JP3048664B2 - Injection molding method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for plastic injection molding, and more particularly to a method for cutting a gate in an ideal state in a mold during injection molding so that a product part and a runner can be taken out in a separated state. Injection molding method and apparatus.

[0002]

2. Description of the Related Art Conventionally, in injection molding, a gate of a molded article is cut in a softened state by generating internal heat in plastic near a gate cutting position by vibration energy as shown in, for example, Japanese Patent Application Laid-Open No. 1-264821. A method of moving the gate cutting member to perform high-speed cutting is disclosed. In this case, the hydraulic cylinder is controlled by a closed loop servo using a servo valve.

[0003]

Conventionally, when vibration is generated to generate internal heat in the plastic near the gate cutting position and the gate cutting member is moved in a softened state to perform high-speed cutting, a hydraulic cylinder uses a servo valve. Servo control, so the servo valve,
Not only expensive equipment such as filters, function generators, servo amplifiers, operating transformers, amplifiers, etc. are required, but hydraulic equipment also requires advanced maintenance such as oil contamination management, including servo valves and filters.
And advanced electrical control technology was required. An object of the present invention is to generate internal heat in plastic near a gate cutting position by vibration energy, and to move a gate cutting member in a softened state to perform high-speed cutting, using a hydraulic cylinder using a servo valve. Instead of closed-loop servo control, open-loop control using an inexpensive solenoid valve allows the gate to be cut in an ideal state in the mold during injection molding, and the product part and runner can be taken out separately. An object of the present invention is to provide an injection molding method and apparatus.

[0004]

Accordingly, the present invention has solved the above-mentioned problems of the prior art by providing an injection molding method and apparatus described in the claims.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described. FIG. 1 shows a main part of an injection molding apparatus having a four-movable movable mold 6, a cylinder and a hydraulic circuit diagram of the present invention. FIG. 5 is a sectional view showing a movable mold 6 used in the injection molding method of the present invention.
The portion shows a cross section taken along line AB in FIG. FIG. 2 is a cross-sectional view taken along line BB of FIG. 1, and FIG. 3 is a chart showing the switching position of each solenoid valve of FIG. 1 during operation.

The mold includes a fixed mold 25 and a movable mold 6, and a cavity or a core 4 for molding a product portion is formed on a contact surface between the two molds 25 and 6. In the movable mold 6,
A slider member 5 that forms a part of the runner portion 2 and has an edge 26 that can be gate-cut is detachably disposed in the movable mold 6 and is connected to the vibration cylinder rod 8 of the first cylinder 7. Thereby, it is slidably mounted left and right as seen in FIG. Reference numeral 3 denotes a sprue formed in the fixed mold 25. In the embodiment, one part of the runner part 2 is provided on the movable mold 6 side, and the runner part 2 and the gate part 1 are provided on the slider member 5 on the contact surface with the fixed mold 25.
It is provided in the shape of a groove. The runner 2 connects the gate 1 and the sprue 3. The runner section 2 of the slider member 5 is in communication with the runner section 2 on the movable mold 6 side. 20 is a product discharge pin, 21 is a sprue discharge pin,
Reference numeral 22 denotes a gate discharge pin. Each pin is fixed to the ejector plate 24 and penetrates through the fixed mold 25. After the movable mold 6 is opened by a device (not shown), the ejector plate 24 is removed. The product, sprue, and gate are discharged by moving to the right as viewed in FIG. The fixed mold 25 is fixedly supported by an injection molding apparatus main body (not shown).

The vibration cylinder rod 8 and the first cylinder 7 main body connected to the slider member 5 are connected to the cylinder main body 28 of the second cylinder 9 by the connection member 14, and the cutting cylinder rod 10 of the second cylinder 9 is connected to the cutting cylinder rod. A mounting ring 27 with an ejector cylinder rod 12 integral with 10; And is attached to the movable mold 6 via. Reference numeral 40 denotes an air vent when the end of the cutting cylinder rod 10 enters and exits the space 41. The vibration cylinder rod 8 has a small-diameter vibration piston 29, and the cutting cylinder rod 10 has a medium-diameter cutting piston 3 having a larger diameter than the small-diameter piston.
0, and a large-diameter ejector piston 31 having a larger diameter than the medium-diameter piston is fixed to the ejector cylinder rod 12, the second cylinder exerts a larger force than the first cylinder, and the third cylinder exerts a force greater than the second cylinder. It is designed to exert more power. Alternatively, use a different cylinder diameter from the above and supply a different hydraulic pressure to each cylinder,
Similarly, the second cylinder may exert a greater force than the first cylinder and the third cylinder may exert a greater force than the second cylinder. Each oil chamber 3 provided on both sides of each piston
2, 33, 34, 35, 36, and 37, pressure oil is guided from a hydraulic pressure source 38 via solenoid valves 17, 17, 18, and 19. Reference numerals 7, 9, and 11 denote a cylinder body, 15 denotes a cover flange, 16 denotes a spacer, and 13 denotes an amplitude adjusting spacer for adjusting the stroke of the small-diameter vibrating piston 29.

