JPH0471818A - Screw for injection molder - Google Patents

Abstract

PURPOSE:To remarkably improve kneading properties by a method wherein two or more sub-flights are provided in compression zone. CONSTITUTION:At compression zone CZ, solid resin transferred from feeding zone FZ is dammed up with a first sub-flight beta1 and molten film is formed between a cylinder 5 and the solid resin in accompany with the rotation of a screw 1 by its strong shearing action. The melting of the surface of the solid resin is rapidly accelerated by the shearing force of the molten film. Further, when the molten resin, which is transferred by getting over the first sub-flight beta1, gets over a second sub-flight beta2, the molten resin receives much more shearing energy developed by the rotation of the screw 1, since the clearance Z2 between a cylinder barrel 5 and the second sub-flight beta2 is smaller than the clearance Z1 between the cylinder 5 and the first sub-flight beta1 and both semi- molten plasticized resin flight channel 3 and molten plasticized resin discharge side flight 4 are shallow, resulting in realizing the complete melting of the resin and consequently the improvement of kneading properties.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a screw for an injection molding machine that can be applied to an injection molding machine or an extrusion molding machine.

[Conventional technology]

4 and 5 show a conventional screw for an injection molding machine, FIG. 4 is a partially cutaway longitudinal sectional view of the screw for an injection molding machine, and FIG. 5 is a developed view of the screw in FIG. 4.

In Fig. 4, the screw l is connected to the supply section FZ and the compression section CZ.
, a metering section MZ, a supply section FZ and a compression section C.
A first sub-flight β branches off from the main flight α at the boundary between the compression section CZ and the metering section MZ and joins the opposing main flight α again at the boundary between the compression section CZ and the metering section MZ; A second sub-flight β2 branches off from the main flight α at the boundary and merges with the main flight α again in the direction of the screw tip.
The structure has the following.

The first sub-flight β1 and the second sub-flight β2 are divided into a resin material supply threaded groove 2, a semi-molten plasticized resin threaded groove 3, and a molten plasticized resin discharge side threaded groove 4, respectively.

Further, the gap between the cylinder barrel 5 and the first sub-flight β in the compression section CZ is always constant from the supply section FZ side to the metering section MZ side, and furthermore, similarly in the metering section MZ, the gap between the cylinder barrel 5 and the first sub flight β is constant. The gap between the cylinder barrel 5 and the second sub-flight β2 is also constant, and the gap between the cylinder barrel 5 and the first sub-flight β1 is larger than that between the cylinder barrel 5 and the second sub-flight β1.
The gap is configured to be larger than the gap between the sub-flights β2.

Now, in FIG. 4, the resin supplied from the hopper 6 to the supply section FZ receives thermal energy from a heater (not shown) and shear energy due to the rotation of the screw 1, and is gradually melted and transferred forward.

In addition, in the compression section CZ, the solid resin is dammed up by the first sub-flight β1, and as the screw 1 rotates, a molten film is formed between the cylinder barrel 5 and the solid resin due to its strong shearing action, and the molten film is sheared. The force rapidly accelerates the melting of the surface of the solid resin. In this way, the molten resin passes over the first sub-flight β1 and is transferred to the semi-molten plasticized resin groove 3. Although the molten resin is further transferred from the semi-molten plasticized resin thread groove 3 to the molten plasticized resin discharge side thread groove 4 over the second sub-flight β2, the gap between the cylinder barrel 5 and the first sub-flight β1 and Regarding the gap between the second secondary flight β2, the gap between the former cylinder barrel 5 and the first secondary flight βO is larger than the latter, and the molten resin that crosses the second secondary flight β2 is further It is subjected to strong shearing forces and is completely melted.

[Problems to be Solved by the Invention] As described above, in the conventional screw for an injection molding machine, the first sub-flight is arranged as a weir between the main flights in the compression section, and the second sub-flight is arranged between the main flights in the metering section MZ. Because the sub-flight is arranged as a weir, the kneading performance is low, and in order to improve the mixability, the cylinder barrel and the first
If the gap between the sub-flight and the second sub-flight is made smaller, there is a drawback that the throughput is reduced.

[Means to solve the problem]

In order to solve such problems, in the present invention,
A screw for injection molding that is rotatably installed in a cylinder barrel so as to be able to move forward and backward, the screw for injection molding comprising a metering section, a compression section, and a supply section from the front end of the screw body toward the retreating section. It is configured as a multiple flight with two or more sub-flight sections.

