JPH0628260Y2 - Plasticizer screw - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a plasticizing machine screw applicable to a plasticizing machine for plastics, that is, an extruder and an injection molding machine.

(Prior Art) FIGS. 7 to 9 show a conventional general plasticizing screw, and sections E to E show the relationship between the screw 1 and the screw flight 3 when cut at right angles to the screw flight.
Sections F to F show the relationship between the screw 1, the cylinder 2 and the screw flight 3 when cut at right angles to the axis.

Here, the width of the top portion of the flight 3 is designed to be narrow when using a raw material which causes heat generation in the gap δ between the flight 3 and the cylinder 2. That is, the width of the top of the flight 3 is designed to be about 10% of the lead W of a normal flight, about 15% of the lead W of a wide flight, and about 5% of the lead W of a narrow flight. Further, the shape of the top of the flight 3 is a plane, and the clearance δ between the cylinder 2 and the top of the flight 3 is kept constant over the entire length of the screw flight.

(Problems to be Solved by the Invention) When the width of the top portion of the flight 3 shown in FIG. 8 is wide, heat is generated in a gap δ between the screw flight 3 and the cylinder 2. Therefore, in order to prevent this shear heat generation, if the gap δ between the screw flight 3 and the cylinder 2 is increased,
This will increase the leakage flow and reduce the extrusion rate per revolution.

On the other hand, if the width of the top of the flight 3 is narrowed, the surface pressure generated when the screw comes into contact with the cylinder is increased, and the wear of the top of the flight 3 is accelerated. As a means for suppressing the wear of the top part of the flight 3, there is a case where a special steel material is built up on the top part of the flight to deal with it, but there is a drawback that the processing requires high cost.

It is also known that as another means for suppressing the wear of the flight top, it can be dealt with by providing a region called a steprant 4 as shown in FIG. However, if this step land area is provided all around the flight of the screw, there still remains the problem of heat generation at the top of the flight, the processing difficulty is very high, and the manufacturing cost is high.

The present invention is intended to solve the above-mentioned problems by providing the step lands at several places instead of the entire circumference as in the conventional case.

(Means for Solving the Problems) For this reason, the present invention provides a plastic plasticizer having a screw to be inserted into a cylinder and having a feed part, a compression part, and a metering part, and a start and end position of the compression part, In addition, the flight tops of the three screws at the tip of the screw are provided with a step land area that is slightly lower than the top of the flight over the same length as the diameter, and this is used as a means for solving the problem. Is.

(Operation) In the present invention, as a means for suppressing the heat generated at the top of the flight, the width of the top of the flight is dealt with, and as a means for preventing the wear of the top of the flight accompanying it, the start and end positions of the compression part, as well as the screw tip This is dealt with by processing the region of the step land 4 on the flight tops of the three screws over a length approximately equal to the diameter. That is, by providing a region called a step land, which is slightly lower than the top of the flight, along the flight, a lubricating pressure that cancels the unbalanced force generated by the rotation of the flight is generated.

(Embodiment) The present invention will be described below with reference to the embodiments of the drawings. Figs. 1 to 3 show a first embodiment of the present invention, in which the width of the top of the flight 3 is 5% of the lead W of the flight 3. The width is narrowed so as to have the following width so that heat generated between the top of the flight 3 and the cylinder 2 can be suppressed. Further, in a plastic plasticizer having a feed section, a compression section, and a metering section, the start and end positions of the compression section, as well as the screw tip 3
By providing the region of the step land 4 which is a region slightly lower than the top of the flight 3 provided along the flight 3 at the top of the flight 3 of the screw 1 over the length of the diameter, the flight top is provided. It suppresses the wear of. Y is a processing area of the step land.

4 to 6 show a second embodiment of the present invention. Fig. 4 shows the outline drawing of a normal single screw.
The width of the top of flight 3 should be less than 5% of the flight lead and less than half the width X of the root of the flight as shown in FIG. The dimension hs of the step land 4 is 0.5% or less of the bore of the cylinder.

Now, the step land regions Y are provided at three positions of the start and end positions of the compression portion and the tip of the screw, and the length thereof is about the same as the diameter of the cylinder, and the region of the step land 4 is provided. Is provided. The fifth
The width X of the root of the flight and the width of the top of the flight shown in the figure are constant over the entire length of the screw, and differ only in the presence or absence of the region S of the step land 4 in FIG.

(Effects of the Invention) As described in detail above, the present invention has the start and end positions of the compression section, and the flight tops of the three screws at the screw tip, and is slightly longer than the flight top over the same length as the diameter. Since the step land area of the low area is provided,
The metal contact can be avoided by the generation of the lubrication pressure generated in that portion.

Therefore, according to the present invention, heat generated between the screw flight top and the cylinder can be reduced, and at the same time, the flight top wear can be reduced. Moreover, according to the present invention, it is possible to provide a screw that satisfies both the reduction of heat generation and the reduction of wear at a low price.

[Brief description of drawings]

FIG. 1 is a side view of a screw showing an embodiment of the present invention, and FIG.
The drawing is an enlarged sectional view taken along line AA of FIG. 1, and FIG. 3 is taken along line B of FIG.
B is an enlarged sectional view, FIG. 4 is a side view of a screw showing another embodiment of the present invention, FIG. 5 is an enlarged sectional view taken along line CC of FIG. 4, and FIG. 6 is enlarged taken along line D of FIG. Sectional drawing, FIG. 7 is a side view of a conventional plasticizing screw, FIG. 8 is an E-E enlarged sectional view of FIG. 7, and FIG. 9 is an F-F enlarged sectional view of FIG. Description of main parts of the figure 1 …… Screw 2 …… Cylinder 3 …… Screw flight 4 …… Step land …… Flight top width W …… Flight lead Y …… Step land processing area

Claims (1)

[Scope of utility model registration request] 1. A screw, which is inserted into a cylinder,
In a plasticizing device having a feed section, a compression section, and a metering section, the start and end positions of the compression section,
A screw of a plasticizing device is characterized in that a step land region, which is slightly lower than the top of the flight, is provided at the top of the flight of the three screws at the tip of the screw, and the length is about the same as the diameter of the screw.