JPH0976308A - Injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an operating oil and a resin material from mixing with each other by providing a second rotation drive means for a second screw in a second cylinder, a movement drive means for moving a first screw in the axial direction and a first rotation drive means for rotation at the back end part of the first screw passing through the second screw. SOLUTION: A first cylinder 2 for housing a first screw 4 and a second cylinder 3 for housing a second screw 10 are provided. The first screw 4 is arranged in a through hole 25 of the second screw 10. The second screw 10 is driven by a second screw drive motor 28 through a large-diameter gear 26 in a drive chamber 22 at the back end of the second cylinder 3 and a pinion 27. At a terminal end, a cross roller bearing 29 is provided. The back end of the first screw 4 is connected to a first screw drive motor 32 and a hydraulic cylinder 34 for moving the first screw 4 in the axial direction is provided. By backing, a resin material is retained at the head end, advanced by the hydraulic cylinder 34, and injected by a nozzle 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasticizing injection device for an injection molding machine, and more particularly to an injection molding machine having a large-capacity resin injection device adapted for a large molded product.

[0002]

2. Description of the Related Art Conventionally, when molding a large-sized resin molded product, a method of using one large injection unit is used, and a plurality of injection units are used from a plurality of nozzles for one resin molding die. An injection molding method, a method of injecting from a plurality of injection resin passages of a plurality of injection units to form an injection nozzle, or the like has been adopted.

However, the method of using a large injection unit is
There is a problem that the injection screw, the injection cylinder, etc. become large and heavy, and the screw disassembly and cleaning after the injection molding work and the reassembly work become large, which takes a lot of time and effort.
In addition, in the method of injection molding from a plurality of injection nozzles into one mold, the material resin forming the molded product is injected from each nozzle of the plurality of injection units to form the molded product. Since the boundary of the resin is generated in the product, a weak point in strength is likely to occur, an external defect is likely to occur, and a defective product is likely to occur. Further, in the method of using the injection nozzle in which the outlet resin passages of a plurality of injection units are combined into one, the thermal strain fatigue of the injection units must be taken into consideration, which complicates the structure and increases the apparatus cost. Not only that, but there is also the problem that maintenance costs such as cleaning will increase.

On the other hand, an invention "injection molding apparatus" having a double cylinder structure for the purpose of changing the kneading ability by varying the plasticizing amount for different resins of various materials is disclosed in Japanese Patent Laid-Open No. 5-24082. Have been proposed in. As shown in FIGS. 5 and 6, this device is considered to be one of those having a structure capable of molding a large-capacity molded product.
An outline of this will be described.

In FIG. 5, 01 is the first cylinder portion 02.
And a second cylinder portion 03, which are integrally formed cylinders, and the nozzle 02a is provided at the tip of the first cylinder portion 02.
It has a section. The first cylinder portion 02 has a smaller diameter than the second cylinder portion 03, and has a vent portion 0 on the outer peripheral surface.
2b is provided. Further, inside the first cylinder portion 02, the tip end portion of the first screw 4 provided with a screw on the outer peripheral surface, which is rotatable and axially movable, is accommodated.

At the rear end of the tip of the first screw 04,
The first screw extension shaft 04a formed integrally is provided in the second cylinder 03, and the second screw 01 described later is provided.
0, the planetary gear unit 05 that constitutes the second rotating means, and the piston 07 of the cylinder chamber 06, and extends rearward, and is integrally formed at the rear end of the first screw extension shaft 04a. The end portion 04b projects outward from the rear end 03b. The rear end portion 04 of the first screw extension shaft 04a
In b, a motor 08 forming a first rotating means is provided, and in order to move the first screw 04 in the axial direction,
The piston 07 driven by the first hydraulic oil moves the extension shaft 0 within the cylinder chamber 06 provided at the rear end of the second cylinder 03.
It is fixed to the rear of 4a.

A hopper 09, which communicates with the inside of the second cylinder portion 03, is provided on the outer peripheral surface of the second cylinder portion 03 having a diameter larger than that of the first cylinder portion 02. Further, in the second cylinder portion 03, a second screw 010 having a diameter larger than that of the first screw 04 and constituting one conventional screw together with the above-mentioned first screw 04 is provided. As described above, the first screw extension shaft 04a penetrates the through hole 10a in which the axial center portion of the second screw 010 is provided in the axial direction.

