JP2007270932A - Thrust bearing mechanism, raceway ring therefor, and method for manufacturing intermediate ring - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thrust bearing mechanism provided with quality applicable under a lean lubrication condition and a high load condition, and capable of being manufactured at low cost. <P>SOLUTION: A plurality of first rollers 12 are arranged between an intermediate ring 11 and a first raceway ring 9 fixed on a first member 3 via a first retainer 13. A plurality of second rollers 14 are arranged between the intermediate ring 11 and a second raceway ring 10 fixed on a second member 4 via a second retainer 14. A rolling axis center of the first rollers 12 and a rolling axis center of the second rollers 14 are arranged to cross at right angles. In this thrust bearing mechanism 8 high frequency heat treatment is applied on at least one of the ring bodies of the raceway rings 9, 10 and the intermediate ring 11, and area closed by old austenite grain boundary is 10% or less of whole visual field. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thrust receiving mechanism, and more particularly to a thrust receiving mechanism that supports a thrust load between two members that perform eccentric rotational motion between each other, such as a turning scroll member and a stationary scroll member in a scroll compressor.

  Scroll compressors are often used in heat pump hot water heaters and the like. For such a scroll compressor, a thrust receiving mechanism as disclosed in Patent Documents 1 to 3 is used. This type of thrust receiving mechanism is a thrust receiving mechanism that supports the thrust load by interposing between the first member and the second member that perform eccentric rotational movement between each other, and is fixed to the first member. The first race ring, the second race ring fixed to the second member, the intermediate ring disposed between the first race ring and the second race ring, and the first race ring and the middle A plurality of first rollers disposed between the wheels, a first retainer having a plurality of pockets for holding the first rollers such that their rolling axes are parallel to each other, and a second A plurality of second rollers disposed between the bearing ring and the intermediate ring, and a second cage having a plurality of pockets for holding the second rollers such that the rolling axes are parallel to each other; And a thrust receiving mechanism configured such that the rolling axis of the first roller and the rolling axis of the second roller are orthogonal to each other. It can be listed as an example.

As an example of the manufacturing process of the raceway ring or the intermediate ring, as shown in FIG. 6B, after forming a steel plate, it is heat-treated for surface hardening and finished by tumbling. For example, JIS standard SCM415 or SUJ2 is used for the steel plate. As the heat treatment, in the case of steel with a low carbon content such as SCM415, carburizing heat treatment or carbonitriding heat treatment is adopted, and after tempering, press tempering is performed to correct warpage and waviness. In the case of steel with a high carbon content such as SUJ2, bright heat treatment is employed instead of carburizing heat treatment. These carburizing heat treatment, carbonitriding heat treatment or bright heat treatment and tempering are performed in a continuous furnace.
JP 2002-242857 A JP 2002-242939 A JP 2002-242940 A

2. Description of the Related Art In recent years, along with higher functionality and cost reduction of heat pump water heaters and the like, longer life, lower cost, and higher quality of a thrust receiving mechanism used in a scroll compressor are required.
A thrust receiving mechanism used in a scroll compressor or the like that employs natural refrigerant (CO2) is used under lean lubrication and high load. Because it is used under severe conditions such as dilute lubrication and high load, it has an effect of suppressing early breakage due to surface damage such as wear and surface-induced peeling, and also due to normal load-dependent rolling fatigue There is a need for a long-life thrust receiving mechanism that has an effect of suppressing internal origin type peeling.

  More specifically, the lubricating oil used in the thrust receiving mechanism of the heat pump type hot water heater has a low viscosity and further reduces the amount of oil to improve the cooling capacity of the scroll compressor. And since natural refrigerant (CO2) is adopted in consideration of the influence on global warming, the pressure inside the compressor is increased, and the thrust receiving mechanism is used under further lean lubrication. For these reasons, an oil film breakage may occur between the roller and the race or intermediate ring, resulting in metal contact. For this reason, the contact portion generates heat, and surface damage such as wear and surface-origin peeling tends to occur.

  In addition, as a use condition of the bearing, there is a tendency to increase the load, and internal origin type separation due to normal load-dependent rolling fatigue also occurs. Under such circumstances, customer requests are effective for early breakage due to surface damage such as wear and surface-induced debonding, and also for internal-origin delamination due to normal load-dependent rolling fatigue. There is a need for a long-life thrust receiving mechanism that is effective.

  The bearing ring or intermediate ring of the thrust receiving mechanism heat-treated by conventional carburizing heat treatment, carbonitriding heat treatment, bright heat treatment, etc., has a surface hardness of HV653 or more, but the inner part when steel with low carbon content such as SCM415 is used. The hardness is about HV400, the internal hardness is insufficient, and it is not sufficient for the internal origin type peeling due to the usual load-dependent rolling fatigue. In addition, when steel with a high carbon content such as SUJ2 is used and bright heat treatment or carbonitriding heat treatment is performed, both surface hardness and internal hardness become HV653 or more, but atmospheric heat treatment such as carburizing heat treatment, carbonitriding heat treatment, bright heat treatment, etc. Since the applied ring has a longer heating time during the heat treatment, the generation of surface austenite grain boundaries on the surface proceeds, and the grain boundaries become distinct grain. Since the grain boundaries of the grains are remarkably different in hardness from the surrounding steel structure, there is a risk that they may become the starting point of wear and cracks, and resistance to the progress of wear and cracks is small. Therefore, when the grain boundary is formed as described above, the contact portion generates heat due to the oil film breakage (metal contact) between the roller and the raceway ring or the intermediate ring under lean lubrication, and wear and surface cracks occur. There is.

  Further, as one of the factors that deteriorate the function of the thrust receiving mechanism as described above, there is warp / swell of the thrust receiving raceway ring or the intermediate ring. In the thrust receiving mechanism, if the raceway or intermediate ring is greatly warped or swelled, the rolling surface of the roller, which is a rolling element, is not flat, and a single contact occurs between the roller and the raceway or intermediate ring. When this piece contact occurs, the oil film is cut and metal contact occurs, the contact portion generates heat, and surface damage such as wear and surface-origin peeling tends to occur. Further, the contact surface pressure locally increases, and internal origin type peeling is likely to occur. Furthermore, if the raceway or intermediate wheel is greatly warped or swelled, noise, vibration, etc. will increase. In order to suppress this warpage and waviness, it is necessary to add machining (cutting, etc.) and a process for correcting deformation (warping and waviness), which also causes high production costs. .

  Furthermore, in the case of conventional atmospheric heat treatment such as carburizing heat treatment and bright heat treatment, the heat treatment process section cannot be arranged in the production line of the thrust receiving mechanism, and it is difficult to improve the productivity and reduce the cost by improving the productivity. Since the heat treatment process cannot be inlined, it is difficult to control the quality of each track or intermediate wheel, which hinders the achievement of high quality.

  The object of the present invention is that, even when used under dilute lubrication and high load, early breakage due to surface damage such as wear and surface-origin separation is unlikely to occur, and internal origin due to normal load-dependent rolling fatigue Mold release is unlikely to occur, and it is possible to realize a long service life. Further, it is possible to reduce the noise by reducing the warpage and undulation of the race ring or intermediate ring, and to improve the productivity and reduce the cost by simplifying the production facility. Another object is to provide a thrust receiving mechanism that can realize high quality by facilitating individual quality control.

