JP2009062560A - Method for manufacturing sintered parts and sintered parts manufactured with the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively arrange a chamfer portion in a two-step chamfer part with a die molding process while inhibiting the life of the die from being shortened, because though the chamfer portion in the two-step chamfer part is arranged on the edge or the like of a bore of sintered parts with a machining process, the method costs too much. <P>SOLUTION: This manufacturing method includes: forming a green compact 7 having a first slope 4a which forms an angle θ1 with respect to an inner diameter surface 6 and a land 4c which forms an angle larger than θ1 with respect to the inner diameter surface 6 on the edge of the parts to be chamfered, by molding a powder with the die in a molding process of the green compact; subsequently sintering the green compact; and then squashing the land 4c of the sintered compact with the die to form a second slope 4b which forms an angle θ2(θ2<θ1) with respect to the inner diameter surface 6 and continues to each of the first slope 4a and the inner diameter surface 6. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides a sintered part manufactured by a powder metallurgy method, in particular, a sintered part in which a chamfered portion is applied to each of the inner diameter surface of the main body or an intersection between the outer diameter surface and the end surface, and the parts at low cost. The present invention relates to a manufacturing method for manufacturing.

  An example of a sintered part manufactured by powder metallurgy is shown in FIGS. The illustrated sintered part 1 is provided with a shaft hole 3 in the center of the main body 2, smooth insertion of the shaft into the shaft hole 3, prevention of shaft damage due to the opening edge of the shaft hole 3, A chamfered portion 4 is provided on the opening edge of the shaft hole 3 for the purpose of preventing the opening edge from being chipped.

  The chamfered portion 4 formed at the opening edge of the shaft hole is usually machined by C chamfering in the enlarged view of the chain line frame in FIG. 8 having an inclination angle of 45 ° with respect to both the end surface of the component and the inner diameter surface of the shaft hole. Provided.

The chamfering process for removing sharp edges such as holes is a technique that is generally used. In addition to C chamfering in which the chamfered portion 4 is formed by one plane, 2 disclosed in Patent Document 1 below. Step chamfering is also known. Two-step chamfering is formed by two flat surfaces (chamfered surfaces) intersecting an obtuse angle.
JP-A-5-8110

Machining chamfering is expensive. If the chamfer is C chamfer,
The resistance when pressing the shaft into the shaft hole is large, and a high insertion pressure may be required.

  On the other hand, when the two-step chamfering disclosed in Patent Document 1 is applied to the opening edge of the shaft hole, the inclination of the chamfered surface becomes tight on the inner side of the shaft hole, so that the insertion resistance of the shaft to the shaft hole is reduced. There is an effect to. However, since this two-step chamfering is also performed by machining, the problem of processing cost is not solved.

  Note that the chamfered portion provided at the edge of the shaft hole of the sintered part is not formed by molding with a mold in the compacting process for molding the raw material powder because it is difficult to ensure the durability of the mold. For example, if the chamfered portion 4 in FIG. 8 is to be molded with a mold, a mold having a sharpened chamfered portion 4 provided at the tip is sharpened at an angle of 45 °, and the edge of the tip of the mold is It is difficult to make a mold that can easily be chipped and can withstand practical use. Because of this problem, the chamfered portion is conventionally provided by machining, which causes the above-described problem of cost increase.

  An object of the present invention is to make it possible to install a two-step chamfered chamfered portion at a low cost by molding, such as at the edge of a shaft hole of a sintered part, while suppressing a decrease in the lifetime of the mold.

  In order to solve the above-described problem, in the present invention, a chamfered portion is provided at an intersection between an inner diameter surface or an outer diameter surface and a surface adjacent thereto, and the chamfered portion is connected to the first slope, and the inner diameter An angle θ1 formed by the first inclined surface and the inner diameter surface or the outer diameter surface, and the second inclined surface and the inner diameter surface. Alternatively, the following configuration is added to the method for manufacturing a sintered part in which the angle θ2 formed with the outer diameter surface has a relationship of θ2 <θ1. That is, in the green compact molding process, the first slope is molded into a green compact by molding, and then the green compact is sintered, and then the second slope is molded in the sizing process. It was formed by molding.

