JP2004106388A - Injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding machine capable of preventing a fixed die plate from being deformed by a nozzle touch force. <P>SOLUTION: The injection molding machine 10A is provided with the fixed die plate 12, a barrel part 13, an injection part 14, a nozzle touch mechanism 30 and an injection base moving mechanism 70. The barrel part 13 comprises a barrel 20 and a barrel base part 21. A screw 22 is inserted into the barrel 20. The injection part 14 has an injection driving part 41 for moving the screw 22 in the axial X direction, and an injection base part 42 provided on the injection driving part 41. The nozzle touch mechanism 30 moves the barrel part 13 in the axial X direction. The injection base moving mechanism 70 moves the injection part 14 in the axial X direction in accordance with a position of the barrel part 13 so as to hold the barrel part 13 and the injection part 14 at a specified relative distance. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an injection molding machine for injection molding resin, metal, rubber, or the like.
[0002]
[Prior art]
FIG. 7 shows an example of a conventional injection molding machine 100. The injection molding machine 100 includes a fixed die plate 102 supporting a mold 101, a barrel 104 having a nozzle 103, a nozzle touch mechanism 105, a screw rotating mechanism 107 for rotating a screw 106, and a screw 106 in an axial direction. It has an injection drive unit 110 for moving. As the injection drive unit 110, an electric motor 112 and a ball screw 113 as shown in FIG. 7 may be used, or a hydraulic cylinder may be used.
[0003]
The barrel 104 and the injection drive unit 110 are fixed to a common frame structure 111. Therefore, during the nozzle touch operation, the barrel 104 and the injection driving unit 110 are integrally reciprocated in the axial direction of the screw 106 by the nozzle touch mechanism 105.
[0004]
The material is melted inside the barrel 104. The material is injected into the mold 101 by advancing the screw 106 by the injection drive unit 110 in a state where the nozzle 103 is in contact with the injection port of the mold 101 by the nozzle touch mechanism 105.
[0005]
In the case where the barrel 104 and the injection drive unit 110 are fixed to the common frame structure 111 as in the injection molding machine 100, the reaction force at the time of injection is reduced by the barrel 104 and the injection drive unit via the frame structure 111. 110.
[0006]
That is, a reaction force (injection reaction force) for advancing the screw 106 is transmitted to the injection drive unit 110, and the injection reaction force is applied in a direction to push back the barrel 104, thereby generating a force for separating the nozzle 103 from the mold 101. When the nozzle 103 moves away from the mold 101, the material leaks from between the nozzle 103 and the mold 101. For this reason, the nozzle 103 needs to be pressed against the mold 101 by the nozzle touch mechanism 105 with a force greater than the injection reaction force.
[0007]
As a result, the fixed die plate 102 tilts or bends, as shown in an exaggerated manner by a two-dot chain line P in FIG. As a result, problems such as a one-sided contact between the fixed mold 101a and the movable mold 101b, and interference of the tie bar of the mold clamping device (not shown) with the guide hole of the mold 11 occur.
[0008]
In order to prevent the fixed die plate 102 from tilting, a conventional technique for improving the nozzle touch mechanism has been proposed. (See, for example, Patent Documents 1 and 2 below)
[0009]
[Patent Document 1]
JP-A-9-277306
[Patent Document 2]
JP 2001-38864 A
[Problems to be solved by the invention]
Although the inclination of the fixed die plate can be reduced to some extent by the above-described prior art, the nozzle is still pressed against the mold with a force higher than the injection reaction force so that the mold and the nozzle do not separate from each other. For this reason, when the injection reaction force increases as in, for example, high-speed injection molding, it is difficult to obtain an appropriate nozzle touch force with a normal nozzle touch mechanism.
[0012]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an injection molding machine capable of preventing a fixed die plate from being deformed and obtaining an appropriate nozzle touch force.
[0013]
[Means for Solving the Problems]
The injection molding machine according to the present invention includes a fixed die plate supporting a mold, a barrel portion having a barrel arranged to face the fixed die plate, and a barrel portion having a barrel base portion provided on the barrel, and the barrel portion. A nozzle touch mechanism that moves the barrel in the axial direction, an injection unit that has an injection drive unit that moves the screw or plunger inserted in the barrel in the axial direction, and an injection base unit that is provided in the injection drive unit, An injection base moving mechanism that is connected to the fixed die plate and moves the injection unit in the axial direction according to the position of the barrel unit so that the barrel unit and the injection unit are maintained at a predetermined relative distance. I have it.
[0014]
In the case of an electric injection molding machine, a motor and an electric mechanism such as a ball screw are used for an injection drive unit. In a hydraulic injection molding machine, a hydraulic device such as a hydraulic cylinder is used for an injection drive unit. In the case of an in-line injection molding machine, a screw is inserted into the barrel, and the screw is driven to rotate by a motor or the like constituting a measuring mechanism. The screw is driven in the axial direction by the injection drive unit.
