JPH0111452Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention heats and fluidizes plastic materials,
It relates to an injection molding apparatus used when molding plastic material by pushing it into a mold, and particularly relates to an injection molding apparatus equipped with a feed screw that supplies plastic material from a raw material hopper to a feed zone of a screw at a constant supply rate. .

(Prior Art) There are two types of injection molding apparatus: one without a feed screw, as shown in FIG. 1, and the other with a feed screw, as shown in FIG. In the former case, as shown in FIG. 1, a raw material hopper c is directly connected to a heating cylinder b into which a screw a is rotatably inserted and reciprocated, and the plastic material fed into the hopper c is is the feed zone F of the screw a directly from the discharge end of the hopper c.
It is now being supplied to In this example, since the amount of plastic material discharged from the hopper c is not controlled, the opening d made in the heating tube b will be filled with plastic material, and therefore during the plasticizing process. The generated gas etc. cannot flow into the opening d of the heating tube b.

As shown in FIG. 2, the latter device generally includes a heating cylinder 2 for plasticizing plastic material and storing the plasticized plastic material 1, and a heating cylinder 2 inserted into the heating cylinder 2 so as to be rotatable and reciprocating. a feed screw 5 which is provided between the raw material hopper 4 and the heating cylinder 2 and which supplies a constant supply amount of plastic material to the feed zone F of the main screw 3; The supply cylinder 6 has a supply port 5A and a discharge port 5B, and the discharge end of the raw material hopper 4 is connected to the supply port 5A. At the same time, one end of a connecting tube 7 is connected to the discharge port 5B, and the other end of the connecting tube 7 is connected to an opening 8 formed at the base end of the heating tube 2. A feed zone F of the screw 3 immediately after injection, that is, at the most advanced position, is located below this opening 8.

The plastic material charged into the raw material hopper 4 is transferred toward the discharge port 5B by the rotating feed screw 5, and a certain amount of plastic material falls into the connecting cylinder 7 from the discharge port 5B.
The fallen plastic material is supplied from the opening 8 of the heating cylinder 2 to the feed zone F of the main screw 3, and further sent to the tip of the heating cylinder 2 by the rotating screw 3, where it is stored and weighed. .

However, the inside of the heating cylinder 2 is at a fairly high temperature because it is necessary to plasticize the plastic material. Therefore, gas and residual monomer are generated in the plasticizing process of the plastic material, and the plastic material is also heated. The moisture in the water turns into steam, and these generated gas and steam pass through the heating cylinder 2 through the main screw 3.
move in the direction of feed zone F. Since the temperature near the feed zone F is lower than that at the tip of the heating cylinder 2, the gas flowing toward the feed zone F condenses and adheres to the newly supplied plastic material, causing molding. This had an undesirable effect on the product.

(Purpose of the invention) In view of the above-mentioned problems, the present invention attempts to obtain good molded products by making it possible to degas the gas generated during the plasticizing process of plastic materials before injection. .

(Structure of the invention) In the present invention, a main screw is rotatably inserted into a heating cylinder that plasticizes plastic material and stores the plasticized plastic material, and a space between the heating cylinder and a raw material hopper is provided. A feed screw is provided for supplying a constant supply amount of plastic material to the feed zone of the main screw, and the feed screw is connected between a rotatably installed supply cylinder and the heating cylinder, and the feed screw is connected to the heating cylinder. providing a connecting tube that guides the plastic material discharged from the tube to the feed zone of the feed screw;
A truncated cone-shaped deflecting portion having a through hole communicating with the discharge port of the supply tube is formed on the inner circumferential surface of the connecting tube, and between the outer circumferential surface of the deflecting portion and the inner circumferential surface of the connecting tube. A gas inflow path is formed in which the gap between these becomes narrower as it goes upward, and one end is open facing the upper part of the deflection part, and the other end is open to the other end of the communication path, so that the inside of the connecting cylinder is connected to outside air. By radially forming deaeration holes in the peripheral wall of the connecting cylinder that are slanted upward, the plastic material fed into the raw material hopper enters the supply cylinder from the same hopper, where it is directed in the direction of the connecting cylinder by the feed screw. A certain amount of plastic material will be supplied to the feed zone of the main screw through the connecting tube, and the plastic material supplied to the feed zone will be transferred by the main screw toward the tip of the heating tube. While being transported, the gas is plasticized and stored and measured, and the gas generated at this time moves toward the feed zone of the main screw and flows out through the degassing hole that opens at the top of the deflector.
If the distance between the inflow path between the inner circumferential surface of the connecting tube and the outer circumferential surface of the deflecting portion is set small, the plastic material cannot flow into this inflow path, so the plastic material will not be sucked through the degassing hole. .

(Embodiments) The present invention will be described below with reference to embodiments shown in the drawings. In FIGS. 3 and 4, the same reference numerals as in FIG. 2 indicate the same or corresponding parts. As shown in FIG. 3, a connecting portion 6A protrudes from around the discharge port 5B of the supply tube 6 in a direction perpendicular to the axial direction of the supply tube 6, and one end of the connecting tube 10 is connected to the connecting portion 6A. The other end is connected around an opening 8 formed in the heating cylinder 2.

The connecting tube 10 has a deflecting portion 11 having a truncated conical outer shape on its inner circumferential surface. This deflecting part 11 has a through hole 12 having a similar outer shape, and is arranged such that the end face with a larger diameter among the two end faces of the deflecting part 11 is located on the supply cylinder 6 side. . The inner peripheral surface 12A of the through hole 12 is connected to the connecting cylinder 1.
0, and the inner circumferential surface of the connecting cylinder 10 is approximately equal to the slope of the inner circumferential surface 12A of the through hole 12. In other words, the connecting tube 1
The hole defined by the inner circumferential surfaces 10A and 12A of the through hole 12 and the through hole 12 has a substantially trapezoidal cross section.

