JPS63286502A - Compacting method for sintering compact - Google Patents

Abstract

PURPOSE:To take out a green compact having chamfering part without any damages of the green compact and a punch by promoting expansion of the green compact while descending a lower die after compacting, taking out the green compact from the die and next, ascending the lower die again. CONSTITUTION:After forming the green compact W1 under compressing, an upper punch 3 is ascended and the lower die 1 is descended to the standard position. In the green compact W1, the chamfering part W2 is formed at outer circumference of lower face by edge part 5 of recessed part 4 in the lower punch 3. Further, the lower die 1 is descended to relax the restriction caused by the die to the chamfering part W2 of the green compact W1. The green compact W1 is expanded toward diameter direction, and lifted upward and removed from the recessed part 4. Next, the lower die 1 is ascended, so that a lower punch 3 is inserted into a cavity 2 and after laying the green compact W1 on the upper face of the lower die 1, the take-out operation is executed. By this method, the yield of the green compact having chamfering part is improved and the service life and durability of the lower punch 3 are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for powder compacting a sintered molded product, particularly a sintered molded product having a chamfered portion.

(Prior art) Powder compaction performed before sintering of a sintered product is as shown in FIGS. A cavity 53 is formed and the raw material powder W is filled into the cavity 53 on the lower punch 52 (Fig. 8), and then the upper bunch 54 is lowered to pressurize the raw material powder W1 (Fig. 9), and after molding. The lower die 51 is moved down so that the upper surfaces of the lower bunch 52 and the lower die 51 are flush with each other (FIG. 10), and the molded product W1 is discharged (FIG. 11).

(Problem to be solved by the invention) By the way, if the powder molded product has a chamfered part, that is, the 12th
As shown in the figure, a female tapered recess 15 is formed on the upper surface of a lower bunch 152 that fits into a lower die 151 to form a cavity 153.
2a is formed, and the peripheral part of the recess 152a is radially outward and upward in a ring-shaped edge (152b), the upper surface 151 of the lower die 151 and the upper end bin angle a of the edge 152b of the lower punch 152 At position A on the same plane, the outer periphery of the lower surface of molded product W1 is chamfered W2 to form a tapered shape. There is a risk of interference and damaging the molded product or damaging the pin angle a.

On the other hand, when the lower die 151 is lowered to position B, the molded product W1 expands, but since there is a distance between the pin angle a of the lower punch 152 and the upper surface 151a of the lower die 151, the chamfered portion of the pin angle 81 is removed during dispensing. W2 interferes and damages one or both.

On the other hand, even if the lower die 151 is raised to position C, the molded product W1 is caught between the lower die 151 and cannot be discharged.

The present invention was made in order to solve the above-mentioned problems in discharging a powder-molded product with a chamfer from a powder-forming press. The purpose is to enable the punch to be ejected without damaging it, thereby improving the lifespan and durability of the molding device and improving the yield of molded products.

(Means for solving the problem) The method for solving the above problem is to lower the lower die to the reference position after compaction, and then repeat the procedure until the compact is completely removed from the lower die. A step of lowering the powder molded product to promote expansion and releasing the molded product from the lower bunch, and then raising the lower die again to place the powder molded product on the upper surface of the lower bunch, and then releasing the molded product from the lower bunch. It consists of a step of dispensing.

(Operation by the above means) According to the above means, since the lower die is lowered below the reference plane after forming, the molded product on the lower punch is released from the restraint by the cavity of the die, expands, and separates from the upper surface of the lower punch. The molded product expanded by the subsequent rise of the lower die is supported on the upper surface of the upper peripheral edge of the cavity of the lower die, so that the chamfered part is not damaged during dispensing, and the punch does not interfere with the molded product.

(Embodiment) Next, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 to 5 are diagrams showing the method of the present invention in the order of steps, and FIG. 6 is an enlarged view of the main part of FIG. 5.

