JP2001030318A - Injection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely perform first-in first-out operation so as to advantageously mold a resin molded article with no defect on the product and excellent quality. SOLUTION: In this injection apparatus, a plunger 16 is arranged in a hollow part of a hollow cylindrical screw 14 arranged rotatably in a heating cylinder 12 and relatively movably to the heating cylinder 12 so as to pass it through relatively movably to the screw 14 in the axial direction. On the other hand, a storing chamber 50 the inner diameter of which is smaller than the diameter of a site where the screw 14 of the heating cylinder 12 is arranged is provided at the front part in the heating cylinder 12 in such a way that the apex part of the plunger 16 has a size which can run into while a gap 52 between it and the inner peripheral face of the storing chamber 50 is formed by relative movement to the screw 14. In addition, under a condition where the apex part of the plunger 16 runs into the storing chamber 50, a molten resin material is introduced into the storing chamber 50 through the gap 52 and it is stored there.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection apparatus, and more particularly to an injection apparatus constituting an injection molding machine used for molding a resin molded product.

[0002]

2. Description of the Related Art Heretofore, there have been various types of injection devices as described above, one of which is disclosed in
2. Description of the Related Art An injection device having a structure as disclosed in JP-A-84221 is known. That is, in such an injection device, a hollow cylindrical screw is rotatably disposed in a heating cylinder having an injection nozzle at a front end, and a plunger is provided in the hollow portion of the screw with respect to the screw. , The insertion position is relatively movable forward and backward in the axial direction. With the rotation of the screw, the resin material supplied into the heating cylinder is plasticized and melted while being sent forward, and the plunger is increased with the increase in the plasticized and melted molten resin material. Is moved backward in the screw to form a chamber in the screw, and the molten resin material is stored in the chamber.In such a state, the plunger moves through the screw in this state. By being moved forward, the molten resin material stored in the chamber is configured to be injected from the injection nozzle.

[0003] In the injection device having such a structure, as described in the above-mentioned publication, unlike a general in-line screw type injection device, the screw does not move backward with the increase of the molten resin material. Therefore, the wear of the screw can be suppressed, and the relative positional relationship between the screw and the heating zone by the heater of the heating cylinder, and the effective length of the screw do not change significantly, and the molten resin material is in a molten state. The advantage that unevenness does not occur is obtained.

However, in the injection apparatus disclosed in the above publication, the tip surface of the plunger is pressed by the resin pressure of the resin material as the amount of the molten resin increases, and the plunger is moved backward in the screw. By
Since a chamber is formed in the screw and the molten resin material is stored in this chamber, the first supplied molten resin material is placed on the distal end surface of the plunger in such a chamber. It is stored, and the molten resin material supplied later is accumulated sequentially with respect to the previously supplied molten resin material, and the molten resin material supplied last is stored near the injection nozzle, For this reason, what is called first-in first-out cannot be performed, such as injecting first from a molten resin material that is plasticized and melted first and sent to the front of the heating cylinder.

[0005] Therefore, in such a conventional injection apparatus, after the molten resin material stored in the chamber is injected, if the molten resin material remains on the distal end surface of the plunger due to adhesion or the like. Such residual molten resin material, which was initially supplied into the chamber, had a long thermal history, and was further heated in the chamber, so that it could deteriorate and carbonize. In this case, when the deteriorated and carbonized resin material is peeled off from the tip surface of the plunger and is injected together with another molten resin material, the molded resin molded product has a product defect such as poor appearance or insufficient strength. That is, the problem of the occurrence of the problem has been raised.

[0006]

The present invention has been made in view of the circumstances described above, and an object of the present invention is to provide a hollow cylindrical screw rotatably disposed in a heating cylinder. In the injection device, in which the plunger is inserted in the hollow portion so as to be relatively movable in the axial direction with respect to the screw, it is possible to reliably perform first-in first-out, and therefore, it is possible to achieve high quality without product defects. It is an object of the present invention to provide a structure that can advantageously mold various resin molded products.

[0007]

According to the present invention, in order to solve the above-mentioned problem, a hollow cylindrical screw is rotatably provided in a heating cylinder having an injection nozzle at a tip thereof with respect to the heating cylinder. The screw is movably arranged, and a plunger is inserted into the hollow portion of the screw so as to be relatively movable in the axial direction with respect to the screw, and is provided so as to protrude from the tip of the screw. The resin material supplied into the heating cylinder is plasticized and melted while being sent forward by the rotation operation of the screw, and is stored in the front part of the heating cylinder. In an injection device configured to inject from the injection nozzle by a relative movement of the plunger with respect to the screw, the heating cylinder is provided at a front portion in the heating cylinder. A size that allows the distal end of the plunger to enter a storage chamber having an inner diameter smaller than the inner diameter at the screw disposition portion while forming a gap with the inner peripheral surface of the storage chamber by relative movement with respect to the screw. When the tip of the plunger is inserted into the storage chamber, the molten resin material sent forward of the heating cylinder by the rotation of the screw is connected to the outer peripheral surface of the tip of the plunger and the reservoir. The gist of the present invention is also an injection apparatus characterized in that the injection apparatus is configured to be introduced into the storage chamber and stored through the gap between the inner peripheral surface of the chamber and the storage chamber.

