The present invention relates to a method for accurately and efficiently manufacturing a heat-treated ring such as a race for the rolling bearing, a manufacturing apparatus which is used in the method, and a rolling bearing incorporating the race manufactured by the manufacturing method.
Conventionally, for example, in the manufacture of races for the thin cross-section rolling bearings, the finished part is made through many processes from the raw material, the processes involving; turning, heat treatment, surface grinding, external rough grinding, internal rough grinding, external finish grinding, and internal finish grinding (for example, see Japanese Patent Publication No. Tokukai Hei 06-246546, and Japanese Patent Publication No. tokukai Hei 06-246547.
However, with the races for the thin cross-section rolling bearings, in the conventional process, deformation due to the chuck in the grinding process and deformation during heat treatment and hardening, are greater than with the races for the general rolling bearings, which becomes a factor for increasing the margin in the grinding process. Moreover, regarding the heat treated thin cross-section race, when it is ground for the internal diameter after being ground for the external diameter, roundness of the external diameter becomes worse in precision due to residual stress in the internal structure. Therefore, roundness must be ensured through multiple process repetition. This causes problems which increase the manufacturing cost due to longer processing time, more manufacturing processes and the like.
An object of the present invention, taking into consideration these problems of the conventional technology, is to ensure precision in roundness and material thickness uniformity in the race for the thin cross-section rolling bearing.
Another object of the present invention is to address; the point of forming a heat treated pipe-shaped material into individual shapes of races, the point of chucking the pipe-shaped material without affecting the diameter of the material, and the point of processing multiple numbers into individual principal race shapes in the chucked condition, in order to solve the problem of significantly suppressing deformation during grinding and heat treatment which occurs in the conventional manufacturing method.
FIGS. 11(a) to 11(k) are a diagram showing a series of steps from turning and grinding of a pipe-shaped material to the cutting-off step, and then turning and grinding of an annular member which has been cut off from the rest of the pipe-shaped material.
The preferred embodiments of the present invention for solving the abovementioned problems are as follows.
A manufacturing method for a race for the rolling bearing comprises the steps of: heat treating a pipe-shaped material formed into a cylindrical shape and provided with a rib section at one end thereof; chucking the one end of the heat treated pipe-shaped material via a clamping jig; forming the other end of the chucked pipe-shaped material into an annular member which is approximate to the desired race shape, via turning and/or grinding; holding the annular member on the side of the other end; cutting off the annular member from the rest of the pipe-shaped material to provide the annular member with an end face on the cut side, and subjecting the end face on the cut side of the annular member to turning and/or grinding.
A specific process for turning, grinding and cutting in the abovementioned process involves, for example: turning an end face on the afore-mentioned other end, that is on the opposite side to the chucked end, an external surface and an internal surface of the pipe-shaped material to form an annular member; then grinding the external surface, the end face and the internal surface of the annular member where a groove for raceway is formed in the internal or external surface; cutting off the annular member from the rest of the pipe-shaped material, then turning the end face on the cut side of the annular member which has been cut-off; and then grinding the end face on the cut side. Moreover, it is possible to omit all the grinding steps, or the grinding steps except for the grinding of the groove for raceway, from the series of steps. Further, it is also possible to omit only the grinding of the end face.
In the abovementioned manufacturing method, the pipe-shaped material used can have the rib section provided either on the internal diameter side or the external diameter side of the pipe-shaped material. The clamping jig used for the abovementioned manufacturing method, is configured to clamp the rib section in the axial direction of the cylindrical shape of the pipe-shaped material.
For the manufacturing apparatus used for manufacturing a race from a pipe-shaped material provided with a rib section at an end thereof and formed into a cylindrical shape, the following apparatus is given as an example. This apparatus comprises: a first spindle which holds one end of the heat-treated pipe-shaped material; a machining unit which forms the other end of the pipe-shaped material retained by the first spindle into an annular member of a desired shape via turning and/or grinding processes and cuts off the annular member from the rest of the pipe-shaped material to provide the annular member with an end face on the cut side; and a second spindle which retains the other end of the pipe-shaped material, and which also retains the annular member which has been cut off from the rest of the pipe-shaped material by the machining unit. The end face on the cut side of the annular member retained by the second spindle is subjected to turning and/or grinding using the machining unit. The first spindle is provided with a clamping jig which clamps the rib section of the material, and a chuck which securely supports the clamping jig.
