JP2011074953A - Sintered bearing, sizing device for sintered body, and sizing method for sintered bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sintered body securing high dimension accuracy while having an outer circumference shape in which a cross section shape is a non true circle shape by applying accurate sizing even on the sintered body for a sintered bearing or the like having the outer circumference shape. <P>SOLUTION: This sizing device 1 for the sintered bearing includes a die 3 having a holding hole 2 holding the sintered bearing W having the outer circumference shape in which the cross section shape is a non true circle shape, a core shaft 4 inserted in an inner circumference surface of the sintered bearing W held in the holding hole 2, and an upper punch 5 and a lower punch 6 pressing the sintered bearing W held in the holding hole 2 from an up-and-down direction. The die 3 includes a fixed part 7 and a movable pressing part 8. The movable pressing part 8 forms a holding hole 2 and is divided into a plurality of parts in a circumference direction. The holding hole 2 is expanded and contracted by movement of each divided parts. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to sizing of a sintered body such as a sintered bearing.

  For example, as is well known, cylindrical bearings are widely used as sintered bearings, and the inner peripheral surface thereof is used as a bearing surface to support the radial load of the shaft. This type of sintered bearing is manufactured by compacting a metal powder powder and then sintering. Usually, in order to obtain a predetermined dimensional accuracy, Is sized using a sizing device.

  Such a sizing device generally includes a die, a core shaft, an upper punch, and a lower punch, and each component has the following relationship. That is, the die has a circular accommodation hole that accommodates the sintered bearing, and a cylindrical core shaft is arranged coaxially with the accommodation hole of the die. Each of the upper punch and the lower punch has a cylindrical shape, and can be freely inserted and removed between the die and the core shaft in the vertical direction.

  Then, the inner diameter of the die receiving hole is set slightly larger than the outer diameter of the sintered bearing before sizing, and the sintered bearing is sized as follows.

  That is, the sintered bearing is accommodated in the die receiving hole, the core shaft is inserted into the inner periphery of the sintered bearing, the upper punch is lowered, and the sintered bearing is pressed by the upper punch and the lower punch. Compress the vertical dimension to size the vertical dimension. At this time, the sintered bearing compressed in the vertical direction is deformed in the radial direction and brought into close contact with the die and the core shaft, and the inner and outer diameter dimensions of the sintered bearing are sized (see, for example, Patent Document 1 below).

Japanese Patent Laid-Open No. 2-149605

  By the way, for the purpose of improving maintainability, for example, a sintered bearing having a U-shaped cross section perpendicular to the axis may be used so that it can be easily removed from the axis. However, it is necessary to perform accurate sizing similarly to the above-described cylindrical sintered bearing.

  However, the above Patent Document 1 does not describe any method for sizing a sintered bearing having a U-shaped cross section perpendicular to the axis. Moreover, even if it is possible to apply the technique disclosed in Patent Document 1 to the sizing of a U-shaped sintered bearing, the sizing of the inner and outer peripheral surfaces of the sintered bearing is performed by the die and the core shaft. It is difficult to do accurately. This is because even if the sintered bearing is compressed in the vertical direction with the upper punch and the lower punch, deformation in the direction perpendicular to the axial direction due to the compression hardly occurs, resulting in insufficient sizing. This is because a certain part is generated.

  The above problems are largely caused by the complexity of the outer peripheral surface shape of the sintered bearing to be sized. Therefore, for example, the above problem may occur when an outer peripheral surface shape is formed by a plurality of planes (specifically, when the outer peripheral surface shape is a polygon such as a quadrangle), or by combining a plane and a curved surface. When the outer peripheral surface shape is formed (specifically, the outer peripheral surface shape is a U-shape or an oval shape, which will be described later), or the outer peripheral surface shape is formed by combining a plurality of partial cylindrical surfaces having different curvatures. For example, a sintered body having an outer peripheral surface shape with a non-circular cross-sectional shape can similarly occur.

  In view of the above situation, the object of the present invention is to perform highly accurate sizing on a sintered body such as a sintered bearing having a non-circular shape in cross-sectional shape, so that the shape of the outer peripheral surface is obtained. An object of the present invention is to provide a sintered body having high dimensional accuracy while having it.

