JP3471658B2 - Injection device and injection molding method using the injection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric injection device for rotating and moving a screw by a servomotor and an injection molding method using the electric injection device, and more particularly, to highly accurately and stably control the back pressure of the injection screw. The present invention relates to an injection device having a simple structure capable of performing the above and an injection molding method using the injection device.

[0002]

BACKGROUND ART Conventionally, in the molding of resin products and the like,
A screw is arranged inside the heating cylinder, and based on the rotation of the screw around the axis and the movement in the axial direction, the injection material introduced into the heating cylinder is fluidized and measured, and further the heating cylinder is heated. An in-line screw type injection molding machine is widely used in which a predetermined mold is injection-filled through the tip nozzle.

By the way, as a screw driving device in such an injection molding machine, conventionally, a driving means for rotating the screw around an axis and a driving means for moving the screw in the axial direction are separately provided. However, in recent years, in Japanese Patent Laid-Open No. 59-2827, etc., a first power transmission mechanism that exerts a rotational driving force of a single electric motor as a rotational force about the axis of a screw, and a feed mechanism. A second power transmission mechanism that exerts a screw action as a moving force in the axial direction of the screw, and the first and second power transmission mechanisms on the power transmission paths in the first and second power transmission mechanisms interrupt the transmission of the driving force. A screw drive device having a structure in which each second clutch means is provided has been proposed. According to the screw drive device having such a structure, by selectively actuating the first and second clutch means, the rotation drive around the axis of the screw and the axial movement drive can be selectively performed by one electric motor. Therefore, it is possible to reduce the size and cost of the control device, and by extension, the screw drive device, by making the operation control system of the screw into one system. is there.

In such a screw driving device, by rotating the screw around the axis,
The injection material supplied to the inside of the heating cylinder is plasticized while being guided and stored forward, and the injection material is weighed based on the retracted amount of the injection screw retracted by the pressure of the injection material stored forward, so-called. In the plasticizing / measuring process, a mechanical brake capable of exerting an appropriate braking force on the power transmission path of the second power transmission mechanism that exerts the driving force of the electric motor as a moving force in the axial direction of the screw by the action of the feed screw. A back pressure is obtained by providing a means to provide resistance to the axial movement of the screw. However, since such a mechanical braking means obtains a braking force by a dynamic frictional force due to sliding or the like, it is difficult to achieve highly accurate control or stabilization of the back pressure in the screw. Therefore, as described above, in the conventional screw drive device, the back pressure of the screw during injection molding tends to be unstable, the injection amount becomes unstable, and air bubbles are mixed in the injection material. As a result, defective products such as burns and chips are likely to occur in the molded product, and a stable molding operation cannot be expected, which is a serious problem.

Japanese Patent Laid-Open No. 4-238015 discloses a hydraulic cylinder mechanism for applying back pressure to the screw, which is separate from the screw rotation and movement mechanism by the electric motor. . That is, by adopting the hydraulic cylinder mechanism for back pressure in addition to the electric motor for driving the screw, it becomes possible to stably apply highly accurate back pressure to the screw with the small hydraulic cylinder mechanism. Of.

However, when such a hydraulic cylinder mechanism is provided, a special hydraulic line and its control system are required, and the structure is inevitably complicated. Therefore, depending on the type of injection device, The realization of a simpler back pressure control mechanism was eagerly awaited.

[0007]

The present invention has been made in view of the circumstances as described above, and the problem to be solved is that the driving force of one electric motor is rotated around the shaft with respect to the screw. In the injection device equipped with the driving force transmission system that can selectively exert the rotational driving force and the axial movement driving force, the screw back pressure control accuracy can be improved by a simple structure. An object is to provide an injection device and an injection molding method using the same.

[0008]

In order to solve such a problem, in the present invention, (a) a first servomotor, and (b)
A first power transmission mechanism that transmits the rotational driving force of the first servomotor to a screw inserted in a heating cylinder to allow the screw to rotate about the axis while allowing axial movement with respect to the heating cylinder. And (c) first clutch means that is provided on the power transmission path of the first power transmission mechanism and that interrupts transmission of the rotational driving force,
(D) The rotation driving force of the first servomotor is transmitted by a feed screw mechanism to a supporting member that supports the screw so as to be rotatable about its axis and relatively immovable in the axial direction, and the supporting member is provided. A second power transmission mechanism for moving the screw in the axial direction via the second power transmission mechanism, and (e) a second power transmission mechanism provided on a power transmission path in the second power transmission mechanism for intermittently transmitting the rotational driving force. In the injection device including a screw driving device configured to include the clutch means of (1), an output shaft that is always interlocked with the screw shaft of the feed screw mechanism, and has a capacity larger than that of the first servo motor. With a small second servo motor,
By applying the rotational driving force of the second servomotor to the screw by the feed screw mechanism, a back pressure is applied to the screw and the first and second servos are also applied.
Each position sensor that detects the screw position is attached to the Bo-Motor.
Be provided and detected by the second servo motor
The position data of the screw
Based on the position signal of the screw that will be detected by a first servo motor, that it has to manage the axial position of such a screw, characterized.