The thrust receiving mechanism according to the present invention is a thrust receiving mechanism that supports the thrust load by interposing between the first member and the second member that perform eccentric rotational movement between each other, and is fixed to the first member. The first race ring, the second race ring fixed to the second member, the intermediate ring disposed between the first race ring and the second race ring, and the first race ring and the middle A plurality of first rollers disposed between the wheels, a first retainer having a plurality of pockets for holding the first rollers such that their rolling axes are parallel to each other, and a second A plurality of second rollers disposed between the bearing ring and the intermediate ring, and a second cage having a plurality of pockets for holding the second rollers such that the rolling axes are parallel to each other; The rolling axis of the first roller and the rolling axis of the second roller are orthogonal to each other, and from the first member to the first track ring and A first guide pin extending through the first cage to the intermediate wheel, and a first guide pin extending from the second member through the second race and the second cage to the intermediate wheel. A second guide pin having two guide pins, the first guide pin being movable in a direction perpendicular to the rolling axis of the first roller within a regulation range of the first cage and the intermediate wheel. In a thrust receiving mechanism, characterized in that, in a direction perpendicular to the rolling axis of the second roller, it is movable within the restricted range of the second cage and the intermediate wheel,
At least one of the first and second race rings and the intermediate ring, each of which is a ring body, is hardened and hardened by induction heat treatment and tempered. The cross section perpendicular to the surface is mirror-polished, and the mirror-polished surface is corroded by immersion in a corrosive solution obtained by adding a surfactant to a saturated aqueous picric acid solution, and the central portion of the cross section is observed at a magnification of 400 times using an optical microscope. In this case, the region closed by the prior austenite grain boundary is 10% or less of the entire visual field. It is preferable that the area closed by the crystal grain boundary is 10% or less of the entire visual field in both the surface layer and the inside of the ring body.

According to this configuration, since the heat treatment of the ring body is a high-frequency heat treatment, the temperature raising time and the heating time can be shortened as compared with a ring body subjected to atmospheric heat treatment such as carburizing heat treatment, carbonitriding heat treatment, and bright heat treatment. Therefore, the austenite grain boundary before cooling is not completely formed, and the crystal grain boundary is not clearly formed. The area closed by the prior austenite grain boundary is 10% or less of the entire visual field. Since the crystal grain boundaries are not clearly formed in this way, the resistance to wear, crack generation, and propagation becomes very large. Furthermore, it is possible to extend the life against cracks caused by internal origin separation. For these reasons, even when used under dilute lubrication or under heavy loads, premature failure due to surface damage such as wear or surface-initiated delamination is unlikely to occur, and internal origin-type delamination due to normal load-dependent rolling fatigue It is also difficult to produce a long service life.
In addition, because it uses high-frequency heat treatment and is heated using clean electrical energy, it is easy to inline the heat treatment process section with good operating efficiency and helps improve productivity, so further cost reduction is possible. is there. In other words, the in-line heat treatment process using high-frequency heat treatment can shorten the product manufacturing cycle time, eliminates the need for in-process inventory, simplifies the equipment, and realizes cost reduction. Further, by in-lining the heat treatment process, quality control for each individual ring body, that is, so-called piece-by-piece quality control can be performed, and high quality can be realized.

In this invention, the at least one of the first and second race rings and the intermediate ring is used without performing turning or grinding after the tempering, and the grain boundary of the surface layer portion. The thickness of the oxide layer may be 1 μm or less.
By using high-frequency heat treatment, the temperature rise time and heating time can be shortened compared to rings subjected to atmospheric heat treatment such as carburizing heat treatment, carbonitriding heat treatment, and bright heat treatment. The thickness of the surface grain boundary oxide layer is 1 μm or less, which is equivalent to hardly occurring. Therefore, generation | occurrence | production of abrasion and a surface crack can be suppressed. In the case of atmospheric heat treatment, the grain boundary oxide layer on the surface is generated about 2 to 10 μm, although it varies depending on the heat treatment. If there is a cutting process such as a turning process or a grinding process after the heat treatment, the grain boundary oxide layer is removed by performing a cutting process such as turning or grinding on the surface of the ring body. If there is no process, the grain boundary oxide layer will remain. However, according to this configuration, since there is almost no generation of a grain boundary oxide layer, there is a concern that the grain boundary oxide layer may remain even without a cutting process such as a turning process or a grinding process after the heat treatment. There is no.

  In this invention, it is assumed that the at least one of the first and second race rings and the intermediate ring is used without performing turning or grinding after the tempering. Taken from a group of rings with an average value obtained by adding 3 times the standard deviation of warpage / waviness to an average value when measuring the warpage / waviness of a ring extracted randomly from the group It is also good. Such warp / waviness values are extremely small compared to the conventional one. Therefore, as in the past, due to contact between the roller and the ring body, the oil film is cut and metal contact occurs, the contact part generates heat, and surface damage such as wear or surface-origin peeling occurs locally. In addition, the contact surface pressure becomes high and internal origin type peeling does not occur. Furthermore, since the warping and undulation of the ring body is large, noise and vibration are not increased when the bearing is used, and high accuracy and high functionality (long life, low noise) can be realized.

  In this invention, it is assumed that the at least one of the first and second race rings and the intermediate ring is used without performing turning or grinding after the tempering. When the warpage / waviness of a ring extracted at random from the group was measured, the probability that a ring with a warp / waviness of 40 μm or more was detected was taken from a group of the ring bodies of 0.1% or less. It is good as a thing. As described above, since the probability that a ring body having a warp / waviness of 40 μm or more is detected is as low as 0.1% or less, the above-described high accuracy and high functionality (long life, low noise) can be realized more reliably. .

In the present invention, the surface hardness and the internal hardness of the raceway ring and the intermediate ring may be HV653 or higher in terms of Vickers hardness. The hardness of the bearing ring and the intermediate ring is one of the most important factors for functioning as a thrust receiving mechanism. In the thrust receiving mechanism, it is desirable that the surface hardness of the raceway surface and the intermediate wheel rolling surface is HV653 or more, and if the surface hardness is less than HV653, the rolling fatigue life is reduced. By setting the surface hardness to HV653 or more, it is possible to avoid a decrease in rolling fatigue life. Furthermore, not only the surface but also the internal hardness of the bearing ring and the intermediate ring is set to HV653 or more, so that compared to the bearing ring and the intermediate ring whose surface is only HV653 or more, plastic deformation is less likely to occur in the bearing ring and the intermediate ring. The rolling fatigue life is further improved.
Here, the surface hardness refers to the hardness of a portion (that is, a rolling surface) in contact with the roller in the race and intermediate rings. The internal hardness refers to the hardness of the central portion of the cross section perpendicular to the surface in contact with the rollers in the race and intermediate rings.

  Moreover, in this invention, it is good also considering the material of the said bearing ring and an intermediate | middle ring as steel containing 0.4 mass% or more of carbon. If the steel contains 0.4% by mass or more of carbon, a hardness of HV653 or more can be easily obtained.

  Furthermore, in this invention, the raceway ring and the intermediate ring may be formed by pressing a steel plate. By using a steel plate that has been press-worked, it is possible to obtain a low-cost track ring and intermediate ring as compared to using a member formed by a method such as turning.

  In the thrust receiving mechanism according to the present invention, the raceway ring and the intermediate ring may be used in a CO2 refrigerant and PAG oil (polyalkylene glycol) environment. In a compressor or the like that employs a natural refrigerant, the pressure inside the compressor is increased, and the compressor is used under lean lubrication mixed with PAG oil or the like in order to improve the cooling capacity. However, the thrust receiving mechanism of the present invention is such that at least one of the raceway ring and the intermediate ring is heat-cured by induction hardening, and the region closed by the prior austenite grain boundary is viewed. By setting the thickness to 10% or less of the total, and further the thickness of the surface grain boundary oxide layer to 1 μm or less, wear, surface and internal origin type peeling hardly occur, and a long life can be obtained. In the case of a compressor used in an oil environment, the above-mentioned effect of extending the life is more effectively exhibited.

