JPH02294423A - Sliding material and method for treating surface thereof - Google Patents

Abstract

PURPOSE:To easily provide plural minute and smooth curved dent parts with wear resistance improved on the surface by blowing gas jet while melting surface of an iron series alloy-made sliding material with high-density energy heat source to form minute dent parts and quench-hardening the parts surrounding the above dent parts. CONSTITUTION:Converging concentrated plasma arc 11 as high density energy heat source is generated with the power source 10 between the above sliding material 1 and electrode 6, and the surface of the sliding material 1 is locally and rapidly heated to locally and rapidly melt this position by minute depth. At the same time, a part for a large part of the above molten metal is blown off with the gas jet of plasma gas 8 and shield gas 9 and the smooth curved- shape minute dent parts 2 are formed on the surface and the surface of dent part 2 becomes rapid cooled and resolidified fine structure part 3 to form the quenched-hardening part 4 surrounding this. Successively, spatter 12 and protected film 13, etc., stuck to the surface of the sliding material 1 are removed with shot blast treatment, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a ferrous alloy sliding material and a surface treatment method thereof, and is particularly applicable to automobile engines, hydraulic equipment, air conditioning equipment, and the like used under high load conditions. The present invention relates to a sliding material suitable for improving the wear resistance of sliding surfaces of compression equipment, etc., and a surface treatment method thereof.

[Conventional technology]

As a surface treatment method for sliding materials, Japanese Patent Application Laid-Open No. 62-1925
The techniques described in Japanese Patent Application Laid-open No. 34 and Japanese Patent Application Laid-Open No. 63-79940 are known. The former is a sliding material and its surface treatment method characterized by having recesses surrounded by a chill layer in a scattered manner, and the periphery of the recesses protruding by a predetermined amount from the sliding surface. be. In addition, the latter can be achieved by melting only the surface portion of the cast iron sliding material using a high-density energy heat source to generate a blowhole, and by filling the blowhole with highly alloyed material powder and remelting it, the cast iron surface is melted. This is a surface treatment method for highly alloying.

In addition, JP-A No. 62-256960, JP-A No. 62-253779, JP-A No. 62-211393
A method is known, such as the one disclosed in Japanese Patent Publication No. 2003-12901, in which fine dents are formed in the form of scattered dots on the surface of a sliding material using a high-density energy heat source. [Problem to be solved by the invention] Of the prior art disclosed in the above publication,
The technique disclosed in Japanese Patent No. 2-192534 is that a large number of recesses are provided on the surface of a sliding material in a scattered manner, each of which is made of a chill layer and whose periphery protrudes by a predetermined amount from the surface of the sliding material. However, as is clear from the above characteristics, if the lubricating oil is not retained on the surface of the sliding material or the lubricating oil that was retained is consumed or lost, Only the protruding parts around the edges of the many recesses bear the sliding load. Furthermore, since the sliding contact area at the protruding portion of the periphery of the recess is extremely small, as is clear from the shape and distribution of the recess, the sliding surface pressure of the protruding portion is also extremely large. There is a high risk that seizing and adhesion will occur rapidly and the wear resistance of the sliding material will be impaired.

The technique disclosed in JP-A No. 63-79940 melts the surface of a cast iron sliding material using a high-density energy heat source to generate blowholes in the molten metal and on the surface thereof. It is filled with highly alloyed material powder and melted again to highly alloy only the cast iron surface. In this technique, a large number of holes and recesses are formed on the surface of the cast iron material and its surface layer in the first step, but it does not disclose that the holes and recesses are actively used as oil reservoirs. Since these holes and recesses are used as filling spaces for the highly alloyed material powder, no recesses remain on the sliding surface finally obtained. Therefore, this known example does not disclose a surface treatment technique for forming a recess for an oil reservoir on the surface of a cast iron material.

In addition, a method has been disclosed in which the surface of a sliding material is rapidly melted using a high-density energy heat source and a large number of recesses are formed by removing the molten metal. However, all of these methods are only disclosed as techniques for forming recesses, and none disclose the effect of quench hardening accompanying heat treatment. The sliding surface of the sliding material supplies lubricant and has better wear resistance if it is made of a hard material, but none of these known examples mention hardening treatment of the sliding surface. .

