KR20130079223A - Injection molding machine - Google Patents

Abstract

PURPOSE: An injection molding machine is provided to reduce power consumption for a mold opening operation by performing the mold opening operation with a mold opening and closing driver so that the mold opening operation is performed in a condition which a clamping force is low when the clamping force which is less than a predetermined value is detected by a clamping force monitoring unit. CONSTITUTION: An injection molding machine comprises a mold opening and closing driver (linear motor), a mold driver (electromagnet), and a control unit (60). The mold opening and closing driver drives a mold opening operation. The mold driver drives a mold operation. The control unit controls an operation of the mold opening and closing driver and an operation of the mold driver. The control unit includes a clamping force monitoring unit (64) monitoring whether a clamping force is less than a predetermined value when removing the clamping force. The mold opening operation is performed by the mold opening and closing driver when the clamping force is detected to be less than the predetermined value by the clamping force monitoring unit.

Description

Injection molding machine

This application claims priority based on Japanese Patent Application No. 2011-284098 for which it applied on December 26, 2011. The entire contents of that application are incorporated by reference in this specification.

The present invention relates to an injection molding machine.

The injection molding machine molds a molded article by filling molten resin in the cavity space of the mold apparatus and solidifying it. The mold apparatus comprises a stationary mold and a movable mold, and a cavity is formed between the stationary mold and the movable mold at the time of mold clamping. The mold closing, mold clamping, and mold opening of the mold apparatus are performed by a mold clamping apparatus. As a mold clamping device, it is proposed to include a mold opening / closing driving unit (for example, a linear motor) for driving a mold opening and closing operation, and a mold clamping unit (for example, an electromagnet) for driving a mold opening and closing operation (see Patent Document 1, for example).

WO 05/090052 Pamphlet

When releasing the clamping force before opening, the clamping force does not immediately drop to zero (0) due to the influence of the response delay of the clamping driver. Therefore, the control part may perform a mold opening instruction in the state with high clamping force. When the mold opening instruction is executed in a state where the clamping force is high, the power consumption for the mold opening operation is increased, or the mold opening operation becomes unstable.

The present invention has been made in view of the above problems, and an object thereof is to provide an injection molding machine which can reduce power consumption for mold opening operation and can stabilize mold opening operation.

According to an aspect of the present invention, there is provided an injection molding machine comprising:

Mold opening and closing drive unit for driving the mold opening and closing operation,

A mold driving part for driving the mold movement;

And a control unit for controlling the operation of the mold opening / closing drive unit and the operation of the mold driving unit.

The control unit includes a clamp force monitoring unit for monitoring whether the clamp force is lower than or equal to a predetermined value when releasing the clamp force, and the mold opening / closing drive unit is operated by the mold opening / closing drive unit when the clamp force is detected by the clamp force monitoring unit. It is characterized by performing.

According to the present invention, the power consumption for the mold opening operation can be reduced, and an injection molding machine capable of stabilizing the mold opening operation is provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the state at the time of mold closing and mold clamping of the injection molding machine which concerns on one Embodiment of this invention.
Fig. 2 is a view showing the mold starting state of the injection molding machine according to one embodiment of the present invention. Fig.
3 is a view showing a control system of an injection molding machine according to an embodiment of the present invention.
Fig. 4 is a first diagram showing the change over time of the supply current to the coil of the electromagnet and the change of the clamp force by the electromagnet over time.
FIG. 5 is a second diagram showing the change over time of the supply current to the coil of the electromagnet and the change of the clamp force by the electromagnet over time.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and a description thereof will be omitted. Further, the moving direction of the movable platen when mold closing is referred to as the forward direction, and the moving direction of the movable platen when the mold opening is performed will be referred to as rear.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the state at the time of mold closing and the mold clamping of the injection molding machine which concerns on one Embodiment of this invention. In FIG. 1, the solid line shows the state at the time of mold closing, and the double-dot chain line shows the state at the time of mold clamping. Fig. 2 is a view showing a mold starting state of an injection molding machine according to an embodiment of the present invention. Fig.