[0015]
In the case of a pre-plunger-type injection molding machine, a plunger is inserted into the barrel, and the plunger is driven in the axial direction by the injection drive unit. Then, a screw is inserted into a cylinder different from the barrel, and the screw is driven to rotate by a motor or the like.
[0016]
In a preferred embodiment of the present invention, the injection base moving mechanism includes a motor that moves the injection unit in the axial direction, a sensor that detects a relative position between the barrel unit and the injection unit, and a signal output by the sensor. A controller that controls the rotation of the motor so that the barrel unit and the injection unit are maintained at a predetermined relative position based on the above.
[0017]
In a preferred aspect of the present invention, the nozzle touch mechanism includes a connecting member that connects the fixed die plate and the barrel base, and a nozzle touch drive source that moves the connecting member in the axial direction.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
The in-line injection molding machine 10A shown in FIG. 1 includes a fixed die plate 12 for supporting a mold 11, a barrel unit 13, an injection unit 14, and the like. The mold 11 includes a fixed mold 11a fixed to the fixed die plate 12 and a movable mold 11b provided on a movable die plate (not shown). A material injection port 11c is formed in the fixed mold 11a.
[0019]
The barrel portion 13 has a cylindrical barrel 20 disposed to face the fixed die plate 12 and a barrel base portion 21 provided at a base of the barrel 20. A screw 22 is inserted inside the barrel 20. The barrel 20 is provided with a heater (not shown) for heating and melting a material such as a resin.
[0020]
A nozzle 25 is provided at the tip of the barrel 20. The nozzle 25 is located on the axis of the injection port 11 c of the mold 11. At the base of the barrel 20, a hopper 26 for supplying a material into the barrel 20 is provided.
[0021]
A nozzle touch mechanism 30 is provided between the fixed die plate 12 and the barrel base 21. The nozzle touch mechanism 30 includes a rod-shaped connecting member 31 extending in the axis X direction of the barrel 20 and a hydraulic cylinder 32 functioning as a nozzle touch drive source. The connecting member 31 of the nozzle touch mechanism 30 can be moved in the axis X direction by the hydraulic pressure supplied to the cylinder 32 by the hydraulic unit 33. Note that, instead of the hydraulic cylinder 32, an electric actuator using a motor and a ball screw may be employed as the nozzle touch drive source.
[0022]
The injection section 14 includes an injection drive section 41 having a hydraulic cylinder 40 functioning as an injection drive source, an injection base section 42 supporting the hydraulic cylinder 40, a metering mechanism 43, and a screw drive shaft 44 connected to the screw 22. And so on.
[0023]
The hydraulic cylinder 40, which is an example of the injection drive source, includes a cylinder body 50 and a piston 51 provided inside the cylinder body 50. A thrust bearing 52 is provided between the piston 51 and the screw drive shaft 44 so that the screw drive shaft 44 can rotate relative to the piston 51.
[0024]
The piston 51 can be moved in the axis X direction by the hydraulic pressure supplied from the hydraulic unit 33 to the hydraulic cylinder 40. Note that, instead of the hydraulic cylinder 40, an electric actuator using a motor and a ball screw may be adopted as the injection drive source.
[0025]
The screw drive shaft 44 is rotatably supported on the injection base 42 by a bearing 55. A rotating body 57 such as a pulley is spline-engaged with a spline portion 56 formed on the screw drive shaft 44. The torque of the screw rotation motor 59 is transmitted to the screw drive shaft 44 via a force transmission member 58 such as a belt or a gear. The weighing mechanism 43 is constituted by the rotating body 57, the force transmitting member 58, the motor 59, and the like.
[0026]
A bracket 65 is provided on the injection base portion 42. The bracket 65 and the fixed die plate 12 are connected by an injection base moving mechanism 70. An example of the injection base moving mechanism 70 includes a motor 71, a ball screw device 72, and the like.
[0027]
The ball screw device 72 has a feed screw 73 extending in the axis X direction of the barrel 20, and a nut member 74 screwed to the feed screw 73. By rotating the feed screw 73 by the motor 71, the injection base 42 can be moved by the desired amount in the axis X direction via the nut member 74 and the bracket 65. Note that the feed screw 73 may be fixed to the fixed die plate 12 and the nut 71 may be rotated by the motor 71 to move the injection base 42 in the direction of the axis X.
[0028]
A sensor 80 is provided to detect a relative position between the barrel unit 13 and the injection unit 14. A detection signal of the sensor 80 is input to the controller 81. The motor 71 is controlled by the controller 81. That is, the controller 81 controls the rotation of the motor 71 based on the signal output from the sensor 80 so that the barrel unit 13 and the injection unit 14 are maintained at a predetermined relative position.
