JP2002168247A - Direct-acting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct-acting device capable of enhancing reliability in high-speed driving by suppressing heat generation associated with the driving, and capable of maintaining lubrication for a long time. SOLUTION: In the direct-acting device comprising an outside member, an inside member opposing the outside member via a gap, a plurality of rolling bodies arranged between the outside member and the inside member so as to be capable of freely rolling and for relatively moving the outside member and the inside member; a sealing device for sealing the opening of the gap, and a lubricant-feeding member disposed adjacent to the sealing device and made of a synthetic resin solidified with containing a lubricant, the direct-acting device is characterized in that the lubricant-feeding member contains a solid lubricant of which the thermal conductivity is not less than 20 W/m.K.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion device such as a linear guide device and a ball screw, and more particularly to suppressing a temperature rise during operation and improving reliability at high speed running and improving lubrication life. It relates to a linear motion device.

[0002]

2. Description of the Prior Art As this type of conventional linear motion device, there is a linear guide device disclosed in JP-A 9-25933 discloses for example by the present applicant. In this linear guide device, a lubricant supply member is disposed near the lip of the seal device. The lubricant supply member is obtained by molding a mixture composed of a polyolefin-based synthetic resin such as polyethylene and a lubricant (lubricating oil or grease) into a predetermined shape by injection molding or the like, and solidified in a state containing the lubricant. cage, allowing the lubricating long oozes lubricant gradually from its surface.

[0003]

However, in the above-mentioned lubricant supply member, since both the polyethylene and the lubricant have low thermal conductivity, the lubricant supply member and the guide rail which are arranged close to each other as the slider travels. As a result, heat is accumulated in the sliding portion, and local heat is easily generated. The traveling speed of the slider tends to increase,
Accordingly, the temperature rise due to such local heat generation is also increasing. Since the lubricant supply member is based on a resin component, the resin component softens at high temperatures,
Or hindered the traveling sliding resistance is high, the mechanical strength is likely to failure decreases. In addition, the lubricant supply member has a problem that the lubricant is depleted earlier because the amount of lubricant contained therein increases as the temperature increases.

An object of the present invention is to solve the above-mentioned problems, that is, to provide a linear motion device which suppresses heat generation during operation to improve reliability during high-speed running and maintains lubrication for a long time. The purpose is to do.

[0005]

In order to achieve the above object, the present invention provides an outer member, an inner member opposed to the outer member via a gap, and the outer member and the inner member. A plurality of rolling elements disposed to be rotatable between the outer member and the inner member, and a seal device for sealing an opening of the gap; And a lubricant supply member made of a synthetic resin solidified in a state containing a lubricant, wherein the lubricant supply member has a heat conductivity of 20 W / m · K or more. Provided is a linear motion device characterized by containing a solid lubricant.

In the linear motion device, since the lubricant supply member contains a solid lubricant having a thermal conductivity of 20 W / m · K or more, the thermal conductivity of the lubricant supply member is increased, and the lubricant supply member is operated. Effectively dissipates the generated heat to the outside. As a result, the lubricant supply member is not deformed or damaged even during high-speed running, and the function of gradually releasing the lubricant inherent in the lubricant supply member is also maintained. To ensure good lubrication performance over a long period of time. The present invention is based on such findings.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

[0008] As the linear motion apparatus according to the present invention, may be exemplified linear guide and the ball screw device described in detail the structure below.

(Linear Guide Device) As shown in FIG. 1, the linear guide has a guide rail 10 which has rolling element rolling grooves 13A and 13B on its outer surface and extends in the axial direction, and is assembled across the guide rail 10. Slider 20 provided.

The slider 20 comprises a slider body 20A and end caps 20B attached to both ends of the slider body. The slider body 20A faces rolling elements rolling grooves 13A and 13B of the guide rail 10 on inner side surfaces of both sleeves. And a rolling element return path extending axially through the thick portion of the sleeve. The end cap 20B has a curved path (not shown) that connects the rolling element rolling groove of the slider body 20A and a rolling element return path parallel to the rolling element rolling groove, and the rolling element rolling groove, the rolling element return path, and the like. A rolling element circulation circuit is formed by the curved paths at both ends. Many rolling elements made of, for example, steel balls are loaded in the rolling element circulation circuit. In the figure, reference numeral 27 denotes a grease nipple.

