JP2008240759A - Thrust bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive thrust needle roller bearing for a swash plate compressor having excellent wear resistance and surface peeling resistance, and a long lifetime. <P>SOLUTION: A thrust needle roller bearing for a swash plate compressor is provided with a raceway disks 12 having a raceway surface on a wall surface of a thickness direction one side. The raceway disks 12 is obtained by carrying out heat treatment of a polished strip steel of surface roughness Rmax≤2 μm obtained by cold rolling of a high carbon steel containing 0.9-1.2 wt.% carbon, 1.2-1.7 wt.% chromium, 0.1-0.5 wt.% manganese and 0.15-0.35 wt.% silicon. The raceway surface is divided into a radial direction inside zone 12a, a radial direction center zone 12b and a radial direction outside zone 12c. A section height of the radial direction center zone 12b is relatively low as compared with those of the radial direction inside zone 12a and the radial direction outside zone 12c, and the maximum height difference is 30 μm or less. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thrust bearing, and more specifically to a thrust bearing used in a swash plate compressor of a car air conditioner.

  Conventionally, as a bearing for supporting a swash plate of a swash plate compressor used in a car air conditioner or the like, for example, described in Japanese Patent Laid-Open No. 2003-65226 (Patent Document 1) or Japanese Patent Laid-Open No. 2004-316930 (Patent Document 2) A thrust needle roller bearing for a swash plate type compressor is used.

  The thrust needle roller bearing rotates at a high speed of about 8000 (r / min), and a thrust load acts on a position (offset) deviated from the bearing rotation axis. Further, the lubricant used in the car air conditioner is a mixture of a refrigerant and refrigerating machine oil and has poor lubricity. Thus, swash plate type thrust needle roller bearings for compressors are used under extremely severe conditions.

  The thrust needle roller bearing having the above configuration is derived from its original structure, and differential slip occurs between the inner diameter side and the outer diameter side of the needle roller even during normal rotation. This slip has an adverse effect on the oil film formation on the rolling contact surface, and causes surface damage on the contact surfaces of the raceway and the needle rollers.

In order to reduce the influence of this differential slip, the roller length of the needle roller may be shortened. However, when the roller length is shortened, the contact surface pressure of the rolling contact surface increases. Due to the increase of the contact surface pressure, a decrease in rolling fatigue life becomes a problem.
JP 2003-65226 A JP 2004-316930 A

  In the above thrust needle roller bearing, since a mixture of refrigerant and refrigeration oil is used as a lubricant, the lubricity of the lubricant is further reduced due to a reduction in the mixing ratio of the refrigeration oil due to a demand for improving the efficiency of the compressor. There is a tendency. Under such lean lubrication, the surface damage of the bearing disc or needle roller due to differential slip tends to increase.

  As recent technical trends, resource saving, energy saving, and downsizing of component structures have further progressed, and usage conditions have become more severe. For this reason, thrust needle roller bearings for car air conditioners are also required to be low in cost, further reduced in wear, and improved in peeling life.

  Accordingly, an object of the present invention is to provide a thrust bearing for a swash plate compressor that is low in cost, excellent in wear resistance, and has a long life.

  The thrust bearing according to the present invention includes a rotational load of a main shaft of a swash plate compressor that reciprocates a piston by rotating a swash plate fixed to the main shaft around the main shaft, and a thrust load generated along with the reciprocating motion of the piston. In order to support this, many are arranged at a position in contact with the swash plate. This thrust bearing includes a washer having a raceway surface on a wall surface on one side in the thickness direction. The washer is composed of 0.9 wt% to 1.2 wt% carbon, 1.2 wt% to 1.7 wt% chromium, 0.1 wt% to 0.5 wt% manganese, and 0.15 wt% to The surface roughness obtained by cold rolling a high carbon steel containing 0.35 wt% silicon is formed by subjecting the steel strip to a heat treatment of Rmax ≦ 2 μm. Further, the raceway surface is divided into a radially inner region, a radially central region, and a radially outer region, and the radial center region has a relatively high sectional height compared to the radially inner region and the radially outer region. The maximum height difference is 30 μm or less.