  The sintered bearing according to the present invention, which was created to solve the above problems, is a sintered bearing having an outer peripheral surface shape having a non-circular cross-sectional shape, and the outer peripheral surface shape is circumferential. It is characterized in that it is formed by connecting the processed surfaces sized by a press surface divided into a plurality of portions.

  According to such a configuration, the outer peripheral surface shape of the sintered bearing having a non-circular cross-sectional shape is formed by connecting the processed surfaces sized by the press surface divided into a plurality in the circumferential direction. Therefore, even if the outer peripheral surface shape of the sintered bearing becomes complicated by becoming a non-circular shape, the outer peripheral surface shape of the sintered bearing that is sized by the divided press surfaces can be simplified. That is, by simplifying the shape of the outer peripheral surface of the sintered bearing in this way, it becomes possible to apply a pressing force directly and evenly to the outer peripheral surface of the sintered bearing by the individual press surfaces. It becomes difficult to generate a portion where the pressing force applied to the inner and outer peripheral surfaces is insufficient. Therefore, even if it is a sintered bearing having an outer peripheral surface shape with a non-circular cross-sectional shape, if the outer peripheral surface shape is formed by connecting the processed surfaces sized by the press surfaces divided as described above. High dimensional accuracy can be ensured.

  In the above configuration, in the shape of the outer peripheral surface, a linear mark following the division position of the press surface may be formed between the processing surfaces connected to each other.

  In this case, if the sintered bearing which is a finished product is seen, it can be easily recognized that the sizing of the outer peripheral surface is made by the divided press surface.

  In the above configuration, the outer peripheral surface shape may be U-shaped.

  In the above configuration, the sintered bearing is a sintered bearing having an outer peripheral surface shape having a non-circular cross-sectional shape, and the surface opening ratio of the inner peripheral surface is not less than 5% and less than 50%. The surface opening ratio is 20% or more and 50% or less, and the surface opening ratio of the outer peripheral surface is larger than the surface opening ratio of the inner peripheral surface. In addition, the surface opening ratio here means the ratio of the sum total (total area) of the area of each opening per unit area, and is measured under the following conditions. That is, as a measuring instrument, metal microscope: Nikon ECLIPSS ME600, digital camera: Nikon DXM1200, photography software: Nikon ACT-1 ver. 1 and image processing software: QUICK GRAIN manufactured by Innotek is used, the shutter speed at the time of photographing is 0.5 seconds, and the binarization threshold value is 235.

  In this way, the surface open area ratio of the inner and outer peripheral surfaces of the sintered bearing is approximately the same as that of the sintered bearing having an inner and outer peripheral surface shape whose cross-sectional shape is a perfect circle. In addition, since the surface aperture ratio of the outer peripheral surface is set to be larger than the surface aperture ratio of the inner peripheral surface, the following advantages are enjoyed when used in a state of being impregnated with lubricating oil. be able to. That is, if the surface opening ratio on the outer peripheral surface side is larger than the surface opening ratio on the inner peripheral surface side, the space in which the lubricating oil can be held inside increases on the outer peripheral surface side. An appropriate amount of lubricating oil is sequentially supplied from the outer peripheral surface side holding a large amount of lubricating oil to the inner peripheral surface side having a smaller surface opening ratio than the outer peripheral surface side, thereby realizing stable sliding characteristics. . In addition, if the surface area ratio on the inner peripheral surface side is larger than the surface area ratio on the outer peripheral surface side, the space for retaining the lubricant is formed mainly on the inner peripheral surface side. In addition, the lubricating oil is excessively supplied, and it becomes difficult to realize stable sliding characteristics.

  A sizing apparatus for a sintered body according to the present invention, which has been created to solve the above-mentioned problems, includes a die having an accommodation hole that accommodates a sintered body having an outer peripheral surface shape having a non-circular cross-sectional shape; A sintered body comprising a core shaft inserted into an inner peripheral surface of the sintered body accommodated in the accommodation hole, and an upper punch and a lower punch for pressing the sintered body accommodated in the accommodation hole from above and below. The die includes a fixed portion and a movable pressing portion, and the movable pressing portion forms the receiving hole and is divided into a plurality of portions in a circumferential direction. It is characterized by being configured to expand and contract the accommodation hole.

