JPH10305461A - Screw-in-plunger type injection device and operation controlling method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably mold a product with excellent quality by a method wherein both the forward driving force and forward speed of an injection plunger are adjusted to become below pre-set limit values by passing the pre-set changing-over position at the forward driving of the injection plunger. SOLUTION: When an injection plunger 12 passes the pre-set changing-over position during the forward action of the injection plunger 12, the forward action of the injection plunger 12 is automatically performed at slow speed and by low pressure. As a result, the injection plunger 12 is brought into close contact at slow speed and low pressure with the tapered inner surface 18 of the injection cylinder 14. Thus, even under the condition that the accuracy of the dimensions of parts is not high, the dimensions of the parts change due to the thermal expansion of the parts and the like, the impactive abutment of the injection plunger 12 against the injection cylinder 14 is fully avoided and the favorable contact of the injection plunger 12 with the injection cylinder 14 is realized. Accordingly, this device has effects of heading off the thermal deterioration of a resin material due to the prevention of the resin material from entering between the injection plunger 12 and the injection cylinder 14 and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical injection plunger which is inserted into an injection cylinder so as to be able to move forward and backward, and further rotatably inserts a screw into the injection plunger. The present invention relates to a screw-in plunger type injection device for injecting a molded resin material by advancing an injection plunger and a screw, and a method of controlling the operation thereof.

[0002]

2. Description of the Related Art Conventionally, as a kind of injection apparatus for manufacturing a desired molded product by injection-filling a molten molding resin material into a molding cavity of a predetermined mold, Japanese Patent Publication No. Sho 46 (1988) is known.
As described in JP-A-2909 and JP-A-60-171319, a screw is rotatably inserted into a cylindrical injection plunger inserted and arranged in an injection cylinder, and the molding resin is formed by rotation of the screw. A screw-in plunger-type injection system that injects the resin material in the storage section by feeding the material into the storage section on the tip side of the injection plunger and simultaneously advancing the injection plunger and the screw in the injection cylinder simultaneously and integrally. Devices are known.

Incidentally, the injection plunger in such a screw-in plunger type injection device is operated at a high speed in the axial direction at the time of injection or the like for the purpose of improving the molding cycle and the like. However, the injection plunger is operated at a high speed in a forward direction. In such a case, if the tip portion contacts the injection cylinder, a problem such as damage to mechanical parts may occur. Therefore, conventionally, a small gap is generally set between the tip of the injection plunger and the injection cylinder at the forward end position of the injection plunger so that the tip of the injection plunger does not contact the injection cylinder. Here, the size of the gap is determined by the dimensional variation at the time of replacement due to the tolerance of the part and the thermal expansion /
Since it is necessary to set the injection plunger and the injection cylinder to completely avoid contact in consideration of dimensional changes due to shrinkage, etc., it is difficult to make the injection plunger sufficiently small. Thus, a gap is formed.

However, if a gap of such a size exists between the injection plunger and the injection cylinder, the molding resin material that has entered the gap cannot be completely removed by the injection operation but remains until the next injection operation. Becomes Then, the molding resin material remaining in the gap tends to be thermally degraded due to a long heat history time, so that there is a possibility that the quality of the molding resin material and, consequently, the quality of the product is reduced. Further, since the molding resin material remains in the gaps, there is a problem that much time and resin are required when changing the color or the material of the molding resin material.

[0005]

Here, the present invention has been made in view of the above-mentioned circumstances, and the object of the present invention is to provide an injection plunger and an injection cylinder. This eliminates the problems caused by the infiltration and residual of the molding resin material into the gap, stabilizes the molding of excellent quality products, and makes it easy to change the molding resin material. It is to provide a plunger type injection device.

Further, the invention according to claim 5 prevents the molding resin material from entering and remaining between the injection plunger and the injection cylinder while preventing damage to parts caused by the contact between the injection plunger and the injection cylinder. Control method of a screw-in plunger type injection device that can stably mold products of excellent quality and also advantageously improves workability such as changing the molding resin material. The purpose is to provide.

[0007]

In order to solve such a problem, a feature of the invention according to claim 1 is that a cylindrical injection plunger is inserted into an injection cylinder so as to be able to advance and retreat in an axial direction. And a screw is inserted into the injection plunger, and by the rotation of the screw, a molding resin material is fed into a storage portion on the tip side of the injection plunger, and the injection in the injection cylinder is performed. By the advance of the plunger and the screw,
In the screw-in plunger type injection device in which the molding resin material in the storage section is injected, an axial end surface of the injection plunger is in close contact with an inner surface of the injection cylinder at a forward end position thereof. In addition, when the injection plunger is driven forward, the forward drive force and forward speed of the injection plunger are both set to be equal to or less than a preset limit value at a predetermined switching position. The plunger drive control device that adjusts the pressure is provided.

