JP3810261B2 - Method for manufacturing sintered bearing with inner groove and groove processing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a sintered bearing with an inner circumferential groove having a groove formed on an inner circumferential surface, and a groove processing apparatus for forming the inner circumferential groove. The inner circumferential groove referred to in the present invention is, for example, sandwiched between a dynamic pressure groove formed on a sliding bearing surface or a sliding bearing surface formed on both ends, and has a larger diameter than the sliding bearing surface. Examples thereof include a middle escape portion where the rotating shaft does not contact.
[0002]
[Prior art]
Various methods for forming the dynamic pressure groove and the intermediate relief portion on the inner peripheral surface of the sintered bearing have been proposed, but one of the methods that can be efficiently formed among them is as follows. There is. That is, a core rod having a pattern corresponding to the groove to be formed (dynamic pressure groove or center escape portion) is inserted into the bearing material, the bearing material is compressed, and the inner circumferential surface thereof is the outer circumference of the core rod. The surface of the core rod is transferred to the inner peripheral surface of the bearing material by being in close contact with the surface, and then the bearing material is released from the compressed state. Pull out. A method for forming a dynamic pressure groove applying such a method is described in Japanese Patent Laid-Open No. 10-306827, and a method for forming a middle relief portion is described in Japanese Patent Laid-Open No. 2-107705.
[0003]
[Problems to be solved by the invention]
In the above conventional method, in order to extract the bearing material in which the inner circumferential groove is formed from the core rod, the inner diameter of the bearing material is sufficiently expanded by the spring back, and unevenness on both the outer circumferential surface of the core rod and the inner circumferential surface of the bearing material is generated. It is required not to interfere with each other without meshing. For this reason, it is desirable that the material generates as much springback as possible. However, the spring back of a sintered alloy for general sliding bearings (the ratio of the inner diameter expansion amount of the bearing material when the compression to the outer diameter of the core rod is released) is about 0.2% at most. The uneven unevenness that can be formed on the inner peripheral surface of the plate is equal to the spring back amount at the maximum. In addition, some sintered bearings made of sintered alloys with relatively low density and sintered alloys that are relatively soft and easily plastically deformed, such as copper-based sintered alloys, have almost no springback. It is difficult to form an inner circumferential groove in a simple bearing material.
[0004]
Therefore, the present invention can reliably extract the core rod for forming the inner circumferential groove from the bearing material with little or no springback, and as a result, the inner circumferential groove can be reliably formed in such a bearing material. It is another object of the present invention to provide a method for manufacturing a sintered inner peripheral groove bearing and a groove processing apparatus that can form deeper inner peripheral grooves.
[0005]
[Means for Solving the Problems]
The sintered bearing manufacturing method of the present invention is a cylindrical bearing material comprising a sintered body made of a core rod having a small diameter part for forming a bearing surface and a large diameter part for forming an inner peripheral groove. And then press the part of the outer peripheral surface of the bearing material toward the axis of the core rod to move the bearing material in the radial direction. While decentering The operation of compressing and engraving a part of the large diameter portion on the inner peripheral surface is sequentially performed in the circumferential direction over the entire circumference of the bearing material while releasing the compression operation after the operation, thereby at least the core rod The diameter portion is transferred to the inner peripheral surface of the bearing material, and thereafter, the core rod is relatively extracted from the bearing material.
[0006]
In the manufacturing method described above, the operation of compressing the bearing material in the radial direction and engraving the large diameter portion of the core rod on the inner peripheral surface to form the inner peripheral groove is sequentially performed in the circumferential direction. After this operation is performed over the entire circumference of the bearing material, the large diameter portion of the core rod is transferred to the inner circumferential surface of the bearing material to form an inner circumferential groove. Since the bearing material is always partly compressed in the radial direction, the inner diameter of the small diameter part (bearing surface) of the inner peripheral surface of the bearing material that has been compressed to the entire circumference is set to the large diameter part of the core rod. The diameter can be equal to or larger than the outer diameter of the. For this reason, a core rod can be extracted from a bearing raw material, without a large diameter part interfering with a bearing surface. Therefore, even if the bearing material has little or no springback, the core rod for forming the inner circumferential groove can be reliably extracted, and the inner circumferential groove can be reliably formed in such a bearing material. . Further, the inner circumferential groove can be made deeper. For example, when the bearing material is inserted into the core rod in an interference fit and a slight springback occurs, the large diameter portion of the core rod may interfere with the bearing surface, but the degree is very small. Yes, the core rod can be easily extracted from the bearing material.
