JP2926686B2 - Powder molding equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder molding apparatus that fills a cavity with a raw material powder such as a metal powder and pressurizes in this state to form a product.

2. Description of the Related Art In powder molding for producing a green compact by pressing a raw material powder, a small through hole may be formed simultaneously with the outer surface. Conventionally, in such a case, a powder molding apparatus as shown in FIG. 5 has been used.

The powder molding apparatus shown in FIG. 1 includes a die 2 having a molding hole 1, an upper punch 3 and a lower punch 4 which are fitted into the molding hole 1 and pressurize the raw material powder A filled in the molding hole 1 from above and below. And a core 5 and a hole forming pin 6 that penetrate the lower punch 4 and can move up and down with respect to the lower punch 4. The upper end of the core 5 and the hole forming pin 6 is fitted into the upper punch 3. Escape holes 7, 8 are formed as much as possible. In addition, 9 in the figure
This is a cavity formed by the forming hole 1 of the die 2 and the upper surface of the lower punch 4. When the green compact is manufactured, the raw material powder A is filled into the cavity 9 in a state where the molding hole 1 of the die 2 and the lower punch 4 are fitted.
The upper punch 3 is fitted into the molding hole 1 and the raw material powder A is pressed to form a green compact. Finally, after the pressing of the upper punch 3 is released, the die 2, the core 5 and the hole forming pin 6 are removed. The core 5 and the hole forming pin 6 are pulled out from the green compact at the same time as the green compact is taken out from the molding hole 1 by lowering.

This similar structure is disclosed in, for example, Japanese Utility Model Laid-Open No. 61-147227.

Problems to be Solved by the Invention When the green compact is taken out from the molding hole 1 of the die 2, it tends to expand in the outer shape direction due to its own springback. For this reason, in the above-mentioned powder molding apparatus, when the green compact is taken out from the molding hole 1, the hole forming pin 6 is pushed outward by the springback of the green compact, and the green compact is formed from the green compact. At the moment when the pin 6 is pulled out, as shown in FIG. 6 (the compact is indicated by W), the tip of the hole forming pin 6 makes the edge corner 10a of the hole 10 of the compact W strong by the spring back. Pressing may cause cracks or breakage there.

Accordingly, an object of the present invention is to provide a powder molding apparatus capable of producing a high-quality green compact by preventing cracks, breakage, and the like from occurring in the green compact at the time of extracting the molding pin.

Means for Solving the Problems The present invention, as means for solving the above-mentioned problems,
A die having a molding hole for shaping the outer peripheral surface of the green compact, upper and lower punches fitted into the molding hole of the die to press the raw material powder, and an axial direction along the molding hole of the die. A hole forming pin that is inserted to form a hole along the axial direction in the green compact, and the raw material powder is filled into a cavity formed by a die forming hole and a punch, and the green compact is pressed by the punch. After molding, the powder compact is extracted from the molding hole of the die, and then the hole molding pin is extracted from the green compact. A tapered step portion having a larger diameter is formed on the base side of the.

The tapered step that expands toward the base of the hole-forming pin is provided at the position facing the cavity of the hole-forming pin, so a similar tar-shaped step is also formed in the hole formed in the green compact. Became shaped. For this reason, when the green compact is pulled out from the molding hole of the die, the tip of the hole forming pin that is pushed out in the outer direction by the spring back of the green compact is pulled out of the green compact when the green compact is pulled out from the green compact. The edge of the hole is not easily chipped because it comes into contact with the tapered step formed in the hole.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. The same parts as those shown in FIGS. 5 and 6 are denoted by the same reference numerals.

In the drawings, reference numeral 2 denotes a die provided with a forming hole 1 and moved up and down by an actuator (not shown). Reference numeral 11 denotes a cylindrical lower fixed punch set on a fixed base (not shown).
A core 5 is formed on the inner peripheral side of the fixed lower punch 11 to form a large-diameter hole 12 at the center of the green compact W, and a cylindrical shape on the outer peripheral side is fitted into the forming hole 1 of the die 2. The floating lower punches 13 are respectively fitted to be able to move up and down.

A hole forming pin 15 is rigidly supported by the floating lower punch 13 so as to form a predetermined number of holes 14 having a small diameter at a predetermined position of the green compact W. The hole forming pin 15 has a tapered step 16 whose diameter is increased toward the base side (lower side) at a portion protruding from the upper surface of the floating lower punch 13 by a predetermined amount.

