JPH02178012A - Injection mold assembly - Google Patents

Abstract

PURPOSE:To make it possible to injection-mold molded items, which are colored different from each other in every cavity, by a structure wherein a kneading member equipped with a screw is rotatably and reciprocatably provided in the interior of each nozzle part and a colorant fed pipe is arranged so as to feed colorant to the kneading member. CONSTITUTION:Molten resin having natural color is filled from an injection tube 14 in a hot runner 15a. After that, by pressurizing each cylinder 23, each kneading member 21 is moved forward together with each piston rod 22 so as to fit the plunger tip of the kneading member 21 to each small diameter portion and to fit each spool part 20 to the rear end of each nozzle part in order to turn the interior of the nozzle part into one enclosed kneading chamber. After that, slight pressure is applied in opposite direction to each cylinder 23 so as to slightly retreat each piston 24 together with the kneading member 21. Since the pressure in the nozzle member 21 decreases as a result and the un-even density portion is developed, colorant by the amount for one shot is fed to the portion from each colorant feeding device 29. After that, by turning the kneading member 21 together with the piston 24 through the actuation of each motor 26, the molten resin and the colorant are kneaded together with each screw 19 so as to be turned into molten colored resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an injection mold device having a plurality of cavities within the mold.

[Prior art]

In injection molding, colored synthetic resin or non-colored resin and coloring agents are melted and kneaded in a hopper by a screw in an injection heating cylinder, and then injected into a mold to form colored synthetic resin products. . Therefore, the coloring of the molded product is determined by the coloring of the material resin injected into the mold, and when molding a molded product with a different color, the material resin or coloring agent in the hopper must be replaced, and then the injection molding is performed by emptying. Residual resin inside the heating cylinder is discharged and replaced with new resin material.

[Means for solving problems]

In order to completely change the material, several shots to 10 shots of actual molding are required after emptying, and the work requires several tens of minutes of time, human resources, resin, and energy.

Furthermore, in multi-cavity molds, the material resin that has accumulated in the hot runner block must also be replaced with new material resin, so there is a lot of waste when changing colors, which is uneconomical and especially difficult for high-mix, low-volume production. This also causes high costs for molded products.

This invention was devised to solve the above problems, and its purpose is to make it possible to perform only a small amount of emptying required for color change in a multi-cavity mold with uneven hot runner blocks. It is an object of the present invention to provide a new injection mold device capable of injecting material resins of different colors into gears and tees, and capable of injection molding molded products with different colors for each cavity.

(Means for Solving the Problems) The features of the present invention according to the above object include a mold having a plurality of cavities, a plurality of nozzle sections individually connected to the cavities, and a molten resin from an injection device to each nozzle. A kneading member equipped with a screw is provided inside the nozzle part so as to be rotatable and can move forward and backward, and a colorant supply pipe is arranged toward the kneading member. It's what I did.

(Function) In the above mold device, the uncolored molten material filled into the nozzle part from the hot runner and the coloring agent supplied into the nozzle part toward the kneading member are injected into the mold cavity. First, the kneading member is kneaded by rotating and moving back and forth,
The kneaded material is injected and filled into the cavity using new resin injection pressure. Further, uncolored molten resin is supplied into the nozzle portion from a hot runner.

〔Example〕

In the figure, 1 is a movable plate that moves forward and backward to open and close the mold by a mold clamping device (not shown).A movable mold 2 is attached to the mold mounting surface, and the opposing mold mounting surface of the fixed m3 is Fixed mold 4 is attached.

The contact surface (parting surface) of the movable mold 2 and the fixed mold 4 is provided with a recess 5.6 for inserting a nested mold, and the four parts 6 for inserting a molded mold of the fixed mold 1!14 are provided with molded parts. A pair of stationary insert molds 10, 10 are embedded in which a cavity 8 forming the outer shape of the mold 7 and a resin passage 9 communicating with the cavity 8 are carved. Further, a pair of movable nesting molds 13 and 13 having a core 11 forming the inner shape of the molded product 7 and a molded product ejection mechanism 12 are embedded in the nesting mold insertion recess 5 of the movable mold 2.

The fixed mold 4 is connected to the nozzle of an injection cylinder 14 provided on the back of the fixed plate, and branches the natural color molten resin injected from the injection cylinder 14 into the cavities 8 of each nested mold while maintaining the molten state. The hot runner block 15 to be supplied is inserted through a heat insulating material 16, and the hot runner block 15 has a nozzle portion 17.17 with a small diameter at the tip connected to the gate of each cavity 8.8 at right angles. It is connected to. Inside this nozzle part 17.17, a screw 19 having an outer diameter smaller than the inner diameter of the nozzle part is integrated around the plunger 18, and a kneading member 21 is provided with a sprue part 20 behind the screw 19. However, piston rod 2
The hot runner block 15 is connected to the tip of the hot runner block 15, and is fitted in the hot runner block 15 so that it can rotate and move forward and backward.

A piston 24 of a cylinder 23 provided in a fixed mold is attached to the shaft end of the piston end 22, and a gear 25 is provided on the side of the rod.

This gear 25 and the gear 27 of the motor 26 fixed to the side of the fixed mold mesh with and communicate with the idle gear 28, and the motor 26
The rotational force of [1 member 21] is transmitted to the piston rod 22.
Rotate.