Further, at the tip of the second screw 010, as shown in FIG. 6, a conical tip taper wall 01 is formed.
0b is formed, and the tip tapered wall 010 and the second
Inner wall 03a formed on the inner peripheral surface of the tip portion of the cylinder portion 03
A throttle gap 011 is formed between and. Further, the rear end portion of the second screw 010 is connected to the second cylinder portion 3
Is an annular portion 10f having an outer peripheral surface that is in sliding contact with the inner peripheral surface of
A planetary gear device 05 is provided in a recess 010c formed on the inner peripheral side of the planetary gear device 05. The sun gear of the planetary gear device 05 is mounted on a first screw extension shaft 04a passing through the recess 010c via a key. It is fixed and is integrally rotatable.

Further, the annular portion 1 forming the recess 010c
The pressure means 020 for axially moving the second screw 010 is provided at 0f and its rear side.
This pressure means 020 causes the second hydraulic oil to form the first chamber 010 in which the second screw 010 is formed in the annular portion 10f.
d and the rear of the annular portion 10f are partitioned into cylinder chambers 06
A partition wall 03c provided in the second cylinder 03 for partitioning
Second chamber 01 formed by the rear end surface of the second screw 010
0e and the second screw 010 moves in the range of the clearance adjusting stroke 050, whereby the throttle clearance 011 can be made variable.

A case of operating the injection molding apparatus having this structure will be described. First, in the plasticizing step of the material resin, the material resin supplied from the hopper 09 to the inside of the second cylinder portion 03, that is, the outer peripheral surface of the second screw 010 is melted and kneaded by the rotation of the second screw 010, It is sent to the front side, passes through the throttle gap 011 and is sent to the outer periphery of the first screw 04 housed in the first cylinder part 02. During this plasticization, pressure oil is supplied to the second chamber 010e behind the second screw 010 by the pressure means 020, so that the second screw 010 passes through the axial center portion of the first screw extension shaft 04a. And guides the vehicle forward, and the throttle gap 011 becomes smaller.

By making the throttle clearance 011 small, the flow passage area of the material resin is narrowed, and the time that the material resin stays in the second cylinder portion 03 becomes longer, which allows the second screw 010 to increase more. It will be kneaded for the time. At the same time, the amount of material resin discharged from the second screw 010 to the first screw 04 side also decreases, and the plasticizing ability is changed by adjusting the throttle 011 gap. Therefore, one screw, that is, the second screw 010
The throttle clearance 01 by moving the
By changing 1, the kneading state and the plasticized state suitable for the type of material resin can be obtained, and the plasticizing ability can be changed.

As described above, the double cylinder structure injection molding apparatus proposed in Japanese Patent Laid-Open No. 5-24082 proposes an injection screw (first screw 04) and an injection cylinder (first screw) for molding a large molded product. (Cylinder), etc. does not need to be a large injection unit that becomes large and heavy, and it does not require much labor for screw disassembly and cleaning and reassembly work after work. Since it is not designed to inject the molten resin from the nozzle into the same mold, there is no weakness in strength due to the boundary of the resin in the molded product, and no defective product in appearance. .

Furthermore, since the outlet resin passages of a plurality of injection units are not combined to have an injection nozzle having a single injection outlet, the structure becomes complicated and the apparatus cost and the maintenance cost required for cleaning, etc. Does not grow. In addition, as described above, this injection molding apparatus can change the kneading ability and the plasticizing ability and stabilize the molding conditions without replacing the screw.

However, in this injection molding apparatus, as described above, the second cylinder 03 has the piston 0 inside.
7 also serves as a hydraulic cylinder for moving the first screw 04 in the axial direction, and the high pressure and the low pressure are repeatedly loaded by the molten resin in the first cylinder 02 by their operation. In response to this, the piston 07
The high pressure and the low pressure are repeatedly applied also to the hydraulic cylinder side (second chamber 10e) partitioned by the partition wall 03 in the front of the working compartment of No. 2, so that the second chamber 010e passes through the gap between the second cylinder 03 and the second screw 010. Hydraulic oil inside leaks to the material resin side,
In addition, there is a problem that the molten material resin or the hydraulic oil leaks and mixes from the gap between the reciprocating injection first screw 04 and the second screw 010.