In the drawing, reference numeral 10 denotes an injection molding machine, Fr denotes a frame of the injection molding machine 10, Gd denotes a guide consisting of two rails which are placed on the frame Fr, and 11 denotes a fixed platen. The stationary platen 11 may be provided on a position adjusting base Ba movable along a guide Gd extending in the mold opening and closing direction (left and right direction in the drawing). However, the stationary platen 11 may be placed on the frame Fr.

The movable platen 12 is disposed opposite to the stationary platen 11. [ The movable platen 12 is fixed on the movable base Bb and the movable base Bb is movable on the guide Gd. As a result, the movable platen 12 is movable in the mold opening / closing direction with respect to the stationary platen 11. [

The rear platen 13 is disposed at a predetermined distance from the stationary platen 11 and in parallel with the stationary platen 11. [ The rear platen 13 is fixed to the frame Fr through the leg portion 13a.

Between the stationary platen 11 and the rear platen 13, a tie bar 14 (only two of the four tie bars 14 in the figure) is provided as four connecting members. The stationary platen 11 is fixed to the rear platen 13 through the tie bar 14. [ The movable platen 12 is disposed so as to be movable forward and backward along the tie bar 14. [ A guide hole (not shown) for passing the tie bar 14 is formed at a position corresponding to the tie bar 14 in the movable platen 12. [ However, instead of the guide hole, a cutout may be formed.

(Not shown) is formed at the front end portion (right end portion in the drawing) of the tie bar 14 and the nut n1 is screwed to the threaded portion so that the front end portion of the tie bar 14 is fixed to the stationary platen 11). The rear end portion of the tie bar 14 is fixed to the rear platen 13.

A stationary mold 15 is mounted on the stationary platen 11 and a movable mold 16 is mounted on the movable platen 12. The stationary mold 15 and the movable mold 12 16 are connected and disconnected, and mold closing, mold clamping, and mold clamping are performed. However, as the mold clamping is performed, a cavity space (not shown) is formed between the stationary mold 15 and the movable mold 16, and the molten resin is filled in the cavity space. The mold apparatus (19) is constituted by the stationary mold (15) and the movable mold (16).

The attracting plate 22 is disposed in parallel with the movable platen 12. [ The attracting plate 22 is fixed to the slide base Sb via the mounting plate 27 and the slide base Sb can travel on the guide Gd. As a result, the attracting plate 22 can move forward and backward from the rear platen 13. The attracting plate 22 may be formed of a magnetic material. However, the mounting plate 27 may be omitted, and in this case, the suction plate 22 is directly fixed to the slide base Sb.

The rod 39 is connected to the attracting plate 22 at the rear end and connected to the movable platen 12 at the front end. Thus, the rod 39 is advanced as the adsorption plate 22 advances at the time of mold closing, advances the movable platen 12, and is retracted as the adsorption plate 22 is retreated at the mold start, . Thereby, a rod hole 41 for passing the rod 39 is formed in the central portion of the rear platen 13.

The linear motor 28 is a mold opening and closing drive part for moving the movable platen 12 forward and backward and is disposed between the frame Fr and the attraction plate 22 connected to the movable platen 12, for example. However, the linear motor 28 may be disposed between the movable platen 12 and the frame Fr.

The linear motor 28 includes a stator 29 and a mover 31. The stator 29 is formed on the frame Fr in parallel with the guide Gd and in correspondence with the movement range of the slide base Sb. The movable element 31 is opposed to the stator 29 at the lower end of the slide base Sb and is formed over a predetermined range.

The mover (31) has a core (34) and a coil (35). The core 34 is provided with a plurality of magnetic pole teeth 33 protruding toward the stator 29 at a predetermined pitch and the coils 35 are wound around the magnetic pole teeth 33, Lt; / RTI > However, the magnetic pole teeth 33 are formed parallel to each other in a direction perpendicular to the moving direction of the movable platen 12. [ Further, the stator 29 has a core (not shown) and a permanent magnet (not shown) extending on the core. The permanent magnet is formed by alternately magnetizing the magnetic poles of the N pole and the S pole. And a position sensor 53 for detecting the position of the mover 31 is disposed.

