JPS60253522A - Preventive nozzle of leakage of resin in injection molding machine - Google Patents

Abstract

PURPOSE:To constitute the titled nozzle so that leakage of resin through the tip of the nozzle can be prevented completely and a pressure loss is little, by constituting the nozzle with a tip constituting an outer shell, a spool forming a flow path of the resin continuing to a flow path of the resin of a main body and a spring which is between the tip and the spool. CONSTITUTION:As the tip part 16 of a flow path 6 of resin is clogged with the inside of a tip the molten resin does not flow. Then as a spool is slided forward against force of a spring through injection pressure, the tip part 16 intrudes into a stop part of the resin and the tip part 16 of the flow path of the resin is released when the injection pressure is applied to the spool by a screw 3 in the inside of a main body at the time of injection action, the molten resin is injected by the injection pressure through an injection opening of a nozzle. As the spool 7 is moved backward through the force of the spring 8 and the flow path of the resin is clogged again when the injection pressure is released after the injection has been completed, a flow of the resin is stopped and leakage of the resin through the injection opening is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a nozzle that does not leak resin from the nozzle tip of an injection molding machine.

[Prior art]

Conventional resin leakage prevention nozzles (generally referred to as pulp nozzles) are published in "Injection Molding" 8th edition No. 270 - supervised by Shoji Seto.
According to page 271, ■Needle nozzle ■Slide nozzle■
It can be classified as a mechanical opening/closing nozzle.

■Needle nozzles have disadvantages such as a complicated structure, large pressure loss due to resistance inside the nozzle, and many places where resin accumulates.

■Slide nozzles are superior to needle nozzles in that they have less pressure loss and stagnation inside the nozzle, but the mold will not close unless the nozzle separates from the mold, so molding must be done with the nozzle still in contact. I can't. Furthermore, when performing nine strokes, the nozzle head must be moved by some external method, which is inconvenient in handling.

■Mechanical opening/closing nozzles are nozzles that forcibly open and close the resin passage through columnar motion or rotational motion, and are the most reliable in operation, but the structure and operation control are complicated. In this way, each structure has advantages and disadvantages.

[Purpose of the invention]

The present invention was completed after various studies to create a nozzle that completely prevents resin leakage from the nozzle tip, which was previously impossible. This invention relates to a resin leakage prevention nozzle.

[Structure of the invention]

The present invention will be explained in detail based on the drawings.

FIGS. 1 and 2 are cross-sectional views of an example of the nozzle for an injection molding machine of the present invention, and FIG.
FIG. 2 is a diagram of the injection operation state.

(1) is the main body of the injection molding machine nozzle, and a resin flow path (2) inside thereof has a screw (3) for cross-directing the molten resin. The nozzle of the present invention (
4) Combine. The nozzle (4) has a chip (5) constituting the outer shell, and a resin flow path (2) that continues to the resin flow path (2) of the main body.
6) and a spring (8) between the tip (5) and the spool (7).

The tip (5) has an injection port (9) at the tip;
9) has a resin fastening part α1 inside. The spool (7) slides with the tip (5) at both ends υ0.

The rear end aυ of the spool (7) and the rear end 0 of the tip are defined as the inner diameter of the rear end (13) of the tip (5) and Main body (11
The outer diameter of the spool rear end αD is larger than the spool outer diameter other than this part, and the tip rear end ←
The width of S (large inner diameter part) is the rear end of the spool aυ (large outer diameter part)
Make the width larger. The difference in both widths corresponds to the sliding length of the spool (7).

The resin flow path (6) in the spool has a nose portion thereof,
The diameter of the resin flow path (2) of the main body is approximately the same as that of the resin flow path (2), and the diameter becomes smaller continuously. It is open on the sliding surface. A spring (8) is fitted between the tip (5) and the spool (7). The spring (8) acts to push the spool (7) backwards.

The injection molding nozzle shown in FIGS. 1 and 2 operates as follows during injection molding. The nozzle before the injection operation is the first
It is in the state shown in the figure. Tip part ae of resin flow path (6)
The molten resin does not flow because it is blocked by the inner surface of the chip. Next, during the injection operation, the screw (3
), as shown in Figure 2, the spool slides forward against the force of the spring due to this injection pressure, and its tip aQ enters the resin fastening part, and the resin Since the tip a0 of the flow path is opened, the molten resin is injected from the injection port of the nozzle due to the injection pressure. When the injection is finished and the injection pressure is removed, the spool (
7) is moved back by the force of the spring (8) and the resin flow path is closed again, so that the flow of resin is stopped and resin leakage from the injection port is prevented (Fig. 1).

In order to prevent damage due to injection pressure, the spool (7) is preferably provided with a side hole αη so that the injection pressure is applied to the tip K. Further, the spring (8) is made of a heat-resistant material so that it can withstand high-temperature injection molding.

〔Effect of the invention〕

The nozzle for injection molding machines of the present invention can completely prevent resin leakage from the nozzle tip and has very little pressure loss, so it can be used especially for molding precision molded products that require high pressure. Therefore, the dimensional variation of the obtained molded product is also reduced. Furthermore, by using this nozzle, metering becomes constant and variations in cylinder temperature are reduced, making it possible to suppress variations in properties of molded products. Furthermore, if a heat-resistant material is used for the spring, the spring will operate well and can be used in high-temperature molding.

[Brief explanation of drawings]

The figures are cross-sectional views of an example of the resin leakage prevention nozzle of the present invention, with FIG. 1 showing a state in which injection is not being performed, and FIG. 2 showing a state in which injection is in operation. 4 Sozzle 5: Tip 7 Spool 8' Spring Figure 1 Figure 2

Claims (1)

[Claims] In the nozzle of an injection molding machine, the chip that constitutes the outer shell,
A spool is located inside the chip and has a resin flow path inside, and a spring is located between the chip and the spool.The spool has an injection port at its tip, and the school The resin flow passage provided inside the nozzle is slidable a certain distance in the axial direction of the nozzle between the spool tip and the spool tip. When the spool advances, it communicates with the injection port through the space inside the tip, and when the spool retreats, it is closed by the sliding surface of the tip.The spool advances due to the injection pressure, and retreats due to the spring. A nozzle characterized in that it operates by the repulsive force of.