JPS6313810B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nozzle device for an injection molding machine used for injection molding of crosslinkable polymer materials such as thermoplastic resins or rubber.

FIG. 1 shows an example of a conventional plasticizing injection device.
This conventional injection device melts and injects resin by the following actions. The material input from the hopper 1 is transferred to the left in FIG. Then, it is gradually melted by internal heat generated by the rotation of the screw 3. As the molten material is accumulated at the tip of the cylinder 4, the screw 3 is pushed back to the right in FIG. 1, and a predetermined amount of molten material is accumulated at the tip of the cylinder 4. When a predetermined amount of molten material is accumulated, hydraulic oil is sent to the injection cylinder 5, thereby moving the screw 3 to the tip side of the cylinder 4. Therefore, the molten material at the tip of the cylinder 4 is injected into a mold (not shown) through the nozzle 6, and a molded product having a predetermined shape is obtained.

However, with the above-mentioned injection device, when molding materials mixed with pigments such as dry colors and master batches, if the kneading action of the screw is not sufficient, the pigments will not be dispersed properly, resulting in molding defects. This may occur. To solve this problem, a nozzle device with a mixing function is used. Conventional nozzle devices are shown in FIGS. 2 to 4, respectively. The nozzle arrangement shown in FIG. 2 is of the type with a torpedo 7, the nozzle arrangement shown in FIG. 3 is of the type with color dispersion plugs 8 and 8', and the nozzle arrangement shown in FIG. This type has a static mixer 9. All of the above types of nozzle devices improve mixing and dispersion performance by passing the molten material accumulated at the tip of the screw or plunger through a narrow gap during injection.

However, with such conventional nozzle devices, only constant kneading and dispersion performance can be obtained.
When it became necessary to change the kneading and dispersion performance, it was necessary to change the equipment. That is, it was necessary to change the shape, dimensions, etc. of the torpedo, color dispersion plug, and static mixer. For this reason, there were problems in that a long working time was required to replace the parts, resulting in poor efficiency, and the need to prepare parts of various shapes increased the cost of the device.

The present invention has been made by focusing on the above-mentioned problems in the nozzle devices of conventional injection molding machines. By making it possible to easily adjust the gap in the flow path by moving the cylinder head in the axial direction,
The purpose is to solve the above problems.

Hereinafter, the present invention will be explained based on FIG. 5 of the accompanying drawings showing an embodiment thereof.

First, the configuration will be explained.

At the tip of the cylinder 12 containing the screw 11, there is a male threaded portion 13 and a cylindrical portion 1 in order toward the tip.
4 and a conical convex portion 15 are formed. A passage hole 16 communicating with the inner diameter portion of the cylinder 12 communicates with the surface of the conical convex portion 15 through a passage hole 17 . A cylinder head 19 having a conical concave portion 18 corresponding to the conical convex portion 15 is attached to the tip of the cylinder 12 . The cylinder head 19 is aligned by fitting the hole 20 continuous from the large diameter part of the conical recess 18 into the cylindrical part 14 of the cylinder 12, and screwing the female threaded part 21 into the male threaded part 13 of the cylinder 12. It is fixed to the cylinder 12 by. Note that a lock nut 22 is provided to prevent loosening between the male threaded portion 13 and the female threaded portion 21. A material flow path 23 is formed between the conical convex portion 15 of the cylinder 12 and the conical concave portion 18 of the cylinder head 19. Cylinder head 19
A passage hole 2 communicating with the material flow path 23 is provided at the tip of the
A nozzle 25 with 4 is attached by screws on its outer periphery. Heaters 26 and 27 are provided on the outer periphery of the cylinder 12, and a heater 28 is provided on the outer periphery of the cylinder head 19.

Next, the effect will be explained.