Reference numeral 3 denotes an upper punch which moves up and down by an actuator (not shown) and which fits into the forming hole 1 of the die 2 at the time of lowering. The upper punch 3 is provided with escape holes 7 and 8 into which the respective tips of the core 5 and the hole forming pin 15 can be fitted. Core 5 and hole forming pin 1
5 are to be inserted respectively.

In the drawing, reference numeral 17 denotes a step formed in the hole 14 of the green compact W by the step 16 of the hole forming pin 15, and 18 denotes a molding hole 1 of the die 2 and a fixed lower punch 11. Upper surface and floating lower punch 13
Is a cavity formed by the inner peripheral surface and the upper surface of the substrate.

In the above configuration, when the green compact W is manufactured, first, the core 5 and the floating lower punch 13 are raised together with the die 2 with respect to the fixed lower punch 11 as shown in FIG.
In this state, the compact 18 is filled in the cavity 18.

Then, from this state, the upper punch 3 is lowered as shown in FIG. 2, the upper punch 3 is fitted into the molding hole 1 of the die 2, and the raw material powder A in the cavity 18 is pressurized. During this time,
The core 5 and the hole forming pin 15 are fitted into the escape holes 7 and 8 of the upper punch 3, respectively. When the raw material powder A in the cavity 18 is pressurized in this way, a green compact W is formed, and a hole in the green compact W is formed.
Inside 14, a tapered step 17 is formed.

Subsequently, the green compact W thus formed is placed in the cavity.
After the upper punch 3 is raised to take it out of the die 18, the die 2 is lowered to the same height as the floating lower punch 13 as shown in FIG. Then, the floating lower punch 13 is lowered together with the die 2 to remove the minimum outer shape of the green compact W from the floating lower punch 13, and at the same time, the hole forming pin 15 is pulled out from the green compact W. When the maximum outer shape portion of the green compact W is pulled out from the die 2, the maximum outer shape portion of the green compact W expands in the outer shape direction due to its own springback, so that the hole forming pin 15 is elastically deformed by this. Therefore, when the molding pin 15 is pulled out of the green compact W, the tip of the molding pin 15 tends to be displaced by the springback so as to return to the center axis direction of the green compact W.

However, since the tapered step 17 is formed in the hole 14 of the green compact W as shown in FIG. 4, the tip of the hole forming pin 15 is not completely removed from the green compact W. At the step 17 in the hole 14, the green compact W is displaced in the central axis direction. Therefore, at the moment when the molding pin 15 is completely pulled out of the green compact W, a large displacement such that the tip of the molding pin 15 is directed toward the center axis of the green compact W is not observed. Further, when the hole forming pin 15 is displaced in the center axis direction of the green compact W inside the hole 14, the step 17 is formed in a tapered shape and is structurally strong, so that a crack around this portion is generated. No damage or damage.

Finally, after lowering the core 5, the green compact W is removed from the upper surface of the lower punch 4 to complete the manufacturing.

Advantageous Effects of the Invention As described above, according to the present invention, at a position facing the cavity of a molding pin, a tapered step portion having a diameter that is increased toward the base side of the molding pin is formed. The corresponding tapered step is formed in the inside, so that the tip of the hole forming pin pushed and expanded in the outer direction by the spring back of the green compact is structurally pulled out from the green compact. This makes contact with the tapered step portion in the hole which is strong in the compact, so that the problem of cracking, breakage and the like in the green compact does not occur. As a result, it is possible to produce a high-quality green compact without cracks or breakage.

[Brief description of the drawings]

FIGS. 1, 2, and 3 are cross-sectional views showing an embodiment of the present invention, FIG. 4 is an enlarged cross-sectional view corresponding to a portion IV in FIG. 3, FIG. The figure is an enlarged sectional view corresponding to the portion VI in FIG. 15 ... Hole forming pin, 16 ... Step. 18 ... Cavity.

Claims (1)

(57) [Claims] 1. A die having a molding hole for forming an outer peripheral surface of a green compact, upper and lower punches fitted into the molding hole of the die to pressurize raw material powder, and a die having a molding hole formed therein. A hole forming pin that is inserted along the axial direction to form a hole along the axial direction in the green compact, and the raw material powder is filled into the cavity formed by the forming hole of the die and the punch, and is added by the punch. After forming the green compact by pressing, the green compact is extracted from the molding hole of the die, and then the hole forming pin is extracted from the green compact. A powder molding apparatus characterized in that a tapered step portion is formed on the base side of the hole forming pin so as to expand in diameter.