  According to such a configuration, the outer peripheral surface of the sintered body can be pressed toward the core shaft side by moving the movable pressing portion of the die divided into a plurality in the circumferential direction and reducing the accommodation hole. it can. Therefore, as compared with the conventional case, the sintered body is deformed so that the inner and outer peripheral surfaces of the sintered body are in close contact with the die and the core shaft only by compressing the sintered body in the vertical direction by the upper punch and the lower punch. A pressing force is directly and evenly applied to the outer peripheral surface of the. Therefore, it becomes difficult to generate a portion where the pressing force applied to the inner and outer peripheral surfaces of the sintered body becomes insufficient, and as a result, highly accurate sizing can be performed.

  In addition, after sizing, the contact state between the outer peripheral surface of the sintered body after sizing and the movable pressing portion is increased by moving each movable pressing portion divided into a plurality in the circumferential direction and expanding the accommodation hole. It can also be released easily. Therefore, in this state, if the sintered body after sizing is taken out from the housing hole of the die, no galling occurs between the housing hole and the sintered body, so that the sintered body is maintained while maintaining high-precision sizing. Can be taken out.

  In the above configuration, the fixed portion of the die has a tapered surface that is inclined downward toward the core axis, and the movable pressing portion moves up and down along the tapered surface. It is preferable that the accommodation hole is adapted to expand and contract.

  In this way, since the accommodation hole is expanded and contracted simply by moving the movable pressing portion up and down along the tapered surface, it becomes possible to easily and reliably execute the sizing of the sintered body.

  In the above-described configuration, an elastic member that elastically supports the movable pressing portion with respect to the fixed portion from below is provided, and the movable pressing portion moves downward against the elastic force of the elastic member, whereby the accommodation is performed. It is preferable that the hole be reduced.

  In this way, if the force that moves the movable pressing portion downward along the tapered surface is released, the movable pressing portion automatically moves upward along the tapered surface by the elastic force of the elastic member. The pressing part is separated from the outer peripheral surface of the sintered body. Therefore, the sintered body after sizing can be easily taken out from the accommodation hole of the die.

  In the above configuration, it is preferable that the downward movement of the movable pressing portion is performed by pressing the movable pressing member downward with the upper punch.

  In this way, all the pressing force applied to the sintered body can be adjusted simply by controlling the stroke amount of the upper punch in the vertical direction. It is extremely advantageous also in applying.

  Said structure WHEREIN: You may make it the said upper punch have a 1st press surface which presses the upper surface of the said sintered compact, and a 2nd press surface which presses the upper surface of the said movable press part.

  If it does in this way, the surface which presses the upper surface of a movable press part among the press surfaces of an upper punch, and the surface which presses the upper surface of a sintered compact can be comprised by a separate surface. That is, when the required surface properties are different between the surface pressing the upper surface of the movable pressing portion and the surface pressing the upper surface of the sintered body (usually, the surface pressing the upper surface of the sintered body is more required). Therefore, it is preferable that each surface to be provided with an excessive surface property can be provided with an appropriate surface property.

  A method for sizing a sintered bearing according to the present invention, which has been devised to solve the above problems, is a method for sizing a sintered bearing having an outer peripheral surface shape with a non-circular cross-sectional shape, The outer peripheral surface shape is characterized by sizing by a press surface divided into a plurality in the circumferential direction.

  According to such a method, the outer peripheral surface shape of the sintered bearing having a non-circular cross-sectional shape is sized by the press surface divided into a plurality in the circumferential direction. For this reason, even if the outer peripheral surface shape of the sintered bearing becomes non-circular and complicated, the outer peripheral surface shape of the sintered bearing can be simplified by the individual divided press surfaces. By simplifying the outer peripheral surface shape of the sintered bearing in this way, it becomes possible to apply a pressing force directly and evenly to the outer peripheral surface of the sintered bearing by the individual press surfaces. It is difficult to generate a portion where the pressing force applied to the peripheral surface is insufficient. Therefore, even with a sintered bearing having a non-circular outer peripheral surface shape in cross-sectional shape, highly accurate sizing can be performed by the outer peripheral surface shape, and high dimensional accuracy can be ensured. .

