical composition of the WC—Co system is W: Co: C = 70.41 to 91.06: 3.0 to 25.0: 4.59 to 5.94. The typical composition of the WC-TaC-NbC-Co system is W: Co: Ta: Nb: C = 65.7-86.3: 5.8-25.0: 1.4-3.1: 0. .3 to 1.5: 4.7 to 5.8. The typical composition of the WC-TiC-TaC-NbC-Co system is W: Co: Ta: Ti: Nb: C = 65.0-75.3: 6.0-10.7: 5.2-7. .2: 3.2-11.0: 1.6-2.4: 6.2-7.6. A typical composition of the WC—TaC—Co system is W: Co: Ta = 53.51 to 90.30: 3.5 to 25.0: 0.30 to 25.33. A typical composition of the WC—TiC—Co system is W: Co: Ti = 57.27 to 78.86: 4.0 to 13.0: 3.20 to 25.59. A typical composition of the WC—TiC—TaC—Co system is W: Co: Ta: Ti: C = 47.38 to 87.31: 3.0 to 10.0: 0.94 to 9.38: 0. 12-25.59: 5.96-10.15.

For the reasons described above, the rolling device of the present invention is excellent in high-speed rotation performance, such as a rotating part of various pumps such as various spindles of machine tools or dry vacuum pumps, a portion where thermal expansion is large due to temperature rise, or It can operate under higher speed rotation and can be used for a long period of time at a location where a temperature gradient occurs inside the rolling device.
In the said embodiment, although the rolling bearing was illustrated as a rolling device, rolling devices, such as a linear motion guide device, may be sufficient.
Here, the cemented carbide has advantages that it is easy to process and cheaper than the ceramic material.

  Examples I1 to I10 which are rolling bearings based on the present invention by composing the inner and outer rings 1 and 2 and the rolling elements 3 with materials shown in Tables 25 and 26, and a comparison which is a rolling bearing for comparison. Examples i1 to i7 were prepared, and each rolling bearing was evaluated for high speed rotation and durability as described below. Each rolling bearing is an angular rolling bearing (model number: 7013C, inner diameter: 65 mm, outer diameter: 100 mm, width: 18 mm, contact angle: 15 °). In addition, each Example of Table 25 is an example which used the ceramic material for the rolling element, and Table 26 is an example which used the cemented carbide for the rolling element.

Here, in Table 25, silicon nitride and zirconia are ceramic materials having the following performance.
(1) Silicon nitride 1i:
Linear expansion coefficient: 3.4 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 0.41, Specific rigidity: 0.94 × 10 ⁸ (mm), Specific strength: 3.93 × 10 ⁷ mm
(2) Silicon nitride 2i:
Linear expansion coefficient: 3.0 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 0.46, Specific rigidity: 0.95 × 10 ⁸ (mm), Specific strength: 3.06 × 10 ⁷ mm
(3) Silicon nitride 3i:
Linear expansion coefficient: 2.8 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 0.40, Specific rigidity: 0.94 × 10 ⁸ (mm), Specific strength: 2.94 × 10 ⁷ mm
(4) Silicon nitride 4i:
Linear expansion coefficient: 5.4 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 0.33, Specific rigidity: 0.86 × 10 ⁸ (mm), Specific strength: 2.41 × 10 ⁷ mm
(5) Zirconia series 1i:
Linear expansion coefficient: 9.6 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 0.51, Specific rigidity: 0.47 × 10 ⁸ (mm), Specific strength: 1.73 × 10 ⁷ mm

