JP5144822B1 - Injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection apparatus having a structure that reduces the cost of the apparatus and suppresses the power consumption by performing the operation of rotating the screw and the operation of moving the screw forward by one driving means.
A screw 3 and a driving means M are connected by a shaft coupling 2 that performs a predetermined clutch operation, and when the driving means M rotates a rotating shaft 5 in the forward direction, the rotational force is transmitted to the screw 3 to be melted. Alternatively, when the mixed molding material is supplied to the injection chamber 4 and the driving means M rotates the rotary shaft 5 in the reverse direction, the rotational force is not transmitted to the screw 3 and the screw 3 moves forward or backward. The flow path 4a to the injection chamber 4 is closed to prevent backflow of the molten or mixed molding material.
[Selection] Figure 2

Description

  The present invention plasticizes, melts or mixes a molding material in a cylinder with a screw and supplies the molding material in a molten state or a mixed state separately to an injection cylinder via a flow path, and a plunger in the injection cylinder. An injection apparatus comprising a backflow prevention mechanism for preventing a molten or mixed molding material from flowing backward from an injection chamber in an injection apparatus for injecting and filling molding material stored in an injection chamber into a mold. About.

  Injection molding is a method in which a plasticized molten or mixed molding material is injection-filled into a mold apparatus and molded, and is suitable for mass production of products having complicated shapes. For example, injection molding using a thermoplastic resin as a molding material is a method in which injection pressure is applied to a resin melted by shearing heat generated by plasticization or heat from a heater, the mold is pressed into a mold, and then cooled and molded. Suitable for mass production of complex shaped products. In general, injection molding of thermoplastic resin is performed in the order of mold closing, mold clamping, injection, holding pressure, cooling, mold opening, and removal of the molded product. Produce. The injection apparatus is an apparatus that plasticizes a resin material supplied from a hopper into a molten state by a heating cylinder and sends the resin material from a nozzle in an injection chamber to a mold apparatus. The pre-plastic injection device has an advantage that the plasticizing ability can be increased because the resin material can be plasticized by the pre-plastic heating cylinder (plasticizing cylinder) even during the injection. In addition, for injection molding, liquid resin injection molding (LIM) using thermosetting resin as molding material, or molding material mixed with binder such as resin and metal powder, metal powder is injected in the same way as resin. There are injection moldings using various molding materials such as metal injection molding (MIM) which can be injection-molded by using an apparatus (such as a pre-plastic injection device or a liquid resin injection device).

  From here, explanation will be made by taking injection molding of a thermoplastic resin as a representative example. A screw pre-plastic injection device can uniformly plasticize a resin material by a kneading action of a plasticizing screw (hereinafter simply referred to as a screw), and can supply an accurate amount of resin to an injection chamber by rotating a screw. There are advantages. These pre-plastic injection devices are provided with a backflow prevention mechanism in order to prevent the plasticized resin from flowing back from the injection chamber. As the backflow prevention mechanism, for example, a mechanism that closes the flow path by a check valve as in Patent Document 1 and maintains the state thereof, or a flow path to the injection chamber at the screw tip as in Patent Document 2 is blocked. However, there is a mechanism for maintaining the state. In the switching valve system described in Patent Document 1, the apparatus configuration in the flow path of the molten resin material becomes complicated, and there is a problem that it is difficult to take the timing of the linking operation between the check valve and the screw.

  Patent Document 2 relates to a screw pre-pull type injection device, which describes a backflow prevention mechanism that closes the flow path to the injection chamber at the tip end of the screw and maintains the state thereof. During the process, the rotating means is driven at a position where the screw is retracted to allow the molten material to flow from the plasticizing chamber side opening through the flow path into the injection chamber, and during the injection process, The driving device is operated in a state where the rotating means is stopped, and the screw is advanced to close the plasticizing chamber side opening. In this embodiment, the hydraulic pressure on the forward side of the hydraulic cylinder 8 is described. When the pressure oil is supplied from the supply port 16, the screw 3 moves forward and the tip thereof is pressed against the front wall surface 4a of the plasticizing chamber, the convex portion and the concave portion are brought into close contact with each other, and the flow path 4a is closed. The flow path 4a is blocked by the advance of the screw 3. In this state, the injection plunger 21 advances on the injection chamber 20 side to inject the accumulated molten material, and at this time, the molten material tries to flow back from the injection chamber 20 to the plasticizing chamber 4 through the flow path 4a. The screw 3 pressed by 9 resists this injection flow against the injection pressure, and then rotates the screw 3 and simultaneously releases the hydraulic pressure at the hydraulic pressure supply port 16 to resume the plasticizing and metering process for melting the material. The screw 3 is retracted by the pressure of the molten resin material, the contact between the concave portion and the convex portion is released, and the flow path is opened "(see FIG. 7). That is, Patent Document 2 is a system in which the screw itself functions as a check valve, and prevents the backflow of the molten resin material to the plasticizing chamber during the injection process without using a ball valve or a check valve.

