JPS5945135A - Evacuation of mold to vacuum - Google Patents

Abstract

PURPOSE:To stably and effectively evacuate molds to vacuum at low cost by a method in which solenoid switching valves are provided to a cavity side and vacuum pump side ports of a tank leading to the vacuum pump in the exhaust pipeline of the mold cavity, and a branched pipe leading to the atmospheric pressure is provided through a solenoid switching valve between the cavity and the solenoid switching valve. CONSTITUTION:When the internal pressure of a tank 16 reaches a given pressure, it is detected by a pressure switch 19, a timer 35 begins to count by the operation of the pressure switch 19, A-contact 1TR1 is connected, and the timer 35 is self-holded. Since the pipeline is opened at the same time, a cavity 12 is connected with the tank 16, and the air, etc., of the cavity 12 is sucked into the tank 16. When the evacuating operation is ended, a vacuum pumps 14 begins to operate and the tank 16 is again evacuated. On the other hand, when time set to an injection-operating timer 38 by the time-out signal of the timer 35 is suspended, a carrying timer 41 begins to operate, the pipeline 20 is opened by the time- out signal of a carrying time relay 41, and the cavity 12 is led to the open air.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for evacuation of a mold used in injection molding, in which the cavity is filled with a bath melt resin after all the air inside the mold cavity is evacuated during injection molding.

Prevention of air entrainment into molded products during high-speed injection molding, removal of insert parts such as water caps during insert 1 and molding, precision molding with sharp parts on ζ etc. Mold clamping Exhaust the air inside the mold cavity and the mold cavity 1. A method is adopted in which the molten resin is then filled.

Conventionally, as shown in Japanese Patent Publication No. 19734/1973 in Fig. 1, a conduit 5 corresponding to opening/closing:l'P4 was installed in the cavity 3 formed by the fixed mold 1 and the movable mold 2 during injection molding. Insertion [2. Attach the vacuum pump 6 to the same pipe line 5 and exhaust air etc. from the cavity 3.1.

was. Therefore, when increasing the molding cycle, the cavity 3 must be vented quickly, sometimes instantaneously, so a relatively large capacity vacuum pump is required.
2) It was expensive.

When opening the mold after broken molding: There may be negative pressure inside the cavity, so the mold may not open smoothly, or the interlock may be malfunctioning, resulting in light leakage. There were problems such as continued vacuuming even after entering the pressure holding process.

The purpose of this invention is to eliminate the drawbacks mentioned in AiJ, provide an inexpensive, efficient, and stable method for vacuuming a mold.

Next, one embodiment of the present invention will be explained with reference to FIG. 2 and FIGS. A cavity 12 is formed. 1; (is a 1-tube airway for removing air etc. from inside the cavity, and the drive motor 14
It communicates with a vacuum pump 15 driven by. The exhaust front tread 13 has 1, J which communicates with the front exhaust cavity 1 rule.
] 6 a communicates with the vacuum pump “side V” 6 bf
A tank 16 having respective openings 16a and ] is provided.
61) City valves 17 and 18 that open and close are provided.

19 is the pressure inside the tank 16 J:II 17.1
The VC is open to the atmosphere during the g2 branch.
Explaining the expanded connection diagram in Figure 3, which was set up and deleted by n, 3] is the A contact at 1 loop for the vacuum pump] 5's 1 drive motor] 4's control i4]; Same score 31・
1 is 18 lunoids and is excited at the same time as the operation of mI 1-3]. 33 is a changeover switch, which switches the entire circuit so that the vacuum suction device according to the present invention operates automatically;
There is a contact 33a. 34 is a true redundancy relay that controls whether the vacuum in the tank 16 is completed or not, and has A contacts 34a, 34a3, and B contacts 341)2. 35
is the vacuum timer and the A contact ] 1” R, and ] T
R3a contact] 'I' R2, communicates the inside of the tank 16 with the cavity 12, sets a time period for sucking all the air, etc. in the cavity 12 into the tank 16, and also sets a timer for setting the time of the injection operation.'', 38 It operates. 39 is vacuumed! 12 so that the vacuum from the mold gear biner 412 is now drawn for the time set by the timer 35 and the timer 39. Here, the evacuation time is set separately for the timers 35 and 39, but of course one timer is sufficient, and in this embodiment, the timer 38 is used as an operation start signal for the timer 38 of the injection operation. Each timer tMep = 38.39 VC
There are f'TI, friend contact point Kujingan, 2TR, and 3TR.