[0010] In the screw-in plunger type injection device having the structure according to the first aspect of the present invention, at least before the injection plunger comes into contact with the injection cylinder, the forward driving force and the forward moving speed of the injection plunger are reduced. As a result, the distal end surface of the injection plunger approaches and contacts the front inner surface of the injection cylinder at a low speed, and comes into close contact with a small force.

Therefore, in such an injection device, it is possible to hold the injection plunger in close contact with the injection cylinder while avoiding damage to parts caused by the impact of the injection plunger against the injection cylinder.
Since the molding resin material is advantageously prevented from remaining between the injection plunger and the injection cylinder, thermal degradation of the resin material due to an increase in heat history time is reduced or avoided, and
It is possible to advantageously improve the workability and shorten the work time when changing the color or material of the molding resin material.

In addition, by appropriately adjusting the switching position between the driving force and the speed of the injection plunger, a molding cycle can be advantageously secured.

The invention described in claim 2 is the first invention.
In the injection device having the structure according to the invention described in (1), the distal end inner surface of the injection cylinder is a tapered inner surface having a tapered shape, and the distal end surface of the injection plunger is located on the tapered inner surface of the injection cylinder. A corresponding tapered end surface is formed, and the injection plunger is advanced so that the tapered end surface comes into close contact with the tapered inner surface of the injection cylinder. And As described above, by making the inner surface on the distal end side of the injection cylinder and the distal end surface of the injection plunger that are in contact with each other a corresponding tapered surface, the contact surfaces between the injection cylinder and the injection plunger can be more stably and intimately contacted. They are hurried.

Further, the invention described in claim 3 is the first invention.
Or an injection device having a structure according to the invention described in 2 above, wherein the distal end surface of the screw has a shape corresponding to the inner surface on the distal end side of the injection cylinder, and at the forward end position of the screw, It is characterized in that a gap is interposed between the tip surface and the inner surface on the tip side of the injection cylinder. By setting such a gap, damage to parts caused by the contact of the screw with the injection cylinder can be advantageously avoided. The size of the gap is set to be sufficiently small in consideration of dimensional errors of components, heat shrinkage, and the like. For example, in a general injection device, it is set to about 1 mm. Preferably, the distal end surface of the screw is a tapered end surface having a sharp shape, and the inner surface on the distal end side of the injection cylinder is a tapered inner surface having a tapered shape. By adopting such a tapered shape, the gap between the screw tip surface and the injection cylinder inner surface can be set sufficiently small, and the damage in the event of contact can be advantageously suppressed.
If the gap between the tapered end surface and the tapered inner surface is set to be slightly larger toward the distal end, the injection of the resin material can be more advantageously performed.

The invention described in claim 4 is the first invention.
4. The injection device according to any one of claims 1 to 3, wherein the screw is relatively movable in the axial direction with respect to the injection plunger, and a tip end surface of the injection plunger in the axial direction is the injection cylinder. By retracting the screw in a state where the screw is in contact with the inner surface of the injection cylinder, a reduced storage portion is formed at the tip side of the injection screw in the injection cylinder, and the screw is connected to the injection plunger. On the other hand, there is provided a screw driving means for driving in the axial direction, and the molding resin material fed into and stored in the reduced storage portion by the rotation of the screw is injected by the axial advance operation of the screw. Is characterized by the following.

[0014] In the injection device having the structure according to the fourth aspect of the invention, the screw is rotated and rotated in the axial direction while the tip end surface of the injection plunger is fixed in close contact with the inner surface of the injection cylinder. By moving
General in-line screw injection molding can be performed. That is, in such an injection device, a conventional plunger-type injection operation for injecting the molten resin in the storage portion by advancing the injection plunger and the screw in the injection cylinder, and fixing the injection plunger in contact with the injection cylinder. By rotating and axially moving the screw in the closed state, an in-line screw type injection operation for injecting the molten resin in the reduced storage portion can be selectively performed. Here, the screw inserted into the injection plunger has a smaller outer diameter than the injection plunger. The stroke is advantageously secured, and good controllability and molding stability can be obtained.By selecting the plunger-type injection operation or in-line screw-type injection operation, large products with a large injection amount can be obtained. It is possible to stably and continuously mold both small products and small injection quantities with excellent controllability of the injection quantity and the like.

In particular, in the injection device having the structure according to the fourth aspect of the present invention, when performing the in-line screw type injection operation, the tip of the injection plunger is advantageously in close contact with the injection cylinder. Therefore, the backflow of the resin material through the gap between the tip of the injection plunger and the injection cylinder is extremely advantageously prevented, resulting in defects such as resin leakage and molding defects such as sink marks caused by the resin leakage. Can also be effectively eliminated. In order to sufficiently withstand the injection pressure during the in-line injection operation, after the injection plunger is stopped from moving forward after the injection plunger contacts the injection cylinder, the forward drive force of the injection plunger is increased again. Thus, the contact pressure of the injection plunger with respect to the injection cylinder may be set high.