JP-A-9-136334 Japanese Patent Publication No. 5-037810 Japanese Patent No. 2782419

  By the way, the backflow prevention mechanism in the pre-plastic injection device of the above-mentioned Patent Document 1 is different in the drive means for the means for extruding the molten resin material into the injection chamber and the drive means for the check valve. Further, the driving means for rotating the screw of Patent Document 2 and the driving means for advancing the screw as a backflow stop are separate driving means. This is because it is difficult to perform the operation of rotating the screw and the operation of moving the screw forward with a single driving means. And as the drive means, dedicated drive means by hydraulic pressure, pneumatic pressure, and electric power are used for rotation and forward use, respectively, and since the dedicated drive means is used, the apparatus cost increases correspondingly, Energy consumption is also increased because energy is consumed while the flow path is closed. There is also an injection device configured to prevent the flow path from being backflowed by retracting the screw (Patent Document 3), but has the same problem as described above.

  Accordingly, an object of the present invention is to provide an injection apparatus having a structure that reduces the cost of the apparatus and suppresses the power consumption by performing an operation of rotating the screw and an operation of moving the screw forward by a single driving means.

The injection device of the present invention plasticizes, melts or mixes the molding material in the cylinder with a screw, and supplies the molten or mixed molding material into a separately provided injection cylinder via a flow path, and injects it with a plunger. In an injection apparatus for injecting and filling a molding material in a molten state or a mixed state stored in an injection chamber in a cylinder,
The screw and the drive means are connected by a shaft coupling that performs a predetermined clutch operation, and the shaft coupling includes at least a clutch, a cam, and a cam follower,
When the driving means rotates the rotating shaft in the forward direction, the rotational force is transmitted to the screw to supply a molding material in a molten state or a mixed state to the injection chamber ,
When the driving means reversely rotates the rotating shaft, the rotational force is transmitted to either the cam or the cam follower, and the screw moves forward or backward by the relative displacement of the cam and the cam follower to move to the injection chamber. The flow path is closed to prevent backflow of the molten or mixed molding material. Here, examples of the connection between the driving means and the rotating shaft include a spline connection and a joint that expands and contracts only in the forward and backward directions.

According to the present invention, by providing a mechanism in which a screw and a driving unit are connected by a shaft coupling that performs a clutch operation, a molding material in a molten state or a mixed state (for example, the molding material is thermoplastic by one driving unit). If it is resin, the fixed quantity supply of molten resin material) can be performed smoothly. When the driving means rotates the rotating shaft in the forward direction, the rotating force is transmitted to the screw, and the molten or mixed molding material is supplied to the injection chamber. When the driving means rotates the rotating shaft in the reverse direction, the rotating force is supplied. Does not transmit to the screw, but the screw moves forward or backward to block the flow path to the injection chamber and perform backflow prevention by a single drive means. According to the present invention, since the shaft coupling is a mechanical clutch and the screw does not rotate when the flow path to the injection chamber is closed, the configuration is more robust and power-saving than the electromagnetic or electronic control type. Become.

The present invention, in the shaft coupling is by the rotary shaft coaxially, the clutch, the cam and the cam follower are at least provided,
When the rotary shaft is rotated forward, the rotational force is not transmitted to the cam or the cam follower by the clutch, but the rotational force is transmitted to the screw to inject the molten or mixed molding material. Supply to the room,
When the rotary shaft is rotated in the reverse direction, the rotational force is not transmitted to the screw by the clutch, but the rotational force is transmitted to either the cam or the cam follower. configuration displaced by and closes the flow path to the injection chamber the screw moves forward or backward to the reverse flow stopping of the molding material in a molten state or a mixed state are preferred.

  According to the present invention, by using the cam and the cam follower (cam follower) for the backflow prevention operation by the screw, the position of the cam with respect to the cam follower (or the position of the cam follower with respect to the cam) is simply moved to a predetermined position. Therefore, the driving force of the driving means during the backflow prevention becomes unnecessary.

The present invention, the clutch, the only positive rotation of the rotary force of the rotary shaft and the one-way clutch as screw clutch. Used to transmitted to the screw, the only rotational force of the reverse rotation of the rotating shaft cam or consists of a one-way clutch as a cam clutch. Used to transfer either one of the cam follower,
When the rotating shaft is rotated forward, the rotational force is transmitted to the screw, and the screw rotates to supply the molten molding material to the injection chamber,
When the rotating shaft is rotated in the reverse direction, the rotational force is not transmitted to the screw, and each time the rotating shaft is rotated in the reverse direction at a predetermined angle, the screw is moved forward or backward to close the flow path of the injection chamber and back flow. A configuration that switches between a state of stopping and a state of releasing only the pressing force for the backflow prevention or a state of opening the flow path by retreating or advancing in the opposite direction to the case of backwashing the screw. Is preferred.

  According to the present invention, the flow path is blocked and opened by the screw, thereby realizing an accurate and smooth operation by forward rotation and reverse rotation by a single drive means. That is, it is possible to smoothly switch between the operation of rotating the screw and the operation of moving forward and backward without rotating the screw by forward and reverse rotation from the driving means.

The present invention, when the said screw is a forward or backward to close the opening of the channel, the configuration has internal first biasing member for generating a pressing force required to reverse flow stopping preferred.