[0007]
As described above, the inner circumferential groove of the present invention formed by the large-diameter portion of the core rod includes a dynamic pressure groove, a middle escape portion that is formed between a pair of bearing surfaces and does not contact the rotating shaft, and the like. Can be mentioned.
[0008]
Next, a groove processing apparatus for a sintered bearing according to the present invention includes a cylindrical bearing having a small diameter portion for forming a bearing surface and a large diameter portion for forming an inner peripheral groove, and made of a sintered body. A core rod inserted into the material, a core rod shaft supporting member that supports the core rod, a cylindrical elastic body arranged to surround the bearing material inserted into the core rod, and a circumferentially divided portion on the outer peripheral side of the elastic body And a plurality of pressure chambers to which fluid is supplied, and a part of the elastic body corresponding to each pressure chamber expands and contracts with respect to the axis of the core rod according to the fluid pressure in the pressure chamber. A compression mechanism for holding, compressing or releasing the outer peripheral surface of the bearing material, and a control means for controlling the fluid pressure in the pressure chamber of the compression mechanism. And the control means controls the fluid pressure in the pressure chamber so that the compression and release operations on the outer circumferential surface of the bearing member by a part of the elastic body are sequentially performed in the circumferential direction over the entire circumferential area of the bearing member. It is characterized by that.
[0009]
According to the above apparatus, when a fluid is supplied to the pressure chamber and the pressure in the chamber is increased, a part of the elastic body corresponding to the pressure chamber bulges toward the axial center side of the core rod and presses the outer peripheral surface of the bearing material. And compress. As a result, the large diameter portion of the core rod is stamped on a part of the inner peripheral surface of the bearing material to form the inner peripheral groove. When the fluid is discharged from the pressure chamber to reduce the pressure, the elastic body contracts and leaves the bearing material, and the bearing material is released. The above-described manufacturing method of the present invention is achieved by appropriately controlling the operation of compressing and releasing the bearing material by a part of the elastic body and the procedure of sequentially performing this operation in the circumferential direction over the entire circumference of the bearing material by the control means. Get the action of.
[0010]
Further, another sinter bearing groove processing apparatus according to the present invention includes a small-diameter portion for forming a bearing surface and a large-diameter portion for forming an inner peripheral groove, and is a cylindrical shape made of a sintered body. The core rod inserted into the bearing material, the core rod shaft supporting member that supports the core rod, and the bearing material inserted into the core rod are arranged radially around the core rod so as to be movable forward and backward. A compression mechanism comprising a plurality of horizontal punches and a drive source for moving the horizontal punches forward and backward, and holding, compressing or releasing the outer peripheral surface of the bearing material in accordance with the advancement and retraction of the horizontal punches, and the amount of advancement and retreat of the horizontal punches of the compression mechanism Control means for controlling And the control means controls the drive source so that the operation of compressing and releasing the outer peripheral surface of the bearing member by the lateral punch is sequentially performed in the circumferential direction over the entire peripheral area of the bearing member. It is characterized by that.
[0011]
According to the above apparatus, when the lateral punch is advanced, the lateral punch presses the outer peripheral surface of the bearing material and compresses the bearing material. As a result, the large diameter portion of the core rod is stamped on a part of the inner peripheral surface of the bearing material to form the inner peripheral groove. When the lateral punch is retracted, the lateral punch moves away from the bearing material and the bearing material is released. The operation of the manufacturing method of the present invention is controlled by appropriately controlling the operation of compressing and releasing the bearing material by the lateral punch and the procedure of sequentially performing this operation in the circumferential direction over the entire circumference of the bearing material. obtain.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a groove processing apparatus for a sintered bearing according to an embodiment of the present invention and a procedure for manufacturing a bearing with an inner circumferential groove by the apparatus. First, the configuration of the groove processing apparatus will be described.