  In this method, in the green compact forming step, an angle formed between the first inclined surface and the inner surface or the outer surface is connected to the first inclined surface and the inner surface or the outer surface with an angle. A land set larger than the angle θ1 formed by the first slope, preferably a land perpendicular to the axis of the part, is molded into a green compact by molding, and the land is sized after sintering. If the second inclined surface is formed by crushing with a mold in the process, the protective effect of the mold used in the green compact molding process can be easily improved.

  The manufacturing method of the present invention can be suitably used when, for example, the chamfered portion is applied to the opening edge on one end side and the other end side of the shaft hole of the component for a sintered part having a penetrating shaft hole, At this time, the opening edge on one end side of the shaft hole of the sintered part (sintered body) is pressed with the taper forming surface of the chamfered cone to form the second inclined surface on one end side, and then the sizing of the sintered body is performed. In this sizing process, a stepped core is used as a mold for correcting the shaft hole, and the other end of the sintered body is pressurized by pressing the opening edge of the shaft hole on the taper molding surface of the stepped core. It is preferable to form the second slope on the side. According to this procedure, it is not necessary to repeat sizing.

The sintered part manufactured by the method of the present invention is provided with a chamfered portion at the intersection of the inner diameter surface or the outer diameter surface and the adjacent surface, and the chamfered portion is adjacent to the inner diameter surface or the outer diameter surface. A first inclined surface that intersects with the surface at an obtuse angle, and a second inclined surface that has one end at the first inclined surface and the other end at an obtuse angle with the end surface, and the first and second inclined surfaces are both Those that have been molded surfaces,
Alternatively, a shaft hole penetrating the main body is formed, and chamfered portions are formed at one end opening edge and the other end opening edge of the shaft hole, respectively, and the chamfered portion intersects the obtuse angle with respect to the end surface of the part. One inclined surface, one end is formed on the first inclined surface, and the other end is formed on a second inclined surface that intersects the inner diameter surface of the shaft hole at an obtuse angle, and both the first inclined surface and the second inclined surface are molded. It becomes what has become the surface. In the present invention, the sintered part is also provided.

  In the method of the present invention, the first inclined surface is formed in the green compact forming step among the first and second inclined surfaces constituting the chamfered portion, and the second inclined surface is a sizing step after the green compact is sintered. Since the first slope is formed separately, the slope angle of the second slope installation region at the time of forming the first slope (slope angle based on the surface intersecting the inner diameter surface or the outer diameter surface) is smaller than the slope angle of the second slope. . For this reason, compared with the case where the 1st slope and the 2nd slope are shape | molded simultaneously, the strength fall of the front-end | tip of a powder molding die is suppressed. By providing the land in the installation area of the second slope, the inclination angle of this area can be set to 0 ° (the angle formed with the axis of the component is 90 °).

  Further, if the land remains in the sintered part, for example, the same edge as that when not chamfering is generated at the end of the land, and the chamfering effect is not exhibited. The land is crushed with a mold for forming the second slope, and the angle of the edge generated at the intersection with the inner diameter surface or the outer diameter surface is blunted. The mold at this time may be a chamfered cone having a tapered molding surface at the tip or a stepped core of a sizing mold having a tapered molding surface on the outer periphery in the middle of the length. This can be avoided, and the second inclined surface can be formed with a mold.

  Due to the above effects, the chamfered portion can be formed without performing machining that is disadvantageous in terms of cost, and the processing cost is reduced and the cost is reduced.

  In the case where the land is formed at a right angle to the axis of the part, the land molding surface at the tip of the mold is formed by a plane perpendicular to the axis, so that a sharp edge that is easily chipped at the tip of the mold cannot be formed. , The effect of reinforcing the die tip is further increased.

  Embodiments of the present invention will be described below. 1 and 2 show an example of a sintered part produced by the method of the present invention. This sintered part 1 is provided with a shaft hole 3 penetrating through the center of a ring-shaped main body 2, and chamfered portions 4 are respectively provided at an opening edge on one end side and an opening edge on the other end side of the shaft hole 3. Is provided. The chamfered portion 4 includes a first inclined surface 4a that intersects with the end surfaces 5 and 5 of the sintered part 1 at an obtuse angle, a surface that has one end intersecting the first inclined surface 4a and the other end intersecting the end surfaces 5 and 5 (see FIG. These parts are constituted by second inclined surfaces 4b that intersect each of the inner diameter surface 6) of the shaft hole 3 at an obtuse angle.

