JP2001121577A - Injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a frictional resistance to be applied to a resin in an injecting step. SOLUTION: The injection device comprises a heating cylinder 11 having a resin supply port 15 formed at a predetermined position, a screw having a flight part formed with a flight on the outer periphery of a screw body and a screw head arranged on the front end of the flight part to be rotatably arranged in such manner as to be freely advanced and retracted in the cylinder, and a hopper 16 mounted in the port 15 to supply a resin into the cylinder 11. A protrusion 81 protruded toward the port 15 is formed at the front end of the port 15. In this case, he resin dropped form the hopper 16 is deflected toward rearward by the protrusion 81 in the case of passing the port 15. The resin supplied in to the cylinder 11 through the port 15 is prevented from being sandwiched between the flight and the cylinder 11.

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 is provided with an injection device, and a screw is rotatably and advancing and retracting in a heating cylinder of the injection device. It can be rotated and moved forward and backward by an injection motor. Also,
A spiral flight is formed on the screw body, that is, the outer peripheral surface of the screw body, and the flight forms a groove. And during the weighing process,
When the screw is rotated in the forward direction, the resin dropped from the hopper is advanced along the groove while being melted, is stored in front of the screw head, and the screw is retracted accordingly. Also, during the injection process,
By advancing the screw, the resin stored in front of the screw head is injected from an injection nozzle, and is filled in the cavity space of the mold apparatus.

[0003] To this end, a resin supply port is formed at a predetermined position in the heating cylinder, and a resin supply section through which the resin is supplied from the hopper through the resin supply port in order from rear to front. A compression unit for melting the supplied resin while compressing the same and a measuring unit for measuring a fixed amount of the melted resin are formed. The resin in the groove has a pellet-like shape in the resin supply section, becomes a semi-molten state in the compression section, and becomes completely liquid in the measuring section.

By the way, if the outer peripheral surface of the screw and the inner peripheral surface of the heating cylinder have the same roughness, even if the screw is rotated during the measuring step, the resin in the groove is rotated integrally with the screw. Do not move forward. Therefore, usually, the inner peripheral surface of the heating cylinder is made rougher than the outer peripheral surface of the screw.

[0005]

However, in the above-described conventional injection device, the resin dropped from the hopper and supplied to the heating cylinder through the resin supply port is supplied between the flight and the heating cylinder (resin supply). (Near the front end of the mouth), so that when the screw is advanced, a large frictional resistance is applied to the resin near the inner peripheral surface of the heating cylinder.

Accordingly, in the injection step, the injection power applied to the screw from the rear does not correspond to the injection pressure applied to the front end of the screw head, and it is not possible to inject the resin with a sufficient injection pressure. As a result, the resin pressure in the cavity space of the mold apparatus, that is, the internal pressure of the mold also varies, thereby deteriorating the quality of the molded product.

The present invention solves the problems of the conventional injection device, and provides an injection device capable of reducing the frictional resistance applied to the resin in the injection step and improving the quality of a molded product. The purpose is to do.

[0008]

For this purpose, in the injection apparatus of the present invention, a heating cylinder having a resin supply port formed at a predetermined position, a flight section having a flight formed on an outer peripheral surface of a screw body, and A screw head disposed at the front end of the flight section, a screw rotatably provided in the heating cylinder, and a screw disposed movably forward and backward, and attached to the resin supply port, and the resin is supplied into the heating cylinder. And a supply hopper.

[0009] At the front end of the resin supply port, a projection protruding into the resin supply port is formed.

In another injection device of the present invention, the projection has a lower end projecting from an upper end.

[0011]

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

FIG. 1 is a cross-sectional view of a main part of a resin supply port according to an embodiment of the present invention, FIG. 2 is an enlarged view of a main part of an injection device according to the embodiment of the present invention, and FIG. FIG. 4 is a conceptual view of an injection device, and FIG. 4 is a plan view of a resin supply port in the embodiment of the present invention.

In the drawing, 11 is a heating cylinder as a cylinder member, 12 is a screw as an injection member disposed rotatably and advancing and retracting in the heating cylinder 11, and 13 is a front end of the heating cylinder 11. An injection nozzle formed at the left end in FIG. 2, a nozzle opening 14 formed at the injection nozzle 13, and a nozzle 15 formed at a predetermined position near the rear end (the right end in FIG. 2) of the heating cylinder 11. The resin supply port 16 is
Is a hopper that accommodates resin and supplies it into the heating cylinder 11.

