JPS644498Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improvement of a nozzle touch and a nozzle moving device of a stack mold injection molding machine or the like.

(Prior art and its problems) Conventionally, in this type of injection molding machine, the injection nozzle and the mold are separated when the mold is opened and closed for each shot, resulting in air intrusion into the molded product, uneven color of the molded product, sink marks, etc. We could not avoid the problems that tend to occur.

Therefore, as a measure to resolve this problem,
The present applicant has developed a method of controlling the hydraulic pressure of a nozzle touch hydraulic cylinder to keep the injection nozzle and mold in close contact with each other during the molding operation, and has already applied for this method (Japanese Patent Laid-Open No. 168538/1983). reference)
However, in this conventional method, the movement of the mold and the movement of the nozzle must be reliably matched, which requires precise and delicate hydraulic control, which increases production costs and
Because it is hydraulically operated, there were problems such as slow operation.

(Purpose of the invention) This invention was made to solve the above-mentioned conventional problems all at once.It allows accurate contact between the mold and the injection nozzle, simplifies cylinder control, and allows manufacturing at low cost. The purpose is to improve the quality of molded products.

(Structure of the invention) The nozzle touch and nozzle moving device for an injection molding machine according to the invention has one end attached to a fixed platen or a fixed frame, the other end attached to a plasticizing device, and connected to a hydraulic source via a switching valve. A hydraulic cylinder for the connected high-pressure nozzle touch, one end attached to a fixed frame or fixed platen, the other end attached to the plasticizing device, and connected to a pneumatic source via a switching valve for moving the plasticizing device. The injection nozzle and mold are always kept in close contact with each other by constant pneumatic pressure during the molding process, and are crimped by hydraulic pressure during the injection and pressure holding processes. shall be.

(Example) An example in which the present invention is applied to a stack mold injection molding machine will be described below with reference to the drawings.

In the figure, reference numeral 1 denotes a fixed platen fixed on a molding machine frame 2, and a fixed mold 3 is attached to the platen 1.

4 is a hydraulic cylinder 6 or a pneumatic cylinder 1 described later.
The plasticizing device 4 is movably mounted on a molding machine frame 2, and an injection nozzle 5 is attached to the tip of the device 4.

Reference numeral 6 denotes a hydraulic cylinder for high-pressure nozzle touch, which is attached to the fixed platen 1 at one end and to the plasticizing device 4 at the other end, and the cylinder 6 is connected to a hydraulic source 8 and a tank 9 via a switching valve 7. ing.

Reference numeral 10 denotes a plasticizing device moving member, which has one end mounted on the opposite side of the hydraulic cylinder 6 of the plasticizing device 4 and the other end mounted on the fixed frame 11 of the molding machine on the side opposite to the fixed platen 1 of the device 4. A pneumatic cylinder, the cylinder 10 is connected to a pneumatic source 14 via a switching valve 12 and a pressure reducing valve 13. 15 is a pressure gauge.

16, the fixed platen 1 is fixed by a mold clamping device 17;
The platen 16 is a movable platen that can move forward and backward relative to the platen 16, and a movable mold 18 is attached to the platen 16.

19 is an intermediate mold disposed between the fixed mold 3 and the movable mold 18, and the mold 19 is connected to the mold clamping device 1.
7, it is configured to be movable between the mold 18 and the fixed mold 3 in conjunction with the movement of the movable mold 18 via a rack and pinion mechanism described later. This intermediate mold 19 is provided with a long nozzle 20 that penetrates the fixed mold 3 and projects toward the injection nozzle 5 side. The rack and pinion mechanism includes racks 21 and 22 attached to the fixed die 3 and the movable die 18 so as to face each other vertically, and a pinion 23 attached to the intermediate die 19 and meshed with the racks 21 and 22. It is composed of.

(Function) When the movable mold 18 is opened and closed by the mold clamping device 17, the intermediate mold 19 is moved by the rack and pinion mechanism 21.
23, the movable mold 18 moves by 1/2 of the amount of movement of the mold 18 in conjunction with the movement of the movable mold 18, so the molds 3 and 19 and 18 and 19 are opened and closed at the same time.