An object of the present invention is to provide a sliding surface with a large number of recesses that hold lubricant, and to provide a sliding member with a hardness higher than that of the base material, which is less prone to wear, and a surface of the base material. The purpose of the present invention is to provide a surface treatment method for forming such a sliding contact surface. [Means for solving the problem] The above problem is solved by rapidly heating the surface of a sliding material made of iron-based alloy using a concentrated high-density energy heat source, and heating the surface of the sliding material locally and minutely. A sliding material characterized in that, at the same time as the molten metal is melted, a gas jet is blown onto the molten metal to form a small/JX recess, and the portion surrounding the recess is quenched and hardened as a result of the rapid heating. This is achieved through surface treatment methods. In addition, the surface of the ferrous alloy sliding material is rapidly heated using a convergent high-density energy heat source, and the surface of the sliding material is locally melted to a very small depth, and at the same time, the molten metal is cooled. The surface treatment method for a sliding material may be characterized in that a part or most of the molten metal is removed by spraying a cleaning liquid to form minute recesses on the surface of the sliding material. The surface of a sliding metal material is rapidly heated using a concentrated high-density energy heat source, and the surface of the sliding material is locally melted to a minute depth, and at the same time, oxidizing gas or A sliding material characterized in that a part or most of the molten metal is oxidized by spraying a liquid, and then the oxide is removed by an appropriate means to form minute recesses on the surface of the sliding material. It can also be used as a surface treatment method for moving materials. A first step of finishing the surface of a sliding material made of an iron-based alloy into a roughly final shape, a second step of forming a protective film to prevent molten metal from adhering to the surface of the sliding material, and a second step of forming a protective film on the surface of the sliding material to prevent adhesion of molten metal to the surface of the sliding material. A third step of rapidly melting locally and to a minute depth using a high-density energy heat source and removing a part or most of the molten metal, and a protective coating on the surface of the sliding material, molten metal and A fourth step of removing oxides and finishing the sliding surface may be provided as a surface treatment method for sliding materials. A minute recess is formed in at least a portion of the sliding surface;
The surface of the recess has a curved surface, the surface of the recess has a fine rapidly cooled and resolidified structure, and a hardened structure is formed to surround the resolidified structure. The above problems can also be achieved by the special sliding material.
A minute recess with a curved surface is formed in at least a part of the sliding surface, and the surface of the recess is curved, and the surface of the recess has a microscopic quenched recess. It may be used as a sliding material characterized by having a solidified structure and by retaining a substance effective in improving sliding performance in the recessed portions. A bearing member for a rotating body, in which a ring-shaped member made of an iron-based alloy with a sliding surface is fitted to the shaft or bearing, and the sliding surface of the ring-shaped member is hard and smooth. comprising a surface and a plurality of minute recesses;
It may also be used as a bearing member with the following characteristics. The sliding surface provided on a part of the rotating shaft is a hard smooth surface,
The rotating shaft may have a large number of groove-like recesses formed on the smooth surface substantially parallel to the axis of the rotating shaft, and the recesses serve as lubricant holding parts. In addition, while moving a pulsating high-density energy heat source whose output heat quantity fluctuates periodically on the surface of a sliding member made of iron-based alloy,
The heat source melts the surface locally and to a very small depth, and at the same time, a part or most of the molten metal is removed by an appropriate means, and a large number of minute recesses are formed in the surface in the form of broken lines or It can also be used as a surface treatment method for sliding materials, which is characterized by discontinuous formation. Claims 2, 3, and 4 further comprising a step of hardening the surface of the sliding material by a predetermined depth from the surface.
, 6, 7, and 8 may also be used. [Function] If an iron-based alloy containing 0.2% or more of carbon element is heated above the martensitic transformation point (approximately 790'C) and then rapidly cooled, it will be quenched and hardened by martensitic transformation. Focused high-density energy heat sources, such as laser beams, electron beams, and light beams. plasma arc,
The surface of the sliding member made of an iron-based alloy is rapidly heated to a temperature higher than the melting temperature of the sliding member by an appropriate high-density energy heat source selected from plasma jets, etc. melts only to a very small depth. At the same time, part or most of the molten metal is removed by the gas or liquid flow, forming minute recesses on the surface of the sliding member. Further, particles of molten metal (so-called spatter) adhering to the non-melting surface of the sliding member are removed by appropriate means such as shot blasting, shot peening, etching, etc. Through the above process, the spatter that was attached to the surface of the sliding member,
When dust, dirt, and oxides are thoroughly removed, minute and smoothly curved recesses are formed on the surface of the sliding member, and the surface of the recess becomes a microstructure that has been rapidly cooled and resolidified. In addition, in iron-based alloys containing 0.2% or more of carbon element, after the surface of the sliding member is rapidly heated to a temperature equal to or higher than the martensitic transformation point in the above-mentioned surface treatment process,
Since the heated part is rapidly cooled by the phenomenon of heat conduction around the heated part, the parts heated above the martensitic transformation point, centering on the heated part, are quenched and hardened. The amount of human heat required by the surface treatment method of the present invention, in which local parts of the sliding member are rapidly heated and rapidly cooled by a high-density energy heat source, is extremely small.
In addition, because the local area is rapidly heated and cooled in a short period of time, thermal deformation and thermal strain of the heated area that occurs during heat treatment can be minimized. Furthermore, if an oxidizing gas such as air is blown onto the molten metal when the surface of the sliding member is locally melted to a minute depth by a high-density energy heat source, most of the molten metal rapidly transforms into oxides. Metal oxides obtained by melting metals and rapidly oxidizing them are porous and brittle, so they can be easily and reliably removed by appropriate means. If the oxide is thoroughly removed by an appropriate means, such as shot blasting, a smooth curved recess approximately corresponding to the molten shape will be formed, and the surface of the recess will have a fine structure that has been rapidly cooled and resolidified. Become. The recesses, which have a smooth, fine structure and a curved shape, have good compatibility with substances that improve sliding properties, such as lubricating oil, so they have excellent lubricating oil retention performance. Also,
The lubricant retention performance of each recess is further improved by dividing the fine recesses formed on the surface of the sliding member into a large number of fine recesses and making them dotted, broken line, or discontinuous. do. In addition, the surface of the sliding member is locally melted to a minute depth by a high-density energy heat source, and at the same time, appropriate means,
After a part or most of the molten metal is removed by the method or process and minute recesses are formed on the surface of the sliding member, the surface of the sliding member is treated with an appropriate method such as carburizing, nitriding, plating, etc. A surface treatment method for sliding materials that is surface hardened is also effective. This treatment method is effective for improving the sliding properties of mild steel materials with a carbon content of 0.2% or less, stainless steel, aluminum alloys, titanium alloys, steel alloys, etc., which are difficult to quench and harden. By the surface treatment method of the present invention, the minute recesses formed on the surface of the sliding member are determined by the shape of the molten metal on the surface of the sliding member formed by the high-density energy heat source, as described above. Furthermore, the shape of the molten metal is uniquely determined by the thermal characteristics of the material to be heated and the heating conditions of the high-density energy heat source. That is, the surface treatment method of the present invention creates minute recesses in the surface of the sliding member at appropriate positions and shapes by controlling the heating conditions, including the speed and direction of movement of the high-density energy heat source relative to the surface to be treated. Form.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the surface treatment method for a sliding member of the present invention. 2 and 3 show details of a cross section in the treatment direction and a cross section perpendicular to the treatment direction of the surface of a sliding member treated by the surface treatment method shown in FIG. 1. In the figure, a similarly cylindrical nozzle electrode 7 is installed concentrically inside a plasma torch S having an approximately cylindrical shape, with its tip having an opening slightly protruding from the end opening of the plasma torch 5. A rod-shaped electrode 6 is further installed concentrically within the electrode 7, with its tip positioned inside the opening of the nozzle electrode 7. The electrode 6 is connected to a plasma arc generating power source 10, and the other end of the power source 10 is connected to the base material portion of the sliding material 1. The sliding material 1 is finished to a substantially approximate final shape and surface roughness, and a protective coating 13 is formed by coating ceramic or graphite on the surface. Shielding gas 9 is supplied to the cylindrical space formed by the inner periphery of the plasma torch 5 and the outer periphery of the nozzle electrode 7, and the cylindrical space formed by the inner periphery of the nozzle electrode 7 and the outer periphery of the electrode 6 is supplied with shielding gas 9. A plasma gas 8 is supplied to.