In the figure, reference numeral 1 denotes a lower die, and a part of the die is provided with a cavity 2 that passes through the die vertically, and a lower punch 3 is fitted into the cavity 2 so as to be slidable therein. The lower punch 3 has an acid-tapered recess 4 formed on its upper surface, and an edge 5 inclined upward and radially is formed around the recess 4, and a pin corner 6 at the tip of the edge 5 and a lower It is on the same plane as the upper surface 1a of the die 1 at the reference position.

The lower punch 3 is fixed, the lower die 1 is raised, and the lower punch 3
The cavity 2 formed above is filled with raw material powder W.

This is shown in Figure 1.

Next, the upper punch 7, which is concentric with the lower bunch 3 and faces upward, is depressed, and the upper punch 7 is fitted into the cavity 2, and the raw material powder W
is pressure-molded to obtain a compacted powder product W1. This is shown in FIG. 2. After forming, the upper punch is raised 112, and then the lower die is lowered to the reference position. This is shown in Figure 3. In the obtained molded product W1, a chamfered portion W2 is formed on the outer periphery of the lower surface at the edge portion 5 of the recessed portion 4 of the lower bunch 3.

As described above, the upper punch 7 is raised, the lower die 1 is lowered to the reference position, and then the lower die 1 is further lowered. As a result, the upper end of the upper bunch 3 protrudes above the upper surface 1a of the lower die 1. As a result, the chamfered portion W of the molded product W1
2 is released from the restraint by the die 1, the molded product W1 expands in the radial direction, and is lifted upward because the chamfered portion W2 is tapered and the edge portion 5 of the lower bunch 3 is tapered.
The molded product W1 will be separated from the recess 4. As a result of the expansion of the molded product W1, the diameter of the molded product W1 becomes larger than the inner diameter of the cavity 2 of the lower die 1 by Δr.

Next, the lower die 1 is raised again until the lower punch 3 is recessed into the cavity 2. As a result, the molded product W1 on the lower bunch 3 has a chamfered portion W' on the upper edge of the cavity 2 of the lower die 1.
2 is caught and supported, and cavity 2
The upper edge 2a is not an acute angle like the bottle corner 6 of the lower bunch 3, and the chamfer W2 is tapered, so even if it is moved in the direction of the arrow, it can be moved smoothly without damaging the chamfer W2. Therefore, the molded product can be ejected without damaging the molded product, and since the lower punch 3 is recessed into the lower die 1, the edge portion 6 and the molded product W! Therefore, the lower punch 3 will not be damaged by dispensing the molded product.

In FIGS. 5 and 6, the amount of bulge Δr of the molded product w1 is shown in a large size for convenience of explanation, but in reality it is approximately o, about 15 mm.

(Effects of the Invention) As is clear from the above, according to the present invention, after compaction between the upper and lower punches and the die, the lower die is lowered from the reference plane, so the molded product on the lower punch is released from the restraint of the die. It swells and expands;
The molded product, which is separated from the upper surface of the lower punch and expands as the lower die rises, is supported by the upper surface of the upper periphery of the upper end of the cavity of the lower die.
Therefore, the chamfered part is not damaged when the molded product is ejected from the upper surface of the lower die by the groove direction, and the yield of the chamfered molded product can be improved, and the lower punch does not interfere with the molded product. Since there is no damage, the life and durability of the lower punch is improved.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention. Fig. 1 shows the filling of the raw material powder, Fig. 2 shows the compacting process, Fig. 3 shows the completed forming process, and Fig. 4 shows the lower die descending. Figure 5 is a diagram of the lower die rising, Figure 6 is an enlarged view of the main part of Figure 5, Figures 7 to 11 are explanatory diagrams showing the conventional compaction process, and Figure 12 is the conventional FIG. In the drawings, 1 is a lower die, 2 is a cavity, 3 is a lower punch, 7 is an upper die, and Wl is a molded product.

Claims (1)

[Claims] After compaction, the lower die is lowered to the reference position, and then lowered again until the powder molded product is completely removed from the lower die to promote expansion of the powder molded product and release the molded product from the lower punch. A method for powder compacting a sintered product, the method comprising the steps of: raising the lower die again, placing the compacted product on the upper surface of the lower die, and then discharging the compacted product. .