[0015]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the conventional apparatus and remains in an injection molding apparatus having a double cylinder structure which is considered to be suitable for molding a molded product having a large capacity. The second hydraulic oil for driving the second (large diameter) screw 010 in the axial direction leaks to the material resin side inside the second cylinder 03 through the outer peripheral surface of the second screw 010, and also the second screw 010. First screw 04 passing through
Through the gap formed between the second screw 010, the second hydraulic oil, or the first hydraulic oil for axially driving the first screw 04, and the material resin in the first cylinder 02. It is an object of the present invention to provide an injection molding device capable of solving the problem that the above-mentioned components are mixed.

[0016]

Therefore, the injection molding machine according to the first aspect of the present invention has the following means. (1) The tip is provided with a nozzle part for injecting a material resin into a mold for forming a molded product from a high-pressure molten material resin, and the nozzle part penetrates the axial center part of the second screw to move back and forth and rotate. First
A small-diameter first cylinder portion that accommodates the front projection of the screw, and a step portion inside the tip portion that has a diameter larger than that of the first cylinder portion and that communicates with the rear end of the first cylinder portion have a conical shape.
A conical annular resin passage gap is formed between the conical shape formed at the tip of the second screw housed therein and is supplied to the outer peripheral surface of the second screw from a hopper provided on the outer peripheral surface. Injection including a double cylinder structure injection cylinder composed of a second cylinder part, which supplies the material resin to the outer peripheral surface of the protrusion of the first screw to the first cylinder part by the rotation of the second screw The following molding machines were used.

A. It is installed at the rear end of the second cylinder,
A thrust that is housed inside the second cylinder part and has a rear end portion of a second screw having a shaft center portion through which the first screw penetrates so that the rear end portion is freely rotatable and axial movement is restrained and supported. Bearings are provided.

B. Between the thrust bearing and the position where the material resin is supplied from the hopper on the outer peripheral surface of the second cylinder portion to the outer peripheral surface of the second screw, the drive is sealed by the inner peripheral surface of the second cylinder portion and the outer peripheral surface of the second screw. The chamber was provided with a second rotation drive means for rotating the second screw that sends the material resin supplied forward while kneading the supplied material resin.

C. It is provided at the rear end of the first screw, which penetrates the axial center of the second screw and projects rearward from the rear end of the second screw supported by the thrust bearing, and moves the first screw in the axial direction. A first rotation drive means for rotating the first screw is provided, and the first screw is rotated and retracted by the material resin supplied into the first cylinder portion through the gap by the second screw, and the first screw is rotated by a predetermined amount. After the material resin of (1) is stored in the storage section formed between the tip of the first screw and the nozzle section, the drive unit that pushes out from the nozzle section into the mold by operating the first rotation drive means and the moving means. Provided.

In the first screw, the second material resin supplied from the rear end of the second screw to the outer peripheral surface of the first screw is sent forward through the through hole of the second screw, It is also possible to mix and knead with the material resin supplied from the second screw through the gap at the portion protruding from the through hole, and supply the resin to the nozzle portion.

According to the injection molding machine of the present invention, the first means is provided at the resin inlet of the clamped mold of the injection molding machine by the above-mentioned means.
In a state where the nozzle portion of the cylinder is pressed and the material resin inside the first cylinder is heated, sufficiently kneaded and plasticized to satisfy the injection condition, (i) the second screw is the second rotation driving means. Driven slowly to rotate, the first screw retreats while rotating rapidly at a speed commensurate with the extrusion amount of the material resin extruded from the gap by the rotation of the second screw, and the molten material resin moves from the tip of the first screw. A fixed amount is stored in the front first cylinder.

(Ii) Next, the first screw is moved forward by the moving drive means of the drive unit for injection, and the material resin accumulated at the tip of the first screw is injected from the nozzle into the mold. At this time, the second screw slowly rotates by the second rotation drive means and the first screw by the first rotation drive means of the drive unit to hold the material resin pressure.