Sliding material 1 and electrode 6 are connected by power source 10 for plasma arc generation.
When a plasma arc generation voltage is applied between the sliding member 1 and the electrode 6, a plasma arc 11, which is a high-density energy heat source, is generated between the sliding material 1 and the electrode 6. The surface of the sliding material 1 made of materials such as carbon steel, alloy steel, and cast iron containing 0.2% or more of the carbon element is locally and rapidly heated by the plasma arc 11, which is a concentrated high-density energy heat source. Then, the surface of the sliding material 1 melts locally and rapidly to a very small depth.
The melting depth may be about 0.01 to 0.5 degrees. At the same time, a part or most of the molten metal is blown off by the pressure of the gas jets of plasma gas 8 and shielding gas 9, forming minute recesses 2 with smooth curved surfaces, and the surface of the recesses. becomes a microstructure portion 3 which is rapidly cooled and resolidified, and a quench hardened portion 4 surrounding the microstructure portion 3 is formed. The plasma arc 11 is sufficiently converged and concentrated by the small diameter opening at the tip of the nozzle electrode 7 and the flow of the plasma gas 8. The better the concentration of the plasma arc, which is a high-density energy heat source, the better. That is, the smaller the size of the heat source, the faster the metal melts and the smaller the size of the molten metal pool. In addition, the output current of the plasma arc generation power supply is as shown in Figure 4.
It is a pulsating output that increases and decreases periodically, and as a result, the amount of heat of the plasma arc 11 obtained from this plasma arc generation power source 10 also shows a pulsating value that increases and decreases periodically, similar to the output current.

When the surface of the sliding material 1 is rapidly heated using such a plasma arc 11 and the heating conditions (progressing speed of the plasma arc 11, output waveform of the plasma arc generation power supply, etc.) are appropriately set, the As shown in Figure 1, intermittent recesses 2 and micro-M structure portions 3 are obtained, and a quench-hardened portion 4 surrounding the micro-structure portions 3 is obtained.