  According to the present invention, when the screw is moved forward to prevent the backflow, the molding material in the molten state or the mixed state in the injection chamber that receives the injection filling pressure and backflows (for example, the molding material is a thermoplastic resin). If necessary, the pressure force required for backflow prevention, which is greater than that of the molten resin material), is applied by the first biasing member. Therefore, even if the total length of the screw is extended due to thermal expansion, it is necessary for backflow prevention. Therefore, it is possible to prevent the screw or the like from being damaged without causing the excessive pressing force to be excessive, and even when the screw contracts due to thermal contraction, the pressing force necessary for the backflow prevention can be generated without shortage. The first urging member may be disposed at the rear end portion of the shaft coupling that performs a predetermined clutch operation, or between the shaft coupling and the screw, or at a place that exhibits the same effect as above.

In the present invention, it is preferable that the second urging member for always bringing the cam follower into contact with the cam surface of the cam is provided .

According to the present invention, particularly when an end face cam or the like is used for the cam, the cam and the cam follower are always brought into contact with each other by the second urging member, thereby canceling the backflow prevention of the cam and the cam follower. In this position, the pressing force required for backflow prevention is released, and the screw can be forcibly retracted to the reference position.
Here, as this invention, it is preferable that the said screw is a plasticizing screw and the said cylinder which inserts the said screw is a plasticizing cylinder. Moreover, it is preferable that the said screw is a mixing screw and the said cylinder which inserts the said screw is a mixing cylinder.

  According to the present invention, since the backflow prevention mechanism is configured to be connected to the driving means via the shaft coupling that performs a predetermined clutch operation, the operation of rotating the screw and the operation of moving the screw forward or backward are performed in one. It can be performed by a drive means, and the shaft coupling is combined with a mechanical one-way clutch, so that the operation of closing or opening the flow path to the injection chamber without rotating the screw is performed as one drive. It can be performed accurately and smoothly by the means, and further, an energy saving configuration is obtained by moving the screw forward or backward by a cam mechanism.

It is sectional drawing which shows the state during plasticization (or mixing) of the injection device of the 1st Embodiment of this invention. It is sectional drawing which shows the backflow prevention state of the injection device of the 1st Embodiment of this invention. In the injection device of the 1st embodiment of the present invention, it is a sectional view showing the state where the pressing force applied to the screw at the time of backflow prevention was released, but the screw is still in the backflow prevention position. It is sectional drawing which shows another attachment form of the plasticization reaction force receiver in the injection device of the 1st Embodiment of this invention. It is sectional drawing which shows the injection apparatus of the 2nd Embodiment of this invention. It is sectional drawing which shows the whole structure of the injection apparatus of this invention. It is sectional drawing which shows the conventional injection apparatus.

  Specific embodiments to which the present invention is applied will be described below with reference to the drawings.

(First embodiment)
FIG. 6 is a cross-sectional view of the overall configuration of the injection apparatus 1 according to the first embodiment of the present invention. In the present embodiment, the present invention is applied to a screw pre-pull type injection device 1, and a plasticizing chamber 4 in a plasticizing cylinder 44 containing a screw 3 and an injection chamber in an injection cylinder 22 containing an injection plunger 21. 20 and the molten resin material plasticized and kneaded in the plasticizing chamber 4 are accumulated in the injection chamber 20 through the flow path 4a. The opening of the flow path 4a on the plasticizing chamber 4 side is open on the axis of the screw 3 at the tip of the plasticizing chamber. And the front-end | tip of the screw 3 is pressed by the flow path 4a of the front wall surface of the plasticization chamber 4, and obstruct | occludes the flow path 4a. In a state where the flow path 4a is closed by the advance of the screw 3, the injection plunger 21 advances on the injection chamber 20 side and the accumulated molten resin material is injected. At this time, the molten resin material tries to flow backward from the injection chamber 20 to the plasticizing chamber 4 through the flow path 4 a, but the backflow prevention mechanism 2 (shaft coupling that performs a predetermined clutch operation) of the present invention is arranged in the casing 11. The reverse flow is stopped while controlling the operation of the screw 3.

  FIG. 1 to FIG. 3 are cross-sectional views for explaining the drive mechanism of the screw 3 in the plasticizing chamber 4 of the screw preplar type injection device 1 of the present embodiment. This embodiment is coaxial with the rotating shaft 5 to which the driving means M is connected, and is provided with clutches 6 and 9 and a cam mechanism 8 (cam 8 a and cam follower 8 b), and a check shaft connected to the screw 3. 7 is arranged. That is, the check shaft 7 grips the rear end of the screw 3, the rotary shaft 5 grips the rear end of the check shaft 7 via the screw side clutch 9, and the rotary shaft 5 is connected to the driving means M to rotate. A cam side clutch 6 and a cam mechanism 8 (cam 8 a and cam follower 8 b) are disposed on the outer periphery of the shaft 5, and a screw side clutch 9 is disposed on the outer periphery of the check shaft 7. Examples of the driving means M include various motors such as an electric motor, a hydraulic motor, and a pneumatic motor. Then, the single drive means M performs the rotation, forward movement and backward movement of the screw 3. In this embodiment, the connection between the driving means M and the rotating shaft 5 transmits the rotation of the driving means M to the rotating shaft 5 by spline coupling or the like, but the rotating shaft 5 can be advanced and retracted with respect to the driving means M. It has become.