In such an injection device having the structure according to the present invention, the back pressure of the screw is directly exerted by the rotational driving force of the second servomotor having a small capacity, so that the back pressure of the screw is reduced. It is possible to control with high accuracy and stability. Further, as is clear from the fact that the back pressure is about 1/10 of the injection pressure under general injection conditions, the second servo motor is sufficiently smaller than the first servo motor. Since a large capacity is adopted, it becomes possible to provide the target injection device with an inexpensive and simple structure, and in comparison with the case where the screw back pressure is controlled by the first servomotor. The back pressure can be controlled easily with high accuracy. In addition, since the output of the single first servomotor is used as the rotation driving force and the injection driving force for the screw, when the motor for the rotation driving force and the motor for the injection driving force are provided separately. It is also possible to reduce the total motor capacity in comparison with. It should be noted that the output of the second servomotor can be used supplementarily as the injection driving force for the screw.

Moreover, the output shaft of the second servo motor is
Since the screw is always interlocked with the axial movement of the screw via the feed screw mechanism, the relative position of the output shaft of the first servomotor to the screw is changed by the first and second clutch means. Also, by using the detection signal from the first servo motor as a reference, the position of this screw can be easily grasped as an absolute position,
Therefore, the position control of the screw in the injection process or the like can be stably and highly accurately performed.

Further, in the injection device having the structure according to the present invention, a one-way clutch is adopted as the first clutch means, and the first power transmission mechanism applies a rotational driving force to the screw through the first power transmission mechanism. and rotational direction of the output shaft of one servo motor, and a rotational direction of the output shaft of said first servo motor for exerting an axial drive force to the screw through the second power transmission mechanism, and to each other opposite The above configuration can be suitably adopted. If such a configuration is adopted, the first clutch means can be advantageously realized with a simple structure.

Further, in the injection apparatus having the structure according to the present invention, more preferably, the first servo motor employs an increment type rotary encoder, while the second servo motor employs an absolute type rotary encoder. A configuration that employs an encoder can be employed. If such a configuration is adopted, the absolute position of the screw can always be stably detected by the second servo motor, and based on the position signal of the screw detected by the second servo motor, It is also possible to detect the screw position with high accuracy by the first servomotor by appropriately rewriting the data of the rotary encoder of the first servomotor while the second clutch means is connected.

In order to solve the above-mentioned problems,
The present invention uses the injection device having the structure as described above,
When performing injection molding of a predetermined molding material, the first clutch means is connected and the second clutch means is disengaged to transmit the rotational driving force of the first servomotor to the screw. In the plasticizing / measuring step of rotating the screw in the cylinder to plasticize and measure the molding material, the rotational driving force of the second servomotor is exerted in the axial direction of the screw. While applying back pressure, the first clutch means is in a disengaged state and the second clutch means is in a connected state so that the rotational driving force of the first servomotor is exerted on the support member. In the injection step of injecting the measured molding material from the heating cylinder by driving the screw in the axial direction,
An injection molding method for performing position management of the screw based on a screw position signal detected by the first servo motor, which is rewritten in advance with position data of the screw detected by the second servo motor. Is also a feature.

According to such a method of the present invention, the position of the screw is controlled by utilizing the position detection signal of the first servomotor which exerts the axial driving force directly on the screw in the injection process or the like. Therefore, it is possible to control the screw position with higher accuracy.

In the method of the present invention, preferably, after the injection step or the plasticizing step, when the screw is retracted, the rotational driving force of the second servomotor is applied by the feed screw mechanism to the screw. To drive the screw backward. Thus, for example, even when a one-way clutch is used as the first clutch means, the backward drive of the screw can be quickly performed with a simple structure.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, in order to more specifically clarify the present invention, one embodiment of the present invention will be described in detail with reference to the drawings.

