JP2012157980A - Injection device, and injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve kneading performance by interlocking movement of a plunger with a torpedo in the kneading time, while making them in the non-interlocking state in the injecting time.SOLUTION: This injection device A includes: a cylinder part 10 having a nozzle 11 at the tip and storing therein an injection material to be ejected from the nozzle; a plunger 20 for extruding the injection material in the cylinder part to be ejected from the nozzle; and a torpedo 30 arranged in the cylinder part at the nozzle side relative to the plunger. The injection device further includes: a first drive means 40 to advance/retreat the plunger in the extrusion direction of the injection material; a second drive means 50 to rotate the plunger around its axis; and an engagement part for engaging the plunger and the torpedo with each other in the rotating direction around the axis of the plunger and preventing them from being engaged with each other in the extrusion direction.

Description

  The present invention relates to an injection device for an injection molding machine.

  As an injection device of an injection molding machine, a screw type and a plunger type are known. The screw-type injection device kneads the injection material in the injection cylinder by rotating the screw. On the other hand, in the plunger type injection device, the plunger itself does not have a kneading function for the injection material. Thus, it is known to provide a tobead in the injection cylinder to improve kneadability. Further, Patent Document 1 discloses a mechanism aimed at further improving the kneadability of the injection material by rotating the tobead.

JP 2009-113360 A

  Here, the kneading of the injection material is preferably performed during the plasticization period between injections. However, since the mechanism of Patent Document 1 links the rotation of the tobead and the movement of the plunger, the injection material is injected when the tobead is rotated at a timing other than the time of injection of the injection material. Although it is conceivable to rotate the tobead by a small amount so as not to be injected, the kneadability is inferior.

  An object of the present invention is to improve the kneadability by making the movement of the plunger and the tobead non-interlocking at the time of injection and interlocking at the time of kneading.

  According to the present invention, a cylinder portion having a nozzle at the tip and containing an injection material injected from the nozzle, a plunger that extrudes the injection material in the cylinder portion and injects it from the nozzle, and the nozzle rather than the plunger A first drive means for advancing and retracting the plunger in the extrusion direction of the injection material; and a second drive means for rotating the plunger about its axis. An injection unit comprising: an engaging part that engages the plunger and the tobead with each other in the rotational direction of the plunger around the axis, and disengages the plunger in the pushing direction. An apparatus is provided.

  Moreover, according to this invention, the injection molding machine provided with the said injection apparatus is provided.

  According to the present invention, the movement of the plunger at the time of injection and the tobead are not interlocked, and at the same time, the kneadability can be improved by interlocking at the time of kneading.

Explanatory drawing of the injection apparatus which concerns on one Embodiment of this invention. (A) is a block diagram of a control part, (B) is sectional drawing which follows the line II of FIG. Operation | movement explanatory drawing of the injection apparatus of FIG. Operation | movement explanatory drawing of the injection apparatus of FIG. The flowchart which shows the example of control of the injection device of FIG. (A) is explanatory drawing of the other structural example of an engaging part, (B) is sectional drawing of a plunger, (C) is sectional drawing of the plunger in alignment with line II-II of FIG. 6 (A), (D) is Sectional drawing of the tobead which follows the line III-III of FIG. 6 (A). 6A is an operation explanatory diagram of the configuration example, FIG. 6B is a cross-sectional view taken along line IV-IV in FIG. 7A, and FIG. 6C is a diagram in which the plunger is rotated 90 degrees from the state of FIG. The figure which shows a state.

  FIG. 1 is an explanatory view (partial sectional view) of an injection apparatus A according to an embodiment of the present invention. The injection device A constitutes an unillustrated injection molding machine. The injection molding machine defines a molding part inside the injection apparatus A and a mold (not shown) having a structure capable of injecting an injection material into the molding part, and a mold for taking out a molded product. A mold clamping device (not shown) that performs opening and closing, mold clamping, and the like, and when a molten injection material (typically a resin material) is supplied from the injection device A into the mold, the molded product is formed in the molding section. Perform injection molding.