  The clutches 6 and 9 are configured such that the cam side clutch 6 disposed on the cam mechanism 8 side and the screw side clutch 9 disposed on the screw 3 side are combined so that the respective rotation permissible directions are opposite to each other. Yes. The two clutches 6 and 9 are allowed to rotate only in one direction, and a one-way clutch that transmits the rotation only in one direction is combined and used so that the directions in which rotation is allowed are reversed. The one-way clutch has, for example, an outer ring and an inner ring, and if the rotation direction is an allowable direction with respect to one of the rotation movements, the other is also provided and the rotation movement is transmitted. If the direction is a non-permissible direction, no rotational motion is transmitted to the other.

  The flange part of the front end of the rotating shaft 5 and the outer ring 9a of the screw side clutch 9 are fastened, and the shaft part of the rotating shaft 5 and the inner ring 6b of the cam side clutch 6 are fastened. Further, the shaft portion at the rear portion of the check shaft 7 and the inner ring 9 b of the screw side clutch 9 are fastened. And the base part of the screw 3 and the front-end | tip part of the non-return shaft 7 are connected relatively non-rotatably. The screw 3 and the check shaft 7 may be spline connected or completely coupled. The screw 3 and the inner ring 9b of the screw side clutch 9 may be directly fastened. The clutches 6 and 9 may perform such operations with a meshing clutch or a friction clutch.

  The cam mechanism 8 includes a cam 8a and a cam follower 8b that follows the cam 8a. The cylindrical cam 8 a is fastened to the outer ring 6 a of the cam side clutch 6 and is connected to the rotating shaft 5 via the cam side clutch 6. The cam follower 8b is arranged in a non-rotating state as a bearing base 15 in which a roller bearing 15 is arranged on the circumference. Further, the cam 8a and the cam follower 8b are arranged so as to freely advance and retract in the axial direction of the rotary shaft 5. In the present embodiment, a cylindrical end face cam is adopted as the cam 8a, and the waveform of the joint surface between the end face cam 8a and the cam follower 8b, that is, the cam face of the cylindrical end face cam 8a is formed on the circumference. Are provided at a predetermined interval (formed by a continuous waveform of a concave portion and a convex portion). For this reason, in the present embodiment, the end face cam 8a itself is moved relative to the cam follower 8b by rotating the end face cam 8a with respect to the cam follower 8b and utilizing the height difference Xd between the concave and convex portions of the cam face. The rotary shaft 5 is moved forward and backward by approaching or separating. Thus, when the concave portion of the cam surface and the cam follower 8b come into contact with each other, the screw 3 moves backward to open the flow path 4a of the plasticizing chamber 4, and when the convex portion of the cam surface and the cam follower 8a come into contact with each other, the screw 3 As a result, the flow path 4a of the plasticizing chamber 4 can be closed. In the present embodiment, the interval between the concave portion and the convex portion is 45 degrees, and the concave and convex portions are repeated. However, the present invention is not limited to this, and it is sufficient to carry out at a predetermined interval.

  The cam follower 8b of the cam mechanism 8 is disposed so as not to rotate and to advance and retract with respect to the housing 11, and has a first urging member 10a behind the cam follower 8b. The first urging member 10a is fully extended in a state where the backflow prevention by the screw 3 is released (non-compressed state), and the screw 3 moves forward to close the flow path 4a of the plasticizing chamber 4 so as to prevent the backflow. In this state, a predetermined compression amount is compressed, and a pressure (pressing force) larger than that of the molten resin that receives the injection pressure and tries to flow backward through the flow path 4a is generated. Further, the first urging member 10a has a slight variation in the length of the screw 3 due to thermal expansion or the like, and even if the advance distance required for the backflow prevention of the screw 3 actually varies. It is provided in order to absorb the changed amount and prevent damage to the device such as the screw 3. In the present embodiment shown in FIG. 1, a gap S1 is formed between the rear end surface of the cam follower 8b and the casing 11, and a gap S1 exceeding the compression stroke Xs of the first urging member 10a is secured. ing. The first urging member 10a is set to the distance do of the gap S1 when not compressed, the first urging member 10a is set to the distance dm of the gap S1 when the predetermined compression amount is compressed, and do> dm> zero. Good to have. The compression stroke Xs of the first urging member 10a can also be expressed as a distance (Xs = do−dm) obtained by subtracting the distance dm from the distance do. In addition, as the 1st biasing member 10a, a compression coil spring member, a disc spring member, a leaf | plate spring member, etc. may be used, and the member to bias other than that may be used. In the present embodiment, the first urging member 10a is disposed between the rear end portion of the cam follower 8b and the housing 11, but instead, for example, between the screw 3 and the check shaft 7. For example, the first urging member 10a may be disposed at a place where the same effect as described above can be obtained. In this embodiment, the end face cam 8a is adopted as the cam 8a of the cam mechanism 8. However, the present invention is not limited to this, and various cams such as a cylindrical face cam and a positive cam can be adopted. good. In particular, if a positive cam or the like is employed, a configuration in which the cam 8a and the cam follower 8b are always joined can be maintained in addition to the configuration described later. In the cam mechanism 8, the cam follower 8 b may be fastened to the outer ring 6 a of the cam side clutch 6, and the cam 8 a may be disposed in the housing 11 in a non-rotating state.