  By using carbon steel having the above chemical components, the mechanical properties of the washer are improved. Specifically, it is possible to improve hardenability, improve rolling fatigue life and load resistance, reduce friction and wear, improve hardness, and prevent damage to the washer due to press working. In particular, by setting the amount of retained austenite in the surface nitrogen-enriched layer to 10% or less, the retained austenite is decomposed into tempered martensite and fine carbides (particle size of 5 μm or less), and rolling under high load. Fatigue life and load resistance are improved, and friction and wear can be reduced.

  In addition, the steel sheet manufactured through the cold rolling process can obtain the desired dimensions, surface smoothness, and hardness, so the turning process and surface to adjust the dimensions during the manufacturing process of the washer are smooth. The grinding step and the like can be omitted. Thereby, since the manufacturing process of a washer is simplified, the manufacturing cost of a thrust bearing can be reduced. Furthermore, the surface nitrogen-enriched layer obtained by the heat treatment is not removed.

  By using carbon steel having the above chemical components, the mechanical properties of the washer are improved. Specifically, it is possible to improve hardenability, improve rolling fatigue life and load resistance, reduce friction and wear, improve hardness, and prevent damage to the washer due to press working.

  In addition, the steel sheet manufactured through the cold rolling process can obtain the desired dimensions, surface smoothness, and hardness, so the turning process and surface to adjust the dimensions during the manufacturing process of the washer are smooth. The grinding step and the like can be omitted. Thereby, since the manufacturing process of a washer is simplified, the manufacturing cost of a thrust bearing can be reduced. Furthermore, the surface nitrogen-enriched layer obtained by the heat treatment is not removed.

  Furthermore, by making the surface shape of the washer as described above, the lubricity is improved and the wear resistance and seizure resistance due to the reduction of the surface pressure are improved. As a result, it is possible to obtain a thrust bearing that has a long life and can reduce costs. The “race surface” is a concept including both a surface of the rolling bearing that contacts the rolling elements of the washer and a sliding surface of the slide bearing that contacts each other.

  Preferably, the shape in which the radial center region has a relatively low cross-sectional height as compared with the radially inner region and the radially outer region, and the maximum height difference is 30 μm or less is a generatrix shape passing through the center of the washer Are always formed on the same surface. Although the effect of the present invention can be obtained even if the above relationship is established only at a part of the washer, a higher effect can be expected if it is established at all positions in the circumferential direction of the raceway surface.

  As one embodiment, the thrust bearing has a plurality of needle rollers, a retainer that holds the plurality of needle rollers, and a bearing needle that holds the plurality of needle rollers from the thickness direction of the retainer. It is a roller bearing. In addition to the thrust roller bearing having the above-described configuration, the present invention can be applied to a washer of a thrust slide bearing.

  According to the present invention, by producing a washer by using a steel plate obtained by cold rolling carbon steel having a predetermined chemical composition as a starting material, the lubricity of the washer is improved and wear resistance is reduced by reducing the surface pressure. By improving the property and seizure resistance, a long-life and low-cost thrust bearing can be obtained.

  Furthermore, by adopting the above thrust needle roller bearing for a swash plate compressor, a long-life and highly reliable swash plate compressor can be obtained.

  With reference to FIGS. 5-7, the swash plate type compressors 51, 61, 71 which employ | adopted the thrust bearing which concerns on this invention are demonstrated. 5 shows a swash plate compressor 51 of a swash plate type, FIG. 6 shows a swash plate compressor 61 of a double swash plate type, and FIG. 7 shows a swash plate compressor 71 of a variable capacity swash plate type. FIG.

  First, referring to FIG. 5, a swash plate type swash plate compressor 51 mainly includes a casing 52, a main shaft 57, a single-side inclined plate 58, and a piston 59. The swash plate compressor 51 is used, for example, to compress refrigerant vapor of a car air conditioner.

  The casing 22 fixes a head case 53 having a low pressure chamber 55 and a high pressure chamber 56 and a cylinder case 54 having a cylinder 54a in which a piston 59 reciprocates with bolts.

  The low pressure chamber 55 has a suction port (not shown) provided in the head case 53, a suction hole 55a communicating with the cylinder 54a, and a valve (not shown) for preventing the reverse flow of the refrigerant vapor from the suction hole 55a. Then, the refrigerant vapor sucked from the suction port is supplied to the cylinder 54a through the suction hole 55a.