However, when a part of the surface of the sliding material 1 is melted and a part or most of the molten metal is removed to form the recess 2, a part of the removed molten metal is removed from the sliding material 1. The protective film 13 is formed to prevent the removed molten metal particles from adhering to the surface of the sliding material 1 as molten metal particles (so-called sputter 12).
It is difficult to completely prevent adhesion of spatter 12. Therefore, in order to remove the spatter 12 attached to the surface of the sliding material 1 and at the same time remove the protective coating 13, dirt, dust, and oxides on the surface of the sliding material 1, the surface of the sliding material 1 is shot blasted. It is processed and cleaned. Through the above surface treatment process, the shape and surface roughness are finished to almost the required quality, and the surface of the sliding material is quenched and hardened, and a large number of minute recesses 2 having smooth curved surfaces are formed on the surface. Ru. Moreover, the surfaces of these recesses 2 have a hard and fine structure of a rapidly solidified structure, and have good compatibility with the lubricant. The dimensions of the recess to be formed are determined by the heat input density of the high-density energy heat source and its dimensions, the moving speed of the heat source, the melting temperature of the material to be treated, the specific heat and thermal conductivity coefficient, the flow characteristics of the molten metal, and the exclusion of the molten metal. It varies greatly depending on the relationship between the flow rate and velocity of plasma gas and shielding gas, and their flow direction. For example, FIGS. 2 and 3 show the microstructure of minute dents and quench-hardened parts on the surface of sliding material 1 that has been surface-treated using plasma arc under appropriate processing conditions.
The dimensions shown in the figure are W1 and W2 from 0.2 to 1.5
m, h, from 0.15 to 0. 5 m, h2 is 0.
01 to 0.1-. Sliding materials processed to these dimensions have sufficient material strength against frictional surface pressure, and have numerous and appropriately arranged minute and smooth curved recesses that have excellent lubricant retention properties. Therefore, it has excellent wear resistance. FIG. 5 shows a method for surface treatment of a sliding member according to a second embodiment of the present invention. In the figure, there is a thin opening hole 1 at the tip of the main body 14 of the hollow cylindrical laser irradiation device.
7, and a branch pipe 14A slightly inclined with respect to the axial direction of the main body 14 is provided in the middle. Main body 14
A condensing lens 16 for condensing a laser beam is provided in the hollow cylinder so that the axis of the main body 14 and the optical axis are parallel to each other.

The surface treatment is performed by a laser beam 15 emitted through the hollow part of the main body 14 of the laser irradiation device, and this laser beam is finely focused by a condensing lens 16 and then passes through an aperture 17 to the sliding material. is radiated onto the surface of 1. The surface of the sliding material 1 is rapidly heated by the projected high-density energy heat source laser beam.
By periodically varying the amount of irradiation heat, the broken line shape,
The surface of the sliding material 1 is locally melted to a minute depth in the form of failure points and discontinuities. Further, an oxidizing gas (for example, air) 18 is supplied to the branch pipe 14A, and the supplied oxidizing gas 18 is blown as a jet onto the molten metal through the opening hole 17 at the tip of the main body 14, The molten metal is transformed into an oxide and some or most of it is blown away. Metal oxides that are rapidly oxidized at high temperatures are porous and brittle, so they hardly adhere to the surface of the sliding material 1, and even if they do, they are easily removed.
Therefore, in the case of this embodiment, almost no molten metal adheres even if a protective film for preventing molten metal from adhering is not formed. Furthermore, if a protective film is formed on the surface of the sliding material 1, no molten metal will adhere, or if it does adhere, it will be removed very easily. In addition, in the surface treatment method of this embodiment, most of the molten metal is removed as oxides, so the minute recesses on the surface of the sliding material 1 are formed in the desired shape, position, and depth with high dimensional accuracy. can do. In addition, in the surface treatment method of the present invention, after finishing the surface of the sliding material 1 to the approximate final shape and surface roughness, a local part of the sliding surface is melted and removed by a minute depth to form a minute recess. Since this is a surface treatment method, in principle the non-melted surface maintains the surface shape and surface roughness before treatment. However, although the surface shape and surface roughness may deteriorate due to the rapid heating and cooling associated with the surface treatment of the present invention, the degree of deterioration is extremely small because there is almost no thermal deformation, and the deteriorated portion can be easily removed by grinding, puffing, lapping, etc. Moreover, if the heating surface is actively cooled by spraying a cooling liquid, the occurrence of the above-mentioned thermal deformation and thermal strain can be greatly reduced.

FIG. 6 shows a third embodiment of the invention. In the figure, a ring-shaped member 22 whose outer peripheral surface is a sliding surface is fitted onto the rotating shaft 19. A bearing 22 is provided in contact with the outer peripheral surface of the ring-shaped member 20. Rotating shafts for pumps used in highly corrosive environments, such as seawater pumps, are often made of highly corrosion-resistant materials such as stainless steel. However, since these corrosion-resistant materials have poor sliding properties, it is necessary to improve their wear resistance. Therefore, a ring-shaped member 2 made of iron-based alloy is attached to the outer periphery of the rotary shaft 19, which has corrosion resistance.
0 are fitted and integrated by means of a shrink or cold fit. Next, the outer peripheral surface of the ring-shaped member 20 is processed into the approximate final shape and surface roughness. Then, by the surface treatment method of the present invention, the ring-shaped member 20
A minute recess 21 is formed in an appropriate shape, for example, a spiral shape, on the outer circumferential surface. Finally, the outer peripheral surface of the ring-shaped member 20 is finished to become a sliding surface. The spiral-shaped recesses 21 formed on the outer peripheral surface of the ring-shaped member 20 are discontinuous in the sliding direction as the rotating shaft 19 rotates. The lubricant is held in the spiral recess 21 and is reliably supplied to the sliding surface, improving the sliding characteristics. Further, according to the bearing structure of this embodiment, the degree of freedom in selecting the material of the shaft is increased, surface treatment is facilitated, and sliding performance is improved. According to the surface treatment method of the present invention, by rapidly melting the surface of the sliding material locally and to a minute depth using a high-density energy heat source, minute depressions effective for improving wear resistance can be created. It is formed. Therefore, the surface treatment of the outer circumferential surface of the ring-shaped member 20 can be performed without affecting the fitting precision of the shrink-fit or cold-shrink portion. Further, if a ring-shaped member 20 made of an iron-based alloy containing 0.2% or more of carbon element is used, the outer circumferential surface of the ring-shaped member is simultaneously quenched and hardened along with the surface treatment.

