Roller manufacturing mold, roller manufacturing method, and bearing

Abstract

To provide a method for manufacturing a roller in a good yield by suppressing the crack of a mold, and a bearing using the roller.SOLUTION: A die for producing rollers, for deforming a roller material to match a cavity formed when an upper die and a lower die are fitted together, is characterized in that the die comprises an upper nib provided with a material harder than the roller material in order to form the cavity in the upper die, and an upper case arranged with a material different from the upper nib so as to cover the side peripheral surface of the upper nib, and the side peripheral surface of the upper nib is tapered toward the fitting surface and pressed by the case so that the position of the upper nib is not displaced by pressure for crushing the roller material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a mold for manufacturing rollers used in roller bearings, a method for manufacturing rollers using the mold, rollers manufactured by the method, and bearings using the rollers. [Background technology]

[0002] Rolling bearings are used for axles and other bearings because of their low rotational friction. Rolling bearings have multiple rolling elements (rollers) between the shaft (inner ring) and raceway (outer ring). Types of rolling elements include ball bearings, cylindrical roller bearings, barrel-shaped spherical roller bearings, and tapered conical roller bearings. In addition to bearings that support loads perpendicular to the shaft (radial), there are also thrust bearings that support loads parallel to the shaft (axial).

[0003] In the case of roller bearings, which use rollers as the rolling elements, the rollers are mainly made of metal and are formed by turning, which cuts the material, or by forging using dies. Turning is done using an NC lathe, which is numerically controlled by a computer, to cut out the material with a cutting tool while rotating it. It is possible to process complex shapes, but as the shapes become larger, a large amount of shavings is produced, resulting in a lot of wasted material.

[0004] Furthermore, in forging, material is placed between dies and crushed to cause plastic deformation. Methods include hot forging, in which the material is heated and shaped in a soft state, and cold forging, in which the material is processed at room temperature, and these methods have short processing times and little material loss. Patent Document 1 also discloses a method for manufacturing tapered rollers that allows for precise finishing of the axial length, and an invention for a tapered roller bearing using this method. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5042957 Summary of the Invention [Problem to be solved by the invention]

[0006] In the case of forging, material waste can be reduced, but if a large amount of pressure is applied to prevent a gap from forming when the upper and lower dies of the die are closed, the die may be overloaded and cracked.Therefore, one method is to fill the die with material by creating a gap in the die and allowing the material to protrude, and then remove the resulting burrs later.

[0007] However, if hardness is required for the rollers, the mold must be made of a metal harder than the rollers, otherwise the mold will deform or crack. Also, if you do not take into consideration how the material will expand when it is crushed, the internal pressure will be too great and the mold will crack.

[0008] In particular, as the size of the roller increases, it becomes more difficult to precisely machine the spherical surface, and the size of the mold also increases, which can increase costs depending on the material. In such situations, it is important to design the mold so that it does not chip.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method for manufacturing rollers with high yield while suppressing cracking of the mold, and a bearing using such rollers. [Means for solving the problem]

[0010] In order to solve the above problems, the roller manufacturing mold of the present invention is a roller manufacturing mold for deforming a roller material to fit the cavity formed when an upper mold and a lower mold are mated, and is characterized in that it has an upper nib made of a material harder than the roller material to form the cavity in the upper mold, and an upper case made of a material different from the upper nib so as to cover the side surface of the upper nib, and the side surface of the upper nib is tapered toward the mating surface and pressed down by the case so that the position of the upper nib does not shift due to the pressure that crushes the roller material.

[0011] The roller manufacturing mold has a lower nib made of a material harder than the roller material to form the cavity in the lower mold, and a lower case made of a material different from that of the lower nib to cover the side surface of the lower nib, and is characterized in that a gap is secured between the mating surfaces of the upper nib and the lower nib, and the roller material is filled into the cavity by being pushed out into the gap when it is stretched so as to expand from the center of the cavity.