It is also possible to individually arrange a machining unit which turns and grinds the pipe-shaped material, and a machining unit which turns and grinds the annular member being cut off.
The rib section can be provided on the internal or external diameter side of the pipe-shaped material. The clamping jig is configured to clamp the rib section in the axial direction of the cylindrical shape of the pipe-shaped material.
The second spindle is provided with a support structure for holding the annular member, and is configured to have a retaining face to mate with the annular member so as to attract and hold the annular member by magnetic force of the retaining face.
Moreover, the present invention provides a rolling bearing which is provided with a race with a material thickness ratio up to 4% manufactured via: heat treating a pipe-shaped material formed into a cylindrical shape and provided with a rib section at one end thereof; chucking one end of the heat treated pipe-shaped material via a clamping jig; forming the other end of the chucked pipe-shaped material into an annular member in a predetermined shape via turning and/or grinding; cutting off the annular member from the rest of the pipe-shaped material to form an end face on the cut side of the annular member; and retaining the annular member on the side of the other end and turning and/or grinding the end face formed on the cut side.
In an example, the race can be manufactured by: turning an end face on the afore-mentioned other end, that is the opposite side to the one end chucked, an external surface and an internal surface of the pipe-shaped material to form an annular member; then grinding the external surface, the end face, the internal surface of the annular member where a groove for a race is formed in the internal or external surface; cutting off the annular member from the rest of the pipe-shaped material to form an end face on the cut side of the annular member, then turning the end face on the cut side of the annular member; and then grinding the end face.
In another example, the race can be manufactured by: turning an end face on the afore-mentioned other end, that is the opposite side to the one end chucked, an external surface and an internal surface of the pipe-shaped material to form an annular member; then cutting off the annular member from the rest of the pipe-shaped material to form an end face on the cut side of the annular member, turning the end face on the cut side of the annular member; and then grinding the end face.
In another example, the race can be manufactured by: turning an end face on the afore-mentioned other end, that is the opposite side to the one end chucked, an external surface and an internal surface of the pipe-shaped material to form an annular member; then forming a groove for a race by grinding in the internal or external surface of the annular member; cutting off the annular member from the rest of the pipe-shaped material to form an end face on the cut side of the annular member, then turning the end face on the cut side of the annular member; and then grinding the end face.
In another example, the race can be manufactured by: turning the end face on the afore-mentioned other end, that is the opposite side to the one end chucked, an external surface and an internal surface of a pipe-shaped material to form an annular member; then grinding the external surface and the internal surface of the annular member where a groove for a race is formed on the internal or external surface of the annular member; cutting off the annular member from the rest of the pipe-shaped material to form an end face on the cut side of the annular member, and then turning the end face on the cut side of the annular member which has been cut off.
The race can be manufactured using a pipe-shaped material provided with a rib section on an internal diameter side thereof.
The race can be manufactured using a pipe-shaped material provided with a rib section on an external diameter side thereof.
The race can be manufactured via a clamping jig which clamps the rib section of the pipe-shaped material in the axial direction of the cylindrical shape thereof.
A chamfer section is formed through turning on the respective races.
The aforementioned race for rolling bearing, is directed for example, to a rolling bearing of the thin cross-section type.
According to the present invention, after heat treatment of the pipe-shaped material provided with a radially protruding rib section on one end side, it is possible to considerably suppress deformation during grinding and heat treatment, which occurs in conventional manufacturing methods by processing a single pipe-shaped material into a number of individual principal race shapes in a condition with the rib section chucked via a dedicated clamping jig.
According to the present invention, the pipe-shaped material is clamped by a standard hydraulic chuck. However, since the pipe-shaped material is previously fixed to a dedicated clamping jig and it is the clamping jig itself which is clamped by the chuck, the pipe-shaped material is finished to a high accuracy from the turning process to the final grinding process, without deformation of the material during chucking.