A screw 3 is connected to the check shaft 7, and a plasticizing reaction force receiver 14 is provided via a thrust bearing 13. The plasticizing reaction force receiver 14 moves back and forth in the housing 11 as the check shaft 7 moves back and forth. That is, the screw 3 connected to the non-return shaft 7 can be retracted until the plasticizing reaction force receiver 14 comes into contact with the stopper portion 11a protruding from the inner peripheral surface of the casing 11, and the plasticizing reaction force receiver 14 does not move backward beyond the position where it abuts against the stopper 11a (screw retreat limit position). Since the non-return shaft 7 is provided with a plasticizing reaction force receiver 14 via a thrust bearing 13, it can be rotated even at a position where the backward movement is restricted. Here, the plasticizing reaction force is generated due to plasticizing and melting while sending the resin material toward the front of the screw 3 by the rotation of the screw 3 and sending the molten resin material toward the injection chamber 20. It is the pressure which acts on the screw 3 and tries to retract the screw 3.
Therefore, in the present embodiment, the distance from the screw retract limit position of the screw 3 to the position where the screw 3 moves forward and closes the flow path 4a is the distance that the screw 3 moves forward to prevent backflow (FIG. 3). Middle backflow stop stroke Xa). The backflow stop stroke Xa can also be expressed by a gap S2 that can be formed by the plasticizing reaction force receiver 14 separating from the stopper portion 11a.
In the present embodiment, a thrust bearing 13 is provided between the check shaft 7 and the plasticizing reaction force receiver 14, and a thrust bearing is provided between the outer ring 9 a of the screw side clutch 9 and the plasticizing reaction force receiver 14. The plasticizing reaction force receiver 14 is attached in the form of providing. As another embodiment, as shown in FIG. 4, a thrust bearing 13 is provided between the check shaft 7 and the plasticizing reaction force receiver 14, and the check shaft 7 and the plasticizing reaction force receiver 14 are provided. A form in which a bearing is provided between them may be used. Moreover, as long as the plasticizing reaction force receiver 14 is mounted so as to perform the same function as the above-described embodiment, any configuration and mounting method may be used. Further, although the stopper portion 11a uses a stepped portion formed by reducing the diameter of the inner hole in the housing, the stopper portion 11a is not limited to the present embodiment as long as the same function can be achieved.

Next, operation | movement of the screw prep plastic type injection apparatus 1 of this Embodiment is demonstrated.
The outline of the operation related to plasticization of the injection apparatus 1 is as follows. The injection device 1 sends out the resin material toward the front of the screw 3 while plasticizing and melting the resin material by the rotation of the screw 3, supplies the molten resin material into the injection chamber 20 through the flow path 4a, and the injection chamber 20 When a predetermined amount of molten resin material is stored in the inside, the supply is stopped, the flow path 4a is closed by the backflow prevention mechanism 2 (shaft coupling that performs a predetermined clutch operation), and the plunger 21 arranged in the injection chamber 20 is closed. Then, the injection filling is performed, and then the blockage of the flow path 4a is opened, and then the molten resin material is supplied to the injection chamber 20 again.

First, at the time of plasticization in which the molten resin material is supplied to the injection chamber 20 by the rotation of the screw 3, the motor (driving means) M is rotated counterclockwise as viewed from the rear of the screw 3 as shown in FIG. Rotation), the rotation shaft 5 rotates, and the outer ring 9a of the screw side clutch 9 fastened to the rotation shaft 5 rotates counterclockwise. When the outer ring 9a of the screw side clutch 9 rotates counterclockwise, the rotation direction coincides with the allowable rotation direction of the screw side clutch 9, so that the outer ring 9a and the inner ring 9b of the screw side clutch 9 are brought into an engaged state and are rotated. Then, the check shaft 7 rotates through the inner ring 9b, and the screw 3 is rotated. The rotation of the screw 3 plasticizes and melts the resin material, and the molten resin material is sent to the injection chamber 20 through the flow path 4a and accumulated. At this time, the inner ring 6b of the cam side clutch 6 connected to the rotating shaft 5 also rotates counterclockwise (forward rotation), but is different from the allowable rotation direction of the cam side clutch 6, and therefore the inner ring 6b of the cam side clutch 6 is. The outer ring 6a is not fastened. Accordingly, the backflow prevention mechanism 2 enters a non-functioning state because the cam 8a connected to the outer ring 6a of the cam side clutch 6 does not rotate (the motor M continues to rotate).
Here, in the present embodiment, the screw 3 is not moved directly in the backward direction by the cam mechanism 8 but in the backward direction (right side in the figure) using the plasticizing reaction force received by the screw 3 during plasticization. It is configured to move. Therefore, at the start of plasticization, as shown in FIG. 3, the opening on the plasticizing chamber side of the flow path 4a is closed at the tip of the screw 3, but the recess of the cam 8a and the cam follower 8b face each other. And a gap corresponding to the backflow stop stroke Xa (a gap that allows the screw 3 to retreat) S3 is vacant between the concave portion of the cam 8a and the cam follower 8b, and the first urging member The pressure (pressing force) that pushes the screw 3 forward by 10a is not applied. For this reason, at the initial stage of plasticization shown in FIG. 3, the screw 3 placed in the forward position as described above receives the plasticizing reaction force generated by the positive rotation of the screw 3 and immediately starts to retract. Then, until the plasticizing reaction force receiver 14 comes into contact with the stopper 11a at the stop position, the screw 3 moves backward, the cam 8a moves backward, and the concave portion and the cam follower 8b come into contact. That is, the screw 3 moves backward by the same distance as the backflow stop stroke Xa, and the opening on the plasticizing chamber 4 side of the flow path 4a is completely opened. At this time, the screw 3 continues to rotate forward at the screw retract limit position without retreating beyond the screw retract limit position.