The method of manufacturing the bearing ring or intermediate ring of the thrust receiving mechanism according to the present invention includes a pressing process in which a material is subjected to plastic processing to form a predetermined shape, and the workpiece formed in the pressing process is held so as not to be deformed. A quenching step of performing induction hardening in a state.
In the method of manufacturing the raceway ring or the intermediate ring of the thrust receiving mechanism according to the present invention, the method may further include a tempering step of performing induction tempering while maintaining a state where the workpiece is held in the quenching step.
According to this manufacturing method, it is possible to reduce warpage and undulation of the race ring or the intermediate ring of the thrust receiving mechanism.

  The thrust receiving mechanism of the present invention is less susceptible to premature breakage due to surface damage such as wear and surface-origin peeling even when used under lean lubrication and high load. Starting-type peeling is unlikely to occur and a long life can be realized. Moreover, the noise accompanying the operation is reduced. Furthermore, the heat treatment process can be inlined, improving productivity, reducing costs by simplifying production facilities, and improving quality by facilitating quality control of individual track rings and intermediate wheels.

An embodiment of the present invention will be described with reference to FIGS. 1 is a cross-sectional view taken along the line A to F in FIG. The thrust receiving mechanism 8 is a mechanism that is interposed between the first member 3 and the second member 4 that perform eccentric rotational movement between each other and supports a thrust load. In this example, the second member 4 is a member on the fixed side, the first member 3 is a member on the eccentric rotation side, and the center C1 of the first member 3 is relative to the center C2 of the second member 4. Thus, the eccentric rotational motion is performed in the state of being eccentric by the eccentric amount e.
The thrust receiving mechanism 8 includes a first race ring 9 fixed to the first member 3, a second race ring 10 fixed to the second member 4, the first race ring 9 and the second race ring 9. Rolling an intermediate ring 11 disposed between the first and second race rings 10, a plurality of first rollers 12 disposed between the first race ring 9 and the intermediate ring 11, and the first rollers 12. A first retainer 13 having a plurality of pockets 13a for holding the shafts in parallel with each other, and a plurality of second rollers disposed between the second race ring 10 and the intermediate ring 11. 14 and a second cage 15 having a plurality of pockets 15a for holding the second rollers 14 so that their rolling axes are parallel to each other. These are laminated vertically so that the rolling axis of the first rollers 12 and the rolling axis of the second rollers 14 are orthogonal to each other.

  The first track ring 9 is in contact with the lower surface of the first member 3, and is positioned and stopped by two guide pins 16, 16 implanted in the first member 3. The second race 10 is in contact with the upper surface of the second member 4 and is positioned and stopped by two guide pins 17, 17 implanted in the second member 4. The first raceway ring 9 and the second raceway ring 10 are formed, for example, by pressing a steel plate into a ring shape having the same shape and dimensions, and two pin holes at each radially opposed position. 9a, 9a and 10a, 10a are provided. The pin holes 9a, 9a and 10a, 10a have substantially the same diameter as the guide pins 16, 16, 17 and 17, and each of the two guide pins 16, 16 and 17, 17 has a first raceway ring. 9 and the second race ring 10 are located in a radially opposing relationship, and their radial directions are orthogonal to each other, and are inserted into the pin holes 9a, 9a and 10a, 10a.

  Further, the intermediate wheel 11 is also formed by pressing a steel plate into a ring shape, and is provided with four pin holes 11a at equal intervals in the circumferential direction. Each of these pin holes 11a is a long hole extending in the radial direction of the intermediate ring 11, and the width thereof is slightly larger than the diameter of the guide pins 16, 16 and 17, 17, and the guide pins 16, The front side portions 16, 17, and 17 are inserted into these pin holes 11 a... So that they can slide relative to each other along the longitudinal direction.

  The guides of the first cage 13 and the second cage 15 are roller guides. The first retainer 13 and the second retainer 15 have a ring shape having the same shape and dimensions as the race rings 9 and 10 and the intermediate ring, and are made of a synthetic resin molding. Each retainer 13, 15 has a plurality of pockets 13 a, 15 a,... Arranged in the circumferential direction, and cylindrical rollers 12, 14,. . The respective pockets 13a ... and 15a ... in the cages 13 and 15 are formed in parallel with each other, so that the rolling axes of the rollers 12 ... and 14 ... held in the pockets 13a ... and 15a ... are parallel. Each retainer 13 and 15 is provided with a pair of pin holes 13b and 13b and 15a and 15a at positions facing each other in the radial direction. These pin holes 13b, 13b and 15b, 15b are elongated holes extending in the radial direction of the cages 13 and 15, and the longitudinal axes of the pin holes 13b, 13b and 15b, 15b are orthogonal to each other. The width dimensions of the pin holes 13b, 13b and 15b, 15b are set to be slightly larger than the diameters of the guide pins 16, 16, 17 and 17, and the guide pins 16, 16 and 17, 17 are respectively provided along the longitudinal direction thereof. It is slidably inserted.

  As shown in FIG. 4, the diameters of the rollers 12 and 14 are slightly larger than the thicknesses of the cages 13 and 15, and the rollers 12 and 14 are disposed on the inner sides of the pockets 13 a and 15 a. Inward projections 13c and 15c are formed so as to be held at the center in the direction. The rollers 12 and 14 are held in the pockets 13a and 15a so as not to fall off by being inserted with elastic deformation of the protrusions 13c and 15c. When the rollers 12 and 14 are held at the central portions of the cages 13 and 15 in the thickness direction, a part of the rollers 12 and 14 protrudes from both upper and lower surfaces of the cages 13 and 15, and the projections hold the bearing rings 9 and 14. A certain clearance is secured between the cage 13, between the cage 13 and the intermediate ring 11, between the intermediate ring 11 and the cage 15, and between the cage 15 and the raceway ring 10.

FIG. 5 is a longitudinal sectional view of a scroll compressor provided with the thrust receiving mechanism 8. Spiral partition walls 5 and 6 are respectively provided on the orbiting scroll member 3 and the fixed scroll member 4A disposed opposite thereto, and the compression chamber 7 formed between the both partition walls 5 and 6 is disposed on the orbiting scroll member 3. The fluid in the compression chamber is compressed by changing the volume along with the eccentric rotation. A natural refrigerant (for example, CO2) is used as the fluid.
A thrust receiving mechanism 8 according to the embodiment of FIGS. 1 to 4 is interposed between the orbiting scroll member 3 and the second member 4 which is a fixed frame fixed integrally to the fixed scroll member 4A. Yes. The orbiting scroll member 3 is the first member.

  The axis C1 of the orbiting scroll member 3 is eccentric by a predetermined eccentricity (revolution radius) e with respect to the axis C2 of the output shaft. When the drive motor 1 is operated, the orbiting scroll member 3 is eccentric. It rotates eccentrically with a revolution radius equal to e. The longitudinal lengths of the pin holes 11a, 13b, and 15b provided in the intermediate ring 11, the first and second cages 13 and 15 are such that the guide pins 16 and 17 are in the longitudinal direction of the pin holes 11a, 13b, and 15b. The distance that can move from one end to the other end is set to be equal to the amount of eccentricity e. Therefore, the rolling axis of the first roller 12 and the rolling axis of the second roller 14 are orthogonal to each other, and the guide pins 16, 17 are in the longitudinal direction of the pin holes 11a, 13b, 15b. When the drive motor 1 is operated according to the relationship between the distance from one end to the other end and the eccentricity e, the rollers 12 and 14 move between the raceway groove 9 and the intermediate ring 11 and between the raceway ring 10 and the intermediate ring 11. , And an eccentric rotation with a revolution radius equal to the eccentric amount e of the orbiting scroll member 3 is performed.