[0013]
In the figure, reference numeral 1 is a base, and 2, 3 are a cylindrical upper punch (core rod shaft support member) and a lower punch that can be raised and lowered. The lower punch 3 passes through the base 1 and its upper end is pivotally supported on the base 1. A core rod 20F is inserted into the lower punch 3 from below. A large-diameter portion 21 that slides on the inner peripheral surface of the lower punch is formed slightly above and below the upper end of the core rod 20F, and the other portion is a small-diameter portion 22. The large-diameter portion 21 is for forming a center relief portion of the bearing inner peripheral surface, and the small-diameter portion 22 is for forming a bearing surface of the bearing inner peripheral surface. The stepped portion that transitions from the large-diameter portion 21 to the small-diameter portion 22 is chamfered to form a slope in the illustrated example.
[0014]
The lower end of the core rod 20F is fixed to a lifting ram (not shown) so that the core rod 20F can be raised and lowered. When the upper punch 2 descends, its inner peripheral surface slides into and fits into the small diameter portion 22 at the upper end of the core rod 20F, and pivotally supports the core rod 20F. Reference numeral 10 denotes a cylindrical bearing material made of a sintered body. The bearing material 10 is fitted to the large diameter portion 21 of the core rod 20F and supported on the lower punch 3. The bearing material 10 may be a sintered body or a sized member.
[0015]
On the base 1, a cylindrical rubber press mechanism (compression mechanism) 30 that forms an intermediate escape portion on the inner peripheral surface of the bearing material 10 is provided coaxially so as to surround the core rod 20 </ b> F. The mechanism 30 includes a frame 31, an outer mold 32 fitted inside the frame 31, a rubber mold (elastic body) 33 disposed inside the outer mold 32, and the rubber mold 33 in close contact with the outer mold 32. A pair of upper and lower rings 34 and 35 are fixed. The frame 31, the outer mold 32, and the rings 34 and 35 are rigid bodies made of steel or the like.
[0016]
As shown in FIG. 2, a plurality (eight in this case) of pressure chambers 36 a to 36 h are defined between the outer mold 32 and the rubber mold 33 at equal intervals in the circumferential direction. The outer mold 32 is formed with a plurality of communication holes 32a to 32h communicating with the pressure chambers 36a to 36h, respectively, and the frame 31 is connected to the communication holes 32a to 32h and the outside to communicate air or oil. The fluid supply paths 31a to 31h for supplying the fluid such as to the pressure chambers 36a to 36h through the communication holes 32a to 32h are formed independently for each of the pressure chambers 36a to 36h. Each fluid supply path 31a to 31h is connected to a fluid supply pipe (not shown) branched from a fluid supply source, respectively, and these pipes control the pressure in the pressure chambers 36a to 36h, and A control valve for discharging the fluid in the pressure chambers 36a to 36h is provided.
[0017]
According to the rubber press mechanism 30, when fluid is supplied from the fluid supply passages 31a to 31h to the pressure chambers 36a to 36h through the communication holes 32a to 32h, and the pressure in the pressure chambers 36a to 36h increases, a rubber mold is generated accordingly. 33 bulges inward. The swelled rubber mold 33 is fitted to the large diameter portion 21 of the core rod 20F and presses the outer peripheral surface of the bearing material 10 supported on the lower punch 3. As a result, the bearing material 10 is compressed in the radial direction, the inner peripheral surface thereof is in close contact with the outer peripheral surface of the core rod 20F, and the large-diameter portion 21 is stamped on the inner peripheral surface. When the fluid in the pressure chambers 36a to 36h is discharged and the pressure is lowered, the rubber mold 33 is separated from the bearing material 10 and the bearing material 10 is released. Further, by appropriately determining the pressure in each of the pressure chambers 36a to 36h, the rubber mold 33 can be brought into contact with the bearing material 10 with an appropriate pressure, and the bearing material 10 can be held. Such an operation is performed by a control circuit (not shown) appropriately controlling the flow rate of the fluid from the fluid supply source and the state of the control valve. Although a lateral load is applied to the core rod 20F due to the bulging of the rubber mold 33, the load is received by the upper punch 2 to prevent the core rod 20F from being bent or bent.
[0018]
Next, a specific operation for forming the intermediate relief portion in the bearing material 10 by the groove processing apparatus will be described.