  On the other hand, the high-pressure chamber 56 includes a discharge port (not shown) provided in the head case 53, a discharge port 56a communicating with the cylinder 54a, and a valve 56b that prevents the reverse flow of the refrigerant vapor from the discharge port 56a. Then, the refrigerant vapor inside the cylinder 54a compressed by the piston 59 is discharged to the high pressure chamber 56 through the discharge port 56a.

  The main shaft 57 is rotatably supported with respect to the casing 52 by radial needle roller bearings 57a. A single-sided inclined plate 58 is held inside the cylinder case 54.

  The single-sided inclined plate 58 is fixedly connected to the main shaft 57 while being inclined at a predetermined angle with respect to a plane orthogonal to the rotation axis of the main shaft 57. A piston 59 is connected by a rod on the circumference.

  The piston 59 is connected to the single-sided inclined plate 58 and reciprocates in the axial direction (left-right direction in FIG. 5) in the cylinder 54 a as the main shaft 57 rotates. Further, a compression chamber for compressing the refrigerant vapor (in FIG. 5, the volume of the compression chamber is 0) is formed in a region surrounded by the cylinder 54a and the piston 59.

  The operation of the swash plate compressor 51 having the above configuration will be described.

  First, when the main shaft 57 rotates, the piston 59 attached to the one-side inclined plate 58 reciprocates within the cylinder 54a. When the piston 59 moves in the direction of increasing the volume of the compression chamber (downward in FIG. 5), the valve provided in the suction hole 55a is opened, and the refrigerant vapor passes from the low pressure chamber 55 through the suction hole 55a. Move to. At this time, the valve 56b provided at the discharge port 56a is closed to prevent the refrigerant vapor in the high-pressure chamber 56 from flowing back to the compression chamber.

  Next, when the piston 59 moves in the direction of decreasing the volume of the compression chamber (upward in FIG. 5), the piston 59 compresses the refrigerant vapor in the compression chamber and the valve 56b provided at the discharge port 56a is opened. Then, the compressed refrigerant vapor moves to the high pressure chamber 56 through the discharge port 56a. At this time, the valve provided in the suction hole 55 a is closed to prevent the refrigerant vapor in the compression chamber from flowing back to the low pressure chamber 55.

  In the swash plate compressor 51 having the above-described configuration, the piston 59 reciprocates as the single-sided inclined plate 58 rotates integrally with the main shaft 52. At this time, a thrust load is generated by the rotational movement of the main shaft 57 and the reciprocating movement of the piston 59. Therefore, for the purpose of supporting this thrust load, the thrust needle roller bearing 11 is disposed at a position in contact with the one-side inclined plate 58.

  Further, as another form of the swash plate compressor, a swash plate type swash plate compressor 61 in which a piston 69 is reciprocated by a double-sided inclined plate 68 fixed to a main shaft 67 as shown in FIG. 6, or as shown in FIG. There is a variable capacity swash plate type compressor 71 and the like in which a piston 79 is reciprocated by an inclined plate 78 attached to a main shaft 77 at a variable angle. The basic configuration is the same as that of the swash plate compressor 51 shown in FIG.

  Also in the swash plate compressors 61 and 71, since the inclined plates 68 and 78 receive a thrust load due to the rotational motion of the main shafts 67 and 77 and the reciprocating motion of the pistons 69 and 79, the inclined plates 68 and 78 are thrust needle-shaped. Supported by a roller bearing 11.

  Next, with reference to FIGS. 2-4, the thrust needle roller bearing 11 which concerns on one Embodiment of this invention and the manufacturing method of the washer 12 and 13 of the thrust needle roller bearing 11 are demonstrated. 2 is a view showing the thrust needle roller bearing 11, FIG. 3 is a flowchart showing the main manufacturing process of a polished steel plate as a starting material for the washer 12, 13, and FIG. 4 is a main view of the washer 12, 13. It is a flowchart which shows a manufacturing process.

  First, referring to FIG. 2, the thrust needle roller bearing 11 includes a plurality of needle rollers 14, a cage 15 that holds the plurality of needle rollers 14, and a plurality of needle rollers 14. A pair of washer plates 12 and 13 are sandwiched from the thickness direction.

