JPS6233281B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a powder compacting apparatus in which a die set includes a die, an upper punch, a lower punch, and a core rod having a stepped portion on the outer periphery.

With this type of molding apparatus, as shown in FIG. 1, a molded product b having a stepped portion a in the inner hole is obtained.
In this case, in order to maintain good formability at the base of the stepped portion a of the molded product b, it is generally necessary to increase the compression amount of the upper punch compared to the case of normal molding. The density of the upper part is higher than that of the lower part, which causes problems in terms of dimensional accuracy and physical properties after sintering.

This invention was made based on the above circumstances, and even if the pushing amount of the upper punch is large, the die plate is lowered in the compression stroke to balance the actual pushing amount of the upper punch and the lower punch, and the molding It is an object of the present invention to provide an improved powder compacting device in which the density of the product is approximately equal in the upper and lower directions.

Hereinafter, the present invention will be specifically explained based on illustrated embodiments. In the figure, reference numeral 1 denotes a base plate fixed to a press head 2, and a lower punch 3 is fixed to this. This lower punch 3
A core rod 4 penetrating through the inside has a stepped portion 4a formed on the outer periphery of its top, and is attached to a yoke plate 5 at its lower portion. An auxiliary plate 7 located above the base plate 1 is connected to the yoke plate 5 via a rod 6. In addition, the lower punch 3 and core rod 4
A die plate 9 forming a cavity 8 together with the top of the die plate 9 has a cylinder 10 and a piston 11 inside.
is installed inside the rod 12 of the piston 11.
is attached to the auxiliary plate 7. The cylinder 10 also has a compressed air inlet/outlet passage 1 on one side of its upper part.
3, and an air inlet/outlet hole 14 at the bottom. Further, an upper punch 15 that can be pushed into the cavity 8 is attached to an upper ram 16, and a timing pin 17 is provided on the upper ram 16. Further, a lower ram 18 is attached to the core rod 6 via the yoke plate 5.

In such a configuration, compressed air is introduced into the upper side of the cylinder 10 as shown in FIG.
The powder is filled into the cavity 8 with the powder floating, and the upper ram 16 is lowered and the upper punch 15
is pushed into the cavity 8 to compress and mold the powder. At this time, the timing pin 17 presses the die plate 9. With this, the cylinder 10
A compressive force is applied to the compressed air inside, and the die plate 9 descends while discharging a part of the air. At the final stage when the upper punch 15 is pushed in, the die plate 9
itself will be lowered, for example by a height H, as can be seen in the left-hand half of FIG. This has the same effect as pushing the lower punch 3 upwards by H within the cavity 8, so the molded product b formed in this way has approximately the same density on the upper and lower sides. Next, the upper ram 16 rises, the lower ram 18 descends, and the core rod 6 is pulled down as shown in the right half of FIG. It is exposed outside the cavity 8 in this state.

As described above, according to the present invention, in a die set in which a die, an upper punch, a lower punch, and a core rod having a stepped portion on the outer periphery are assembled, a cylinder and a piston are installed inside the die plate,
The die plate is floated before powder filling, and when the upper punch descends, the die plate is directly pressed down by the upper ram without using friction etc., and compression is performed by the punch. Even if the upper punch is pushed in a larger amount to form a stepped part, etc., the lower punch essentially pushes up and the upper and lower density can be made almost uniform, maintaining dimensional accuracy after sintering. This has the effect that the physical properties can be maintained in a desired state and the molded product will not be damaged. Further, it is possible to provide a powder compacting device that has a simple structure and can be downsized.

[Brief explanation of the drawing]

FIG. 1 is a partially vertical perspective view of a molded product according to the present invention, and FIGS. 2 and 3 are vertical cross-sectional side views for explaining the operating situation of one embodiment of the present invention. 3... Down punch, 4... Core rod, 4a...
Stepped portion, 8...Cavity, 9...Die plate,
10...Cylinder, 11...Piston, 15...
Upper punch, 16... Upper ram, 17... Timing pin, 18... Lower ram.

Claims (1)

[Scope of Claims] 1. A die set in which an upper punch, a lower punch, and a core rod with a step on the outer periphery are assembled, which are fixed to a die plate and an upper ram, and a cylinder and a piston are installed inside the die plate, Before powder filling, a fluid such as compressed air is introduced into the cylinder to float the die plate, and the upper punch is lowered and the timing pin attached to the upper ram pushes down the die plate, while the upper punch pumps the powder. A powder compacting device characterized in that it is configured to perform compression.