JPH0523178B2 - - Google Patents

Description

[Detailed description of the invention]

<Technical field to which the invention pertains> The present invention relates to a screw for a vent-type injection molding machine. <Prior art and its disadvantages> As shown in Fig. 3, the screw of a conventional vent type injection molding machine has a first stage A in which a mixing part 1 such as a dalmage is provided in a measuring part a, and a vent port 2 is open. It consists of a full-flight second stage B, and a feeder device 3 is installed in the heating cylinder of the injection molding machine to adjust the amount of material fed so that the amount of material transferred in the first stage A does not exceed that of the second stage B. It is provided. However, in conventional screws, gelation of the material in the first stage A often occurs too much, and the amount of material fed from the first stage A exceeds the feeding capacity of the second stage B, which tends to cause vent-up. This excessive gelation of the material in the first stage A can be improved to some extent by lowering the temperature setting of the first stage A, and the above-mentioned vent-up can also be prevented by suppressing the amount of material supplied to the feeder device 3. Although it is possible to prevent this to some extent by controlling the screw rotation speed, feeder rotation speed, screw back pressure, etc. while observing the This is disadvantageous in terms of cost. Furthermore, a decrease in plasticizing ability due to torque over due to flow resistance in the mixing section 1, heat generation due to friction heat, and a reduction in the feeder rotation speed was unavoidable. Furthermore, in the second stage B, poor material feeding causes material retention, burnt material, waste defects, color changes, and material change defects. Furthermore, since the second stage B is in full flight, problems such as passage of unmelted material, uneven material temperature, poor kneading, and poor dispersion are likely to occur. <Means for solving the problem> In order to eliminate the above-mentioned drawbacks, a first stage and a second stage consisting of a supply section, a compression section and a metering section are provided.
In the screw of a vent type injection molding machine consisting of stages, each of the first stage and the second stage has one sub-flight between the main flights, and the sub-flight of the first stage is located in the measuring section. The screw for the vent type injection molding machine is characterized in that the screw groove formed by the sub-flights is open at the entrance and exit. Further, the sub-flights of the second stage are located in the metering section or the compression section, and have one or two pitches, and the screw grooves formed by the sub-flights are open at the inlet and outlet thereof,
The valley diameter part was shaped to smoothly rise to the outer diameter of the subflight or to a position slightly lower than the outer diameter of the subflight, and was used as a screw for a vent type injection molding machine. <Function> With the above-described configuration, the plasticizing ability, kneading and dispersibility are improved, and there is no need to use a feeder device, thereby improving operability and reducing costs. It also improves color and material changes. <Embodiment> Next, an embodiment of the present invention will be described with reference to FIG. 1. Reference numeral 10 is a screw for a vent-type injection molding machine, and a first stage A includes a supply section 11, a compression section 12, and a metering section 13; The second stage B also includes a supply section 14, a compression section 15, and a metering section 16. 17 is a main flight, and 18 is a sub-flight provided in the first stage A. 19
is a sub-flight provided in the second stage B.
The two sub-flights 18 and 19 are provided in the measuring sections 13 and 16, respectively, and the screw grooves at the inlets 18a, 19a and the outlets 18b, 19b are in an open state with a length of one pitch. The length of the screw is 1 pitch or 2 pitches (1 pitch in this example) so that the kneading and mixing of materials is not done as intensely as in the conventional screwdriver, such as Dalmage, and the screw groove does not become a weir, etc. Groove entrance 1
8a, 19a and outlets 18b, 19b are open. In addition, as shown in Fig. 2, in order to produce a kneading effect that is not as strong as that of the conventional mixing part, screw grooves as shown in Fig. It may also be a shape c that swells up to the outer diameter part of the crab subflight or to a slightly lower position than the outer diameter part. The test results for the screw according to the present invention and the conventional screw are shown below. <Test 1> Using a 60φ screw, adjust the screw rotation speed.
200rpm, material used is ABS resin, set temperature 235℃
The plasticizing ability, screw torque and vent-up condition were compared.

[Table] <Test 2> A 60φ screw was used to compare the physical properties of molded products made of HPVC material.

[Table] <Test 3> The results of the purge time, purge resin amount, and old resin retention status in the color change test from material PP (red) to material PP (natural) are shown below.

[Table] <Effects> As can be understood from the above test results, the present invention is superior to conventional screws in all aspects, including plasticizing ability, screw torque, vent-up conditions, resin rise conditions, and resin replacement conditions. It is excellent and the drawbacks listed at the beginning are removed.

[Brief explanation of drawings]

1 and 2 are views showing one embodiment of the present invention, and FIG. 1 is an overall view of the screw. Figure 2 is a cross-sectional view of Figure 1. FIG. 3 is an explanatory diagram of a conventional screwdriver. A...1st stage, B...2nd stage, 11,
14... Supply section, 12, 15... Compression section, 13, 16
...Measuring section, 17...Main flight, 18, 19...Sub flight.

Claims (1)

[Scope of Claims] 1. At least one location in each of the first stage and the second stage in the screw of a vented injection molding machine consisting of a first stage and a second stage each comprising a supply section, a compression section, and a metering section. There is one sub-light between the main flights, and the sub-flight of the first stage is located in the measuring section and has one or two pitches, and the screw groove formed by the sub-flight is located at the entrance and exit of the sub-flight. A vent-type injection molding machine characterized by being open at the bottom. 2. The sub-flights of the second stage are located in the metering section or the compression section and have 1 or 2 pitches, and the screw grooves formed by the sub-flights are open at their inlets and outlets, and their valley diameters are The screw for a vent-type injection molding machine according to claim 1, characterized in that the screw is shaped to smoothly rise to the outer diameter of the sub-flight or to a position slightly lower than the outer diameter of the sub-flight.