First, as shown in FIG. 1A, the bearing material 10 is fitted to the large diameter portion 21 of the core rod 20 </ b> F and supported on the lower punch 3. In this set state, as shown in FIG. 2A, the bearing material 10 is surrounded by the rubber mold 33, and the large-diameter portion 21 is arranged in the axial center of the bearing material 10. The inner diameter of the bearing material 10 is slightly larger than the large-diameter portion 21 of the core rod 20F, and there is a gap between them, or there is almost no gap between them, or it is almost the same as the large-diameter portion 21 or the large-diameter portion 21. It may be any dimension that is smaller than that of an interference fit. If there is no gap or an interference fit, the bearing material 10 is pushed down by the upper punch 2 and fitted into the large diameter portion 21. In any case, a gap exists between the inner peripheral surface of the bearing material 10 and the small diameter portion 22 of the core rod 20F.
[0019]
Next, as shown in FIG. 1B, the upper punch 2 is lowered to pivotally support the small diameter portion 22 at the upper end of the core rod 20 </ b> F, and the bearing material 10 is pressed by the upper punch 2. Then, as shown in FIG. 2 (b), a fluid is supplied to one pressure chamber 36a to increase the pressure and bulge the rubber mold 33 at that portion, while the pressure chamber 36e facing the pressure chamber 36a. The pressure in the pressure chambers 36b to 36d and 36f to 36h between the pressure chambers 36a and 36e is inclined so as to gradually decrease from the pressure chamber 36a toward the pressure chamber 36e. Then, the bearing material 10 is held in an eccentric state with respect to the axis of the core rod 20F by the rubber mold 33, and at the same time, the outer peripheral surface of the bearing material 10 is pressed by the most bulged portion of the rubber mold 33. The inner peripheral surface of the pressed bearing material 10 at the pressed portion is in close contact with the outer peripheral surface of the core rod 20F, and further receives pressure so that the large-diameter portion 21 is indented into the inner peripheral surface, and the upper and lower inner surfaces thereof are engraved. The peripheral surface is pressed by the small diameter portion 22.
[0020]
Next, the pressure chamber to be high pressure is sequentially moved in the circumferential direction from the pressure chamber 36a, and the low pressure chamber is moved in the same circumferential direction from the pressure chamber 36e, and further, between the high pressure and low pressure chambers. Engraving of the large diameter portion 21 on the inner peripheral surface of the bearing material 10 due to the bulging of a part of the rubber mold 33 every time one pressure chamber is increased in pressure while gradually performing the operation of inclining the pressure in the pressure chamber. I do. FIG. 1C shows a state in which the pressure chamber 36e is at a high pressure and the pressure chamber 36a facing the pressure chamber 36e is at a low pressure. At this time, the large-diameter portion 21 is engraved on the inner peripheral surface of the bearing material 10 at the portion corresponding to the pressure chamber 36e, while the middle escape portion (inner peripheral groove) 11 is already corresponding to the pressure chamber 36a on the low-pressure side. The inner peripheral surface of the bearing material 10 on which a part of is formed is separated from the core rod 20F. When such an operation is performed once, the large-diameter portion 21 of the core rod 20F is transferred to the inner peripheral surface of the bearing material 10, the intermediate escape portion 11 is formed over the entire periphery, and the bearing surfaces 12 are formed on both sides thereof. The
[0021]
In addition, what is necessary is just to perform the frequency | count determined by experiment, when the escape part 11 does not become a desired shape or depth even if the operation which raises pressure chambers 36a-36h one by one is performed once. In this case, the small diameter portion 22 of the core rod 20F is pressed against the inner peripheral surface of the bearing material 10. However, it is also possible to form the middle escape portion 11 by causing only the large diameter portion 21 to act on the inner peripheral surface. Yes, whether or not the small-diameter portion 11 acts on the inner peripheral surface may be appropriately selected according to the purpose.