Pressure oil is introduced into the oil chambers 32, 33 provided on both sides of the small-diameter piston 29 from the hydraulic pressure source 38 via the high-speed switching ON-OFF solenoid valves 17, 17, and is turned on at high speed. By switching the -OFF solenoid valve, the small-diameter vibrating piston 29, the vibrating cylinder rod 8, and the slider member 5 can be minutely reciprocated. By switching the solenoid valves 18 and 19 respectively, the slider member 4 is moved via the medium-diameter cutting piston 30 and the cutting cylinder rod 10 or the large-diameter ejector piston 31 and the ejector cylinder rod 12 to cut the gate. Or the U-cut portion 2 of the slider member 5
3 is moved to the gate 1. FIG. 3 shows the switching positions at the time of operation of each solenoid valve.

Next, the injection molding method of the present invention will be described. Inflow molten resin is introduced into a cavity or core 4 from a nozzle (not shown) of an injection molding machine through a sprue 3, a runner section 2 and a gate section 1. Or core 4
The product part inside is molded. The slider member 5 is held at the position shown in the drawing by the vibrating cylinder rod 8 of the first cylinder 7 at the time of injection when the cavity or the core 4 is filled with resin by injection molding and at the time of pressure holding. When the filling is completed, the cooling process is started while maintaining the pressure (the plastic shrinks as it is cooled, so that the filling is maintained to compensate for the shrinkage), and the gate portion 1 is cooled and solidified to seal the gate. Generally, since the cross-sectional area of the gate portion 1 is smaller than that of any part of the cavity or the core 4, the cooling of the gate portion 1 is quicker than the cooling of the product portion. (Even during the pressure-holding process after injection filling or during the cooling after the pressure-holding is completed) Cutting the product gate has no effect on the product.

After the gate seal is completed, that is, during the pressure-holding process after injection filling and during the cooling after the pressure-holding is completed, high-speed switching is ON.
-OFF solenoid valves 17 and 17 are turned ON-O at high speed.
The FF is switched so that the small-diameter vibrating piston 29, the vibrating cylinder rod 8, and the slider member 5 are minutely reciprocated. The minute reciprocating vibration of the small-diameter vibrating piston 29 causes the slider member 5 to reciprocate minutely. By giving this minute reciprocating vibration, the contact surface between the product part in the core 4 and the slider member 5 is locally heated in the cavity near the gate part 1 by the vibration energy, and the resin at the interface is heated and softened.

When the resin at the interface of the gate portion 1 is softened, the solenoid 18 is turned on, so that the medium-diameter cutting piston 30 of the second cylinder 9 is reduced in diameter along with the second cylinder 9 main body 28 and the entire first cylinder 7. The slider member 5 is forcibly moved to the left as viewed in FIG. 1 while the oscillation piston 29 is slightly reciprocated, and the gate is cut at the edge 26 of the slider member 5. Further small-diameter vibration piston 29
The surface 39 of the slider member 5 is brought into contact with the cut product surface for a short time while oscillating a small reciprocating vibration to make the product surface more clear. The vibration of the slider member 5 may give a gentle reciprocating motion for a short time. The steps of softening, compressing, and cutting the resin of the slider member 5 are completed within only a few seconds, and can be performed simultaneously with the cooling of the product part, which does not hinder productivity as compared with conventional molding.

In the case where the ejection can be performed in this state, after the gate is cut and the cooling is completed, the movable mold 3 is retracted in the same manner as in normal injection molding, the movable mold 6 is opened by a device (not shown), and the cavity or the core 4 is removed. The corresponding product section and runner section 2 are taken out and the molding process is completed. However, as shown in FIG. 2, when the product portion corresponding to 4 and the surface 39 of the slider member 5 cannot be ejected due to interference, the large-diameter ejector piston 31 and the ejector cylinder rod 12 are turned on by turning on the solenoid 19. 1, the slider member 5 is advanced to the left in FIG. 1 by moving the U-cut portion 23 of the slider member 5 to the gate portion 1 to eliminate the interference, open the movable mold 6, open a product portion corresponding to 4 and a runner portion. 2 is taken out and the molding step is completed. Before the next die clamping, the position of the slider member 5 is returned to the original position by each piston by turning off the solenoid valves 17, 17, 18, 19 so that the slider member 5 is prepared for the next molding.