(Iii) After a certain period of time has elapsed, after solidifying the resin in the mold, the rotations of the second screw and the first screw are stopped, and the first screw is slightly retracted for suck back.

(Iv) Open the mold and take out the molded product,
The mold is clamped again, the process returns to the first step (1), and each step is repeated. The rotation speeds of the second screw and the first screw can be independently set according to the type of material resin and the plasticizing conditions. Further, since the screw diameter of the second screw can be made larger than that of the first screw,
A large amount of resin can be extruded and can be applied to large molded products.

Further, even if the pressure in the first cylinder portion becomes high, the first screw rotates so as to return the molten material resin to the tip end direction, so that the molten material resin is mixed between the first screw and the second screw. There is no risk of leaking out from the gap between the through parts.
Further, the second screw does not move in the axial direction, and since the hydraulic oil for moving the second screw in the axial direction is not used, the hydraulic oil is discharged from the gap between the second screw and the second cylinder. The problem that occurred in the conventional device such as leakage and mixing with the material resin does not occur, and the drive unit that operates the first screw penetrates the second screw and moves backward from the rear end of the second screw. Since it is provided at the rear end portion of the projected first screw, it is possible to prevent the hydraulic oil of the first screw from mixing with the material resin through the through hole of the second screw.

The injection molding machine according to the second aspect of the present invention has the following means in addition to the above-mentioned means (1). (2) a second rotation drive means for rotating the second screw,
It is composed of a gear fixed to the outer peripheral surface of the second screw penetrating the drive chamber, a pinion meshing with the gear, and a reduction motor having a pinion fixed to the output shaft.

As a result, in addition to the action and effect of the above (1), in the injection molding machine of the present invention, the second rotation drive means can be simply and compactly assembled. Further, the second rotation drive means controls the rotation of the second screw,
The first screw and the second screw can be driven completely independently without interfering with the rotation of the first screw or the movement in the axial direction, and the driving of the first screw and the second screw depending on the type of material resin and the plasticizing condition. It can be done arbitrarily. Thereby, it is possible to favorably supply the material resin from the throttle gap to the first screw or hold the resin pressure when the material resin is injected from the nozzle portion into the mold by the drive unit.

The injection molding machine according to a third aspect of the present invention has the following means in addition to the above-mentioned means (1) or the above-mentioned means (1) and (2). (3) The first screw having the drive unit at the rear end portion, the front end portion of which is housed in the first cylinder, penetrates the axial center portion of the second screw, and projects rearward from the rear end of the second cylinder, I assumed that.

A. The partial internal screw formed continuously from the spiral screw formed on the outer peripheral surface of the tip portion housed in the first cylinder is attached to the outer peripheral surface of the tip portion of the penetrating portion of the first screw penetrating the second screw. ~ 3 rolls were provided.

B. The external shape is made cylindrical from the rear end of the internal screw formed in the penetrating portion, penetrates the second screw, projects rearward from the rear end of the second cylinder, and drives the front end provided with the screw. A cylindrical shaft was provided to connect to the unit.

As a result, the above (1) or (1),
In addition to the function and effect of (2), in the injection molding machine of the present invention, the pressure of the material resin extruded from the nozzle portion can be increased and the holding pressure of the material resin extruded from the nozzle portion can be increased. Further, the amount of the material resin injected from the first screw into the mold is increased by the volume of the internal screw portion provided in the through hole of the second screw, so that a larger molded product can be manufactured.

Further, the material resin injected from the gap can surely retract the first screw at a speed commensurate with the amount of extrusion, and the section for storing the molten material resin at the tip of the first screw is further improved. It can be reliably formed,
It is possible to sufficiently knead the injected material resin with the first screw. Also, by providing a cylindrical shaft,
The rigidity of the first screw can be increased, and a large driving force can be transmitted from the drive unit to the tip of the first screw where a large load is generated.

The injection molding machine according to a fourth aspect of the present invention has the following means in addition to the above-mentioned means (1) or the above-mentioned means (1) and (2). (4) The helical screw formed on the outer peripheral surface of the first screw in the portion housed in the first cylinder is continuously connected to the entire outer peripheral surface of the first screw in the portion penetrating the second screw. An internal screw was installed.