  The thrust needle roller bearing 11 configured as described above has various advantages such as being able to increase the load capacity and rigidity in a simple manner, while being different between the bearing discs 12 and 13 and the needle roller 14. Dynamic sliding occurs. The needle roller 14 is purely rolled at the center in the length direction, and the relative slip increases linearly as it approaches both ends. In particular, since the needle roller 14 has a long roller length, the difference in peripheral speed at both ends of the needle roller 14 is large, and the slip amount is larger than that of other bearings.

  For this reason, the wear amount of the bearing discs 12 and 13 is increased in a portion where a large differential slip occurs, and surface-origin type separation occurs in the vicinity of the end of the rolling track. In particular, the thrust needle roller bearing 11 has a large number of rollers and a narrow internal space, so that the lubricating oil does not easily reach the raceway surface. As a result, surface-origin type peeling is likely to occur due to insufficient lubrication compared to other bearings.

  In addition, a large thrust load is applied to the bearing discs 12 and 13 employed in the thrust needle roller bearing 11 having the above-described configuration by the rotational motion of the main shafts 57, 67, and 77 and the reciprocating motion of the pistons 58, 68, and 78. . Further, the raceway surface on which the needle rollers 14 roll is required to have predetermined hardness and surface smoothness.

  Therefore, with reference to FIG. 3, a method for manufacturing a steel plate as a starting material for the washer 12 and 13 used in such an environment will be described. First, as materials, 0.9 wt% to 1.2 wt% carbon (C), 1.2 wt% to 1.7 wt% chromium (Cr), and 0.1 wt% to 0.5 wt% manganese (Mn). And a steel slab containing 0.15 wt% to 0.35 wt% of silicon (Si) and other inevitable impurities and iron (Fe) (S11). The oxygen concentration in the steel is 0.0010% or less.

  Carbon (C) is an indispensable element for securing the strength required for the washer disks 12 and 13. Note that 0.9 wt% or more of carbon is required in order to make the hardness of the surfaces and cores of the washer disks 12 and 13 HRC 58 or more. On the other hand, if the carbon content exceeds 1.2 wt%, large carbides are generated on the surfaces of the bearings 12 and 13 to reduce the rolling fatigue life and load resistance, and increase friction and wear. Therefore, the carbon content is desirably in the range of 0.9 wt% to 1.2 wt%. “HRC” indicates Rockwell hardness.

  Chromium (Cr) also improves the hardenability and rolling fatigue life of the washer 12 and 13, secures hardness by carbide, reduces friction and wear, and improves load resistance. It is an indispensable element. In order to obtain a predetermined carbide, 1.2 wt% or more of chromium is required. On the other hand, even if an amount exceeding 1.7 wt% is added, no remarkable effect of addition is observed. Furthermore, if it exceeds 5.0 wt%, large carbides are produced, rolling fatigue life and load resistance are reduced, and friction and wear increase. Therefore, the chromium content is desirably in the range of 1.2 wt% to 1.7 wt%.

  Manganese (Mn) is an element used for deoxidation when manufacturing steel, and is an indispensable element as a starting material for the washer 12 and 13. In order to sufficiently remove oxygen in steel, 0.1 wt% or more of manganese is required. On the other hand, if it exceeds 0.5 wt%, the material becomes brittle, and the washer disks 12 and 13 may be damaged during press working. Therefore, the manganese content is desirably in the range of 0.1 wt% to 0.5 wt%.

  Silicon (Si) is an element unavoidable for steel materials, and the lower limit of the content is 0.15%. On the other hand, if it exceeds 0.35 wt%, the raceway 12 and 13 may be damaged during press working. Therefore, the silicon content is desirably in the range of 0.15 wt% to 0.35 wt%.

  Furthermore, oxygen forms oxides in steel and becomes a starting point for fatigue failure as a non-metallic inclusion, so that the rolling fatigue life and load resistance are reduced, and friction and wear are increased. Therefore, the oxygen concentration in the steel is desirably 0.0010% or less.

  Next, a steel plate is obtained from the above material by hot rolling (S12). By rolling in a heated state, a huge cast structure becomes a fine and high-quality rolled structure. Moreover, since the work hardening of the material can be prevented by rolling in a temperature range equal to or higher than the recrystallization temperature, the thickness can be reduced at a stretch.