A colorant supply pipe 30.3 of a colorant supply device 29.29 for supplying liquid colorant is attached to the side of each nozzle portion 17.17.
0, the discharge port is arranged in the direction Gt toward the kneading member side. Although not shown in the drawings, the colorant supply pipes f129 and 29 are provided with a backflow prevention means, and are stored with a colorant according to the purpose.

Kneading of materials in this mold device and injection filling into the gear tee are performed as follows.

With both of the kneading members 21 and 21 in the retracted position as shown in FIG. 2, natural color molten resin is filled into the hot runner 15a from the injection tube 14. Next, when the cylinder 23 is pressurized by hydraulic pressure or the like and the kneading member 21 is moved forward together with the piston rod 22, the plunger tip of the kneading member 21 fits into the narrow diameter portion as in the first fixed position, and the spool portion 20 is fitted to the rear end of the nozzle section, forming one kneading chamber with the inside of the nozzle section sealed.

After this state, change the pressure direction in the cylinder 23 and apply a slight pressure in the opposite direction to the above, and the piston 2
4, the kneading member 21 is slightly retracted to the extent that the fitting of the spool member 20 is not impaired. As a result, the pressure inside the nozzle member 21 is reduced and the nozzle member 21 becomes in a dense state, so that one shot of colorant is delivered therefrom from the colorant supply device 29.

After adding the colorant, when the motor 26 is operated to rotate the kneading member 21 together with the piston 24, the molten resin and the colorant are kneaded by the screw 19 to form a colored molten resin. At this time, since the screw diameter is slightly small, the material sent forward by the screw 19 is returned to the rear through the gap between the inner wall of the nozzle part and the outer end of the screw, and is wound around the screw 19 again and kneaded. Simultaneously with this kneading operation, when the kneading member 21 is reciprocated by a predetermined distance by cylinder operation, pressurization and depressurization are repeated in the nozzle portion 17, thereby further promoting kneading.

After coloring with sufficient kneading through the above operations,
When the kneading member 21 is moved backward to release the sealing by the spool section 20 and a new natural color molten resin is injected from the injection tube 14 to the hot runner 15a, the molten resin that was previously filled enters the nozzle section 21. The resin is press-fitted, and the colored resin in the nozzle portion is injected and filled into the cavity 8 by the pressure of the resin.

After filling with resin pressure, the kneading member 21 is advanced to close the nozzle tip with the plunger tip, pressure is maintained until a gate seal is generated, and then the kneading member 21 is sufficiently retreated by the cylinder 23 again, and then the next step is performed. Move on to the process.

If you want to change the color of the molded product 7.7, replace the colorant in the colorant supply device 29 and then perform several shots of molding to remove the colorant remaining in the nozzle and the colored resin. discharge. In this case, only a small amount of colored resin remains in the nozzle, and there is no retention m, so the color can be changed in a short time and with a small amount of resin.

Further, although the kneading members in the above embodiment are rotated by individual motors and gears, all the kneading members may be rotated by one motor. It is also possible to change the flight shape of the screw arbitrarily, such as to make it a two-thread type or a Lt mace type, and the number of cavities is not limited to two, but can be any number, and the molded product 7. 7 may be of the same shape or of different shapes, and it is more suitable to use a telescoping mold from the standpoint of responding to diversification; It may be.

〔Effect of the invention〕

As described above, the present invention provides a hot runner comprising a mold having a plurality of cavities, a plurality of nozzle sections individually connected to the cavities, and a hot runner that guides molten resin from an injection device to each nozzle section. - A kneading member equipped with a screw is provided inside the nozzle part so as to be able to rotate and move back and forth, and a colorant supply pipe is arranged toward the kneading member, and the melting member is provided inside the nozzle part of the mold. Since the resin can be colored, the molded product molded in one cycle can have a different color for each cavity. Further, since the colorant is kneaded by the rotation and forward and backward movement of the screw, the kneading time is shorter than when the colorant is passed through a kneading member, and the molding time does not become particularly long.

Similarly, color changes can be made in a short time, and there is little loss of resin materials or colorants due to color changes, making it ideal and easy to use for high-mix, low-volume production due to diversifying user needs.

[Brief explanation of the drawing]

The drawings show an embodiment of the injection mold of the present invention, and FIG. 1 is a schematic sectional view showing the left and right kneading members in different operating states, and FIG. 2 is a sectional view of the nozzle part. be. 1... Movable plate 2... Movable type 3... Fixed plate 4... Fixed type 7... Molded product
8...Capity 1o...Fixed nesting type
DESCRIPTION OF SYMBOLS 11... Core 13... Movable nesting mold 15... Hot runner block 15a... Hot runner 17... Nozzle part 18... Plunger 19... Screw 20...
... Sprue section 22 ... Rod rod 24 ... Piston 29 ... Colorant supply device 30 ... Colorant supply pipe 21 ... Kneading member 23 ... Cylinder 26 ... Motor

Claims (1)

[Claims] It consists of a mold having a plurality of cavities, a hot runner block equipped with a plurality of nozzle sections individually connected to the cavities, and a hot runner that guides the molten resin from the injection device to each nozzle section. A mold device for injection molding, characterized in that a kneading member equipped with a screw inside is provided so as to be rotatable and movable back and forth, and a colorant supply pipe is arranged toward the kneading member.