JP2009148813A - Compacting die, and sintered component compacted using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compacting die where, in two dies contacted with each other and relatively moving to the axial direction, the corner part of either die is provided with a round face or a slant face, and a lower-narrowed space in which power infiltrates into a space with the other die is made by the round face or the slant face, the biting of powder into the space between the dies is prevented. <P>SOLUTION: With a compacting die in which the first die (die 1) has a round face or a slant face 5c chamfering the corner part at which the compacting face pressurizing powder in a cavity 6 to the axial direction and the sliding face of the second die (lower punch 2) are crossed, and the cavity 6 is made by the die including the first die and the second die as the object for improvement, a flat land 9 put out from the lower edge of the round face or the slant face 5c toward the second die side is formed at the first die. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a powder molding die and a sintered part excellent in surface properties produced by sintering a green compact molded with the die.

  The sintered part is manufactured by compressing powder with a powder molding apparatus and sintering the obtained green compact. Molding of the green compact by the powder molding apparatus is performed using a mold apparatus (die set) including a die, an upper punch, and a lower punch as minimum elements.

  FIG. 8 shows a model for explaining the problem of the invention of the powder molding die employed in the die apparatus. The illustrated powder molding die includes a basic die 1, a lower punch 2, and an upper punch 3. The die 1 has a stepped forming hole 5.

  FIG. 9 shows a sintered part produced by sintering a green compact formed using this mold. The illustrated sintered part 10 has a convex portion 13 projecting laterally at one end of the side surface 12, and an R surface 14 connected to the side surface 12 is formed at a corner portion on the base side of the convex portion 13. Yes. In this sintered component 10, the end surface 11 of the convex portion 13 is pressed by the molding surface 5 a provided on the die 1, and the R surface 14 is molded by the R surface 5 c provided on the die 1. The R surface 5c of the die 1 is formed at the corner where the sliding surface (inner peripheral surface of the small diameter hole portion) 5b between the molding surface 5a and the lower punch 2 intersects.

FIG. 10 shows a process chart of powder molding by the mold of FIG. Powder molding is performed as follows. That is, the die 1 is raised from the initial state of FIG. 10 (a) to a predetermined position {FIG. 10 (b)}, and the powder is supplied from the powder feeding box 7 to the cavity 6 created between the die 1 and the lower punch 2. P is supplied {FIG. 10 (c)}. Next, when the filling of the powder P into the cavity 6 is completed, the powder feeding box 7 is retracted {FIG. 10 (d)}, and the upper punch 3 is lowered to compress the powder in the cavity {FIG. 10 (e)}. . Thereafter, the pressure is released and the upper punch 3 is returned, the die 1 is pulled down, and the finished green compact 10A is extracted from the mold {FIG. 10 (f)}.

  The R surface 5c may be replaced with a flat chamfered surface (chamfer surface).

The powder molding die and the powder molding method are disclosed in, for example, Patent Documents 1 and 2 below. The molds disclosed in these documents may be provided with an R surface and a chamfered slope at a location where the corner portion of the product is molded, but Patent Documents 1 and 2 provide the R surface and the slope. It does not say anything about the problems that occur. The same applies to other technical documents in the same field.
Japanese Utility Model Publication No. 5-46922 JP-A-8-47800

  When the powder was molded using the mold shown in FIG. 8, the powder was caught between the die and the lower punch, and the surfaces of both molds were damaged (the scratches are called peeling). The green compact may be rubbed by the surface of the mold to deteriorate the surface properties of the green compact. In an extreme case, the die and the lower punch may burn and the molding apparatus may not operate.

In the state where the die 1 is descending, the powder bite is formed in a space 8 (see FIG. 8) of the lower dent between the R surface 5c of the die and the lower punch 2, and enters the space 8. The powder is dragged between the sliding surfaces of the die 1 and the lower punch 2 when they move relative to each other in the axial direction. In particular, when the powder is supplied to the cavity 6 while the die 1 and the lower punch 2 are moved relative to each other, the powder is likely to be caught. In addition, the powder remaining around the entrance of the die forming hole may drop into the space 8 due to vibration or the like, and the die and the lower punch may move relative to each other in this state, and the powder may be caught. The biting of the powder causes deterioration of the surface properties of the green compact (and consequently the sintered part) and the occurrence of mold seizure.

  Accordingly, the present invention is directed to improvement of a powder molding die in which the R surface or the inclined surface is provided on one of two molds that move relative to each other in the axial direction in contact with each other. It is an object to be able to prevent the powder from being caught in the gap (sliding gap).

  In order to solve the above-described problems, in the present invention, a first mold and a second mold that are in contact with each other in the process of forming a green compact and relatively move in the axial direction are provided, and the first mold includes: A mold having an R surface or an inclined surface at a corner where a molding surface for pressing powder in the cavity in the axial direction and a sliding surface of the second mold intersect, and including the first mold and the second mold In the powder molding die in which the cavity is created by a die, a flat land protruding from the R surface or the slope toward the second die side is formed on the first die.

