JPS6236850B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mechanical press for forming plastics.

Plastic is heated and then molded in a mold, and immediately after molding, it must be held in the mold until it cools. The force required for this holding is much smaller than the force required for molding. (about
1/10 - 1/15) Previously, plastics were mainly molded using hydraulic presses, but a method was also considered that used a mechanical press and stopped for a period of time at bottom dead center.

However, hydraulic presses tend to have lower productivity than mechanical presses due to the number of strokes per minute. That is, since it takes a long time for the ram of the hydraulic press to descend, the heated material cools down, resulting in poor flow of the material and increased deformation resistance.

On the other hand, in a method that uses a mechanical press and stops at the bottom dead center, variations in the stopping position directly affect the dimensional accuracy of the product.Furthermore, since the brake is applied before the bottom dead center, the press required for processing is There are drawbacks such as the possibility of insufficient torque.

The present invention has been made to solve such problems. Hereinafter, an embodiment of the present invention will be explained in detail based on the drawings.

In FIG. 1, a hydraulic cylinder 9 is fixed to a slide 1 of a press, and a piston rod 11 of a piston 10 incorporated therein is fixed to an upper die plate 2.

The upper die 3 is fixed to the upper die plate 2. The lower die plate 4 is assembled to a press bolster 6, and the lower die 5 is fixed to the lower die plate 4 and faces the upper die 3. The guide 8 is fixed to the lower die plate 4, and the guide rod 7 fixed to the upper die plate 2 is inserted into the hole. The cylinder 21 for elevating the product is fixed to the bed of the press (not shown), and the piston rod 19 of the piston 20 installed inside the cylinder 21 is fixed to the bed of the press (not shown).
is fixed to the bar 18. Ejecta pin 1
7 is received by the bar 18, passes through holes in the lower die 5, the lower die plate 4, and the bolster 6, and reaches the upper surface of the lower die 5. The opening above the piston 10 of the fluid pressure cylinder 9 is connected to the discharge side of the pump 15, and a tank 16 is connected between this circuit and the tank 16.
An electromagnetic check valve 12 is provided which can be electrically controlled to open and close, and a pressure switch 14 which can adjust the pressure fluid to a required constant pressure is provided. Furthermore, between the opening on the lower side of the piston 10 of the fluid pressure cylinder 9 and the tank 16 side circuit of the electromagnetic check valve 12, there is provided an electromagnetic check valve 13 that is non-returnable toward the tank 16 and that can be electrically controlled to open and close. It is set up. The effect will be explained below.

(a) In FIG. 1, when the slide 1 is stopped at the top dead center, the material 22 is fed onto the lower die. At this time, the pump 15 is stopped, the electromagnetic check valve 12 is closed, and the electromagnetic check valve 13 is closed.

(b) In Figures 1 and 2, at the same time as the slide 1 starts descending, the electromagnetic check valve 1
Let's open 3. The molding is completed when the slide 1 reaches the bottom dead center.

(c) When the slide 1 rises after starting the pump 15, the pressure fluid discharged from the pump 15 flows into the upper side of the piston 10 and pushes the piston 10 down, and the pressure fluid below the piston 10 is opened. Check valve 13 to tank 16
Return to Due to these operations, the upper die 3 and the upper die plate 2 remain at the bottom dead center. Slide 1 stops at top dead center until the product cools down, and pump 15
The product 23 is held between the upper mold 3 and the lower mold 5 with a constant load by the action of the hydraulic cylinder 9.
(FIG. 3) The pressure of pressure oil supplied to the fluid pressure cylinder 9 is set by a pressure switch 14. This holding time is set by a timer.

(d) When the slide 1 is lowered again by the timer signal, the pump 15 is stopped and the electromagnetic check valve 12 is opened while the electromagnetic check valve 13 is kept open. Move to the side. At this time, the remaining fluid enters the tank 16.

(E) When the slide 1 reaches the bottom dead center, close the electromagnetic check valves 12 and 13 and move up.
Since the fluid under the piston 10 cannot flow out due to the check action of the electromagnetic check valve 13, the upper mold 3 and the upper mold die plate 2 are connected to the slide 1.
and then stop at top dead center.

(F) By the action of the product ejection cylinder 21, the product 23 is ejected via the piston rod 19, bar 18, and ejector pin 17.
(Figure 4) Hereafter, operations (a) to (f) are repeated.

Since the present invention has the above-described configuration, it is possible to provide a mechanical press for plastic molding with good product precision and high productivity.

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view, Figures 2 to 4 are explanatory diagrams of operation, 1 is a slide, 2 is an upper die plate, 3 is an upper die, 4 is a lower die plate, 5 is a lower die, and 6 is a Bolster, 7 is a guide rod, 8 is a guide, 9 is a fluid pressure cylinder, 10 is a piston, 11 is a piston rod, 12 is an electromagnetic check valve, 13 is an electromagnetic check valve, 14 is a pressure switch, 15 is a pump, 16 is Tank, 17 is ejecta pin,
18 is a bar, 19 is a piston rod, 20 is a piston, 21 is a cylinder, 22 is a raw material, and 23 is a product.

Claims (1)

[Claims] 1. In a mechanical press for molding plastics, there is a fluid pressure cylinder that is fixed downward to the slide of the press, an upper mold that is connected to the fluid pressure cylinder and can be raised and lowered, and a bolster of the press that faces the upper mold. A lower die provided in the lower die, a knockout means for pushing up the molded product from the lower die, and a tank and a circuit for sending pressurized fluid at a required pressure from a pump to an opening above the piston of the fluid pressure cylinder. , an electromagnetic check valve 12 that is non-returning toward the tank and can be electrically controlled to open and close; and an electromagnetic check valve 12 provided between the opening on the lower side of the piston of the fluid pressure cylinder and the tank side circuit of the electromagnetic check valve 12; 1. A plastic molding press characterized by comprising an electromagnetic check valve 13 which can be reverse-checked in the opposite direction and can be electrically controlled to open and close.