  Thereby, the eccentric rotational motion of the second member 4 which is the fixed frame of the orbiting scroll member 3 is restricted. At the time of the eccentric rotation, the orbiting scroll member 3 is subjected to a force for rotating the orbiting scroll member 3, and a thrust load accompanying a compression operation of the fluid (refrigerant) is applied. The thrust receiving mechanism 8 functions to prevent rotation of the orbiting scroll member 3 and to support a thrust load by the rolling of the rollers 12 and 14 accompanying the eccentric rotation of the orbiting scroll member 3. Then, by changing the volume of the compression chamber 7 formed between the spiral partition walls 5 and 6 provided in the orbiting scroll member 3 and the fixed scroll member 4A with the eccentric rotation of the orbiting scroll member 3, The fluid in the compression chamber (PAG oil is mixed with natural refrigerant such as CO2) is compressed.

  When applied to a thrust receiving mechanism of a scroll compressor using CO2 as a refrigerant, it is lubricated with a fluid in which CO2 and PAG oil are mixed. However, this fluid easily absorbs moisture. The material of 15 is required to have chemical resistance such that hydrolysis does not occur.

  FIG. 6A shows an example of the manufacturing process of the race rings 9 and 10 and the intermediate ring 11 of the thrust receiving mechanism 8. The material of the steel plate employed for the races 9, 10 and the intermediate ring 11 contains 0.4 mass% or more of carbon. For example, S40C to S55C (carbon steel for machine structure), SCM440 to SCM445 (machine Alloy steel for structure), SMN443 (manganese steel for machine structure), SK5 (carbon tool steel), SUJ2, SAE1070, etc. are used. These steel plates are processed into a predetermined shape as described above by press working. In a state where this is constrained, induction hardening is performed as induction heat treatment, and induction tempering is subsequently performed. It is desirable to maintain the constrained state during the induction tempering.

In this case, the heating time in the induction hardening process is extremely short as compared to the atmospheric heat treatment such as carburizing heat treatment, carbonitriding heat treatment, or bright heat treatment, which is a general quench hardening treatment, so the austenite grain boundaries before cooling Is not completely formed. Therefore, the region closed by the prior austenite grain boundary can be made 10% or less of the entire visual field.
Further, since the raceway ring and the intermediate ring are restrained in the induction hardening process, the occurrence of warpage and undulation is suppressed. Even in the induction tempering process, when the race ring and the intermediate ring are restrained, the occurrence of warpage and undulation is further suppressed. Furthermore, the surface hardness and the internal hardness of the raceway ring and the intermediate ring are both HV653 or higher in terms of Vickers hardness. Next, a finish is made by, for example, a tumbler without performing a cutting process such as a turning process or a grinding process.

According to the above manufacturing process, the formation of the austenite grain boundaries before cooling is not completely performed. Therefore, when this raceway ring and intermediate ring are applied to the thrust receiving mechanism 8 as described above, the roller is subjected to dilute lubrication. Even if there is an oil film breakage (metal contact) between 12 and the raceway ring 9 and the intermediate ring 11 or between the roller 14 and the raceway ring 10 and the intermediate ring 11, resistance to wear, cracking and progress is extremely high. Become bigger. Therefore, it is also effective for surface damage such as abrasion and surface-origin type peeling, and internal origin-type peeling, and the life can be extended.
Since the high-frequency heat treatment equipment is relatively small and does not use carburizing gas or the like that requires attention to handling, the heat treatment equipment can be inlined to form one line together with the processing steps. Therefore, work in progress before and after heat treatment does not occur, thereby reducing the manufacturing cost. Further, since product management becomes easy, quality control of piece-by-piece can be performed, and high quality of the product is realized. Furthermore, in the case of normal atmospheric heat treatment, since it tends to cause warpage and undulation of the race and intermediate wheels at the end of the tempering process, a press temper process for correction is required, but a manufacturing process that employs high frequency heat treatment Then, since such warpage and undulation are unlikely to occur, the press tempering process becomes unnecessary, and this also reduces the manufacturing cost.

  Generally, in the initial stage of the heating process for quenching, there are deformation due to processing stress due to application of temperature, strain release and deformation due to its own weight, and in the subsequent heating process, the metal structure changes from ferrite + cementite to austenite. There is deformation due to transformation to + cementite and deformation due to its own weight, and further deformation due to transformation from austenite + cementite to martensite + cementite. Conventionally, in order to correct this, a step of press quenching is added in the cooling step. Also, in the tempering process, there are deformation due to release of residual stress and transformation from quenched martensite to tempered martensite and transformation from retained austenite to tempered martensite + cementite, in order to correct this, Conventionally, as shown in FIG. 6B, a press tempering process is added. The present invention eliminates such a correction process.

  7 to 9 show examples of the high-frequency heat treatment apparatus used in the manufacturing process of the race rings 9 and 10 and the intermediate ring 11 in this embodiment. In FIG. 7, the high-frequency heat treatment apparatus 18 includes a high-frequency coil 19, a lower restraining jig 20, an upper restraining jig 21, a central shaft 22, and a jig holding nut 23. The high frequency coil 19 has a plurality of cooling water discharge ports 19a for discharging cooling water as indicated by arrows.

  The procedure of the high frequency heat treatment in the high frequency heat treatment apparatus 18 will be described. First, the center shaft 22 is inserted into the lower restraining jig 20 from below, and the ring-shaped track rings 9 and 10 or the intermediate wheel 11 (hereinafter referred to as a ring body in the description of FIGS. 7 to 9) is inserted into the center shaft 22. A plurality of them are fitted concentrically from above and arranged on the smooth upper surface of the lower restraining jig 20. Although one ring body 9 (10, 11) may be arranged, it is desirable that there are a plurality of rings from the viewpoint of improving the efficiency of the high-frequency heat treatment. In the case where a plurality of sheets are subjected to high-frequency heat treatment at the same time, the rings 9 (10, 11) are stacked in a range that can be heated by the high-frequency coils 19 disposed on both sides of the central shaft 22. Next, the upper restraining jig 21 is arranged so that the smooth lower surface thereof is in contact with the upper surface of the uppermost ring body 9 (10, 11) that is stacked. The jig holding nut 23 is fastened to the male screw portion 22a formed on the upper portion of the central shaft 22 with a predetermined torque, whereby the ring bodies 9 (10, 11) are subjected to stress in a direction to press the respective rolling surfaces. The entire rolling part is loaded.