First, FIGS. 1 and 2 show an embodiment of an injection apparatus having a structure according to the present invention. In this figure, reference numerals 10 and 11 denote main frames of the injection molding machine, which are spaced apart from each other and are opposed to each other in a fixed relative position. Then, the body frames 10, 11
Although not shown, as is well known, is supported by a slide base laid on the bed of the injection molding machine so as to be integrally movable with respect to the mold clamping device (not shown) in the approaching and separating directions. There is.

A heating cylinder 14 having a nozzle 12 at its tip (left end in FIG. 1) is fixedly attached to one of the main body frames 10 (left in FIG. 1). ing. The heating cylinder 14
Is heated to an appropriate temperature by a known heater means. Although not shown, the body frame 10 is provided with a material supply passage that penetrates the wall of the heating cylinder 14 and opens to the upper surface, as is well known, and a hopper (Fig. (Not shown) is attached. Then, the injection material is supplied into the heating cylinder 14 from the inside of the hopper through the material supply passage.

Further, an injection screw 18 is inserted and arranged inside the heating cylinder 14. The injection screw 18 has bearings 20, 2 at the base end (right side in FIG. 1) protruding from the heating cylinder 14.
2 is attached to the sub-frame 30 disposed between the facing surfaces of the pair of main body frames 10 and 11 via
The subframe 30 supports the shaft so as to be rotatable about its axis and immovable in the axial direction. The subframe 30 is movably supported between the facing surfaces of the body frames 10 and 11 in a direction parallel to the moving direction of the body frames 10 and 11. That is, the one main body frame 10 side or the other main body frame 11 in the facing direction of the main body frames 10 and 11 of the sub-frame 30.
By the movement to the side, the injection screw 18 is displaced in the axial direction with respect to the heating cylinder 14. If necessary, the body frame 10
Etc., a guide mechanism for guiding the subframe 30 in the moving direction is provided.

On the other hand, the body frame 11 is provided with a transmission sleeve 24 having an axially extending spline groove on its inner surface.
The bearing 26 is supported so as to be rotatable about the central axis and immovable in the axial direction. A transmission shaft 28, which extends from the rear end portion (the right end portion in FIG. 1) of the injection screw 18 and is fixedly installed, is inserted into the transmission sleeve 24, and the outer periphery of the transmission shaft 28. An axially extending fitting protrusion provided on the surface is spline-fitted in the spline groove of the transmission sleeve 24. As a result, the injection screw 18 is connected to the transmission sleeve 24 so as to be relatively movable in the axial direction and non-rotatably in the circumferential direction.

A toothed pulley 32 for rotational driving is fixed to the transmission sleeve 24 at the axial end opposite to the side connected to the injection screw 18. The first servomotor 34 is fixedly supported by the main body frame 11, and the first toothed pulley 38 attached to the output shaft 36 of the first servomotor 34 and the transmission sleeve 24. Between the fixed toothed pulley 32,
The first toothed belt 40 is stretched around. Further, the output shaft 36 of the first servomotor 34 and the first toothed pulley 3
The one-way clutch 42 is interposed between the eight shafts 8 so that the rotation of the output shaft 36 is allowed only in one direction. The one-way clutch 42, such as a well-known cam clutch, operates in the same manner as when the first toothed pulley 38 is fixed to the output shaft 36 when transmitting the driving force in one direction, and drives in the opposite direction. At the time of transmission, a device that can exhibit the same operation as that of the first toothed pulley 38 that is freely rotatable relative to the output shaft 36 is adopted.

In the present embodiment, the one-way clutch 42 limits the rotational driving direction of the injection screw 18 driven by the first servomotor 34 to only one direction, so that the injection screw 18 is rotated. In the heating cylinder 14, the injection material can be allowed only in the forward direction in which the injection material is fed forward, and its reversal is prevented. Further, as is apparent from the above description, in the present embodiment, the first power transmission including the output shaft 36, the first toothed pulley 38, the first toothed belt 40, and the toothed pulley 32 is included. The mechanism is configured.

Further, the first servomotor 3 is disposed on the power transmission path of the first power transmission mechanism.
By the one-way clutch 42 that transmits the rotational driving force of No. 4 to the injection screw 18 only in one direction,
A first clutch means is configured.

