JP2000334790A - Injection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the outer peripheral face of a flight in a resin feeding part and the inner peripheral face of a heating cylinder from being worn. SOLUTION: A heating cylinder 11 wherein a resin feeding hole is formed at a specified position, a resin feeding part P1 wherein a resin is successively fed from the back to the front through the resin feeding hole, a compression part P2 wherein the fed resin is melted while it is compressed and a metering part P3 for metering the molten resin by a fixed amt., are formed and a screw 12 being freely rotatably and freely forward and backward arranged in a heating cylinder 11 is provided. In addition, the diameter of the bottom face S2 of a channel 24 is made smaller from the back to the front at least at a part of the resin feeding part P1. As the crosssection of the channel 24 is made larger a little with decreasing the diameter of the bottom face S2 of the channel 24, it is possible to prevent pressure in the heating cylinder 11 from becoming higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device.

[0002]

2. Description of the Related Art Conventionally, an injection molding machine has an injection device, and a screw is rotatable in a heating cylinder of the injection device.
And it is arranged so that it can move forward and backward. And during the weighing process,
By retreating while rotating the screw in the forward direction, the resin dropped from the hopper is melted, advanced along the groove of the screw and stored in front of the screw head, and during the injection step, the screw is advanced, The resin stored in front of the screw head is injected from an injection nozzle.

FIG. 2 is a sectional view of a main part of a conventional injection device.

[0004] In the figure, 11 is a heating cylinder,
An injection nozzle (not shown) is formed at a front end (right end in the drawing) of the heating cylinder 11, and a hopper (not shown) is attached to a rear end (left end in the drawing) of the heating cylinder 11. Reference numeral 12 denotes a screw that is rotatably and reciprocally disposed within the heating cylinder 11, and a screw head (not shown) is attached to a front end of the screw 12. Further, on the outer periphery of the screw 12, a spiral flight 23 is provided.
Is formed, and a groove 24 is formed by the flight 23.

In the measuring step, the screw 12 is moved backward (moved to the left in the figure) while rotating the screw 12 in the forward direction by a driving means (not shown), so that the resin dropped from the hopper is melted and The resin stored in front of the screw head is injected by moving the screw 12 forward (moving to the right in the figure) and accumulating it in front of the screw head (right in the figure). Inject from the nozzle.

For this purpose, in the screw 12, a resin supply section P1 to which the resin dropped from the hopper is supplied in order from a rear side (left side in the figure) to a front side, and a compression section to compress and melt the supplied resin. P2 and a measuring section P3 for measuring the melted resin by a fixed amount
Is formed. The resin in the hopper has a pellet-like shape, and the resin supplied to the rear end of the resin supply unit P1 is advanced while maintaining the pellet-like shape, and a predetermined distance from the rear end of the resin supply unit P1. When it reaches a point advanced by a distance (about 50 to 70% of the length of the resin supply unit P1), melting is started. Then, the resin is in a semi-molten state in the compression section P2, is completely melted in the measuring section P3, and is in a liquid state. In the case where a crystalline resin is used as the resin, melting is started when the resin reaches a position advanced by a predetermined distance from the rear end of the resin supply unit P1.

By the way, in the resin supply section P1,
The bottom surface S1 of the groove 24 has a cylindrical shape and is parallel to the axis of the screw 12, and the diameter d1 at the rear end and the diameter d2 at the front end in the resin supply portion P1 are equal.

[0008]

However, in the above-described conventional injection device, the moving speed of the resin is low at a position advanced by a predetermined distance from the rear end of the resin supply section P1 as the resin is melted. Therefore, the melted resin is pressed by the pellet-shaped resin that is moved from behind, and the pressure in the heating cylinder 11 increases. In particular, the more viscous resin used,
The pressure in the heating cylinder 11 increases.

Therefore, when a resin mixed with an inorganic material is used, the inorganic material and the inner peripheral surface of the heating cylinder 11 are strongly rubbed (rubbed).
1, the outer peripheral surface of the flight 23, the inner peripheral surface of the heating cylinder 11, and the like are worn. In addition, when the inorganic material and the inner peripheral surface of the heating cylinder 11 are strongly rubbed, the resin locally becomes high in temperature due to heat generated by shearing, and is deteriorated by oxidation or generates carbide. .
As a result, the quality of the molded product molded by the injection molding machine is reduced.

In the injection device in which the diameter of the bottom surface S1 is gradually increased from the rear to the front of the resin supply section P1, the resin melted by the pellet-shaped resin moved from the rear is used. It is pushed more strongly, and the pressure in the heating cylinder 11 becomes higher.

The present invention solves the above-mentioned problems of the conventional injection device, so that even when a resin mixed with an inorganic material is used, the inorganic material and the inner peripheral surface of the heating cylinder do not rub strongly. An object of the present invention is to provide an injection device capable of preventing the outer peripheral surface of a flight, the inner peripheral surface of a heating cylinder, and the like in a resin supply section from being worn and improving the quality of a molded product.