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 spiral flight 23 formed on the main body of the screw 12, that is, the outer peripheral surface of the screw main body, and the flight 23 forms a spiral groove 24. The flight unit 21 has a resin supply unit P1 to which the resin dropped from the hopper 16 is supplied through the resin supply port 15 in order from the rear (the right in FIG. 2) to the front (the left in FIG. 2). 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. The bottom of the groove 24, that is, the outer diameter of the groove bottom is made relatively small in the resin supply part P1, gradually increased from the rear to the front in the compression part P2, and made relatively large in the measurement part P3. Therefore, a gap (gap) between the inner peripheral surface of the heating cylinder 11 and the outer peripheral surface of the shaft of the screw 12 is relatively large in the resin supply part P1, and gradually decreases from the rear to the front in the compression part P2. Then, it is made relatively small in the measuring section P3.

When the screw 12 is rotated in the forward direction during the weighing step, the resin dropped from the hopper 16 is supplied to the resin supply section P1, and is advanced (moved to the left in FIG. 2) in the groove 24. The screw 12 is stored in front of the screw head 27, and the screw 12 is moved backward (to the right in FIG. 2) accordingly. The resin in the groove 24 has a pellet-like shape in the resin supply section P1 as shown in FIG. 2, becomes a semi-molten state in the compression section P2, and is completely melted in the measurement section P3. And become liquid.

In the injection step, the screw 12
Is advanced, the resin stored in front of the screw head 27 is injected from the injection nozzle 13 and filled in a cavity space of a mold device (not shown). At this time,
A backflow prevention device is provided around the screw head 27 so that the resin stored in front of the screw head 27 does not flow backward.

For this purpose, the screw head 27
Has a conical (conical) head body 25 in the front half (the left half in FIG. 2) and a column 26 in the rear half (the right half in FIG. 2). An annular check ring 28 is rotatably disposed on the outer periphery of the cylindrical portion 26, and a presser 29 is fixed to the front end of the flight portion 21.

In the check ring 28, holes 28a extending in the axial direction are formed at a plurality of positions in the circumferential direction, and cutouts 28b are formed at a front end thereof at a predetermined angle. Then, a locking projection 25a is formed on the head body 25, and the locking projection 25a is placed in the notch 28b. In this case, the check ring 28 is
With the rotation of the screw head 27, the screw head 27 is rotated by a predetermined angle θ, and further rotation is restricted.

On the other hand, the pusher 29 has holes 29a extending in the axial direction corresponding to the holes 28a at a plurality of positions in the circumferential direction, and the check ring 28 is rotated with respect to the screw head 27. As a result, the holes 28a and 29a are selectively communicated with each other. Accordingly, the check ring 28 has a communication position for communicating the front of the screw head 27 with the flight portion 21 and a blocking position for blocking the front of the screw head 27 and the flight portion 21. The backflow prevention device includes a check ring 28 and a presser 29.

The rear end (right end in FIG. 3) of the heating cylinder 11 is attached to a front injection support 31, and a rear injection support 32 is provided at a predetermined distance from the front injection support 31. A guide bar 33 is provided between the front injection support 31 and the rear injection support 32, and a pressure plate 34 is disposed along the guide bar 33 so as to be able to advance and retreat. The front injection support 31 and the rear injection support 32 are
It is fixed to a slide base (not shown) by bolts (not shown).

A drive shaft 35 is connected to the rear end of the screw 12, and the drive shaft 35
Is rotatably supported on the pressure plate 34 by bearings 36 and 37. An electric measuring motor 41 is provided as a first driving means, and a first rotation transmission means including pulleys 42 and 43 and a timing belt 44 is provided between the measuring motor 41 and the drive shaft 35. The metering motor 41
, The screw 12 can be rotated in the forward or reverse direction. In this embodiment, the electric weighing motor 41 is used as the first driving means, but a hydraulic motor may be used instead of the electric weighing motor 41.

A ball screw 47 composed of a ball screw shaft 45 and a ball nut 46 screwed to each other is disposed behind the pressure plate 34 (to the right in FIG. 3). Motion direction conversion means for converting the motion into a linear motion is configured. The ball screw shaft 45 is rotatably supported by the rear injection support 32 by a bearing 48, and the ball nut 46 is formed by a plate 51 and a load cell 52.
And is fixed to the pressure plate 34 via. Further, an injection motor 53 as a second driving means is provided, and between the injection motor 53 and the ball screw shaft 45,
Since the second rotation transmission means including the pulleys 54 and 55 and the timing belt 56 is provided, the injection motor 53 is driven and the ball screw shaft 45 is rotated to move the ball nut 46 and the pressure plate 34. Then, the screw 12 can be advanced (moved to the left in FIG. 3) or retracted (moved to the right in FIG. 3). In the present embodiment, the injection motor 53 is used as the second driving means, but an injection cylinder may be used instead of the injection motor 53.

