JP2524293B2 - Molding machine for hollow molded products - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding machine used for molding a hollow molded article by injecting a fluid into a cavity of a mold in which molten resin is injected.

[0002]

2. Description of the Related Art As a molding machine of this type, Japanese Patent Publication No. 57-1
The one described in Japanese Patent No. 4968 is well known. In this molding machine, a fluid injection port is provided in the tip of the injection cylinder.

[0003]

The problem with the prior art is that the structure inside the tip of the injection cylinder is more complicated than that of a normal injection cylinder, so that it is troublesome to change the material or the color. Since the cost will be high and the flow resistance will increase due to the members that make up the fluid inlet,
For the molding, an injection device with a large injection pressure is required, and these tend to increase the cost.

The present invention has been conceived in order to solve the above-mentioned conventional problems, and its purpose is to construct a fluid injection means separately from an injection cylinder, and to inject this fluid injection means with a molten resin. It is an object of the present invention to provide a new molding machine which can be used for molding a hollow molded product even by an injection device having a normal configuration by operating later.

[0005]

The features of the present invention according to the above-mentioned objects are that a mold clamping device is provided with a split mold on the opposite side of a fixed platen and a movable platen, and a movable mold is located outside the fixed platen. And an injection device in which the nozzle at the tip of the injection cylinder touches the die on the stationary platen side, and an injection head at the tip is positioned so that it can come into contact with and separate from the nozzle touch portion of the die, and the injection head is attached to the side portion of the injection cylinder. It is composed of a fluid injection device arranged.

[0006]

[Operation] After the mold clamping is completed, the injection device moves forward, the nozzle of the injection cylinder touches the nozzle touch part of the mold on the fixed platen side, and a predetermined amount of molten resin is injected into the mold cavity. The injection device moves backward or moves to the side and stands by.

When the fluid injecting device is operated, the injecting head comes into contact with the nozzle touch portion of the mold, thereby maintaining the pressure, and at the same time, the fluid such as inert gas, liquid nitrogen, and hot water is discharged from the fluid supply source through the fluid pipe. Pumped to the injection head,
The fluid is then pressed into the cavity.

Since the molten resin in the cavity forms a hollow body by gas pressure, the injection head is separated from the nozzle touch portion of the mold and returned to its original position after pressure-holding cooling. The injection device is returned again, the nozzle is touched, and the molten resin is injected into the passage formed by the injection of the fluid to perform packing.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS This embodiment is a case where the fluid injection device is composed of an air or hydraulically actuated cylinder.
Is a mold clamping device, 2 is an injection device, and 3 is a fluid injection device.
The mold clamping device has a fixed platen 12 having an insertion port 11 at the center.
And a movable platen 14 in which a mold clamping ram 13 is connected to the center of the back part, and split molds 15 and 16 are attached to the opposite sides of both plates.

Reference numeral 2 denotes an injection device, which has a normal structure in which an injection screw 23 is provided inside an injection cylinder 22 having a nozzle 21 at its tip.

Reference numeral 3 denotes a fluid injection device disposed on the side of the injection cylinder 22, which is constructed by combining two sets of cylinders operated by air or hydraulic pressure. One of the cylinders has the injection cylinder 22 as the injection cylinder 31.
A fluid injection head 33 is attached to the tip of the piston 32 and is arranged in parallel on the side of the.

The other cylinder is arranged as a moving cylinder 34 which also functions as a support for the injection cylinder 31, at a right angle, and a piston 35 is connected to the side portion of the injection cylinder 31.

The fluid injection head 33 is hollow and has a tip formed into a nozzle, and a fluid pipe 36 from an accumulator (not shown) serving as a fluid supply source is connected to the rear portion.

In the molding machine having such a structure, as shown in FIG.
As shown in FIG. 6, when the mold clamping of the split molds 15 and 16 is completed by the forward movement of the movable platen 14, the injection device 2 moves forward to nozzle-touch the nozzle 21 of the injection cylinder 22 to the mold sprue bush. Then, as shown in FIG. 2, a predetermined amount of molten resin 24 is injected into the cavity 17 of the mold.