Further, in the bearing made by the present invention, after heat treatment, a chamfer section is necessarily subjected to a hard turning process, so that the externally produced scale due to the heat treatment process is removed. Furthermore, the chamfer section is processed under the same chucking reference as for the ground surface, so that the fact that there is no eccentricity can also be detected from the thickness deviation measurement. In the case of the outer ring, since there is no thickness deviation of the external diameter and chamfer section, then when the bearing is inserted into the housing, insertion is smoothly conducted. In other words, this is advantageous for easy execution.
Hereunder is a description of an embodiment of the present invention with reference to the drawings. The present invention should not be interpreted as being limited to just this illustrated embodiment of the present invention, and suitable design modifications are possible within the scope of the present invention.
The first spindle 11 comprises a general hydrealic chuck 12, a dedicated clamping jig 14 which is adapted to be grasped by the chuck 12, and to clamp the pipe-shaped material W. The second spindle 28 comprises a magnet cluck face plate 29 and a retaining section 30. The machining unit 23 comprises a turning bit 24 and a grinding groove 25 which can be changed in angular position as in
The present invention comprises at least the following manufacturing steps (a) to (e), to provide, for example, a race 4 for a rolling bearing of the thin cross-section type where the material thickness ratio in the race 4 manufactured by these steps is 4% or less, and where a chamfer section r is formed by turning on the race 4 (refer to
(a) heat-treating a pipe-shaped material W formed into a cylindrical shape and provided with a rib section 1 at one end thereof;
(b) chucking one end of the heat treated pipe-shaped material W via a clamping jig 14 provided on the first spindle 11;
(c) forming the other end of the chucked pipe-shaped material W via turning and/or grinding into a predetermined annular shape, which becomes an approximate race shape, to provide an annular member 10 having an end face 5a;
(d) cutting off the annular member 10 from the rest of the pipe-shaped material W to provide the annular member with an end face 5b on the cut side, and holding the annular member 10 with the second spindle 28, and
(e) turning and/or grinding the end face 5b on the cut side of the annular member 10.
The present embodiment is explained using the race 4 for the ball bearing as an example, however, it is not limited to this, and races of other bearing forms such as a roller bearings or the like are possible within the scope of the present invention. Furthermore, the present embodiment is explained using an outer race, however it may of course be applied to an inner race.
Hereunder is a description of details of an embodiment of respective steps, and an apparatus used in the respective processes.
“Heat Treatment Step”
In the present invention, as shown in
This configuration of the pipe-shaped material W is simply an example and is not limiting the present invention.
That is, in the present invention, the rib section 1 is formed into an annular shape (continuous circular shape) having a desired height in the radial direction and a desired width in the axial direction of the pipe-shaped material W. However, for example, the rib section 1 may be intermittently formed around the circumferential direction (a rib section formed as protruding segments spaced at desired intervals around the circumferential direction) of the pipe-shaped material W. Such a pipe-shaped material W is first heat-treated prior to the machining process such as turning by the machining unit 23.
For the heat treatment method, a well known heat treatment method is suitably selected and used. The pipe-shaped material W is made of bearing steel or the like in the embodiment, but not limited to this substance. For example, in the case where the configuration of the second spindle 28 detailed later is adopted, this pipe-shaped material W is desirably able to be magnetically chucked by the magnetic force on the retaining face of the second spindle 28.
“Chucking Step for Pipe-Shaped Material”
After the abovementioned heat-treated pipe-shaped material W is clamped via the dedicated clamping jig 14, the clamping jig 14 is grasped by the tip chuck 12 of the first spindle 11 as shown in
As a result, the pipe-shaped material W is indirectly fixed to the first spindle 11 via the clamping jig 14, and coaxially retained on the tip of first spindle 11 (refer to
Therefore, according to the present invention, since the clamping jig 14 is chucked by the first spindle 11, the thrust due to the chuck 12 is exerted on the clamping jig 14, but is not exerted on the rib section 1. Further, the rib section 1 is clamped by means of the clamping jig 14 in the normal direction to the opposite planes 2 (
Table 1 shows precision in roundness and thickness deviation, comparing the present invention with the conventional technology, wherein the “work” denotes the pipe-shaped material. In Table 1, the chuck pressure of work No.1 is 7 kg/cm2, and the chuck pressures of works No. 2 and No. 3 are 4 kg/cm2.
