JPS61227003A - Screw for plastic molding equipped with subflight - Google Patents

Abstract

PURPOSE:To enable to have dam flight function and consequently to uniformly melt and knead resin so as to obtain favorable color dispersibility by a structure wherein the depth of a solid bed groove is gradually decreased from the starting point of a subflight in the downstream direction among the solid bed groove and a melt pool groove, both of which are separated from each other by the subflight. CONSTITUTION:A subflight 26 starts at the starting point of a compression zone 23 and ends at the point a little ahead of its end point. The lead angles of the subflight and of a main flight are same as each other. The height of the subflight 26 is a little lower than that of the main flight 25. In addition, the depth of the solid bed groove 28 is gradually increased from the end point of the subflight is the upstream direction and further made coincide with that of the groove of the full flight screw part equipped with no subflight 26 in a metering zone 22 or at the end point of the compression zone 23 at a position 0.3-3 times of a screw diameter in the direction of a screw shaft. Because the lead angles of both flights are same as each other, an NC thread cutting lathe, an automatic thread grinder and the like can be employed for machining the flights.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a screw for an extrusion molding machine, an injection molding machine, a blow molding machine, etc., and particularly to a screw for plastic molding equipped with subflights.

[Prior art]

An example of a conventional screen equipped with sub-flights will be described with reference to FIG. Screw & 11 consists of a main flight 12 and a sub-flight 13 in between, and the right side (upstream side) of the sub-flight 13 is a melt pool groove 14, and the left side is a solid bed groove 15, which is shown on the right side of the figure. The spacing between the sled, dobe, and dove groove 15 becomes narrower from upstream to downstream, thereby providing a dam flight function. However, since the lead angles of both flights 12 and 13 are different, automatic machining with a NO thread cutting machine is impossible, and manual feeding machining is required with a reed, fly basin end mill, etc., so the manufacturing cost is much higher than with a full flight screw. It was expensive. Furthermore, in the case of hardened screws, automatic thread grinding machines cannot be used, so pre-hardening processing has to be performed, resulting in a decrease in precision due to hardening, and correction thereof also results in a significant increase in costs.

[Purpose of the invention]

The present invention eliminates these drawbacks, and its purpose is to:
To provide a screw for plastic molding equipped with a sub-flight that has an appropriate dam flight function, can be used with an NCC screw comb lathe, an automatic screw grinder, etc., and has a low cost.

[Key points of the invention]

The plastic molding screw with sub-flights according to the present invention has three zones from the base of the thread 91 to the tip: a feed zone/completion zone, a John zone, and a metal ring zone, and has three zones in the screw groove formed by the main flights. In a screw equipped with a sub-flight having the same lead angle as the main flight and a slightly lower height than the main flight, the solid bed is divided by the sub-7 light into a sled, a dobe, a do groove and a meltsol groove. The groove depth of the groove gradually decreases downstream from the subflight start point to the subflight end point.

[Embodiments of the invention]

The following Figures 1 to 3 show one embodiment of the present invention.
This will be explained using figures. The screw 21 in FIG. 1 consists of a metering zone 22, a compression zone 23, a metering zone 23, and a feed zone 24 from the left (tip).

Scree! L21 is equipped with a main flight 25 and a sub-flight 26 provided in the middle.The sub-flight 26 starts from the start point of the composite zone 23 and ends slightly before the end point of the same zone 23, and both flights 25 and 26 have the same lead angle, and the flight height of the sub-flight 26 is slightly lower than that of the main flight 25. The width of the melt pool groove 27 on the right side of the sub flight 26 is narrower than that on the left side of the melt pool groove 28.
The groove depth of No. 7 corresponds to the groove depth of the full-flight screw portion of the feed zone 24 and melt zone 22 which are not provided with the sub-flight 26f.

As shown in Fig. 2, the taper angle of the bottom surface of the warp, dobe, dove groove 28 is larger than that of the melt pool groove 27, so the resin is strongly compressed, and the resin that has undergone crosstalk and dispersion is melted as shown in Fig. 3. As shown in FIG. 3, the melt flows from the solid bed groove 28 over the subflight 26 into the melt pool groove 27, and is kneaded because the bottom surface of this part is gradually becoming shallower. In addition, the groove depth of the solid bed groove 28 gradually increases downstream from the subflight end point as shown in FIG. Either match the groove depth of the full-flight screw part of the metering zone 22 that does not have flights 26, or set this position to the compression zone 23.
One at the end of the line! It's slowing down. This solid bed groove 28
Even in the portion where the groove depth gradually increases, the groove depth is shallower than that of the melt pool groove 27, so crosstalk and dispersion of the resin and promotion of layer formation are carried out. Also, the groove depth of the soliped groove 28 at the end point of the subflight 26 is
6 Groove depth 1/2 of the nori, dobe, do groove 28 at the starting point
It is preferable that it is 14 to 14, and furthermore, it is a sled, a dobe,
The width of the groove in the direction of the screw axis is 1/2 to 7/2 of the total groove width.
Preferably, it is 8.

〔Effect of the invention〕

As explained above, in the plastic molding screw with sub-flights according to the present invention, since the lead angles of the main flights and sub-flights are the same, it is possible to use an NCC screw comb lathe, an automatic screw grinder, etc., and the cost is low. low. Furthermore, Nori, dope, divided by sub-flight,
The depth of the groove gradually decreases from the start point of the subflight toward the end point of the subflight toward the downstream of the resin, so it has a dam flight function, which allows the resin to be uniformly melted and mixed, resulting in even better color dispersion. It has the advantage of gaining gender.

[Brief explanation of drawings]

Figures 1 to 3 show one embodiment of the present invention, Figure 1 is a side view, Figure 2 is a developed view of the melt pool groove, groove, dobe, and groove, and Figure X is the subflight. The developed view and FIG. 4 are side views of the conventional example.

Claims (1)

[Scope of Claims] 1) The screw groove has three zones: a feed zone, a compression zone, and a metering zone, and is made up of raw flights. In the screw having slightly lower subflights, of the solid bed groove and the melt pool groove divided by the subflight, the groove depth of the solid bed groove is smaller than the subflight toward the downstream from the subflight starting point. Plastic molding screw with subflights that taper off to the end of the flight. 2) The depth of the solid bed groove at the end point of the subflight is in the range of 1/2 to 1/5 of the depth of the solid bed groove at the start point of the subflight. Plastic molding screw with sub-flights as described. 3) Claim 1 or 2, characterized in that the width of the solid bed groove divided by the sub-flights in the screw axial direction is 1/2 to 7/8 of the total groove width.
Plastic molding screw with sub-flights at the top. 4) The groove depth of the melt pool groove divided by the sub-flights is the same as the groove depth of a full-flight screw not provided with the sub-flights, according to claims 1 to 3. Plastic molding screw with sub-flights. 5) The groove depth of the solid bed groove divided by the sub-flights gradually increases downstream from the end point of the sub-flights, and at a position 0.1 to 3 times the screw diameter downstream in the screw axial direction. 5. A screw for plastic molding equipped with sub-flights according to claim 1, wherein the groove depth matches the depth of a full-flight screw without sub-flights. 6) The groove depth of the solid bed groove divided by the subflight downstream from the start point of the subflight and the end point of the subflight does not include the subflight downstream from the end point of the subflight. The sub-flight according to any one of claims 1 to 5, wherein the point corresponding to the groove depth of the full-flight screw corresponds to the start and end points of the compression zone, respectively. Screw for plastic molding.