[0012] In the roller manufacturing mold, a groove larger than the gap is formed on the mating surface of the upper nib, and the roller material that tends to protrude into the gap is directed upward, thereby dispersing the pressure within the cavity.

[0013] The method for manufacturing a roller according to the present invention is characterized in that cold forging is performed using the roller manufacturing die.

[0014] The present invention also provides a bearing that uses rollers manufactured by the above-described roller manufacturing method. [Effects of the Invention]

[0015] According to the present invention, rollers and bearings can be manufactured with high yields by suppressing die cracking. By using cold forging, which deforms the material to fit the die, rather than turning, which produces a lot of material shavings, material waste can be reduced. Costs can be reduced by using dies that combine expensive, hard materials with other materials.

[0016] Die chipping can be prevented by considering the thickness and combination of the die material, the location and size of the gap to release internal pressure, how the material will stretch, etc., in accordance with the shape and size of the roller. Extending the life of the die also helps maintain product precision and improve yields. [Brief explanation of the drawings]

[0017] [Figure 1]1A and 1B are diagrams showing a roller manufactured using a roller manufacturing die according to the present invention and a bearing using the roller. [Figure 2] 1A to 1C are diagrams showing steps in a method for manufacturing a roller according to the present invention. [Figure 3] 1 is a cross-sectional view showing a mold for manufacturing a roller (spherical roller) according to the present invention. [Figure 4] FIG. 2 is a diagram showing the state after forging using the roller manufacturing die (spherical roller) of the present invention. [Figure 5] 1 is a diagram showing a spherical roller forged using a roller manufacturing die according to the present invention. FIG. [Figure 6] 1 is a graph showing the load applied to a roller manufacturing die (spherical roller) according to the present invention. [Figure 7] 1 is a cross-sectional view showing a roller manufacturing die (conical roller) according to the present invention. [Figure 8] FIG. 2 is a diagram showing the state after forging using the roller manufacturing die (conical roller) of the present invention. [Figure 9] 1 is a view showing a conical roller forged using a roller manufacturing die according to the present invention. FIG. [Figure 10] FIG. 2 is a diagram showing the load applied to a roller manufacturing die (conical roller) according to the present invention. [Figure 11] 1 is a graph showing the load applied to a roller manufacturing die (conical roller) according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. [Example]

[0019] Figure 1 shows (b) cylindrical rollers, (c) spherical rollers, and (d) tapered rollers manufactured using a roller manufacturing die, as well as (a) a bearing using these rollers. As shown in Figure 1(a), bearing 100 is a roller bearing having an inner ring 110 connected to a central axis, an outer ring 120 that rotates around the inner ring 110 as the rotation axis, and multiple rollers 200 interposed between the inner ring 110 and the outer ring 120. The outer peripheral surfaces of rollers 200 contact the inner ring 110 and outer ring 120, and as rollers 200 rotate, inner ring 110 or outer ring 120 is supported rotatably with little resistance.

[0020] The rollers 200 include cylindrical rollers 200a shown in Fig. 1(b), spherical rollers 200b shown in Fig. 1(c), and conical rollers 200c shown in Fig. 1(d). The size of the rollers 200 is about 10 to 150 mm in diameter and about 10 to 150 mm in length.

[0021] The cylindrical roller 200a is cylindrical with a straight outer circumferential surface from the top to the bottom. The spherical roller 200b is barrel-shaped with a curved outer circumferential surface that bulges from the top to the bottom. The conical roller 200c is truncated cone-shaped with a tapered outer circumferential surface that slopes downward.

[0022] Figure 2 shows the steps in the roller manufacturing method. As shown in Figure 2, in conventional turning, the rollers are first formed through the processes of material management, round bar cutting, and NC turning. The spherical rollers 200b are then polished through heat treatment, surface grinding, outer periphery grinding, outer periphery superfinishing, and barreling. Finally, they are inspected through visual inspection and shipping inspection, and for the spherical rollers 200b, dimensional sorting is performed after the visual inspection.

