JP2010059526A - Method for sizing sintered part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the sizing of a sintered part which has a column between a first member and a second member and requires the sizing of the inside and outside diameter part of the first member while preventing contact and collision of an upper punch with the second member. <P>SOLUTION: A sizing mold is used which includes an upper punch 2 having an inner peripheral surface 2a of a shape including the second member 22 of the sintered part in end face view, a lower punch 3, a die 1 which corrects the outer diameter surface of the first member 21 with a molded hole 1a, and a guide member 4. A sintered part 20 mounted on the die 1 in such a manner that the second member 22 faces upward is positioned by inserting the guide member 4 into a through-hole 22a, and the sizing is performed in this state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for sizing a sintered part having a column such as a planetary carrier employed in a transmission of a vehicle.

  In general, a method for manufacturing a machine part by powder metallurgy includes a compression step of compressing raw material powder to obtain a molded body, a sintering step of introducing the obtained molded body into a sintering furnace and sintering, and a post-sintering process. This is a sizing process in which the parts (sintered parts) are recompressed to correct the dimensions.

  As described in Patent Document 1 below, in a general sizing process, a sizing die composed of an upper punch, a lower punch, and a die is used, and the upper and lower end faces of the sintered body are placed on the upper punch and the lower punch. The size of the product is corrected by compressing with a punch.

  For example, when correcting the dimensions of a cylindrical part of a sintered part with an inner flange having a flange formed on the inner peripheral surface of the cylindrical part, the part is pushed into the molding hole of the die with an upper punch, and the outer diameter surface of the cylindrical part is A method of constraining with a die, further constraining an inner peripheral surface with a core, and compressing the entire upper surface of the sintered part with an upper punch, an end surface of a cylindrical portion with a lower punch, and a lower surface of a flange with a lower two punch. Is taken.

JP-A-2-57622

  With respect to the sintered part with the inner collar, since the outer diameter surface of the cylindrical portion is constrained by the core and the die, sizing can be performed by pressing the entire upper surface with the upper punch. However, if the sintered part to be sized is the one in which the second member is arranged on the upper part of the flange via a plurality of pillars, the sizing by the method of pressurizing the entire upper surface with the upper punch is performed between the flange and the flange. It cannot be adopted due to the problem of damaging the arranged columns.

  As such a sintered part, for example, there is a planetary carrier employed in a transmission of a vehicle. An example of the sintered part is simplified and shown in FIG. The sintered component (planetary carrier) 20 is configured such that a plurality of pillars 23 are arranged between a first member 21 and a second member 22. The first member 21 has a through hole 21a at the center, and further has a cylindrical portion 21b at one end. The second member 22 also has a through hole 22a in the center, and the outer circumference of the cylindrical portion 21b of the first member and the inner diameter of the free end side of the cylindrical portion 21b (the surface of the first member when a spline or the like is formed here) ) Is corrected by sizing. The first member 21 has an outer diameter larger than that of the second member 22, and a portion serving as an end surface of the cylindrical portion 21 b projects outward in the radial direction from the column 23.

Since the sizing of the sintered part 20 cannot pressurize the entire upper surface, the sintered part 20 is placed with the second member 22 up and the free end of the cylindrical part 21b as shown in FIG. Of the (lower end), the outer periphery is positioned with the die 1 and the lower 2 punch _3-2 and placed in the sizing mold, and includes the second member 22 in the end view (without compressing the second member 22. The upper punch 2 having an inner peripheral surface 2a having a shape that can be inserted into the inner diameter portion is pressed by pressing the outer peripheral portion of the upper surface of the first member 21 into the molding hole 1a of the die.

  However, in this method, the sintered part 20 installed in the sizing mold may be tilted, and the height of the sintered part is high, so that when the sintered part is set tilted in the sizing mold, the upper punch However, there is a problem in that it comes into contact with the second member on the upper side in the lowering process, or collides to damage the sintered part, and in some cases, the upper punch is broken.

  Sintered parts such as the planetary carrier shown in FIG. 6 have inevitable strains due to powder molding and sintering before sizing. On the other hand, in the sizing, this sintered part is placed on a sizing mold, and then the die is raised to lift the sintered part to the rising end of the die and pressurize with the upper punch from that position. A method of proceeding sizing while lowering is adopted. In the process of ascent of the die, sintered parts having large strains are out of balance and tilted.

