JPS6015099A - Die set for powder molding - Google Patents

Abstract

PURPOSE:To prevent the generation of a crack in a molding having an intricate shape by forming a lower punch of a die set for powder molding of plural constituting bodies and mounting an elastic body between the constituting body positioned on the outside thereof and a lower punch plate thereunder. CONSTITUTION:The 1st, 2nd, 3rd lower punch constituting bodies 11a, 11b, 11c attached at the bottom end respectively to lower punch plates 15, 16, 17 are laminated and fitted to form a lower punch 11. An elastic material 31 of urethane rubber, etc. is held via an adapter 32 between the body 11c on the outside and the plate 17. A gap (e) is preliminarily formed between the base 38 at the boss of the adapter 32 and the top surface 39 of the lower punch plate 17. Powder is packed in the space enclosed by the top plate of the lower punch 11 and the hole of the die in this state and the upper punch is lowered to compress to mold a molding W. When the upper punch is risen, the constituting body 11c is slightly moved by as much as the gap (e) to the upper punch side and therefore the generation of a crack in the molding W due to the popping up phenomenon is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a multi-layer structure having a step or a flange.
The present invention relates to a powder molding die set for compression molding powder into a shape.

FIG. 1 is a diagram showing an example of a molded product W manufactured by press-molding metal powder into a predetermined shape and then sintering. It has a complex shape with spline holes 2 on the surface and steps with different widths in the axial direction.

A powder molding die set conventionally used for compression molding such a molded product W is shown in FIG. 2.3. In addition, Figure 2 shows the completed state of compression molding, and Figure 3 shows the completed state of compression molding.
The figure shows the finished product for bales.

The die set 10 for powder molding is as shown in Fig. 2.3.
It has a lower punch 11, an upper punch 12, and a die 13.

The lower punch 11 is formed by stacking three cylindrical lower punch members 1'1a, 11b, and 11c together (1f), and the first lower punch member 11a is a lower punch member attached to the base 14. It is attached to the punch plate 15. 1st
A second lower punch structure 1 is provided on the outside of the lower bump structure 11a.
1b are twisted together, and this second lower punch structure 1''1b
is attached to the lower punch plate 16 attached to the base 14 fq
1 has been pressed. Third lower bunch structure 11 C1,tm
, 2 are fitted on the outside of the lower punch body 11b, and are attached to the lower punch plate 17 mounted on the base 14.

Teeth 18 are formed on the outer peripheral surface of the third lower punch structure 11c, similar to the external teeth 1 formed on the outer peripheral surface of the molded product W, and these 18 teeth have holes in which teeth 19 are formed to mesh with each other. 20 is attached to a die plate 21, and this die plate 21 has a rod 2 fixed thereto.
2, it is connected to the actuating plate 23. A core rod 24 whose lower end is viewed aA from the operating plate 23 is fitted into the hole 25 west of the first lower band 4v adult body 11a. A core 27 is provided with a spline 26 formed therein that meshes with the spline hole 2 .

An upper bunch 12 is attached to an upper punch holder 28 above the lower punch 11 and can be moved up and down, and teeth 29 that mesh with teeth 19 formed on the die 13 are formed on the outer peripheral surface of the upper bunch 12. At the same time, as shown in FIG. 3, a spline hole 30 is formed which engages with a spline 26 formed on the outer peripheral surface of the core. Further, the lower end surface of the upper bunch 12 has a stepped shape corresponding to the shape of the end surface of the molded product W. In addition, 15a is a cylinder that operates the lower punch structure 11a provided in the lower punch brakes 1 to 15, and 24a is a cylinder that operates the core rod 24 in order to improve mold release when pulling out the molded product W@pear. It is a cylinder that

In order to mold metal powder using such a die set 10 for powder molding, the space surrounded by the upper surface of the lower punch 11 and the hole of the die 13 is filled with powder, and then the upper bunch 12 is lowered. and compression mold the powder. To extract the molded product W formed in this manner, the upper bunch 12 is raised, and the operating plate 23 is lowered to remove the die 1.
3 and lower the core rod 24 against the die 13.
By raising the punch, the lower punch 11 is relatively raised.