The flat land preferably has a width W set in the range of 0.03 to 0.5 mm, more preferably 0.05 to 0.2 mm, and also with respect to the sliding surface with the second mold. It is preferable that the surface is formed as a right angle crossing surface.

  When the first die is a die having a stepped molding hole, the lower punch becomes the second die. Further, when the lower punch is divided into a plurality of parts and the first divided body is used as the first mold, the second divided body of the lower punch becomes the second mold.

  The green compact molded by the mold of the present invention was molded by the R surface or the inclined surface of the first mold at the corner portion formed by the intersection of the end face stepped down in the axial direction and the side surface parallel to the axial center. It has an R surface or an inclined surface, and has a flat surface formed by the flat land of the first mold at the boundary between the R surface or the inclined surface and the side surface. In the present invention, a sintered part produced by sintering the green compact is also provided.

  Specific examples of the sintered parts include a bearing cap that holds the crankshaft of the engine and a gear with a boss that is incorporated into the engine drive system.

  In the powder molding die of the present invention, a flat bottom surface is created in a space (the lower hollow space 8 described with reference to FIG. 8) generated between the first die and the second die by the flat land provided in the first die. Thus, the powder is received by the bottom surface, and the powder is prevented from getting into the sliding gap when the first mold and the second mold move relative to each other in the axial direction. For this reason, scratches and seizures on the sliding surfaces of the first mold and the second mold are suppressed, the surface properties of the sintered parts deteriorate due to the scratches and seizures, and the operating rate of the powder molding apparatus decreases. Is less likely to occur.

The flat land has an installation effect when its width W is 0.03 mm or more. Also,
If the width is too large, the powder filled in the space in the vicinity of the flat land forming portion is difficult to solidify, so the upper limit is preferably about 0.5 mm. If the width W is 0.05 mm or more, the effect of preventing the biting of the powder is sufficiently exerted, and if the width W is 0.2 mm or less, the compressibility of the powder is not adversely affected.

  In addition, in the flat land, a surface that intersects at a right angle is more preferable than a surface that intersects at an obtuse angle with respect to the sliding surface with the second mold because the effect of preventing the biting of the powder is high. A surface that intersects the sliding surface with the second mold at an acute angle is not preferable because a sharp edge that is weak in strength is generated between the surface and the sliding surface.

  In the sintered part manufactured using the powder molding die of the present invention, the sliding surfaces of the first die and the second die are protected by the effect of preventing the biting of the powder. The surface (molded surface) is less damaged and has excellent surface properties.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a powder molding die according to the present invention will be described below with reference to FIGS. The powder molding die shown in FIG. 1 is obtained by adding the features of the present invention to the model described in FIG. 8, and includes a basic element die 1, a lower punch 2, and an upper punch 3. Here, the die 1 is the first mold referred to in the present invention, and the lower punch 2 is the second mold.

  In the stepped molding hole 5 of the die 1, a molding surface 5 a that pressurizes the powder in the cavity 6 in the axial direction, and a sliding surface (inner peripheral surface of the small diameter hole portion) 5 b between the molding surface 5 a and the lower punch, An R surface 5c that rounds the corners intersecting with each other is provided, and a flat land 9 that protrudes toward the lower punch 2 is provided at the lower end of the R surface 5c (the boundary between the R surface 5c and the sliding surface 5b). . The flat land 9 is a surface perpendicular to the axis (a surface intersecting at right angles to the sliding surface 5b), and its width W (FIG. 2) is set to 0.03 to 0.5 mm which is preferable. Yes.

  When the powder molding die shown in FIG. 1 is used, the flat land 9 provided on the die 1 causes the flat space shown in FIG. A bottom surface is created, and the powder that has entered the space 8 is received by the bottom surface. Thereby, the dragging of the powder into the sliding gap between the die 1 and the lower punch 2 is prevented, and the biting of the powder and the resulting damage to the mold forming surface are prevented.

  As shown in FIG. 3, the green compact 10A molded by the powder molding die in FIG. 1 has a corner formed by the side surface 12 and the end surface 11 of the convex portion 13 at the corner surface Rc 5c. It has the shape | molded R surface 14, and also has the flat surface 15 shape | molded by the flat land 9 of the formation hole in the boundary part of the R surface 14 and the side surface 12. The green compact 10A is sintered to obtain a sintered part of the present invention. The sintered part has less surface roughness due to scratches on the molding surface and is excellent in surface properties.

  4 to 6 show other embodiments of the powder molding die of the present invention. This powder molding die is used for molding a gear with a boss (gear incorporated in an engine drive system) 30 shown in FIG. 7, and includes a die 1, a lower punch 2, an upper punch 3, It consists of a core rod 4. On the inner surface of the straight forming hole 5A provided in the die 1, teeth and tooth grooves for forming the gear portion are provided.

The lower punch 2 is divided into two parts, a lower 1 punch _2-1 and a lower 2 punch _2-2 . Each of the upper punch 3, the lower 1, and the lower 2 punches 2 ₋₁ , _2-2 has a cylindrical shape. Further, on the outer periphery of the lower lower punch _{2-1 and} the outer periphery of the upper punch 3, groove teeth and teeth that fit and mesh with teeth on the inner surface of the forming hole of the die 1 are provided.