In the invention according to claim 4, the ratio of the cross-sectional area of the insertion hole of the injection plunger in the injection cylinder: Sa to the cross-sectional area of the insertion hole of the screw in the injection plunger: Sb: Sa / Sb. When the value is 2 ≦ Sa /
The ratio of the maximum capacity of the storage section formed at the distal end side of the injection plunger: Qa to the maximum capacity of the storage section formed at the distal end side of the screw: Qb so that Sb ≦ 8:
If the value of Qa / Qb is set to satisfy 3 ≦ Qa / Qb ≦ 10, a particularly large required injection amount width (range) can be selected by selecting a plunger type injection operation or an inline screw type injection operation. , A good moldability can be obtained. That is, by setting 2 ≦ Sa / Sb, the effect that a large volume of molten resin can be stored and molded using a relatively small injection plunger can be more advantageously achieved, and 3 ≦ Qa / By setting Qb, the corresponding range of the required injection amount (molding cavity volume) is more advantageously secured, and excellent economical effects and cost performance are exhibited. On the other hand, by setting Sa / Sb ≦ 8 or Qa / Qb ≦ 10, the storage time of the resin material in the storage part becomes too long, or the distance from the external heater for controlling the temperature of the storage part to the central part of the storage resin is reduced. It is prevented from becoming too long, whereby the temperature difference of the stored resin at the beginning and end of the storage, or at the center and the extension, is suppressed, and more stable moldability is achieved. It is secured. Moreover, Sa / Sb ≦ 8 or Qa / Qb ≦
With a value of 10, it is possible to further advantageously prevent an increase in the cycle time caused by an increase in the storage capacity and an excessively long time required for storage.

Further, the invention according to claim 5 has been made in order to solve the above-mentioned problem, and a feature of the invention is that a cylindrical injection plunger is provided on a shaft with respect to an injection cylinder. The screw is inserted into the injection plunger so as to be able to advance and retreat in the direction, and by the rotation of the screw, the molding resin material is fed into the storage portion on the tip side of the injection plunger, In the screw-in plunger type injection device in which the molding resin material in the storage section is injected by the advancement of the injection plunger and the screw in the injection cylinder, the injection plunger is driven when the injection plunger is driven forward. When a predetermined switching position is reached, the forward driving force and forward speed of the injection plunger. In either case, the injection plunger is advanced at a low power and a low speed by adjusting the injection plunger to a predetermined limit value or less, so that the axial front end surface of the injection plunger is densely arranged with respect to the inner surface of the injection cylinder. An operation control method of a screw-in plunger type injection device to be brought into contact.

According to the fifth aspect of the present invention, when the injection plunger moves forward, the injection plunger can move at high speed until it reaches the switching position.
After switching to low speed and low power, the distal end face of the injection plunger is brought into close contact with the injection plunger. Therefore, the tip of the injection plunger can be smoothly brought into close contact with the front inner surface of the injection cylinder while sufficiently ensuring an excellent molding cycle. Since the molding resin material is prevented from remaining during the process, it is possible to extremely advantageously avoid defects such as thermal deterioration of the resin material, improve the workability of changing the resin material, and the like.

[0019]

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

First, FIG. 1 schematically shows a specific configuration example of a screw-in plunger type injection device as one embodiment of the present invention. This injection device includes a cylindrical injection plunger 12 into which a screw 10 is inserted, and a tip side of the injection plunger 12 is inserted so as to be able to be inserted into and removed from an inner hole 16 of a hollow injection cylinder 14. I have. FIG. 1 is a vertical cross-sectional view of a horizontal cut surface in a state where the screw 10 and the injection plunger 12 are both positioned at the forward end which is the direction of insertion into the injection cylinder 14. . In the following description, the left side and the right side in FIG. 1 are referred to as front and rear, respectively.

More specifically, the injection cylinder 14 has a thick cylindrical shape, and the tip of the inner hole 14 is a tapered inner surface 18 of a tapered funnel shape. Also,
The tip of the injection cylinder 14 has a small-diameter nozzle 20.
A nozzle hole 22 penetrating through the nozzle portion 20 and extending forward from the tip of the inner hole 16 is formed. Furthermore, the injection cylinder 14 is located on both sides of the inner hole 16 so that the first hydraulic cylinder mechanism 2
4, 24 are provided integrally. A band heater 26 for heating is wound around the outer peripheral surface of the injection cylinder 14.

