JP3007485B2 - Injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding machine for injection-molding a molten resin using a mold, and a mold clamping pressure capable of obtaining a proper mold opening amount when the molten resin is injected into a cavity. The present invention relates to an injection molding machine having a function of automatically setting.

[0002]

2. Description of the Related Art Conventionally, various injection molding machines for injection molding a molten resin using a mold have been known. In these injection molding machines, it is necessary to set the opening amount of the mold at the time of molding to an appropriate value in accordance with the size and type of each molded product in order to produce molded products of good quality. In order to maintain the mold opening amount against the injection pressure of molten resin into the cavity, etc.,
It is required that the mold clamping pressure be set to an appropriate value. Also,
By setting the mold clamping pressure to an appropriate value, deformation of the mold and reduction in energy efficiency due to the application of excessive mold clamping pressure are also prevented.

[0003]

Although the proper value of the mold clamping pressure can be calculated from the cavity cross-sectional area and the injection pressure of the heating cylinder, it is necessary to accurately calculate the temperature of the molten resin, the inner diameter of the injection nozzle, the injection nozzle. It is necessary to use various numerical values such as the pore diameter as calculation elements. For this reason, the calculation becomes complicated, and it is difficult to accurately determine an appropriate value of the mold clamping pressure.

Therefore, the present invention can automatically set an appropriate mold clamping pressure, and can prevent the deterioration of the quality of a molded product due to an insufficient or excessive mold clamping pressure and a problem occurring in an injection molding machine.
Moreover, an object of the present invention is to provide an injection molding machine having good energy efficiency.

[0005]

In order to solve this problem, the resin injection device of the present invention has the following configuration. That is, as exemplified in FIG. 4, the injection molding machine of the present invention includes a fixed plate having a fixed relative position, and the fixed plate which is installed opposite to the fixed plate and moves back and forth along the axial direction. And a movable plate capable of changing its relative position, a fixed die attached to the fixed plate, and a movable die attached to the movable plate opposite to the fixed die. A molding die for forming a cavity between the joining surfaces when the fixed die and the movable die are joined by moving forward, and a mold clamping ram connected to a side of the movable plate opposite to the fixed plate. The movable platen is driven forward and backward via the mold clamping ram in accordance with supply and discharge of hydraulic oil to close and open the mold, and when the mold is closed, the movable mold is clamped to the movable mold via the clamping ram. A mold clamping cylinder capable of clamping by applying pressure and an injection nozzle at the tip end for melting the molten resin into the cavity. A mold opening input means for inputting a set distance between the movable mold and the fixed mold as a set mold opening, wherein the movable mold and the movable mold and Mold opening amount detecting means for detecting a distance between fixed molds as a mold opening amount, hydraulic pressure controlling means for controlling oil pressure in the mold clamping cylinder according to the detected mold opening amount, and Hydraulic pressure detecting means for detecting the mold clamping hydraulic pressure, and the mold clamping cylinder detected by the hydraulic pressure detecting means when the mold opening detected by the mold opening detecting means coincides with the set mold opening. Storage means for storing the mold clamping oil pressure as a set mold clamping oil pressure, and extracting the value of the set mold clamping oil pressure from the storage means and changing the mold clamping oil pressure in the mold clamping cylinder according to the extracted value. Mold clamping oil pressure control means for controlling to the set mold clamping oil pressure; Characterized by providing.

[0006]

In the injection molding machine having the above construction, first, the set distance between the movable mold and the fixed mold is inputted as the set mold opening by the mold opening input means. Subsequently, when injection molding for setting the mold clamping oil pressure is started, the mold opening detecting means detects the distance between the movable mold and the fixed mold as the mold opening. The hydraulic control means controls the hydraulic pressure in the mold clamping cylinder according to the detected mold opening. The oil pressure detecting means detects a mold clamping oil pressure in the mold clamping cylinder. When the mold opening detected by the mold opening detecting means matches the set mold opening, the storage means stores the detected mold clamping oil pressure as the set mold clamping oil pressure. Thus, the mold clamping oil pressure according to the set mold opening amount is detected and stored as the set mold clamping oil pressure, so that an appropriate mold clamping oil pressure according to the set mold opening amount can be automatically obtained.