  When a high-frequency current is passed through the high-frequency coil 19, the ring body 9 (10, 11) is heated by high-frequency induction. The ring body 9 (10, 11) is induction-hardened and heated at a temperature equal to or higher than the temperature at which the steel starts to transform from ferrite to austenite, and is held for a predetermined time in this heating state (heating step). Thereafter, energization is stopped and cooling water is sprayed onto the ring body 9 (10, 11) through the cooling water discharge port 19a of the high-frequency coil 19. Thereby, the ring body 9 (10, 11) is rapidly cooled to a temperature at which the austenitized steel starts to martensite (cooling step). According to the above procedure, the ring bodies 9 (10, 11) are hardened and hardened in a state where a stress in a direction to press the rolling surface is applied. Since the heating time in this quenching process is extremely short as compared with atmospheric heat treatment such as carburizing heat treatment, carbonitriding treatment, or bright heat treatment, which is a general quench hardening treatment, the grain boundary oxide layer is hardly formed. In order to perform heating and cooling uniformly at the time of this high-frequency heat treatment, a portion other than the high-frequency coil 19 in the high-frequency heat treatment device 18 is arranged with respect to the high-frequency coil 19 with the central axis 22 as the rotation axis, as indicated by a rotation arrow. It is preferable to rotate relatively.

  Further, the high frequency coil 19 is again energized with a high frequency current, and the ring body 9 (10, 11) is heated to a temperature below the temperature at which the steel starts to transform from ferrite to austenite. Thereafter, the ring body 9 (10, 11) is held at a predetermined temperature for a predetermined time, and then cooled by stopping heating (tempering step). By the above procedure, the ring body 9 (10, 11) is tempered in a state where a stress in a direction to press the rolling surface is applied. At this time, in order to perform heating uniformly, it is preferable that the portion other than the high-frequency coil 19 is rotated about the central axis 22 as a rotation axis, as indicated by an arrow as described above.

Through the above-described steps, the ring body 9 (10, 11) has almost no grain boundary oxide layer formed, and the stress in the direction to press the rolling surface is at least rolling of the ring body 9 (10, 11). It is quenched and tempered while being loaded on the entire running part. The restraining stress due to the restraining jigs 20 and 21 does not necessarily need to be continuously applied in the tempering process and can be released as necessary, but the viewpoint of suppressing deformation and the viewpoint of reducing the number of processes. Therefore, it is desirable to restrain the ring body 9 (10, 11) before the start of the heat treatment and continue to restrain until the end of the heat treatment (end of the tempering step).
According to this high-frequency heat treatment method, the grain boundary oxide layer of the surface layer portion of the ring body 9 (10, 11) that is used without being subjected to cutting such as turning or grinding after being quenched and hardened and tempered. Can be made 1 μm or less in thickness, and warpage and undulation can be reduced.

  FIG. 8 shows a first modification of the induction heat treatment apparatus. This high-frequency heat treatment apparatus 24 has basically the same configuration as the high-frequency heat treatment apparatus 18 shown in FIG. 7, but does not have the center shaft 22 and the jig press nut 23 that meshes with the center shaft 22 as described above. 7 is different from the induction heat treatment apparatus 18 of FIG. 7 in that a high frequency coil 25 is disposed on the inner diameter side of the tempering process in addition to the high frequency coil 19. The high-frequency coil 25 disposed on the inner diameter side is also provided with cooling water discharge ports 25a. Further, the upper restraining jig 27 is loaded with pressure on the ring body 9 (10, 11) disposed on the lower restraining jig 26 by, for example, a hydraulic cylinder. Thereby, the stress of the direction which presses a rolling surface is loaded with respect to the whole rolling part of the ring body 9 (10, 11) at least. And quenching and tempering by high frequency heating are performed not only from the outer diameter side of the ring body 9 (10, 11) but also from the inner diameter side. According to the high frequency heat treatment apparatus 24 of the first modification, the ring body 9 (10, 11) is heated more uniformly. Therefore, it is advantageous for suppressing warpage and swell.

  FIG. 9 shows a second modification of the induction heat treatment apparatus. This high-frequency heat treatment apparatus 28 is also basically configured in the same manner as the high-frequency heat treatment apparatus 18 shown in FIG. 7, but instead of the high-frequency coil 19, a high-frequency coil 29 for quenching and a high-frequency coil 30 for tempering are provided. 7 is different from the high-frequency heat treatment apparatus 18 of FIG. 7 in that they are arranged on both sides of the central axis 31. Further, the quenching high-frequency coil 29 is a second quenching high-frequency coil 29 a and a second quenching high-frequency coil 29 a that is adjacent to the first quenching high-frequency coil 29 a and disposed between the second quenching high-frequency coil 30. It consists of a quenching high frequency coil 29b. The second quenching high frequency coil 29b has a cooling water discharge port 29c. Further, in the high-frequency heat treatment apparatus 18 of FIG. 7, all the arranged ring bodies 9 (10, 11) can be heated at the same time, whereas in this modification, some of the ring bodies 9 (10, 11). Only) is configured to be heatable. Specifically, the heights of the high-frequency coils 29 and 30 are set to be a plurality of ring bodies 9 (10 and 11) set so that only the end faces of some of the ring bodies 9 (10 and 11) can face each other. It is smaller than the height. Furthermore, one or both of the high frequency coils 29 and 30 and the central shaft 31 are movable in the axial direction of the central shaft 31, so that the central shaft 31 can move relative to the high frequency coils 29 and 30. It has become.

  The lower restraining jig 32, the upper restraining jig 33, and the jig holding nut 34 are combined with the central shaft 31 in the same manner as in FIG. The body 9 (10, 11) is clamped by the lower restraining jig 32, the upper restraining jig 33, and the jig presser nut 34 to be in a restrained state. Thereby, the stress of the direction which presses the rolling surface of the ring body 9 (10, 11) is loaded with respect to the whole rolling part of the ring body 9 (10, 11) at least.

  A high frequency current is applied to the high frequency coils 29 and 30, and the central shaft 31 moves relative to the high frequency coils 29 and 30. Accordingly, the ring body 9 (10, 11) reaches a position between the energized first quenching high-frequency coil 29a. Thereby, the ring body 9 (10, 11) is induction-hardened and heated to a temperature equal to or higher than the temperature at which the steel starts to transform from ferrite to austenite. Then, the heated ring body 9 (10, 11) reaches a position sandwiched between the second quenching high-frequency coil 29b while moving relative to the first quenching high-frequency coil 29a. In the meantime, the temperature is maintained at the above temperature for a predetermined time. Thereafter, heating of the ring body 9 (10, 11) by the second quenching high-frequency coil 29b is stopped, and cooling water is blown to the ring body 9 (10, 11) from the cooling water discharge port 29c. The austenitized steel is rapidly cooled to a temperature below the temperature at which martensite formation begins. By the above procedure, the ring body 9 (10, 11) is quenched with a stress applied in a direction to press the rolling surface. Since the heating time in this quenching process is extremely short as compared with atmospheric heat treatment such as carburizing heat treatment, carbonitriding treatment, or bright heat treatment, which is a general quench hardening treatment, the grain boundary oxide layer is hardly formed.

  Further, the ring body 9 (10, 11) moves relative to the high frequency coils 29, 30 and reaches a position sandwiched between the tempering high frequency coils 30. Thereby, the ring body 9 (10, 11) is heated to a predetermined tempering temperature not higher than a temperature at which the steel starts to transform from ferrite to austenite. The heated ring body 9 (10, 11) moves relative to the tempering high-frequency coil 30 and is air-cooled by leaving the heating range after a predetermined time. Thereby, it tempers in the state which loaded the stress of the direction which presses a rolling surface to the ring body 9 (10, 11). Through the above steps, the ring body 9 (10, 11) is quenched and tempered while stress in the direction of pressing the rolling surface is applied to at least the entire rolling portion of the ring body 9 (10, 11). The According to this modification, even if the ring bodies 9 (10, 11) are stacked beyond the length of the high-frequency coils 29, 30, the ring bodies 9 (10, 11) can be heat-treated.