In Table 26, cemented carbide is a cemented carbide having the following performance.
(1) Carbide 1i (WC-Co G1 made by Nippon Tungsten):
Linear expansion coefficient: 5.0 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 1.10, Specific rigidity: 0.38 × 10 ⁸ mm, Specific strength: 1.27 × 10 ⁷ mm
(2) Carbide 2i (WC-TiC-TaC-Co based HN05 made by Nippon Tungsten):
Linear expansion coefficient: 5.5 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 0.55, Specific rigidity: 0.41 × 10 ⁸ mm, Specific strength: 1.02 × 10 ⁷ mm
(3) Carbide 3i (Daijet Industry WC-Ni DN):
Linear expansion coefficient: 4.5 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 0.76, Specific rigidity: 0.41 × 10 ⁸ mm, Specific strength: 1.46 × 10 ⁷ mm

(4) Carbide 4i (WC-Ni-Cr-based M61U manufactured by Sumitomo Electric Industries):
Linear expansion coefficient: 4.4 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 0.92, Specific rigidity: 0.36 × 10 ⁸ mm, Specific strength: 1.95 × 10 ⁷ mm
(5) Carbide 5i (WC-Co-Ni-Cr type M4 manufactured by Sumitomo Electric Industries):
Linear expansion coefficient: 4.0 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 0.58, Specific rigidity: 0.41 × 10 ⁸ mm, Specific strength: 2.17 × 10 ⁷ mm
(6) Carbide 6i (WC-Co G30 made by Nippon Tungsten):
Linear expansion coefficient: 5.7 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 1.10, Specific rigidity: 0.38 × 10 ⁸ mm, Specific strength: 1.99 × 10 ⁷ mm
(7) Carbide 7i (WC-Ni-Cr-Mo type M45 manufactured by Fuji Dice):
Linear expansion coefficient: 6.1 × 10 ⁻⁶ (K ⁻¹ ), (Fracture toughness value / Vickers hardness): 0.83, Specific rigidity: 0.39 × 10 ⁸ mm), Specific strength: 2.25 × 10 ⁷ mm

SUJ2 has a linear expansion coefficient of 12.5 × 10 ⁻⁶ (K ⁻¹ ) (0 to 100 ° C.), a longitudinal elastic modulus of 208 (GPa), and a density of 7.83 (g / cm ³ ). .
SUS440C has a linear expansion coefficient of 10.1 × 10 ⁻⁶ (K ⁻¹ ) (0 to 100 ° C.), a longitudinal elastic modulus of 200 (GPa), and a density of 7.68 (g / cm ³ ). . And each rolling bearing for each test was assembled | attached by the back surface combination, respectively, and the preload in normal temperature was 700N. In either case, a nylon cage was used as the cage, and oil-air lubrication was performed using Super Highland 22 (VG22) as the lubricating oil (flow rate was 0.225 cc / hour).

High-speed rotation was evaluated using a bearing rotation tester manufactured by NSK (comprising a spindle structure with a back surface combination, although details are omitted). The outer ring 2 side is fixed to the housing 4 to constitute a support body, and the inner ring 1 is fixed to the shaft body 5 to constitute a mover that performs rotational motion.
The evaluation is performed at room temperature and in the atmosphere, with a preload set to 700 N before the test, while measuring the temperature of the outer diameter surface of the outer ring 2, the test is started from a rotational speed of 5000 min ⁻¹ , and 1000 rpm every 30 minutes. The rotational speed was increased, and the rotational speed at the time when the outer surface temperature of the outer ring 2 suddenly increased was taken as the limiting rotational speed, which was used as a reference value for evaluating high-speed rotational performance.
The evaluation results are also shown in Table 25 and Table 26. In addition, the high-speed rotability (limit rotational speed) of the rolling bearing in each example and comparative example is a relative value with the high-speed rotability (limit rotational speed) of Comparative Example i1 (Table 25) as 1. .

On the other hand, the durability evaluation test is performed using a bearing rotation tester manufactured by NSK, which is the same as the tester used in the evaluation of the high-speed rotation (limit rotation speed), at room temperature and in the atmosphere, and preloading is performed before the test. The test was conducted at a rotational speed of 15000 min ⁻¹ at 700 N, and the durability was evaluated based on the vibration value. Here, the time when the vibration value increased to five times the initial value was defined as the life of the rolling bearing.