[0007] Thereafter, the mold clamping oil pressure control means extracts the value of the set mold clamping oil pressure from the storage means and controls the mold clamping oil pressure in the mold clamping cylinder to the set mold clamping oil pressure according to the extracted value. Therefore, since the subsequent injection molding is clamped with the proper set clamping hydraulic pressure, the amount of mold opening of the molding die becomes a proper value, and a molded product of good quality can be obtained. In addition, it is possible to prevent problems caused by insufficient or excessive mold clamping pressure. In addition, energy efficiency is improved because excessive mold clamping oil pressure is prevented.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a preferred embodiment will be described with reference to the drawings to further clarify the present invention. First, the configuration of the resin injection device 10 of the present embodiment will be described. As shown in FIG. 1, a heating cylinder 12 capable of melting and injecting resin supplied from a resin supply device (not shown) is disposed at an end in the direction of arrow X in the drawing. At the end of the heating cylinder 12 in the direction of the arrow X, an injection cylinder 14 for applying an injection pressure to the molten resin in the heating cylinder 12 is provided. Further, an injection nozzle 16 serving as a molten resin injection path is provided at an end of the heating cylinder 12 opposite to the injection cylinder 14.

The fixed platen 18 is moved in the direction of the arrow Y of the heating cylinder 12.
Is arranged. A nozzle insertion hole 20 through which the injection nozzle 16 can be inserted is formed in the center of the fixed platen 18. Further, on the fixed platen 18, on the side opposite to the heating cylinder 12,
A fixed mold 22 is attached. This fixed mold 22
Has an injection hole 24 through which the molten resin can pass along the central axis.
Is provided. Further, a nozzle contact portion 26 which is a substantially hemispherical recess communicating with the injection hole 24 is provided on the fixed plate 18 side of the fixed mold 22. When the heating cylinder 12 is reciprocated by a hydraulic cylinder (not shown) and moves in the direction of the arrow Y, the heating cylinder 12
The injection nozzle 16 at the tip can be brought into close contact. further,
The injection hole 24 is also opened on the side opposite to the nozzle contact portion 26, and a circular fixed side cavity surface 28 is provided around the opening coaxially with the opening.

A movable mold 30 is disposed on the opposite side of the fixed mold 22 from the fixed platen 18 so as to face the fixed mold 22. The movable mold 30 is provided with a circular movable cavity surface 32 at a position corresponding to the fixed cavity surface 28. The movable mold 30 and the fixed mold 22 form the molding mold 3.
4 and the fixed-side cavity surface 28 and the movable-side cavity surface 32 provided on both the dies 22 and 30.
And can form the cavity 36.

The movable mold 30 is mounted on a movable plate 38. Further, the movable plate 38 has a cylindrical mold clamping ram 40.
Are connected. The other end of the mold clamping ram 40 is inserted through a mold clamping cylinder 42. The mold clamping cylinder 42 has a pair of oil chambers 46a and 46b separated by a piston 44 connected to an end of the mold clamping ram 40 inside the mold clamping cylinder 42.

The above-described heating cylinder 12 to mold clamping cylinder 46 are installed on a base not shown. A plurality of stays (not shown) having both ends secured to the fixed platen 18 and the mold clamping cylinder 42 are inserted through the outer edge of the movable platen 38, and the movable platen 38 can accurately move along the stays. By moving back and forth, the relative position with respect to the fixed plate 18 can be changed.

