JPS61242809A - Screw for thermoplastic resin - Google Patents

Abstract

PURPOSE:To improve kneading and mixing effect and extrusion capacity, by a method wherein a stage is provided with a part which is formed of a first and second stages, possesses a central trough part and a right and left side trough parts on both sides of the central trough part formed with triple flights, makes the right and left trough pats into the same phase in case where a depth of the trough part is varied into the deepest part from the shallowest part and the central trough part is formed so as to vary at a reverse phase. CONSTITUTION:A screw is so constituted that it possesses a first flight 11, a second and third flights 12, 13 which are in a pitch of the first flight 11 and a central trough part 14 and a right and left trough pats 15, 16 formed with those triple flights, forms so that the right and left trough parts 15, 16 are made into the same phase and the central trough part 14 is varied at a reverse phase at the time when a depth varies to B from A when the shallowest part of the trough part from the inside of a cylinder 6 is A and the deepest part of the same is B, and is provided on a first stage 52 or second stage 53 or both the stages further. The total of cross sectional areas of flow paths based on the right and left trough parts 15, 16 is made about identical with the cross sectional area of the flow path based on the central part of the trough part 14. With this construction, kneading and mixing of pellets can be performed effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a screw used in an extrusion molding machine, an injection molding machine, or a blow molding machine (hereinafter referred to as a bottom molding machine) for molding a thermoplastic resin.

[Prior art]

As a conventional screw used in a molding machine, No. 13 has feed zones 34 and 35 on the upstream side and metering zones 36 and 37' on the downstream side, and such a screw 31 increases the extrusion amount as the rotation increases Although this increases, crosstalk and insufficient mixing result in unmelted resin (not shown) being discharged. As an improvement to this, as shown in the first voice diagram,
A screw 42 has been proposed in which a plurality of inclined grooves 41 are provided as a uniform melt zone 40 in the metal ring zone 39 of the stage 38. Although this one system has a high crosstalk and mixing effect, the resin temperature is too high (it is impossible to increase the rotational speed beyond the level required), and the discharge amount was not as high as expected.

[Purpose of the invention]

The present invention was developed from this perspective, and its purpose is to provide a screw for specific thermoplastic resins that improves the cross-crossing and mixing effects of thermoplastic resins and also improves the extrusion ability.

[Key points of the invention]

The screw for thermoplastic resin of the present invention is a screw consisting of a first stage and a second stage, and is formed between a first flight and one pitch of this first flight and has a smaller diameter than the flight. It has a second flight and a third flight, a central valley formed by these three flights, and valleys on the left and right sides of this valley, and the shallowest part of the valley from the inner surface of the cylinder. When the dimension of is AI and the dimension of the deepest part is B, when the depth of the valley changes from person to BK, the left and right valleys are in the same phase, and the center valley is in the opposite phase. It is characterized in that the portion formed to change is provided on the first stage, the second stage, or both stages.

[Embodiments of the invention]

The present invention will be described below with reference to figures showing one embodiment.

First of all, FIG. 1 shows a part of the screw according to the invention in relation to a cylinder. Between one pitch P of the first flight 11 of the screw 10, there is a second flight having a smaller diameter than the first flight 11. 12 and a third flight 13, these three flights 11, 12, and 13 form a central trough 14 and troughs 15, 16 on the left and right sides thereof. Each valley above 1
The dimension of the shallowest part of the distance from the bottom of the valleys 4, 15, and 16 to the inner surface of the cylinder 6 is A, and the dimension of the deepest part = iB, and from the inner surface of the cylinder 6 to the second flight 12 and the 37th light 13. Measurement to top of ft
When C, the relationship between A and C is C≧A.

In the embodiments shown in FIGS. 1, 5, and 6, the phase is reversed. The sum of the cross-sectional areas of the flow passages formed by the left and right valleys 15 and 16 is made equal to the cross-sectional area of the flow passages formed by the central valley 14.

Figures 7(A) and (H) show the case where the shallowest part and the deepest part of the first flight 11 are in three locations, and Figures 8(A) and (B) are the same. A case is shown in which there are four locations, and in this case, the troughs 14 and 15 and 16 are in opposite phase. Figure 9 (A) and (H) are examples in which the shallowest part and the deepest part are two places, troughs 14 to 16.
Both are eccentric circular shapes, and valley s14 and valley 15
・It is arranged in the opposite phase to 16.

1 and 5 and 6, or FIG. 1 and FIG. 7, or FIG. 1 and FIG. 8, or FIG. 1 and FIG. Its special feature is that it is arranged in two stages. That is, the screw 51 in FIG. This is an example in which the screw portion 10 is placed only where the metering zone was, and the screw 71 in the 1st x@ is placed only where the metaling zone of the second stage 53 was. Next, the operation of the above embodiment will be explained. 1 pitch Kannai pellets of 1st flight 11 are Tanibe 15 and 1
6 changes from depth to depth B (twice in one pitch in Figure 1), and when the depth of mano trough 14 changes from B to depth (twice in one pitch in Figure 1). 2 times), a strong compressive force is applied due to the wedge effect between the valley bottom and the cylinder 6, resulting in a reliable kneading action (Fig. 3).

The kneaded and melted resin is forced to cross the gap C at the top of the second flight 12 and the third flight 13 and flows from the shallow A side to the deep B side, and the resin in the valleys 14, 15 and 16 flows. is kneaded.

(Figure 4). Therefore, a screw in which such a screw portion 10 is arranged on a stage has a similar effect.

〔Effect of the invention〕

As explained above, the present invention provides a screw comprising a first stage and a second stage, the first flight and
A second flight and a third flight formed between one pitch of this first flight and having a smaller diameter than the flight, a central valley formed by these three flights, and valleys on the left and right of this valley. and when the dimension f of the shallowest part of the trough from the inner surface of the cylinder is A, and the dimension B of the deepest part is, when the depth of the trough changes from human to BK, The left and right troughs are formed to have the same phase, and the center trough is formed to have an opposite phase, and the A and B portions of the troughs are at least 2 between 1 pitch and have 9 parts. is provided on the first stage, the second stage, or both stages. Therefore, cross-talk and mixing of the pellets can be carried out efficiently.

[Brief explanation of drawings]

FIG. 1 is a partial front view showing an embodiment of a part of the screw according to the present invention, FIG. 2 is an explanatory view showing the same dimensional relationship, FIGS. 3 and 4 are explanatory views showing the same working state, Figures 5 and 6 are cross-sectional views taken along lines v-v and・(B) Hiremanjo-zu, 5th day of practice, 6 drawings 1 + 8 drawings? Mouth piece 1;? 3rd day, 4th figure; + ro figure, 13th figure, piece 14th figure

Claims (1)

[Claims] 1. A screw consisting of a first stage and a second stage, including a first flight and a second flight formed between one pitch of the first flight and having a smaller diameter than the flight. and a third flight, a central trough formed by these three flights, and troughs on the left and right sides of this trough, and the dimension of the shallowest part of the trough from the inner surface of the cylinder. When A and the dimension of the deepest part are B, when the depth of the valley changes from A to B, the left and right valleys are in the same phase, and the central valley is in the opposite phase. A screw for a thermoplastic resin, wherein a variable portion is provided on the first stage, the second stage, or both stages. 2. Claim 1 in which the sum of the cross-sectional areas of the flow passages formed by the left and right valleys is approximately equal to the cross-sectional area of the flow passages formed by the central valleys.
Screw for thermoplastic resin as described in section.