[0023] In the present invention, rollers 200 are manufactured by forging using a roller manufacturing die. The forging process involves material management, cutting of the round bar, outer periphery grinding, press processing, strip grinding for cylindrical rollers 200a, and lathe processing for conical rollers 200c. Spherical rollers 200b are polished, and finally, inspection is performed in the same manner.

[0024] Material management is primarily the process of procuring materials for Coro 200 and managing the material diameter, quality, and weight. Round bar cutting is the process of cutting material to the quality and diameter that matches the product number. NC turning is the process of cutting material on a numerically controlled lathe to create shapes with an accuracy of 1 / 100th of a millimeter, including the recess diameter, body radius, and chamfer radius that match the product. The recess is a depression made to reduce the load of polishing, and the radius is created by rounding the outer surface of the body or by chamfering the corners.

[0025] Peripheral grinding is the process of cutting off only the outer diameter of the cut round bar and adjusting the volume of the material. When the processing ability for cutting the round bar was low, the curved flat surface was polished to make it even, but if it can be cut accurately using a carbide cutting machine, the flat surface grinding process can be skipped.

[0026] In press working, material with a regulated volume is forged using a die. Die forging is a processing method in which the material is placed between dies and crushed to deform it to fit the shape of the die, and is done at room temperature using cold forging.

[0027] Although cold forging requires more force to deform than hot forging, which heats the material and processes it in a soft state, it reduces the energy and time required for processing, improves dimensional accuracy, and produces a smooth surface. However, if the volume of material is too large or too small, it becomes difficult to achieve precision in the product.

[0028] Band grinding is a process in which, when material is pressed into a mold, it is crushed so hard that the material escapes into gaps such as the joints in the middle of the mold, creating band-like protrusions (burrs).Bands tend to appear in products that are difficult to form, and the appearance of bands increases the load.

[0029] In the case of spherical roller 200b, the body is rounded, so the dimensions are controlled without hitting it hard enough to create burrs, but in the case of cylindrical roller 200a, the body is straight, so bands appear, so it is ground to make it straight.

[0030] In the case of the tapered roller 200c, a gap is provided in the die so that burrs are formed when pressed, so the lathe processing is a process for processing the burrs.

[0031] Heat treatment is a process in which heat is applied to a molded product to harden it. Surface grinding is a process in which the flat surface of the product that has been hardened by heat treatment is polished to an accuracy of microns. Peripheral grinding is a process in which the finished product is finished to dimensions in 1 / 1000 units.

[0032] Peripheral superfinishing is a process to improve the roughness of the surface and make it smooth. Since the roller 200 rotates at high speed, if the roughness is not improved, it will affect its lifespan. The roughness (arithmetic mean roughness) at the time of molding is Ra2.0 to 4.0, and it is finished to around Ra0.1.

[0033] The barrel process involves putting the product into a polishing machine along with abrasives and compounds (auxiliaries) and applying rotation and vibration to improve the roughness and round off burrs. Depending on the product, the barrel process may be skipped.

[0034] Visual inspection is a process in which the surface of the product is inspected visually or automatically. Dimensional selection is a process in which dimensions are selected through visual inspection to determine which bearing 100 the product will be assembled into. Shipping inspection is a process in which finished products are sampled to check whether they meet the required precision. [Example]

[0035] Fig. 3 is a cross-sectional view of a roller manufacturing die (spherical roller). Fig. 4 is a diagram showing the state after forging using the roller manufacturing die (spherical roller). Fig. 5 is a diagram showing the pressure applied to (a) a spherical roller forged using the roller manufacturing die and (b) the die. Fig. 6 is a graph showing the load applied to (a) the upper die (punch) and (b) the lower die (die) of the roller manufacturing die (spherical roller).