[For production]

Since the number of sub-flights in the compression section is set to two or more, kneading performance is significantly improved.

〔Example〕

1 to 3 show one embodiment of a screw for an injection molding machine according to the present invention, FIG. 1 is a partially cut away longitudinal sectional view of the screw for an injection molding machine, FIG. FIG. 3 shows the flow state of the resin in each cross section taken along the line A-D in FIG.

The present invention has a first sub-flight β1 and a second sub-flight β2 between the main flights α, and the first sub-flight β1 and the second sub-flight β2 are both main flights in the boundary area between the measuring section MZ and the compression section CZ. The first sub-flight β branches off from α, and merges with the main flight α in the boundary area between the compression part cZ and the supply part FZ,
A case will be described in which the second sub-flight β2 is combined with the main flight α, for example, in a substantially central region of the compression portion cZ.

In addition, the depth of the resin material supply side screw groove 2 and the depth of the molten plasticized resin discharge side screw groove 4 at this time are continuously gradually decreased from the deep groove part to the shallow groove part in the resin injection direction, and the depth is halved. The depth of the molten plasticized resin side thread groove 3 is kept unchanged with respect to the injection direction of the resin, and the first
At the starting point of secondary flight β1 formation, the depth of the resin material supply side screw groove 2 is set to be deeper than the depth of the semi-molten plasticized resin side screw groove 3 (at the same time, the next second secondary flight β2 in the resin injection direction is formed). At the starting point, the molten plasticized resin discharge side thread groove 4
A case where the depth is made deeper than the thread groove 3 on the semi-molten plasticized resin side will be described.

In FIG. 1, the screw 1 has a supply section FZ and a compression section CZ.
, and a measuring section MZ. In addition, a first sub-flight β1 and a second sub-flight β2 are arranged in the compression section CZ, and the first sub-flight β1 and second sub-flight β2 connect the resin material supply screw groove 2 and the semi-molten plasticized resin. It is divided into a thread groove 3 and a thread groove 4 on the melt-plasticizing discharge side.

In addition, the main flight α at the boundary between the supply section FZ and the compression section CZ
The first sub-flight β1 branches off from the main flight α near the center of the compression part C2 and merges with the opposing main flight α again at the boundary between the compression part CZ and the metering part MZ. The configuration includes a second sub-flight β2 that again joins the opposing main flight α at the boundary between the section CZ and the measuring section MZ.

As shown in FIG. 3, if the gap between the cylinder barrel 5 and the first sub-flight β1 in the compression part CZ is Z8, and the gap between the cylinder barrel 5 and the second sub-flight β2 is 72, then the cylinder barrel 5 and The gap Z1 with the first sub-flight β1 is constantly constant from the supply section FZ side to the measuring section MZ side, and furthermore, the gap Z2 between the cylinder barrel 5 and the second sub-flight β2 is also constant, and Z+ >Zz.

Furthermore, regarding the depth of the threaded groove in the compression part CZ,
First, the resin material supply side screw groove 2 has a structure in which the threads gradually decrease in the resin injection direction from the deep groove part to the shallow groove part so that H+>Hz>Hs>Ha.

In addition, the semi-molten plasticized resin side thread groove 3 in the compression part CZ
The depth H3 remains unchanged in the resin injection direction. Furthermore, near the formation start point of the second sub-flight β2 which branches from the main flight α and separates into the semi-molten plasticized resin thread groove 3 and the molten plasticized resin discharge side thread groove 4, the semi-molten plasticized resin side thread groove The depth H6 of the groove on the molten plasticized resin discharge side threaded groove 4 is deeper than the depth H3 of the groove in No. 3 < (H, >Hs)
It has become. In addition, near the formation end point of the second secondary flight β2 where the second secondary flight β2 is combined with the opposing main flight α, the depth H4 of the resin material supply side thread groove 2 described above, the semi-molten plasticized resin side thread The depth H3 of the groove 3 and the depth H6 of the molten plasticized resin discharge side threaded groove 4 are almost the same (H= =H
s = Hb).

The operation of the high kneading screw configured as above will be explained.

In FIG. 1, the resin supplied from the hopper 6 to the supply section FZ receives thermal energy from a heater (not shown) and shear energy due to the rotation of the screw 1, and is gradually melted and transferred forward.