The 4-6 powder molding die is first divided body of the lower punch (which figure below 1 punch 2 _-
1 ) is the first mold referred to in the present invention, and the second divided body of the lower punch (lower 2 punch _2-2 ) is the second mold referred to in the present invention.

  The gear 30 with a boss in FIG. 7 has a boss portion 32 having a shaft hole on one end side of the main body portion 31.

Under 1 punch 2 _-1 shaping the end face 33 of the main body portion 31 surrounding around the base of the boss, also under 2 punch 2 _-2, forming the tip end of the boss portion 32.

The lower 1 punch _2-1 is formed at the intersection of the upper surface 2a (corresponding to the molding surface 5a) and the inner peripheral surface (sliding surface with the lower 2 punch) 2b for forming the end surface 33 of the main body 31. It has an R surface 5c that gently connects two surfaces that form a right angle, and a width W (FIG. 6) is 0.03 to 0.03 at the lower end of the R surface 5c, that is, at the boundary with the inner peripheral surface 2b. Flat lands 9 each having a range of 5 mm are provided. With the mold of FIGS. 4 to 6, the space 8 of Subomi below is formed between the lower 1 punch 2 _-1 and lower two punch 2 _-2 in the state of FIG. 5, the powder in the space 8 The powder is received by the flat land 9 when it falls. Accordingly, even in this molding die, the biting of the powder into the sliding gap is prevented.

  As described above, there is a mold in which one of the divided parts of the lower punch is formed with an R surface or an inclined surface that causes powder to enter the sliding gap. A divided body having a first die is provided with a flat land characterizing the present invention.

  The boss-equipped gear 30 shown in FIG. 7 manufactured by molding with the mold shown in FIGS. 4 to 6 is a flat surface formed by the flat land 9 at the boundary between the end surface 33 and the outer peripheral surface of the boss portion 32. 15 is formed.

  Further, the present invention is effective even when applied to a mold in which the R surface 5c of each embodiment is replaced with a chamfered surface of an inclined surface.

Sectional drawing which shows 1st Embodiment of the powder molding die of this invention Sectional drawing which expands and shows the principal part of the powder molding die of FIG. 1 is a perspective view of a sintered part manufactured by molding with the powder molding die of FIG. Sectional drawing which shows 2nd Embodiment in a compression completion state Sectional drawing which shows the green compact extrusion state of the powder molding die of FIG. Sectional drawing which expands and shows the principal part of the powder molding die of FIG. Sectional view of a bossed gear produced by molding with the powder molding die of FIG. Sectional view showing a model for explaining the problem of a powder mold FIG. 8 is a perspective view of a sintered part produced by molding with the powder mold shown in FIG. Process diagram of powder molding by the powder molding die of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Die 2 Lower punch 2a Upper surface 2b Inner peripheral surface 2 _-1 Lower 1 punch 2 _-2 Lower 2 punch 3 Upper punch 4 Core rod 5 Stepped molding hole 5A Molding hole 5a Molding surface 5b Sliding surface 5c R surface or slope 6 Cavity 7 Powdering box 8 Space 9 Flat land 10 Sintered part 10A Compact 11 End face 12 Side face 13 Convex part 14 R face 15 Flat face 30 Boss gear 31 Main body part 32 Boss part 33 End face P Powder

Claims (6)

In the process of forming the green compact, it has a first mold and a second mold that are in contact with each other and move relatively in the axial direction, and the first mold pressurizes the powder in the cavity (6) in the axial direction. A mold having an R surface or a slope (5c) at a corner where the molding surface (5a) and the sliding surface (5b) of the second mold intersect, and including the first mold and the second mold In a powder molding mold in which the cavity (6) is created by:
A powder molding die, wherein a flat land (9) protruding from the R surface or the inclined surface (5c) toward the second die side is formed on the first die.   The powder molding die of Claim 1 which set the width W of the said flat land (9) to the range of 0.03-0.5 mm.   The powder molding die according to claim 1 or 2, wherein the flat land (9) is formed as a surface intersecting at right angles to the sliding surface (5b) with the second die.   The powder mold according to any one of claims 1 to 3, wherein the first mold is a die (1) having a stepped molding hole (5), and the second mold is a lower punch (2). .   The said 1st metal mold | die is a 1st division body of the lower punch (2) divided | segmented into plurality, The said 2nd metal mold | die is a 2nd division body of the said lower punch (2). The powder molding die in any one. A sintered part produced by sintering a green compact molded with the powder molding die according to any one of claims 1 to 5, wherein the end face (11) stepped down in the axial direction and the axial center And an R surface or an inclined surface (14) formed by the R surface or the inclined surface of the first mold, and the R surface or the inclined surface (14) and the above described Sintered part provided with the flat surface (15) shape | molded by the said flat land (9) of a 1st metal mold | die in a boundary part with a side surface (12).

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