JPS642496B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a screw used in a molding machine such as an injection molding machine or an extrusion molding machine.

[Technical background of the invention and its problems]

Screws used in injection molding machines generally have a feed zone that transports the solid phase of the material while preheating it, a compression zone that forms the molten phase of the material, and a meter that measures the molten material, from the base side to the tip. It is a ring zone, and the supplied solid material is preheated, melted, measured, and then supplied from the tip to the mold side.

By the way, in screws for plastic injection molding, the effective length of the screw is shortened due to the backward metering operation, so generally the resin temperature is relatively high on the nozzle side of the resin being metered, and the resin temperature of the resin metered at the rear is relatively high. tends to be lower.

When the resin temperature decreases in this way, a problem arises in that insufficient kneading is likely to occur.

These problems arise because a melt pool and a solid bed coexist and are discharged from the feed zone, where the solid phase is preheated and transported, to the compression zone, where the molten phase is formed, and the metering zone. For this reason, various improvements have been proposed in which the screw is provided with auxiliary flights with the intention of separating the solid bed from the melt pool and heating and melting it at an early stage.

Namely, (1) one in which an auxiliary flight is provided along and parallel to the main flight in the compression zone area of the screw (Utility Model Application Publication No. 53-96070); (2)
An auxiliary flight that branches off from the main flight and continues to the main flight on the AC side (Jikko 55-
18180), and (3) one with an auxiliary flight having a lead angle different from the main flight (Japanese Unexamined Patent Publication No. 1983-59159).

However, in all of the screws mentioned above, the auxiliary flight is generally longer than the main flight, and they are manufactured either by maintaining the lead or by changing the lead angle, which both have the disadvantage of significantly increasing manufacturing costs. In (2) and (3) above, in which the lead angle of the auxiliary flight is different from that of the main flight, there is a problem that resin accumulates near the start and end of the auxiliary flight, causing retention burn. be.

[Purpose of the invention]

The present invention has been made to eliminate the above-mentioned drawbacks of the prior art, and its object is to provide a screw for plastic molding that can further improve uniform plasticizing performance and uniform kneading performance of materials.

[Summary of the invention]

To achieve the above object, the present invention provides an injection molding system having a feed zone for preheating and transferring the solid phase of the material from the base side to the tip, a compression zone for forming the molten phase, and a metering zone for metering the molten phase. In a screw used in a molding machine, etc., at least one of the zones has a circumference that has a smaller lead angle than the main flight of the zone and whose starting end is from the back of the main flight and whose end is close to or in contact with the front of the main flight. It is characterized by providing an auxiliary flight whose length in the direction is 1 pitch to 2 pitches.

[Embodiments of the invention]

The present invention will be described below with reference to embodiments shown in the drawings.

The auxiliary flight 2 of the screw 1 according to the invention comprises:
The length in the circumferential direction is short, about 1 to 2 pitches, and the starting end 2A of this auxiliary flight 2 starts from the back of the main flight 3, and the terminal end 2B starts from the back of the main flight 3.
The lead angle is smaller than that of the main flight 3.

To explain a specific example of how to provide the auxiliary flight 2, FIG. 1 shows a case where the auxiliary flight 2 is provided in the feed zone of the screw 1, and the starting end 2A of the auxiliary flight 2 is connected to the main flight at the starting end of the feed zone. Narrow gap L to the back of 3
2, the terminal end 2B ends with a narrow gap 1 to the front surface of the main flight 3, and the terminal end 2B and the rear surface of the main flight 3 are separated by a wide distance L1.

Further, the height of the auxiliary flight 2 is formed to be lower than the main flight 3 by an amount H.

Figure 2 shows the case where the screw 1 of the auxiliary flight 2 is installed in the compression zone.
The figure shows the case where it is installed in a metering zone. FIG. 4 shows the case where the feed zone, compression zone, and metering zone are provided. In each of the examples shown above, the configuration of the auxiliary flight 2 is the same as that shown in FIG. 1 above. FIG. 5 shows the flow of the molten resin 6 by developing the relationship between the auxiliary flight 2 and the main flight 3.

Therefore, according to the screw according to the present invention, as shown in FIG.
The auxiliary flight 2 is sent forward over the mountain of the auxiliary flight 2 which is lower by a height H than that of the molten resin 6, and aims to uniformly plasticize the molten resin 6, improve the kneading performance, and the dispersion performance of pigments etc. by the shearing action by the dam function. I can do it. In this case, depending on the properties of the resin material, the dimensions L1, 1, L
2 (lead angle), the above performance can be further improved.

In addition, as another modified embodiment, the auxiliary flight 2 may be a feed zone, a compression zone,
Alternatively, it may be provided in the compression zone and the metering zone, or in the feed zone and the metering zone, or both or either of the starting end 2A and the terminal end 2B of the auxiliary flight 2 may be joined to the main flight 3. Furthermore, a plurality of auxiliary flights 2 may be provided for one zone of the screw 1.

〔Effect of the invention〕

As described above, in the present invention, the auxiliary flight has a smaller lead angle than the main flight and is formed lower than the main flight so that the starting end starts at the back of the main flight and the end ends at the front of the main flight. is sheared by the dam action of the auxiliary flights, which can improve uniform plasticization of the resin, kneading properties, and dispersibility of pigments, etc. The auxiliary flights have a circumferential length of about 1 to 2 pitches. Since the length is short, resin does not stagnate, there is no problem in changing colors or resins, the screws are easy to manufacture, and screws with good performance can be obtained at low cost.

[Brief explanation of the drawing]

1 to 4 are front views showing an embodiment of the present invention, and FIG. 5 is a developed view showing the relationship between one auxiliary flight and the main flight. 1... Skrill, 2... Auxiliary flight, 3...
Main flight.

Claims (1)

[Claims] 1. An injection molding machine or the like having a feed zone for preheating and transferring the solid phase of the material from the base side to the tip, a compression zone for forming the molten phase, and a metering zone for measuring the molten phase. In the screw to be used, at least one of the zones has a lead angle smaller than the main flight of the zone, and a length in the circumferential direction where the starting end is from the back of the main flight and the end is close to or in contact with the front of the main flight. A plastic molding screw characterized by having one to two pitches of auxiliary flights. 2. The plastic molding screw according to claim 1, wherein the height of the auxiliary flight is lower than that of the main flight.