In the injection device according to the present invention having such a structure, the injection device is first introduced into the storage chamber through the gap between the outer peripheral surface of the plunger tip and the inner peripheral surface of the storage chamber. Although the molten resin material is temporarily stored on the distal end surface of the plunger, the molten resin material is moved forward by being pushed forward by the molten resin material introduced into the storage chamber thereafter, Then, the molten resin material introduced into the storage chamber later is sequentially accumulated rearward with respect to the molten resin material introduced earlier. As a result, in the storage chamber, the first introduced molten resin material is stored near the injection nozzle at the forefront of the storage chamber, while the last introduced molten resin material is located at the rearmost position of the storage chamber. Thus, the plunger is stored on the tip end surface of the plunger, and it is possible to reliably perform the first-in first-out operation in which the molten plastic material that has been plasticized and melted first is injected first.

Further, in such an injection device, even if the molten resin material stored in the storage chamber is injected and then remains on the distal end surface of the plunger, for example, the molten resin material remains on the distal end surface of the plunger. The molten resin material has the shortest heat history supplied last into the storage chamber, and moves forward through the gap so as to be pushed forward by the molten resin material newly introduced into the storage chamber. It is stored in the vicinity of the injection nozzle at the forefront of the storage chamber.Therefore, in the storage chamber, the resin material deteriorates due to excessive heating for a long time, and no carbonized resin material is present. In a resin molded product molded by injection of a molten resin material in a storage chamber, appearance is deteriorated due to mixing of a deteriorated and carbonized resin material. It and such insufficient strength or the like occurs is, so that the can be effectively avoided.

Therefore, in the injection device according to the present invention, the plunger moves relative to the screw in the axial direction of the hollow cylindrical screw rotatably disposed in the heating cylinder. It is possible to reliably perform first-in first-out while effectively securing the many advantages obtained by having a structure that can be inserted as much as possible, so that a resin molded product of excellent quality without product defects ,
It can be formed very advantageously.

In the injection apparatus according to the present invention, the molten resin material plasticized and melted by the rotation of the screw is formed between the inner peripheral surface of the storage chamber and the outer peripheral surface of the tip of the plunger. Through the gap that is to be introduced into the storage chamber, the molten resin material to be introduced into the storage chamber, immediately before storage in the storage chamber, in such a gap,
Without being subjected to any shearing action due to the rotation operation of the screw, it is heated at a uniform temperature only by external heating by the heating cylinder, so that the temperature of the molten resin material can be made uniform, so that the molten resin material is stored in the storage chamber. The unevenness of the molten state of the molten resin material can be more effectively eliminated.

According to one preferred embodiment of the injection device according to the present invention, the storage chamber is formed in the front part of the heating cylinder, and the diameter of the front part is reduced by the amount corresponding to the reduced diameter of the front part. The thickness of the tip of the heating cylinder is increased.

In the injection device having such a configuration, the strength of the heating cylinder with respect to the injection pressure is effective because the thickness of the tip portion of the heating cylinder to which the highest injection pressure is applied is thickened. Can be enhanced,
Thereby, the molten resin material stored in the storage chamber can be injected at a higher injection pressure, and the entire heating cylinder uses a conventional injection device having a constant thickness. If the same injection pressure is used, the thickness of the heating cylinder can be reduced while ensuring sufficient strength of the heating cylinder with respect to the injection pressure. It is possible to make it smaller than that of the conventional device.

Further, according to another advantageous aspect of the injection device according to the present invention, the resin material supplied into the heating cylinder includes an inner peripheral surface of a hollow portion of the screw and an outer peripheral surface of the plunger. A piston ring that prevents the screw from entering into the hollow portion of the screw from between is provided on the outer peripheral portion of the plunger. Thus, the plunger can always be smoothly moved relative to the screw, so that the injection of the molten resin material by the relative movement of the plunger with respect to the screw can always be stably performed.

Further, according to another preferred embodiment of the injection device according to the present invention, the inner tip surface of the heating cylinder forming a continuous surface with respect to the inner surface of the nozzle hole of the injection nozzle is directed toward the tip. While being configured with a tapered surface having a small diameter, the distal end surface of the plunger projecting from the distal end of the screw is configured to have a tapered surface with a smaller taper angle than the inner distal end surface of the heating cylinder, Under a state in which the plunger protrudes from the screw tip, the tip face of the plunger and the inside tip face of the heating cylinder form a resin intrusion portion consisting of a fine gap between the respective tapered faces, It is configured to be abutted.