(*ex dia. = external diameter, in. dia. = internal diameter)
As previously mentioned, the first spindle 11 is provided with the general hydraulic chuck 12 at the tip thereof. The dedicated clamping jig 14 is chucked by the chuck 12, and therefore the pipe-shaped material W that is clamped at one end thereof by the clamping jig 14 is indirectly retained by the hydraulic chuck 12.
The clamping jig 14 adopts a configuration whereby the rib section 1 projecting in the radial direction of the pipe-shaped material W at one end thereof can be clamped in the axial direction (refer to
Regarding the abovementioned clamping jig 14, in the present embodiment, the receiving member 15 is formed in an overall annular shape, and the end face 16 on the outer periphery is formed in an annular shape having a desired height in the radial direction and a desired width in the axial direction of the pipe-shaped material W. The clamping member 19 is formed an overall annular shape of a desired diameter and desired width.
The clamping jig 14 of the present embodiment is simply an example and the present invention is not limited to this embodiment. That is, for example, the receiving member 15 and the clamping member 19 may be intermittently formed around the circumferential direction, and may be any configuration provided that the receiving member 15 and the clamping member 19 are able to clamp the rib section 1. Therefore, the clamping jig 14 and the rib section 1 may be suitably modified in design within the scope of the present invention.
Moreover, in the present embodiment, the construction is such that the rib section 1 of the pipe-shaped material W is clamped by width adjustment of the interval between the receiving member 15 and the clamping member 19 by bolt tightening via the bolts 18. However, it is of course possible to use another member instead of the bolts 18. Further, the configuration may be such that the receiving member 15 and the clamping member 19 themselves have respective clamping configurations on their respective facing surfaces whereby the rib section 1 can be clamped by width adjustment of the interval between them. For example, a male screw section and a female screw section may be directly formed as a unit respectively on the facing surface of the receiving member 15 and on the facing surface of the clamping member 19, giving a configuration for clamping by screwing these together.
Furthermore, in the pipe-shaped material W used in the present invention, instead of the configuration where the rib section 1 protrudes inward in the radial direction from the internal surface of the pipe-shaped material W as with the abovementioned embodiment, the rib section 1 may protrude outward in the radial direction from the external surface. In this case, the clamping jig 14 adopts for example, the configuration exemplified in
That is to say, this clamping jig 14 comprises a receiving member 15 and a clamping member 19. The receiving member 15 has an external diameter d6 such that it can be retained by chuck fingers 13 of the first spindle 11, and a retaining section 21 protrudingly provided on its tip and having a smaller diameter than an internal diameter d5 of the pipe-shaped material W. The clamping member 19 is fastened to the receiving member 15 via bolts 18, and has an insertion aperture 22 with a diameter bigger than an external diameter d7 of the pipe-shaped material W and smaller than an external diameter d2 of the rib section 1. By inserting the retaining section 21 of the receiving member 15 into the inner periphery of the rib section 1, and clamping the clamping member 19 arranged outside of the pipe-shaped material W by the bolts 18, the rib section 1 is clamped in the axial direction between the end face 20 of the clamping member 19 and the end face (stepped section) 16 of the receiving member 15.
“Forming and Cutting Steps of the Annular Member”
As mentioned above, with one end of the pipe-shaped material W retained by the first spindle 11, the other end or free end 3, that is, opposite to the one end of the pipe-shaped material W which is chucked, is continuously processed from hard turning to grinding by a machining unit 23 (FIGS. 11(a) to 11(k)) to form an annular member 10, which is illustrated by fine hatching area in the drawings.