When the resin supplied into the heating cylinder 11 through the resin supply port 15 is caught between the flight 23 and the heating cylinder 11, when the screw 12 is advanced, Large frictional resistance is applied to the resin near the inner peripheral surface of the eleventh surface.

In this case, in the injection step, the injection force applied to the screw 12 from the rear does not correspond to the injection pressure applied to the front end of the screw head 27, and the resin cannot be injected with a sufficient injection pressure. As a result, the pressure in the mold is varied, and the quality of the molded product is reduced.

Therefore, the resin supplied into the heating cylinder 11 through the resin supply port 15 is prevented from being caught between the flight 23 and the heating cylinder 11. Therefore, as shown in FIG. 4, the resin supply port 15 has a track-like shape, and has a semicircular portion 71 formed at a front end (left end in FIG. 4) and a rear end (right end in FIG. 4). Semi-circular portion 72 and semi-circular portion 7
It is composed of linear portions 73 and 74 connecting between the first and the second 72. And, as shown in FIG.
On the other hand, the semi-circular portion 71 has a projection 81 projecting rearward (rightward in FIG. 1), that is, projecting into the resin supply port 15. The projection 81 is formed smoothly from the upper end a located on the outer peripheral edge of the heating cylinder 11 to the lower end b located on the inner peripheral edge of the heating cylinder 11, and the amount of projection increases as approaching the lower end b.

In this case, the resin dropped from the hopper 16 is deflected rearward by the projection 81 when passing through the resin supply port 15. Therefore, the resin supply port 1
5 is prevented from being caught between the flight 23 and the heating cylinder 11 when the screw 12 is moved forward. The frictional resistance applied to the resin in the vicinity can be reduced.

As a result, in the injection step, the injection power corresponds to the injection pressure, so that the resin can be injected with a sufficient injection pressure. Further, since it is possible to prevent the variation in the mold inner pressure, it is possible to improve the quality of the molded product.

The present invention is not limited to the above 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.

For example, instead of the backflow prevention device described in the above embodiment, a backflow prevention device in which the check ring moves in the axial direction can be used.

[0030]

As described above in detail, according to the present invention, in the injection device, the heating cylinder having the resin supply port formed at a predetermined position and the flight formed on the outer peripheral surface of the screw body. A flight section, comprising a screw head disposed at the front end of the flight section, a screw rotatably disposed within the heating cylinder, and a screw disposed so as to be able to advance and retreat, attached to the resin supply port, the resin And a hopper for supplying into the heating cylinder.

At the front end of the resin supply port, a projection is formed which projects toward the inside of the resin supply port.

In this case, the resin dropped from the hopper is deflected rearward by the projection when passing through the resin supply port. Therefore, the resin supplied into the heating cylinder through the resin supply port is prevented from being pinched between the flight and the heating cylinder, so that when the screw is advanced, the vicinity of the inner peripheral surface of the heating cylinder is reduced. Frictional resistance applied to the resin can be reduced.

As a result, in the injection step, the injection power and the injection pressure correspond, so that the resin can be injected with a sufficient injection pressure. Further, since it is possible to prevent the variation in the mold inner pressure, it is possible to improve the quality of the molded product.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of a resin supply port according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the injection device according to the embodiment of the present invention.

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

FIG. 4 is a plan view of a resin supply port according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Heating cylinder 12 Screw 15 Resin supply port 16 Hopper 21 Flight part 23 Flight 27 Screw head 81 Projection a Upper end b Lower end

Claims (2)

[Claims] 1. A heating cylinder having a resin supply port formed at a predetermined position, a flight section having a flight formed on an outer peripheral surface of a screw body, and a front end of the flight section. A screw head rotatably and advancing and retreating within the heating cylinder, and (c) a hopper attached to the resin supply port and supplying resin into the heating cylinder. And (d) a projection formed at the front end of the resin supply port, the protrusion protruding into the resin supply port. 2. The injection device according to claim 1, wherein a lower end of the projection is projected from an upper end.