After the injection, the injection device 2 moves backward and stands by. When the backward movement is completed, the moving cylinder 34
The forward movement of the piston 35 extends the piston 35 to move the injection cylinder 31 to the position where the injection cylinder 22 has reached. Then, it stops on the axis of the injection cylinder 22. Immediately before or after the stop, the injection cylinder 31 operates and the piston 32 extends. As a result, the injection head 33 moves forward, and the nozzle at the tip touches the mold sprue bush through the insertion port 11 of the stationary platen 12, as shown in FIG. As a result, the pressure of the molten resin previously injected is maintained.

Further, the injection head 33 is pressure-fed with fluid from the accumulator through the gas pipe 36 by opening the valve, and the fluid is ejected from the nozzle to the cavity 1.
7 is pressed into the molten resin. Since the molten resin 24 in the cavity 17 forms a hollow body by the gas pressure, the piston 32 is contracted after the pressure holding cooling to separate the injection head 33 from the mold sprue, and the piston 3 of the moving cylinder 34 is further moved.
5 is returned and the injection cylinder 31 is returned to the original position.

After that, the injection device 2 is again moved forward so that the nozzle is touched, and as shown in FIGS. 4 and 5, the molten resin is injected into the passage 41 formed by the injection of the fluid to perform the packing 25.

FIGS. 6 and 7 show an example of arrangement of the injection device 2 and the fluid injection device 3 with respect to the mold clamping device 1. FIG.
A fluid injecting device 3 is obliquely movable forward and backward at the front of the injection device 2 installed on the machine base 5 together with the mold clamping device 1 so that injection of molten resin and injection of fluid can be performed alternately. It will be.

Further, FIG. 7 shows a guide rail 6 on the machine base 5.
6 is installed so that the base plate 7 can be moved horizontally in the horizontal direction, the injection molding machine 2 and the fluid injection device 3 are installed side by side on the base plate 7, and the base plate 7 is laterally moved by the hydraulic cylinder 8 or the like. By the movement, the injection molding machine 2 and the fluid injection device 3 are alternately touched with the nozzle so that the injection of the molten resin and the injection of the fluid can be performed.

[0020]

EFFECTS OF THE INVENTION The present invention has the following effects because it comprises a molding machine for hollow molded articles as described above. Since the fluid injection port is configured as a fluid injection head and is configured separately from the injection cylinder, the injection device may have a normal configuration, and it is not necessary to use a special-purpose machine having a special configuration for a hollow molded product.

Since there is nothing in the tip portion of the injection cylinder that causes flow resistance of the molten resin, a large ejection force is not required, and the material and the color can be easily changed. The molding cost can be reduced because it is possible to mold the hollow molded product using a molding machine having an ejection force suitable for the projected area.

Since the molding can be performed only by alternately performing the nozzle touch of the injection device and the nozzle touch of the fluid injection device, there is no technical difficulty in the operation, and the use of the cylinder operated by air or hydraulic pressure As a result of always ensuring the positioning of the fluid injection device and the nozzle touch, there is little molding loss.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a molding machine for hollow molded products according to the present invention.

FIG. 2 is a schematic sectional view of the same when a molten resin is injected.

FIG. 3 is a schematic cross-sectional view of the same when a fluid is injected.

FIG. 4 is a schematic cross-sectional view of the same when a hollow molded product is molded.

5 is a partially enlarged view of FIG.

FIG. 6 is a partial plan view of the molding machine showing an arrangement state of an injection device and a fluid injection device with respect to the mold clamping device.

FIG. 7 is a partial plan view of the molding machine showing another arrangement state of the injection device and the fluid injection device with respect to the mold clamping device.

[Explanation of symbols] 1 mold clamping device 2 injection device 3 fluid injection device 4 hollow molded product 5 machine stand 7 base plate 11 insertion port 12 fixed plate 13 mold clamping ram 14 movable plate 15 split mold 16 split mold 17 cavity 21 Nozzle 22 Injection cylinder 23 Injection screw 24 Molten resin 25 Packing 31 Injection cylinder 32 Piston 33 Injection head 34 Movement cylinder 35 Piston 36 Fluid pipe 41 Passage

Claims (1)

(57) [Claims] 1. A mold clamping device in which a split mold is mounted on the side opposite to a fixed platen and a movable platen, and a nozzle at the tip of an injection cylinder positioned so as to move forward and backward outside the fixed platen is on the fixed platen side. It is characterized by comprising an injection device for touching the die with a nozzle, and a fluid injection device arranged on the side of the injection cylinder with an injection head at the tip being positioned so as to be freely separable from the nozzle touch part of the die. Molding machine for hollow molded products.