In the injection device having such a configuration, the molten resin material fed forward of the heating cylinder by the rotation operation of the screw is provided with a tapered surface at the tip surface of the plunger and an inner tip surface of the heating cylinder. The tapered surface portion of the plunger tip faces the rear of the heating cylinder due to the resin pressure of the molten resin material that has penetrated into the resin entry portion formed between the heating cylinder and the resin entry portion. And the plunger is moved backward. Therefore, in such an injection device, unlike the conventional device, the molten resin exerting a resin pressure for retreating the plunger between the distal end surface of the plunger and the inner distal end surface of the heating cylinder during forward movement of the plunger. It is not necessary to provide any moving mechanism for forcibly moving the plunger backward in order to form a space that allows the intrusion of the material, whereby the structure of the entire injection device can be advantageously simplified.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, in order to clarify the present invention more specifically, the configuration of an injection device according to the present invention will be described in detail with reference to the drawings.

First, FIG. 1 schematically shows an example of an injection apparatus having a structure according to the present invention in a state before an injection operation is started. As is apparent from FIG. 1, the injection device 10 includes a heating cylinder 12, a screw 14, and a plunger 16.

More specifically, the heating cylinder 12 constituting the injection device 10 has a substantially cylindrical shape having a predetermined length, and a raw resin is accommodated in an intermediate portion in the length direction. A hopper 18 is provided for supplying the air into the hollow portion of the heating cylinder 12. The heating cylinder 12
An injection nozzle 20 is provided at the front end of the front side (the left side in FIG. 1).
Are formed integrally, while two hydraulic cylinders 22 and 24 are provided at an end on the rear side (the right side in FIG. 1). In the heating cylinder 12, a plurality of band heaters 26 are provided on the outer peripheral surface of the portion where the hopper 18 is provided and the injection nozzle 20 is formed. A portion in front of the intermediate portion is heated by the plurality of band heaters 26.

The screw 14 is connected to the heating cylinder 12
It has a hollow substantially cylindrical shape having a shorter length and an outer diameter slightly smaller than its inner diameter, and a screw groove is formed on the outer circumferential surface on one side in the length direction, while the outer circumference on the other side is formed. The surface is a flat cylindrical surface. In the screw 14, an outward flange portion 28 is integrally provided on the other end outer peripheral surface which is a flat cylindrical surface, and the screw 14 is attached to the outward flange portion 28. A screw support plate 29 that is rotatably and relatively immovably supported is attached. Further, in the screw 14, the other end of the hollow portion is a large diameter portion which is larger in diameter by one circumference than the opposite side. A plurality of groove-shaped outer splines 30 are formed on the peripheral surface so as to extend continuously in the axial direction toward the other end. Further, in the large diameter portion of the hollow portion of the screw 14, a step surface to be stepped with the small diameter portion is a screw side engagement surface 32 having a tapered surface shape.

On the other hand, the plunger 16 has a solid cylindrical rod shape having a length longer than the screw 14 and an outer diameter slightly smaller than its inner diameter. A circumferential groove is formed at one end of the plunger 16 in the longitudinal direction, and a piston ring 34 made of a metal ring and having a known structure is externally fixed to the circumferential groove. ing. In this plunger 16,
A plurality of inner splines 36 having a ridge shape capable of being fitted to a plurality of outer splines 30 provided on the screw 14 are provided on the outer peripheral surface of the other end in the longitudinal direction. The plurality of inner splines 36 can be engaged with the screw-side engaging surface 32 of the screw 14 at the end faces of the plurality of inner splines 36 on the side where the piston ring 34 is formed. A plunger-side engaging surface 38 having a tapered surface is formed. Also,
A plunger support plate 4 that supports the plunger 16 so as to be rotatable about its axis and relatively immovable is provided at the tip of the plunger 16 on the side opposite to the side where the piston ring 34 is formed.
0 is attached. A motor 42 is fixed to the plunger support plate 40, and a rotating shaft (not shown) of the motor 42 is integrally rotatably connected to a tip of the plunger 16 on the side where the plunger support plate 40 is mounted. ing. Thus, the plunger 16 is rotated around the axis with the rotation of the motor 42.

In the injection device 10 according to the present embodiment, the heating cylinder 12 having the above-described structure
The screw 14 is rotatably mounted on the heating cylinder 12
The screw 14 is inserted so as to be relatively movable in the axial direction, and when the screw 14 is inserted into the heating cylinder 12, the plunger 16 is rotatable around the axis in the hollow portion of the screw 14. In addition, the screw 14 can be relatively moved in the axial direction with respect to the screw 14, and is inserted so as to protrude from the tip of the screw 14.

In the screw 14 inserted into the heating cylinder 12, the outer peripheral surface on the screw groove forming side has
While the plurality of band heaters 26 are positioned in front of the heating cylinder 12 in which the plurality of band heaters 26 are disposed, the formation portion of the outward flange portion 28 is positioned so as to protrude from the rear opening of the heating cylinder 12. The screw support plate 29 attached to the outward flange portion 28
Is connected to the piston rod 44 of the hydraulic cylinder 22 provided at the rear end of the heating cylinder 12.