Although not shown, the injection cylinder 14 is supported by a predetermined base so as to be movable in the axial direction, and the tip of the injection cylinder 14 is opposed to a mold clamping device (not shown). It is arranged as follows. Then, the injection cylinder 14 is driven in a direction approaching and away from the mold supported by the mold clamping device by a nozzle touch hydraulic cylinder mechanism (not shown), and the nozzle portion 20 is brought into nozzle contact with the mold. It is designed to be fixedly supported in the state in which it is performed.

On the other hand, the injection plunger 12 has a substantially cylindrical shape, and its outer diameter is slightly smaller than the inner diameter of the inner hole 16 of the injection cylinder 14. 16 is fitted so as to be movable in the axial direction. In addition, injection plunger 1
2 has a tapered end surface 28 which is tapered. The inclination angle of the tapered end surface 28 is substantially the same as the inclination angle of the tapered inner surface 18 of the injection cylinder 14, and the injection plunger 12 moves forward. When positioned at the end, the tip surface (tapered end surface) 28 of the injection cylinder 1
4 so as to be in close contact with the inner surface 18 of the taper. Further, the proximal end side of the injection plunger 12 is
The resin material is supplied to the inside of the inner hole 30 of the injection plunger 12 through a material charging hole provided in the protruding portion, although not shown in the drawing. It has become so.

Also, at the base end of the injection plunger 12,
A moving block 32 is fixed, and piston rods 34, 34 of first hydraulic cylinder mechanisms 24, 24 provided on the injection cylinder 14 are fixed to the moving block 32.
, Respectively, are fixed. Accordingly, the injection plunger 12 is moved by the first hydraulic cylinder mechanisms 24, 24.
Can be moved forward / backward in the inner hole 16 of the injection cylinder 14, and in particular, in each first hydraulic cylinder mechanism 24, the piston 38 is moved forward (the retraction side of the piston rod 34). By this time, the distal end surface 28 of the injection plunger 12 comes into contact with the tapered inner surface 18 of the injection cylinder 14 so that the forward end position of the injection plunger 12 is defined. Thus, when the injection plunger 12 is positioned at the forward end, a contact pressure is applied between the injection plunger 12 and the contact surfaces 18 and 28 of the injection cylinder 14 by the first hydraulic cylinder mechanisms 24 and 24. That is to say.

Further, the screw 10 inserted into the inner hole 30 of the injection plunger 12 has the same structure as that conventionally used for a screw in an in-line screw type injection device, and has a spiral outer peripheral surface. The screw thread 36 extending in the shape of a screw is integrally provided, and the outer diameter of the screw thread 36 is determined by the injection plunger 12.
The inner diameter of the inner hole 30 is slightly smaller than
It is fitted into the inner hole 30 of the injection plunger 12 so as to be movable in the axial direction and rotatable around the central axis.

A connecting rod 40 having a circular rod shape is fixed to the base end of the screw 10. Further, a piston block 42 and a guide plate 44 are attached to the connection shaft 40 so as to be relatively non-displaceable in the axial direction while allowing rotation about the center axis of the connection shaft 40. Then, the piston block 42 is connected to the cylinder 4 formed in the moving block fixed to the base end of the injection plunger 12.
A second hydraulic cylinder mechanism 48 is configured to be slidably fitted to the second hydraulic cylinder 6 to reciprocally drive the screw 10 in the axial direction. Also, with respect to the guide plate 44,
Piston rod 3 of first hydraulic cylinder mechanism 24, 24
4 and 34 are inserted, and piston rods 34 and 34 are inserted.
The screw 10 is guided in the axial direction by sliding the guide plate 44 in the axial direction. Further, an output shaft 52 of a hydraulic motor 50 fixed to the base end of the piston block 42 is attached to the connecting shaft 40, and the rotational driving force of the hydraulic motor 50 is transmitted through the connecting shaft 40 to the screw. By being transmitted to the screw 10, the screw 10 is driven to rotate around the central axis.

In short, the screw 10 is connected to the hydraulic motor 5
0, the injection plunger 12 is driven to rotate around the central axis, and the second hydraulic cylinder mechanism 48 allows the injection plunger 12 to be relatively moved in the axial direction. is there. And
By the rotation operation of the screw 10 in the injection plunger 12, the resin material supplied into the inner hole 30 of the injection plunger 12 is heated and melted while being sent forward. In addition, at the tip of the screw 10,
A backflow prevention valve 54 for preventing backflow of the molten resin in the injection plunger 12 is provided.

The distal end surface of the screw 10 has a sharp tapered end surface 56 corresponding to the tapered inner surface 18 of the inner hole 16 of the injection cylinder 14, and the injection plunger 12 is positioned at the forward end. Below, when the piston block 42 of the second hydraulic cylinder mechanism 48 is moved to the forward end, and the screw 10 is positioned at the forward end, the taper end surface 56 of the screw 10 and the taper inner surface of the injection cylinder 14 The length of the screw 10 is set so that a slight gap is formed between the screws 18. Thereby, the contact of the screw 10 with the injection cylinder 14 is avoided.