[0036] As shown in Figure 3, the mold 300 is used to manufacture a roller 200 (here, a spherical roller 200b) by deforming material 210 to fit a cavity 380 formed when an upper mold 300a and a lower mold 300b are mated, and is made up of a combination of a nib 310, a case 320, a case 330, a case 340, a pin 350, etc.

[0037] The upper mold 300a and the lower mold 300b are identical and symmetrical from top to bottom. The nib 310 is an upper nib 310a and a lower nib 310b, the case 320 is an upper case 320a and a lower case 320b, the case 330 is an upper case 330a and a lower case 330b, the case 340 is an upper case 340 and a lower case 340b, and the pin 350 is an upper pin 350a and a lower pin 350b.

[0038] For example, bearing steel (SUJ), which is primarily used for bearings, may be used as material 210. Bearing steel is a high-carbon chromium bearing steel that contains approximately 1% carbon and 1% chromium, and has excellent wear resistance, load capacity, corrosion resistance, hardenability, and the like.

[0039] Upper mold 300a is generally cylindrical, with upper cases 320a, 330a, and 340a arranged around upper nib 310a for forming cavity 380, and with upper pin 350a passing vertically through the center. Lower mold 300b is also generally cylindrical, with lower cases 320b, 330b, and 340b arranged around lower nib 310b for forming cavity 380, and with lower pin 350b passing vertically through the center.

[0040] The nib 310 is a component that compresses the material 210 to form the desired shape, and is provided with projections and recesses to match that shape. The cavity 380 is the space formed by the projections and recesses when the lower surface (mating surface 370a) of the upper nib 310a and the upper surface (mating surface 370b) of the lower nib 310b are mated, and may be provided according to the outer shape of the roller 200. The pin 350 passes through the center of the nib 310, giving it a cylindrical shape.

[0041] Nib 310 needs to deform material 210 by pressure, so it is preferable to use a material harder than material 210, such as cemented carbide. Cemented carbide includes those made by mixing and sintering tungsten carbide with a binder, and is used in applications where wear resistance is required because it has high hardness and does not lose much hardness at high temperatures, but it has low toughness and is expensive.

[0042] The pin 350 is a member that passes vertically through the center of the mold 300 to the cavity 380, and by protruding toward the cavity 380, a recess is formed in the roller 200 when the material 210 is molded. The pin 350 is made, for example, from bearing steel molded into a rod shape. It can be made harder than the material 210 by quenching.

[0043] The recess is a circular depression, and the depth and diameter of the recess can be adjusted by changing the length and diameter of the pin 350. For example, the diameters of the upper pin 350a and the lower pin 350b may be changed, or the recess may be formed only on the upper surface of the roller 200, and not on the lower surface.

[0044] The cases 320, 330, and 340 are used to hold the nib 310 and pin 350 and integrate them into the mold 300. Note that burrs on the corners can create gaps that can lead to cracks, so it is preferable to remove the burrs and round them off. Combining multiple cases 320, 330, and 340 makes it possible to adjust the gaps and absorb vibrations.

[0045] Making the mold 300 using only the nib 310 would increase costs and make it more susceptible to cracking due to impact or distortion, so it is held in place with a material different from the nib 310, such as alloy tool steel cases 320, 330, and 340 made of SKD or other alloy tool steel. Alloy tool steel is made by adding 3% or more of chromium to carbon tool steel containing about 1% carbon, and adding tungsten or other materials.

[0046] The upper case 320a is arranged laterally adjacent to the outer side of the upper nib 310a and is annularly disposed to cover the side surface 360a of the upper nib 310a. To prevent the upper nib 310a from shifting position due to the pressure applied when the material 210 is crushed within the cavity 380, the side surface 360a of the upper nib 310a is tapered so that the lower surface is narrower than the upper surface of the upper nib 310a. For example, the side surface 360a may be inclined at an angle of approximately 1 to 8 degrees.