  In order to reduce damage due to the contact and collision of the upper punch due to this inclination, roundness selection work is performed on sintered parts used for sizing, and parts that are poor in roundness and easily inclined during sizing are removed in advance. Although the method was adopted, roundness selection work reduces productivity and increases labor costs.

  The present invention enables sizing of a sintered part such as a planetary carrier having a column between two members to prevent damage to the part and the upper punch, and eliminates the need for prior roundness selection work. The task is to do.

In order to solve the above problems, in the present invention, a plurality of columns are arranged between a first member having a through hole at the center and a cylindrical portion at one end and a second member having a through hole at the center. The following methods are provided as sizing methods for the bonded parts.
The method includes an upper punch having an inner peripheral surface including the second member in an end view, a lower punch for pressing the cylindrical portion of the first member, and an outer diameter surface of the first member as a forming hole. And using a sizing die having a guide member disposed on the inner diameter portion of the lower punch, the sintered part is placed on the die with the second member facing upward, The guide member is inserted into the central through hole of the second member, and the second member is positioned coaxially with the die forming hole. Sizing is performed in the positioning state. The shape including the second member here is a shape that can surround the outer periphery of the second member without colliding with the second member of the sintered part on the sizing mold positioned by the guide member.

  In this method, it is preferable to place the sintered part in a sizing mold and then raise the guide member and insert it into the central through hole of the second member. It is also preferable to raise the guide member by positioning the first member coaxially with the die forming hole with a die or a lower punch. Further, the guide member has a tapered portion with a small diameter at the tip side at the tip. It is also preferable to use.

  Further, the lower punch is composed of a cylindrical lower 1 punch that presses the end surface of the cylindrical portion of the first member, and a cylindrical lower 2 punch disposed between the lower 1 punch and the guide member. And supporting the cylindrical portion at the tip of the lower one punch, and inserting the tip of the lower two punch into the inside of the cylindrical portion to position the first member coaxially with the die forming hole, and in this state, It is also preferable to position the second member by the guide member.

  In the method of the present invention, a sizing die having a guide member disposed on the inner diameter portion of the lower punch is used. The guide member is inserted into the central through hole of the second member to position the second member, and in this state, the upper punch is lowered to pressurize the first member. Therefore, the firing member disposed on the sizing mold is used. The connecting part does not tilt beyond the allowable value, and contact and collision of the upper punch with the second member are avoided. This eliminates the problem of scratches and breakage of the sintered parts.

In addition, since sintered parts installed on the sizing mold will not tilt beyond the allowable value,
Roundness sorting work that hinders productivity improvement is also unnecessary.

Embodiments of the sizing method of the present invention will be described below with reference to FIGS. FIG. 1 shows a specific example of a sizing die used for dimensional correction of the sintered part of FIG. This sizing die is constituted by a die 1 having a forming hole 1 a, an upper punch 2, a lower punch 3 and a guide member 4. The lower punch 3 is a combination of the lower 1 punch _3-1 and the lower 2 punch _3-2 .

The die 1 has an inner diameter that creates a gap between the inlet portion of the molding hole 1 a and the outer periphery of the cylindrical portion 21 b of the sintered part 20. By appropriately setting the inner diameter of the inlet portion of the molding hole 1a, the cylindrical portion 21b is inserted into the inlet portion of the molding hole 1a, and the first member 21 (the free end of the cylindrical portion 21b) is coaxial with the center of the molding hole 1a. Although it is possible to position upward, in the illustrated sizing method, the first member 21 (the free end of the cylindrical portion 21b) is positioned at the tip of the lower 2 punch _3-2 . The outer diameter of the tip of the lower 2 punch _3-2 is slightly smaller than the inner diameter of the free end of the cylindrical portion 21b, and slightly protrudes upward from the upper surface of the die 1 pulled down to the initial position. The first member 21 is inserted into the free end of the cylindrical portion 21b and positioned coaxially with the molding hole 1a.

  The upper punch 2 is a hollow punch having an open end, and has an inner peripheral surface 2a having a shape including the second member 22 of the sintered component 20 in an end view. Here, the shape including the second member is a shape as defined above.

The lower 1 punch _3-1 is a cylindrical punch that is inserted into the die forming hole 1 a and presses the end surface on the free end side of the cylindrical portion 21 b of the first member 21.