In the surface treatment method of the present invention, the surface treatment is performed with only a depth of about 0.2 to 2 m of the outer circumferential surface of the ring-shaped member 20 being affected by heat. Therefore, as mentioned above, the rotation axis 1
Although it is possible to perform surface treatment after the ring-shaped member 9 and the ring-shaped member 20 are previously shrink-fitted together, if the ring-shaped member 20 having an appropriate wall thickness is used, the ring-shaped member that has been surface-treated in advance can be treated. 20 may be coupled to the rotating shaft 19 by shrink fit. For example, after nine water-cooled copper rods are fitted inside a ring-shaped member 20 made of carbon steel (for example, 845C) machined to a thickness of 10 m, the ring-shaped member 20 is
The outer circumferential surface of is treated by the surface treatment method of the present invention to form a recess 21 having a minute and smooth curved surface, and at the same time,
It is quenched and hardened to a depth of 0.2 to 0.5 m from the outer peripheral surface. Next, after the water-cooled copper round bar is extracted from the ring-shaped member 20, the ring-shaped member 20 is heated to a shrink-fitting temperature of about 200°C. Next, the ring-shaped member 20 is inserted into a predetermined position of the rotating shaft 19, and the rotating shaft 19 and the ring-shaped member 20 are coupled by shrink fitting. Finally, the surface of the ring-shaped member 20 is subjected to a finishing treatment such as grinding, puffing, or lapping to achieve the dimensions and surface roughness required for a sliding material. The rotating shaft 19 and the ring-shaped member 20 are machined in advance taking into consideration the finishing allowance, but in the method of the present invention, the deformation due to thermal deformation caused by surface treatment and shrink fitting is extremely small. The finishing allowance mentioned above is small. Therefore, the final finishing is simple and easy, and the finishing allowance is small. Furthermore, the object of the present invention is achieved even when the inner surface of the ring-shaped member 20 is subjected to the above-described surface treatment and the ring-shaped member 20 is shrink-fitted and integrated into the inner surface of the bearing 22. This has been achieved, and a bearing structure with excellent wear resistance can be realized. FIG. 7 shows a fourth embodiment of the present invention, and FIG. 8 shows a cross section taken along the line 1--2 in FIG. A large number of minute linear recesses 25 are formed in parallel to the axial direction of the rotary shaft 23 on the sliding surface of the rotary shaft 23 that is in direct contact with the slide bearing 24 used under oil-lubricated conditions.

The axial width b of the recess 25 is slightly smaller than the axial width a of the sliding surface, and each recess 25 is formed as an elongated and independent recess on the sliding surface of the rotating shaft. One way to improve the sliding characteristics of plain bearings is to use lubricating oil26.
It is generally practiced to supply the liquid to the entire surface.

However, when the bearing load is large and the rotational speed is slow, the gap d between the rotating shaft 23 and the bearing 24 becomes too narrow and the lubricating oil film is interrupted, which may cause metal contact between the rotating shaft and the bearing. Once metal contact occurs, the sliding surface seizes due to frictional heat and the friction surface is significantly damaged, resulting in loss of wear resistance. Many are provided parallel to the direction,
Lubricating oil 26 is always held in this recess 25. Even if the rotating shaft 23 and the bearing 24 come into metal contact under friction conditions such as a large bearing load and a slow rotational speed and generate frictional heat, the lubricating oil 26 held in the recess 25 will prevent the metal contact from occurring. This improves the lubrication of metal contact surfaces. If seizure occurs further,
Since the concave portion 25 prevents the enlargement of the seize-damaged portion, locking due to seize is less likely to occur.

On the other hand, when the rotation speed is high, an appropriate oil film surface is formed between the rotating shaft 23 and the bearing 24 due to the wedge film effect.
There is no metal contact between the rotating shaft 23 and the bearing 24, resulting in good wear resistance. Therefore, the minute recess 25 is parallel to the rotation axis.
The burri friction bearing structure has excellent wear resistance under a wide range of burri friction conditions from low speeds to high speeds, even under conditions of large bearing loads. If the depth of the recess provided on the surface of the sliding shaft is sufficiently shallow, for example, about 0.005 to 0.02 mm, the lubricating oil will be retained by the surface tension of the lubricating oil, so it will be independent as described above. It does not have to be a concave part. That is, if the recesses are formed in a spiral or lattice shape on the shaft surface and the recesses are disposed intermittently in the sliding direction, the same effect as the above-mentioned independent recesses can be obtained. 9 and 10 show fifth and sixth embodiments of the present invention. The surface of the sliding material 1 made of SUS304 stainless steel is rapidly melted locally to a minute depth using a high-density energy heat source such as a laser beam, and gas is blown onto this part to melt some of the molten metal or Most of it is blown away, and a small and smooth curved recess 2 is formed.