[0029]
As means for detecting the relative position of the barrel section 13 and the injection section 14 in the direction of the axis X, other than the sensor 80, various linear scales, proximity sensors, potentiometers, and encoders may be used. Alternatively, the position of the barrel 13 and the position of the injection unit 14 may be individually detected, and the relative distance between the barrel 13 and the injection unit 14 may be calculated based on the respective positions by an arithmetic unit such as a microcomputer. Good.
[0030]
Next, the operation of the injection molding machine 10A having the above configuration will be described.
The barrel 13 is advanced in the direction of the axis X by the nozzle touch mechanism 30, and the tip of the nozzle 25 contacts the injection port 11 c of the mold 11. As the barrel 13 advances, the injection base moving mechanism 70 operates. That is, by rotating the motor 71 based on the signal from the sensor 80 so that the barrel portion 13 and the emission portion 14 are kept at a fixed distance from each other, the emission portion 14 is moved in the same direction as the barrel portion 13 by the same distance. Advance.
[0031]
When the screw 22 is rotated by the screw rotation motor 59, the pellet-shaped material (eg, resin) supplied from the hopper 26 is kneaded in the barrel 20 by the screw 22, and is melted by being heated. The molten material accumulates on the tip side of the screw 22.
[0032]
After that, when the screw 22 retreats by a predetermined amount and the desired amount of material accumulates on the distal end side of the screw 22, hydraulic pressure is supplied to the hydraulic cylinder 40 to advance the screw 22 by a predetermined amount, and The molten material is extruded into the mold 11.
[0033]
In the injection molding machine 10A of this embodiment, the injection reaction force applied to the injection drive unit 41 via the screw 22 and the screw drive shaft 44 at the time of injection is reduced by the fixed die plate 12 via the injection base unit 42 and the injection base moving mechanism 70. Is transmitted to. Therefore, the injection reaction force is supported by the fixed die plate 12.
[0034]
On the other hand, since the barrel base portion 21 is separated from the injection base portion 42 and is pressed against the mold 11 by the nozzle touch mechanism 30, the injection reaction force input to the injection drive portion 41 causes the barrel base portion 21 and the barrel 20. Will not be transmitted to
[0035]
For this reason, the tip of the nozzle 25 can be kept in close contact with the mold 11 with a predetermined nozzle touch force. Therefore, the nozzle touch force can be prevented from becoming unstable due to the injection reaction force, and the force for pressing the nozzle 25 can be relatively small, so that the fixed die plate 12 is deformed or the nozzle 25 and the die 11 Problems such as leakage of material from the connection portion can also be prevented.
[0036]
After the injection, the screw 22 is rotated by rotating the screw drive shaft 44 by the screw rotation motor 59. Thereby, the material is kneaded while being fed to the tip end side of the barrel 20, and the molten resin is measured. After the resin injected into the mold 11 has cooled, the mold 11 is opened and the molded product is ejected by the ejector mechanism, thereby completing one cycle of the injection molding process.
[0037]
When the nozzle 25 is separated from the mold 11, the barrel portion 13 is retracted by a predetermined amount by the nozzle touch mechanism 30. Also in this case, the motor 71 rotates based on the signal from the sensor 80 so that the barrel 13 and the injection unit 14 are maintained at a fixed distance with the retreat of the barrel 13, so that the injection unit 14 It retracts by the same distance in the same direction as the barrel 13.
[0038]
FIG. 2 shows a pre-plunger type injection molding machine 10B according to a second embodiment of the present invention. The pre-plunger type injection molding machine 10B has a barrel 20 in which a plunger 90 is stored, and a cylinder 91 in which a screw 22 is inserted. The screw 22 is driven to rotate by a screw rotation motor 59 and a force transmission member 58. Other configurations and operations are the same as those of the in-line injection molding machine 10A of the first embodiment, and therefore, the same reference numerals are given to the same parts as those of the first embodiment, and the description will be omitted.
[0039]
The injection molding machine 10B also has an injection base moving mechanism 70 such that the barrel base 21 and the injection base 42 are separated and the barrel 13 and the injection section 14 are maintained at a predetermined relative distance. As a result, the injection unit 14 moves in the axial direction of the barrel 20. Therefore, the injection reaction force applied to the injection drive unit 41 during injection is not transmitted to the barrel 20. Therefore, the tip of the nozzle 25 can be kept in close contact with the mold 11 by the nozzle touch mechanism 30 with a relatively small nozzle touch force.