On the other hand, the body frames 10 and 11 have ball screw shafts 4 provided with ball screw grooves on their outer peripheral surfaces on both sides sandwiching the heating cylinder 14, respectively.
4 are arranged so as to extend in parallel to each other across the facing surfaces of the body frames 10 and 11. The two ball screw shafts 44, 44 are respectively attached to the body frame 1 by a plurality of bearings 46.
It is supported by 0 and 11 so as to be immovable in the axial direction and rotatable about the central axis. Then, the ball screw nuts 56, 56 fixedly attached to the sub-frame 30 are attached to the ball screw shafts 44, 44.
They are screwed together. The ball screw shafts 44, 44 project through the main body frame 11 at the axial end portions on the main body frame 11 side, and are axially driven with respect to the projected axial end portions, respectively. The toothed pulley 48 for is fixed.

Further, a second toothed pulley 50 is attached to the output shaft 36 of the first servomotor 34 independently of the first toothed pulley 38. A second toothed belt 52 is stretched between the pulley 50 and the toothed pulley 48 for driving in the axial direction. Furthermore, the output shaft 36 of the first servomotor 34 and the second toothed pulley 5
An electromagnetic clutch 54 as a second clutch means is interposed between 0, and by switching the electromagnetic clutch 54, the toothed pulley 48 is provided on the output shaft 36 of the first servomotor 34. The free disconnection state in which relative movement around the central axis is allowed and the connection state in which relative movement around the central axis is blocked and fixed are appropriately switched. When the electromagnetic clutch 54 is disengaged, the ball screw shaft 44 is allowed to freely rotate regardless of the state of the first servomotor 34, while the electromagnetic clutch 54 is engaged. Below, the rotational driving force of the first servomotor 34 is
Ball screw shafts 44, 4 via the second toothed belt 52.
4 is transmitted.

As a result, when the electromagnetic clutch 54 is connected, the rotational driving force of the first servomotor 34 is
The sub-frame is transmitted to the ball screw shafts 44, 44, and based on the screw feed action of the screw leads of the ball screw mechanism as the feed screw mechanism including the ball screw shafts 44, 44 and the ball screw nuts 56, 56. 30 is displaced in the direction in which the body frames 10 and 11 face each other, and by extension, the injection screw 18 causes the heating cylinder 14 to move.
Therefore, they are moved relative to each other in the axial direction. As is apparent from the above description, in the present embodiment, the ball screw shafts 44, 44 and the ball screw nut 5 are provided.
The second power transmission mechanism is constituted by 6, 56, the toothed pulleys 48, 50 and the toothed belt 52.

Furthermore, a second servo motor 60 is fixedly mounted on the body frame 11. The toothed pulley 64 fixed to the output shaft 62 of the second servomotor 60 and the toothed pulleys 48, 48 attached to the ball screw shafts 44, 44 straddle the second toothed pulley 64, The toothed belt 52 of the second toothed belt 5
2, the rotational drive force of the toothed pulley 64 is exerted on the ball screw shafts 44, 44 as the rotational drive force. Particularly, on the transmission path of the driving force from the output shaft 62 of the second servo motor 60 to the ball screw shafts 44, 44, there is no clutch means or the like for permitting relative movement, so that the second servo motor The output shaft 62 of 60 is kept connected to the ball screw shafts 44, 44 at all times.

In short, the axial position of the injection screw 18 directly corresponds to the rotation amount (rotational position) of the ball screw shafts 44, 44, and further, the rotation of the ball screw shafts 44, 44. The rotation amount (rotational position) of the output shaft 62 of the second servomotor 60 directly corresponds to the amount (rotational position). Therefore, the output shaft 62 of the second servomotor 60 is The rotational position of the position sensor 68 such as a rotary encoder provided in the second servomotor 60.
The position in the axial direction of the injection screw 18 can be detected by detecting with. Particularly, in the present embodiment, in the second servo motor 60, the position sensor 6
An absolute type rotary encoder is adopted as 8, and the absolute position of the injection screw 18 can be detected. On the other hand, in the first servomotor 34, a deviation from the axial position of the injection screw 18 occurs due to the one-way clutch 42 and the electromagnetic clutch 54. An encoder may be advantageously employed.

Then, the rotational driving force of the first servomotor 34 is transmitted to the injection screw 18 through the first power transmission mechanism including the above-mentioned first toothed pulley 38, first toothed belt 40 and the like. Then, in a state where the injection screw 18 is rotationally driven, the rotational driving force of the second servomotor 60 is transmitted to the injection screw 18 as an axial driving force.
In particular, by exerting the driving force of the second servomotor 60 in the direction in which the injection screw 18 is driven forward, it is effective for the injection screw 18 in the plasticizing / measuring process by the rotation of the injection screw 18. It can exert back pressure.