  In addition, you may further add the process of annealing the steel plate rolled after the hot rolling process. The crystal grains are refined by annealing, and the crystal orientation is adjusted, so that the surface accuracy and workability are improved.

  Next, pickling is performed for the purpose of rust prevention and removal of an oxide film (scale) attached to the surface of the steel sheet (S13). By removing the oxide film by pickling, production efficiency and product quality in subsequent steps can be improved. The pickling solution includes hydrochloric acid, sulfuric acid, nitric acid and the like, and 5% to 15% dilute hydrochloric acid water is often used at about 40 ° C to 50 ° C.

  Next, a steel plate having a predetermined size is obtained by cold rolling, and mechanical properties such as hardness and surface smoothness required for the washer 12 and 13 are obtained (S14). By rolling at room temperature, a predetermined plate thickness can be obtained accurately and high smoothness can be obtained. Moreover, since the steel plate is work-hardened by rolling in a temperature region below the recrystallization temperature, the hardness of the steel plate is improved.

  Note that the wall surface serving as the raceway surface of the raceways 12 and 13 is required to have a surface roughness of Rmax ≦ 1.6 μm from the viewpoint of smooth rolling of the needle rollers 14. As will be described later, after the shape processing of the bearing discs 12 and 13, only barrel processing that can remove the surface roughness can be performed, and therefore the surface roughness after the cold rolling step is preferably Rmax ≦ 2 μm. Furthermore, from the viewpoint of preventing breakage during press forming, it is desirable that the hardness after the cold rolling step be Hv220 or less. Here, “Rmax” indicates the maximum height, and “Hv” indicates the Vickers hardness.

  Here, the surface roughness, hardness, and plate thickness of the steel sheet obtained by the cold rolling process are the surface roughness of the rolling roll, the bending of the rolling roll, the rolling rate (ratio of the plate thickness before and after rolling), the rolling roll. It is affected by the gap (gap) and the rotation speed. Therefore, in order to obtain a desired surface roughness, hardness, and plate thickness, it is necessary to appropriately set these elements.

  The hot rolling step and the cold rolling step may each have a predetermined thickness in one rolling step, but may be divided into a plurality of times such as rough rolling, intermediate rolling, and finish rolling. It is good also as obtaining the thickness of.

  Next, with reference to FIG. 4, a method for manufacturing the washer 12, 13 according to one embodiment of the present invention will be described. FIG. 4 is a flowchart showing the main manufacturing steps of the washer plates 12 and 13. First, a steel plate (polished steel plate) described with reference to FIG. 3 is adopted as a starting material (S21).

  Next, the steel plate is formed into the shape of the washer 12, 13 by press working (S22). Since the above-mentioned starting materials are already in a desired state such as plate thickness and surface roughness by the cold rolling process, steps such as turning can be omitted. As a result, the manufacturing process can be simplified, and the manufacturing cost of the thrust needle roller bearing 11 can be reduced. In addition, although this press work process is good also as a desired shape by one press work, it is good also as performing a press work in multiple times and obtaining a desired shape. Further, deburring may be performed after press working.

  Next, in order to obtain the mechanical properties required for the washer plates 12, 13, heat treatment including carbonitriding and high-temperature tempering at a tempering temperature of 230 ° C to 280 ° C is performed (S23). By performing the carbonitriding process, a nitrogen-enriched layer is formed on the surface layer of the washer 12, 13. This nitrogen-enriched layer is effective in improving rolling fatigue life and load resistance and reducing friction and wear. The “surface layer” refers to a layer having a thickness of 50 μm from the surface of the washer 12 or 13.

  Here, the nitrogen concentration in the surface nitrogen-enriched layer is preferably in the range of 0.1 wt% to 0.9 wt%. When the nitrogen concentration is less than 0.1 wt%, the above effect is low, and particularly the surface damage life is reduced. On the other hand, when the nitrogen concentration exceeds 0.9 wt%, voids called voids are generated in the material, or the amount of retained austenite increases so much that the hardness is lowered and the life is shortened. The nitrogen concentration can be measured by, for example, EPMA (wavelength dispersion type X-ray microanalyzer).

  Moreover, by performing high temperature tempering, not only the high temperature resistance is improved, but also retained austenite is decomposed into tempered martensite and fine carbides of crystal grains (particle size of 5 μm or less). This is particularly effective for improving rolling fatigue life and load resistance under high load conditions and reducing friction and wear.