Next, when the backflow of the molten resin material is stopped, as shown in FIG. 2, when the motor M is rotated clockwise as viewed from the rear of the screw 3, the rotating shaft 5 rotates in the opposite direction to that during plasticization. Then (in reverse rotation), the inner ring 6b of the cam side clutch 6 fastened to the rotary shaft 5 rotates clockwise. When the inner ring 6b of the cam side clutch 6 rotates in the clockwise direction, the outer ring 6a and the inner ring 6b of the cam side clutch 6 are engaged, and the cam 8a coupled to the outer ring 6a (cylindrical end cam 8a in the figure) rotates. To do. In the present embodiment, when the cam 8a is rotated clockwise by a predetermined rotation angle (reverse rotation), the cam surface that contacts the cam follower 8b is switched from the concave portion to the convex portion, and the cam 8a itself and the cam follower 8b The distance is increased so that the screw 3 moves forward (to the left in the figure), and the screw 3 is moved in the reverse flow stop direction (the left direction in FIG. 1, the screw 3) via the cam side clutch 6, the screw side clutch 9, and the check shaft 7. To prevent the backflow. Here, a first urging member (spring member) 10a is disposed behind the cam follower 8b, and from the state where the screw 3 closes the flow path 4a by the compression of the first urging member 10a, the flow path 4a is further increased. Is pressed in the closing direction. Therefore, in the present embodiment, the cam 8a moves forward until the cam surface that contacts the cam follower 8b is displaced from the concave portion to the convex portion by rotating the cam 8a backward by a predetermined angle, and the screw 3 After the screw 3 starts moving forward from the screw retreat limit position and the screw 3 closes the flow path 4a that opens in the front wall of the plasticizing chamber 4, the cam follower 8b moves backward and is provided behind the cam follower 8b. The urging member 10a is compressed to generate a force (pressing force) that presses the screw 3 against the opening of the flow path 4a. The pressing force of the first urging member 10a is such that the molten resin material stored in the injection chamber 20 is larger than the pressure at which the molten resin material tries to flow back to the plasticizing chamber 4 through the flow path 4a during injection filling. It is. Further, the first biasing member 10a is expanded or contracted by the first biasing member 10a even if the distance that the actual screw 3 moves forward is changed due to thermal expansion or contraction of the screw 4. Therefore, the screw 3 can be prevented from being backflow-prevented with an excessive pressure, and the pressure required for backflow prevention can be applied to the screw 3 without being excessive or insufficient. A difference Xd between the height dimension of the concave portion and the convex portion formed on the cam surface of the cam 8a is a reverse flow stop stroke Xa and a compression stroke indicating an amount by which the first urging member 10a is compressed to be in the reverse flow stop state. It is preferable to be equal to the sum of Xs (Xd = Xa + Xs). Further, in the backflow preventing state, the cam follower 8b has a distance dm (dm> zero) of the gap S1 behind the cam follower 8b even when the first urging member 10a is compressed.

  On the other hand, the outer ring 9a of the screw side clutch 9 connected to the rotating shaft 5 also rotates clockwise (reverse rotation). However, the outer ring 9a of the screw side clutch 9 is different from the rotation allowable direction of the screw side clutch 9. 9b is in a state in which the fastening is released, the torque for rotating the screw 3 is cut by the screw side clutch 9, and the flow path 4a is closed without the screw 3 rotating. That is, when the driving means M rotates the rotary shaft 5 in the reverse direction, the screw 3 moves forward without rotating and closes the flow path 4a to the injection chamber with a predetermined pressing force. Therefore, since the screw 3 closes the flow path 4a in a stationary state, the screw 3 does not turn or scrape the opening of the flow path 4a, and the screw 3 does not turn or scrape.