Further, between the thrust bearing provided at the rear end of the second cylinder and the drive unit provided at the rear end of the first screw, projecting rearward from the rear end of the second cylinder, the outer circumference is The first screw, which is provided with an all-internal screw on its surface, penetrates the thrust bearing that restrains axial movement and rotatably supports, and projects rearward from the rear end of the second cylinder. A bearing that supports the rear end of the two screws, and a material resin that is provided on the outer peripheral surface and that is different from the material resin that is supplied from the hopper to the second screw to all the internal screws of the first screw. A bearing stand provided with two hoppers was provided. Note that the different material resin does not necessarily refer to a different material resin.

As a result, in addition to the action and effect of the above (1) or (1) and (2), in the case of the injection molding machine of the present invention, the material resin stored at the tip of the first screw during injection. Since the amount is the amount of material resin added to the amount of material resin delivered from the first screw and the amount of material resin delivered from the second screw, a larger amount of material resin can be injected from the nozzle portion into the mold, Large molded products can be manufactured. Further, without using a plurality of injection units, it is possible to knead and plasticize two kinds of material resins under different conditions to make a molded product of the mixed material resin.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an injection molding machine of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing a first embodiment of an injection molding machine of the present invention, and FIG. 2 shows the second cylinder portion of the embodiment shown in FIG. 1, the first screw, and the periphery of a drive mechanism for the second screw. It is an overhead view. Further, as understood from the figure, this injection molding machine has a structure in which an injection molding unit and a screw extrusion device are combined.

As shown in the figure, a unit base 16 is attached to the molding apparatus main body 15. The unit base 16 can be moved in the screw axis direction of the injection molding unit by a rail guide laid on the molding apparatus body 15, and is reciprocated by a hydraulic cylinder 17. The injection cylinder 1 is fixed to the unit base 16 at its base portion 18. By driving the hydraulic cylinder 17,
When the unit table 16 on which the injection cylinder 1 is placed advances toward a mold plate (not shown) provided on the left side of the drawing, the nozzle portion 2a provided at the tip of the injection cylinder 1 and injecting the material resin is Touch the nozzle to the resin injection port of the mold for molding the resin.

The injection cylinder 1 has a heater 19 wound around its outer peripheral surface and is larger than the first cylinder portion 2 for accommodating the first screw 4 and the second cylinder 10 for accommodating the second screw 10. It has a double cylinder structure including a second cylinder portion 3 having a diameter. Further, a step portion inside the injection cylinder 1 of a portion where the first cylinder portion 2 and the second cylinder portion 3 communicate with each other has a conical shape, and is between the conical shape formed at the tip of the second screw 10. A conical annular gap 11 that forms a passage for the material resin is formed therein. The second cylinder 3, which is the large diameter portion of the injection cylinder 1, is provided with a resin injection hole 21 in the radial direction, and on the outer peripheral surface of the second cylinder 3 where the resin injection port 21 is opened, The hopper 9 is attached.

A large-diameter drive chamber 22 is integrally provided at the rear end portion of the second cylinder 3 behind the mounting portion of the hopper 9,
A lid 23 for opening the rear of the drive chamber 22 is attached to this. The extrusion screw 24 is processed on the outer peripheral surface,
The second screw 10 rotatably accommodated in the second cylinder portion 3 is provided with a shaft concentric through hole 25, through which the first screw 4 is rotatable and axially movable. Penetrates. The rear portion of the second screw 10 projects into the drive chamber 22 at the rear end portion of the second cylinder portion 3, and the large diameter gear 26 is fixed to this portion. In the central portion of the lid 26, there is a cross roller bearing 29 as a thrust bearing.
Through the, the direction of rotation is freely supported and the movement is restrained in the axial direction to be supported.

The pinion 27 meshing with the large diameter gear 26 is
It is attached to the output shaft of a second screw drive motor 28, which is a deceleration motor fixed to the unit base 16. The large-diameter gear 26, the pinion 27, and the second screw drive motor 28 constitute second rotation drive means for rotating the second screw 10.