  In order to make the retained austenite 10% or less, the tempering temperature needs to be 230 ° C. or more. On the other hand, if the tempering temperature is 280 ° C. or higher, the hardness becomes HRC 60 or lower and the required hardness for the washer 12 or 13 may not be maintained. Therefore, it is desirable to perform high temperature tempering within the range of 230 ° C to 280 ° C. The amount of retained austenite can be measured by comparing the diffraction intensities of martensite α (211) by X-ray diffraction and retained austenite γ (220).

  Finally, the oxide film (scale) generated on the surface of the washer 12, 13 by the heat treatment is removed (S24). As scale removal processing, there are mechanical methods such as barrel treatment and blast cleaning, and chemical methods such as pickling described above.

  Here, the “barrel process” is a process in which the container is rotated or vibrated in a state where the washer 12, 13, compound, and media are put in the container (barrel). According to this method, the scale can be removed, and the effect of improving the deburring and surface roughness of the washer 12 and 13 can be expected. As described above, the surface roughness of the starting material of the washer 12, 13 is already Rmax ≦ 2 μm after the cold rolling process, so it is necessary for the washer 12, 13 without providing an independent grinding process. A surface roughness Rmax ≦ 1.6 μm can be obtained.

  Further, FIG. 1 shows a radial bus bar shape passing through the center of the washer 12 of the washer 12 manufactured in the above process. 1 is divided into a radially inner region 12a, a radially central region 12b, and a radially outer region 12c. And the radial direction center area | region 12b has a relatively low cross-sectional height compared with the radial direction inner side area | region 12a and the radial direction outer side area | region 12c, The maximum height difference is set to 30 micrometers or less. FIG. 1 is an enlarged view of 500 times in the vertical direction and 5 times in the horizontal direction.

  Thus, by making the cross-sectional height of the radial center region 12b of the washer 12 lower than other portions, a uniform oil film can be formed without hindering the flow of the lubricating oil. As a result, the thrust needle roller bearing 11 excellent in lubricity can be obtained.

  In addition, when the raceway surface is made to be a completely flat surface by grinding as in a washer manufactured by a conventional manufacturing process, there is a possibility that edge stress may be generated at the contact portion due to an attachment error or the like. This is particularly noticeable at the inner and outer edges of the washer.

  On the other hand, when a load is applied to the thrust needle roller bearing 11 having the surface of the washer 12 as shown in FIG. 1, the raceway surface of the washer 12 is elastically deformed, and the radially inner region 12a and the radially outer region. The difference in maximum height from 12c is reduced to about several μm (1 μm to 9 μm). As a result, it is possible to reduce the local contact surface pressure, in particular, the contact surface pressure at the highest position (in FIG. 1, “the radially inner region 12a”).

  Furthermore, the washer manufactured by the conventional manufacturing process has a non-uniform surface shape such as swell caused by heat treatment. This may promote local contact and obstruct the flow of the lubricating oil. However, in the washer 12 manufactured by the manufacturing process according to the embodiment of the present invention as shown in FIGS. 3 and 4, the surface shape can be corrected to a uniform state by the tempering process (S23). .

  At least the wall surface on one side in the thickness direction of the washer 12, that is, the raceway surface in contact with the needle rollers 14 (in the case of a thrust slide bearing, “sliding surface in contact with the other washer”) is the above surface shape. Then, the effect of the present invention can be obtained. Further, since the surface of the washer 13 is the same, the description thereof is omitted.

  According to this invention, various mechanical properties of the washer 12 and 13 are improved by using the carbon steel having the above chemical components. As a result, it is possible to obtain bearing discs 12 and 13 with improved rolling fatigue life and load resistance and reduced friction and wear.

  Further, by including a cold rolling step in the manufacturing process of the starting material (step shown in FIG. 3), the plate thickness, hardness, surface roughness and the like necessary for the washer 12 and 13 can be obtained. If it does so, in the manufacturing process (process shown in FIG. 4) of the washer machines 12 and 13, it becomes possible to abbreviate | omit the process of turning or grinding. As a result, the manufacturing process of the washer 12 and 13 is simplified, and the manufacturing cost of the washer 12 and 13 can be reduced.