The evaluation results are also shown in Table 25 and Table 26. In addition, the high-speed rotation property and durability (vibration life) of the rolling bearing in each example and comparative example are relative values where the high-speed rotation property and durability (vibration life) of Comparative Example i1 (Table 25) are set to 1, respectively. It is shown.
As shown in Table 25 and Table 26, the rolling bearings of the respective examples based on the present invention are remarkably improved in high-speed rotation and durability as compared with the comparative examples.

  Further, as the inner and outer rings 1 and 2, a material quenched and tempered into SUJ2 and SUS440C is used, and as the rolling element 3, a material quenched and tempered into SUJ2 and SUS440C or, for example, as shown in Table 25 and Table 26 Rolling bearings composed of ceramic materials and cemented carbides and combined with various linear expansion coefficient ratios were prepared to evaluate high-speed rotation and durability. Test conditions and evaluation conditions were the same as described above.

The durability and the high-speed rotation are shown as relative values where the durability (vibration life) and the high-speed rotation are 1 when the inner and outer rings 1 and 2 and the rolling element 3 are all made of SUJ2.
The result is shown in FIG.
Here, since the expansion of the inner ring 1 tends to promote the seizure and the low life by reducing the bearing clearance as compared with the expansion of the outer ring 2, the linear expansion of the rolling element 3 with respect to the linear expansion coefficient of the inner ring 1 is shown in FIG. 27. Based on the ratio of the coefficients, high-speed rotation performance (limit rotational speed) and durability (vibration life) were obtained.

  As can be seen from FIG. 27, the ratio of the linear expansion coefficient of the rolling element 3 to the linear expansion coefficient of the inner ring 1 is 0.45, which is twice as high as that of 0.5 or more. In addition, when 0.40 or less, the effect is improved and it is possible to ensure the stability. That is, it can be seen that at least the ratio of the linear expansion coefficient of the rolling element 3 to the linear expansion coefficient of the inner ring 1 is 0.45 or less, preferably 0.40 or less.

Further, the rolling element 3 is selected so that the ratio of the linear expansion coefficient of the rolling element 3 to the linear expansion coefficient of the inner ring 1 and the ratio of the linear expansion coefficient of the rolling element 3 to the linear expansion coefficient of the outer ring 2 are 0.45. did. For the selection, silicon nitride (Si ₃ N ₄ ) -based ceramic material is subjected to atmospheric pressure sintering, reaction sintering, or HIP (hot isostatic pressing), and the ratio between fracture toughness and Vickers hardness We made various prototypes with different values. And the test and evaluation about the durability of a bearing were implemented on the same conditions as the above-mentioned.

The durability is shown as a relative value with the durability (vibration life) being 1 when the inner and outer rings 1 and 2 and the rolling element 3 are all made of SUJ2.
FIG. 28 shows the result.
As can be seen from FIG. 28, when the ratio of the fracture toughness to the Vickers hardness of the rolling element 3 is 0.4 or more, the durability is improved twice or more compared to 0.35 or less, particularly 0.425 or more. It can be seen that the durability is remarkably improved in the case of. That is, it can be seen that the ratio of the fracture toughness to the Vickers hardness of the rolling element 3 is 0.4 or more, preferably 0.425 or more.
Further, it has been confirmed that the same results as in FIG. 28 can be obtained even when the rolling element 3 is made of a cemented carbide instead of the ceramic material.
As described above, it can be seen that the rolling bearing device according to the present invention is excellent in high-speed rotation performance (limit rotation speed) and has a long life.

[Embodiment 4]
FIG. 29 is a partial longitudinal sectional view showing the structure of a rolling bearing which is an embodiment of the rolling device of the present invention. The rolling bearing includes an outer ring 1, an inner ring 2, a plurality of balls 3 that are rotatably disposed between the outer ring 1 and the inner ring 2, and a resin crown-shaped cage that holds the plurality of balls 3. (Not shown). In addition, the outer ring | wheel 1 is corresponded to the needle | mover which is a structural requirement of this invention, and the inner ring | wheel 2 is equivalent to the support body which is a structural requirement of this invention.