On the other hand, in the plunger 16 inserted into the hollow portion of the screw 14, the plurality of inner splines 36 make the respective plunger-side engaging surfaces 38 face the screw-side engaging surfaces 32 of the screw 14. In addition, the screw 14 is slidably fitted to each of the plurality of outer splines 30, and the end of the screw 14 connected to the motor 42 protrudes from the opening of the screw 14 on the side where the outward flange portion 28 is formed. Further, a plunger support plate 40 attached to an end on the side connected to the motor 42 is connected to a piston rod 46 of the hydraulic cylinder 24 provided at a rear end of the heating cylinder 12. A piston ring 34 externally fixed to the end of the plunger 16 opposite to the end of the plunger 16 connected to the motor 42 has an outer peripheral surface in liquid-tight contact with the inner peripheral surface of the screw 14. Have been.

Thus, in the injection device 10, the plurality of inner splines 36 of the plunger 16 and the plurality of outer splines 30 of the screw 14 are connected with the rotation of the plunger 16 around the axis by the rotation of the motor 42. Are engaged with each other in the rotation direction of the plunger 16, whereby the screw 14 is integrally rotated in the same direction as the plunger 16. Further, the piston rod 44 attached to the screw support plate 29 is protruded and retracted, so that the screw 14 is moved forward and backward within the heating cylinder 12 by an amount corresponding to the operation amount of the piston rod 44. And a piston rod 46 attached to the plunger support plate 40.
Is protruded and retracted, the plunger 16 is screwed by the plurality of inner splines 36 into the screw 14.
While being guided by the plurality of outer splines 30, the piston rod 46 is relatively moved with respect to the screw 14 by an amount corresponding to the operation amount of the piston rod 46, so that it can be moved forward and backward within the heating cylinder 12. .

Here, the forward movement of the screw 14 in the heating cylinder 12 is caused by the forward movement of the screw 14 to the rear end face 49 of a thick portion 48 provided at the tip end of the heating cylinder 12 and described later. While the forward movement of the plunger 16 in the heating cylinder 12 is controlled by the contact of the distal end surface 51, the heating cylinder 1 forms a continuous surface with respect to the inner surface of the nozzle hole of the injection nozzle 20.
2 into the tapered inner end surface 21 of the plunger 16
(See FIG. 2). When the screw 14 and the plunger 16 are positioned at such a forward movement restricting position, the screw-side engaging surface 32 of the screw 14 and the plunger-side engaging surface 38 of the plunger 16 are arranged.
Are opposed to each other with a small gap therebetween, and when the screw 14 is moved backward in the heating cylinder 12 from the position for restricting the forward movement, the screw-side engaging surfaces 32 And the plunger-side engaging surface 38 are engaged with each other, and the plunger-side engaging surface 38 is pressed by the screw-side engaging surface 32, so that the plunger 16 moves in the heating cylinder 12 through the screw 14.
(See FIG. 3).

By the way, in the injection apparatus 10 of the present embodiment having the above-described structure, particularly, as shown in FIG.
Is formed into a thick portion 48 which is thickened inward by increasing the thickness thereof. The inner diameter of the thick portion 48 is smaller than the outer diameter of the screw 14 and the tip of the plunger 16 It is made larger than the outer diameter of the part. As a result, the storage chamber 50 in which the front end of the heating cylinder 12 is surrounded by the inner peripheral surface of the thick part 48 and the tip of the plunger 16 can be inserted, but the screw 14 cannot be entered.
Is formed.

In the storage chamber 50, since the inner diameter of the thick portion 48 that provides the storage chamber 50 is larger than the outer diameter of the distal end of the plunger 16, the distal end of the plunger 16 is connected to the storage chamber 50. When the plunger 16 is inserted into the inside of the plunger 16, the plunger 16 has an annular shape between the outer peripheral surface of the distal end of the plunger 16 and the inner peripheral surface of the thick portion 48 constituting the storage chamber 50.
6, a gap 52 having a narrow width corresponding to the difference between the outer diameter of the tip end and the inner diameter of the thick portion 48 is formed. Further, since the inner diameter of the thick portion 48 is smaller than the outer diameter of the screw 14, the screw 14 can be moved forward in the heating cylinder 12 with the retracting operation of the piston rod 44 of the hydraulic cylinder 22. As described above, when the front end face 51 of the screw 14 is brought into contact with the rear end face 49 of the thick portion 48, the space in the heating cylinder 12 where the screw 14 is arranged and the storage chamber 50 are separated. , So as to be partitioned in a liquid-tight manner.