  The sintered part 1 is manufactured through a raw powder compacting process, a sintering process, and a sizing process, and the chamfered portion 4 is formed in the manufacturing process.

  FIG. 3 shows a powder molding die used for manufacturing the sintered part 1 of FIG. The mold 10 is composed of a die 11 for molding the outer periphery of a sintered part, an upper punch 12 and a lower punch 13 facing each other for molding an end surface of the part, and a core 14 for molding a shaft hole of the part. Yes.

  The upper punch 12 and the lower punch 13 have an annular convex portion 16 on the inner peripheral side of the molding surface 15 that molds the end surface of the component. The convex portion 16 has a land forming surface 16b having a flat surface perpendicular to the axis of the mold, and the portion between the outer periphery of the land forming surface 16b and the forming surface 15 is for the first slope. Are connected by an inclined molding surface 16a.

  FIG. 4 shows the shape of the shaft hole opening edge of the green compact obtained by molding with the powder molding die shown in FIG. At the opening edge of the shaft hole 3 provided in the green compact 7, there are a first inclined surface 4 a that intersects an obtuse angle with respect to the end surface of the component, and a land 4 c that is disposed between the first inclined surface 4 a and the inner diameter surface 6. Is formed. Although not shown, the shape of the opening edge on the other end side of the shaft hole 3 is the same as that in FIG. The first inclined surface 4a has an angle θ1 formed with the inner diameter surface 6 of 150 °, but is not limited to this angle.

  The green compact obtained through the compacting process is introduced into a sintering furnace and sintered, and then the land 4c of the obtained sintered body 8 is crushed with a mold.

  FIG. 5 shows a chamfering cone 17 and a stepped core 18 for sizing used to finish an incomplete chamfered portion formed in the sintered body. Before sizing, the chamfering cone 17 is used to machine the shaft hole opening edge on one end side of the sintered body 9. The chamfering cone 17 has a taper forming surface 17a, and a portion where the land 4c is formed is pressed and plastically deformed by the taper forming surface 17a, and the second inclined surface 4b shown in FIG. Form. Thereafter, sizing of the sintered body is performed, and in this sizing process, a stepped core 18 as shown in FIG. 5 is used as a mold for correcting a shaft hole, and taper forming is present in the middle of the stepped core 18. The shaft 18 opening edge on the other end side of the sintered body 8 is pressurized with the surface 18a to form the second inclined surface 4b on the other end side. The second inclined surface 4b has an angle θ2 formed with the inner diameter surface 6 of the shaft hole 3 of 30 °. However, when the angle θ2 is 45 °, there is no difference from general C chamfering, and there is an effect of two-step chamfering. Since the angle is not exhibited, the inclination angle θ2 is preferably 45 ° or less.

  After the above steps, the two-step chamfered chamfered portion 4 shown in FIG. 6 is formed at the opening edges at both ends of the shaft hole 3, and the finished sintered part 1 is obtained.

Note that both the second inclined surface of the chamfered portion on the one end surface side of the sintered part and the second inclined surface of the chamfered portion on the other end surface side can be formed of a chamfered cone.
Further, the above description is directed to a sintered part having a penetrating shaft hole, and chamfered portions having the first slope and the second slope at the opening edges on one end side and the other end side of the shaft hole of the part, respectively. Although the case where it gave is given as an example, it can be used also when forming a chamfered portion for the purpose of preventing the chipping of the edge on the outer peripheral edge of the end face of the sintered part.