  Furthermore, by omitting the grinding process after the heat treatment, the nitrogen-enriched layer formed on the surface layer of the washer 12, 13 is not removed. As a result, it is possible to obtain the bearings 12 and 13 with improved rolling fatigue life and load resistance and reduced friction and wear.

  In the above-described embodiment, the method of manufacturing the bearing discs 12 and 13 of the thrust needle roller bearing 11 has been described. However, the present invention is not limited to this, and the present invention is also applicable to the manufacture of other thrust bearings. Can do. For example, a thrust rolling bearing in which the rolling element is a cylindrical roller or a ball may be used, or a thrust sliding bearing having no rolling element may be used. A thrust bearing according to another embodiment of the present invention will be described with reference to FIG. The upper stage is a perspective view, and the lower stage is a side sectional view.

  First, referring to FIG. 8, a thrust slide bearing 21 according to another embodiment of the present invention includes two bearing discs 22 and 23. The track discs 22 and 23 are disc-shaped members having holes 22a and 23a in the center, respectively, and are overlapped so that the sliding surfaces 22b and 23b come into contact with each other.

  The thrust slide bearing 21 fixes, for example, the washer 22 to a rotating shaft (not shown) and the washer 23 to a housing (not shown). Since the washer 22 rotates while sliding on the washer 23, the rotating shaft can be rotatably supported. In addition, the track disc 23 includes a case where it is fixed to another rotating shaft that rotates relative to the rotating shaft.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The present invention is advantageously used for manufacturing a thrust bearing washer for a swash plate compressor.

It is an enlarged view of a bearing disc. It is a figure which shows the thrust needle roller bearing which concerns on one Embodiment of this invention. It is a flowchart which shows the main processes which manufacture a washer. It is a flowchart which shows the main processes which manufacture a washer from a steel plate. It is a figure which shows the swash plate type swash plate type compressor. It is a figure which shows the swash plate type swash plate type compressor. It is a figure which shows a variable capacity swash plate type swash plate type compressor. It is a figure which shows the thrust bearing which concerns on other embodiment of this invention.

Explanation of symbols

  11 Thrust Needle Roller Bearing, 21 Thrust Sliding Bearing, 12, 13, 22, 23 Raceway, 12a Radial Inner Region, 12b Radial Central Region, 12c Radial Outer Region, 22a, 23a Hole, 22b, 23b Sliding Surface, 14 needle rollers, 15 cage, 51, 61, 71 swash plate compressor, 52 casing, 53 head case, 54 cylinder case, 54a cylinder, 55 low pressure chamber, 55a suction hole, 56 high pressure chamber, 56a discharge port, 56b Valve, 57, 67, 77 Main shaft, 57a Radial needle roller bearing, 58, 68, 78 Swash plate, 58, 68, 78 Piston.

Claims (3)

To support the rotational movement of the main shaft of the swash plate compressor that reciprocates the piston and the thrust load generated by the reciprocating movement of the piston by rotating a swash plate fixed to the main shaft around the main shaft. A thrust bearing arranged,
The thrust bearing comprises a washer having a raceway surface on the wall surface on one side in the thickness direction,
The washer includes 0.9 wt% to 1.2 wt% carbon, 1.2 wt% to 1.7 wt% chromium, 0.1 wt% to 0.5 wt% manganese, and 0.15 wt% to 0. A surface roughness obtained by cold rolling a high carbon steel containing .35 wt% silicon is formed by subjecting the steel strip to a heat treatment of Rmax ≦ 2 μm,
The raceway surface is divided into a radially inner region, a radially central region and a radially outer region,
The thrust bearing, wherein the radial central region has a relatively low cross-sectional height compared to the radial inner region and the radial outer region, and a maximum height difference thereof is 30 μm or less.   The radial center region has a relatively low cross-sectional height as compared with the radially inner region and the radially outer region, and the shape having a maximum height difference of 30 μm or less is a generatrix shape passing through the center of the washer The thrust bearing according to claim 1, wherein the thrust bearing is always formed on the same surface. The thrust bearing is
A plurality of needle rollers;
A cage for holding the plurality of needle rollers;
The thrust bearing according to claim 1 or 2, which is a thrust needle roller bearing having the raceway for sandwiching the plurality of needle rollers from the thickness direction of the cage.

Images