The surface of the formed recess 2 is covered with a fine structure 3, and a smooth curved surface is formed by solidifying a portion of the molten metal that was not blown away. Next, this sliding material 1
The surface has been shot blasted and is attached to the sliding material surface. Spatter, dirt, dust, and oxides are removed, and minute recesses are formed on the surface of the sliding material, and surface treatment is performed to facilitate adhesion of plating in the subsequent process. Finally, hard chrome plating is applied to the surface of the sliding material 1 to harden the surface of the sliding material and form a plating film 27 having excellent corrosion resistance and wear resistance. The stainless steel sliding member treated in the above process has excellent corrosion resistance and wear resistance, and has minute recesses for retaining lubricant, and has a remarkable effect of improving wear resistance. The surface treatment method of the present invention is also effective for improving the wear resistance of sliding members made of materials such as aluminum, copper, and stainless steel that cannot be hardened by rapid heating and cooling treatments alone, such as stainless steel. It is. The surface treatment method of the present invention is also effective for improving the wear resistance of sliding materials such as materials that cannot be hardened by quenching, such as mild steel, and materials that are subject to high load surface pressure and require a harder structure than hardened by quenching. It is. For example, when applied to mild steel (SPCC material), as shown in FIG. The metal is melted very rapidly, and gas is blown onto this portion to blow off part or most of the molten metal, forming a minute and smooth curved recess 2. The surface of the formed recess 2 is
It becomes a fine resolidified structure after being rapidly cooled, and has good compatibility with substances for improving sliding properties, such as lubricating oil and molybdenum disulfide, and has good retention of these substances. Also,
Carbon elements infiltrate this sliding material from the surface on the sliding surface side.
The hardened portion 28 is formed by being diffused and carburized to a predetermined depth from the surface. Furthermore, after the surface of the sliding material is first carburized, the surface treatment of the present invention is performed to form minute recesses and the carburized portion is quenched and hardened.
Finally, if the surface is nitrided, the surface of the sliding material will have a harder and more wear-resistant surface texture than if it were simply carburized or nitrided, and the sliding material would have better dimensional accuracy. is obtained. Among the surface hardening methods for metal materials, there are methods in which the once hardened surface is softened by heating. However, in the surface treatment method of the present invention, only a localized and minute depth of the surface is rapidly melted by a high-density energy heat source, so the area that is affected by heat is extremely small and limited. Applicable. Furthermore, since the surface treatment method of the present invention rapidly heats the surface, rapidly melts the metal to a very small depth, and further blows off the molten metal with gas or liquid, even if the surface is hard, it is easy to create fine and smooth surfaces. A curved recess is formed.

In addition, after micro recesses are formed on the surface of the sliding material by the surface treatment of the present invention, carburizing treatment, nitriding treatment, oxynitriding treatment, etc.
It is also possible to perform various surface hardening treatments such as hydrochloric oxynitriding treatment.

FIG. 11 shows a seventh embodiment of the invention. A plasma torch 5 that swings in the axial direction of the rotating shaft is attached to a set position of the rotating shaft 23 to be surface-treated, and the rotating shaft 23 is rotated.
The surface of the specimen is rapidly melted locally and to a very small depth by the plasma arc 11. At the same time, high-pressure water 30, which is a cooling liquid, is sprayed from a nozzle 29 onto the molten portion of the rotary shaft 23, blowing away the molten metal, forming a recess 25, and rapidly cooling this portion. If the rotating shaft 23 is made of a material that can be quenched and hardened, for example, cast iron (FCD45), minute recesses will be formed on the surface as a result of the above surface treatment, and at the same time, this portion will be quenched and hardened. be done. In addition, in the method of this example, rapid heating,
Immediately after micro-melting, cooling water is actively sprayed,
Since rapid cooling is performed, the temperature rise of the rotating shaft 23 during processing can be suppressed, and thermal deformation and thermal strain accompanying processing can be extremely reduced. In addition, cast iron (FC
D45) is a material that is susceptible to quench cracking due to rapid stress changes due to thermal strain when rapidly heated and cooled, but according to the method of this example, the heated portion is limited to a localized and minute portion. In addition, since the heated portion is rapidly cooled immediately after heating, even materials that are prone to quench cracking, such as cast iron, can be quenched and hardened without causing quench cracks.