The end cap 20B is an injection-molded product made of a synthetic resin and has a substantially U-shaped cross section. As shown in FIG. 2 which is a perspective view showing the assembled state of the end portion of the slider 20, the reinforcing plate 21 and the lubricating plate are provided on the outer surfaces of both end caps 20B in order from the side closer to the end cap 20B. The agent supply member 22 and the side seal 23 are fixed in an overlapping state.

[0012] reinforcing plate 21 is a steel plate of approximately U-shape corresponding to the outer shape of the end cap 20B, Its both sleeves, through holes 21a through which the mounting screws 26, together with 21b is formed, both A through-hole 21c for a grease nipple is formed in a connecting portion connecting the sleeve portions. The reinforcing plate 21 is not in contact with the guide rail 10.

Further, the side seal 23, composed of a steel plate of substantially U-shaped to match the contour of the end cap 20B, a shape similar with the steel sheet and the nitrile rubber are integrally molded on the outer surface thereof Have been. The lip portion L of the side seal 23 that comes into contact with the guide rail 10 has an inner surface guided along the cross-sectional shape of the guide rail 10 so that a gap between the slider 20 and the guide rail 10 can be sealed. The rail 10 is formed in a shape that allows sliding contact with the upper surface 10a and the outer surface 10b, as well as the rolling element rolling grooves 13A and 13B. In addition, this side seal 23
Also, through holes 23a and 23b for mounting screw penetration and a through hole 23c for grease nipple are formed.

The lubricant supply member 22 sandwiched between the reinforcing plate 21 and the side seals 23
As shown in FIG. 5, the end cap 20B is formed in a substantially U-shape in accordance with the outer shape, and the inner surface of the U-shape is formed along the upper surface 10a and the side surface 10b of the guide rail 10, and projections 22a corresponding to the rolling grooves 13B on the guide rail 10, 22b, and projections 22c corresponding to the rolling grooves 13A of the lower, 22 d is a cross-sectional outer shape of the guide rails 10 are formed respectively Be consistent. Further, the lubricant supply member 22 is formed with 22e and 22f for penetrating the mounting screw and a through hole 22g for the grease nipple.

In FIG. 2, reference numerals 25a to 25c
Is a ring-shaped sleeve member.

(Ball Screw Device) In the ball screw device, as shown in FIG. 4, a ball nut 30 is disposed so as to include a screw shaft 31, and a thread groove 30 a formed on the inner periphery of the ball nut 30 is provided. A plurality of balls 3 are provided between a screw groove 31b formed on the outer periphery of the screw shaft 31 opposed thereto.
2 are arranged so as to roll freely.

One end of the ball nut 30 (right end in the figure)
, A cylindrical seal cap 34 is attached by a bolt 35 via a lubricant supply member 33. Sleeves 36 are respectively interposed on the outer periphery of the shaft of the bolt 35. A labyrinth seal 37 is attached to the end of the seal cap 34 to prevent foreign matter such as dust from entering through the space between the screw shaft 31 and the seal cap 34. A thin groove 33a is formed on the outer periphery of the lubricant supply member 33, and is pressed radially toward the outer periphery of the screw shaft 31 by a garter spring 38 disposed at a constant pressure. Therefore, even if the inner peripheral surface of the lubricant supply member 33 is worn due to, for example, long-term operation, appropriate contact with the screw shaft 31 is always maintained, and good lubrication is ensured.

In the above linear guide device and ball screw device, each of the lubricant supply members 22 and 33 (hereinafter referred to as symbols) is made of a synthetic resin solidified in a state containing a lubricant and a solid lubricant. This lubricant supply member heats and plasticizes a molding material obtained by mixing and mixing a lubricant and a solid lubricant with various additives to a synthetic resin at a temperature equal to or higher than the melting point of the synthetic resin, and is then filled into a predetermined mold. Obtained by cooling.