[0012]

For this purpose, in the injection apparatus of the present invention, a heating cylinder having a resin supply port formed at a predetermined position and a resin supplied through the resin supply port in order from the rear to the front. A supplied resin supply section, a compression section that compresses and melts the supplied resin, and a measuring section that measures the molten resin by a fixed amount are formed,
And a screw disposed rotatably and advancing and retracting in the heating cylinder.

[0013] In at least a part of the resin supply section, the diameter of the bottom surface of the groove is reduced from the rear to the front.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of a main part of an injection device according to a first embodiment of the present invention, and FIG. 3 is a schematic view of the injection device according to the first embodiment of the present invention.

In the drawing, 11 is a heating cylinder as a cylinder member, and 12 is
A screw 13 as an injection member that is rotatably and freely movable forward and backward, 13 is an injection nozzle formed at the front end (left end in FIG. 3) of the heating cylinder 11, and 14 is formed at the injection nozzle 13. A nozzle port 15 is a resin supply port formed at a predetermined position near the rear end (right end in FIG. 3) of the heating cylinder 11, and 16 is a resin supply port 1
5 is a hopper for accommodating pellet-shaped resin.

The screw 12 has a flight section 21,
And a screw head 27 disposed at the front end of the flight section 21. The flight portion 21 includes a flight 23 spirally formed on the outer periphery of the screw body.
And the flight 23 forms a spiral groove 24. The flight section 21 has a resin supply section P1 to which the resin dropped from the hopper 16 is supplied through the resin supply port 15 in order from the rear (left side in FIG. 1) to front side (right side in FIG. 1). A compression section P2 for compressing and melting the supplied resin and a measuring section P3 for measuring the melted resin by a fixed amount are formed.

An injection cylinder 35 is disposed at the rear end of the screw 12 as a driving means for injection, and a piston rod 36 of the injection cylinder 35 and the screw 12 are relatively rotatably connected to each other. . At the rear end of the screw 12, a weighing motor (not shown) as a light-weight driving means is provided, and an output shaft of the weighing motor and the screw 12 are connected by a not-shown transmission means. Note that an injection motor may be used instead of the injection cylinder 35. In the injection device having the above-described configuration, at the time of the measuring step, the measuring motor is driven, and the screw 12 is moved backward (moved to the right in FIG. 3) while rotating the screw 12 in the forward direction.
The resin dropped from the hopper 16 is supplied to the resin supply section P1, is advanced (moves leftward in FIG. 3) along the groove 24, and is stored in front of the screw head 27 (leftward in FIG. 3). The resin in the groove 24 has a pellet shape in the hopper 16, and the resin supplied to the rear end (the left end in FIG. 1) of the resin supply unit P1 has the pellet shape. When it is moved forward and reaches a position advanced a predetermined distance (about 50 to 70% of the length of the resin supply unit P1) from the rear end of the resin supply unit P1, melting is started. Then, the resin is in a semi-molten state in the compression section P2, is completely melted in the measuring section P3, and is in a liquid state.

Subsequently, during the injection process, the injection cylinder 35
By driving the screw 12 to advance the resin, the resin stored in front of the screw head 27 is injected from the injection nozzle 13 to fill the cavity C of the mold device 51. At this time, an annular check ring 28 is rotatably disposed with respect to the screw head 27, and the check ring 28 is moved rearward (to the right in FIG. 3) relative to the screw head 27. In this case, the resin stored in front of the screw head 27 does not flow backward. The mold device 51 includes a fixed mold 31 and a movable mold 32.
The cavity space C is formed between the fixed mold 31 and the movable mold 32.

Incidentally, in the resin supply section P1,
The bottom surface S2 of the groove 24 has a tapered shape such that the diameter decreases from the rear to the front, and the diameter d of the front end (right end in FIG. 1) of the diameter d1 of the rear end of the resin supply portion P1.
3 is small, and from the rear to the front, the bottom surface S
The diameter of 2 is gradually reduced. The compression unit P
2, the bottom surface S3 of the groove 24 has a tapered shape such that the diameter increases from the rear to the front, and the diameter d4 of the front end is larger than the diameter d3 of the rear end in the compressed portion P2,
The diameter of the bottom surface S3 is gradually increased from the rear to the front. Further, in the measuring section P3, the bottom surface S4 of the groove 24 has a cylindrical shape and is parallel to the axis of the screw 12, and the diameter d4 of the rear end and the diameter d5 of the front end of the measuring section P3 are different from each other. equal.