[0013]

According to the present invention, high-speed switching ON-O
FF solenoid valve is switched ON-OFF at high speed,
The piston and slider member of the first cylinder are minutely reciprocated to generate internal heat in the plastic in the vicinity of the gate cutting position due to the vibration energy.
Gates can be cut by moving the piston and slider members of the cylinder. For this reason, instead of using a servo valve to perform closed-loop servo control of the cylinder,
Provided is an injection molding method and apparatus which can perform gate cutting in an ideal state in a mold during injection molding by open-loop control using an inexpensive solenoid valve and take out a product part and a runner in a separated state. With closed loop servo control using a conventional servo valve,
There is no need to use expensive equipment such as expensive servo valves, filters, function generators, servo amplifiers, operating transformers and amplifiers, and there is no need for advanced maintenance and advanced electrical control technology such as oil contamination management of hydraulic equipment. Needed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of an injection molding apparatus having a four-piece movable mold 6, a cylinder, and a hydraulic circuit diagram of the present invention;
The movable mold 6 used in the injection molding method of the present invention shows a cross section taken along line AB in FIG.

FIG. 2 is a sectional view of a main part taken along line BB of FIG. 1;

FIG. 3 is a chart showing a switching position at the time of operation of each solenoid valve of FIG. 1;

[Explanation of symbols]

 1, gate part 2, runner part 3, sprue 4 cavity or core 5, slider member 5, 6, movable mold 7, first cylinder 8, vibrating cylinder rod 9, second cylinder 10, cutting cylinder rod 12, ejector cylinder Rod 17, high-speed switching ON-OFF solenoid valve 18, 19 solenoid valve 25, fixed mold 27, mounting ring 29, small-diameter vibration piston 30, medium-diameter cutting piston 31 large-diameter ejector piston 32, 33, 34, 35, 36 , 37 Oil chamber 38 Hydraulic power source

Claims (4)

(57) [Claims] 1. A fixed mold and a movable mold for forming a cavity or a core for molding a runner section, a gate section and a product section on a contact surface, and a part of each of the runner section and the gate section in the movable mold. And a gate-cuttable slider member is slidably disposed, the slider member is reciprocated by a cylinder connected thereto, and the cylinder is a first cylinder connected to the slider member, And a second cylinder fixed to the movable mold having a larger output than the first cylinder so as to move the entire first cylinder. After the injection filling, after the gate seal is completed, the slider member is moved. The first cylinder fixed to the movable mold vibrates minutely in a reciprocating manner, and the minute reciprocating kinetic energy causes internal heat generation in the plastic near the gate cutting position. Causing, by moving the second cylinder in softened state, and while small reciprocally vibrate during which the first cylinder, wherein the slider member first
An injection molding method wherein the gate is forcibly moved together with the entire cylinder to cut the gate at a high speed. 2. After moving the second cylinder and cutting the gate at a high speed by using a third cylinder having a larger output than the second cylinder so as to move the entire second cylinder, the slider member is further moved. The injection molding method according to claim 1, wherein the injection molding is forcibly moved. 3. A fixed mold and a movable mold for forming a cavity or a core for molding a runner section, a gate section, and a product section on a contact surface, and a part of each of the runner section and the gate section in the movable mold. And a gate-cuttable slider member is slidably disposed, and reciprocated by a cylinder connected to the slider member. The cylinder includes a first cylinder connected to the slider member, and a first cylinder. A second cylinder fixed to the movable mold having a larger output than the first cylinder so as to move the entire cylinder;
The high-speed switching ON-OFF solenoid valve is communicated via an OFF solenoid valve at a high speed to ON-O.
FF switching is performed, and the first cylinder and the slider member are minutely reciprocated to generate internal heat in the plastic in the vicinity of the gate cutting position by vibrating energy. An injection molding apparatus characterized in that the gate can be cut by moving the nozzle. 4. The injection molding apparatus according to claim 3, further comprising a third cylinder having a larger output than the second cylinder so as to move the entire second cylinder.