The tip of the first screw 4 is housed in the first cylinder portion 2 which is a small diameter portion of the injection cylinder, and the central portion thereof has a through hole 25 provided in the axial center portion of the second screw 10 as described above. The partial internal screw 31 continuously attached to the extruding screw 30 provided on the outer peripheral surface of the tip end portion of
The winding is provided inside the tip of the through hole 25 of the second screw 10.

The rear side of the rear end of the partial internal screw 31 is formed in the cylindrical shaft 20 that loosely fits into the through hole 25 of the second screw 10, and the through hole 25 of the second screw 10 is formed.
The rear end portion of the first screw 4, which projects further rearward, is connected to the output shaft of the first screw drive motor 32 as the first rotation drive means for rotating the first screw 4. Further, a bracket 33 having a central portion pivotally attached is attached to the rear end of the first screw 4, and both ends of the bracket 33 are moved and driven to move the first screw 4 in the axial direction. Is provided as a hydraulic cylinder 34. A drive unit 35 is constituted by the hydraulic cylinder 34 including the first screw drive motor 32 and the bracket 33.

Next, the operation of the injection molding machine of this embodiment will be described. The nozzle portion 2a of the first cylinder portion 2 is pressed against the resin inlet of the clamped mold of the injection molding machine,
The material resin charged into the hopper 9 is heated while being sent through the injection cylinder, sufficiently kneaded by the second screw 10 and plasticized to perform the following action in a state where the injection condition is satisfied. .

(1) The second screw 10 rotates slowly, the material resin is extruded from the gap 11 through the first cylinder portion 2, and the first screw 4 is swiftly rotated at a speed commensurate with the amount of extrusion that flows in through the gap 11. A certain amount of the material resin that has retreated and melted is accumulated at the tip of the first screw 4.

(2) Next, the first screw 4 is advanced by the drive of the hydraulic cylinder 34 of the drive unit 35 for injection, and the material resin is injected from the nozzle portion 2a into the mold. At this time, the second screw 10 and the first screw 4 are slowly rotated to maintain the resin pressure.

(3) After a certain period of time, the resin in the mold is solidified, the rotations of the second screw 10 and the first screw 4 are stopped, and the first screw 4 is slightly retracted due to suck back.

(4) The mold is opened, the molded product is taken out, the mold is clamped again, and the process returns to the first step (1) to repeat each step. The rotation speeds of the second screw 10 and the first screw 4 can be independently set according to the type of resin raw material and the plasticizing conditions.

As described above, in the injection molding machine of the present embodiment, since the screw diameter of the second screw 10 can be made large, a large amount of resin can be extruded and it can be applied to a large molded product. Further, since the material resin is injected from the nozzle portion 2a into the mold, the first screw 4 is rotated so as to return the molten material resin to the tip direction even if the pressure in the first cylinder portion 2 becomes high. Since the resin pressure is maintained, the molten material resin is applied to the cylindrical shaft 20 behind the first screw 4.
There is no risk of leakage from the fitting gap between the second screw 10 and the second screw 10.

Next, FIG. 3 is a side sectional view showing a second embodiment of the injection molding machine of the present invention, and FIG. 4 shows the first cylinder portion and the second cylinder portion of the embodiment shown in FIG. It is a bird's-eye view around the drive mechanism. The injection molding machine of this embodiment also
It has a structure that combines an injection molding unit and a screw extrusion device.

The present embodiment is different from the above-described first embodiment in the structure, that is, the extruding screw 30 provided on the outer peripheral surface of the first screw 4'in the portion housed inside the first cylinder portion 2. ′, The internal screw provided on the outer peripheral surface of the first screw 4 ′ in the portion passing through the through hole 25 of the second screw 10 is provided over the entire portion passing through the through hole 25. Internal screw 36, the second
The screw 10 'also serves as the injection cylinder of the first screw 4', the cross roller bearing 29 as a thrust bearing provided on the lid 23 of the second cylinder portion 3 ', and the first screw 4'. That is, the bearing stand 37 is installed between the hydraulic cylinder 34 which is the movement drive means and the drive unit 35 which is the first screw drive motor 32 which is the rotation drive means.