<Configuration of injection device A>
The injection device A includes a plate-like lower base portion 1, a plate-like upper base portion 2, and a plurality of support columns 3 that connect them. Between the lower base portion 1 and the upper base portion 2, a plate-like stage portion 4 is fixedly disposed on the support column 3. The injection apparatus A also includes a cylinder part 10, a plunger 20, a tobead 30, and drive units 40 and 50.

  The cylinder part 10 is formed in a cylindrical shape, and the inside of the cylinder part 10 is vertically penetrated to form an accommodation space 10a for the injection material. A material supply opening 10b communicating with the accommodation space 10a is formed in the peripheral wall of the cylinder portion 10, and the material supply device B is attached thereto. The material supply device B is a device for supplying the injection material in the hopper b storing the granular injection material into the accommodation space 10a through the opening 10b, and the material delivery mechanism may be a screw type or a plunger. It may be a formula. Note that the opening 10b, the material supply device B, and the hopper b exist at positions that do not appear in FIG.

  A nozzle 11 is provided at the tip (lower end) of the cylinder portion 10, and the injection material in the accommodation space 10 a is injected from the nozzle 11. A heater 12 is provided around the cylinder portion 10, and the injection material in the accommodation space 10 a is melted by the heat.

  A plunger 20 is provided in the accommodation space 10a so as to freely advance and retract. In the case of this embodiment, the plunger 20 is provided with a hole portion 21 opened at the tip end surface (lower end surface) thereof, and has a cylindrical shape with a circular outer periphery. The plunger 20 is movable in the vertical direction in the figure, and descends downward to push the injection material in the accommodation space 10 a and inject it from the nozzle 11.

  A tobead 30 is also disposed in the accommodation space 10 a on the nozzle 11 side of the plunger 20. The toe bead has a cylindrical central portion, and a plurality of grooves 32 forming a passage for the injection material are formed on the peripheral surface thereof. The injection material pushed out by the plunger 20 passes through the groove 32, so that heating and kneading are promoted. The shape of the tobead 30 is not limited to this, and various shapes can be adopted.

  The tobead 30 is provided with an axial insertion portion 31 inserted into the hole portion 21 of the plunger 20 at the upper portion. Here, the hole portion 21 and the insertion portion 31 engage the plunger 20 and the tobead 30 with each other in the rotational direction around the axis of the plunger 20, and the extrusion direction (the axial direction of the cylinder portion 10, FIG. In the up and down direction), engaging portions that are not engaged with each other are configured. FIG. 2B is a cross-sectional view taken along line II in FIG.

  As shown in the figure, in the case of this embodiment, the hole 21 has an oval cross-sectional shape, and the insertion portion 31 also has an oval cross-sectional shape. For this reason, the insertion portion 31 and the hole portion 21 can be relatively displaced in the extrusion direction, but cannot be relatively displaced in the rotational direction around the plunger 20 axis.

  In the present embodiment, the cross-sectional shapes of the hole 21 and the insertion portion 31 are oval, but the present invention is not limited to this, and various shapes other than a circle, such as a rectangle and an ellipse, can be employed. Moreover, in this embodiment, although the hole part 21 was provided in the plunger 20 side and the insertion part 31 was provided in the toe bead 30 side, these are good also as a reverse relationship. Furthermore, instead of the hole portion and the insertion portion, for example, engagement pieces that engage with each other in the rotation direction may be protruded from the plunger 20 and the tobead 30. However, the length of the plunger 20 in the axial direction can be shortened by adopting the configuration of the hole portion and the insertion portion.

  Returning to FIG. 1, the drive unit 40 is a mechanism for moving the plunger 20 back and forth in the extrusion direction of the injection material, and the drive unit 50 is a mechanism for rotating the plunger 20 around its axis. In the present embodiment, the following configurations are employed as these configurations, but other configurations having the same function can also be employed.