In addition, in this way, the second servomotor 60
Does not mainly apply the injection driving force to the injection screw 18, but mainly applies the back pressure to the injection screw 18, so that the capacity is sufficiently smaller than that of the first servomotor 34. For example, it is possible to employ one having a capacity of about 1/5 or about 1/10.

3 to 9 are time charts showing specific examples of the operation when the molding operation of the resin material is carried out by the injection device having the above-mentioned structure.
Here, FIGS. 3 to 8 are time charts of injection operation by manual switch operation, and FIG. 9 is a time chart of injection operation by automatic operation. In particular, FIG.
The injection operation (the forward operation of the injection screw 18) from the OFF state of the electromagnetic clutch 54 is shown, and FIG. 4 shows the injection operation from the ON state of the electromagnetic clutch 54. In addition, FIG.
6 shows the screw retracting operation from the OFF state of the electromagnetic clutch 54, and FIG. 6 shows the screw retracting operation from the ON state of the electromagnetic clutch 54. Further, FIG. 7 shows the electromagnetic clutch 5.
4 shows the screw rotation operation (plasticization / metering operation) from the OFF state, and FIG. 8 shows the screw rotation operation from the ON state of the electromagnetic clutch 54.

That is, in the injection device as described above, the operation (driving force) of one first servo motor 34 causes
Injection operation (axial forward movement of the injection screw 18) and screw rotation operation are performed. The switching between these two operations is performed using the electromagnetic clutch 54. Specifically, when the electromagnetic clutch 54 is excited (connected) to allow the driving force of the output shaft 36 of the first servo motor 34 to be transmitted to the injection screw 18, the first servo motor 34 in the reverse direction (one-way clutch 4
The injection operation is carried out by driving in a direction in which the rotational driving force is not transmitted by 2. On the other hand, in the screw rotation operation, the toothed pulley 4 with respect to the output shaft 36 of the first servomotor 34 is not excited (connected) with the electromagnetic clutch 54.
8 is allowed to rotate, the first servomotor 34 is driven in the forward rotation direction to drive the one-way clutch 42.
The injection screw 18 is rotationally driven via the.

When the injection screw 18 is driven by such a mechanism, the electromagnetic clutch has a corresponding relationship between the axial position of the injection screw 18 and the rotational position of the output shaft 36 of the first servomotor 34. 54 and the one-way clutch 42 cause the shift. Therefore, as shown in FIGS. 5 to 9, the position management of the injection screw 18 when the screw is retracted and the screw is rotated is as follows.
The second servo motor 60, whose rotation position always appears in correspondence with the axial position of, is performed based on the output signal of the rotary encoder.

On the other hand, during the injection operation, it is also possible to directly utilize the output signal of the rotary encoder of the second servo motor 60 to manage the axial position of the injection screw 18, as well. In the embodiment, FIGS.
As shown in Fig. 9, before the start of the injection operation,
After the correspondence between the axial position of the injection screw 18 and the rotational position of the output shaft 36 of the first servomotor 34 does not shift, for example, as shown in FIG. 3, the electromagnetic clutch 54 is turned off. At the same timing as switching from the state to the ON state (connection state), the second servo motor 6
The current position of the injection screw 18 is set in the rotary encoder of the first servo motor 34 by writing the position detection data in the rotary encoder of 0 into the data of the rotary encoder of the first servo motor 34. Accordingly, during the subsequent injection operation, the axial position of the injection screw 18 can be directly controlled based on the detection signal from the rotary encoder of the first servomotor 34, and the rotary of the second servomotor 60 can be controlled. Compared with the case of using the detection signal from the encoder, the control accuracy can be further improved.

In the time charts of FIGS. 3 to 9, regarding the operation of the first and second servomotors 34 and 60, the range of the arrow indicates the driving state of the servomotors 34 and 60, and other than that. It is desirable that the control of is a servo lock (position holding control). Further, the delay time for checking when the electromagnetic clutch 54 is switched ON / OFF can be set by using timer setting by software, for example.

Although one embodiment of the present invention has been described in detail above, it is merely an example, and the present invention is
The specific description in such an embodiment is not to be construed as limiting in any way, and may be carried out in a mode in which various changes, modifications and improvements are added based on the knowledge of those skilled in the art. 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.