  As a simple method of measuring (selecting) warpage / waviness, there is a method of passing through a slit as shown in FIG. That is, the apparatus shown in FIG. 12 is a slit gauge 35, and the slit gauge 35 has a slit 35a having a width T1 + d. Here, T1 is the thickness of the test piece, and d is the upper limit of warpage / waviness. When a test piece is inserted into the slit 35a, the test piece can pass through if the warp / waviness of the test piece is d or less, but cannot pass through if it exceeds d. As a result, it is possible to select test pieces having warpage and undulation exceeding d. This method is particularly effective in the mass production process and is appropriately employed when selecting a large number of races or intermediate wheels having warpage and undulation exceeding a predetermined value.

Based on the above manufacturing process, a bearing ring or intermediate ring for a thrust receiving mechanism was created. S55C, SAE1070, SK5, and SUJ2 were used as steel plates, and a molded product having an inner diameter of 25 mm, an outer diameter of 40 mm, and a plate thickness of 1 mm was obtained by pressing. Forty test pieces are stacked on the high-frequency heat treatment apparatus 18 shown in FIG. 7, restrained from above and below by the restraining jigs 20 and 21, and heated by the high-frequency coil 19 (10 kHz), and the entire molded product is heated. Then, it was cooled with water to obtain test pieces of Examples 5-8. Moreover, following the same process, the said molded article was hold | maintained at 220-230 degreeC for 10 second with the said restraint state, and induction tempering (induction tempering) was performed, and the test piece of Examples 1-4 was obtained.
Further, SPC, SCM415, SCM420 and SUJ2 are pressed to obtain a molded product, and carburized heat treatment (880 ° C. × 40 minutes + 820 ° C. × 10 minutes, 160 ° C. × 2 hours) or bright heat treatment (850 ° C. × 40 minutes) And subjected to press tempering (warp and swell correction) at 200 ° C. for 1 hour to prepare test pieces of Comparative Examples 1 to 4.

  In Table 1, the hardness was measured using a Vickers hardness meter (1 kgf). In addition, for warpage and undulation, the flatness is measured using a roundness measuring instrument (Talirond 265 manufactured by Taylor Hobson), and the warpage and undulation at the 1 mm position from the inner diameter part, the 1 mm position from the outer diameter part, and the central part are measured. The maximum value was measured as the value of warpage / waviness. FIG. 10 is a schematic plan view showing a measurement part of warpage / waviness of a test piece, and FIG. 11 is a view showing an example of a profile obtained by measurement of warpage / waviness. The broken line part in FIG. 10 is a measurement position of warpage / swell. Further, as shown in FIG. 11, the difference between the highest point and the lowest point of the height was read from the height profile obtained by measurement, and used as the value of warpage / waviness.

  About the test piece after the heat treatment shown below, a cross section perpendicular to the rolling surface is mirror-polished, and the mirror-polished surface is corroded by immersing in a corrosive solution obtained by adding a surfactant to a picric acid saturated aqueous solution. When the central part of the cross section was observed at a magnification of 400 times according to the above, and the ratio of the region closed by the prior austenite grain boundaries to the entire visual field was calculated, all of Examples 1 to 4 of the present invention were 10 It was found that in Comparative Examples 1 to 4, it reached nearly 100%.

  From Table 1, in the case of Examples 1-4 of this invention, it turns out that the surface hardness and internal hardness have ensured HV653 or more all. In the case of Examples 1 to 4 of the present invention, the average of warp / waviness values is 12 to 18 μm and the range is 2 to 26 μm, whereas in the case of Comparative Examples 1 to 4, the average of warp / waviness values is It is 78 to 88 μm and the range is 52 to 168 μm. The embodiment of the present invention is about 1/2 to 1/84 of the comparative example, and it can be seen that the effect of correcting warpage and undulation is large. Moreover, the curvature and the undulation value measurement of Examples 5-8 were implemented similarly to the above. The results are also shown in Table 2. Assuming that the occurrence rate of warpage and waviness in the test pieces of the examples of the present invention is a normal distribution, the measurement was performed with the number of measurement n = 500, and as a result, the average value μ = 12 to 22 μm and the standard deviation σ = 2 to 6 μm. Of normal distribution. A value obtained by adding three times the standard deviation of the warp / waviness value to the average value when the warp / waviness values of the test pieces randomly extracted from the plurality of test pieces is measured is 40 μm or less. It can also be seen that the probability that a specimen having a warp / waviness value of 40 μm or more is detected is 0.1% or less.

  As a reference, when a test piece having an inner diameter of 60 mm, an outer diameter of 85 mm, and a plate thickness of 1 mm was prepared using the materials and manufacturing methods corresponding to Examples 1 to 4 in Table 1, the warpage / waviness value was measured. The maximum value of was 28 μm, and the maximum value was not significantly different from that of Examples 1-4.

  From Table 2, it can be seen that the warp and undulation values of the test pieces of Examples 5 to 8 are 40 μm or less, whereas the warp and undulation values of the test pieces of Examples 1 to 4 are 30 μm or less. In the quenching process until cooling, deformation due to release of processing stress / strain, deformation due to its own weight, and deformation due to phase transformation are deformation factors. In Examples 5 to 8, the restraining jig 20 is used in the quenching process. , 21, the deformation correction is performed at the same time. Further, in the tempering process, deformation due to release of residual stress and deformation due to phase transformation are added as deformation factors. However, since Examples 1 to 4 continue the above-described restraint during this process, Correction is made at the same time, and the difference is considered to be the difference between Examples 5-8 and Examples 1-4. In addition, although the measurement of hardness was also performed, since there was no difference in Examples 5-8 and Examples 1-4, description is abbreviate | omitted in Table 2.

[Allowable static rolling element load test]
Three test pieces of each of Examples 1 to 4 and Comparative Examples 1 to 4 are used (two are race rings and one is an intermediate ring), and rolling elements are used between the race rings and the intermediate rings. A certain roller and a cage for holding the roller were arranged, and an allowable static rolling element load test was performed in the form of a thrust receiving mechanism.
About the said test piece, the load which generate | occur | produces the total plastic deformation of 0.01% of a rolling element (roller) diameter was measured using the Amsler testing machine. It is empirically known that the allowable amount of plastic deformation in the field of rolling bearings is that the sum of the deformation amount of the rolling element and the deformation amount of the raceway is 0.01% or less of the diameter of the rolling element. Such small plastic deformation does not adversely affect the smooth rotation and fatigue life of the bearing under normal load. Based on the allowable static rolling element load test result, the safety factor according to the material (material + heat treatment) of the race and intermediate rings was determined.

The safety factor is defined by the following formula. A smaller safety factor is desirable.
S ₀ = C ₀ / P ₀ max
(S ₀ : allowable safety factor, C ₀ : basic static load rating, P ₀ max: maximum static rolling element load)
Table 3 shows the safety factors of Examples 1 to 4 and Comparative Examples 1 to 4 thus obtained.

As can be seen from the results in Table 3, when Examples 1 to 4 of the present invention were compared with Comparative Examples 1 to 3, the allowable static rolling element load was improved by about 60% or more, and good results were obtained.
In the case of Examples 1 to 4, since the entire race and intermediate ring (the entire test piece) are subjected to high-frequency heat curing treatment, both the surface hardness and the internal hardness are HV653 or more, and the race and intermediate rings are plastically deformed. It is considered that (plastic deformation) hardly occurs, and as a result, the allowable static rolling element load is improved.