Plan view showing an example of a sintered part manufactured by the method of the present invention Sectional drawing which expands and shows the chamfered part provided in the shaft hole opening edge of the sintered part of FIG. Sectional drawing of the principal part of the metal mold | die for powder molding used for manufacture of the sintered component of FIG. FIG. 3 is an enlarged cross-sectional view of a shaft hole opening edge portion of a green compact formed by the mold of FIG. Front view of chamfering cone and stepped core forming second slope of chamfered portion Sectional view showing enlarged chamfered part Plan view showing a conventional example of sintered parts Sectional view of the sintered part of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sintered part 2 Main-body part 3 Shaft hole 4 Chamfer 4a 1st slope 4b 2nd slope 4c Land 5 End surface 6 Surface (inner diameter surface) which cross | intersects end surface
7 Green compact 8 Sintered body 10 Mold 11 for powder molding Die 12 Upper punch 13 Lower punch 14 Core 15 Molding surface 16 Convex portion 16a First slope molding surface 16b Land molding surface 17 Chamfering cone 17a Taper molding surface 18 Stepped core 18a Tapered molding surface

Claims (7)

A chamfered portion (4) is provided at a corner portion where the inner diameter surface (6) or the outer diameter surface intersects with the adjacent surface (5), and the chamfered portion (4) is connected to the surface (5). (4a) and the inner surface (6) or the outer surface and the second inclined surface (4b) connected to the first inclined surface (4a), the first inclined surface (4a) and the inner surface (6) Or an angle θ1 formed with the outer diameter surface and an angle θ2 formed between the second inclined surface (4b) and the inner diameter surface (6) or the outer diameter surface are manufactured as a sintered part having a relationship of θ2 <θ1. A method,
In the green compact molding step, the first slope (4a) is molded with a mold to form a green compact (7), then the green compact (7) is sintered, and then in the sizing step A method for producing a sintered part, wherein the second slope (4b) is formed by molding with a mold.   In the green compact forming step, the inner surface (6) or the outer surface that is connected to the first inclined surface (4a) and the first inclined surface (4a) and both the inner surface (6) or the outer surface with an angle. A land (4c) whose angle formed with the radial surface is set to be larger than an angle θ1 formed with the first inclined surface (4a) is molded with a mold to form a green compact (7). The method according to claim 1, wherein the second inclined surface (4b) is formed by crushing with a mold in a sizing step after sintering.   The method for manufacturing a sintered part according to claim 2, wherein the land (4c) is formed at right angles to the inner diameter surface (6) or the outer diameter surface where the land intersects. The first inclined surface (4a) and the second inclined surface (4b) are provided at the opening edge on one end side and the opening edge on the other end side of the shaft hole (3) of the sintered part having the penetrating shaft hole (3). The manufacturing method of the sintered component in any one of Claims 1-3 which give a chamfer part (4), respectively.
  The green compact (7) in which the first inclined surfaces (4a) are respectively formed on the opening edges at both ends of the shaft hole (3) is sintered, and then the shaft hole of the obtained sintered body (8). The opening edge on one end side of (3) is pressurized with the taper forming surface (17a) of the chamfered cone (17) to form the second inclined surface (4b) on one end side, and then the sizing of the sintered body (8) is performed. In this sizing process, a stepped core (18) is used as a mold for correcting a shaft hole, and a shaft hole on the other end side of the sintered body is formed on the taper molding surface (18a) of the stepped core (18). The manufacturing method of the sintered component according to claim 4, wherein the second inclined surface (4 b) on the other end side is formed by pressurizing the opening edge.   A sintered part manufactured by the method according to any one of claims 1 to 5, wherein a chamfered portion (4) is formed at an intersection of an inner diameter surface (6) or an outer diameter surface and an end surface (5) adjacent thereto. The chamfered portion (4) has an obtuse angle with respect to the end surface (5), a first inclined surface (4a), one end on the first inclined surface (4a), and the other end on the inner diameter surface (6 ) Or the second inclined surface (4b) intersecting the outer diameter surface at an obtuse angle, and the first inclined surface (4a) and the second inclined surface (4b) are both die-molded surfaces. Bonding parts.   A sintered part manufactured by the method according to any one of claims 1 to 5, comprising a shaft hole (3) penetrating the main body (2), and one end opening of the shaft hole (3). A chamfered portion (4) is provided on each of the edge and the opening edge on the other end, the chamfered portion (4) intersects the end surface (5) of the component at an obtuse angle, and one end is the first One inclined surface (4a) is composed of a second inclined surface (4b) whose other end intersects with the inner diameter surface (6) of the shaft hole (3) at an obtuse angle, and the first inclined surface (4a) and the second inclined surface (4a). Sintered parts in which the slope (4b) is a die-molded surface.

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