In this case, even if the moving speed of the resin decreases as the resin is melted at a position advanced from the rear end of the resin supply portion P1 by a predetermined distance, the portion moves from the rear to the front of the resin supply portion P1. Since the cross-sectional area between the heating cylinder 11 and the screw 12, that is, the cross-sectional area of the groove 24, is gradually increased by the amount by which the diameter of the bottom surface S2 is slightly reduced, the pellets are moved from the rear. The resin melted by the resin in the shape is not pushed and the pressure in the heating cylinder 11 can be prevented from increasing. And even if a highly viscous resin is used, the pressure in the heating cylinder 11 does not increase.

FIG. 4 is a diagram showing the relationship between the position on the screw and the pressure in the heating cylinder. In the drawing, the position on the screw 12 (FIG. 1) is plotted on the horizontal axis, and the pressure inside the heating cylinder 11 is plotted on the vertical axis.

In the drawing, L1 indicates the pressure in the heating cylinder 11 in the conventional injection device, and L2 indicates the pressure in the heating cylinder 11 in the injection device of the present invention.

In this case, assuming that a position at a certain distance from the resin supply port 15 is SA, the pressure increases as the distance from the position SA increases, and decreases after reaching a maximum value. When the maximum value is P and the maximum value in the injection device of the present invention is P ′, P ′ <P. The pressure does not increase between the resin supply port 15 and the position SA.

Therefore, even when a resin mixed with an inorganic material is used, the inorganic material and the inner peripheral surface of the heating cylinder 11 do not strongly rub against each other. 11 can be prevented from being worn. In addition, since the resin can be prevented from being locally heated to a high temperature due to heat generated by shearing, the resin does not deteriorate due to oxidation and does not generate carbide. As a result, the quality of the molded product molded by the injection molding machine can be improved.

In the present embodiment, the resin supply section P1
Assuming that the cross-sectional area of the groove 24 at the rear end is A1, and the cross-sectional area of the groove 24 at the front end is A2, 1 · A1 <A2 ≦ 1.4 · A1.

Next, a second embodiment of the present invention will be described. In addition, about what has the same structure as 1st Embodiment, the description is abbreviate | omitted by attaching the same code | symbol.

FIG. 5 is a sectional view of a main part of an injection device according to a second embodiment of the present invention.

In this case, in a part of the resin supply portion P1, the diameter of the bottom surface S2 of the groove 24 is reduced from the rear (left side in the figure) to the front side (right side in the figure) to form a tapered portion. In the present embodiment, the tapered portion is formed in front of the position SA in the resin supply portion P1, but the tapered portion is formed in front of the vicinity of the position SA in the resin supply portion P1. Can also.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.

[0031]

As described above in detail, according to the present invention, in the injection apparatus, the heating cylinder having the resin supply port formed at a predetermined position and the resin supply port are arranged in order from the rear to the front. A resin supply unit through which the resin is supplied, a compression unit that compresses and melts the supplied resin,
And a measuring unit for measuring a fixed amount of the melted resin, and a screw rotatably and advancing and retracting in the heating cylinder.

In at least a part of the resin supply section, the diameter of the bottom surface of the groove is reduced from the rear to the front.

In this case, at a position advanced by a predetermined distance from the rear end of the resin supply section, even if the moving speed of the resin decreases as the resin is melted, the above-mentioned resin moves from the rear to the front of the resin supply section. Since the cross-sectional area of the groove is gradually increased by the amount corresponding to the decrease in the diameter of the bottom surface, the molten resin is not pushed by the pellet-shaped resin moved from behind, and the pressure in the heating cylinder is reduced. Can be prevented from increasing. Even if a highly viscous resin is used, the pressure in the heating cylinder does not increase.

Therefore, even when a resin mixed with an inorganic material is used, the inorganic material does not strongly rub against the inner peripheral surface of the heating cylinder. Wear of the surface and the like can be prevented. In addition, since the resin can be prevented from being locally heated to a high temperature due to heat generated by shearing, the resin does not deteriorate due to oxidation and does not generate carbide. As a result, the quality of the molded product molded by the injection molding machine can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of an injection device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a conventional injection device.

FIG. 3 is a schematic diagram of an injection device according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between a position on a screw and a pressure in a heating cylinder.

FIG. 5 is a cross-sectional view of a main part of an injection device according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 11 heating cylinder 12 screw 15 resin supply port 24 groove d1, d3 diameter P1 resin supply section P2 compression section P3 measuring section S2 bottom surface

Claims (1)

[Claims] 1. A heating cylinder having a resin supply port formed at a predetermined position, and (b) a resin supply section to which a resin is supplied through the resin supply port in order from rear to front. Compression unit that melts the compressed resin
And a measuring part for measuring a fixed amount of the melted resin is formed, and a screw is provided in the heating cylinder so as to be rotatable and movable back and forth, and (c) the resin An injection device, wherein the diameter of the bottom surface of the groove is reduced from back to front in at least a part of the supply unit.