Furthermore, as described above, in the case of a ring-shaped member coupled to the rotating shaft 23 by shrink fitting, the surface treatment method of this embodiment is more effective since thermal deformation is small, and the material selection It increases the degree of freedom of operation and is effective in improving the corrosion resistance and wear resistance of various machines and reducing costs. Although the shape of the recess 25 is shown in a meandering shape in FIG. 11, the implementation of the present invention is not limited to this shape. The recesses 25 can be formed in various shapes depending on the combination of the rotational speed n of the rotating shaft 23 and the swinging speed N of the plasma torch. The shape of the recess in FIG. 11 is n If the shape is formed, it is possible to form concave shapes such as a mountain shape, a wave shape, and a spiral shape.

Next, in order to further clarify the effects of the present invention, surface treatment conditions and wear test results of sliding members according to examples of the present invention will be explained.

845C, a common carbon steel containing 0.4 to 0.5% carbon element, was used as the material to be treated. First, after the surface to be treated is finished to a semi-finished level, the surface to be treated is locally and rapidly melted by a converged plasma arc, and about 0.5 to 0.8 of the molten metal volume is absorbed by the plasma gas. It was removed from the molten pool by the jetting force, and a depression with a depth of about 0.02 to 0.05 mm was formed from the surface of the material to be treated.

Since 845C molten metal has high viscosity and poor fluidity,
Most of the removed molten metal was re-welded to the formed recess and the surface of the sliding material around the recess.

The plasma arc has a wide width of 30 to 50 mm and a width of 0.5 mm.
The recesses are oscillated at a high speed of about 10 times/second, and the interval between each recess (that is, the oscillation pitch) is about 0.5 to 3 m, and the depth of the recess is 0.02 to 0.05 m. A sliding material surface structure with a width of 0.2 to IIIQ+ and a depth of 0.1 to Q,5 am of the quench hardened part was obtained. Furthermore, since the fluidity of the molten metal is poor, the removed molten metal re-welds in and around the recess, and during the solidification process, it condenses irregularly due to surface tension and hardens. When these solidified metal structures are appropriately ground and removed so that the area ratio of the recesses is approximately 0.3 to 0.5, the recesses become mesh-like, with each recess separated and divided. Ta. In other words, in a material such as 845C, which has a high viscosity of molten metal and poor fluidity, it is possible to form appropriately and irregularly divided recesses without changing the amount of human heat due to the influence of surface tension. .

Further, since 845C contains about 0.45% of carbon element, quench hardening occurs due to these rapid heating and rapid cooling treatments. In the above example, 0.1 to 0.5III from the surface
The hardness at a depth of about m increased from Hv600 to Hv800. The wear test conducted was a sliding friction test in which the cylindrical ring and flat plate were immersed in lubricating oil, and the end face of the cylindrical ring was brought into contact with the flat plate to apply load and rotation to the cylindrical ring. This cylindrical ring is made of carbon steel 845C which is quenched and hardened and then ground to a sufficiently smooth finish. Two types of flat plates were used: a conventional product made of carbon steel 345C that was quenched and hardened and then ground to a sufficiently smooth finish, and a product of the present invention that was finished using the surface treatment method described above. The dimensions and properties of the flat plate finished with the surface treatment of the present invention described above are as follows: the depth of the recess is 0.02
mm, recess width 0.3 to 0.5 miz, recess length 1
3, the area ratio of the concave part is 0.3, the depth of the quench-hardened part is 0.3 mm, the hardness of the quench-hardened part} { v 6 0
The hardness of the base material was 0 to 800, the hardness of the base material was 200 to 230 Hv, and the surface roughness of areas other than the recesses was 1.0μ.

Wear tests were conducted using the above test pieces under various friction conditions of loads and sliding speeds, and the results showed that the friction coefficient of the conventional product ranged from 0.02 to 0. O.S. The wear amount of the flat plate surface-treated by this example was 0.04 to 0.08, but when the conventional product was set to 1, the wear amount was significantly reduced to 0.5 to 0.05 for the example product of the present invention. ．． That is, under the same friction conditions, the friction life of the product of the present invention was found to be 2 to 20 times longer than that of the conventional product. The reason why the friction life was improved is that the lubrication performance of the sliding surface was improved as a result of the provision of minute recesses on the sliding surface. In the above explanation, we have discussed the case where laser beams and plasma arcs, which are often used as practical high-density energy heat sources, are used, but it is also possible to use electron beams, light beams, plasma jets, etc. under appropriate heating conditions. Once set, the surface treatment method of the present invention can be implemented. Moreover, although only the case of a rotating shaft and a bearing is illustrated as a sliding part, the present invention is not limited to only a sliding part of this structure. For example, the surface treatment method and sliding material of the present invention can be applied to sliding parts of various structures and types, such as sliding parts between cams and lock arms, thrust bearings, reciprocating pistons, and hydraulic cylinders. It is.