When the linear motor 28 is driven by supplying a predetermined current to the coil 35 of the linear motor 28, the mover 31 is moved forward and backward. As a result, the suction plate 22 and the movable platen 12 are advanced and retreated to perform mold closing and mold opening. The linear motor 28 is feedback-controlled based on the detection result of the position sensor 53 so that the position of the mover 31 becomes a set value.

However, in this embodiment, the permanent magnet is disposed in the stator 29 and the coil 35 is disposed in the mover 31, but a coil may be disposed in the stator and a permanent magnet may be disposed in the mover. In this case, since the coil does not move as the linear motor 28 is driven, wiring for supplying electric power to the coil can be easily performed.

However, instead of the linear motor 28, a ball screw mechanism or a fluid pressure cylinder such as a hydraulic cylinder or an air pressure cylinder may be used for converting the rotational motion of the rotary motor and the rotary motor into linear motion.

The electromagnet unit 37 generates an attraction force between the rear platen 13 and the attracting plate 22. [ This attraction force is transmitted to the movable platen 12 through the rod 39 so that a clamping force is generated between the movable platen 12 and the fixed platen 11. [

However, the clamping device is constituted by the fixed platen 11, the movable platen 12, the rear platen 13, the suction plate 22, the linear motor 28, the electromagnet unit 37, the rod 39 and the like. do.

The electromagnet unit 37 is composed of an electromagnet 49 as a mold clamping portion formed on the side of the rear platen 13 and an attracting portion 51 formed on the attracting plate 22 side. The attracting portion 51 surrounds the rod 39 on a predetermined portion of the attracting surface (front end surface) of the attracting plate 22, for example, the attracting plate 22, . A groove 45 for accommodating the coil 48 of the electromagnet 49 is formed around a predetermined portion of the attracting surface (rear end surface) of the rear platen 13, for example, around the rod 39. The core 46 is formed on the inner side of the groove 45. The coil 48 is wound around the core 46. [ A yoke 47 is formed on a portion of the rear platen 13 other than the core 46.

In this embodiment, however, the electromagnet 49 is formed separately from the rear platen 13, and the attracting portion 51 is formed separately from the attracting plate 22. However, as the portion of the rear platen 13, , And the adsorption portion may be formed as a part of the adsorption plate (22). The arrangement of the electromagnet and the adsorption portion may be reversed. For example, the electromagnet 49 may be provided on the adsorption plate 22 side and the adsorption unit 51 may be formed on the rear platen 13 side. The number of the coils 48 of the electromagnet 49 may be plural.

In the electromagnet unit 37, when an electric current is supplied to the coil 48, the electromagnet 49 is driven, and the attracting portion 51 is attracted to generate a mold clamping force.

3 is a view showing a control system of an injection molding machine according to an embodiment of the present invention. The control unit 60 includes, for example, a CPU and a memory, and controls the operation of the linear motor 28 and the electromagnet 49 by processing the control program recorded in the memory by the CPU.

The control unit 60 includes a mold opening and closing processing unit 61 for controlling the operation of the linear motor 28 and a mold processing unit 62 for controlling the operation of the electromagnet 49.

The mold opening and closing processing unit 61 outputs a signal indicating a current supplied to the coil 35 of the linear motor 28 to the linear motor current supply unit 71. The current supply unit 71 for the linear motor is configured by, for example, an inverter including a plurality of power modules. The current supply unit 71 for the linear motor supplies a current according to the signal supplied from the mold opening and closing processing unit 61 to the coil 35 of the linear motor 28. The DC power supply 80 is connected to the current supply unit 71 for the linear motor. The DC power supply 80 is composed of a rectifier 82 such as a diode for converting the AC current of the AC power supply 90 into a DC current and a capacitor 84 for smoothing the DC current outputted from the rectifier 82.

The mold processing unit 62 outputs a signal indicating a current supplied to the coil 48 of the electromagnet 49 to the electromagnet current supply unit 72. The electric current supplied to the coil 48 of the electromagnet 49 is feedback-controlled based on the detection value of the clamping force sensor (for example, deformation sensor 55) mentioned later so that clamping force may become a target value. The electromagnet current supply unit 72 is configured by, for example, an inverter including a plurality of power modules. The electromagnet current supply unit 72 supplies the current according to the signal supplied from the mold processing unit 62 to the coil 48 of the electromagnet 49. The electromagnet current supply unit 72 has a function of changing the direction and directivity (size) of the direct current flowing through the coil 48 of the electromagnet 49. The DC power supply 80 is connected to the electromagnet current supply unit 72.