As described above, the forward movement of the plunger 16 in the heating cylinder 12 is restricted by the contact of the front end surface 23 of the plunger 16 with the tapered inner end surface 21 of the heating cylinder 12. Has become
Here, the front end face 23 of the plunger 16 is
5 and the rear portion 27 have a stepped tapered surface shape having different taper angles, and the front portion 25
The rear portion 27 is formed with a taper angle smaller than that of the inner front end surface 21 while having a taper angle corresponding to the tapered inner front end surface 21.
Thus, when the front end face 23 of the plunger 16 abuts against the inner front end face 21 of the heating cylinder 12, the front end 25 of the front end face 23 comes into contact with the inner front end face 21 while the front end face 21 is in contact with the inner front end face 21. 23 and the inner tip surface 21
Between them, a resin intrusion portion 31 composed of a minute gap is formed.

Thus, when molding a resin molded article using the injection device 10 of the present embodiment having such a structure, the operation proceeds as follows, for example. .

That is, first, the screw 14 and the plunger 16 are moved forward in a state where the screw 14 and the plunger 16 are arranged in the forward movement restricting position as shown in FIG. As described above, the hydraulic pressure acting on the hydraulic cylinders 22 and 24 is reduced to a predetermined size, and the resin material serving as the raw material of the target resin molded product is heated via the hopper 18 to the heating cylinder 1.
Feed into 2. On the other hand, by rotating the motor 42 connected to the plunger 16 to rotate the plunger 16 and the screw 14 integrally, the resin material supplied into the heating cylinder 12 as shown in FIG. Is plasticized and melted by the external heating by the plurality of band heaters 26 and the shearing action of the resin material caused by the rotation of the screw 14 while being sent forward of the heating cylinder 12 by the rotation operation of the screw 14.

At this time, when the molten resin material first supplied into the heating cylinder 12 reaches the tip of the screw 14, the screw pressure of the molten resin material causes the screw 1 to move.
4 until the front end face 51 is pressed rearward and the resin pressure and the back pressure on the screw 14 are in an equilibrium state.
The screw 14 is moved backward, so that the front end face 51 of the screw 14 and the rear end face 49 of the thick part 48 of the heating cylinder 12 are located at the front end of the screw 14 in the heating cylinder 12. , A minute resin passage 54 is formed. In addition, this screw 1
4, the plunger 16 is pressed backward by the screw-side engaging surface 32 while the plunger-side engaging surface 38 is engaged with the screw-side engaging surface 32, and the plunger 16 moves backward. Therefore, the plunger 16 is located at the front of the storage chamber 50 near the injection nozzle 20.
A small space 56 is formed between the front end surface 23 of the heating cylinder 12 and the inner end surface 21 of the heating cylinder 12. And
When the resin passage 54 and the minute space 56 are formed,
The molten resin material first supplied into the heating cylinder 12 passes through the resin passage 54, into the gap 52 formed between the outer peripheral surface of the plunger 16 and the inner peripheral surface of the thick portion 50 in the storage chamber 50. To fill the gap 52, pass through the gap 52, and are introduced into the minute space 56 at the front of the storage chamber 50 and stored.

In this case, the rear part 27 of the front end face 23 of the plunger 16 and the inner end face 2
1, a resin intrusion portion 31 formed of a minute gap is formed, so that the retreating movement of the plunger accompanying the retreating movement of the screw 14 due to the resin pressure of the thermoplastic resin material is prevented. Even if it is not performed for some reason, the molten resin material introduced into the storage chamber 50 through the resin passage 54 formed by the backward movement of the screw 14 Of the plunger 16 due to the resin pressure of the molten resin material that has entered the resin intruding portion 31.
The rear portion 27 is pressed toward the rear of the heating cylinder 12 to cause the plunger 16 to move backward, whereby the plunger 16 is stored in the front portion of the storage chamber 50. Also,
As described above, the storage chamber 5 passes through the resin passage 54.
When the molten resin material is introduced into the plunger 16, the molten resin material is applied to the outer peripheral surface of the plunger 16 and the inner peripheral surface of the screw 14 by the piston ring 34 extrapolated at the tip of the plunger 16. Intrusion into the hollow portion of the screw 14 from between is prevented, and all of the molten resin material passing through the resin passage 54 is stored in the storage chamber 50.

Subsequently, as shown in FIG. 3, the plunger 16 and the screw 14 are further rotated integrally while the raw resin material is supplied from the hopper 18 into the heating cylinder 12, and the resin material is fed forward. , Plasticization,
Melts. Then, the molten resin material sent to the front of the heating cylinder 12 is sequentially passed through the resin passage 54 through the gap 5.
2 and then into the storage chamber 50. At that time, the molten resin material guided first into the gap 52 of the storage chamber 50 is sent further forward so as to be pushed forward by the molten resin material guided later. The molten resin material introduced into the inside is sequentially accumulated rearward with respect to the previously introduced molten resin material. Further, at this time, the molten resin material introduced later into the storage chamber 50 and accumulated behind the previously introduced molten resin material is the tip end surface of the plunger 16 which is positioned to enter the storage chamber 50. To be stored above, such a plunger 16
By the resin pressure of the molten resin material introduced later,
As a result, the molten resin material is gradually stored in the storage chamber 50 while the plunger 16 is moved backward.

