JP2014100738A - Powder molding die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy of products by providing flanges on an outer periphery of one end of a boss part, and reducing inclination of the flanges and irregularity of the end surface caused by sinter in a sintered component on which concavities and so on are provided and the concavities cause density difference of the flanges.SOLUTION: In the powder molding die for molding powder molding body of a sintered component having flanges on an outer periphery on one end of a boss part and concavities, grooves and holes distributed unevenly on a way of peripheral direction of the flanges, a molding surface of punch for molding the flanges of the molding body, is inclined to a direction which absorbs inclination and irregularity caused by sinter of the flanges.

Description

  The present invention relates to a sintered part having a ridge on the outer periphery of one end of a boss part, and more particularly to a powder molding die used for manufacturing a sintered part in which a recess, a groove, and the like are unevenly provided in a ridge.

  FIG. 9 shows an example of a brazed sintered part manufactured by powder metallurgy. The illustrated sintered component 10 is a compressor bearing used in an air conditioner or the like, and has a flange 12 on the outer periphery of one end of the boss portion 11. Concave portions 13 are unevenly provided on the end surface of the flange 12 on the boss portion side.

  Such a sintered part is made by sintering a powder compact, and a sintered part 10 having a shape shown in FIG. 9 is a die in which a die 1, an upper punch 2, a lower punch 3 and a core rod 4 are combined. As shown in FIG. 10, the powder put into the cavity is compressed with upper and lower punches to form a powder compact A, and the compact is sintered. For example, when the end surface f1 on the side opposite to the boss portion of the flange 12 is a plane perpendicular to the axis, the mold for molding the molded body has a molding surface (lower surface) of the upper punch 2 that molds the end surface f1 perpendicular to the axis. What is used on the surface is used.

The same applies to the lower punch 3. For example, when making a molded body having the shape of FIG. 9, three lower punches 3 ₋₁ , 3 ₋₂ , and 3 _{−3 of} lower 1 to lower 3 are used, and an end surface f2 on the boss portion side of the sintered part. Is a plane perpendicular to the axis, a molding surface (upper surface) of the lower punch _3-1 that molds the surface is used as a plane perpendicular to the axis (for example, see Patent Document 1 below). .

JP-A-11-223189 Japanese Patent Laid-Open No. 5-93202

  In the sintered part 10 as shown in FIG. 9, an inevitable difference occurs in the density of the boss portion 11 and the flange 12. Moreover, since the recessed part which produces a local thickness change is unevenly provided in the collar, a difference arises also in the density of each part of the collar 12. FIG. The product with a long axial length of the boss part 11 has a tendency that the powder for the boss part flows to the heel side at the time of molding, but there is a difference in the powder flow between the recessed part installation side and the other part side. For this reason, the density difference between each part of the ridge tends to increase.

  When the green body is sintered due to the difference in density or the shape of a special ridge, the product is distorted, causing axial deflection (an inclination of the ridge) and deterioration of the flatness (warp) of the ridge.

  In addition, in the above-mentioned patent document 2, in order to suppress the deterioration of the flatness of the lower surface of the ridge (the end surface on the side opposite to the boss portion), the thickness of the ridge increases on the outer diameter side of the heel when forming the powder. It is proposed to sinter the molded body in such a manner that it is inclined in a taper shape with the lower surface facing upward.

  However, in the sintered part as shown in FIG. 9, the distortion of the wrinkles is not constant in each part in the circumferential direction due to the influence of unevenly distributed recesses and the like. An effective suppression cannot be expected.

  According to the present invention, a boss is provided on the outer periphery of one end of the boss portion, and the inclination due to sintering of the heel and distortion of the end surface of a sintered part provided with a recess or the like that causes a density difference in the heel are reduced. The task is to improve accuracy.

In order to solve the above-described problems, in the present invention, powder molding of a sintered part having a flange on one end outer periphery of the boss portion, and having a recess, a groove or a hole unevenly provided in the circumferential direction of the flange. The following ingenuity was applied to the punch of the powder molding die for molding the body.
That is, a part or the whole of the molding surface for molding the punch of the punch molded body was inclined in a direction to absorb inclination and strain caused by sintering of the punch.

  The punch molding surface is a flat molding surface that is inclined, and the outer diameter side is a conical surface that recedes in the axial direction. Two types are possible: a tilt due to sintering and a tilt inclined to absorb strain.

  In both forms of the molding surface, the molding surface is inclined in a range in which the height difference of the molding surface caused by inclining the surface is smaller than the dimensional tolerance of the ridge.

  Although the present invention is mainly applied to the upper punch, since the end surface of the flange formed on the lower punch may also be inclined or distorted by sintering, the molding surface of the lower punch is inclined, or It can also be a conical surface with an inclined axis.

  The powder molding die according to the present invention imparts an inclination in a direction opposite to the direction of strain generated by sintering to the wrinkles of the molded body before sintering by inclining the molding surface of the punch. Thereby, the inclination of the wrinkles and the distortion of the wrinkles generated by the sintering are absorbed, and a product (sintered part) with improved accuracy is obtained.

Sectional drawing which shows an example of the metal mold | die for powder molding of this invention End view of the upper punch of the powder mold shown in FIG. Sectional drawing along the BOB line of FIG. 2 of an upper punch Sectional drawing along the AOA line of FIG. 2 of the front-end | tip part of an upper punch Sectional drawing which shows the compression molding state of the powder by the metal mold | die for powder molding of invention of FIG. End view of the upper punch of another embodiment of the powder molding die of the present invention Sectional drawing along the C-O-C line of FIG. 6 of an upper punch Sectional drawing along the DOD line of FIG. 6 of the front-end | tip part of an upper punch (A) Perspective view showing an example of a sintered part produced by molding with the powder molding die of the present invention, (b) End view on the boss part side of the sintered part same as above Sectional view of a conventional powder molding die used for molding the sintered part of FIG.