[0047] Upper case 330a is disposed above upper nib 310a and is annularly arranged to support upper pin 350a. Upper case 340a is adjacent to upper case 320a and upper case 330a laterally outward and is annularly arranged to support the entire structure. Lower cases 320b, 330b, and 340b are similarly symmetrical.

[0048] As shown in FIG. 4, when upper mold 300a and lower mold 300b are pressed together by press working, material 210 placed in cavity 380 is crushed and deformed to fit the shape of cavity 380, and is formed into spherical roller 200b.

[0049] The material 210 is pressed and stretched so as to spread from the center of the cavity 380 toward the inner surface. A gap 390 of approximately 1 to 10 mm is secured between the mating surface 370a of the upper nib 310a and the mating surface 370b of the lower nib 310b. By releasing the pressure inside the cavity 380, cracking of the mold 300 is suppressed, and excess material 210 protrudes into the gap 390, filling the cavity 380 with material 210 and achieving the desired shape.

[0050] As shown in Figure 5(a), if there are band-shaped burrs 220 on the molded material 210, they are scraped off. The peripheral surface 250 of the spherical roller 200b has a curved shape that bulges outward. In addition, recesses 260 are formed on the upper surface 230 and the lower surface 240 of the spherical roller 200b by the upper pins 350a and the lower pins 350b.

[0051] As shown in Figure 5(b), the lines are densely packed on the inner surface of the nib 310, especially on the middle mating surface 370, indicating that strong pressure is being applied. Also, as shown in Figures 6(a) and 6(b), as the movement distance of the upper die 300a and the lower die 300b increases, the load increases and rises sharply at a certain point. This is because if the material 210 is crushed forcefully, the material 210 will stick to the inner surface of the nib 310, and burrs 220 will quickly appear, resulting in strong pressure.

[0052] By providing a gap 390 in the mold 300, the pressure inside the cavity 380 is reduced, and further, the pressing is performed by appropriately adjusting the moving distance and moving speed of the mold 300, taking into consideration the way in which the material 210 stretches depending on the size of the material 210. Note that the dimensions may be controlled by not hitting the material hard enough to produce burrs 220.

[0053] The cylindrical roller 200a is similar to the spherical roller 200b, but the spherical roller 200b has a rounded peripheral surface 250 and can be adjusted so that burrs 220 do not appear. However, the cylindrical roller 200a has a straight peripheral surface 250, so burrs 220 appear. Therefore, the peripheral surface 250 is smoothed by strip grinding. [Example]

[0054] Fig. 7 is a cross-sectional view of a roller manufacturing die (conical roller). Fig. 8 is a diagram showing the state after forging using the roller manufacturing die (conical roller). Fig. 9 is a diagram showing (a) a conical roller before processing and (b) a conical roller after lathe processing, which are forged using the roller manufacturing die. Fig. 10 is a diagram showing the load applied to the roller manufacturing die (conical roller) in the cases of (a) with burrs and (b) without burrs. Fig. 11 is a graph showing the load applied to the roller manufacturing die (conical roller).

[0055] 7, the mold 400 is for manufacturing the roller 200 (here, the conical roller 200c) by deforming the material 210a to fit the cavity 480 formed when the upper mold 400a and the lower mold 400b are mated, and a nib 410, a ring 420, a liner 430, a case 440, a pin 450, etc. are combined. The material 210a is the same as the material 210.

[0056] The upper mold 400a is generally cylindrical, and has an upper liner 430a and an upper case 440a arranged around an upper nib 410a for forming a cavity 480, with an upper pin 450a passing vertically through the center. The lower mold 400b is generally cylindrical, and has a lower ring 420b, a lower liner 430b, and a lower case 440b arranged around a lower nib 410b for forming a cavity 480, with a lower pin 450b passing vertically through the center.

[0057] Nib 410 is a component for compressing material 210a to form the desired shape, similar to nib 310, and is provided with projections and depressions to match the shape. Because nib 410 needs to deform material 210a with pressure, it is preferable to use a material harder than material 210a, such as a cemented carbide alloy.