The lower 2 punch _3-2 is a cylindrical punch and is disposed between the lower 1 punch _3-1 and the guide member 4. The lower two punch 3 _-2, the outer diameter of the tip is smaller than the outer diameter of the molding portion 3 _-2a, forming hole 1a of the first member 21 by inserting the tip inside the cylindrical portion 21b Position concentrically with.

  The guide member 4 is constituted by a core rod, and the second member 22 is positioned by inserting the distal end portion of the guide member 4 into the through hole 22a. The guide member 4 is preferably provided with a tapered portion 4a having a small diameter on the distal end side, and the position of the second member 22 when the guide member 4 is inserted into the through hole 22a using the centripetal effect by the tapered portion 4a. Misalignment can be corrected.

The die 1 is supported by the die plate 5, and the upper punch 2 is supported by the upper punch plate 6. Further, the lower two punch _{3 -2} under 1 punch _{3 -1,} are individually supported by the lower punch plate 7,8, the guide member (core rod) 4 is supported by yoke plate 9. 10 is an elevating mechanism for the guide member 4 interposed between the yoke plate 9 (the cylinder actuator in the figure), 11 is a holder for holding the guide member 4, and 12 is a stroke for setting the ascending position of the guide member 4. This is an adjustment stopper ring. The die 1 is driven by a lifting mechanism (not shown) and moves up and down together with the die plate 5. Under 2 punch _3-2 also has a lifting function, under 1 punch 3 _-1 is supported received from below by a spring which can flex during component compressed by the upper punch 2 (not shown. Not required) .

The sintered component 20 is placed on the sizing mold configured as described above. At this time, as shown in FIG. 2, the die 1 and the guide member 4 are lowered to the initial position, and the free end (lower end in the figure) of the cylindrical portion 21b of the sintered part 20 is received by the lower 1 punch _3-1 . support. Also, positioning the first member 21 to the forming hole 1a coaxially by inserting the tip of the lower two punch 3 _-2 through hole 21a.

  Next, the guide member 4 is raised as shown in FIG. 3, and the guide member 4 is inserted into the through hole 22a at the center of the second member 22 to position the second member 22 coaxially with the molding hole 1a. Thereafter, the die 1 is raised to a predetermined position (a chain line position in FIG. 1). At this time, the sintered part 20 is also supported by the die 1 and lifted simultaneously. Conventionally, the sintered component 20 sometimes tilts in this process. However, in the method of the present invention, the sintered component 20 is maintained in a substantially straight posture while being guided by the guide member 4 and is raised to a fixed position. The outer diameter of the guide member 4 is appropriately set in consideration of the dimensional tolerance between the inner diameter of the through hole 22 a and the outer diameter of the second member 22. Specifically, the radial escape amount g1 (see FIG. 3) with respect to the inner peripheral surface of the through hole 22a is smaller than the radial escape amount g2 (see FIG. 2) of the inner peripheral surface 2a of the upper punch with respect to the second member 22. The inclination of the sintered part 20 is regulated by the restriction by the guide member 4.

  After the guide member 4 is lifted, the upper ram (not shown) of the press machine is driven and the upper punch 2 is lowered.

When the lowered upper punch 2 comes into contact with the upper surface of the first member 21, the guide member 4 is pulled down. And after that, formal pressurization by the upper punch 2 is performed, and the cylindrical portion 21b of the first member 21 pushes down the die 1 by the pressurization, and between the die forming hole 1a and the lower 2 punch _3-2. Sizing is performed by pushing in (see FIG. 4).

Thereafter, as shown in FIG. 5, the lower 1 punch _3-1 is pushed up to the initial position, the die 1 is pulled down to the initial position, and the sintered part 20 that has finished sizing is taken out of the sizing mold. This completes one cycle of work.

  In this method, the sintered component 20 with the second member 22 up is positioned on the upper side by the guide member 4 as described above, and therefore, the inclination of the sintered component 20 is such that the second member 22 and the guide member are inclined. 4 is limited to a range limited by a radial clearance amount g1 between 4 (substantially close to 0).

  As a result, the contact and collision of the upper punch 2 with the second member 22 are avoided, damage to the sintered parts is prevented, and the inclination of the sintered parts is suppressed, so that a perfect circle required before sizing is conventionally required. The sorting work becomes unnecessary.