The outer ring 1, the inner ring 2, and the ball 3 are all made of a ceramic material, and the ratio of the fracture toughness value (MPa · m ^1/2 ) to the Vickers hardness (GPa) of the ceramic material ([fracture toughness value ] / [Vickers hardness]) is 0.25 or more, and the specific strength is 1.2 × 10 ⁷ mm.
Since the rolling bearing of this embodiment is made of a ceramic material, it is lightweight and excellent in rigidity, wear resistance, and heat resistance. In addition, even under high-speed rotation, adhesion at the contact point is much less likely to occur and seizure is difficult compared to metal materials.

Further, since the value of [fracture toughness value] / [Vickers hardness] of the ceramic material is 0.25 or more, cracks are difficult to propagate on the surface or inside of the ceramic material, and peeling and wear are unlikely to occur. Therefore, the rolling bearing of the present embodiment has a long life even under a high load.
In particular, even when a radial load is supported, cracks hardly propagate on the surface or inside of the ceramic material in the outer ring having a load zone where the load concentrates, and peeling and wear are unlikely to occur. Therefore, it has a long life even under a condition where a high radial load is applied.

  Since the rolling bearing of the present embodiment has the excellent characteristics as described above, it can be used under a high load even at high speed, in a corrosive environment, and in a high temperature environment. Therefore, it can be suitably used for various spindles, various pumps, semiconductor manufacturing apparatuses (such as a conveying apparatus), machine tools, and turbines. However, it is a matter of course that the rolling bearing has a long life even when applied to any other device or application.

  In addition, this embodiment shows an example of this invention, Comprising: This invention is not limited to this embodiment. For example, in the present embodiment, a rolling bearing is exemplified as the rolling device, but the rolling device of the present invention can be applied to various other types of rolling devices. For example, the present invention can be suitably applied to other rolling devices such as a linear motion guide device, a ball screw, a linear motion bearing, and a linear bush.

Further, the rolling bearing of the rolling device of the present invention can be applied to various rolling bearings. For example, radial rolling bearings such as deep groove ball bearings, angular contact ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust type bearings such as thrust ball bearings and thrust roller bearings It is a rolling bearing.
Next, in the rolling bearing having substantially the same configuration as described above, various kinds of ceramic materials constituting the outer ring 1, the inner ring 2, and the ball 3 were prepared, and various evaluations were performed by a rotation test.

For the rolling bearings of Examples J1 to J28 and Comparative Examples j1 to j4, rolling bearings manufactured by NSK Ltd. (nominal number 6206, inner diameter 30 mm, outer diameter 62 mm, width 16 mm) were used. The outer ring, inner ring, and ball were made of ceramic materials as shown in Table 27 and Table 28. In addition, a fluorinated resin crown-shaped cage was used as the cage. In Tables 27 and 28, the ratio between the fracture toughness value (MPa · m ^1/2 ) and the Vickers hardness (GPa) of each ceramic material ([fracture toughness value] / [Vickers hardness]), The specific strength (× 10 ⁷ mm) is also shown.

The ceramic material used is as follows.
-Silicon nitride 1j: NPN-3, manufactured by Nippon Tungsten Co., Ltd.
・ Silicon nitride-based 2j: SAN-P, manufactured by Shinagawa White Brick Co., Ltd.
-Silicon nitride 3j: SN733 manufactured by Kyocera Corporation
・ Silicon nitride 4j: SINERAMICS, S / RBSN