Subsequently, as shown in FIGS. 4 and 5, the integral rotation of the plunger 16 and the screw 14 is continuously operated until the storage chamber 50 is filled with a predetermined amount of the molten resin material. The storage chamber 50
It is introduced one after another and stored. And the storage chamber 5
0 is filled with a predetermined amount of molten resin material.
Is stopped, and the integral rotation of the plunger 16 and the screw 14 is stopped.

Thereafter, as shown in FIG. 5, the piston rod 44 of the hydraulic cylinder 22 is retracted and operated, and the screw 14 is moved forward to a position where its front end face 51 contacts the rear end face 49 of the thick portion 48. By letting
The resin passage 54 is closed, so that the space in which the screw 14 is disposed in the heating cylinder 12 and the storage chamber 50 are liquid-tightly partitioned. At this time, the piston rod 46 of the hydraulic cylinder 24 is caused to protrude so that the molten resin material in the resin passage 54 can enter the storage chamber 50, and the plunger 16 is moved backward by a predetermined amount.

Then, the piston rod 46 of the hydraulic cylinder 24 is retracted to operate the plunger 1.
The molten resin material 6 stored in the storage chamber 50 is injected into a molding cavity of a molding die (not shown). Then, the molten resin material is solidified in the molding cavity, thereby obtaining a desired resin molded product.

As described above, in the injection device 10 of this embodiment, unlike a general in-line screw type injection device, the plunger 1
6 is moved backward, and the screw 14 does not move backward at all, so that the wear of the screw 14 can be suppressed. Further, the relative positional relationship between the heating zone by the band heater 26 of the heating cylinder 12 and the screw 14, and the screw 14 1
Since the effective length of No. 4 does not significantly change, the occurrence of unevenness in the molten state of the molten resin material can be effectively prevented.

In the injection device 10,
The molten resin material plasticized and melted by the integral rotation of the screw 14 and the plunger 16 and first sent forward is formed in the resin passage 52 by heating with the front end face 23 of the plunger 16. Inner tip surface 2 of cylinder 12
1 and is stored in a front portion near the injection nozzle 20 in the storage chamber 50 while being sent forward and introduced into the storage chamber 50. The molten resin material to be introduced is accumulated in a rearward order with respect to the previously introduced molten resin material, and the molten resin material to be introduced last is the tip end surface of the plunger located at the rearmost part of the storage chamber. Since the resin material is stored on the surface 23, it is possible to reliably perform first-in first-out operation by first heating, plasticizing, and injecting the molten resin material first.

In addition, in such an injection device 10,
After the injection operation, even if the molten resin material remains on the distal end surface 23 of the plunger due to adhesion or the like, such a residual molten resin material has a short heat history lastly introduced into the storage chamber 50. Yes, and screw 14 after injection operation
With the restart of the integral rotation operation of the plunger 16 and the
The molten resin material newly introduced into the storage chamber 50 is moved to the vicinity of the injection nozzle and is injected in the next injection operation, so that the molten resin material is excessively heated in the storage chamber 50 for a long time. The deteriorated and carbonized resin material is not ejected from the storage chamber 50, and is not deteriorated or carbonized. It can be effectively avoided that the article is molded.

Therefore, when the injection device 10 according to the present embodiment is used, the first-in first-out of the molten resin material is reliably performed while effectively preventing the abrasion of the screw 14 and the unevenness of the molten state of the molten resin material. Therefore, a resin molded article of excellent quality without product defects can be molded very advantageously.

In the injection device 10, the molten resin material plasticized and melted by the integral rotation of the plunger 16 and the screw 14 is supplied to the heating cylinder 12.
Is stored in the storage chamber 50 from a portion which can be passed through a narrow gap 52 formed between the inner peripheral surface of the thick portion 48 and the outer peripheral surface of the distal end portion of the plunger 16. Immediately before the molten resin material, the screw 14
Without the shearing action of the rotating action of the
8, the molten resin material can be heated at a uniform temperature only by external heating by the band heater 26 disposed on the outer peripheral portion, so that the temperature of the molten resin material can be made uniform. The occurrence of unevenness in the molten state of the molten resin material to be performed can be more effectively eliminated.

Further, in the injection device 10 of the present embodiment, the heating cylinder 1
The highest injection pressure is applied since the portion surrounded by the inner peripheral surface of the thick portion 48 whose front end portion is thickened is a storage chamber 50 for storing the molten resin material. The wall of the storage chamber 50 is thickened, whereby the strength of the entire heating cylinder 12 with respect to the injection pressure can be effectively increased. And as a result, it becomes possible to inject the molten resin material stored in the storage chamber 50 at a higher injection pressure, and when employing the same injection pressure as when using the conventional apparatus,
The thickness of the heating cylinder 12 can be reduced while the strength of the entire heating cylinder 12 with respect to the injection pressure is sufficiently secured, so that the outer diameter of the heating cylinder 12 is advantageously reduced to be smaller than that of the conventional apparatus. You can do it.