Each of the oil chambers 46a, 46
b is provided with a pair of oil nozzles 48a and 48b communicating with the hydraulic oil supply / discharge passage 5 in each of the oil nozzles 48a and 48b.
0a and 50b are connected. This hydraulic oil supply / discharge path 50
A and 50b are connected to a hydraulic oil supply passage 54a via an electromagnetic directional control valve 52, and a recovery tank 56 for collecting hydraulic oil discharged via the electromagnetic directional control valve 52 is provided. The hydraulic oil supply / discharge path 50a has a hydraulic pressure sensor 58
Is installed, and the hydraulic pressure of the hydraulic oil supply / discharge passage 50a can be detected. The oil pressure sensor 58 is electrically connected to a control unit 60 that executes various controls, and outputs a signal corresponding to the oil pressure detected by the oil pressure sensor 58 to the control unit 6.
0 can be entered. The details of the control unit 60 will be described later. The hydraulic oil supply path 54 a is connected to a hydraulic pump 62, and the hydraulic pump 62 can be supplied with hydraulic oil from a hydraulic oil tank 64. Further, an electromagnetic relief valve 68 is connected to the hydraulic oil supply passage 54a via a branch passage 66. The drain from the electromagnetic relief valve 68 can be collected in the collection tank 70.

With this configuration, hydraulic oil at a predetermined pressure can be supplied from the hydraulic pump 62 to the hydraulic oil supply passage 54 a, and the supplied hydraulic oil is supplied to the oil chamber of the mold closing cylinder 42 through the electromagnetic directional control valve 52. By controlling the supply / discharge to 46a, 46b, the mold clamping ram 40, the movable plate 38 and the movable mold 30 can be driven forward and backward in the arrow X direction and the arrow Y direction, and the movable mold 30 can be moved in the arrow X direction. The mold can be clamped at a desired mold clamping pressure by pressing along the line. On the other hand, a hydraulic oil supply path 54b is connected to the hydraulic pump 62, and hydraulic oil can be supplied to and discharged from the injection cylinder 14 of the heating cylinder 12 via a hydraulic oil supply / discharge mechanism and a hydraulic oil supply / discharge path 72 (not shown). It is.

On the other hand, the movable mold 30 is provided with a mold opening sensor 74 capable of detecting a distance from the fixed mold 22 as a mold opening amount and outputting a signal corresponding to the detected value. The signal from the mold opening sensor 74 is input to the comparator 78 via the amplifier 76. A signal from the control unit 60 can be input to the comparator 78. The comparator 78 can receive a signal from the mold opening sensor 74 and a signal from the control unit 60 and output a signal corresponding to a difference between the two inputs. The output signal from the comparator 78 is input to the control unit 60, and a signal from the control unit 60 can be input to the electromagnetic relief valve 68 via the amplifier 80 as a control signal.

Here, the control unit 60 will be described. As shown in FIG. 2, the control unit 60 includes a display panel 60a and an operation panel 60b, and incorporates a known microcomputer (not shown). Through the operation panel 60b, it is possible to input a set distance between the movable mold 30 and the fixed mold 22 as a set mold opening amount and other various instructions to the control unit. Further, it is possible to execute a control process according to an input instruction or a program stored in the microcomputer in advance. Further, input contents, execution contents, and data from instruments such as a hydraulic sensor can be displayed on the display panel 60a. Although not shown, the electromagnetic direction control valve 52 and other hydraulic devices can be controlled by an instruction from the control unit 60.

The control process executed by the control unit 60 during the automatic setting operation of the mold clamping pressure will be described below with reference to FIG. Prior to the automatic clamping pressure setting operation, the mold opening sensor 74 is set to zero. When an automatic clamping pressure setting mode is selected on the operation panel 60b and a start instruction is input, a routine set as the automatic clamping pressure setting mode is started.