(Effects of the Invention) As described above in detail, according to the sliding material according to the present invention, a large number of minute recesses are provided in at least a portion of the sliding surface of the sliding material, and the surface of the recess is has a smooth curved surface shape, and the recess serves as a holding part for lubricating oil, lubricating grease, lubricating powder, or lubricating solid to improve the wear resistance of sliding materials, and from these four parts as appropriate, A lubricant can be supplied to the sliding surfaces.Especially under friction conditions where lubricating oil is used, the amount of wear is significantly reduced, extending the life of machines using this sliding material and making maintenance easier. In addition, according to the sliding material according to the present invention, the degree of freedom in selecting the rotating shaft material increases, so it is possible to improve wear resistance, corrosion resistance, and reduce the material cost of the rotating shaft material. The surface treatment method of the present invention requires only a small amount of human heat associated with surface treatment, heats locally, and performs rapid heating and cooling, so there is little thermal deformation associated with surface treatment and post-processing is also possible. Since there is almost no need for surface treatment, surface treatment can be carried out easily and inexpensively.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the surface treatment method for sliding materials according to the present invention, FIG. 2 is a cross-sectional view taken along the line u-n in FIG. 1, and FIG. FIG. 4 is a conceptual diagram showing an example of the waveform of the output current of the plasma arc generating power source; FIG. 5 is a cross-sectional view showing a second embodiment of the present invention; 6 is a side view showing the third embodiment of the present invention, FIG. 7 is a side view showing the fourth embodiment of the present invention, and FIG. 8 is a cross-sectional view taken along the line 1-2 in FIG. FIG. 9 is a sectional view showing a fifth embodiment of the invention, FIG. 10 is a sectional view showing a sixth embodiment of the invention, and FIG. 11 is a perspective view showing a seventh embodiment of the invention. This is a diagram. l... Sliding material, 2, 21.25... Recess, 3...
Microstructure part (quenched resolidified structure), 4... Quench hardened part (hardened structure), ... Gas jet (plasma gas), ... Gas jet (shielding gas), 1... High-density energy heat source ( plasma arc), 2.
... Spatter, 13... Protective film, 5... High-density energy heat source (laser beam), 8... Oxidizing gas (air), 9, 23... Rotating shaft, 20... Ring shape Part, 2,
24... Bearing, 30... Cooling liquid (water). Figure 1

Claims (10)

[Claims] 1. The surface of a sliding material made of iron-based alloy is rapidly heated using a concentrated high-density energy heat source, and the surface of the sliding material is locally melted to a minute depth, while at the same time a jet of gas is blown onto the molten metal. A method for surface treatment of a sliding material, characterized in that a minute recess is formed, and a portion surrounding the recess is quenched and hardened by the rapid heating. 2. The surface of the sliding material made of iron-based alloy is rapidly heated using a concentrated high-density energy heat source, and the surface of the sliding material is locally melted to a very small depth. At the same time, a cooling liquid is applied to the molten metal. A method for surface treatment of a sliding material, characterized in that a part or most of the molten metal is removed by spraying to form minute recesses on the surface of the sliding material. 3. The surface of a sliding metal material is rapidly heated using a concentrated high-density energy heat source, and the surface of the sliding material is locally melted to a minute depth, and at the same time, oxidizing gas or A sliding material characterized in that a part or most of the molten metal is oxidized by spraying a liquid, and then the oxide is removed by an appropriate means to form minute recesses on the surface of the sliding material. Surface treatment method for moving materials. 4. A first step of finishing the surface of a sliding material made of an iron-based alloy into a roughly final shape, a second step of forming a protective film to prevent molten metal from adhering to the surface of the sliding material, and a second step of forming a protective film on the surface of the sliding material to prevent adhesion of molten metal to the surface of the sliding material. A third step of rapidly melting the molten metal locally and to a minute depth using a high-density energy heat source and eliminating a part or most of the molten metal, and a protective coating on the surface of the sliding material, the molten metal and A fourth step of removing oxides and finishing the sliding surface;
A method for surface treatment of sliding materials. 5. A minute recess is formed in at least a portion of the sliding surface, the surface of the recess is a curved surface, and the surface of the recess has a fine rapidly cooled and resolidified structure. A sliding material characterized in that a hardened structure is formed so as to surround the resolidified structure. 6. A minute recess with a curved surface is formed in at least a part of the sliding surface, the surface of the recess is curved, and the surface of the recess is fine and rapidly cooled and resolidified. 1. A sliding material characterized by having a structure and having a substance effective for improving sliding performance held in the recesses. 7. A bearing member for a rotating body, in which a ring-shaped member made of an iron alloy with a sliding surface is fitted to the shaft or bearing, and the sliding surface of the ring-shaped member is hard and smooth. A bearing member comprising a surface and a plurality of minute recesses. 8. A sliding surface provided on a part of the rotating shaft has a hard smooth surface and a large number of groove-shaped recesses formed on the smooth surface substantially parallel to the axis of the rotating shaft, and the recesses are A rotating shaft characterized by forming a lubricant holding part. 9. While moving a pulsating high-density energy heat source whose output heat quantity changes periodically over the surface of the iron-based alloy sliding member, the heat source melts the surface locally and only to a minute depth, and at the same time melts the surface. 1. A method for surface treatment of a sliding material, which comprises removing part or most of the metal by appropriate means and forming a large number of minute recesses in the shape of broken lines or discontinuously on the surface. 10. Claims 2, 3, 4, characterized in that the method comprises a step of hardening the surface of the sliding material by a predetermined depth from the surface.
8. The method for surface treatment of a sliding material according to 6, 7 or 8.