The size of the gap between the tapered end surface 56 of the screw 10 and the tapered inner surface 18 of the injection cylinder 14 is determined by taking into account the dimensional tolerance and thermal expansion of the parts, even when the parts are replaced or heated. It is desirable that the gap is set to be sufficiently small within a range in which the gap is prevented, and the gap is generally formed with a size of about 1 mm. Further, the inclination angle of the tapered end surface 56 of the screw 10 is slightly larger than the inclination angle of the tapered inner surface 18 of the injection cylinder 14, and the gap between the tapered end surface 56 of the screw 10 and the tapered inner surface 18 of the injection cylinder 14 is reduced. When the screw 10 is driven forward, the resin material is efficiently extruded from the nozzle hole 22 by being set so as to gradually increase toward the distal end side.

That is, in the injection apparatus having the above-described structure, as shown in FIG. 2, the injection plunger 12 is driven in the axial direction by the first hydraulic cylinder mechanisms 24, 24, and the injection cylinder is driven. By inserting a predetermined amount into the injection cylinder 14, a storage portion 58 having a predetermined volume is formed at the tip end side of the injection plunger 12 in the injection cylinder 14.
By rotating the screw 10, the resin material supplied into the inner hole 30 of the injection plunger 12 is heated and melted, sent forward, and guided to the storage section 58. Then, after a predetermined amount of molten resin is stored in the storage section 58, the first hydraulic cylinder mechanisms 24, 24 and the second hydraulic cylinder mechanism 48 are simultaneously operated, and are indicated by phantom lines in FIG. Injection plunger 12
And the screw 10 are driven forward at the same time,
The injection plunger 12 and the screw 10 cooperate to function as a plunger, so that the molten resin stored in the storage part 58 is injected through the nozzle hole 22, whereby molding by the plunger type injection mechanism is performed. It is like that.

When molding is performed by such a plunger type injection mechanism, the screw 10 is generally positioned at the forward end relative to the injection plunger 12, so that the screw 10 and the injection plunger are used for injection. 1
2 can be simultaneously moved in the axial direction. However, when a larger amount of injection resin is required, the screw 10 is retracted relative to the injection plunger 12 in the axial direction, and the It is also possible to secure a large volume 58 and to move the screw 10 relative to the injection plunger 12 axially forward during injection.

On the other hand, in the injection device having the above-described structure, as shown in FIG. 3, the injection plunger 12 is inserted into the injection cylinder 14, and the first hydraulic cylinder mechanisms 24, 24 By driving the injection plunger 12 in the axial direction, the tapered end surface 28 at the tip end of the injection plunger 12 is moved to the forward end where it abuts against the tapered inner surface 18 of the inner hole 16 of the injection cylinder 14, and these tapered end surfaces 28 and By keeping the tapered inner surface 18 in close contact, the inner diameter of the inner hole 16 of the injection cylinder 14 is reduced substantially by the thickness of the injection plunger 12, whereby the screw 10
A reduced storage section 60 having a smaller volume than the storage section 58 is formed on the distal end side of the storage section 58. By rotating the screw 10 while the injection plunger 12 is positioned at the forward end in this manner,
The resin material is heated and melted in the injection plunger 12, sent forward, and guided to the reduced storage section 60. Further, after the screw 10 is retracted by a predetermined amount by the pressure of the resin material guided to the reduced storage section 60 and a predetermined amount of molten resin is stored in the reduced storage section 60, the second hydraulic cylinder mechanism 48 The screw 10 functions as a plunger by causing the screw 10 to move forward as indicated by the phantom line in FIG. The molding is performed by an in-line screw type injection mechanism.

In short, in the injection device having the above-described structure, the molding by the plunger type injection mechanism and the molding by the in-line screw type injection mechanism can be appropriately selected and carried out. Effective plunger diameter in the mechanism (injection plunger 1
2) is set sufficiently larger than the effective screw diameter (outer diameter of the screw 10) in the in-line screw type injection mechanism, and the maximum metered resin amount of the injection plunger 12 in the plunger type injection mechanism (ie, Since the maximum metered resin amount of the screw 10 (that is, the maximum capacity of the reduced storage section 60) in the in-line screw injection mechanism can be set smaller than the maximum capacity of the storage section 58, the size of the molded product can be reduced. By selecting the molding by the plunger type injection mechanism or the molding by the in-line screw type injection mechanism according to the above, the injection plunger 1 can be used for molding both small products and large products having different required amounts of injection resin.
This makes it possible to set the measuring stroke of the screw 2 or the screw 10 to a preferable range.