  As described above, according to the present invention, it is possible to perform highly accurate sizing on a sintered body such as a sintered bearing having an outer peripheral surface shape with a non-circular cross-sectional shape. It is possible to provide a sintered body having high shape accuracy while having a shape.

(A) is sectional drawing which shows the whole structure of the sizing apparatus which concerns on one Embodiment of this invention, (b) is AA sectional drawing of (a). It is a figure explaining the sizing process of the sintered bearing using the sizing apparatus which concerns on this embodiment. (A) is a figure explaining the sizing process of the sintered bearing which uses the sizing apparatus concerning this embodiment, (b) is BB sectional drawing of (a). It is a figure explaining the sizing process of the sintered bearing using the sizing apparatus which concerns on this embodiment. It is a figure explaining the sizing process of the sintered bearing using the sizing apparatus which concerns on this embodiment. It is a perspective view which shows the usage example of the sintered bearing sized by the sizing apparatus which concerns on this embodiment. (A) is a figure which shows the modification of the sizing apparatus which concerns on this embodiment, (b) is a figure which shows the state which is actually sizing a sintered bearing using the sizing apparatus. .

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  1A and 1B illustrate the overall configuration of a sizing device according to an embodiment of the present invention. As shown in the figure, the sizing device 1 is inserted into a die 3 having a housing hole 2 for housing a sintered bearing W as a sintered body, and an inner peripheral surface of the sintered bearing W housed in the housing hole 2. The core shaft 4 that moves up and down removably, the upper punch 5 that moves up and down between the die 3 and the core shaft 4, and the up and down movement between the die 3 and the core shaft 4 move up and down. The lower punch 6 is provided. In this embodiment, as the sintered bearing W, as shown in FIG. 1B, an example in which the cross section perpendicular to the axis is a U-shape including a straight portion Wa and an arc portion Wb will be described.

  The die 3 includes a fixed portion 7 and a movable pressing portion 8. The movable pressing portion 8 forms the receiving hole 2 and is divided into a plurality of portions in the circumferential direction, and is configured to expand and contract the receiving hole 2 by moving each divided portion. More specifically, as shown in FIG. 1B, the movable pressing portion 8 is divided for each portion where the shape change mode of the outer peripheral surface of the sintered bearing W is different. That is, the movable pressing portion 8 is divided into a portion surrounding the outer peripheral surface of the linear portion Wa of the sintered bearing W and a portion surrounding the outer peripheral surface of the arc portion Wb of the sintered bearing W. The inner peripheral surface of the divided movable pressing portion 8 has a shape that the outer peripheral surface of the sintered bearing W after sizing should take, that is, the outer periphery of each of the linear portion Wa and the arc portion Wb of the sintered bearing W after sizing. The surface matches the shape to be taken. In the illustrated example, the movable pressing portion 8 is further divided into two at a portion surrounding the outer peripheral surface of the arc portion Wb of the sintered bearing W. In other words, if the movable pressing portion 8 is divided at least for each portion where the shape change mode of the outer peripheral surface of the sintered bearing W is different, the shape change mode of the outer peripheral surface is within the same region. It may be finely divided.

  Each movable pressing portion 8 is slidable in the vertical direction along a tapered surface 7 a formed on the fixed portion 7 of the die 3. Since the taper surface 7a corresponding to each movable pressing portion 8 is inclined downward in a direction approaching the core shaft 4, the accommodation hole 2 is enlarged when the movable pressing portion 8 is raised along the taper surface 7a. When the movable pressing portion 8 is lowered along the tapered surface 7a, the accommodation hole 2 is reduced and the distance D from the core shaft 4 is reduced. .