[0022]
When the above operation for sequentially increasing the pressure in the circumferential direction of the pressure chambers 36a to 36h is performed to form the intermediate escape portion 11 on the inner peripheral surface of the bearing material 10, the pressure chambers 36a to 36h are formed as shown in FIG. The bearing material 10 is held by the rubber mold 33. In this state, the bearing material 10 is coaxial with the core rod 20F, and the inner diameter of the bearing surface 12 on the inner circumferential surface is equal to or larger than the outer diameter of the large-diameter portion 21 of the core rod 20F. For this reason, as shown in FIG.1 (d), the core rod 20F can be extracted from the bearing raw material 10, without the large diameter part 21 interfering with the bearing surface 12. FIG. After the core rod 20F is lowered and the core rod 20F is extracted from the bearing material 10 as shown in the figure, the pressure of the pressure chambers 36a to 36h is reduced to increase the diameter of the rubber mold 33 so that it is separated from the bearing material 10. The material 10 is released. Then, the upper punch 2 is raised and the bearing material 10 is taken out.
[0023]
FIG. 3A shows a half-section of the bearing 10F obtained as described above, and bearing surfaces 12 are formed at both ends on the inner peripheral surface of the bearing 10F, and a middle relief portion therebetween. 11 is formed. The bearing 10F is suitable as a bearing for a rotating shaft that rotates at a relatively high speed, such as a spindle motor. The bearing 10F is sized on the bearing surface 12, the outer peripheral surface, and the end surface as necessary. When the housing is mounted by press fitting or the like, the shaping core rod is usually inserted into the shaft hole of the bearing 10F, so that the bearing surface 12 is sized.
[0024]
According to the method for manufacturing a sintered bearing using the above-described apparatus, the inner diameter of the bearing surface 12 of the bearing material 10 is reduced to the core rod 20F at the stage where the compression operation by the rubber mold 33 is completed over the entire inner peripheral surface of the bearing material 10. Therefore, the core rod 20 </ b> F can be extracted from the bearing material 10 without the large diameter portion 21 interfering with the bearing surface 12. Therefore, even if the bearing material 10 has little or no springback, the core rod 20F can be reliably extracted, and the intermediate escape portion 11 can be reliably formed in such a bearing material 10. it can. Moreover, the escape part 11 can be made deeper.
[0025]
In the above groove processing apparatus, the core rod 20F is lowered to extract the core rod 20F from the bearing material 10. However, the core rod 20F is fixed by moving the upper and lower punches 2 and 3 to move the core rod 20F to the bearing material. The form extracted from 10 may be sufficient. Moreover, although the axial direction of the core rod 20F is a vertical type extending vertically, it can be a horizontal type. Further, in the above embodiment, the number of pressure chambers is eight, but the number is arbitrary as long as the bearing material 10 can be accurately compressed.
[0026]
The core rod 20F was provided with the large-diameter portion 21 for forming the middle escape portion 11, but instead of the core rod 20F, by applying a core rod for forming a dynamic pressure groove to the device, A bearing having a dynamic pressure groove on the inner peripheral surface can be manufactured.
[0027]
FIGS. 4A to 4D illustrate such a core rod.
A plurality of substantially V-shaped grooves (small diameter portions) 23 converging in the circumferential direction are formed in a herringbone pattern on the outer peripheral surface of the core rod 20A shown in FIG. The depth of each groove 23 is uniform and formed at equal intervals, and between each groove 23 is a protrusion (large diameter portion) 24 whose outer diameter is equal to the outer diameter of the core rod 20A. When the inner peripheral surface of the bearing material 10 is processed with the core rod 20A in the same manner as in FIG. 1, a bearing 10A shown in FIG. 3B is manufactured. A groove 23 of the core rod 20A is engraved on the inner peripheral surface of the bearing 10A, thereby forming a ridge 13 with the inner peripheral surface serving as a bearing surface 13a. A dynamic pressure groove 14 is formed.
[0028]
Projections 24 are formed in a herringbone pattern on the outer peripheral surface of the core rod 20B shown in FIG. 4B, and the grooves 23 between the projections 24 are equal to the outer diameter of the core rod 20B. According to the core rod 20 </ b> B, the dynamic pressure groove is formed by the ridge 24, and the bearing surface is formed by the groove 23. In this case, the end of the dynamic pressure groove is closed.