The control unit 60 further includes a clamping force monitoring unit 64 for monitoring whether the clamping force is equal to or less than a predetermined value when releasing the clamping force. For example, the clamping force monitoring unit 64 monitors whether the clamping force is equal to or less than a predetermined value based on the detected value of the clamping force sensor for detecting the clamping force. As the clamping force sensor, for example, a strain sensor 55 for detecting the deformation (extension amount) of the tie bar 14 which is extended in accordance with the clamping force is used. Since the deformation of the tie bar 14 decreases as the clamp force decreases, it is determined whether the clamp force is equal to or less than the predetermined value based on whether the deformation of the tie bar 14 is equal to or less than the predetermined value. As the clamp force sensor, instead of the deformation sensor 55, a load sensor such as a load cell that detects the load applied to the rod 39 and a magnetic sensor that detects the magnetic field of the electromagnet 49 may be used. It may vary. For example, the strain sensor is applicable not only to the tie bar 14 but also to the rod 39. This is because the deformation (reduction amount) of the rod 39 is proportional to the mold clamping force. In addition, the clamping force monitoring unit 64 may monitor whether or not the clamping force is equal to or less than a predetermined value based on the difference (distance difference) of the position from the position at the time of closing the predetermined member. As the clamping force decreases, the difference in position decreases. Therefore, it is determined whether the clamping force is lower than or equal to the predetermined value based on whether the difference in position is lower than or equal to the predetermined value. The predetermined member may be a member whose position is shifted with the extension of the tie bar 14. Examples of the member include the stationary platen 11, the movable platen 12, the suction plate 22, and the mover 31 of the linear motor 28. For example, the position difference of the movable element 31 can be detected by the position sensor 53. FIG. In order to improve the reliability, the clamping force monitoring unit 64 may monitor whether the clamping force is equal to or less than a predetermined value based on both the detected value of the clamping force sensor and the difference in position.

Next, the operation of the injection molding machine 10 having the above-described configuration will be described. Various operations of the injection molding machine 10 are performed under the control of the control unit 60. [

The control unit 60 controls the mold closing process by the mold opening and closing processing unit 61. The mold opening / closing processing section 61 supplies current to the coil 35 of the linear motor 28 in the state of FIG. 2 (state of mold opening) to advance the movable platen 12. As shown in FIG. 1, the movable mold 16 abuts the fixed mold 15. At this time, a gap? 0 is formed between the rear platen 13 and the attracting plate 22, that is, between the electromagnet 49 and the attracting portion 51. However, the force required for mold closing is sufficiently small compared with the mold clamping force.

Subsequently, the control unit 60 controls the molding process by the mold processing unit 62. The mold processing part 62 supplies a direct current to the coil 48 of the electromagnet 49, and sucks the adsorption part 51 to the electromagnet 49. This attraction force is transmitted to the movable platen 12 through the rod 39 so that a clamping force is generated between the movable platen 12 and the fixed platen 11. [ Since the tie bar 14 is elastically stretched in proportion to the clamping force, the fixed platen 11, the movable platen 12, the suction plate 22, and the linear motor 28, as indicated by the double-dotted line in FIG. 1. Mover 31 is slightly advanced. The gap δ1 formed between the rear platen 13 and the suction plate 22 at the time of mold clamping is smaller than the gap δ0 at the time of mold closing.

The molten resin is filled in the cavity space of the mold apparatus 19 in the mold state. When the resin is cooled and solidified, the mold clamping unit 62 adjusts the current supplied to the coil 48 of the electromagnet 49 to release the clamping force. As the tie bar 14 is elastically restored with the release of the clamping force, the movable mold 16, the suction plate 22, and the mover 31 of the linear motor 28 retreat slightly.