  Each movable pressing portion 8 is elastically supported from below by a damper mechanism 9 as an elastic member. That is, the movable pressing portion 8 is positioned at the upper end portion of the tapered surface 7a and is not positioned in the direction of descending along the tapered surface 7a, as shown in FIG. The distance D between the two is maximized. In the example shown in FIG. 1A, the upper surface of each movable pressing portion 8 is positioned on the same plane as the upper surface of the fixed portion 7 in a state where no force is applied from the outside.

  The outer peripheral surface of the core shaft 4 matches the shape that the inner peripheral surface of the sintered bearing W after sizing should take. That is, in this embodiment, the outer peripheral surface of the core shaft 4 has a shape that matches the respective inner peripheral surfaces of the linear portion Wa and the arc portion Wb of the sintered bearing W after sizing.

  The upper punch 5 has a through hole 5a through which the core shaft 4 is inserted. On the lower surface of the upper punch 5, a pressing surface 5b having a height difference in the vertical direction is formed. A high portion surface (first pressing surface) 5b1 of the pressing surface 5b protruding downward has a U shape so that the upper surface of the sintered bearing W can be pressed. On the other hand, the lower surface (second pressing surface) 5b2 of the pressing surface 5b retracted upward from the high surface 5b1 is in contact with the upper surface of the movable pressing portion 8 of the die 3, and the movable pressing portion 8 is moved to the damper mechanism 9. It pushes in the downward direction along the tapered surface 7a against the elastic force.

  The lower punch 6 has a through hole 6a through which the core shaft 4 is inserted. On the upper surface of the lower punch 6, a pressing surface 6b having a U-shape capable of pressing the lower surface of the sintered bearing W is formed.

  In this embodiment, in the state shown in FIGS. 1A and 1B, there is a gap between the inner peripheral surface of the divided movable pressing portion 8 and the outer peripheral surface of the sintered bearing W before sizing. Is formed. Further, a gap is also formed between the movable pressing portions 8 adjacent along the outer peripheral surface (circumferential direction) of the sintered bearing W.

  In addition, the sintered bearing W before sizing protrudes to the outside of the pressing surface 6b of the lower punch 6 (on the movable pressing portion 8 side of the die 3) while being placed on the pressing surface 6b of the lower punch 6. Thus, the dimension shape of the pressing surface 6b of the lower punch 6 is defined. The same applies to the high surface 5b1 of the upper punch 5 having the same shape as the pressing surface 6b of the lower punch 6. That is, when the upper surface of the sintered bearing W before sizing is brought into contact with the high portion surface 5b1 of the upper punch 5, the sintered bearing W protrudes outside the high portion surface 5b1.

  Next, a method for sizing the sintered bearing W using the sizing device 1 configured as described above will be described.

  First, as shown in FIG. 1A, the lower surface of the sintered bearing W is supported by the lower punch 6, and the core shaft 4 is inserted into the inner peripheral surface of the sintered bearing W. At this time, a gap is formed between the movable pressing portion 8 of the die 3 and the outer peripheral surface of the sintered bearing W as shown in FIG. Since it is not necessary to accommodate in the accommodation hole 2 while press-fitting, the sintered bearing W can be easily set on the lower punch 6.

  When the upper punch 5 is lowered from the state shown in FIGS. 1A and 1B, the lower surface 5 b 2 of the pressing surface 5 b of the upper punch 5 is placed on the upper surface of the movable pressing portion 8 as shown in FIG. Abut. At this time, of the pressing surface 5 b of the upper punch 5, the high portion surface 5 b 1 protruding downward from the low portion surface 5 b 2 is inserted between the movable pressing portion 8 and the core shaft 4.

  Thereafter, when the upper punch 5 is further lowered, the movable pressing portion 8 is pushed in the direction of lowering along the tapered surface 7 a against the elastic force of the damper mechanism 9. At this time, the movable pressing portion 8 approaches the core shaft 4 side so as to reduce the distance D between the movable pressing portion 8 and the core shaft 4 while being guided by the tapered surface 7a. Then, as shown in FIGS. 3A and 3B, the sintered bearing W is pressed in a state where the movable pressing portion 8 is pushed downward by the upper punch 5 until there is no gap between the adjacent movable pressing portions 8. The upper and lower surfaces are pressed by the upper punch 5 and the lower punch 6, and at the same time, the inner and outer peripheral surfaces of the sintered bearing W are pressed by the core shaft 4 and the movable pressing portion 8. That is, all the pressing force applied to the sintered bearing W is adjusted by the amount of stroke downward of the upper punch 5.