In the injection device 10, the outer peripheral surface of the plunger 16 and the inner peripheral surface of the screw 14 are formed by the piston ring 34 inserted at the tip of the plunger 16 inserted into the hollow portion of the screw 14. The molten resin material is prevented from entering the hollow portion of the screw 14 from between the surface and the surface, and all of the molten resin material is
From the position where the plunger 16 is guided into the gap 52, it is possible to effectively prevent the forward and backward movement of the plunger 16 from being hindered by the molten resin material that has entered the hollow portion of the screw 14. Thus, the operation of injecting the resin material by the forward movement of the plunger can always be performed stably.

Further, in such an injection device 10,
Since a resin intrusion portion 31 composed of a minute gap is formed between the rear portion 27 of the front end surface 23 of the plunger 16 and the inner front end surface 21 of the heating cylinder 12, the screw 14 is pressed by the resin pressure of the molten resin material. Even if the retreat movement of the plunger accompanying the retreat movement may not be performed for some reason, the plunger 16 is caused to retreat by the resin pressure of the molten resin material that has entered the resin intruding portion 31 and melted. From the place where the resin material is stored in the front part of the storage chamber 50, between the front end face 23 of the plunger 16 and the inner front end face 21 of the heating cylinder 12 while the plunger 16 is moving forward. In order to form the minute space 56 which allows the intrusion of the molten resin material which exerts the resin pressure for moving the plunger 16 backward, the screw 14 is formed. During backward movement, necessarily, it is not necessary to engage the plunger-side engaging surface 38 of the plunger 16 in the screw-side engaging surface 32 of the screw 14. Therefore,
In such an injection device 10, unlike a conventional device,
Under the state of engagement between the plunger-side engaging surface 38 and the screw-side engaging surface 32, the distal end of the plunger 16 protruding from the screw 14 is attached to the inner distal end surface 21 of the heating cylinder 12 at its front end surface 23. There is no need to employ any structure that requires high dimensional accuracy, such as contact, so that the advantage is obtained that the structure is simplified.

In the injection device 10, the plunger 16 is moved forward to move the storage chamber 5.
After the molten resin material in the cylinder 0 is injected into the molding die, the front end face 23 of the plunger 16 is brought into contact with the inner front end face 21 of the heating cylinder 12 at the front part 25 thereof. After such an injection operation, the storage chamber 5 is removed from the injection mold of the molten resin material.
Backflow into zero can be prevented, so that an injection molding method in which the injected molten resin material is further pressed in the molding die can be carried out very advantageously.

The embodiment of the present invention has been described in detail above, but this is merely an example.
The present invention is not construed as being limited to the embodiments.

For example, in the above embodiment, the plunger 1
6 is connected to the motor 42 and is engaged with the screw 14 so as to be integrally rotatable. The screw 14 is rotated as the plunger 16 is rotated by the rotational drive of the motor 42. However, it is also possible to connect the motor 42 to the screw 14 and directly rotate the screw 14 by rotating the motor 42. In this case, of course, the plunger 16 may be integrally rotated with the screw 14 or the plunger 16 and the screw 14
May be configured to be relatively rotatable, and only the screw 14 may be rotated.

Further, the structure for moving the screw 14 and the plunger 16 forward and backward is not limited to the one shown in the above-described embodiment, but can be relatively moved. Any structure that can be moved forward and backward in the inside can be adopted. For example, a hydraulic mechanism for moving the screw 14 and the plunger 16 forward and backward may be provided separately from the heating cylinder 12.

Further, in the above-described embodiment, the inner end of the heating cylinder 12 is formed so that the front end thereof has an inner diameter smaller than the inner diameter of the screw 14 and the outer diameter of the plunger 16 at the front end. The storage chamber 50 is formed in a portion surrounded by the inner peripheral surface of the thick part 48, and the storage chamber 50 is The inner diameter of the plunger 16 is set to be smaller than the inner diameter of the screw 14 in the heating cylinder 12 so that the plunger 16 projects from the tip of the screw 14 and projects into the storage chamber 50. What is necessary is just to be comprised so that a micro clearance may be formed between the inner peripheral surfaces of the storage chamber 50. Therefore, by reducing the outer diameter of the front end portion of the heating cylinder 12 without increasing the thickness at all, the inner diameter of such a portion is made smaller than the inner diameter of the portion where the screw 14 is disposed, and the storage chamber It is also possible to form 50.