・ Zirconia 1j: K701A, Z701N
・ Zirconia 2j: manufactured by Nippon Tungsten Co., Ltd., NPZ-2
-Zirconia 3j: NPZ-1 manufactured by Nippon Tungsten Co.
・ Zirconia 4j: KGS20, manufactured by Nippon Special Ceramics Co., Ltd.
・ Zirconia 5j: RZ601, manufactured by Sumitomo Electric
・ Zirconia 6j: K703, Z703
Zirconia 7j: Kyocera Corporation, Z21H0
・ Zirconia 8j: AZ-80GH, manufactured by Nippon Special Ceramics Co., Ltd.
・ Zirconia 9j: NPZ-3, manufactured by Nippon Tungsten Co., Ltd.
・ Zirconia 10j: NPZ-5 manufactured by Nippon Tungsten Co., Ltd.
・ Zirconia 11j: NGK Corporation, CZ-51

・ Alumina series 1j: HC2 manufactured by Nippon Special Ceramics Co., Ltd.
・ Alumina 2j: NAZ-83H, manufactured by Nippon Special Ceramics Co., Ltd.
Alumina 3j: AZ-93 manufactured by Saint-Gobain Norton
・ Alumina 4j: manufactured by Toshiba, AL-16
-Alumina 5j: Nippon Tungsten Co., NPA-2
Alumina 6j: KP-95 manufactured by Nippon Special Ceramics Co., Ltd.
-Silicon carbide type: NPS-1 manufactured by Nippon Tungsten Co., Ltd.
・ Silicon carbide particle-dispersed silicon nitride system: manufactured by Kubota Corporation, KN-101N
・ Silicon carbide whisker composite silicon nitride system: manufactured by Nisshi New Material, SNW
-Titanium boride type 1j: manufactured by Kubota Corporation, TB-901

Next, the evaluated contents and conditions of the rotation test will be described.
First, load resistance (limit load) will be described.
A rolling bearing 32 is mounted on a bearing rotation tester manufactured by NSK Ltd. as shown in FIG. 30, the initial radial load is 400 N, water 33 is used as a lubricant, and the rotational speed is 5000 min ⁻¹ at room temperature. It was rotated with. Then, the radial load was increased by 100 N every 6 hours, and the load resistance was evaluated using the radial load at the time when the vibration value detected by the vibration sensor 34 rapidly increased as the limit load.

In FIG. 30, reference numeral 30 denotes a rotating shaft, which is rotated by a motor (not shown). The ball bearing 31 is a support bearing for supporting the rotary shaft 30. Further, the test bearing 32 is rotated by the inner ring rotation by the rotating shaft 30, and the test load is loaded in the radial direction by an external load device (not shown).
The test results are summarized in Table 27 and Table 28. In addition, the load resistance (limit load) of the rolling bearing in each Example and Comparative Example is shown as a relative value when the load resistance (limit load) of Comparative Example j1 is 1.

Next, durability (life) will be described.
The rolling bearing was attached to a bearing rotation tester manufactured by NSK Ltd. similar to the above, and the radial load was 980 N, and water was used as a lubricant, and the rolling bearing was rotated at a rotational speed of 5000 min ⁻¹ at room temperature. The time when the vibration value increased to three times the initial value was defined as the life of the rolling bearing. The results are summarized in Table 27 and Table 28. In addition, durability (life) of the rolling bearing in each Example and Comparative Example is shown as a relative value when the durability (life) of Comparative Example j1 is 1.

In addition, the rotational speed in the above-mentioned two types of tests can be said to be a high-speed rotational test for a rolling bearing made of a ceramic material.
Next, the evaluation results of the rolling bearing in which the outer ring, the inner ring, and the ball are made of the same kind of ceramic material will be considered.
From the results of Examples J1 to J14, J20 to J28, and Comparative Examples j1 to j4, the specific strength is 1.2 × 10 ⁷ mm or more, and the larger the ratio between the fracture toughness value and the Vickers hardness, the more the rolling bearing. It can be seen that there is a tendency to have excellent load resistance and durability.