  When the sizing of the sintered bearing W is completed in this way, the upper punch 5 rises as shown in FIG. When the upper punch 5 is lifted in this way, the movable pressing portion 8 is automatically lifted on the tapered surface 7a by the elastic force of the damper mechanism 9, and the interval D with the core shaft 4 is expanded. As a result, the movable pressing portion 8 is separated from the outer peripheral surface of the sintered bearing W after sizing, and a gap is formed again between them. In this state, the lower punch 6 is raised, and the sized sintered bearing W is lifted up to the upper surface of the die 3 as shown in FIG. 5, and the sized sintered bearing W is taken out from the upper surface of the die 3. .

  The sintered bearing W having a U-shaped cross section sized in this way, for example, as shown in FIG. 6, has a portion corresponding to the inner peripheral surface of the arc portion Wb as a bearing surface, and is a thrust shaft of the rotary shaft X. Used as a sintered bearing to support the load.

  And if it is the sintered bearing W manufactured in this way, the surface opening rate of an inner peripheral surface is 5% or more and less than 50%, the surface open area ratio of an outer peripheral surface is 20% or more and 50% or less, and The surface area ratio of the outer peripheral surface can be made larger than the surface area ratio of the inner peripheral surface. In this way, the surface open area ratio of the inner and outer peripheral surfaces of the sintered bearing W is approximately the same as that of the sintered bearing having an inner and outer peripheral surface shape whose cross-sectional shape is a perfect circle. In addition, since the surface aperture ratio of the outer peripheral surface is set to be larger than the surface aperture ratio of the inner peripheral surface, the following advantages are enjoyed when used in a state of being impregnated with lubricating oil. be able to. That is, if the surface opening ratio on the outer peripheral surface side is larger than the surface opening ratio on the inner peripheral surface side, the space in which the lubricating oil can be held inside increases on the outer peripheral surface side. An appropriate amount of lubricating oil is sequentially supplied from the outer peripheral surface side holding a large amount of lubricating oil to the inner peripheral surface side having a smaller surface opening ratio than the outer peripheral surface side, thereby realizing stable sliding characteristics. Is possible.

  In addition, although not shown, a linear mark is formed on the outer peripheral surface of the sintered bearing W along the mating surfaces of the divided movable pressing portions 8.

  As described above, according to the sizing device 1 according to the present embodiment, the sintered bearing W is accommodated by moving the movable movable portion 8 divided of the die 3 so that the distance D to the core shaft 4 is reduced. Since the accommodation hole 2 thus made is reduced, it becomes possible to directly press the sintered bearing W toward the core shaft 4 side while simplifying the outer peripheral surface shape of the sintered bearing W by the individual movable pressing portions 8. Therefore, as compared with the conventional case, the sintered bearing is more compact than the case where the inner and outer peripheral surfaces of the sintered body are deformed so that the inner and outer peripheral surfaces of the sintered body are brought into close contact with the die and the core shaft by only compressing the sintered body by the upper punch and the lower punch. A pressing force is directly applied to the inner and outer peripheral surfaces of W. Therefore, it becomes difficult to generate a portion where the pressing force applied to the inner and outer peripheral surfaces of the sintered bearing W is insufficient, and as a result, highly accurate sizing can be performed.

  Further, after the sizing of the sintered bearing W is completed, each movable pressing portion 8 is moved so that the receiving hole 2 is enlarged, so that the movable pressing portion 8 is automatically separated from the outer peripheral surface of the sintered bearing W after sizing. . Therefore, as shown in FIG. 5, when the sintered bearing W after sizing is taken out, no galling occurs between the movable pressing portion 8 and the outer peripheral surface of the sintered bearing W. It is possible to reliably reduce the rate at which sizing defects occur.