[0029]
In the core rod 20C shown in FIG. 4C, the groove 21 and the protrusion 22 shown in FIG. 3A are formed at two spaced locations corresponding to both ends of the bearing to be manufactured. A middle relief portion is formed by the large-diameter portion 25 therebetween. A bearing 10C shown in FIG. 3C is manufactured by the core rod 20C. The bearing 10C is formed with ridges 13, bearing surfaces 13a, and dynamic pressure grooves 14 at both ends, respectively, and a middle escape portion 11 is formed therebetween. In this case, the diameter of the middle escape portion 11 and the dynamic pressure groove 14 are the same.
[0030]
In the core rod 20D shown in FIG. 4 (d), the outer diameters of the ridges 24 forming the dynamic pressure grooves and the large-diameter portions 25 forming the middle escape portions are equal, and the outer diameters of the grooves 23 and the core rod 20D are equal. The dynamic pressure groove formed by the core rod 20D has a closed end.
[0031]
When the dynamic pressure grooves are formed on the inner peripheral surface of the bearing material by the core rods 20A to 20D, the ridges 24 and the large-diameter portions 25 may only be engraved on the inner peripheral surface of the bearing material. The outer peripheral surface with a small diameter and the bottom of the groove 23 may be pressed against the inner peripheral surface. These production methods are appropriately selected according to the purpose.
[0032]
FIGS. 3D and 3E show other forms of dynamic pressure grooves formed in the bearing.
A plurality of fine V-shaped convex strips 13 that converge in the circumferential direction are formed on the inner peripheral surface of the bearing 10D in FIG. 3D, and the inner peripheral surface of these convex strips 13 is a bearing surface 13a. is there. A groove between the ridges 13 is a dynamic pressure groove 14. Spiral ridges 13 are formed over the entire inner circumferential surface of the bearing 10E in FIG. 3E, and the inner circumferential surface of these ridges 13 is a bearing surface 13a. A spiral groove between the ridges 13 is a dynamic pressure groove 14.
[0033]
Next, another embodiment of the present invention will be described with reference to FIGS.
FIG. 5 shows a grooving apparatus according to this embodiment, and reference numeral 41 in the drawing is a base. An upper ram 42 that can be raised and lowered is disposed above the base 41, and a lower ram 43 that can be raised and lowered is disposed opposite to the upper ram 42. A cylindrical upper punch (core rod shaft support member) 44 is fixed to the upper ram 42, and a core rod 20 </ b> F is fixed to the lower ram 43. The core rod 20F is the same as that of the previous embodiment, and includes a large diameter portion 21 and a small diameter portion 22. The core rod 20F passes through the base 41 until the large-diameter portion 21 is arranged on the base 41, and the upper punch 44 slides and fits into the small-diameter portion 22 on the upper end side, whereby the core rod 20F Is pivotally supported to withstand lateral loads. Reference numeral 10 denotes a cylindrical bearing material made of a sintered body. The bearing material 10 is fitted to the large diameter portion 21 of the core rod 20F and supported on the base 41.
[0034]
A compression mechanism 50 is provided on the base 1 to form a middle relief portion on the inner peripheral surface of the bearing material 10. As shown in FIG. 6, the compression mechanism 50 is arranged radially with the axis of the core rod 20F as the center, and a plurality of (in this case, eight) horizontal punches 51a that are movable forward and backward with respect to the axis. To 51h and an actuator (not shown) for driving these lateral punches 51a to 51h. As can be seen from FIG. 6B, the front end portions of the horizontal punches 51 a to 51 h are formed in a tapered shape so that adjacent ones do not interfere with each other during forward movement, and the front end surface thereof is the outer periphery of the bearing material 10. It is formed in the circular arc surface which followed the surface.
[0035]
According to the compression mechanism 30, when the lateral punches 51a to 51h are advanced, the lateral punches 51a to 51h are fitted to the large diameter portion 21 of the core rod 20F and are supported on the base 41 and the outer peripheral surface of the bearing material 10. Press. As a result, the bearing material 10 is compressed in the radial direction, the inner peripheral surface thereof is in close contact with the outer peripheral surface of the core rod 20F, and the large-diameter portion 21 is stamped on the inner peripheral surface. When the horizontal punches 51a to 51h are retracted, the horizontal punches 51a to 51h are separated from the bearing material 10 and the bearing material 10 is released. Further, by appropriately determining the amount of advance of the horizontal punches 51a to 51h, the horizontal punches 51a to 51h can contact the bearing material 10 with an appropriate pressure, and the bearing material 10 can be held. Such an operation is performed by a control circuit (not shown) appropriately controlling an actuator that is a drive source of the lateral punches 51a to 51h.