In such an injection device, the injection plunger 12 is used for injection at the time of molding by the plunger type injection mechanism, or when changing from molding by the plunger type injection mechanism to molding by the in-line screw type injection mechanism.
Is driven forward, and the tapered end surface 28 of the injection plunger 12 is brought into close contact with the tapered inner surface 18 of the injection cylinder 14. Thereby, the injection plunger 12
Of the injection cylinder 14 and the tapered inner surface 18 of the injection cylinder 14
Is substantially eliminated, thereby preventing the resin material from entering the gap.

Therefore, even during continuous injection molding by the plunger type injection mechanism, the molding resin material is prevented from remaining between the tapered end surface 28 of the injection plunger 12 and the tapered inner surface 18 of the injection cylinder 14. Thermal degradation of the resin material due to such residue is avoided, and excellent product quality can be advantageously secured. In addition, since the amount of residual resin after injection in the injection cylinder 14 is suppressed, there is an advantage that the time and labor for changing the color and material of the molding resin material are advantageously reduced.

In particular, during injection molding by the in-line screw type injection mechanism, leakage of the molding resin material through the gap between the tapered end surface 28 of the injection plunger 12 and the tapered inner surface 18 of the injection cylinder 14 is advantageously prevented. In addition, it is possible to effectively eliminate problems such as occurrence of molding defects such as sink marks due to such leakage and operation failure and contamination due to leakage resin.

Here, the injection plunger 12
1 is driven by a first hydraulic cylinder mechanism 2 which is a reciprocating cylinder by a hydraulic circuit as shown in FIG.
The operation is performed by switching the supply and discharge of the hydraulic oil to the valves 4 and 24 by the electromagnetic switching valve 62.
The advance speed of the injection plunger 12 is changed and adjusted by the control device 74. That is, the forward drive side cylinder chamber 6 in each first hydraulic cylinder mechanism 24
A hydraulic pump 70 and an oil tank 72 (drain) are provided in the cylinder drive chamber 6 and the retraction drive side cylinder 68 via an electromagnetic switching valve 62.
The injection plunger 12 is moved forward and backward by switching the electromagnetic switching valve 62 by the control device 74. Although not explicitly shown in the drawings, a hydraulic circuit for supplying and discharging hydraulic oil to and from a second hydraulic cylinder mechanism 48 for driving the screw 10 forward and backward and a hydraulic motor 50 for rotating the screw 10 are also provided. The second hydraulic cylinder mechanism 48 and the hydraulic motor 5 are used so that the intended injection molding operation is put to practical use.
The supply and discharge of hydraulic oil to and from the first hydraulic cylinder mechanisms 24 and 24 are performed by the control device 74 in association with the supply and discharge of hydraulic oil to and from the first hydraulic cylinder mechanisms 24 and 24.

Further, a flow control valve 7 is provided in a supply path of hydraulic oil from the hydraulic pump 70 to the first hydraulic cylinder mechanism 24.
6, the supply flow rate of the hydraulic oil to the first hydraulic cylinder mechanism 24 and, consequently, the drive speed of the injection plunger 12 by the first hydraulic cylinder mechanism 24 can be adjusted based on the control by the control device 74. ing. Further, a pressure control valve 78 is provided in a supply path of the hydraulic oil from the hydraulic pump 70 to the first hydraulic cylinder mechanism 24, and the pressure control valve 78 is provided to the first hydraulic cylinder mechanism 24 based on the control by the control device 74. And the driving force of the injection plunger 12 by the first hydraulic cylinder mechanism 24 can be adjusted.

In short, the drive speed and drive force of the injection plunger 12 are adjusted based on the operation control of the flow control valve 76 and the pressure control valve 78 by the control device 74. The driving speed and driving force of the injection plunger 12 are set in advance before the injection plunger 12 comes into contact with the injection cylinder 14 when the injection plunger 12 is moved forward to come into contact with the tapered inner surface 18 of the injection cylinder 14. It is switched and adjusted so as to be equal to or less than the limit value. That is, although not explicitly shown in the drawings, a position sensor for detecting the position of the injection plunger 12 is provided between the injection plunger 12 and the injection cylinder 14, and when the injection plunger 12 moves forward. When the injection plunger 12 is moved forward to a preset switching position until it comes into contact with the tapered inner surface 18 of the injection cylinder 14, an output signal from the position sensor is input to the control device 74, The flow control valve 76 and the pressure control valve 78 are controlled so that the flow rate and the pressure of the hydraulic oil supplied to the first hydraulic cylinder mechanism 24 are equal to or less than a predetermined limit value. is there.