The bearing base 37 is provided with a bearing 40 which supports the rear end portion of the second screw 10 'which extends rearward from the portion pivotally supported by the cross roller bearing 29 through the lid 23. At the same time, the resin charging port 38 is provided in the radial direction, and on the outer peripheral surface where the resin charging port 38 opens,
A second hopper 40 is provided. Further, the bearing base 37 is formed with a full-through internal screw 36 protruding from the rear end of the second screw 10 ′ axially supported by the bearing 40.
While accommodating the outer peripheral portion of the screw 4 ′, the second material resin supplied from the resin input port 38 is supplied to the second screw 1
A sending portion 39 for feeding the inside of 0'is provided.

A short cylindrical shaft 41 is provided at the rear of the whole internal screw 36 forming portion of the first screw 4'which penetrates the bearing base 36.
Is provided to support the first screw 4'and prevent leakage of the second material resin supplied to the delivery portion 39 in front of the first screw 4'to the rear of the bearing base 36. It is not always necessary to provide the all-internal screw 36 on the outer peripheral surface of the first screw 4 ', which projects from the second screw 10' and is inserted into the delivery portion of the bearing base 37. Bearing stand 37
Is fixed to the unit base 16 and the inner diameter of the horizontal through hole of the bearing base 37 is equal to the through hole provided in the second screw 10 '.
That is, it has the same size as the inner diameter of the injection cylinder of the first screw.

Next, the operation of the injection molding machine of the second embodiment will be described. The nozzle portion 2a of the first cylinder 2 is pressed against the resin inlet of the clamped mold of the injection molding machine, and the raw material resin introduced into the hopper 9 and the second hopper 41 is stored inside the second cylinder portion 3 and The following action is performed in a state where the second screw 10 ′ enters the inside thereof and is heated while being sent toward the tip of both of them, sufficiently kneaded, plasticized and satisfying the injection condition.

(1) The second screw 10 'rotates slowly, and the resin amount obtained by adding the resin extrusion amount of the second screw 10' to the resin delivery amount of the first screw 4'is extruded and stored at the tip of the first screw 4 '. .

(2) Next, the first screw 4'is moved forward for injection, and the material resin is injected from the nozzle 2a into the mold. At this time, the second screw 10 and the first screw 4'are slowly rotated to maintain the resin pressure.

(3) After a certain period of time has elapsed and the material resin in the mold has solidified, the rotation of the second screw 10 'and the first screw 4'is stopped, and the first screw 4'is slightly retracted due to suck back. To do.

(4) The mold is opened, the molded product is taken out, the mold is clamped again, the process returns to the first step (1), and each step is repeated. The rotation speeds of the second screw 10 'and the first screw 4'can be independently set according to the type of resin raw material and the plasticizing conditions.

In the case of this injection molding machine, the amount of resin stored at the tip of the first screw 4'during injection is the sum of the amount of resin delivered from the first screw 4'and the amount of resin delivered from the second screw 10 '. Since the amount of resin is different, a section for storing the material resin at the tip of the first screw 4 ', that is, the first screw 4'
It can be applied to a larger molded product by increasing the amount of movement of the rearward of. In addition, the hopper 9 and the second hopper 40
It is also possible to add different types of material resins to each of the above and melt-knead them in a kneading state or a plasticized state suitable for each material resin, and mix them to form a molded product.

[0059]

As described above, according to the injection molding machine of the present invention, the following effects can be obtained with the configuration shown in the claims.

(1) A high-kneading, high-plasticization injection molding machine is obtained by using a double cylinder injection cylinder in which a large-diameter second screw and a small-diameter first screw are concentrically doubled. And can be applied to large molded products.
Compared to conventional equipment with the same capacity, such an injection molding machine
The installation area is small, and since the double cylinders are heated by the same heater to avoid wasteful heat dissipation, the amount of heat is effectively used and energy consumption is small.

(2) Further, since the extruding screw of the first screw is provided up to the inside of the through hole of the second screw, the molten resin does not flow backward toward the front.

(3) Further, since the rotation speeds of the first screw and the second screw can be independently set, the kind of resin raw material and the plasticizing condition can be easily accommodated.