In the compression section CZ, the solid resin that has moved from the supply section FZ is stopped by the first sub-flight β1, and as the screw 1 rotates, a molten film is formed between the cylinder 5 and the solid resin due to its strong shearing action. The melting of the surface of the solid resin is rapidly promoted by the shear force of the molten film.

Furthermore, when the molten resin that has moved over the first sub-flight β1 crosses the second sub-flight β2, the gap Zt between the cylinder barrel 5 and the second sub-flight β2 is
It is smaller than the gap Z1 between the cylinder barrel 5 and the first sub-flight β1 described above, and furthermore, the semi-molten plasticized resin threaded groove 3
Also, since the thread groove 4 on the molten plasticized resin discharge side is shallow,
As the resin receives more shear energy from the rotation of the screw 1, the resin is completely melted and the crosstalk property is improved. In particular, in the present invention, the resin group remaining in the resin material supply thread groove 2 in the compression part CZ, the semi-molten plasticized resin thread groove 3 and the molten plasticized discharge side thread groove 4 is located on the axis of the screw 1. The resin moves smoothly in the direction from the supply section FZ side to the metering section MZ side, and a certain amount of resin sent from the supply group FZ side is blocked by this triple flight section and the extrusion force is stabilized. The quantification is then constant.

In addition, in the embodiment of the present invention, the gap ZI between the cylinder barrel 5 and the first sub-flight β1 in the compression part CZ is replaced by the gap Z2 between the cylinder barrel 5 and the second sub-flight β2.
Although the case where Z1 is made larger has been described, the invention is not limited to this, and almost the same effect can be obtained even if Z1=72.

In addition, in the embodiment of the present invention, the second flight α is provided between the main flights α. A first subsidiary flight of the second thread that branches the third thread and separates it into a resin material supply thread groove and a semi-molten plasticized resin thread groove, and the semi-molten plasticized resin thread groove and the molten plasticized resin. Although we have described a high-kneading screw that has a triple flight consisting of a second sub-flight of a third thread that is separated into a thread groove on the discharge side, the invention is not limited to this. It is also possible to create multiple flights with branches.

Further, in the embodiment of the present invention, the second secondary flight β2
Although the case where the position where the main flight α branches off from the main flight α is approximately near the center of the compression section CZ has been described, the branching position is not limited to this, and may be branched off from any arbitrary position of the compression section CZ.

Furthermore, in this embodiment, the first sub-flight β1 and the second
Although the final merging point where the secondary flight β2 joins the main flight α is set at the boundary between the compression section CZ and the measuring section MZ, the final merging point is not limited to this, and the final merging point can be extended to the measuring section MZ. Good too.

〔Effect of the invention〕

As is clear from the above explanation, in the present invention,
A screw for injection molding that is rotatably installed in a cylinder barrel so as to be able to move forward and backward, the screw for injection molding comprising a metering section, a compression section, and a supply section from the front end of the screw body toward the retreating section. By providing multiple flights with two or more sub-flight sections, cross-talk is significantly improved.

[Brief explanation of the drawing]

Figures 1 to 3 show one of the high kneading screws according to the present invention.
Examples are shown in which Fig. 1 is a partially cutaway vertical sectional view of a high-kneading screw, Fig. 2 is a developed view of the screw, and Fig. 3 is a cross-sectional view of the high kneading screw.
The flow state of the resin in each cross section at point D is shown. 4 and 5 show a conventional high-kneading screw, FIG. 4 is a partially cutaway vertical sectional view of the high-kneading screw, and FIG. 5 is a developed view of the screw in FIG. 4. Machining: Screw, 2: Resin material supply screw groove, 3:
... Semi-molten plasticized resin threaded groove, 4... Molten plasticized resin discharge side threaded groove, 5... Cylinder barrel, 6... Hopper, α... Main flight, β,... 1st sub flight,
β2...Second sub-flight, MZ...Weighing department, CZ.
... Compression section, FZ... Supply section.

Claims (1)

[Claims] A screw for injection molding that is rotatably installed in a cylinder barrel so as to be able to move forward and backward, the screw for injection molding comprising a metering section, a compression section, and a supply section from the front end of the screw body toward the retreating section. A screw for an injection molding machine, characterized in that the screw has multiple flights with two or more sub-flight sections.