[0058] The upper nib 410a has the shape of the shallow portion of the wide bottom surface of the conical roller 200c, and the lower nib 410b has the shape of the deep portion of the narrow top surface of the conical roller 200c. Most of the cavity 480 may be on the lower nib 410b side.

[0059] The cavity 480 is a space formed by the unevenness when the lower surface (mating surface 470a) of the upper nib 410a and the upper surface (mating surface 470b) of the lower nib 410b are mated, and may be formed by the outer shape of the roller 200. Note that the pin 450 passes through the center of the nib 410, making it cylindrical.

[0060] Like pin 350, pin 450 is a member that passes vertically through the center of mold 400 to cavity 480, and by protruding toward cavity 480, a recess is formed in roller 200 when material 210a is molded.

[0061] The ring 420, liner 430, and case 440, like the cases 320, 330, and 340, are intended to hold the nib 410 and pin 450 and integrate them into the mold 400. By combining the ring 420, liner 430, and case 440, it is possible to adjust the gap and absorb vibrations.

[0062] If the mold 400 is made using only the nib 410, the cost will be high and it will be prone to cracking due to impact or distortion, so the nib 410 is held in place by a material different from that of the ring 420, liner 430, and case 440 made of alloy tool steel such as SKD.

[0063] The upper case 440a is adjacent to the upper nib 410a in the outward lateral direction and is arranged in an annular shape to cover the side peripheral surface 460a of the upper nib 410a. It also is adjacent to the upper liner 430a in the outward lateral direction and supports the entire upper case 440a. The lower case 440b is adjacent to the lower ring 420b and the lower liner 430b in the outward lateral direction and supports the entire lower case 440b.

[0064] To prevent the upper nib 410a from shifting position due to the pressure generated when the material 210a is crushed in the cavity 480, the side surface 460 of the upper nib 410a is tapered so that the lower surface is narrower than the upper surface of the upper nib 410a. For example, the side surface 460 may be inclined at an angle of about 1 to 8 degrees. The side surface of the lower nib 410b may also be tapered.

[0065] Since the cavity 480 on the lower nib 410b side is wide, the lower ring 420b tightens the lower nib 410b to prevent it from shifting position, thereby supporting the lower nib 410b so that it does not crack even when pressure is applied. An upper ring may also be placed around the upper rib 410.

[0066] The upper liner 430a is a member for adjusting the gap of the upper die 400a, and is disposed above the upper nib 410a in an annular shape so as to support the upper pin 450a. The lower liner 430b is similar to the upper liner 430a and is symmetrical from top to bottom.

[0067] As shown in FIG. 8, when an upper mold 400a and a lower mold 400b are pressed together by pressing, the material 210a placed in the cavity 480 is crushed and deformed to fit the shape of the cavity 480, and is formed into a conical roller 200c.

[0068] The material 210a is pressed and stretched from the center of the cavity 480 to the inner surface and then upward. A gap 490 is secured between the mating surface 470a of the upper nib 410a and the mating surface 470b of the lower nib 410b. Releasing the pressure within the cavity 480 prevents cracking of the mold 400, and excess material 210a protrudes into the gap 490, filling the cavity 480 with the material 210a and achieving the desired shape.

[0069] Gap 490 may be narrower than gap 390, and a groove 480a larger than gap 490 is provided in the mating surface 470a of the upper nib 410a, and the material 210a that tends to protrude into gap 490 is directed upward, thereby dispersing the pressure within cavity 480. Groove 480a is provided near the front and rear of the cavity 480 entering gap 390.

[0070] As shown in FIG. 9(a), burrs 220a protruding upward from the molded material 210a are removed by lathe machining. As shown in FIG. 9(b), the peripheral surface 250a of the conical roller 200c is tapered from the lower bottom surface (upper surface 230a) side to the upper bottom surface (lower surface 240a) side. A recess 260a is formed on the upper surface 230a of the conical roller 200c by an upper pin 450a. The lower surface 240a of the conical roller 200c is not recessed due to the increased diameter of the lower pin 450b, but recesses may be provided.