  The drive unit 40 includes a motor 41 supported by the upper base portion 2. The motor 41 is, for example, a stepping motor. A pulley 42 is attached to the output shaft of the motor 41. A ball nut 45 is also rotatably supported on the upper base portion 2. A pulley 43 is fixed to the upper portion of the ball nut 45, and an endless belt 44 is wound around the pulley 42 and the pulley 43.

  A ball screw shaft 46 is screwed onto the ball nut 45, and a movable stage portion 47 is fixed to the lower end portion thereof. The movable stage portion 47 is guided and supported by the column 3 and is movable (movable up and down) in the axial direction of the column 3. The movable stage portion 47 supports the upper end portion of the plunger 20 so as to be rotatable about its axis.

  Thus, when the motor 41 is driven, the ball nut 45 is rotated by the rotation of the pulleys 42 and 43. Since the ball nut 45 is supported by the upper stage portion 2 so as not to move in the vertical direction, the ball screw shaft 46 moves upward or downward according to the rotation direction of the motor 41. As a result, the movable stage portion 47 and the plunger 20 also move upward or downward.

  FIG. 3 shows an operation mode of the injection apparatus A at the time of injection, and the plunger 20 is lowered downward by the rotation of the motor 41. As a result, the injection material in the accommodation space 10a is injected from the nozzle 11. In addition, since the insertion part 31 is inserted in the hole 21, the injection material hardly enters the hole 21. The tobead 30 does not move although the depth of entry of the insertion portion 31 into the hole portion 21 is increased.

  Returning to FIG. 1, the drive unit 50 includes a motor 51 supported by the movable stage unit 47. The motor 51 is, for example, a stepping motor. A pulley 52 is attached to the output shaft of the motor 51. A pulley 53 is fixed to the plunger 20, and an endless belt 54 is wound around the pulley 52 and the pulley 53. Since the motor 51, the pulley 52, and the endless belt 54 are present at positions not shown in FIG.

  Thus, when the motor 51 is driven, the plunger 20 rotates about its axis by the rotation of the pulleys 52 and 53. At this time, the tobead 30 is also rotated by the engagement between the hole portion 21 and the insertion portion 31, and the surrounding injection material is kneaded. FIG. 4 shows an operation mode of the injection apparatus A during kneading, and the plunger 20 and the tobead 30 are rotated by the rotation of the motor 51. Thus, in this embodiment, by restricting the engagement direction between the hole 21 and the insertion portion 31, the movement of the plunger 20 at the time of injection and the toe bead 30 are not interlocked with each other, and the kinematics are rotated together while being kneaded. Thereby, kneadability can be improved. If the plunger 20 is rotated at the time of injection, the tobead 30 is also rotated. Therefore, the injection material can be kneaded by the rotation of the tobead 30 even during the injection operation.

<Control unit>
Next, the configuration of the control system will be described with reference to FIG. The control unit 100 can control the entire injection molding machine including the injection apparatus A, and includes a CPU 101, a storage unit 102, and an I / F (interface) 103. The CPU 101 acquires the detection result of the sensor 108 and controls the motor 106, the heater 107, and the like according to a program stored in the storage unit 102.

  The storage unit 102 includes, for example, a ROM, a RAM, a hard disk, and the like. The I / F 103 is an interface between the CPU 101 and an external device. The input unit 104 is, for example, a keyboard or a mouse. An operator can input various parameters related to operation commands and molding conditions to the control unit 100 via the input unit 104. The display unit 120 is a display such as an LCD, for example, and displays information on an injection molding machine including the injection apparatus A.

  The motor 106 includes motors 41 and 51. The heater 107 includes the heater 12. The sensor 108 includes an encoder that detects the amount of rotation of the motors 41 and 51, for example, as a sensor that can be used to detect the position (extrusion direction and rotation direction) of the plunger 20.

