JPH0152169B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a plastic molding screw used in an injection molding machine, an extrusion molding machine, or the like.

In an injection molding machine, the screw moves backward during metering operation, so the effective screw length becomes shorter.

For this reason, heat generation due to shearing differs, and among the measured resins, the resin temperature tends to be relatively high on the nozzle side and low on the rear side. In addition, a decrease in resin temperature tends to cause insufficient kneading.
This problem is caused by the fact that the molten resin and the solid resin are mixed and discharged during the process from the feed zone where the solid phase is transferred while being preheated to the compression zone and metering zone where the molten phase is formed.

[Prior art]

In order to solve these drawbacks of injection molding machines and to improve the kneading performance and plasticizing performance of extrusion molding machines, various sub-flight screws have been proposed. FIG. 9 is an example of a sub-flight screw, and as shown in the figure, the lead angle of the sub-flight 12 is generally different from that of the main flight 11. For this reason, it is difficult to automate the screw manufacturing process and the process must be carried out by hand. Machining using a flight grinder, which has recently become mainstream, is particularly difficult and expensive.

[Purpose of the invention]

The present invention eliminates these drawbacks, and its purpose is to reduce costs by making the lead angles of the main and sub-flights the same, while achieving the same plasticizing performance and uniform kneading as in the case of screws with different lead angles. An object of the present invention is to provide a screw for plastic molding having high performance.

[Key points of the invention]

The screw for plastic molding of the present invention has a main flight and a sub-flight, and the sub-flight is connected to the main flight at almost right angles at both ends of the part parallel to the main flight and its starting point and its ending point. The height of the sub-flight in the part parallel to the main flight is lower than the main flight, and the height of the sub-flight is even lower than the height of the sub-flight in the part parallel to the main flight. .

[One embodiment of the invention]

The present invention will be explained below with reference to FIGS. 1 to 6 showing one embodiment. Figure 1 is Skrill 2
1, the right side is the inflow side and the left side is the outflow side. A sub-flight 23 is provided in the middle of the main flight 22, and the lead angles of both flights 22 and 23 are the same. The tip of the inflow side of the secondary flight 23 turns to the right at an almost right angle and connects to the main fly 22 as a section 24, and the tip of the outflow side turns to the left at an almost right angle and connects to the main flight 22 as a section 25. Connected. As shown in FIG. 2, which is a developed view of the sub-flight 23, the sub-flight 23 has a closed shape with respect to the flow of resin (not shown) by means of bridges 24 and 25.

As shown in FIG. 3, the height of the secondary flight 23 is constant, and the height of the main flight 22 and the secondary flight 23 are constant.
The clearances δ ₁ to δ ₄ between the cylinders 24 and 25 with respect to the heating cylinder 26 are as follows: δ ₁ <δ ₂・δ ₂ <δ ₃・δ ₂
<
Set δ ₄・δ ₃ = δ ₄ . Alternatively, as shown in FIG. 4, the secondary flight 31 has a slope in which the top gap is δ ₅ on the inflow side and δ ₆ on the outflow side, that is, the top height is lower on the inflow side, and If the gap between the two ends is δ ₇ and the gap between the outflow side 33 is δ ₈ , then δ ₁ <
It is also possible to set δ ₅ · δ ₁ < δ _{6 ·} δ ₅ < δ 7 · δ ₆ < δ ₈ .

The shapes of sections 24, 25 and 32, 33 (24 will be explained below) are as shown in FIG.
Tangent lines are drawn from the valley diameters on both sides of the screw 21 surrounding the weir 24, and the top of the weir 25 is rounded at a position lower than the top of the sub-flight 23.

Alternatively, as shown in FIG. 6, the tangent lines may be connected by a circular arc having a large curvature R'.

The screw 41 shown in FIG. 7 is a multi-stage version of the sub-flight 42, and a developed view of the sub-flight 42 is shown in FIG. The height relationship between the main flight 22 and the sub-flight 42 is the same as in the first embodiment.
2 is lower than that of the main flight 22.

Also, the inflow side flight 43, the outflow side flight 44, the middle flight 45 as a multi-stage type, and the sub-flight 42.
The relationship between the heights of the sub-flight 42 and In some cases, the height of the flight section 42 is made to be a slope that is low on the inflow side and high on the outflow side, and the height of each of the bridges 43 to 45 is made lower than that of the sub-flight 42 in that part.

As shown in FIGS. 5 and 6 of the first embodiment, the cross-sectional shape of the guides 43 to 45 is as follows. The tops of the weirs 43, 44, and 45 are made into an R shape at a low position, or are connected by a circular arc with a large curvature from the tangent line.

〔Effect of the invention〕

As explained above, in the plastic molding screw of the present invention, the sub-flight consists of a part parallel to the main flight and a part bent at a substantially right angle from both ends of this parallel part and whose tip is connected to the main flight, and the sub-flight is parallel to the main flight. The height of the part is lower than the main flight, and the height of the wing is even lower than the parallel part. With this configuration, the seki allows only the molten resin to pass through and blocks the solid resin, which improves the uniformity of the resin without mixing the solid resin into the molten resin, and also makes the resin temperature uniform, improving kneading performance. It also has excellent dispersibility of pigments, etc. Furthermore, since the height of the cross section is lower than that of the parallel section, it has many advantages such as relatively easy color and resin changes.

[Brief explanation of drawings]

Figures 1 to 6 show one embodiment of the present invention, Figure 1 is a side view of the main part of the screw, Figure 2 is a developed view of the secondary flight in Figure 1, and Figures 3 and 4 are Figure 2. 5 and 6 are cross-sectional views of different states taken along the line 5-6 of FIG. 1, and FIG. 7 is a side view of main parts in another embodiment of the present invention. 8 is a developed view of the sub-flight of FIG. 7, and FIG. 9 is a side view of essential parts of the conventional screw. 21,41...Skuriyu, 22...Main flight, 23,42...Secondary flight, 24,25,4
3, 44, 45... Seki.

Claims (1)

[Claims] 1. In a screw having a main flight and a sub-flight, the sub-flight is substantially perpendicular to the main flight at both ends of the part parallel to the main flight, its starting point and its ending point. The height of the secondary flight in the part parallel to the main flight is lower than the main flight, and the height of the secondary flight is even lower than the height of the secondary flight in the part parallel to the main flight. Screw for plastic molding. 2. In a shepherd connected to the main flight at a nearly right angle, the shape of the bottom surface of the groove adjacent to the shear passes through one end of the top surface of the shear on at least one of the upstream and downstream sides, and The screw for plastic molding according to claim 1, characterized in that the screw is a straight line or a circular arc tangent to the circumscribed circle of the bottom surface. 3. The screw for plastic molding according to claim 1, wherein the height of the sub-flight gradually increases toward the downstream side.