Subsequently, the control unit 60 controls the mold opening process by the mold opening and closing processing unit 61. The mold opening and closing processing unit 61 supplies a current to the coil 35 of the linear motor 28 to retreat the movable platen 12. As shown in Fig. 2, the movable mold 16 is retracted to be molded.

By the way, in the clamping process, when releasing the clamping force, the clamping force does not immediately drop to 0 (zero) under the influence of the response delay of the electromagnet 49. The response delay of the electromagnet 49 is caused by the influence of magnetism remaining on the electromagnet 49 (for example, the core 46 and the like).

Therefore, the mold opening / closing processing unit 61 prohibits the mold opening operation until the clamping force monitoring unit 64 detects that the clamping force is lower than or equal to the predetermined value, and when the clamping force monitoring unit 64 detects that the clamping force is lower than or equal to the predetermined value. The current is supplied to the linear motor 28 to perform the mold opening operation. Therefore, since the mold opening operation is performed in a state where the mold clamping force is low, the power consumption for the mold opening operation can be reduced, and the mold opening operation can be stabilized.

Next, based on FIG. 4, the clamping force release process by the mold clamping part 62 is demonstrated. The following processing is performed before mold opening after applying a predetermined clamping force to the mold apparatus 19.

4 (a) shows the change over time of the supply current to the coil of the electromagnet, and FIG. 4 (b) shows the change over time of the clamp force by the electromagnet. 4, the broken line when setting the current value at time (t ₀₎ to 0, the solid line when sikyeoteul reverse the direction of the current in time (t _0), one-dot chain line when keeping the current value at time (t ₁₎ Each case is shown. In any case, the mold clamping unit 62 generates a predetermined clamping force P ₀ by supplying a constant DC current I ₀ to the coil 48 of the electromagnet 49 until time t ₀ . (The data up to the time t ₀ in FIG. 4 only shows a broken line).

When releasing the predetermined clamping force P ₀ , the mold clamping unit 62 cuts off the supply current to the coil 48 of the electromagnet 49 at time t ₀ , as indicated by broken lines in FIG. 4A. You may also Since the current does not flow in the coil 48 of the electromagnet 49 after the time t ₀ , the clamping force decreases slowly due to the influence of the response delay of the electromagnet 49 as indicated by the broken line in FIG. 4 (b). . The response delay of the electromagnet 49 is caused by the influence of magnetism remaining on the core 46 and the like of the electromagnet 49.

Further, when releasing the predetermined clamping force P ₀ , the mold clamping unit 62 reverses the direction of the DC current at time t ₀ as indicated by the solid line in FIG. The DC current I _{1 in} the direction opposite to the direction in which P ₀ ) is generated may flow through the coil 48 of the electromagnet 49. The magnetic field in the direction of canceling the magnetic field remaining in the electromagnet 49 is formed, and as shown by the solid line in FIG. Therefore, the waiting time until mold opening can be shortened.

The larger the intensity (size) of the reverse DC current I ₁ , the shorter the waiting time until mold opening. The shorter this waiting time is, the higher the production efficiency is, while the lowering of the clamping force is faster, and the fluctuation of the load on the mold apparatus 19 or the like becomes sharper. Therefore, the strength of the reverse DC current I ₁ is determined in advance by a test or the like in consideration of both the production efficiency and the variation in the load applied to the mold apparatus 19 and the like. In addition, the strength of the reverse DC current I ₁ may be determined based on the strength of the DC current I _{0 at} the time of generating the predetermined clamping force P ₀ .

By the way, when the time for flowing the direct current (I ₁ ) in the reverse direction becomes long, the electromagnet 49 and the adsorption portion 51 are resorbed, so that the clamping force is increased again as indicated by the dashed-dotted line in FIG. . However, it is presumed that the clamping force is increased again before returning to zero because the magnetic field remaining in the electromagnet 49 is nonuniform, and the timing at which the magnetic field is extinguished differs depending on the place.

Therefore, in order to suppress the increase of the clamping force, when the clamping force is released, the clamping force judgment unit 66 provided in the control unit 60 may determine whether the clamping force is within a predetermined range (Pmin to Pmax). This determination is performed based on the detected value of the deformation sensor 55 as the clamping force sensor, and / or the detected value (difference in position) of the position sensor 53, and may be repeated every predetermined time.