However, when molding is performed using such a conventional die set 10 for powder molding, the three lower punch structures 1'1a to 11c, the first to third, have different lengths and are located on the center side. The first lower bunch structure 11 a lfi is the longest, and the length becomes shorter as the lower punch structures are located on the outer side. Even if the pressing force (stress) is applied almost uniformly, the amount of contraction in the axial direction of each of the lower punch structures 118 to 11C will be different. The longest first lower bunch structure 11a will contract the most. Therefore, when the upper bunch 12 is lifted to release the pressure applied to the lower punch 11 by the upper bunch 12, each lower punch structure 11
Since a to 110 extend back to their original state, the molded product W is pushed upward more by the first lower bunch structure 11a, and as shown in FIG. In some cases, cracks C were formed at the boundary between the central thin part 4 and the boss part 5.

For this reason, conventionally, when compression molding a molded product with a complicated shape such as a stepped shape as shown in FIG. In order to increase the strength of the molded product W, the molding work is carried out to increase the number of differences, or some extra thickness is unavoidably added to the molded product W in order to increase the strength of the molded product W.
Since that portion was removed by a process called "pudding" and later by "machining", there were problems in that the efficiency of the molding operation was poor and extra machining was required.

The present invention focuses on the problems of the prior art described above, and addresses the recent demand for molded products with complex shapes with many stepped parts, etc.
In order to meet expectations for chipless technology, the purpose of the present invention is to provide a die set for powder molding that can stably produce products without cracking even when molded products have complex shapes with many steps.

The structure of the present invention for achieving such an object is to form a lower punch by stacking and fitting together a plurality of cylindrical lower punch structures whose lower ends are respectively attached to the lower punch plate. A die having a hole into which the punch fits, and a die fitted into the hole and working together with the lower punch and the upper punch to compress and mold the powder. It is characterized in that an elastic body is installed between the lower punch structure located on the outside and the lower punch plate that supports the lower punch structure.

Hereinafter, one embodiment of the present invention will be described based on the drawings. Fig. 4 shows the state of compression molding by the Daicera 1- for powder molding of the present invention, and Fig. 5 shows the state of completion of extraction. As in the example, the first
This figure is for molding a molded product having the cross-sectional shape shown in the figure, and parts common to those shown in Figures 2 and 3 are designated by the same reference numerals.

Lower punch 11 of the powder molding die set of the illustrated embodiment
are the first to third lower punch structures 118 to 11c.
3 with different wall thicknesses among the molded products W shown in FIG.
The third lower punch structure 11C forming the outermost peripheral part 3 of the parts 5 to 5 is held by the lower punch plate 17 via an elastic body 31, for example, urethane rubber.

That is, the adapter 3 is attached to the lower surface of the third lower punch structure 11c.
This adapter 32 has a side wall portion 34 that fits into the boss portion 33 and the outer periphery of the lower punch plate 17.
and a flat part 35 connecting these parts, and the elastic body 31 is interposed between the flat part 35 of this adapter 32 and the lower punch plate 17. And adapter 32
The bottom surface 38 of the boss portion of the adapter 32 and the lower bunch plate 1.
The upper surface 39 of 7 forms a gap e, and the lower punch 9 can be moved slightly in the vertical direction by the gap e.

Further, the second lower punch structure 11b forming the central thin wall portion 4 of the molded product W is attached to the lower punch plate 1G, and the first lower band structure 11a forming the boss portion 5 is attached to the lower punch plate 15, respectively. 1. It is installed in the same way as shown in Figure 2.