In Example J21, the ceramic material in which the ratio of the fracture toughness value (MPa · m ^1/2 ) to the Vickers hardness (GPa) is 0.25 or more is silicon carbide (SiC) having a particle size of 1 μm or less. Although it is an example which is silicon nitride (Si ₃ N ₄ ) contained, it can be seen that even when a rolling bearing is constituted by silicon nitride ceramics, it is particularly excellent in load resistance and durability.
Silicon nitride containing silicon carbide having a particle size of 1 μm or less is composed of 1 to 40% by mass of silicon carbide powder having a particle size of 1 μm or less and spinel (MgAl ₂ O ₄ ) / zirconia (ZrO ₂ ) powder 3 to 3 as a sintering aid. It is preferably obtained by sintering a powder mixture in which 20% by mass of silicon nitride powder is blended, and preferably has a structure in which silicon carbide particles are dispersed in the grains of silicon nitride particles and in grain boundaries.

As for the compounding quantity of the sintering auxiliary agent (spinel / zirconia) which occupies in a sintering raw material, 3-20 mass% is preferable. If it is less than 3% by mass, the sintering reaction cannot proceed efficiently, and there is a risk of insufficient densification of the sintered body, cracks tend to propagate, and the rolling bearing takes a relatively short time. May end up with a lifespan.
On the other hand, when the amount of the sintering aid in the sintering raw material exceeds 20% by mass, the residual glass phase at the grain boundary of the silicon nitride in the matrix increases, and mechanical properties such as strength and toughness are increased. Since the reduction is caused, the rolling bearing may end up in a relatively short time. In order to make it difficult for such problems to occur, the blending amount of the sintering aid in the sintering raw material is more preferably 5 to 15% by mass.

In addition, the amount ratio of the two components of spinel and zirconia constituting the sintering aid is spinel / zirconia = 1/2 to 2/1 (weight ratio) in order to express the auxiliary effect more effectively. Preferably there is. In addition, zirconia is a so-called partially stabilized zirconia containing about 1 to 2.8 mol% of yttria (Y ₂ O ₃ ) in order to suppress and prevent phase transition and the accompanying decrease in the sintering aid effect. Are preferably used.

  As the dispersed phase component, silicon carbide having a fine particle diameter of 1 μm or less is used. When applying such fine powder including nanometer level, it is possible to form a structure in which silicon carbide particles are distributed in the grain boundaries of silicon nitride matrix particles, and as described above, the dispersion effect is as follows. The separation and dropping of particles from the sliding surface are suppressed and prevented, the strength and toughness are improved, and the wear resistance is also improved, so that the rolling bearing can operate stably for a long time.

  The blending amount of the silicon carbide powder in the sintering raw material is preferably in the range of 1 to 40% by mass. When the amount is less than 1% by mass, the toughness of the silicon nitride matrix particles cannot be sufficiently increased as the dispersed phase, and the above-described effect of suppressing and preventing the separation and dropping of the particles from the sliding surface is not sufficient. On the other hand, if it exceeds 40% by mass, the silicon carbide particles tend to aggregate and increase the residual porosity, and as a result, the effect of improving the characteristics of the sintered body cannot be ensured. In order to make it difficult for such a problem to occur, the blending amount of the silicon carbide powder in the sintered raw material is more preferably 5 to 30% by mass.

  The sintering method of silicon nitride containing silicon carbide having a particle size of 1 μm or less is not particularly limited, but the sintering reaction is performed by heating and holding the pressure-formed body of the sintering raw material in an inert atmosphere. It is possible to apply an atmospheric pressure sintering method that performs the above. Moreover, if a sintered body obtained by atmospheric pressure sintering is subjected to hot isostatic pressing (HIP) as desired, higher density and mechanical properties are imparted.