[0036]
Next, a procedure for forming the middle relief portion on the inner peripheral surface of the bearing material 10 by the groove processing apparatus will be described.
First, as shown in FIG. 6 (a), the horizontal punches 51a to 51h are moved backward to fit the bearing material 10 to the large diameter portion 21 of the core rod 20F, and then, as shown in FIG. Is lowered to pivotally support the small diameter portion 22 at the upper end of the core rod 20F, the bearing material 10 is pressed by the upper punch 44, and the lateral punches 51a to 51h are advanced to hold the bearing material 10.
[0037]
Next, one horizontal punch 51a is further advanced, while the horizontal punch 51e facing the horizontal punch 51a is slightly retracted, and the horizontal punches 51b to 51d and 51f to 51h advance between the horizontal punches 51a and 51e. The amount is inclined so as to gradually decrease from the lateral punch 51a toward the lateral punch 51e. Then, the bearing material 10 is held in an eccentric state with respect to the axis of the core rod 20F by the horizontal punches 51a to 51h, and at the same time, the outer peripheral surface of the bearing material 10 is pressed by the most advanced horizontal punch 51a. The inner peripheral surface of the pressed bearing material 10 is in close contact with the outer peripheral surface of the core rod 20F, and further receives pressure so that the large-diameter portion 21 is recessed and stamped on the inner peripheral surface. The peripheral surface is pressed by the small diameter portion 22.
[0038]
Next, the lateral punch to be most advanced is sequentially moved in the circumferential direction from the lateral punch 51a, and the lateral punch to be most retracted is moved in the same circumferential direction from the lateral punch 51e. The large diameter portion 21 is marked on the inner peripheral surface of the bearing material 10 each time one horizontal punch is advanced while gently performing the tilting operation. When such an operation is performed once, the large-diameter portion 21 of the core rod 20F is transferred to the inner peripheral surface of the bearing material 10, and the intermediate escape portion is formed over the entire periphery, and the bearing surfaces are formed on both sides thereof.
[0039]
When the intermediate punching portion is formed on the inner peripheral surface of the bearing material 10 by performing the above-described operation of sequentially moving the lateral punches 51a to 51h in the circumferential direction, the amount of advancement of each lateral punch 51a to 51h is made equal to each other. Hold by the horizontal punches 51a-51h. In this state, the bearing material 10 is coaxial with the core rod 20F, and the inner diameter of the bearing surface 12 on the inner circumferential surface is equal to or larger than the outer diameter of the large-diameter portion 21 of the core rod 20F. For this reason, the core rod 20 </ b> F can be extracted from the bearing material 10 without the large diameter portion 21 interfering with the bearing surface 12. Therefore, the core rod 20F is lowered and the core rod 20F is extracted from the bearing material 10. Thereafter, the lateral punches 51a to 51h are moved backward to release the bearing material 10, and the upper punch 44 is raised to remove the bearing material 10. .
[0040]
Even if the sintered bearing manufacturing method using the above-described apparatus is used, the same effect as the previous embodiment, that is, even if the bearing material 10 has little or no springback, The core rod 20F can be reliably extracted without interference, and the intermediate relief portion can be reliably formed in such a bearing material 10.
[0041]
In addition, although this embodiment was a form which forms a middle escape part, it can of course be formed by applying each core rod 20A-20D shown in FIG. 4 instead of the core rod 20F, and thereby forming a dynamic pressure groove. Further, in the above embodiment, the number of horizontal punches is eight, but the number is arbitrary as long as the bearing material 10 can be accurately compressed.
[0042]
【The invention's effect】
As described above, according to the present invention, the core rod for forming the inner circumferential groove can be reliably extracted from the bearing material with little or no springback. There exists an effect that a groove | channel can be formed reliably.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing steps of manufacturing a bearing with an inner circumferential groove by a groove processing apparatus according to an embodiment of the present invention in the order of (a) to (d).