When the clamping force determination unit 66 determines that the clamping force is within a predetermined range, the clamping processing unit 62 may stop the current supply to the coil 48 of the electromagnet 49. The timing of stopping the supply of current to the coil 48 of the electromagnet 49 may be in the middle of re-increasing the clamping force, but is preferably in the middle of the lowering of the clamping force. Since the current does not flow through the coil 48 after the supply of the electromagnet 49 to the coil 48 is stopped, the clamping force decreases at a speed in accordance with the response delay of the electromagnet 49.

Next, based on FIG. 5, the modification of the clamping force release process by the mold clamping part 62 is demonstrated. The following processing is performed before mold opening after applying a predetermined clamping force to the mold apparatus 19.

FIG. 5 (a) shows the change over time of the supply current to the coil of the electromagnet, and FIG. 5 (b) shows the change over time of the clamp force by the electromagnet.

In the modification shown in FIG. 5, when releasing the predetermined clamping force P ₀ , the intensity of the direct current flowing through the coil 48 of the electromagnet 49 is gradually decreased from time t ₀ to time t _11. After zero, the direction of the direct current is changed to gradually increase the strength of the direct current. In this way, the DC current I _{11 in} the direction opposite to the direction in which the predetermined clamping force P ₀ is generated flows through the coil 48 of the electromagnet 49, and then to the coil 48 of the electromagnet 49 before mold opening. Reverses the direction of the flowing DC current one or more times. Each time the inversion, the maximum value of the intensity of the DC current may be set small (I ₁₁ > I ₁₂ > I ₁₃ > I ₁₄ > I ₁₅ ). The reversal timing t ₁₂ <t ₁₃ <t ₁₄ <t ₁₅ may be just before the resorption of the electromagnet 49 and the adsorption part 51 starts, that is, immediately before the increase in the clamping force starts.

In this way, by reversing the direction of the direct current flowing through the coil 48 of the electromagnet 49, the influence of the nonuniformity of the magnetic field remaining on the electromagnet 49 can be reduced, and the reduction of the clamp force can be further promoted, thereby producing The efficiency can be further improved.

In addition, when the current supply time is long and the clamping force is increased again, the clamping force can be lowered again by reversing the direction of the DC current flowing through the coil 48 of the electromagnet 49. Therefore, the freedom of pattern setting is high and control is easy.

As mentioned above, although one Embodiment of this invention etc. were demonstrated, this invention is not limited to said embodiment etc., Various deformation | transformation and substitution can be added to said embodiment etc., without deviating from the range of this invention. .

For example, even in the fourth example shown by the solid line, but reversing the direction of the DC current flowing through the coil 48 of the electromagnet 49 at time (t _0), the current supply to the time the electromagnet 49 at (t ₀₎ May be stopped once, a predetermined time is provided, and the reverse DC current I ₁ may be supplied to the coil 48 of the electromagnet 49.

10 Injection molding machine
15 stationary mold
16 Operation mold
28 Linear Motor (Type Opening and Closing Drive Part)
31 Motor of linear motor
35 coils of linear motor
48 Coils of electromagnets
49 Electromagnet (Mold Drive)
51 adsorption part
55 strain sensor
60 control unit
61 type opening /
The 62-
64 clamping force monitor
66 Criminal Judgment

Claims (3)

Mold opening and closing drive unit for driving the mold opening and closing operation,
A mold driving part for driving the mold movement;
Control unit for controlling the operation of the mold opening and closing drive unit, and the mold driving unit
And,
The control unit includes a clamp force monitoring unit for monitoring whether the clamp force is lower than or equal to a predetermined value when releasing the clamp force, and the mold opening / closing drive unit is operated by the mold opening / closing drive unit when it is detected that the clamp force is lower than or equal to a predetermined value. Doing
. Claim 1
The clamping force monitoring unit monitors whether the clamping force is equal to or less than a predetermined value based on the detection value of the clamping force sensor.
. The method according to claim 1 or 2,
The clamping force monitoring unit monitors whether or not the clamping force is equal to or less than a predetermined value based on a difference in position from a position at the time of closing of a predetermined member.
.

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