/IO is type 1■ 7If the pressure of Nonda rises at a predetermined pressure level [, whether k 1li
ll i'1lilf When the pressure rises to 1, 41 breaks contact 4TR with the timer set to the chiring timer.

The control@1 circuit is as described above, and its effect 4 is as follows.
To explain IIIi, first, the inside of the mold is drained and the vacuum pump is removed]5. When the relay 31 of the driving motor 4 is activated and the A contact 312 is connected, the motor 4 starts driving. Air, etc. is sucked from inside the tank 16, and when the inside of the tank 16 reaches a predetermined pressure, the pressure switch 19 detects L, and the signal is activated]~, and the mamoki completion relay 371 starts operating, and the evacuation, which will be described later, starts. The operation relay 36 is also activated, and the vacuum relay 34 is self-held. On the other hand, mold clamping has completed I2,
The moving tie plate 10 has been moved by forward growth, and 6
- Open in the pressure increase circuit ++ s Soto Suinochi LS2
The connection is open and the pressure rises to 1.40. ing. Aj? The timer is activated by the operation of the pressure cutter 19 as described above:
(Start 5 Pubatsu J Uno l- 17, A contact I TR1 is connected and opened, so cavity 12 and tank 161! m
Then, the air, air, etc. in the cavity 12 are sucked into the tank 16, that is, the true drawing action 1'F of the cavity 12 is performed, and when the relay 36 is activated and a predetermined time elapses, the A contact I T Rl and l i” R3 open,
B contact 11' R2 is connected and timers 39 and 38
starts to operate. Even after the timer 35 expires, the circuit is held by the A contacts 2TR and VC of the timer 39, so the vacuuming operation is interrupted and continues for the time set in the timers 35 and 39. . mT When the vacuum suction operation is completed, that is, when the timer 39 counts out, the vacuum suction operation relay; ) At 2, the vacuum pump 14 starts full operation (and the suction inside the tank 16 is performed).

- 10,000, activated by the timeout signal of the timer 35
．． Set the injection operation time to 38 1. When the time has expired, the A contact 3 TR is connected, the nog timer 41 (gear 1 where counting and cooling is performed) starts operating, the human contact 4 'I' R is connected, and the relay α path 2 f ) is opened, and the cavity]2 is communicated with the atmosphere, and the mold pressure is increased to 1J mocha (1J
This eliminates the conventional disadvantage of creating a negative pressure inside the die rearward feeding cavity. is exposed to the atmosphere, so that the movable die plate 10 can smoothly retreat when the mold is opened, and B of the filling process completion relay during the injection operation, which is not shown in the vacuum operation circuit.
Since the contact 431) is provided, the relay is activated after the filling process is completed j7], and then the H operation 1. An interlock is provided so that the evacuation operation is completed on the premise that the filling process is completed. Therefore, during injection, a full vacuum operation is performed to prevent resin from entering the suction hole.

As explained above [7], the method of the present invention can significantly lower l1fIi compared to conventional equipment, and the mold opening/closing operation can be performed reliably, so that the molding operation can be performed stably. I can do it.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional method. FIG. 2 is a diagram illustrating one implementation according to the present invention. FIG. 3 is a diagram C showing one restraining circuit according to the present invention. 11...gold"l, 12...cavity, 13...
Exhaust pipe line, 15... Nitrogen pump, 16... Tank,
17,] 8.20...Solenoid valve, 19...Pressure valve
Sochi. Applicant: Toshiba Machine Corporation 9-

Claims (1)

[Claims] 1. After completion of the mold clamping process, all air, etc. in the cavity is exhausted [
1. A tank that communicates with a vacuum pump to an exhaust pipe line for exhausting air from the inside of the mold cavity in a mold evacuation method used for a vacuum injection bottom shape in which molten resin is injection molded into the cavity; The cavity side entrance of the same tank and x
Each of the exhaust pipes communicating with the side ports of the two pumps is provided with a branch pipe that connects to atmospheric pressure by opening and closing the inner pipe. 111111 'f path' 5 [1], the cavity is triggered l'I, and after the evacuation is completed, the cavity side pipe is completely closed, and the branch pipe communicating with the atmosphere is opened, 1. How to vacuum the mold to make it work on the previous D-V. A method for evacuation of a mold according to claim 1, characterized in that the evacuation is completed by the time the mold cavity is opened. 1. When lowering the mold clamping pressure and opening the mold at low speed,
The mold evacuation method according to Claims 1 and 2, characterized in that the branch pipe communicating with the atmospheric pressure is opened to the atmosphere.