JPS58119500A - Controlling method of powder compacting machine - Google Patents

Abstract

PURPOSE:To prevent the generation of cracks, etc. by moving the position of a compact with one of punches even during the stage of pressurizing. CONSTITUTION:When a powder supplying stage is completed, an upper punch is moved downward and a lower punch is moved upward whereby the powder is preliminarily pressurized. Thereafter, the pressurizing stage is started by moving the upper punch at a low speed. On the other hand, the lower punch is changed over from position control to pressure control and the pressurizing pressure of the lower punch is controlled to a prescribed value. Therefore, the lower punch is moved upward in follow up to the upward movement of the upper punch, and during this time, the powder sandwiched by both punches is compacted by the pressurizing force of the lower punch. Upon ending of the pressurizing stage, the upper punch is moved upward at the speed lower than the speed in the stage of pressurizing, and the lower punch is subjected to the pressure control in such a way that the pressurizing force thereof is controlled to the hold-down pressure smaller than the pressure in the pressurizing stage. In such a way, the compact is ejected while moderate pressure is exerted upon the compact.

Description

[Detailed description of the invention] The present invention relates to a method for controlling a powder compacting machine.

Generally, in a powder compacting machine, powder filled in a die mounted on a tie table is compressed into a predetermined shape by an upper punch driven by an upper hydraulic device and a lower punch driven by a lower hydraulic device. After forming a molded body, the upper punch is moved upward, and the lower punch is moved upward until it is flush with the top surface of the die table, so that the molded body is positioned flush with the top surface of the die table. Then, the molded body is discharged by a dispensing device.

However, in such a device, in the pressurizing process,
When the punch is stationary and then moves to the first extrusion step, the molded product suddenly starts moving, which can cause surface defects such as cracks on the molded product. There are problems such as the molded product expanding rapidly during single extrusion, which may cause cracks and the like.

In view of these points, the present invention reduces the frictional force generated between the molded body and the die, suppresses the rapid expansion of the molded body during extrusion, and prevents the occurrence of cracks, etc., which are surface defects of the molded body. An object of the present invention is to provide a method for controlling a powder compacting machine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

The diagram shows time on the horizontal axis and displacement and pressure on the vertical axis, and shows the control status of the displacement and pressure of the upper batch and lower punch. The upper punch, which had been lifted, is lowered, while the lower punch is moved upwards shortly after the upper punch starts lowering, and the powder is preliminarily pressed by both punches.

When the pre-pressing step is completed in this manner, the upper punch is moved upward at a slow speed to proceed to the pressurizing step. On the other hand, when the preliminary pressurizing step is completed, the control of the lower punch is switched to the position control @force/pressure control, and the pressurizing pressure of the lower punch is controlled to a predetermined value. Therefore, the lower punch moves upward following the upward movement of the upper punch, and during this time, the powder held between both punches is compressed to a predetermined pressure by the pressing force of the lower punch, and the powder is molded.

When the above pressurizing process is completed, the upper punch is moved upward at a faster speed than during the pressurizing process - and at the same time, the lower punch is pressed so that its pressurizing force becomes a smaller hold-down pressure than during the pressurizing process. controlled. With this force, the lower punch moves upward following the upper punch while applying holddown/pressure to the compact. When the molded body is extruded onto the surface of the die table, the movement of the lower punch is stopped and the upper punch continues to move upward, after which the molded body is discharged.

By the way, in the above example, the lower punch was switched to pressure control during the pressurization process and the extrusion process, but the control of the upper punch was switched to pressure control during both of the above processes, and the upper punch was used to form the mold. In addition to controlling the pressure applied to the body, the movement of the molded body may be controlled by the lower punch.

1. During the pressurization process, the lower punch controls the pressure and the upper punch controls the position. During the extrusion process, the upper punch controls the pressure and the lower punch controls the position, and the upper punch controls the hold-down pressure to control the molded product. You may also add it to

As explained above, in the present invention, even during the pressurizing process, the position of the molded body is moved by one of the punches, so that the molded body, which was stationary at the start of the extrusion process, is suddenly moved. There is no chance that you will be disappointed.
It is possible to reduce the frictional force generated between the molded body and the die. Further, even during the extrusion process, hold-down pressure is applied to the molded body by force and one of the punches, so that rapid expansion of the molded body is suppressed.

Therefore, it is possible to prevent the occurrence of surface defects such as cracks on the molded product at the start of the extrusion process and the like.

[Brief explanation of drawings]

The drawings are explanatory diagrams showing displacements of the upper cinch and lower punch and changes in pressure of one -ζ punch during each process in the present invention. Applicant's agent Kiyoshi Inomata Continued from page 1 0 Inventor Jo Sugimoto 2-3-1 Yokosuka City 539 Nippon Nuclear Tsuyuel Co., Ltd.

Claims (1)

[Claims] In a control method for a powder molding machine in which the upper and lower punches are each driven by a hydraulic device, the pressure process force is continuously controlled so that both the upper and lower punches do not come to rest when the extrusion process is completed. In addition to controlling
A powder molding machine characterized in that in the extrusion process, either the upper punch or the lower punch driving hydraulic device is in a pressure controlled state, and the molded product is extruded while applying an appropriate pressure to the molded product. Control method.