Embodiments of a powder molding die according to the present invention will be described below with reference to FIGS. 1 to 8 of the accompanying drawings. The illustrated powder molding die is used for manufacturing the sintered compact for a sintered part shown in FIG. 9, and includes a die 1, an upper punch 2, a lower 1 punch 3 ₋₁ , and a lower 2 punch. The lower punch 3 composed of 3 ₋₂ and the lower 3 punch 3 ₋₃ and the core rod 4 are combined.

  In the powder molding die shown in FIG. 1, the upper punch 2 is devised, and the die 1, the lower punch 3, and the core rod 4 have the same configuration as the conventional die shown in FIG.

  As can be seen from FIG. 4 showing a cross section along the line A-O-A in FIG. 2, the upper punch 2 is formed by inclining the molding surface 2 a at the tip with a flat surface and tilting in one direction. FIG. 3 is a cross section taken along line B-O-B in FIG. 2, and the inclination of the molding surface 2 a does not appear in this figure.

  The inclination angle α shown in FIG. 4 of the molding surface 2a is within a range in which the thickness of the flaw of a sintered part manufactured using the mold shown in FIG. Is set so that the variation in the thickness of the wrinkles caused by is within dimensional tolerances).

  For example, in the case of a product having a ridge diameter of about 60 mm, if the gradient is about 5/100 mm to 15/100 mm, the variation in thickness of the ridge will be within the dimensional tolerance even if the molding surface 2a is tilted as shown in FIG. Can do.

The powder molding die of FIG. 1 configured in this way is a raw material powder in the cavity 5 formed between the die 1 and the lower punches 3 _{-1 to} 3 _-3 and the core rod 4. P is charged and the upper punch 2 is driven to compress the raw material powder P as shown in FIG.

  At this time, the inclination imparted to the molding surface 2a of the upper punch 2 is in a direction to absorb the inclination and distortion of the wrinkles resulting from the sintering of the sintered part to be manufactured. For this reason, the inclination and strain of the wrinkles due to sintering are canceled out, and the inclination and strain of the wrinkles of the product are reduced.

  6 to 8 show other forms of the upper punch. As shown in FIG. 8, the upper punch 2 is a sintered body that manufactures the axis L at the center of the cone with respect to the axis C of the upper punch 2 by forming the molding surface 2 a into a conical surface whose outer diameter side recedes in the axial direction. The thickness of the ridges of the connecting parts is inclined within an angle range that is within dimensional tolerances.

  In FIG. 7, which shows a cross section along the line C—O—C in FIG. 6, the upper punch 2 is inclined symmetrically with respect to the axis CL of the upper punch 2. On the other hand, in the cross section of FIG. 8 along the line D-O-D of FIG. 6, the molding surface 2 a is inclined so as to be symmetric with respect to the axis L inclined by β with respect to the axis CL of the upper punch 2. Accordingly, the inclination amount and distortion amount of the wrinkles corrected by the inclination of the molding surface are different on the opposite side with respect to the center of the upper punch.

  Depending on the size, number of installations, or arrangement of the recesses, grooves, and unevenly distributed holes in the sintered part, the entire area of the sintered product warps with the boss as a fulcrum. There may be a difference in the degree of warping on the opposite side.

  In such a case, it is effective to form the molding surface 2a of the upper punch 2 as described with reference to FIGS.

  The mold which makes the forming surface 2a a conical surface and inclines the central axis of the conical surface is also within the dimensional tolerance of the wrinkle thickness of the sintered part due to the forming surface 2a being the inclined conical surface. Inclination is imparted to the molding surface within a range that falls within the range.

  In the exemplary powder molding die, the molding surface of the upper punch is tilted, but the molding surface of the lower punch and the molding surfaces of the upper and lower punches can be tilted in the same manner as described above.

DESCRIPTION OF SYMBOLS 1 Die 2 Upper punch 2a Molding surface 3 Lower punch _3-1 Lower 1 punch _3-2 Lower 2 punch _3-3 Lower 3 punch 4 Core rod 5 Cavity P Raw material powder alpha Inclination angle CL of upper punch molding surface Upper punch axis Center L Inclination angle 10 of cone center surface of cone β relative to axis L of axis L of axis L Sintered component 11 Boss portion 12 鍔 13 Recess f1 End surface on opposite boss portion side of fist 鍔 End surface on boss portion side of 鍔

Claims (3)

  Powder molded body of sintered component (10) having a ridge (12) on the outer periphery of one end of the boss portion (11), and a recess (13), a groove or a hole being unevenly distributed in the circumferential direction of the ridge A mold for powder molding, comprising a die (1) and upper and lower punches (2, 3), a part of a molding surface (2a) for molding the punch of the molded body of the punch, A powder molding die in which the entire region is inclined in a direction to absorb the inclination and strain of the wrinkles caused by sintering.   2. The powder molding according to claim 1, wherein the molding surface (2a) of the punch is a flat molding surface, and the molding surface is inclined within an angular range in which the thickness of the flange (12) of the sintered part falls within a dimensional tolerance. Mold.   The punch forming surface (2a) is a conical surface whose outer diameter side recedes in the axial direction, and the axis (L) at the center of the cone is set to the thickness of the ridge of the sintered part with respect to the axis (CL) of the punch. The powder molding die according to claim 1, wherein the mold is tilted within an angular range that falls within a tolerance.

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