  Further, since the guide member 4 is raised after the sintered part 20 is installed on the sizing mold, the guide member is used when the sintered part is installed on the sizing mold and when the sintered part after sizing is taken out from the sizing mold. 4 is lowered and does not hinder the work, and even if the sintered part is heavy or the work space is restricted, the work is not difficult.

Furthermore, support receiving the cylindrical portion 21b at the tip of the lower 1 punch 3 _-1, and positioning the first member 21 to the forming hole coaxially by inserting the tip of the lower two punch _3-2 inside the cylindrical portion 21b Since the guide member 4 is raised, the support of the sintered part by the sizing mold is stabilized, the inclination of the sintered part is more effectively suppressed, and the insertion of the guide member 4 into the through hole 22a of the second member 22 is troublesome. Will be lost.

Sizing of the sintered part (planetary carrier) described in FIG. 6 was performed by the method of the present invention using the sizing mold of FIG. The total number of sizing was 100,000. In addition, the roundness selection work in advance of the sintered parts for sizing was not performed. As a result, the upper punch did not collide with the sintered part, and there was no damage to the sintered part due to the upper punch contact, collision, or damage to the sintered part.
The effectiveness of the method of the present invention could be confirmed by this evaluation test.

Sectional drawing which shows the outline | summary of the sizing metal mold | die utilized for implementation of the method of this invention Sectional view showing the installation state of sintered parts to the sizing mold Sectional drawing which shows the positioning state of the 2nd member by a guide member Sectional view showing the pressed state of sintered parts by punch Sectional drawing which shows the taking-out state from the metal mold | die of the sintered part after sizing Sectional view showing an outline of an example of sintered parts to be sized Sectional view showing the positioning of sintered parts in the conventional sizing method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Die 1a Forming hole 2 Upper punch 2a Inner peripheral surface 3 Lower punch _3-1 Lower 1 punch _3-2 Lower 2 punch 4 Guide member 4a Tapered part 5 Die plate 6 Upper punch plate 7, 8 Lower punch plate 9 York plate 10 Lifting mechanism 11 Holder 12 Stroke adjusting stopper ring 20 Sintered part 21 First member 21a Through hole 21b Cylindrical portion 22 Second member 22a Through hole 23 Column g1 A radial escape amount g2 of the guide member with respect to the through hole of the second member Radial clearance of the inner surface of the upper punch for two members

Claims (5)

A plurality of columns (23) between a first member (21) having a through hole (21a) in the center and a cylindrical portion (21b) at one end and a second member (22) having a through hole (22a) in the center, respectively. ) For sizing the sintered part (20),
An upper punch (2) having an inner peripheral surface (2a) including a second member (22) in an end view, a lower punch (3) for pressing the first member (21), and a first Using a die (1) for correcting the outer diameter surface of the member (21) with a molding hole (1a) and a sizing die having a guide member (4) disposed on the inner diameter portion of the lower punch, the die (1) The sintered part (20) is installed with the second member (22) facing upward, and the guide member is inserted into a through hole (22a) in the center of the second member (22) of the sintered part (20). (4) is inserted, and the second member (22) is positioned coaxially with the die forming hole (1a).   The sintered part (20) is placed in a sizing mold, and then the guide member (4) is raised and inserted into the central through hole (22a) of the second member (22). A method for sizing sintered parts according to claim 1.   The guide member (4) is raised by positioning the first member (21) coaxially with the die forming hole (1a) by the die (1) or the lower punch (3). Sizing method for sintered parts.   The method for sizing a sintered part according to any one of claims 1 to 3, wherein the guide member (4) is one having a tapered portion (4a) having a small diameter on the tip side at the tip. The lower punch (3) has a cylindrical lower punch (3 _-1 ) that presses the end surface of the cylindrical portion (21b) at one end of the first member, the lower punch (3 _-1 ), and the guide. member constituted by 2's cylindrical lower two punches disposed between (4) _{(3 -2),} support receiving the cylindrical portion at the tip of the lower 1 punch _{(3 -1)} (21b), the lower The tip of the two punches ( _3-2 ) is inserted into the inside of the cylindrical portion (21b) to position the first member (21) coaxially with the die forming hole (1a). In this state, the guide member ( The method of sizing a sintered part according to any one of claims 1 to 4, wherein the second member (22) is positioned according to 4).

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