JPS6246616A - Screw structure of screw injection machine - Google Patents

Abstract

PURPOSE:To prevent the strain after molding due to the admixture of unmolten resin, the color shading due to the ununiform dispersion of coloring material and the mixing of carbonized resin in a molded part and consequently obtain a good molded part by a structure wherein an auxiliary flight is provided in addition to the main flight of a screw at a compression zone as well as a melt zone. CONSTITUTION:The smaller the volume of a groove 10 lying between a main flight 8 and an auxiliary flight 9, which locates backward with respect to the direction of delivery of molten resin by proper interval, becomes, the nearer the groove 10 approaches the tip of a screw 2. On the contrary, the larger the volume of a groove 11 lying between the auxiliary flight 9 and the main flight 8, which locates backward with respect to the direction of delivery of molten resin by proper interval, becomes, the nearer the groove 11 approaches the tip of the screw. The height of the auxiliary flight 9 is made slightly lower than that of the main flight 8 and at the same time the clearance between the auxiliary flight 9 and a cylinder is made smaller than the particle diameter of synthetic resin material so as to allow only molten resin to pass through said clearance. Consequently, the effective kneading length increases and at the same time shearing energy is given to the resin by passing through the clearance 13 between the cylinder 12 and the auxiliary flight 9 so as to further increase the kneading effect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of the slurry 1 structure of a screw injection molding machine.

[Conventional technology]

In a typical screw injection molding machine, as shown in Fig. 2, synthetic resin material 1 is fed from a hopper 5 into a heating cylinder 4 having a heater 3 around its circumference by the rotation of a screw 2, during which it is heated and plasticized. is stored at the tip of screw 2. This pressure causes the screw 2 to retreat. When a predetermined amount of plasticized synthetic resin material 1 has accumulated at the tip of the screw 2, hydraulic pressure is sent to the hydraulic cylinder 6, and the screw 2 moves forward in the axial direction to inject the synthetic resin material into the mold 7.

[Problem that the invention seeks to solve]

In this type of screw injection molding machine described above, by increasing the effective kneading length, applying sufficient shearing energy to the resin when passing through the clearance, and increasing the resin filling pressure in the groove, Ideally, it would be possible to achieve a more uniform and efficient kneading effect, but with a single-flight type, it is impossible to achieve such an ideal kneading effect. Since the kneading effect cannot be obtained, the molten resin and unmelted resin are transported in a mixed state, and the heat from the heater acts unevenly, which is not only inefficient in terms of production efficiency, but also results in unmelted resin being mixed. This will adversely affect the molded product, such as distortion after molding and non-uniform dispersion of the coloring material.

The present invention adopts a double flight system, and in particular, in addition to the melt zone of the screw, a secondary fly 1- is provided in addition to the main flight within the screw pitch, and a secondary flight 1- is provided in addition to the main flight in the melt zone of the screw and the compression zone connected to this afterward. By returning the resin in the groove to the grooves of the sub-flight and main flight that are connected later, and repeating the forward feeding, the effective kneading length is lengthened, and sufficient shearing energy is applied to the resin when passing through the clearance, and the groove The kneading effect is further improved by increasing the resin filling pressure inside the chamber, so the molten resin and unmelted resin are transported separately, and the heater heat acts evenly on the resin, which makes it difficult for unmelted resin to mix, resulting in molding. It is an object of the present invention to provide a screw structure of a screw type injection molding machine that can produce molded products of high quality with less distortion afterward and evenly dispersed coloring material.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present invention provides a screw type injection molding machine in which when a predetermined amount of synthetic resin material is accumulated at the tip, the screw moves forward in the axial direction and injects the plastic into the mold. , a screw type injection characterized in that the compression zone of the screw and the melt zone connected thereto are provided with sub-flights at appropriate intervals in addition to the main flight within the l-screw pitch, and the screw groove is divided into two stages. The gist is the screw structure of the molding machine.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In Fig. 1, a main flight 8 and a sub-flight 9 are continuously formed within one screw pitch in the melt zone and compression zone of the screw 2, and the groove lO between the main flight 8 and the sub-flight 9 is generated by the reaction force of the resin feeding force. The groove 11 between the secondary flight 9 and the continuous main flight 8
Return to , and repeat forwarding again. That is, in the present invention, the volume of the groove 10 between the main flight 8 and the sub-flight 9 located rearward in the feeding direction with an appropriate interval decreases as it goes toward the tip of the screw 2, and 9 and the main flight 8 located rearward in the feeding direction at appropriate intervals, the groove 11 is formed so that its volume increases as it goes toward the tip of the screw, and the sub flight 9 is slightly higher in height than the main flight 8. Because the clearance between the secondary flight 9 and the cylinder is smaller than the particle size of the synthetic resin material, the resin sent to the groove 10 is compressed as it moves toward the tip of the screw 2, so the clearance is reduced by the reaction force. After passing through, it is temporarily stored in the groove 11. However, as described above, since the clearance is formed to be smaller than the resin particle diameter, solid unmelted resin cannot pass through, so only the molten resin passes through the clearance. As a result, the effective kneading length becomes longer, and the clearance between the cylinder 12 and the sub-flight 9 is 1.
During the third passage, shearing energy is applied to the resin, which further increases the kneading effect, and the filling pressure of the resin in the groove increases, which improves the kneading effect, and because the resin is fully supplied, charcoal resin is less likely to be mixed.