  After performing the injection process in the state of backflow prevention, as shown in FIG. 3, the drive means (motor) M is further rotated clockwise by a predetermined angle (reverse rotation, that is, rotation opposite to that during plasticization). ), The cam-side clutch 6 is engaged with the outer ring 6a and the inner ring 6b, and the cam 8a is rotated clockwise by a predetermined angle. Then, the cam surface of the end cam 8a facing the cam follower 8b is switched from the convex portion to the concave portion. Therefore, the distance between the cam 8a itself and the cam follower 8b is changed to be small. At this time, as described later, in this embodiment, when the concave portion of the cam surface of the end cam 8a and the cam follower 8b face each other. In addition, a gap is formed between the cam surface and the cam follower 8b (that is, the contacted state cannot be maintained). Therefore, in the present embodiment, the cam 8a itself remains in the same position until the cam surface that contacts the cam follower 8b is displaced from the convex portion to the concave portion by rotating the cam 8a backward by a predetermined angle. The cam follower 8b is moved toward the cam 8a until the compression of the first urging member 10a is released and extended (that is, a distance corresponding to the compression stroke Xs) while keeping the position of the screw 3 advanced for backflow prevention. When the cam surface recess and the cam follower 8b face each other after moving forward (advancing to the left in the figure), the clearance S3 (that is, the backflow stop stroke Xa) is sufficient to allow the screw 3 to retreat between the recess and the cam follower 8b. (Corresponding distance) becomes free. At this time, the screw 3 is in a state in which the pressing force at the time of backflow prevention is released, but is still in the advanced position at the time of backflow prevention. The backward movement of the screw 3 is performed in the initial stage of the subsequent plasticization by the screw 3 receiving the plasticizing reaction force and being retracted (retracted to the right side in the figure), that is, to the screw retract limit position, This is performed until the concave portion of the cam surface and the cam follower 8b come into contact with each other or until the plastic reaction force receiver 14 comes into contact with the stopper 11a.

(Second Embodiment)
FIG. 5 is a cross-sectional view showing the second embodiment. In the second embodiment, a second urging member 10b that presses the check shaft 7 toward the drive means M is arranged to constitute a backflow prevention mechanism 12 (shaft coupling that performs a predetermined clutch operation). . The first urging member 10a provided behind the cam follower 8b presses the screw 3 against the backflow of the molten resin material, and applies a pressing force necessary for backflow prevention to the screw 3. On the other hand, the second urging member 10b added in the second embodiment is for forcibly retracting the screw 3 to the screw retreat limit position, and is the total weight from the screw 3 to the rotary shaft 5, that is, It is sufficient that the pressing force is sufficient to retract the total weight of at least the screw 3, the check shaft 7, the plasticizing reaction force receiver 14, the clutches 6 and 9, the cam 8a, the rotating shaft 5, and other bearings. The urging force of the first and second urging members 10a and 10b is greater in the first urging member 10a than in the second urging member 10b. Thus, while the backflow prevention is performed, the first urging member 10a compresses the second urging member 10b, and at the same time, the pressing force necessary for the backflow prevention is applied to the screw 3.
As described above, in the second embodiment, since the cam 8a and the cam follower 8b can always maintain a contact state, unlike the first embodiment, together with the operation of the cam mechanism 8, In addition to releasing the pressure at the time of backflow prevention of the screw 3, the screw 3 advanced at the time of backflow prevention can be forcibly retracted to the screw retreat limit position. That is, after the injection process is performed with the backflow stopped, the cam 8a is reversely rotated by a predetermined angle until the cam surface contacting the cam follower 8b is displaced from the convex portion to the concave portion. The cam follower 8b advances to the cam 8a side until the compression of the biasing member 10a is released and fully extended, and then the cam 8a is pressed to the cam follower 8b side via the check shaft 7 by the second biasing member 10b. Until the contact between the cam surface and the cam follower 8b is always maintained and the concave portion of the cam surface is in contact with the cam follower 8b, that is, as shown in FIG. 5, the screw 3 moves backward with the rotation of the cam 8a. Retreat to the limit position. In the present embodiment, the screw 3 is fastened to the check shaft 7 so that it cannot rotate and cannot be advanced and retracted, and the screw 3 rotates together with the check shaft 7 and advances and retracts together. Yes. The position where the second urging member 10b is provided may be provided at a position different from that of the present embodiment as long as the same operational effects of the present embodiment can be obtained.