The lubricant and the synthetic resin are not particularly limited, but the synthetic resin is appropriately selected from the group of polyolefin resins having basically the same chemical structure, such as polyethylene, polypropylene, polybutylene and polymethylpentene. it can.

As the lubricant, paraffinic hydrocarbon oils such as poly α-olefin oil, naphthenic hydrocarbon oils, mineral oils, ether oils such as dialkyl diphenyl ether oils, ester oils such as phthalic acid esters, etc. are used alone. Or in the form of a mixed oil. In addition, any known antioxidants, rust inhibitors,
Various additives such as an antiwear agent, a defoaming agent, and an extreme pressure agent may be added.

The solid lubricant is not particularly limited as long as it has a thermal conductivity of 20 W / m · K or more. For example, graphite (graphite) (thermal conductivity)
100-150 W / mK), boron nitride (h-BN) (50-85
W / m · K) or the like can be used. These can be used in the form of fibers, whiskers, or the like, in addition to particles. In the present invention, since the lubricant supply member contains a solid lubricant, a lubricating action by the solid lubricant is added in addition to the lubricant, and good lubrication performance can be obtained.

The composition ratio of the lubricant supply member is 10 to 45% by weight of a polyolefin resin, 85 to 50% by weight of a lubricant, and 5 to 25% by weight of a solid lubricant based on the total weight. If the content of the polyolefin resin is less than 10% by weight, a certain level of hardness and strength cannot be obtained, and it becomes difficult to maintain the initial shape when a load is applied due to running of a linear motion device. The possibility of causing defects such as deformation is increased. On the other hand, when the polyolefin resin exceeds 45% by weight, the content of the lubricant is relatively reduced, and the supply of the lubricant to the inside of the linear motion device is correspondingly reduced, and the life of the bearing is shortened. When the solid lubricant is less than 5% by weight, the effect of increasing the thermal conductivity of the lubricant supply member is small,
On the other hand, when the content exceeds 25% by weight, the content of the lubricant is relatively reduced, and the supply of the lubricant to the inside of the linear motion device is correspondingly reduced, and the life of the linear motion device is shortened.

The above synthetic resin groups have the same basic structure but different average molecular weights, ranging from 700 to 5 × 10 ⁶ . In use, those classified into wax having an average molecular weight 700 to 1 × 10 ^4, average molecular weight 1 × 10 ⁴ ~1 × 1
0 relatively low molecular weight of ⁶ ones, average molecular weight 1 × 10 ⁶ ~5 × 1
0 ⁶ those ultra high molecular weight, used alone or in optionally. For example, a lubricant supply member having a certain degree of mechanical strength, a lubricant supply capacity, and an oil retaining property can be obtained by a combination of a lubricant having a relatively low molecular weight and a lubricant.
Also, if a part of this relatively low molecular weight is replaced with a wax classified, the difference in molecular weight between the wax classified and the lubricant is small, so the affinity with the lubricant is increased, As a result, the oil retaining property of the lubricant supply member is improved, and the lubricant can be supplied for a long period of time. However, on the other hand, the mechanical strength decreases. As the wax, in addition to a polyolefin-based resin such as polyethylene wax, a hydrocarbon-based wax having a melting point in the range of 100 to 130 ° C. or more (for example, a paraffin-based synthetic wax) can be used. On the other hand, if some of the relatively low molecular weight products are replaced with ultra high molecular weight ones, the difference in molecular weight between the ultra high molecular weight type and the lubricant will be large, and the affinity with the lubricant will be low. As a result, the oil retention is reduced, and the oozing of the lubricant from the lubricant supply member is accelerated. Thereby, the time required to reach the limit amount of the lubricant that can be supplied from the lubricant supply member is shortened, and the life of the bearing is shortened. However, the mechanical strength is improved.