  In addition, this invention is not limited to said embodiment at all, In the range which does not deviate from the summary of this invention, it can implement with a various form. For example, in the above-described embodiment, the case where the sintered bearing W whose axial cross section is U-shaped is sized has been described as an example. However, the sintered bearing W may have a plurality of planes and the outer peripheral surface shape. When it is formed (specifically, when the outer peripheral surface is a polygon such as a rectangle), or when the outer peripheral surface is formed by combining a flat surface and a curved surface (specifically, an ellipse shape) (Track shape), etc.) or a case where the outer peripheral surface shape is formed by combining a plurality of partial cylindrical surfaces having different curvatures. Specifically, as shown in FIGS. 7A and 7B, when sizing a sintered bearing W having a quadrangular cross-section at right angles to the axis, it corresponds to each side of the sintered bearing W having a quadrangular cross-section. As described above, the movable pressing portion 8 is divided, and the divided movable pressing portion 8 is configured to be movable so as to expand and contract the distance from the core shaft, whereby high-precision sizing can be realized. Further, with respect to the sintered bearing W having a polygonal cross section, if the movable pressing portion 8 is divided so as to correspond to each side, high-precision sizing can be similarly realized.

DESCRIPTION OF SYMBOLS 1 Sizing apparatus 2 Accommodating hole 3 Die 4 Core shaft 5 Upper punch 5a Through hole 5b Pressing surface 5b1 High part surface 5b2 Low part surface 6 Lower punch 6a Through hole 6b Pressing surface 7 Fixed part 7a Tapered surface 8 Movable pressing part 9 Damper mechanism W Sintered body Wa Linear part Wb Arc part

Claims (10)

A sintered bearing having an outer peripheral surface shape having a non-circular cross-sectional shape,
A sintered bearing characterized in that the outer peripheral surface shape is formed by connecting together processed surfaces sized by a plurality of press surfaces divided in the circumferential direction.   2. The sintered bearing according to claim 1, wherein in the outer peripheral surface shape, linear marks are formed between the work surfaces connected to each other so as to follow the division position of the press surface.   The sintered bearing according to claim 1 or 2, wherein the outer peripheral surface has a U-shape.   The surface opening ratio of the inner peripheral surface is 5% or more and less than 50%, the surface opening ratio of the outer peripheral surface is 20% or more and 50% or less, and the surface opening ratio of the outer peripheral surface is the surface opening of the inner peripheral surface The sintered bearing according to any one of claims 1 to 3, wherein the sintered bearing is larger than the rate. A die having a housing hole for housing a sintered body having an outer peripheral surface shape having a non-circular cross-sectional shape, a core shaft inserted into an inner circumferential surface of the sintered body housed in the housing hole, A sintered body sizing device comprising an upper punch and a lower punch for pressing the sintered body accommodated in the accommodation hole from above and below,
The die includes a fixed portion and a movable pressing portion,
The movable pressing portion forms the accommodation hole and is divided into a plurality of portions in a circumferential direction, and is configured to expand and contract the accommodation hole by moving each divided portion. Sizing device.   The fixed portion of the die has a tapered surface inclined in a direction approaching the core axis toward the lower side, and the accommodation hole expands / contracts when the movable pressing portion moves up and down along the tapered surface. The sizing device for a sintered body according to claim 5.   An elastic member that elastically supports the movable pressing portion with respect to the fixed portion from below is provided, and the movable pressing portion moves downward against the elastic force of the elastic member, thereby reducing the accommodation hole. Item 7. A sizing apparatus for a sintered body according to Item 6.   The sintered body sizing device according to claim 5 or 6, wherein the movable pressing portion is moved downward by pressing the movable pressing member downward with the upper punch.   The sizing device for a sintered body according to claim 8, wherein the upper punch has a first pressing surface that presses the upper surface of the sintered body and a second pressing surface that presses the upper surface of the movable pressing portion. A method for sizing a sintered bearing having an outer peripheral surface shape having a non-circular cross-sectional shape,
A method for sizing a sintered bearing, characterized in that the outer peripheral surface shape of the sintered bearing is sized by a press surface divided into a plurality in the circumferential direction.

Images