The plasticized and melted material accumulated by the screw 11 is pushed out through the passage hole 16, the passage hole 17, the material flow path 23, and the passage hole 24 while being kept warm by the heaters 26, 27, and 28. , is filled into a mold (not shown). The molten material is subjected to a large shearing action as it passes through the narrow material flow path 23, and the pigment contained in the material is sufficiently dispersed. Therefore, stable and high quality molded products can be obtained. When the molding material or the pigment used is changed, the gap δ of the material flow path 23 can be easily reset to the most appropriate value accordingly. That is, if the lock nut 22 is loosened and the cylinder head 19 is rotated, the cylinder head 19 will move in the axial direction, so the lock nut 22 can be tightened when the gap δ in the material flow path 23 reaches a desired value. Therefore, the gap δ of the material flow path 23 can be easily adjusted without disassembling the device.

Note that when the gap δ in the material flow path 23 is made smaller, the pressure loss when the material passes increases, and since this pressure loss becomes thermal energy, the material temperature rises rapidly. For this reason, the ability to fill the mold with the amount of material in the case of a thin-walled molded product is improved. Furthermore, if the mold is filled at the same material temperature, the temperature of the molten material accumulated in the cylinder can be lowered, and discoloration, burning, etc. due to material retention can be prevented.

The above explanation was for the case where a thermoplastic resin was used as the temperature, but the nozzle device of the injection molding machine according to the present invention can also be used when molding materials that involve a thermal crosslinking reaction such as rubber. You can get a big effect. When injection molding rubber, in order to prevent the thermal crosslinking reaction from proceeding inside the cylinder, the material is usually accumulated at a temperature of 100℃ or less, and then heated to about 180℃. The material is injected and filled into a mold to undergo a thermal crosslinking reaction. In this case, since the molded article is gradually heated by heat transfer from the mold to the material, a considerably long time is required until the thermal crosslinking reaction is completely completed. For this reason, molding of rubber requires a longer time than molding of normal thermoplastic resin. However, when injection molding of rubber material is performed using the nozzle device of the injection molding machine according to the present invention, the material passes through a narrow material flow path just before being filled into the mold, and at that time, the temperature of the material increases significantly. Rise. Therefore, the thermal crosslinking reaction is completed within a short time. According to test results in which rubber material was injected using the nozzle device of an injection molding machine according to the present invention, it was found that the rubber material, which was maintained at a temperature of approximately 100°C in the cylinder, had a temperature of 150 to 160°C immediately before entering the mold.
The temperature had risen to ℃. As a result, the thermal crosslinking reaction could be completed within 1/2 to 1/3 of the time compared to conventional equipment. This greatly improves productivity. In addition, the fluidity, hardness, etc. of rubber materials generally vary significantly depending on the material composition, so
It is necessary to adjust the size of the aperture during injection depending on the material, but using the nozzle device of the injection molding machine according to the present invention, the gap δ in the material flow path 23 can be easily adjusted.
can be adjusted, so the rubber material can be molded under optimal molding conditions.

As explained above, according to the present invention, a material flow path is formed between the conical convex portion formed at the cylinder tip and the conical concave portion formed in the cylinder head assembled to the cylinder tip, and the cylinder Since the head can be fixed at a desired axial position relative to the cylinder, the cross-sectional area of the material flow path can be easily adjusted, providing optimal kneading and dispersion performance according to the properties of the material. You can get the effect that you can.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a conventional plasticizing injection device;
3 is a sectional view of a conventional nozzle device, FIG. 4 is a sectional view of a conventional nozzle device, and FIG. 5 is a sectional view of a nozzle device that is an embodiment of the present invention. It is a diagram. 11... Screw, 12... Cylinder, 13...
...Male thread part, 14... Cylindrical part, 15... Conical convex part, 16... Passage hole, 17... Passage hole, 18...
...Conical recess, 19...Cylinder head, 20
... Hole, 21 ... Female thread part, 22 ... Lock nut, 23 ... Material flow path, 24 ... Passage hole, 25 ...
... Nozzle, 26, 27, 28... Heater.

Claims (1)

[Claims] 1 A material flow path is formed between a conical convex portion formed at the cylinder tip and a conical recess formed in the cylinder head assembled to the cylinder tip, and the cylinder head is aligned with the desired axis relative to the cylinder. Injection molding machine nozzle device that can be fixed in directional position.