Further, Example 4 and Comparative Example 4 are obtained by using the same material and heat-curing the entire race and intermediate ring (the entire test piece), but the heat-curing method is different. In Example 4, the allowable static rolling element load is higher than that of Comparative Example 4.
This is because, in the case of the embodiment of the present invention, by using high-frequency heat treatment, the austenite grain boundaries before cooling are not completely formed, and the crystal grain boundaries are not clearly formed. It is considered that the static rolling element load is high. Similarly, by using high-frequency heat treatment, the grain boundary oxidation of the raceway ring and the intermediate ring can be suppressed, and the grain boundary oxide layer on the surface becomes 1 μm or less and hardly occurs, so that deformation at the surface layer portion is suppressed. Therefore, it is considered that the allowable static rolling element load is high.

[Abrasion amount confirmation test]
A wear amount confirmation test was performed using test pieces obtained by the materials and manufacturing methods corresponding to Example 4 and Comparative Example 4 (however, the dimensions are different from those of the above Examples and Comparative Examples).
As shown in FIG. 17, the testing machine has a thrust receiving mechanism 8 interposed between a first member 33 and a second member 34 that perform eccentric rotational movement between each other, and the first member 33 has a thrust bearing. A thrust load SF is applied via the pressure member 35, the pressure member 36, and the ball 37. The first race ring 9 of the thrust receiving mechanism 8 is fixed to the first member 33, and the second race ring 10 is fixed to the second member 34. The second member 34 in the testing machine is fixed to the base 38. A cylindrical portion 33a protruding from the lower surface of the first member 33 is engaged via a needle bearing 41 with an eccentric shaft portion 40a of a rotary shaft 40 rotatably supported on a base 38 via a bearing 39. The first member 33 performs eccentric rotational movement by the rotation of the rotating shaft 40.

The test conditions are as follows.
Thrust load: 1000N (Load position: Position where the offset amount OFF is 12.5mm from the center)
Rotational speed: 1500 r / min. (Revolution radius (= eccentricity e): 2.5mm)
Lubricant: PAG + white kerosene

  FIG. 18A shows the results of the conventional wear amount confirmation test, and FIG. 18B shows the results of the wear amount confirmation test of the invention product. This figure shows the generatrix curve of the raceway surface.

As can be seen by comparing FIGS. 18A and 18B, the wear amount of the invention product is about 1/5 of the wear amount of the conventional product, and the wear resistance of the invention product is remarkably improved. I understand.
In the case of the example, the warp / waviness is preferably 40 μm or less (see Table 2), so that no contact occurs between the roller and the test piece, which is considered to improve the wear resistance. Also, by applying high-frequency heat treatment, the austenite grain boundaries before cooling are not completely formed, and the crystal grain boundaries are not clearly formed. It is considered that the wear resistance is improved by preventing the occurrence of wear due to the occurrence of wear and increasing the resistance to the occurrence and progress of wear. Similarly, by applying high-frequency heat treatment, grain boundary oxidation on the surfaces of the bearing ring and intermediate ring of the thrust receiving mechanism is suppressed, and the thickness of the oxide layer on the surface becomes 1 μm or less, which is equivalent to being hardly formed. Also in this case, it is considered that wear due to roller sliding can be prevented and the wear resistance is improved.

[Life test]
A life test was performed using the test pieces of Examples 1 to 8 and Comparative Examples 1 to 4. However, in this test, instead of the thrust receiving mechanism, a thrust bearing was assembled using the test piece as a race, and a life test was performed in the form of a thrust bearing. About the roller and the cage, those of a thrust bearing were used. Table 4 shows the test conditions.

  Table 5 shows the life test results. In this life test result, the life of Comparative Example 1 is set to 1, and the relative ratio is shown.

  As can be seen from the results in Table 5, the life of the test pieces of Examples 1 to 8 was improved more than twice as long as the life of Comparative Examples 1 to 4, and good results were obtained. In the case of the example, the warp / waviness is 40 μm or less (see Table 2), so that no contact occurs between the roller and the test piece, and surface damage such as abrasion and surface-origin peeling is prevented. It is thought that it was made. In addition, since the whole is heat-cured by high frequency, the allowable static rolling element load is high, and the warp / waviness is 40 μm or less, so the contact surface pressure is smaller than that of the comparative example, and internal origin type peeling is prevented. It can be considered that it has a long life.

  In addition, by applying high-frequency heat treatment, the austenite grain boundaries before cooling are not completely formed, and the grain boundaries are not clearly formed. Also, it is considered that a long life is obtained by the resistance to the occurrence and propagation of cracks, even with respect to internally-origin-type delamination cracks. Similarly, by applying high-frequency heat treatment, the grain boundary oxidation on the surfaces of the bearing ring and intermediate ring of the thrust receiving mechanism is suppressed, and the thickness of the oxide layer on the surface is 1 μm or less, which is almost not formed. It is considered that a long life is also achieved by preventing the occurrence of cracks.

[Acoustic test]
An acoustic test was performed under the test conditions shown in Table 6 with respect to the relationship between the warp / waviness value and the sound. As for the acoustic test, the thrust bearing was assembled with the test piece and the test was performed in the state of the thrust bearing, as in the life test.

  FIG. 13 shows the relationship between the warp / waviness value of the test piece and the sound. The average of n = 10 in a certain warp / waviness range was adopted as the acoustic value of the acoustic test in FIG. As can be seen from FIG. 13, when the warp / waviness value of the test piece exceeds 45 μm, the sound becomes louder. It can be seen that when the warp / waviness value is 50 μm or more, it shows a large value of 84 dBA or more, and when it is 45 μm or less, it is remarkably small, 81 dBA or less. This is because when the warp / waviness value of the test piece is 45 μm or less, the roller behavior becomes stable and the bearing can rotate smoothly.

  FIGS. 14A and 14B are optical micrographs of the prior austenite grain boundaries, and FIGS. 15A and 15B are schematic views of the prior austenite grain boundaries. Is an example of Example 4, and (B) shows an example of Comparative Example 4. The observation of the prior austenite grain boundaries is as described above, but in more detail, after cutting the raceway ring and the intermediate ring in a plane perpendicular to the rolling surface, and mirror-polishing the cross section, The polished surface was immersed in a corrosive solution at room temperature for 30 minutes to be corroded. As the corrosive solution, a solution obtained by adding a surfactant to a saturated aqueous solution of picric acid (JIS G 0551 Annex 1) was used. Thereafter, the central part of the cross section was observed with an optical microscope at a magnification of 400 times and photographed.

  14 and 15, a clear prior austenite grain boundary is observed in the comparative example of FIG. 14 (B), whereas in the example of the present invention of FIG. 14 (A), the prior austenite grain boundary is observed. Is observed to be ambiguous. In the case of the comparative example, it is considered that the formation of the prior austenite crystal grain boundary has sufficiently progressed as shown in FIG. 15B, and therefore the crystal grain boundary was clearly observed. On the other hand, in the case of the embodiment of the present invention, as shown in FIG. 15A, the formation of the prior austenite crystal grain boundary did not sufficiently proceed, and therefore the crystal grain boundary was not clearly observed. Conceivable. From this, it is understood that in Examples 1 to 4 of the present invention, the formation of prior austenite grain boundaries does not proceed as much as in Comparative Examples 1 to 4.