Furthermore, as shown in FIG. 4, on the peripheral wall of the connecting cylinder 10, a plurality of radially arranged holes are arranged, one end opening near the base of the deflecting part 11 and the other end opening on the outer peripheral surface of the connecting cylinder 10. A deaeration hole 13 is provided. The deaeration hole 13 is inclined such that the other end is located higher than the one end, and the deaeration hole 13
The inner circumferential wall 13A on the side of the supply tube 6 is continuous with the outer circumferential surface 11A of the deflecting portion 11. In other words, one end of the deaeration hole 13 is connected to the outer circumferential surface 11A of the deflecting portion 11.
and the inner circumferential surface 10B of the connecting cylinder 10 on the side of the heating cylinder 2. Therefore, the deflecting part 11
The end face on the smaller diameter side is located below one end of the degassing hole 13. Note that the through hole of the deflecting portion 11 and the hole of the connecting cylinder 10 are arranged coaxially.

Further, as described above, the connecting tube 10 is attached to the outer circumferential surface of the heating tube 2 so that the inner circumferential surface 10B at the other end surrounds the opening 8 formed in the heating tube 2, and one end of the connecting tube 10 is supply cylinder 6
It is attached to a flange 14 formed at the end of the connecting cylinder 6A. In the figure, reference numeral 15 denotes an annular attachment part screwed onto the outer periphery of the heating cylinder 2.
0, and is provided adjacent to the circumferential surface of the connecting cylinder 10.
is fixed to the mounting portion 15 with bolts (not shown) or the like. Further, 16 is a bearing that rotatably holds the feed screw.

In this configuration, when plastic material is introduced from the raw material hopper 4 while heating the heating cylinder 2 and rotating the main screw 3 and feed screw 5, the plastic material flows from the discharge end of the hopper 4 through the supply port 5A. A certain amount of plastic material enters the supply tube 6 by the feed screw 5 toward the discharge port 5B, drops from the connecting portion 6A into the connecting tube 10, and then passes through the opening 8 into the main screw 3. The plastic material that has reached the feed zone F is transferred to the tip of the heating cylinder 2 by the rotation of the main screw 3, and during this transfer process, the plastic material is plasticized. The gas generated during this plasticizing process is removed from the opening 8.
The gas moves in the direction and flows into the connecting cylinder 10 from the opening 8, and the gas that further flows into the connecting cylinder 10 is connected to the outer circumferential surface 11A of the deflecting part 11 and the connecting cylinder 1.
The air flows into the degassing hole 13 connected to a vacuum pump (not shown) through an annular inflow path 17 formed between the inner circumferential surface 10B of the air filter 10 and the inner circumferential surface 10B of the cylinder 0, and flows out to the outside from the other end.

(Effects) As is clear from the above, in the present invention, since the connecting tube is provided with deaeration holes, gas generated during plasticization of the plastic material flows into the connecting tube from the feed zone side of the main screw. However, it will also flow out from the degassing hole, and therefore, as in the conventional example, relatively high temperature gas will stay at the base of the heating cylinder, condense, and adhere to the newly supplied plastic material. As a result, good molded products can be obtained.

In addition, the deflecting portion 11 has a truncated conical shape.
Since the gas inflow path 17 is formed between the outer peripheral surface of the heating cylinder 1 and the inner peripheral surface of the connecting cylinder, the gas flowing out from the heating cylinder 2 is efficiently collected in the inflow path 17, and therefore efficiently. Can be degassed.

Furthermore, since the deaeration hole opens into the inflow path between the outer circumferential surface of the deflector and the inner circumferential surface of the connecting cylinder, if the distance between the inflow paths is set small, the plastic material will not be able to flow into this inflow path. Therefore, even if a vacuum pump or the like is connected to the degassing hole 13 to evacuate the inside of the connecting cylinder, the plastic material will not be sucked into the degassing hole.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing a conventional device, FIG. 3 is a cross-sectional view showing essential parts of the device according to the present invention, and FIG. 4 is a plan view of a connecting cylinder. 2... Heating tube, 3... Main screw, 4... Raw material hopper, 5... Feed screw, 6... Supply tube, 10... Connecting tube, 11... Deflection part, 13...
...Deaeration hole.

Claims (1)

[Scope of Claim for Utility Model Registration] A main screw is inserted into a heating cylinder that plasticizes plastic material and stores the plasticized plastic material so that it can rotate and reciprocate, and between the heating cylinder and a raw material hopper, A feed screw is provided for supplying a constant supply amount of plastic material to the feed zone of the main screw, and the feed screw is connected between a rotatably installed supply cylinder and the heating cylinder, and A connecting cylinder is provided to guide the discharged plastic material to the feed zone of the screw, and on the inner peripheral surface of the connecting cylinder,
A truncated cone-shaped deflecting portion having a through hole communicating with the outlet of the supply tube is formed, and as the distance between the outer circumferential surface of the deflecting portion and the inner circumferential surface of the connecting tube increases upward, A degassing hole is formed in the connecting tube to form a narrow gas inflow passage, one end of which opens toward the upper part of the deflecting portion, and the other end of which opens to the outer circumferential surface of the connecting tube to communicate the inside of the connecting tube with outside air. An injection molding device that is formed on the peripheral wall of a cylinder in a radial shape that slopes upward.