Next, the effect will be explained. In FIG. 4, in the powder compression molding process, the upper punch 12 is lowered to the bottom dead center, and the third lower punch structure 11c receives pressure from the upper punch f-12, compresses the elastic body 31, and releases the adapter. -32 boss part bottom 3
8 is in close contact with the upper surface 39 of the lower punch plate 17.

In addition, the first lower bunch forming body 1'I a and the second lower punch forming body 11b are also compressed and deformed in the axial direction by receiving the pressing force from the upper punch 12, respectively. It is held by a bunch plate 16.

Next, when moving from the powder compression molding process to the molded product extraction process, the pressure from the upper punch 12 suddenly disappears, and each of the lower banded formed bodies 1'1a', 1 lb, and 11c returns to its original state. Stretch to. At this time, in order to reduce the phenomenon in which the molded product is pushed up toward the upper punch 12 side due to the release of the pressing force of the first lower punch structure 11a which has the largest amount of stretching, the bullet 11 body 31
Using the restoring force of the third lower punch structure 11c to move the third lower punch structure 11c toward the upper punch 12 side through the gap e, the fine movement V balances the elongation deformation of the first lower punch structure 11a. Gap e
is adjusted appropriately using the adjustment screw 37! It! can do. In this way, the deformation balance between the lower punch components is maintained, and cracks C do not occur in the molded product W due to the conventional molded product push-up phenomenon. Although the illustrated embodiment shows a lower punch with three lower punch structures, it is possible to embody the present invention in an embodiment having fewer or more lower punch structures. It is. In addition, the lower punch member to which the elastic body is attached may be provided on both the outermost lower punch member and the lower punch member immediately inside thereof, especially when there are a large number of these members.

As described above, according to the present invention, a plurality of cylindrical lower punch structures whose lower ends are respectively attached to the lower punch plate are stacked and fitted to form a lower punch, and the lower punch is fitted to the lower punch plate. In a powder molding die set that compresses and molds powder by fitting into the hole and working together with the lower bunch and the upper punch, the lower bunch located on the outer side of the plurality of lower bunch members Since an elastic body is installed between the punch structure and the lower punch plate that supports the lower punch structure, it is possible to prevent the upward movement of the lower punch into the molded product due to the difference in elongation between the lower punches during the molded product extraction process. can be prevented,
It is possible to stably produce parts with complex shapes with many steps without creating racks.

[Brief explanation of the drawing]

Figure 1 is a dimensional cross-sectional view of an example of a molded product, Figure 2 is a dimensional cross-sectional view of a conventional powder molding die set in a compression molding state, and Figure 3 is a dimensional cross-sectional view of an example of a molded product.
The figure is a cross-sectional view showing the state changed from the state shown in FIG. 2 to the complete extraction state, FIG. 4 is a cross-sectional view showing the compression molding state of a die set for powder molding according to an embodiment of the present invention, and FIG. is the fourth
FIG. 3 is a cross-sectional view showing a state changed from the state shown in the figure to a state in which extraction is completed. DESCRIPTION OF SYMBOLS 11...Lower bunch, 11a...1st lower punch structure, 11b...2nd lower bunch structure, 11c...3rd
Lower punch structure, 12... Upper punch, 13... Die, 15-17... Lower punch plate, 31... Elastic body, W... Molded product. Patent applicant: Nissan Motor Co., Ltd. No. 1-Fig. 2 G Fig. 2 Fig. 3 Fig. 4 Cause No. 5

Claims (1)

[Claims] A plurality of cylindrical lower punch structures each having a lower end attached to a lower punch plate are stacked and fitted to form a lower punch, and the lower punch is fitted into a die having a fitting hole and the die is fitted into the hole. 1. To the powder molding die cera 1 which compresses and molds powder by cooperation with the lower punch and the upper punch.
A die set for powder molding, characterized in that an elastic body is installed between a lower punch member located on the outer side of the plurality of lower punch members and a lower punch plate that supports the lower punch member. .