Furthermore, since the molten resin and unmelted resin are transported separately, the heat of the heater 3 acts uniformly on the resin, and the resin is melted uniformly, so that a suitable plasticized synthetic resin material is always injected into the mold 7. .

〔Effect of the invention〕

According to the present invention, in addition to the melt zone, the compression zone is also provided with the sub-fly 1- in addition to the main flight, thereby achieving a more favorable cross-contact condition as described above, and a uniform temperature effect of the heater heat on the resin. It is a suitable molded product because it is easy to obtain a uniform melted state of the resin, which prevents post-molding distortion due to the mixture of unmelted resin, uneven coloring due to non-uniform dispersion of coloring material, and contamination of charcoal resin. It became possible to obtain.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing a screw type injection molding machine, and FIG. 2 is a schematic sectional view showing the screw structure of the screw type injection molding machine of the present invention. 1...Synthetic resin material 2...Screw 3...Heater 4...Heating cylinder 5...Hopper 6...
Hydraulic cylinder 7...Mold 8...Main flight
9...Sub-flight 10.11...Groove 12...
Cylinder 13... Clearance patent applicant Jinsho Electric Industry Co., Ltd. Figure 1 Hand ^ Sacrilege ifj x! E Harm October 1985 7 [1 1985 Patent I'll No. 187032 2. Name of invention Screw structure of screw injection molding machine 3. +Ii
I will make a correction ((Relationship with the matter) Patent applicant address: 1-3-3 Koyama, Tokyo Parts Industry Ward Name: Ten 5
V Denki Kogyo Co., Ltd. (Representative) Kikuchi Okabe 4, Agent address 201 Kita 1 Shakukate Building 201, Shibuya 1, Shibuya-ku, Tokyo 1-□ Name (7132) Patent attorney Torobe Toshibe 11 5. In addition, according to the present invention, the extremely strong back pressure effect allows for color change or material replacement (residual resin is forcibly pumped out when replacing the material). The following statement has been added: ``It is easy to produce a molded product, and it also helps to efficiently obtain a suitable molded product.''

Claims (1)

[Claims] 1) In a screw-type injection molding machine in which a screw moves forward in the axial direction to inject plastic into a mold when a predetermined amount of plasticized synthetic resin material accumulates at the tip, the screw A screw type injection molding machine characterized in that the compression zone and the melt zone connected thereto are provided with sub-flights at appropriate intervals in addition to the main flight within one screw pitch, and the screw groove is divided into two stages. Screw structure. 2) The groove between the sub-flights, which is located rearward in the feeding direction at an appropriate distance from the main flight, decreases in volume as it goes toward the tip of the screw; 2. The screw structure of a screw type injection molding machine according to claim 1, wherein the groove between the main flights becomes larger toward the tip of the screw. 3) A screw structure of a screw type injection molding machine, characterized in that the flight height of the sub-flight is slightly lower than that of the main flight, and the clearance between the sub-flight and the cylinder is smaller than the particle size of the synthetic resin material.