That is to say, firstly, by applying a turning bit 24 of the machining unit 23 to the other end or free end of the pipe-shaped material W, the end face 5a of the annular member 10 is formed through turning (
Further, the turning sequence and grinding sequence for the respective parts are not limited to this, and design modifications are possible within the scope of the present invention.
For the machining unit 23, for example, a CNC lathe with a grinding stone spindle provided with a general turning bit 24 for the turning section and with a general grinding stone 25 for the grinding section, is adopted (refer to
As described above, the connecting part 9 of the annular member 10, which is formed after turning and grinding of the respective parts, is cut off (
In the present embodiment, a retaining section 30 of the second spindle 28 (refer to
“Processing Step of the End Face on the Cut Side”
The annular member 10 of race shape, which is cut-off and separated while being retained by the magnet chuck face plate 29 of the second spindle 28, is subjected at its end face on the cut side to the finishing grinding, retained by the second spindle 28, to give the finished part or race 4 (from
That is to say, in the present embodiment, firstly, with the machining unit 23 which is used for forming the annular member 10, the end face 5b on the cut-off side is turned by the turning bit 24 (
Since the second spindle 28 has the magnet chuck face plate 29, and when the retaining section 30 having an external diameter d8 fitted with the internal diameter of the annular member 10 is inserted into the internal periphery of the annular member 10, the end face 5a is attracted and held by the magnet chuck face plate 29 (refer to
In the present embodiment, the magnet chuck configuration is used. However, the chuck is not limited to this configurations, there being no limitation provided that the configuration is such that the annular member 10 can be retained between the first spindle 11 and the second spindle 28, and that the turning and grinding steps by the machining unit 23 after the cutting-off step are possible while retaining the annular member 10 by the second spindle 28.
In another embodiment in the present invention, for example, it is also possible to omit, from the abovementioned series of processes, all of the grinding processes, or all of the grinding processes except for the grinding for the raceway forming. Moreover, it is also possible to omit only the grinding of the end face.
That is to say, for example, the abovementioned race 4 may be manufactured by turning the end face on the opposite side to the chuck 12, the external surface and the internal surface of the pipe-shaped material W (
Further, it may be manufactured by turning the end face on the opposite side to the chuck 12, the external surface and the internal surface of the pipe-shaped material W (
Furthermore, it may be manufactured by turning the end face on the opposite side to the chuck 12, the external surface and the internal surface of the pipe-shaped material W (
Here
According to the present embodiment, when the annular member 10 (individual shape) is formed before the grinding process, by providing a auxiliary groove or connecting portion for cutting-off the annular member 10 from the rest of the pipe-shaped material W and by minimizing the cutting-off margin, it becomes possible to keep the deformation in the annular member after cutting-off to a minimum.
Moreover, the finishing process for the end face 5b on the cutting-off side of the annular member 10 is conducted while retained by the chuck configuration of the second spindle 28, so that the complete part of race can be finished with a single manufacturing unit 23, giving a significant reduction in manufacturing time.
As to clamping the pipe-shaped material W through the general hydraulic chuck 12 in the embodiment of the present invention, the pipe-shaped material W itself is fixed by the dedicated clamping jig 14 which is in turn clamped by the general hydraulic chuck 12, and therefore the pipe-shaped material W gets rid of any deformation during being chucked, so that high precision finishing is possible from the turning step to the finishing grinding step.
In the rolling bearing produced by way of the present invention, the chamfer section r is subjected to hard-turning after heat-treatment, whereby any scale produced through the heat-treatment step is removed. The chamfer section r is processed with the same chuck reference as the ground surfaces, there is no eccentricity, which is found through measurement of thickness deviation. By applying the present invention to the outer race of a rolling bearing, it becomes easy to insert the rolling bearing into the housing because the outer race has no deviation in outer diameter and material thickness.
Number | Date | Country | Kind |
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JP2002-324436 | Nov 2002 | JP | national |
JP2003-311934 | Sep 2003 | JP | national |
Number | Date | Country | |
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Parent | 10700575 | Nov 2003 | US |
Child | 11477657 | Jun 2006 | US |