(4) Furthermore, the hydraulic oil that drives the second screw in the axial direction is not used, and the hydraulic oil that drives the first screw in the axial direction is separated from the kneading and plasticizing compartments. Since it is operated, the working oil does not leak to the material resin side, and further, it is never mixed with the material resin.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a first embodiment of an injection molding machine of the present invention,

FIG. 2 is a plan view of the second cylinder having the configuration shown in FIG. 1, and a periphery of a driving mechanism portion of the first screw and the second screw;

FIG. 3 is a side sectional view showing a second embodiment of the injection molding machine of the present invention,

FIG. 4 is a plan view (part) of the periphery of the drive mechanism portion of the second cylinder, the first screw, and the second screw in the form shown in FIG.

FIG. 5 is a side sectional view showing a plasticizing device of a conventional high-kneading injection molding machine,

6 is a configuration diagram showing an operation of a throttle gap of the plasticizing device shown in FIG.

[Explanation of symbols]

1,01 Injection cylinder 2,02 First cylinder part (small diameter) 3,03 Second cylinder part (large diameter) 4,4 ', 04 First screw (small diameter) 9,09 Hopper 10,10', 010 Second Screw (large diameter) 11,011 (Throttle) gap 15 Molding device body 16 Unit stand 17 (For injection molding unit) Hydraulic cylinder 18 Pedestal 19 Heating heater 20 Cylindrical shaft 21 Resin injection hole 22 Drive chamber 23 Lid 24 (No. 2 screw) Extrusion screw 25 Through hole 26 Large-diameter gear (of second rotation drive means) 27 Pinion (of second rotation drive means) 28 Second screw drive motor 29 (of second rotation drive means) 29 As thrust bearing Cross roller bearing 30, 30 'Extrusion screw (of first screw) 31 Partial internal screw 32 First as first rotation driving means
Screw drive motor 33 Bracket 34 Hydraulic cylinder as movement drive means 35 Drive unit 36 All-through internal screw 37 Bearing base 38 Resin injection port 39 Feeding part 40 Bearing 41 Second hopper

Claims (4)

[Claims] 1. A first cylinder portion for accommodating a tip portion of a first screw, which is provided with a nozzle portion at its tip, is axially movable inside, and is rotatable, and the first cylinder portion. A second screw, which has a larger diameter, is connected to the rear end of the first cylinder portion, and rotates around the outer periphery of the first screw having an axial center portion penetrating therein, is accommodated by the rotation of the second screw. A second cylinder portion provided with a conical annular gap for supplying the material resin supplied inside from a hopper provided on the outer peripheral surface to the tip portion of the first screw on the inner peripheral surface of the tip position of the second screw. And a thrust bearing that is provided at the rear end portion of the second cylinder portion and that rotatably supports the second screw while restraining the movement in the axial direction. The thrust bearing in front of the A second cylinder which is installed in the vicinity of a drive chamber defined in the two-cylinder part and which rotates the second screw.
A rotary drive means and a shaft center portion of the second screw,
The first screw is installed at the rear end of the first screw and protrudes rearward from the rear end of the second cylinder part.
An injection molding machine, comprising: a drive unit for moving in an axial direction; and a drive unit provided with a first rotary drive unit for rotating. 2. A gear fixed to the outer periphery of the second screw, wherein the second rotation drive means penetrates the drive chamber,
The injection molding machine according to claim 1, further comprising a pinion that meshes with the gear, and a reduction motor having the output shaft fixed to the pinion. 3. The first screw is continuous with a helical extrusion screw formed on the outer peripheral surface of the accommodating portion of the first cylinder portion, and extends through the axial center portion of the second screw. Partial internal screw wound around the outer peripheral surface 2-3, and cylindrical from the rear end of the partial internal screw,
The injection molding machine according to claim 1 or 2, further comprising a cylindrical shaft that penetrates the second screw and projects rearward from a rear end of the second cylinder. 4. The entire internal passage formed on the outer peripheral surface of the first screw from a spiral screw formed on the outer peripheral surface of the accommodating portion of the first cylinder to a rear end of the second screw. A bearing, which is provided between the thrust bearing and the drive unit, supports a rear end of the second screw protruding rearward from the thrust bearing, and a rear end portion of the all-through internal screw. The injection molding machine according to claim 1 or 2, characterized in that a bearing base having a second hopper for supplying a second material resin to the first screw is provided on the outer peripheral surface.