First, the set mold opening A is input by the operator (step 210). When the set mold opening A is input, an instruction to increase the mold clamping pressure is issued (step 220). At this time, the mold clamping pressure is increased by an oil pressure corresponding to, for example, about 80% of the maximum mold clamping force. Subsequently, an injection start is instructed (step 230). When the injection is started under the injection molding conditions of the molded article, the measurement of the mold opening a is automatically started (step 240). When the mold opening a is input from the mold opening sensor 74, it is determined whether the mold opening a is equal to the set mold opening A (step 250). At this time, if the value of a with respect to A is within the set tolerance, A = a
Is considered. If the comparison result is A ≠ a, A> a is determined (step 260). If A> a, an instruction is issued to decrease the mold clamping oil pressure (step 270). If not A> a, an instruction to increase the mold clamping hydraulic pressure is issued (step 28).
0). After executing Step 270 or Step 280, the process returns to Step 250 again, and repeats Step 260 to Step 270 or Step 28 until A = a.
Repeat 0. If A = a in the comparison in step 250, the mold clamping oil pressure detected by the oil pressure sensor 58 at this time is stored as the set mold clamping oil pressure (step 290). Thereafter, the measurement of the mold opening a is terminated (step 300). Further, it is determined whether or not there is an instruction for injection molding in a normal operation (step 310). If it is determined that there is an instruction for normal operation, normal operation is performed with the mold clamped at the set mold hydraulic pressure stored in step 290 (step 320). After executing step 320, or when it is determined in step 310 that there is no instruction for normal operation, the mold clamping pressure automatic setting routine ends.

Next, a description will be given of a case in which the mold clamping pressure automatic setting operation is performed in the injection molding machine having the above-described configuration. Prior to the automatic mold clamping pressure setting operation, the operator performs zero point setting of the mold opening amount sensor 74. First,
The start of the mold clamping pressure automatic setting mode is instructed via the operation panel 60b, and the set mold opening A is input. Also, a signal corresponding to the set mold opening A is sent from the control unit 60 to the comparator 7.
8 is input. Subsequently, the electromagnetic direction control valve 52 is operated so that hydraulic oil is supplied to the oil chamber 46a of the mold clamping cylinder 42 and discharged from the oil chamber 46b. As a result, the movable mold 30 is advanced along the direction of the arrow X in FIG. 1, so that the molding mold 34 is closed and clamped. When the molding die 34 is clamped to form the cavity 36, the heating cylinder 12 moves along the arrow Y direction in FIG. 1 to bring the injection nozzle 16 into close contact with the nozzle contact portion 26. Subsequently, hydraulic oil is supplied to the injection cylinder 14 to generate a set injection pressure, so that injection of the molten resin by the injection pressure is started. The injected molten resin flows into the cavity 36 via the injection hole 24. In accordance with the inflow of the molten resin,
An internal pressure corresponding to the injection pressure is generated. This cavity 36
The inner pressure acts in a direction to open the molding die 34. Therefore, the molding die 34 is opened according to the difference between the mold clamping pressure applied from the mold clamping cylinder 42 and the internal pressure of the cavity 36. Then, the mold opening sensor 7 detecting the mold opening a
4 is input to the comparator 78 via the amplifier 76. A signal corresponding to the set mold opening A and a signal corresponding to the mold opening a are compared by the comparator 78. When A> a, the comparison output S is reduced. When A <a, the comparison output S is reduced. Increase, A = a
In this case, the comparison output S is not changed. The comparison output S from the comparator 78 is input from the control unit 60 to the electromagnetic relief valve 68 via the amplifier 80. When the comparison output S increases, the position of the electromagnetic relief valve 68 moves in the valve closing direction, and when the comparison output S decreases, the position of the electromagnetic relief valve 68 moves in the valve opening direction. The pressure of the hydraulic oil supplied to 46a is controlled to increase or decrease. The increase / decrease in the pressure of the working oil to the oil chamber 46a causes the mold clamping pressure of the molding die 34 to increase / decrease, and the mold opening a changes accordingly. When the set mold opening A is equal to the mold opening a due to the change in the mold opening a, the mold clamping oil pressure detected by the hydraulic pressure sensor 58 is stored in the control unit 60 as the set mold clamping oil pressure. As a result, the set mold hydraulic pressure is automatically set, but the set mold hydraulic pressure set in this way is
This is an appropriate value corresponding to the set mold opening. However, a pressure of + α can be added to cope with the repetition error of the hydraulic equipment. Further, the setting of the set mold clamping oil pressure does not require experiments or complicated calculations for the setting.