FIGS. 2A to 2C are cross-sectional views showing a grooving apparatus according to an embodiment of the present invention according to circumstances.
FIGS. 3A to 3E are half sectional views of a bearing showing various forms of inner circumferential grooves formed by a groove machining apparatus according to an embodiment of the present invention.
4 (a) to 4 (d) are side views showing various forms of a core rod according to the present invention.
FIG. 5 is a longitudinal sectional view showing a groove processing apparatus according to another embodiment of the present invention.
FIGS. 6A and 6B are cross-sectional views showing a grooving apparatus according to another embodiment of the present invention according to circumstances.
[Explanation of symbols]
2,44 ... Upper punch (core rod shaft support member)
10 ... Bearing material
10A, 10C, 10D, 10E, 10F ... Bearing
11 ... Middle escape part (inner circumferential groove)
12, 13a ... Bearing surface
14 ... Dynamic pressure groove (inner circumferential groove)
20A, 20B, 20C, 20D, 20F ... Core rod
21 ... large diameter part
22 ... Small diameter part
23 ... Groove (small diameter part)
24 ... ridge (large diameter part)
30 ... Rubber press mechanism (compression mechanism)
33 ... Rubber mold (elastic body)
36a-36h ... Pressure chamber
50 ... Compression mechanism
51a-51h ... Horizontal punch

Claims (4)

A core rod having a small diameter part for forming the bearing surface and a large diameter part for forming the inner circumferential groove is inserted into a cylindrical bearing material made of a sintered body,
Next, the bearing material is compressed while being eccentric in the radial direction by pressing a part of the outer peripheral surface of the bearing material toward the axis of the core rod, and a part of the large-diameter portion is imprinted on the inner peripheral surface. The operation is sequentially performed in the circumferential direction over the entire circumference of the bearing material while releasing the compression operation after the operation, thereby transferring at least the large diameter portion of the core rod to the inner circumferential surface of the bearing material,
Thereafter, a core rod is relatively extracted from the bearing material, and a method for manufacturing a sintered bearing with an inner circumferential groove is provided.   The method for manufacturing a sintered bearing with an inner circumferential groove according to claim 1, wherein the inner circumferential groove is a dynamic pressure groove or a middle escape portion having a larger diameter than the bearing surface. A core rod having a small-diameter portion for forming a bearing surface and a large-diameter portion for forming an inner circumferential groove, and inserted into a cylindrical bearing material made of a sintered body;
A core rod support member for supporting the core rod;
A cylindrical elastic body arranged to surround the bearing material inserted into the core rod, and a plurality of pressure chambers divided and defined in the circumferential direction on the outer peripheral side of the elastic body and supplied with fluid. A compression mechanism for holding, compressing or releasing the outer peripheral surface of the bearing material by part of the elastic body corresponding to each pressure chamber expanding and contracting with respect to the axis of the core rod according to the fluid pressure in the pressure chamber;
Control means for controlling the fluid pressure in the pressure chamber of the compression mechanism,
The control means controls the fluid pressure in the pressure chamber so that compression and release operations on the outer circumferential surface of the bearing member by a part of the elastic body are sequentially performed in the circumferential direction over the entire circumferential area of the bearing member. A groove processing device for a sintered bearing with an inner circumferential groove, characterized by controlling . A core rod having a small-diameter portion for forming a bearing surface and a large-diameter portion for forming an inner circumferential groove, and inserted into a cylindrical bearing material made of a sintered body;
A core rod support member for supporting the core rod;
A horizontal punch comprising a plurality of horizontal punches arranged radially around the bearing material inserted into the core rod and capable of moving back and forth with respect to the axis of the core rod, and a drive source for moving the horizontal punch forward and backward. A compression mechanism for holding, compressing or releasing the outer peripheral surface of the bearing material in accordance with the advancement and retraction of the
Control means for controlling the amount of advance and retreat of the lateral punch of this compression mechanism,
The control means controls the drive source so that compression and release operations on the outer peripheral surface of the bearing member by the lateral punch are sequentially performed in the circumferential direction over the entire peripheral area of the bearing member. Groove processing machine for sintered bearings with inner grooves.

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