Example J27 is an example of a rolling bearing in which the outer ring and the inner ring are made of the same kind of ceramic material, and the balls are made of a ceramic material different from the above. From this result, it is understood that when the ratio between the fracture toughness value and the Vickers hardness is as large as 0.25 or more, the rolling bearing is excellent in load resistance and durability.
FIG. 31 is a graph showing a part of the results of Tables 27 and 28 and the evaluation results of other rolling bearings (rolling bearings in which outer rings, inner rings, and balls are made of the same kind of ceramic material). Shown in The horizontal axis of the graph indicates the ratio between the fracture toughness value of the ceramic material and the Vickers hardness, the left vertical axis indicates the load resistance, and the right vertical axis indicates the durability. In the graph, data relating to load resistance is indicated by ◯, and data relating to durability is indicated by □.

As can be seen from the graph of FIG. 31, when the ratio between the fracture toughness value and the Vickers hardness is 0.25 or more, the load bearing and durability of the rolling bearing are excellent. Further, when it is 0.35 or more, load resistance and durability are more excellent, and when it is 0.40 or more, load resistance and durability are further excellent.
Next, an evaluation result of a rolling bearing in which the outer ring and the ball are made of the same kind of ceramic material and the inner ring is made of a ceramic material different from the above will be considered.

In Examples J15 to J19, the specific strength of the ceramic material is 1.2 × 10 ⁷ mm or more, and the ratio of the fracture toughness value to the Vickers hardness is 0.25 or more for all of the outer ring, the inner ring, and the ball. In addition, the ratio of the fracture toughness value of the ceramic material constituting the outer ring to the Vickers hardness and the ratio of the fracture toughness value of the ceramic material constituting the ball to the Vickers hardness are the fracture toughness value of the ceramic material constituting the inner ring. It is larger than the ratio of Vickers hardness.
As can be seen from Tables 27 and 28, such a rolling bearing is excellent in load resistance and durability.