  As described above, the present invention is not limited to the embodiment described above. For example, the backflow prevention mechanism may be a mechanism that releases the connection between the input side and the output side when the sensor detects rotation in the reverse direction by the control unit. Moreover, although the rotation direction demonstrated the case where the rotation direction of the screw 3 at the time of plasticization was counterclockwise (positive rotation) seeing the screw 3 from back, rotation of the screw 3 at the time of plasticization (or mixing) If the direction is clockwise when the screw 3 is viewed from the rear, the clockwise rotation may be set to the normal rotation. In addition to the configuration in which the screw 3 as described in the embodiment is advanced to prevent the flow path 4a from being backflowed, the screw preplar type injection device has the flow path 4a that is reversely flown by moving the screw 3 backward. It goes without saying that the present invention can also be applied to such a configuration. In addition, the screw prep plastic type injection device includes a screw prep plastic type injection device in which a back flow prevention wall for preventing the back flow of the molten resin material is disposed in the plasticizing chamber. Needless to say, the present invention is also applicable to a pre-plastic injection device. Further, the present invention can be applied to a liquid resin injection molding machine for injection molding a thermosetting resin material by using a mixing cylinder and a mixing screw instead of the plasticizing cylinder and the plasticizing screw. In addition, the present invention plasticizes and melts or mixes the molding material in the cylinder with a screw and supplies the molding material in a molten state or mixed state separately to the injection cylinder via a flow path, and the injection cylinder with a plunger. Any injection device can be used as long as it is an injection device that injects and fills a mold with a molten or mixed molding material stored in an injection chamber.

1 injection device (screw pre-plastic injection device),
2,12 A shaft coupling (backflow prevention mechanism) that performs a predetermined clutch operation,
3 Screw (plasticized screw),
4 Plasticizing chamber, 4a flow path,
5 rotating shaft,
6 cam side clutch, 6a outer ring, 6b inner ring,
7 Check shaft,
8 cam mechanism, 8a cam (end face cam), 8b cam follower,
9 Screw side clutch, 9a Outer ring, 9b Inner ring,
10a 1st biasing member (spring member), 10b 2nd biasing member (spring member),
11 Housing, 11a Stopper for receiving plasticizing reaction force,
14 Receiving plasticizing reaction force,
20 Injection chamber,
M drive means (motor),
S1 A gap between the rear end face of the cam follower and the housing (a gap exceeding the compression stroke Xs of the first urging member),
S2 A gap between the plasticizing reaction force receiver and the stopper (a gap generated when preventing backflow),
S3 A gap between the cam surface of the cam and the cam follower (a gap that allows the screw to move backward),
Xa Backflow stop stroke (gap generated when backflow is prevented),
Xd The difference in height between the concave and convex portions of the cam surface,
Xs Compression stroke of the first biasing member

Claims (7)

The molding material in the cylinder is plasticized, melted or mixed with the screw, and the molten or mixed molding material is supplied to the injection cylinder separately provided through the flow path, and stored in the injection chamber in the injection cylinder with the plunger. In an injection apparatus for injection-filling a mold with a molten or mixed molding material,
The screw and the drive means are connected by a shaft coupling that performs a predetermined clutch operation, and the shaft coupling includes at least a clutch, a cam, and a cam follower,
When the driving means rotates the rotating shaft in the forward direction, the rotational force is transmitted to the screw to supply a molding material in a molten state or a mixed state to the injection chamber ,
When the driving means reversely rotates the rotating shaft, the rotational force is transmitted to either the cam or the cam follower, and the screw moves forward or backward by the relative displacement of the cam and the cam follower to move to the injection chamber. An injection apparatus characterized in that the flow path is closed to prevent backflow of a molten or mixed molding material. The shaft joint, in the rotating shaft coaxially, the clutch, the cam and the cam follower are at least provided,
When the rotary shaft is rotated forward, the rotational force is not transmitted to the cam or the cam follower by the clutch, but the rotational force is transmitted to the screw to inject the molten or mixed molding material. Supply to the room,
When the rotary shaft is rotated in the reverse direction, the rotational force is not transmitted to the screw by the clutch, but the rotational force is transmitted to either the cam or the cam follower. 2. The injection apparatus according to claim 1, wherein the screw is moved forward or backward by displacement to close the flow path to the injection chamber and prevent the molten or mixed molding material from backflowing. The clutch comprises a one-way clutch only the rotation power of the positive rotation of the rotary shaft as a screw-side clutch. Used to transmitted to the screw, either only the rotation force of the reverse rotation of the rotary shaft of the cam or the cam follower while the consists of a one-way clutch as a cam clutch. Used to transfer either
When the rotating shaft is rotated forward, the rotational force is transmitted to the screw, and the screw rotates to supply the molten molding material to the injection chamber,
When the rotating shaft is rotated in the reverse direction, the rotational force is not transmitted to the screw, and each time the rotating shaft is rotated in the reverse direction at a predetermined angle, the screw is moved forward or backward to close the flow path of the injection chamber and back flow. Switching between the state of stopping and the state of releasing only the pressing force for the backflow prevention or the state of opening the flow path by retreating or advancing in the opposite direction to the case of backwashing the screw in addition to the release. The injection device according to claim 1 or 2. When allowed to advance or retract the screw closes the aperture of the flow path, it is provided as the first urging member for generating a pressing force required to reverse flow stopping claim 1, wherein 3 The injection device according to any one of the above. The type injection device according to any one of claims 1 to 4, wherein the cam is provided with a second urging member for always bringing the cam follower into contact with the cam surface.   The injection device according to any one of claims 1 to 5, wherein the screw is a plasticizing screw, and the cylinder into which the screw is inserted is a plasticizing cylinder.   The injection device according to any one of claims 1 to 5, wherein the screw is a mixing screw, and the cylinder in which the screw is inserted is a mixing cylinder.

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