<Example of injection control>
Next, an example of control executed by the CPU 101 will be described with reference to FIG. FIG. 5 is a flowchart showing a control example of the injection apparatus A. When the CPU 101 controls the entire injection molding machine provided with the injection apparatus A, the mold clamping apparatus is also controlled. FIG. 5 shows only the processes related to the injection process of the injection material.

  In the case of this embodiment, the injection material is kneaded by rotating the tobead 30 after the injection of the injection material until the next injection, that is, during the plasticization period of the injection material. Thereby, the kneadability of the injection material newly supplied to the accommodation space 10a and the existing molten or semi-molten injection material can be improved.

  In S1, it is determined whether or not the mold clamping of the mold clamping device is completed. If applicable, the process proceeds to S2. If not applicable, the process waits. In S2, the kneading is finished. Details will be described later. In S3, the drive unit 40 is operated to lower the plunger 20 (FIG. 3), and the injection material is injected. In S4, the drive unit 40 (motor 41) is actuated to raise the plunger 20, and the plunger 20 is moved to a position where the new injection material can be supplied (position in FIG. 1).

  In S5, the drive unit 50 (motor 51) is operated to rotate the plunger 20 and the toe bead 30, and the injection material is kneaded by the rotation of the toe bead 30. Thereafter, the process returns to S1. The drive unit 50 is operated until the end of kneading in S2. Here, the period from the injection in S3 to the completion of the mold clamping in S1 is a plasticizing period of the injection material in which the molded product is cooled, the mold is opened, and a new injection material is supplied in parallel. By kneading the injection material by rotating the tobead 30 during this period, a longer kneading time can be secured, and the injection material newly supplied to the accommodation space 10a and the existing molten or semi-molten injection material And kneadability can be improved.

  From the viewpoint of improving kneadability, it is preferable to change the rotational speed of the tobead 30 during the plasticization period. For this reason, the rotation speed of the plunger 20, that is, the rotation speed of the motor 51 may be gradually increased, for example. Further, it may be changed periodically such as slow → fast → slow → fast.

<Other examples of engaging parts>
In the above embodiment, the hole portion 21 and the insertion portion 31 are engaged in the rotation direction and disengaged in the extrusion direction, but the extrusion direction of the plunger 20 and the tobead 30 is also relative to the extrusion direction. When the position and the relative position in the rotation direction of the plunger 20 with respect to the toe bead 30 are respectively predetermined positions, the plunger 20 and the toe bead 30 can be engaged with each other. Thus, not only the tobead 30 is rotated, but also the injection material can be kneaded by reciprocating in the extrusion direction.

  FIG. 6A is an explanatory diagram of another configuration example of the engaging portion. The plunger 20 has a hole portion 21 as in the above embodiment, but the cross-sectional shape of the plunger 20 is different from the other portions in the region R. FIG. 6B shows a cross-sectional shape of the hole 21 in a portion other than the region R, and has an oval shape as in the above embodiment. FIG. 6C shows the cross-sectional shape of the hole 21 (R) in the region R, which is a circle (perfect circle) with a size inscribed by the elliptical shape that is the cross-sectional shape of the other part.

  On the other hand, the tobead 30 has a configuration in which the insertion portion 310 is connected to the tobead 30 via a cylindrical shaft 311, and the cross-sectional shape thereof is the same length as the hole portion 21 as shown in FIG. It has a circular shape.

  Next, the operation of the engaging portion will be described with reference to FIG. FIG. 7A shows a state where the insertion portion 310 is positioned in the hole portion 21 (R), and FIG. 7B is a cross-sectional view thereof. Since the hole 21 (R) is circular, the insertion part 310 and the hole 21 (R) are not engaged even in the rotational direction. Therefore, when the plunger 20 is rotated 90 degrees by the drive unit 50, the plunger 20 and the tobead 30 are relatively displaced by 90 degrees as shown in FIG.