FIG. 1 is a view showing a linear motion guide device which is an embodiment of a rolling device according to the present invention. FIG. 2 is a view for explaining a bending strength test of the guide rail shown in FIG. FIG. 3 is a diagram showing the test results of the bending strength tests of the examples and comparative examples shown in Table 1. FIG. 4 is a diagram showing test results of the bending strength tests of the examples and comparative examples shown in Table 2. FIG. 5 is a diagram showing the relationship between the surface roughness of the flat portion of the guide rail made of cermet and the breaking strength. FIG. 6 shows the thickness of the DLC film and the linear motion guide device when the guide rail of FIG. 1 is made of a ceramic material having a specific strength of 2.0 × 10 ⁷ mm or more and the surface of the rolling element is coated with the DLC film. It is a diagram which shows the relationship with durability. FIG. 7 shows the surface roughness of the DLC film and the linear motion guide device when the guide rail of FIG. 1 is made of a ceramic material having a specific strength of 2.0 × 10 ⁷ mm or more and the surface of the rolling element is coated with the DLC film. It is a diagram which shows the relationship with durability. FIG. 8 is a diagram showing the durability of the linear guide device when the rolling elements are made of materials having different hardnesses. FIG. 9 shows the hardness of the nitride film and the durability of the linear motion guide device when the guide rail of FIG. 1 is formed of a ceramic material having a specific strength of 2.0 × 10 ⁷ mm or more and the surface of the rolling element is covered with a nitride film. It is a diagram which shows the relationship with sex. FIG. 10 shows the surface roughness of the nitride film and the linear motion guide device when the guide rail of FIG. 1 is made of a ceramic material having a specific strength of 2.0 × 10 ⁷ mm or more and the surface of the rolling element is covered with the nitride film. It is a diagram which shows the relationship with durability. FIG. 11 shows the hardness of the composite carbide layer and the linear motion guide device when the guide rail of FIG. 1 is made of a ceramic material having a specific strength of 2.0 × 10 ⁷ mm or more and the surface of the rolling element is covered with the composite carbide layer. It is a diagram which shows the relationship with durability. FIG. 12 shows the surface roughness of the composite carbide layer and the linear motion guide when the guide rail of FIG. 1 is formed of a ceramic material having a specific strength of 2.0 × 10 ⁷ mm or more and the surface of the rolling element is covered with the composite carbide layer. It is a diagram which shows the relationship with durability of an apparatus. FIG. 13 shows the hardness of the boride film and the linear motion guide device when the guide rail of FIG. 1 is formed of a ceramic material having a specific strength of 2.0 × 10 ⁷ mm or more and the surface of the rolling element is covered with the boride film. It is a diagram which shows the relationship with durability. FIG. 14 shows the surface roughness of the boride film and the linear motion guide when the guide rail of FIG. 1 is made of a ceramic material having a specific strength of 2.0 × 10 ⁷ mm or more and the surface of the rolling element is covered with the boride film. It is a diagram which shows the relationship with durability of an apparatus. FIG. 15 is a plan view of a testing machine used for testing the durability of the linear motion guide device shown in FIG. FIG. 16 is a diagram showing the relationship between the surface roughness in the width direction of the rolling element rolling grooves and the amount of preload reduction. FIG. 17 is a diagram showing the relationship between the surface roughness in the longitudinal direction of the rolling element rolling groove and the preload reduction amount. FIG. 18 is a diagram showing the relationship between the Sk value of the rolling element rolling groove surface and the preload reduction amount. FIG. 19 is a diagram showing a life test result of the linear motion guide device shown in FIG. FIG. 20 is a diagram showing the repeated bending stress load test results of the linear motion guide device shown in FIG. FIG. 21 is a partial longitudinal sectional view showing a structure of a ball bearing which is an embodiment of the rolling device according to the present invention. FIG. 22 is a diagram showing the correlation between the specific strength of the ceramic material, the limit rotational speed and durability of the ball bearing. FIG. 23 is a view showing the relationship between the thermal shock value and bending strength of the ceramic material at 200 ° C. and the high temperature durability of the ball bearing. FIG. 24 is a diagram showing the relationship between the thermal shock value and bending strength of the ceramic material at 460 ° C. and the high temperature durability of the ball bearing. FIG. 25 is a diagram showing the correlation between the bending strength of boride cermets and the durability of ball bearings. FIG. 26 is a partial cross-sectional view showing a rolling bearing which is an embodiment of a rolling device according to the present invention. FIG. 27 is a diagram showing the relationship between the ratio of the linear expansion coefficient, high-speed rotability, and durability. FIG. 28 is a diagram showing the relationship between (fracture toughness value / Vickers hardness) and durability. FIG. 29 is a partial cross-sectional view showing the structure of a rolling bearing which is an embodiment of the rolling device according to the present invention. FIG. 30 is a sectional view showing the structure of a bearing rotation tester. FIG. 31 is a diagram showing the correlation between the ratio of the fracture toughness value and the Vickers hardness of the ceramic material, and the load bearing capacity and durability of the rolling bearing.

Claims (3)

A rolling element provided with a movable element that can rotate or linearly move, a support body that supports the movable element, and a plurality of rolling elements that are arranged to roll between the movable element and the support body. A moving device, wherein at least one of the mover, the support, and the rolling element is formed of any one of ceramic material, cermet, and cemented carbide, and the bending strength and density of the material The ratio of the linear expansion coefficient at normal temperature of the rolling element and the movable element is 0.45 or less, and the linear expansion coefficient of the rolling element and the support at normal temperature is 1.2 × 10 ⁷ mm or more. A rolling device having a ratio of 0.45 or less. The rolling device according to claim 1, wherein the rolling element is formed of a ceramic material having a ratio of a fracture toughness value (MPa · m ^1/2 ) to a Vickers hardness (GPa) of 0.40 or more. The rolling device according to claim 1, wherein the rolling element is formed of a cemented carbide having a ratio of a fracture toughness value (MPa · m ^1/2 ) to a Vickers hardness (GPa) of 0.40 or more.

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