For example, a specific example of the forward drive control of the injection plunger 12 by the control device 74 during the injection operation will be described with reference to the flowchart shown in FIG. First, when an injection control command is input in step 1 and hydraulic oil is supplied to the forward drive side cylinder chamber 66 of the first hydraulic cylinder mechanism 24, the injection plunger 12 is caused to advance, and in step 2, It is determined whether or not the current position AD of the injection plunger 12 detected by a position sensor (not shown) has reached a switching position SD previously set and stored. The switching position SD is, of course, set to a position until the injection plunger 12 comes into contact with the tapered inner surface 18 of the injection cylinder 14, but from the viewpoint of securing a molding cycle and the like, such a contact position is set. Is set sufficiently close to, for example, the injection plunger 12 that abuts the injection cylinder 14.
About 1 to 3 mm before the position of the forward end.

Then, the current position of the injection plunger 12:
If AD has not reached the switching position: SD, in steps S3 and S4, a forward control pressure value for injection operation: CP and a forward control flow value: CF, which are set as molding conditions in advance, are selected. , Pressure control valve 7
8 and output to the flow control valve 76, and the process ends.

On the other hand, the current position of the injection plunger 12: A
If D has reached the switching position: SD, in step S5, the advance control pressure value for injection operation: CP set as a molding condition in advance is compared with the advance limit pressure value: LP stored in advance. , Step S6 or Step S
At 7, the smaller of the forward control pressure value: CP and the forward limit pressure value: LP is selected and output to the pressure control valve 78.

Subsequently, in step S8, the forward control flow value for injection operation: CF set as a molding condition in advance is replaced with a forward limit flow value: LF stored and set in advance.
In step S9 or step S10, the forward control flow value: CF and the forward limit flow value: L
F, whichever is smaller, is selected, output to the flow control valve 76, and the process ends.

The forward limit pressure value: LP and the forward limit flow value: LF are the first hydraulic cylinder mechanisms 24, 24.
Considering the forward drive pressure and speed of the injection plunger 12 due to the above, the distal end surface (tapered end surface) of the injection plunger 12
The impact force when the abutment 28 abuts against the tapered inner surface 18 of the injection cylinder 14 is set so as to be sufficiently low so as not to cause damage to the members and the like.
The forward control pressure value: CP and the forward control flow rate value: CF, which can be set during the injection operation, are set to about 50% of the maximum values.

With such an operation control, when the injection plunger 12 moves forward, the injection plunger 12 automatically moves forward at a low speed and low power after the injection plunger 12 passes a preset switching position. As a result, the injection plunger 12 is brought into close contact with the tapered inner surface 18 of the injection cylinder 14 at low speed and low pressure (low force). In particular, since the forward speed of the injection plunger 12 is also limited after passing the switching position, the impact of the injection plunger 12 on the injection cylinder 14 can be reduced even in the case of an idling operation without the injection operation of the resin material. Contact is advantageously avoided.

Therefore, even if the accuracy of the component dimensions is not high,
Also, even if there is a dimensional change due to thermal expansion of the parts, etc., the impact contact of the injection plunger 12 to the injection cylinder 14 is completely avoided, and the parts are advantageously brought into close contact with each other. Effects such as avoiding thermal degradation of the resin material, facilitating change of the molding resin material, and preventing leakage of the molding resin material based on prevention of the resin material from entering between the injection plunger 12 and the injection cylinder 14 are all provided. It can be exerted very advantageously and stably.

As described above, one embodiment of the present invention has been described in detail. However, this is a literal example.
It should not be construed in a limited manner by the specific description in such an embodiment.

For example, as the first hydraulic cylinder mechanism 24, the second hydraulic cylinder mechanism 48, or the hydraulic motor 50 in the above-described embodiment, a driving means other than the hydraulic driving means such as an electric driving means using an electric motor or the like is employed. It is also possible. When the electric driving means is adopted, the forward speed and driving force of the injection plunger 12 can be restricted by restricting the supply voltage and the supply current to the electric driving means.

In the above-described embodiment, the screw 10 can be relatively displaced in the axial direction with respect to the injection plunger 12, so that the molding by the plunger type injection mechanism and the molding by the in-line screw type injection mechanism are selectively executed. Was able to do so,
As described in Japanese Patent Application Publication No. 09-2009, the present invention also relates to a screw-in plunger-type injection device having only a plunger-type injection mechanism because the screw 10 cannot be displaced relative to the injection plunger 12 in the axial direction. Can be applied in a similar manner. In addition, such an injection device is, for example,
In the injection device shown in the above-described embodiment, a hydraulic motor for rotatably supporting the screw 10 around the central axis by the moving block 32 and for driving the screw 10 without providing the second hydraulic cylinder mechanism 48. This can be realized by, for example, fixedly attaching the 50 to the moving block 32.