  16 (A) and 16 (B) are optical micrographs of the surface layer portions of the raceway ring and the intermediate ring (test piece), (A) is an example of Example 4, and (B) is an example of Comparative Example 4. Is shown. This optical micrograph was obtained by the following procedure. That is, the raceway ring and the intermediate ring were cut at a plane perpendicular to the rolling surface, and the cross section was mirror-polished, and then the polished surface was immersed and corroded in 3% night at room temperature. Although the immersion time is 2 to 10 seconds, since the susceptibility to corrosion varies depending on the steel type, appropriate time was set for each of the race and intermediate rings while confirming the progress of corrosion. Thereafter, the surface layer portion directly under the rolling surface was observed with an optical microscope and photographed. As a result of this optical microscope observation, in the example of the present invention, the layer thickness of the grain boundary oxide layer in the surface layer portion is 1 μm or less, and in the comparative example, the layer thickness of the grain boundary oxide layer in the surface layer portion is about 6 μm. I understood.

In the above embodiment, the cages 13 and 15 are only synthetic resin cages. However, the cages 13 and 15 may be of various shapes such as a box cage and an aluminum cage. Is possible. In addition, the cages 13 and 15 are manufactured by injection molding in the case of a synthetic resin body, but are also applicable to a machined cage, and other than the synthetic resin body, a machined cage, a press cage, etc. Those made by various manufacturing and processing methods are also applicable.
Further, the thrust receiving mechanism of the present invention is desirably employed in a scroll compressor used in a natural refrigerant (CO2) and PAG oil environment, but is not limited to this, and is used under other lean lubrication and high loads. Useful for compression.
In addition, it should be considered that the embodiments disclosed in this specification are illustrative and non-restrictive in every respect. The scope of the present invention is shown not only by the above description but also by the scope of claims, and is intended to include all modifications within the scope equivalent to the scope of claims.

It is sectional drawing of the thrust receiving mechanism concerning one Embodiment of this invention. It is the II-II arrow directional view of FIG. It is a disassembled perspective view of the thrust receiving mechanism. It is the IV-IV sectional view taken on the line in FIG. It is sectional drawing of the scroll compressor provided with the thrust receiving mechanism. (A), (B) is a figure which shows an example of the manufacturing process of the bearing ring and intermediate ring of one embodiment of this invention and the thrust receiving mechanism of a prior art example, respectively. It is a schematic longitudinal cross-sectional view which shows the example of the high frequency heat processing apparatus used by the manufacturing process of the bearing ring and intermediate | middle ring of this invention. It is the same figure which shows the 1st modification of the same high frequency heat processing apparatus. It is the same figure which shows the 2nd modification of the same high frequency heat processing apparatus. It is a schematic plan view which shows the measurement site | part of the curvature and the wave | undulation of a test piece. It is a figure which shows an example of the profile obtained by the measurement of the curvature and wave | undulation of a test piece. It is a perspective view which shows an example of the measuring method of the curvature and the wave | undulation of a test piece. It is a graph which shows the relationship between a curvature and a wave | undulation value, and a sound. (A) and (B) are optical micrographs of prior austenite grain boundaries, (A) is an example of Examples 1 to 4, and (B) is an example of Comparative Examples 1 to 4. is there. (A), (B) is a schematic diagram of a prior austenite grain boundary, (A) is an example of Examples 1-4, (B) shows an example of Comparative Examples 1-4. . (A), (B) is an optical micrograph of the surface layer part of a raceway ring or an intermediate ring, (A) is an example of Examples 1-4, and (B) is an example of comparative examples 1-4. It is shown. It is sectional drawing which shows the testing machine of an abrasion amount confirmation test. It is a graph which shows the result of the wear amount confirmation test.

Explanation of symbols

3 ... 1st member 4 ... 2nd member 8 ... Thrust receiving mechanism 9 ... 1st track ring (ring body)
10 ... Second race ring (ring body)
11 ... Intermediate wheel
12 ... First roller 13 ... First cage 13a ... Pocket 14 ... Second roller 15 ... Second cage 15a ... Pocket S ... Scroll compression

Claims (10)

A thrust receiving mechanism for supporting a thrust load interposed between the first member and the second member that perform eccentric rotational movement between each other, the first bearing ring fixed to the first member; A second race ring fixed to the second member, an intermediate ring arranged between the first race ring and the second race ring, and a plurality arranged between the first race ring and the intermediate ring Between the first roller, the first cage having a plurality of pockets for holding the first roller so that the rolling axes are parallel to each other, and the second raceway ring and the intermediate ring A plurality of second rollers disposed on the second roller, and a second retainer having a plurality of pockets for holding the second rollers such that their rolling axes are parallel to each other. The rolling shaft center of the second roller and the rolling shaft center of the second roller are orthogonal to each other, and pass through the first track ring and the first cage from the first member, and the intermediate wheel. And a second guide pin extending from the second member through the second race and the second cage to the intermediate ring, The guide pin is movable in the direction perpendicular to the rolling axis of the first roller within the restriction range of the first cage and intermediate wheel, and the second guide pin is perpendicular to the rolling axis of the second roller. In the thrust receiving mechanism, characterized in that it is movable within the restricted range of the second cage and the intermediate wheel in the direction to
At least one of the first and second race rings and the intermediate ring, each of which is a ring body, is hardened and hardened by induction heat treatment and tempered. The cross section perpendicular to the surface is mirror-polished, and the mirror-polished surface is corroded by immersion in a corrosive solution obtained by adding a surfactant to a saturated aqueous picric acid solution, and the central portion of the cross section is observed at a magnification of 400 times using an optical microscope. In this case, the thrust receiving mechanism is characterized in that the area closed by the prior austenite grain boundaries is 10% or less of the entire visual field.   2. The surface layer portion according to claim 1, wherein the at least one of the first and second race rings and the intermediate ring is used without performing turning or grinding after the tempering. A thrust receiving mechanism in which the grain boundary oxide layer has a thickness of 1 μm or less.   In Claim 1 or Claim 2, said at least one ring body of said 1st, 2nd track ring and intermediate ring is used without performing a turning process or a grinding process after said tempering. In addition, an average value obtained by adding three times the standard deviation of warpage / waviness to an average value when the warpage / waviness of a ring extracted at random from a group of the plurality of ring bodies is measured is 40 μm or less. Thrust receiving mechanism that is taken from the group of.   4. The method according to claim 1, wherein at least one of the first and second race rings and the intermediate ring is used without performing turning or grinding after the tempering. The probability that a ring body having a warp / waviness of 40 μm or more is detected when the warp / waviness of a ring body randomly extracted from the group of the plurality of ring bodies is measured is 0.1. Thrust receiving mechanism that is taken from a group of rings that are less than or equal to%.   The thrust receiving mechanism according to any one of claims 1 to 4, wherein the surface hardness and the internal hardness of the raceway ring and the intermediate ring are HV653 or more.   The thrust receiving mechanism according to any one of claims 1 to 5, wherein the material of the race ring and the intermediate ring is steel containing 0.4 mass% or more of carbon.   The thrust receiving mechanism according to any one of claims 1 to 6, wherein the raceway ring and the intermediate ring are formed by pressing a steel plate.   The thrust receiving mechanism according to any one of claims 1 to 7, wherein the raceway ring and the intermediate ring are used in a CO2 refrigerant and PAG oil environment.   A method of manufacturing a bearing ring or an intermediate ring of a thrust receiving mechanism, in which a material is subjected to plastic working and formed into a predetermined shape, and the workpiece formed in the press working step is held so as not to be deformed A method of manufacturing a race ring or an intermediate ring of a thrust receiving mechanism.   The method for manufacturing a bearing ring or an intermediate ring of a thrust receiving mechanism according to claim 9, further comprising a tempering step of performing induction tempering while maintaining a state in which the workpiece is held in the quenching step.

Images