  In this state, the insertion portion 310 is engaged with the upper surface and the lower surface of the inner wall of the hole portion 21 (R), so that the engagement state is established in the pushing direction. Therefore, by reciprocating the plunger 20 in the extrusion direction by the drive unit 40, the tobead 30 can be reciprocated in the extrusion direction, and the injection material can be kneaded. The reciprocating movement of the plunger 20 is preferably sufficiently smaller than the moving distance at the time of injection so as not to inject the injection material.

  When the plunger 20 is rotated 90 degrees by the drive unit 50 from the state shown in FIG. 7C, the state returns to the state shown in FIG. 7B, and the engagement state in the pushing direction between the insertion portion 310 and the hole portion 21 (R). Is released. Therefore, the tobead 30 does not move when the plunger 20 is lowered at the time of injection. Moreover, if the insertion part 310 is removed from the hole part 21 (R) and positioned at another part of the hole part 21, the hole part 21 and the insertion part 31 are engaged in the rotational direction as in the above embodiment. Therefore, the injection material can be kneaded by rotating the tobead 30.

  Kneading of the injection material by reciprocating movement of the tobead 30 can also be performed during the plasticization period. At that time, it is preferable to change the reciprocating speed of the tobead 30 during the plasticizing period in terms of improving kneadability. For this reason, the reciprocating speed of the plunger 20, that is, the forward / reverse rotational speed of the motor 51 may be gradually increased, for example. Further, it may be changed periodically such as slow → fast → slow → fast.

  The kneading of the injection material by the reciprocating movement of the tobead 30 and the kneading of the injection material by the rotation of the tobead 30 can be sequentially performed. For example, the injection material is first kneaded by the reciprocating movement of the tobead 30, and then the injection material is kneaded by the rotation of the tobead 30. Kneading of the injection material newly supplied by the former kneading and the existing injection material is promoted, and the whole kneading is further promoted by the latter kneading.

Claims (8)

A cylinder having a nozzle at the tip and containing an injection material injected from the nozzle;
A plunger that extrudes the injection material in the cylinder part and injects it from the nozzle;
A tobead disposed in the cylinder part on the nozzle side of the plunger,
In an injection device comprising:
First driving means for moving the plunger back and forth in the extrusion direction of the injection material;
Second driving means for rotating the plunger around its axis;
An engagement portion that engages the plunger and the tobead with each other in the rotation direction of the plunger around the axis, and disengages the plunger in the extrusion direction;
An injection apparatus comprising: The engaging portion is
When the relative position in the pushing direction between the plunger and the tobead and the relative position in the rotational direction of the plunger with respect to the tobead are respectively predetermined positions, the plunger and the tobead are moved in the pushing direction. The injection device according to claim 1, wherein the injection devices are engaged with each other.   The said engaging part was provided with the hole formed in one of the said plunger and the said tobead, and the insertion part inserted in the said hole formed in the other, The Claim 1 or 2 characterized by the above-mentioned. Injection device. Control means for controlling the first and second drive means;
The injection device according to any one of claims 1 to 3, wherein the control means rotates the plunger after the injection material is injected and before the next injection.   The injection device according to claim 4, wherein the control unit rotates the plunger while changing a rotation speed between the injection of the injection material and the next injection. Control means for controlling the first and second drive means;
The control means moves and rotates the plunger to the predetermined position after the injection of the injection material and before the next injection, and reciprocates the plunger in the extrusion direction, thereby The injection apparatus according to claim 2, wherein the injection apparatus is reciprocally moved in the extrusion direction.   The control means reciprocates while changing the movement speed in the extrusion direction by changing the movement speed in the extrusion direction by changing the movement speed in the extrusion direction after the injection of the injection material until the next injection. The injection apparatus according to claim 6, wherein the injection apparatus is moved.   An injection molding machine comprising the injection device according to any one of claims 1 to 7.

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