In addition, although not enumerated one by one, the present invention
Based on the knowledge of those skilled in the art, the present invention can be implemented in a form in which various changes, modifications, improvements, and the like are made.
It goes without saying that all such embodiments are included in the scope of the present invention without departing from the spirit of the present invention.

[0051]

As is apparent from the above description, in the screw-in plunger type injection apparatus having the structure according to the first to fourth aspects of the present invention, any of the abutting impacts caused by the forward movement of the injection plunger. The injection plunger can be held in close contact with the injection cylinder at a low speed and low pressure (low power) by suppressing the amount of resin material remaining in the injection cylinder during continuous injection molding. The heat deterioration of the material is advantageously reduced, and the workability for changing the molding resin material is also advantageously improved.

According to the fifth aspect of the present invention, the injection plunger can be operated at high speed until the injection plunger reaches the switching position, and the injection plunger can be operated after the switching position. The plunger is moved forward at a low speed and with a low force, so that the distal end surface is brought into close contact with the injection plunger. Therefore,
While ensuring an excellent molding cycle, the tip of the injection plunger can be brought into smooth and close contact with the front inner surface of the injection cylinder, and the amount of resin material remaining in the injection cylinder during continuous injection molding It is possible to advantageously reduce the thermal degradation of the resin material based on the decrease of the resin material, improve the workability of changing the molding resin material, and the like.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a screw-in plunger type injection device as one embodiment of the present invention.

FIG. 2 is an enlarged view of a main part for describing one operation state of the screw-in plunger type injection device shown in FIG.

FIG. 3 is an enlarged view of a main part for explaining another operation state of the screw-in plunger type injection device shown in FIG.

FIG. 4 is a flowchart for explaining a specific example of forward drive control of an injection plunger during an injection operation in the screw-in plunger type injection device shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Screw 12 Injection plunger 14 Injection cylinder 18 Tapered inner surface 24 First hydraulic cylinder mechanism 28 Tapered end face 48 Second hydraulic cylinder mechanism 50 Hydraulic motor 62 Electromagnetic switching valve 70 Hydraulic pump 76 Flow control valve 78 Pressure control valve

Claims (5)

[Claims] 1. A cylindrical injection plunger is inserted into an injection cylinder so as to be able to advance and retreat in the axial direction, and a screw is inserted into the injection plunger. A screw-in plunger in which a resin material is fed into a storage portion on the tip side of the injection plunger, and a molding resin material in the storage portion is injected by advancing the injection plunger and the screw in the injection cylinder. In the injection device, an axial end surface of the injection plunger is brought into close contact with an inner surface of the injection cylinder at a forward end position thereof, and is set in advance when the injection plunger is driven forward. Both of the forward drive force and forward speed of the injection plunger are set in advance at the set switching position. Screw-in plunger-type injection apparatus according to claim plunger drive control device for adjusting the provision so that the limit value or less were. 2. A tip side inner surface of the injection cylinder is a tapered inner surface, and a tip end surface of the injection plunger is a tapered end surface corresponding to the tapered inner surface of the injection cylinder. 2. A screw-in plunger type injection device according to claim 1, wherein the injection plunger is advanced so that the tapered end face comes into close contact with the tapered inner surface of the injection cylinder. . 3. A tip end surface of the screw has a shape corresponding to a tip end side inner surface of the injection cylinder.
3. The screw-in plunger type injection device according to claim 1, wherein a gap is interposed between a tip end surface of the screw and a tip end side inner surface of the injection cylinder at a forward end position of the screw. 4. The screw is movable relative to the injection plunger in the axial direction, and the screw is held in a state in which an axial end surface of the injection plunger is in contact with an inner surface of the injection cylinder. By retreating, a reduced storage portion is formed on the tip side of the injection screw in the injection cylinder, and a screw driving means for driving the screw in the axial direction with respect to the injection plunger is provided. The molding resin material fed into and stored in the reduced storage section by the rotation of the screw, and is injected by the axial advance operation of the screw. A screw-in plunger-type injection device according to item 1. 5. A cylindrical injection plunger is inserted into the injection cylinder so as to be able to advance and retreat in the axial direction, and a screw is inserted into the injection plunger. A screw-in plunger in which a resin material is fed into a storage portion on the tip side of the injection plunger, and a molding resin material in the storage portion is injected by advancing the injection plunger and the screw in the injection cylinder. In the injection-type injection device, when the injection plunger is driven forward, when the injection plunger reaches a preset switching position, both the forward driving force and the forward speed of the injection plunger are set in advance. By adjusting the injection plunger at a low force and a low speed by adjusting the injection plunger to the limit value or less, Injection-operation control method in a screw-in plunger-type injection device for causing axial distal end surface of the plunger tightly abutting against the inner surface of the injection cylinder.