[0037]

As described above in detail, according to the present invention, the driving force of the first servomotor is utilized to realize the rotation operation and the forward operation of the injection screw with a simple structure. In addition to being able to do, by adding a second servo motor with a capacity sufficiently smaller than the first servo motor, the back pressure to the injection screw is
With a simple structure, it can be applied with high accuracy.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional explanatory view showing an injection device according to a first embodiment of the present invention, which is a combined view of Ia-Ia cross section and Ib-Ib cross section in FIG.

FIG. 2 is a right side view of FIG.

3 is a time chart diagram of an example of an injection operation according to the present invention using the injection device shown in FIG.

FIG. 4 is a time chart of another injection operation example according to the present invention using the injection device shown in FIG.

FIG. 5 is a time chart diagram of a screw retraction operation example according to the present invention using the injection device according to the present invention.

FIG. 6 is a time chart diagram of another example of screw retraction operation according to the present invention using the injection device shown in FIG. 1.

FIG. 7 is a time chart diagram of an example of screw rotation operation according to the present invention using the injection device according to the present invention.

8 is a time chart diagram of another example of screw rotation operation according to the present invention using the injection device shown in FIG. 1. FIG.

FIG. 9 is a time chart diagram of an example of automatic injection operation according to the present invention using the injection device shown in FIG. 1.

[Simple explanation of symbols]

14: Heating cylinder 18: Injection screw 30: Subframe 34: First servo motor 38: First toothed pulley 40: First toothed belt 42: One-way clutch 44: Ball screw shaft 50: Second toothed pulley 52: Second toothed belt 56: Ball screw nut 60: Second servo motor 66: Position sensor 68: Position sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-31221 (JP, A) JP-A-4-348925 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (5)

(57) [Claims] 1. A first servomotor and a rotational driving force of the first servomotor are transmitted to a screw inserted in a heating cylinder to permit axial movement with respect to the heating cylinder while allowing the screw to move in the axial direction. A first power transmission mechanism for rotating the shaft around the shaft, a first clutch means provided on the power transmission path of the first power transmission mechanism for interrupting the transmission of the rotational driving force, and the screw. With respect to a supporting member that is rotatable around and is supported so as to be relatively immovable in the axial direction, the rotational driving force of the first servomotor is transmitted by a feed screw mechanism, and via the supporting member,
A second power transmission mechanism that moves the screw in the axial direction; and a second clutch means that is provided on a power transmission path in the second power transmission mechanism and that interrupts transmission of the rotational driving force. In the injection device including the screw drive device configured as described above, a second servo motor having a smaller capacity than the first servo motor, which includes an output shaft that is always interlocked with the screw shaft of the feed screw mechanism, is provided. By providing the rotational driving force of the second servomotor to the screw by the feed screw mechanism, a back pressure is applied to the screw and the screw positions are applied to the first and second servomotors.
The position of the screw detected by the second servomotor.
To the first servomotor rewritten in advance by
Thus based on the position signal of the screw that will be detected, or
Injection apparatus being characterized in that so as to manage the axial position of the mowing screw. 2. A one-way clutch is adopted as the first clutch means, and a rotation direction of an output shaft of the first servomotor for exerting a rotational driving force on the screw through the first power transmission mechanism, injection apparatus according to the rotational direction of the output shaft of the second said first servo motor for exerting an axial drive force to the screw through the power transmission mechanism, to claim 1 in which the mutually opposite directions. 3. The first servo motor employs an increment type rotary encoder, while the second servo motor employs an absolute type rotary encoder.
The injection device described in 1. 4. When performing injection molding of a predetermined molding material using the injection device according to any one of claims 1 to 3, the first clutch means is brought into a connected state and the second clutch means is connected. Plasticizing / measuring plasticizing and measuring the molding material by rotating the screw in the cylinder by transmitting the rotational driving force of the first servomotor to the screw in a disengaged state of the clutch means. In the step, the rotational driving force of the second servo motor is exerted in the axial direction of the screw to exert a back pressure, while the first clutch means is disengaged,
With the second clutch means in the connected state, the rotational driving force of the first servomotor is exerted on the support member to drive the screw in the axial direction, thereby injecting the measured molding material from the heating cylinder. In the injection step, the position control of the screw is performed based on the screw position signal detected by the first servo motor, which is rewritten in advance with the position data of the screw detected by the second servo motor. An injection molding method characterized by: 5. The method according to claim 4, wherein when the screw is moved backward after the injection step, the rotational driving force of the second servomotor is exerted on the screw by the feed screw mechanism to drive the screw backward. The injection molding method described.