Injector

Abstract

The axial dimension of an injector (31) is decreased, inserting / removing work of a screw (20) is facilitated, and the qualities of a molding are enhanced. The injector has a heating cylinder (17), the screw (20), and a driver. The screw (20) has a main body portion (45a), and a plasticization portion provided with flights (53) formed to project from the outer circumferential surface of the main body portion (45a). Assuming the screw stroke is S, the effective length of screw is L, and a value obtained by dividing the sum of the screw stroke S and the effective length L of screw by the screw stroke S is an index e, the index e is set to satisfy a relation 2.0<Epsilon<4.5. Even if the screw (20) is shortened, resin can be melted well. Consequently, the axial dimension of the injector (31) is decreased.

Description

technical field [0001] The invention relates to an injection device. Background technique [0002] Conventionally, in a molding machine such as an injection molding machine, resin heated and melted in a heating cylinder is injected at high pressure and filled into a cavity space of a mold device, and cooled and solidified in the cavity space, thereby enabling Get moldings. [0003] Therefore, the injection molding machine includes a mold device, a mold clamping device, and an injection device. The mold clamping device includes a fixed platen and a movable platen, and the mold clamping cylinder closes the mold device by advancing and retreating the movable platen. Molding, mold closing and mold opening. [0004] On the other hand, the injection device generally uses a coaxial screw type injection device, and includes a heating cylinder for heating and melting the resin supplied from a hopper, and an injection nozzle for injecting the molten resin, and is rotatable in the he...

AI Technical Summary

Problems solved by technology

[0013] However, in the conventional injection device, such as figure 2 As shown, the resin supplied through the resin supply port 25 is flocculated in the groove 24 while advancing in the direction of the arrow, resulting in the formation of a solid bed b composed of a plurality of resin particles 19 in the molten pool r

[0014] In this solid bed b, the particles 19 existing on the outside easily transfer heat, and on the contrary, the particles 19 existing on the inside are difficult to transfer heat, so it takes a long time for all the particles 19 to melt.

Therefore, the heat of the heaters h1 to h3 cannot be efficiently transferred to all the resins.

[0015] Also, since a plurality of particles 19 are overlapped in the depth direction of the groove 24 to form a solid bed b, the heat capacity becomes large, and even if shear heat occurs in the resin, as image 3 As shown, the expansion distance L1 until the resin is completely melted becomes longer

[0016] As a result, the screw 14 needs to be lengthened by the corresponding amount, and the heating cylinder 11 also needs to be lengthened accordingly. Therefore, not only the axial dimension of the injection device becomes larger, but also when the screw 14 is maintained and managed or when the screw 14 is replaced, the screw 14 is damaged. The thrusting work becomes difficult

[0017] In addition, since the surface area of ​​the heating cylinder 11 is increased, the amount of heat released is increased, which not only lowers the energy efficiency, but also heats the resin uselessly, so that ablation of the resin occurs, that is, resin ablation

In addition, contrary to the case where the particles 19 present on the outside are sufficiently melted, the particles 19 present on the inside are not sufficiently melted, and, as the solid bed b advances in the tank 24, a large amount of the particles 19 are mainly melted by shearing heat. , so the resin cannot be melted uniformly

As a result, the quality of molded products deteriorates

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