[0040]
FIGS. 3 and 4 show an injection molding machine 10C according to a third embodiment of the present invention. The nozzle touch mechanism 30 of the injection molding machine 10C uses a ball screw device 92 and a motor 93. As shown in FIG. 4, the injection base driving mechanism 70 includes a pair of ball screw devices 72a and 72b. When one of the ball screw devices 72a is rotated by the motor 71, the rotational force is transmitted to the other ball screw device 72b via a force transmitting member 94 such as a belt or gear.
[0041]
The injection molding machine 10C of this embodiment can move the injection unit 14 in the axial direction of the barrel 20 by rotating the ball screw devices 72a and 72b by the motor 71. The other basic configuration and operation are the same as those of the injection molding machine 10A of the first embodiment, and therefore, the same reference numerals are given to the same parts as those of the first embodiment, and the description will be omitted.
[0042]
In the injection molding machine 10C, the barrel base 21 and the barrel base 42 are separated from each other, and the barrel base 13 and the barrel 14 are maintained at a predetermined relative distance by the barrel moving mechanism 70 so that the barrel base 13 and the barrel 14 are maintained at a predetermined distance. 14 is driven in the axial direction. For this reason, the injection reaction force applied to the injection drive unit 41 during injection is not transmitted to the barrel 20, and the tip of the nozzle 25 is brought into close contact with the mold 11 with a relatively small nozzle touch force by the nozzle touch mechanism 30. Can be.
[0043]
5 and 6 show an injection molding machine 10D according to a fourth embodiment of the present invention. In the injection molding machine 10D, the fixed die plate 12 and the injection base 42 are connected to each other via the sub-frame 95 and the injection base moving mechanism 70. As an example, the front end of the sub-frame 95 is fixed to the fixed die plate 12, and the rear end of the sub-frame 95 is connected to the feed screw 73 of the ball screw devices 72a and 72b. Other configurations and operations are the same as those of the injection molding machine 10C according to the third embodiment, and therefore, the same reference numerals are given to the same parts as those in the third embodiment, and description thereof will be omitted.
[0044]
In practicing the present invention, in addition to the fixed die plate, the barrel unit, the nozzle touch mechanism, the injection unit, the injection base moving mechanism, and other components of the present invention are variously changed without departing from the scope of the present invention. It goes without saying that the present invention can be implemented in a modified form. The screw is not limited to the above embodiment, and for example, a twin screw or a cone-shaped screw can be used.
[0045]
【The invention's effect】
According to the present invention, the injection reaction force applied to the injection drive unit during injection is not transmitted to the barrel base or the barrel. Therefore, at the time of injection, the tip of the nozzle can be kept in close contact with the mold with a relatively small nozzle touch force by the nozzle touch mechanism. For this reason, the fixed die plate is prevented from being bent or deformed, and a stable nozzle touch force can be obtained. For example, even when the injection speed is high, the nozzle touch force becomes insufficient or unstable. Can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an injection molding machine showing a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of an injection molding machine showing a second embodiment of the present invention.
FIG. 3 is a front view of an injection molding machine showing a third embodiment of the present invention.
FIG. 4 is a plan view of the injection molding machine shown in FIG.
FIG. 5 is a front view of an injection molding machine showing a fourth embodiment of the present invention.
FIG. 6 is a plan view of the injection molding machine shown in FIG.
FIG. 7 is a sectional view showing a conventional injection molding machine.
[Explanation of symbols]
10A, 10B, 10C, 10D Injection molding machine 11 Mold 12 Fixed die plate 13 Barrel part 14 Injection part 20 Barrel X Axis 21 Barrel base part 22 Screw 25 Nozzle 30 Nozzle touch mechanism Reference numeral 41: injection driving unit 42: injection base unit 70: injection base moving mechanism 90: plunger

Claims (3)

A fixed die plate supporting the mold,
A barrel portion having a barrel disposed opposite to the fixed die plate and having a barrel base portion provided in the barrel,
A nozzle touch mechanism for moving the barrel portion in the axial direction of the barrel,
An injection unit having an injection drive unit for moving the screw or plunger inserted into the barrel in the axial direction and having an injection base unit provided in the injection drive unit,
An injection base moving mechanism that is connected to the fixed die plate and moves the injection unit in the axial direction according to the position of the barrel unit so that the barrel unit and the injection unit are maintained at a predetermined relative distance,
An injection molding machine comprising: The injection base moving mechanism,
A motor that moves the injection unit in the axial direction;
A sensor for detecting a relative position between the barrel unit and the injection unit,
A controller that controls rotation of the motor so that the barrel unit and the ejection unit are maintained at a predetermined relative position based on a signal output by the sensor,
The injection molding machine according to claim 1, further comprising: The nozzle touch mechanism,
A connecting member that connects the fixed die plate and the barrel base,
The injection molding machine according to claim 1, further comprising: a nozzle touch drive source that moves the connecting member in the axial direction.

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