Further, in the above embodiment, the screw 1
When the molten resin material plasticized and melted by the rotation operation of 4 and sent forward reaches the distal end portion of the position where the screw 14 is disposed, the resin passage 52 is formed at the distal end portion, At the front of the storage chamber 50, a minute space 5
6 are formed, but this minute space 56 is formed.
Is not always necessary. However, as described above, in the above-described embodiment, the front end surface 23 of the plunger 16 and the inner front end surface 21 of the heating cylinder 12 have a special abutment structure, and the melt introduced into the front part in the storage chamber 50 This is because the plunger 16 is caused to retreat by the resin pressure of the resin material. Even if such a minute space 56 is provided,
Screw 14 and plunger 1 due to increase in molten resin material
6 instead of being formed by an integral retreat
The plunger 16 may be formed in advance in a state where the plunger 16 is located at the forward movement restricting position. In this case, of course, the plunger 16 does not abut the front end face 23 against the inner front end face 21 of the heating cylinder 12 at the forward movement restriction position.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, various changes, modifications, improvements, and the like can be made, and any of such embodiments can be implemented in the present invention without departing from the spirit of the present invention. It is to be understood that they are included within the scope of the invention.

[0053]

As is clear from the above description, in the injection device according to the present invention, the plunger is provided in the hollow portion of the hollow cylindrical screw rotatably disposed in the heating cylinder. In contrast to this, it is possible to reliably perform first-in first-out while effectively securing the many advantages obtained by having a structure that is inserted so as to be relatively movable in the axial direction. It is possible to mold a resin molded article of excellent quality without any problem very advantageously.

[Brief description of the drawings]

FIG. 1 is an explanatory longitudinal sectional view showing an example of an injection device according to the present invention.

FIG. 2 is a partially enlarged explanatory view of FIG.

FIG. 3 is an explanatory view showing an example of a step of molding a resin molded product by using the injection device shown in FIG. 1, wherein plasticization is performed while feeding a resin material supplied into a heating cylinder forward; Shows the state of melting.

FIG. 4 is an explanatory view showing another example of a step of molding a resin molded product using the injection device shown in FIG. 1, wherein a plasticized and molten molten resin material is stored in a storage chamber. Shows the status of

FIG. 5 is an explanatory view showing another example of the step of molding a resin molded product using the injection device shown in FIG. 1, showing a state in which a storage chamber is filled with a molten resin material.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Injection apparatus 12 Heating cylinder 14 Screw 16 Plunger 20 Injection nozzle 26 Band heater 31 Resin intrusion part 42 Motor 48 Thick part 50 Storage chamber 52 Gap 54 Resin passage 56 Micro space

Claims (4)

[Claims] 1. A hollow cylindrical screw is rotatably disposed in a heating cylinder having an injection nozzle at a tip thereof and relatively movable with respect to the heating cylinder, and a plunger is provided in a hollow portion of the screw. Is provided so as to be relatively movable in the axial direction with respect to the screw, and is provided so as to be able to protrude from the tip of the screw. The resin material supplied into the heating cylinder is rotated by the rotation of the screw. While being plasticized and melted while being sent forward, the molten resin material is stored in the front part in the heating cylinder, and the stored molten resin material is injected from the injection nozzle by the relative movement of the plunger with respect to the screw. In the injection device, the inside diameter of the heating cylinder at the front portion is smaller than the inside diameter of the heating cylinder at the screw disposition portion. The storage chamber is provided with a size such that the distal end of the plunger can enter the storage chamber by a relative movement with respect to the screw while forming a gap between the plunger and the inner peripheral surface of the storage chamber. When the screw is in the intruded state, the molten resin material sent forward of the heating cylinder by the rotation operation of the screw causes the first resin between the outer peripheral surface of the plunger tip and the inner peripheral surface of the storage chamber to move. An injection device configured to be introduced into and stored in the storage chamber through a gap of the injection chamber. 2. The heating chamber is formed at a front portion in the heating cylinder, and the thickness of the front end portion of the heating cylinder is increased by an amount corresponding to the reduced diameter of the front portion. 3. The injection device according to claim 1. 3. A piston ring for preventing a resin material supplied into the heating cylinder from entering the hollow portion of the screw from between the inner peripheral surface of the hollow portion of the screw and the outer peripheral surface of the plunger, 3. The injection device according to claim 1, wherein the injection device is provided on an outer peripheral portion of the plunger. 4. An inner front end surface of the heating cylinder, which forms a continuous surface with respect to an inner surface of a nozzle hole of the injection nozzle, is configured to have a tapered surface whose diameter becomes smaller toward the front end. The distal end surface of the plunger projecting from the distal end has a taper surface having a smaller taper angle than the inner distal end surface of the heating cylinder, and when the plunger projects from the screw distal end, the distal end of the plunger The surface and the inner front end surface of the heating cylinder are configured to be brought into contact with each other while forming a resin intrusion portion formed of a minute gap between the respective tapered surfaces. The injection device according to any one of the above.