[0071] As shown in Figure 10(b), when gap 490 and groove 480a are not provided, lines are densely packed around the edge of upper surface 230a, indicating that strong pressure is being applied. The same is true when only gap 490 is provided but groove 480a is not. As shown in Figure 10(a), when gap 490 and groove 480a are provided, the pressure applied near the edge of upper surface 230a is reduced.

[0072] As shown in Figure 11, the load increases as the distance traveled by the upper die 400a and the lower die 400b increases, and at a certain point it rises sharply. This is because if the material 210a is crushed forcefully, the material 210a will stick to the inner surface of the nib 410, and burrs 220a will quickly appear, causing a large amount of pressure. Note that a similar load is also applied to the knockout pin (KO pin) that is pushed up to remove the lower die 400b from the part below where the lower die 400b is installed.

[0073] By providing a gap 390 and a groove 480a in the mold 400, the pressure inside the cavity 480 is reduced, and further, the pressing is performed by appropriately adjusting the movement distance and movement speed of the mold 400, taking into consideration the stretching of the material 210a according to the size of the material 210a.

[0074] According to the present invention, rollers and bearings can be manufactured with high yields by suppressing die cracking. By using cold forging, which deforms the material to fit the die, rather than turning, which produces a lot of material shavings, material waste can be reduced. Costs can be reduced by using dies that combine expensive, hard materials with other materials.

[0075] Die chipping can be prevented by considering the thickness and combination of the die material, the location and size of the gap to release internal pressure, how the material will stretch, etc., in accordance with the shape and size of the roller. Extending the life of the die also helps maintain product precision and improve yields.

[0076] Although the embodiments of the present invention have been described above, the present invention is not limited to these. [Explanation of symbols]

[0077] 100: Bearing 110: Inner circle 120: Outer ring 200: Koro 200a: Cylindrical roller 200b: spherical roller 200c: Conical roller 210: Material 220: Bali 230:Top surface 240: Bottom surface 250: Peripheral surface 260: Nusumi 300: Mold 300a: Upper mold 300b: Lower mold 310: Nib 320: Case 330: Case 340: Case 350: Pin 360: Side surface 370:Mating surface 380: Cavity 390: Gap 400: Mold 400a: Upper mold 400b: Lower mold 410: Nib 420: Ring 430: Liner 440: Case 450: Pin 460: Side surface 470:Mating surface 480: Cavity 480a: Groove 490: Gap

Claims

1. A roller manufacturing die for deforming a roller material to fit a cavity formed when an upper die and a lower die are mated, an upper nib made of a material harder than the roller material for forming the cavity in the upper die; An upper case made of a material different from that of the upper nib so as to cover the side peripheral surface of the upper nib, The side peripheral surface of the upper nib is tapered toward the mating surface and pressed by the case so that the position of the upper nib does not shift due to the pressure that crushes the roller material. A roller manufacturing die characterized by:

2. a lower nib made of a material harder than the roller material for forming the cavity in the lower die; A lower case made of a material different from that of the lower nib so as to cover the side peripheral surface of the lower nib, A gap is secured between the mating surfaces of the upper nib and the lower nib, and the roller material is filled into the cavity by being pushed out into the gap when being stretched so as to expand from the center of the cavity.

2. The roller manufacturing die according to claim 1.

3. A groove larger than the gap is formed on the mating surface of the upper nib, and the pressure in the cavity is dispersed by directing the roller material that tends to protrude into the gap upward.

3. The roller manufacturing die according to claim 2.

4. Cold forging is performed using the roller manufacturing die according to any one of claims 1 to 3. A method for manufacturing a roller, comprising:

5. A roller manufactured by the roller manufacturing method according to claim 4, A bearing characterized by:

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