In consideration of the balance between moldability, mechanical strength, oil retention, and lubricant supply, the composition ratio of the lubricant supply member is 0 to 5% by weight, which is classified as wax, and has a relatively low molecular weight. 8 to 43% by weight, ultra high molecular weight 2
It is practically preferable that the amount of the three resins is 15 to 45% by weight, that is, 10 to 45% by weight.

As an index of the mechanical strength, the hardness [HD _A (durometer hardness using scale A)] of the lubricant supply composition is preferably in the range of 65 to 85, and 70 to 80.
Is more preferably within the range. Hardness [HD _A ]
If it is less than 65, it is weak in strength and may be damaged by running of the linear motion device. On the other hand, hardness [HD _A ]
If it exceeds 85, the resistance of the linear motion device during traveling increases, thereby increasing the torque of the linear motion device,
There is a risk that the heat generated by the linear motion device, particularly at the sliding portion, will increase.

In order to improve the mechanical strength of the lubricant supply member, the following thermoplastic resin and thermosetting resin may be added to the above-mentioned polyolefin resin.

As the thermoplastic resin, resins such as polyamide, polycarbonate, polybutylene terephthalate, polyphenylene sulfide, polyether sulfone, polyether ether ketone, polyamide imide, polystyrene and ABS resin can be used.

As the thermosetting resin, resins such as unsaturated polyester resin, urea resin, melanin resin, phenol resin, polyimide resin and epoxy resin can be used.

These resins may be used alone or as a mixture. In order to disperse the polyolefin resin and the other resin in a more uniform state, a suitable compatibilizer may be added as needed.

Similarly, in order to improve the mechanical strength,
A filler may be added. For example, calcium carbonate whiskers, magnesium carbonate whiskers, potassium titanate whiskers, inorganic whiskers such as aluminum borate whiskers, inorganic fibers such as glass fibers and metal fibers, and those obtained by braiding these into a cloth, or aramid fibers, Organic fibers such as polyester fibers and the like and braided cloths may be added.

Further, in order to prevent deterioration of the polyolefin resin due to heat, N, N'-diphenyl-p-phenyldiamine, 2,2'-methylenebis (4-ethyl-
Antioxidants such as 6-t-butylphenol), and 2-hydroxy-4-n-
Octoxybenzophenone, 2- (2'-hydroxy -
An ultraviolet absorber such as 3'-t-butyl-5'-methyl-phenyl) -5-chlorobenzotriazole may be added.

The additive amount of the additives other than the above-mentioned polyolefin resin, lubricant and solid lubricant should be not more than 20% by weight of the total amount of the lubricant supply member as a whole. It is preferable in maintaining.

As the synthetic resin which can be used in the present invention, in addition to those based on the polyolefin-based resin described above, any thermoplastic resin which can be injection-molded can be used. For example, polyester-based elastomers, polyamide-based elastomers, and the like can be used.

In addition to the thermoplastic resins, thermosetting resins such as polyurethane and polyurea elastomers can be used. In the case of polyurethane, grease is used as a lubricant and becomes a reaction raw material. After uniformly mixing the or a urethane prepolymer containing an isocyanate group and the amine-based curing agent with the grease, the two mixtures are further mixed and filled into a lubricant supply member forming mold. The mixture is heated and reacted accordingly, and cured with grease contained. In the case of polyurea, an amine component consisting of a mixture of an aromatic polyamine compound containing a soft segment in the molecular chain and an aromatic diamine is uniformly mixed with a lubricating oil compatible therewith or a grease based on the lubricating oil. The resulting mixture is further mixed with a polyisocyanate component, and the mixture is filled into a molding die. The mixture is heated and reacted as needed, and cured with a lubricant contained.

[0035]

The present invention will be further described with reference to the following examples. However, the present invention is not limited to the following.

(Preparation of molding raw materials) 10% by weight of high-density polyethylene (classified into relatively low molecular weight), 12.5% by weight of ultra-high molecular weight polyethylene (classified in ultra-high molecular weight), and 2.5% by weight of polyethylene wax (classified in wax) % Resin was mixed with 8% by weight of graphite powder and 67% by weight of mineral oil to prepare a molding material A. A molding material B was prepared in the same manner except that the graphite powder of the molding material A was changed to boron nitride (h-BN). Further, a resin comprising 10% by weight of high-density polyethylene (classified as a relatively low molecular weight), 12.5% by weight of ultra-high molecular weight polyethylene (classified as an ultra-high molecular weight), and 2.5% by weight of polyethylene wax (classified as a wax);
A raw material C was prepared by mixing 75% by weight of mineral oil.