When the set mold clamping oil pressure is automatically set as described above, the measurement of the mold opening a is terminated. Subsequently, when performing the injection molding by the normal operation, since the molding die is clamped by the set clamping hydraulic pressure stored above, the mold opening amount a
Exactly matches the set mold opening A. For this reason, molding with an inappropriate mold opening amount due to insufficient or excessive mold clamping pressure is prevented, and the quality of the molded product is improved. In addition, problems that occur in the injection molding machine mainly due to excessive mold clamping pressure are also prevented. No burrs are generated, only gas in the resin escapes, and energy efficiency is improved.

When the operation of automatically setting the set mold clamping oil pressure is completed, the mold opening sensor 74 may be removed from the injection molding machine 10.

[0022]

As described above, according to the injection molding machine of the present invention, an appropriate mold clamping pressure can be automatically set, and the quality of a molded product is deteriorated due to insufficient or excessive mold clamping pressure. And an injection molding machine can be prevented, and energy efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of an injection molding machine according to an embodiment.

FIG. 2 is an explanatory diagram of a control unit of the injection molding machine according to the embodiment.

FIG. 3 is a flowchart illustrating a control process of a control unit in a mold clamping pressure automatic setting operation of the injection molding machine according to the embodiment.

FIG. 4 is a block diagram illustrating an injection molding machine of the present invention.

[Description of Signs] 10 ... resin injection device, 12 ... heating cylinder, 16 ...
・ Injection nozzle, 18 ・ ・ ・ Fixed plate, 22 ・ ・ ・ Fixed mold, 24 ・ ・ ・ Injection hole, 30 ・ ・ ・ Movable mold, 34 ・ ・
Molding die, 36 cavity, 38 movable plate, 40 clamping ram, 42 clamping cylinder, 4
6a, 46b ... oil chamber, 52 ... electromagnetic directional control valve,
58 ... oil pressure sensor, 60 ... control unit, 68
... Electromagnetic relief valve, 74 ... Type opening amount sensor, 78
... Comparator.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 45/00-45/84 B29C 33/00-33/76

Claims (1)

(57) [Claims] A fixed plate having a fixed relative position, a movable plate installed opposite to the fixed plate and capable of moving back and forth along an axial direction to change a relative position with respect to the fixed plate; A fixed mold attached to a fixed platen and a movable mold attached to the movable plate opposite to the fixed mold, wherein the movable mold moves forward and the fixed mold and the movable mold are A molding die for forming a cavity between the joining surfaces when joined, a mold clamping ram connected to a side of the movable plate opposite to the fixed platen, and a mold clamping ram corresponding to supply and discharge of hydraulic oil. A mold clamping cylinder capable of moving the movable platen forward and backward through a ram to close and open the mold and applying a mold clamping pressure to the movable mold via the mold clamping ram when the mold is closed; Molding machine having a heating cylinder having an injection nozzle in its section and capable of injecting molten resin into the cavity A mold opening input means for inputting a set distance between the movable mold and the fixed mold as a set mold opening; and a mold for detecting a distance between the movable mold and the fixed mold as a mold opening. Opening amount detecting means, hydraulic pressure controlling means for controlling the oil pressure in the mold clamping cylinder according to the detected mold opening amount, oil pressure detecting means for detecting the mold clamping oil pressure in the mold clamping cylinder, and the mold Storage means for storing a mold clamping oil pressure in the mold clamping cylinder detected by the oil pressure detecting means when the mold opening amount detected by the opening amount detecting means coincides with the set mold opening amount as a set mold clamping oil pressure. And clamping hydraulic pressure control means for extracting the value of the set clamping pressure from the storage means and controlling the clamping pressure in the clamping cylinder to the setting clamping pressure in accordance with the extracted value. An injection molding machine characterized by being provided.