During the molding operation, the coil 12a of the switching valve 12 that controls the pneumatic cylinder 10 is constantly excited, and compressed air at a constant pressure controlled by the pressure reducing valve 13 is supplied to the extrusion side of the pneumatic cylinder 10 (the forward side of the plasticizing device). is supplied. Therefore, the plasticizing device 4 is constantly pressed against the mold side by the pneumatic cylinder 10, so the injection nozzle 5 opens and closes the mold while closely contacting the long nozzle 20 of the intermediate mold 19 with a constant relatively small force. The movement of the intermediate mold 19 is followed. On the other hand, the coils 7a and 7b of the switching valve 7 that controls the hydraulic cylinder 6 during the mold opening/closing process are demagnetized and held at the neutral position shown, but during the injection holding process (mold clamping), the switching valve 7 is The coil 7b is excited and pressure oil is supplied to the retraction side (plasticizing device forward side) of the hydraulic cylinder 6, so that the injection nozzle 5 and the intermediate mold 19
The long nozzle 20 is pressed with a large force corresponding to the injection pressure.

After the mold clamping process is completed, in order to release the pressure bond between the injection nozzle 5 and the long nozzle 20 before proceeding to the mold opening/closing process, the coil 7b of the switching valve 7 is demagnetized and returned to the neutral position shown. , the hydraulic cylinder 6 becomes free. On the other hand, the coil 12a of the switching valve 12
continues to be energized, and the plasticizing device 4 is pressed against the mold side by the pneumatic cylinder 10.

Therefore, even during the mold opening and closing process, the injection nozzle 5
The long nozzle 20 is in close contact with the rack and pinion mechanisms 21 to 23 that open and close the intermediate mold 19.
Therefore, it is preferable that the adhesion force exerted by the pneumatic cylinder 10 is small. For this reason, the pressing force by the pneumatic cylinder 10 is not only controlled to the minimum force necessary to keep the mold and nozzle in close contact, but also the piston seal of the hydraulic cylinder 6 is made of low-sliding material such as Teflon. The hydraulic circuits 7 to 9 are constructed with resistance, and the hydraulic circuits 7 to 9 are also constructed with low pressure loss, and the bearings for moving the plasticizing device are constructed with low sliding resistance such as ball bearings to reduce mold opening and closing force. The increase is being prevented.

Note that the pneumatic circuit for supplying compressed air at a constant pressure to the pneumatic cylinder 10 includes a pressure reducing circuit 12.
-15, but may be a constant pressure supply circuit using a sequence valve, a variable displacement pump using an accumulator, or the like.

Furthermore, in this embodiment, a case is illustrated in which the hydraulic cylinder 6 is arranged between the fixed platen 1 and the plasticizing device 4, and the pneumatic cylinder 10 is arranged between the fixed frame 11 and the plasticizing device 4. , the same effect can be obtained even if these are replaced.

(Effects of the invention) As described above, the present invention moves the plasticizing device to follow the movement of the intermediate mold as the mold is opened and closed during molding operations, and keeps the injection nozzle and the intermediate mold (long nozzle) in close contact with each other at all times. Therefore, there is no possibility of air intrusion into the molded product, color unevenness, unevenness, etc. of the molded product, and the quality of the molded product can be reliably improved. The hydraulic cylinder is dedicated to the high-pressure nozzle touch, and the pneumatic cylinder moves the plasticizing device, which simplifies the control of hydraulic and pneumatic pressures and requires only a simple hydraulic and pneumatic circuit, reducing production costs. be able to.

[Brief explanation of the drawing]

The drawing is a schematic diagram showing an embodiment of the present invention. 1... Fixed platen, 2... Molding machine frame,
3...Fixed mold, 4...Plasticizing device, 5...Injection nozzle, 6...Hydraulic cylinder, 7...Switching valve, 8
... Hydraulic source, 10 ... Pneumatic cylinder, 11 ... Fixed frame, 12 ... Switching valve, 13 ... Pressure reducing valve,
14...Air pressure source, 16...Movable platen, 17...
...Mold clamping device, 18...Movable mold, 19...Intermediate mold, 20...Long nozzle, 21, 22...Rack, 23...Pinion.

Claims (1)

[Scope of utility model registration request] One end is attached to a fixed platen or fixed frame, the other end is attached to a plasticizing device, and a hydraulic cylinder for high pressure nozzle touch is connected to a hydraulic power source via a switching valve, and one end is attached to a fixed frame or fixed platen. The other end is attached to the plasticizing device, and a pneumatic cylinder for moving the plasticizing device is connected to a pneumatic source via a switching valve, and the injection nozzle and mold are constantly connected during the molding process. A nozzle touch and nozzle moving device for an injection molding machine, characterized in that the nozzle touch and nozzle moving device are kept in close contact with each other by constant pneumatic pressure, and are crimped by hydraulic pressure during injection and pressure holding processes.