JPH0132053B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an injection molding machine, and more particularly to a screw in-line type injection molding machine in which a screw kneads and melts a thermoplastic resin material and supplies it to a mold.

[Technical background of the invention and its problems]

As schematically shown in Fig. 3, a screw in-line injection molding machine uses a screw to transport a thermoplastic resin material while heating and melting it and supplying it to a mold.
A screw 2 is inserted into the heating cylinder 1, a hopper 4 is attached to a bracket 3 fitted to the base of the cylinder 1, and a thermoplastic resin material 5 is opened from the hopper 4 into the bracket 3 at the lower end of the hopper 4. The resin material is supplied through the resin material supply hole 6 to the cut-up portion 2a at the base of the screw 2, and while the screw 2 rotates to convey the resin material 5 toward the tip of the screw 2, it is kneaded and melted and then supplied to the mold. .

In the case of an injection molding machine having such a configuration, two types of feeding of the resin material 5 are performed during one molding cycle. That is, during the injection stroke, a starvation supply due to natural falling from the hopper 4 as the screw 2 moves forward, and a high-density supply due to forced winding into the screw 2 by the next rotation of the screw 2 are repeated.

As a result, sparse and dense states alternately exist within the cylinder 1, as shown in FIG.
This extends not only to the feed zone F of the screw 2, but also to the compression zone C and metering zone M, and even after the resin material 5 is melted, the dense and dense states of the melt resin alternate as shown in FIG. will exist in

Therefore, the amount of melt resin supplied from the tip measured by the metering zone M of the screw 2 fluctuates, resulting in unstable molding, abnormal internal pressure inside the cylinder 1, and even galling and abnormal wear. This is the cause of the problem.

[Purpose of the invention]

In view of this, the present invention was made with the aim of eliminating the drawbacks of the above-mentioned prior art, and it eliminates variations in the amount of resin material supplied into the cylinder,
An object of the present invention is to provide an injection molding machine that prevents uneven supply of melt resin.

[Summary of the invention]

In order to achieve the above object, the present invention provides a guide groove in the cylinder that communicates with the resin material supply hole and extends in the direction of the cut-up portion of the base of the screw, and stores the resin material in the cylinder in preparation for the next injection operation of the screw. The reason is that it has a structure that allows it to be used.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to the embodiment shown in FIGS. 1 and 2, using the same reference numerals for parts common to those in FIGS. 3 to 6.

FIG. 1 shows a cross section of a main part of an embodiment of the present invention, and FIG. 2 shows a cross section with the screw retracted and the resin material 5 being supplied.

In the illustrated embodiment, a hopper 4 is supported by a bracket 3 fitted on the outer periphery of the base of the cylinder 1, and a resin material supply hole 6, which is bored in the bracket 3 and communicates with the lower end of the hopper 4, is bored in the cylinder 1. It communicates with a guide groove 7 provided therein. The front end 7a of the guide groove 7 is aligned with the front end of the supply hole 6, and the rear end 7b extends to approximately the same position as the cut-up portion 2a when the screw 2 is retracted.

Therefore, the resin material 5 in the hopper 4 falls freely and enters the guide groove 7 from the supply hole 6 when the screw 2 retreats, and as the screw 2 moves forward, the resin material 5 in the hopper 4 falls into the cut-up portion 2a at the base of the screw 2 as shown in FIG. filled with. After that, when the screw 2 moves forward, the resin material 5 contained in the raised base portion 2a side of the screw 2 is sent out, so the resin material 5 is no longer densely packed, and the same resin material supply density as during measurement can be maintained. can.

〔Effect of the invention〕

As explained above, the present invention utilizes a screw in-line method in which a screw is inserted into a heating cylinder, and the thermoplastic resin material supplied into the cylinder is kneaded and melted while being fed by the screw, and then supplied to a mold. In the injection molding machine, the cylinder is provided with a guide groove that communicates with the resin material supply hole opened in the cylinder and extends in the direction of the cut-up portion of the base of the screw, so that the resin material is stored in the cylinder in preparation for the next injection operation of the screw. As a result, the resin material is not densely distributed over the entire area of the screw, the resin is uniformly supplied, and the quality of the molded product can be stabilized. In addition, the weighing plasticization time is shortened,
This has various effects such as stabilizing the repeated measurement density.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of the main parts showing one embodiment of the present invention, Fig. 2 is a cross-sectional view showing the state when the same resin material is being supplied, and Fig. 3 is an overview of a screw-in-line injection molding machine. The sectional views and FIGS. 4 to 6 are explanatory diagrams showing the state of densification of resin according to the prior art. 1... Heating cylinder, 2... Screw, 2a...
...Round up part, 3...Bracket, 4...Hoppa,
5...Resin material, 6...Resin material supply hole, 7...
Guiding groove.

Claims (1)

[Claims] 1. In a screw in-line injection molding machine, a screw is inserted into a heating cylinder, and the thermoplastic resin material supplied into the cylinder is kneaded and melted while being fed by the screw, and then supplied to the mold.
The cylinder is provided with a guide groove that communicates with the resin material supply hole opened in the cylinder and extends in the direction of the cut-up portion of the base of the screw, so that the resin material is stored in the cylinder in preparation for the next injection operation of the screw. injection molding machine.