(Measurement of Thermal Conductivity) The above-mentioned molding raw materials A, B and C were melted, filled in a predetermined mold, and then cooled to form a test piece. Then, to measure the thermal conductivity at room temperature by laser flash method for each test piece. Table 1 shows the results. In the table, the test piece using the forming raw material A is Example 1, the test piece using the forming raw material B is Example 2, and the test piece using the forming raw material C is Comparative Example 1.

[0038]

[Table 1]

As shown in Table 1, it was confirmed that the thermal conductivity of the test piece containing the graphite powder was significantly increased.

(Linear guide running test) Further, using the molding raw materials A, B and C,
The lubricant supply member shown in FIG. 3 was produced by an injection molding machine described in No. 793 with an improved hopper. And
The following running test was performed using the linear guide device (LS15) shown in FIG. In addition, the linear guide device incorporating the lubricant supply member using the molding raw material A is Example 1, the linear guide device incorporating the lubricant supply member using the molding material B is Example 2, and the lubricant supply member using the molding material C is incorporated. The linear guide device is referred to as Comparative Example 1.

The test was performed at feed rates of 10 mm / s, 20 mm / s, and 50 mm / s.
At s, 100 mm / s, 500 mm / s, and 1000 mm / s, the dynamic friction force was measured when the lubricant supply member was attached to the linear guide device and when it was not attached, and the difference in dynamic friction between the lubricant supply member only was determined from the difference. Seeking power. Note that one lubricant supply member was attached to each end of the slider (see FIG. 2), and the slider was run with a preload Z1 (1.47 N) applied. Table 2 shows the kinetic frictional force at each feed rate. The kinetic frictional force of only the lubricant supply member of Example 1 at the feed rate of 10 mm / s is set to 1, and the relative value is shown.

[0042]

[Table 2]

At each feed rate, the temperature rise of the guide rail from room temperature was measured. Table 3 shows the results.

[0044]

[Table 3]

As can be seen from Tables 2 and 3, in each of the examples in which the graphite powder was contained in the lubricant supply member, the kinetic frictional force and the temperature were small even when the feed speed was high, and the stability at high speed running was high. It was confirmed that.

[0046]

As described above, the linear motion device of the present invention is provided with a lubricant supply member containing a solid lubricant having a thermal conductivity of 20 W / m · K or more. The heat radiation effect is enhanced, the lubricant supply member is not deformed or damaged even at high speed running, and the function of gradually releasing the lubricant inherent in the lubricant supply member is also maintained. The lubrication effect is also added to ensure good lubrication performance over a long period of time.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a linear guide device which is an embodiment of a linear motion device according to the present invention.

FIG. 2 is an exploded view showing a configuration of a slider including a lubricant supply member in the linear guide device shown in FIG.

FIG. 3 is a perspective view of the lubricant supply member shown in FIG. 2;

FIG. 4 is a sectional view of a main part showing a ball screw device which is another embodiment of the linear motion device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Guide rail 20 Slider 21 Reinforcement plate 22 Lubricant supply member 23 Side seal 30 Ball nut 31 Screw shaft 32 Ball 33 Lubricant supply member 34 Seal cap 35 Bolt 36 Sleeve 37 Labyrinth seal

Claims (1)

[Claims] [1 claim] an outer member, an inner member that face each other with a gap to the external side member, rollably disposed between said inner member and said outer member, said outer A plurality of rolling elements for relatively moving a member and the inner member; a sealing device for sealing the opening of the gap; and a synthetic resin disposed in close proximity to the sealing device and solidified in a state containing a lubricant. Wherein the lubricant supply member contains a solid lubricant having a thermal conductivity of 20 W / m · K or more.