JP2623414B2 - Toggle type clamping force abnormality detection method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a method for detecting an abnormality in a toggle-type mold clamping force, in which when a crosshead of a toggle mechanism is driven, a mold is driven to open and close via a toggle link mechanism. It concerns the device.

[0002]

2. Description of the Related Art It is said that a mold is extremely important in molding technology, and the quality of a molded product depends on the mold. At the same time, the mold clamping machine is also an important factor. The mold clamping machine
A resin material is injected started known as the mold cavity until it cooled and solidified, it is requested to have a UNA clamping force by the mold is not opened by the pressure of the resin material of the mold or cavity Tightening force generation methods are roughly classified into toggle types and direct pressure types. As is well known, the toggle type mold clamping machine includes a crosshead, a cross link, a plurality of long and short toggle links, a tie bar, and the like. One of the toggle links is rotatably connected to a toggle receiving plate or an adjustment plate, and the other toggle link is rotatably connected to a movable plate by a pin. Therefore, when the crosshead is driven, the movable plate moves, and the movable die attached to the movable plate is fastened to the fixed die of the fixed plate. At the time of locking before the cross head is driven and the toggle mechanism is fully extended, the tie bar is tightened by the elastic restoring force generated by the extension of the tie bar. The direct pressure type mold clamping machine has a structure in which a mold is directly clamped by a fluid cylinder, for example, a hydraulic cylinder.

[0003] When the mold clamping is completed, the nozzle of the injection machine is advanced towards the die, and is injecting molten resin into the mold, if the detection means of the mold clamping completion,
In the case of the toggle-type mold clamping machine, the state in which the toggle mechanism is fully extended or the locking position before the toggle mechanism is fully extended is regarded as the completion of the mold clamping process, and each link of the toggle mechanism,
The position of the piston, movable plate, etc. of the mold clamping cylinder is detected by position detection means such as limit switches, encoders, potentiometers, etc., and when the detected value matches the value adjusted as the mold clamping completion position in advance, mold clamping is completed. Therefore, the process proceeds to the next step, ie, advancement of the nozzle, injection of the molten resin, and the like.

[0004]

In the case of a direct pressure type mold clamping machine, there is no particular problem since the mold is directly clamped by hydraulic pressure. However, in the case of a toggle-type mold clamping machine, the thickness differs depending on the mold, and the clamping force varies, so the mold thickness adjustment and the adjustment of the clamping force must be performed each time the mold is replaced. Problems may occur. That is, if the adjustment is made to be larger than the actual mold thickness, or if the adjustment is completed with the adjustment amount being insufficient, the required mold clamping force will not be obtained. Even if the erroneous adjustment is performed as described above, a state where the link mechanism is completely extended occurs. That is, the above-described position detecting means such as the potentiometer detects the completion of the mold clamping, and a transition signal to the next stroke, for example, the forward movement of the nozzle and the injection stroke is issued. Then, since the mold is not fastened with a predetermined mold clamping force, injecting the molten resin in such a state may cause a failure of a molded product or cause burrs or overpacking, and it is troublesome to remove these. It will take. As described above, tightening the mold at a predetermined pressure is important in determining the performance of the molded product, and an excessive mold clamping force is applied due to an operator's adjustment error, an abnormality of the automatic mold clamping device, or the like. If the clamping force is too small, the injection device may be damaged or the molded product may be defective.If the clamping force is abnormal, it is desirable to stop the process of transition to clamping. However, conventional mold clamping machines do not have any means for detecting abnormalities in the toggle mold clamping force.
The operation is performed assuming that the mold is clamped with the set clamping force. The present invention has been proposed in view of the above-described conventional situation. Specifically, when the mold is tightened with a predetermined mold clamping force, the process can proceed to the next step. It is an object of the present invention to provide a method for detecting an abnormality of a toggle-type mold clamping force and a device for detecting the abnormality, which does not shift to a subsequent step when the pressure does not reach the following step.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the invention of a method comprises the steps of: when driving a toggle mechanism (10) of a mold clamping machine with a hydraulic cylinder; The pressure in the cylinder (21) is compared with a set pressure, and when the comparison value is out of an allowable range, the subsequent stroke is stopped. A pressure sensor (53) for measuring a pressure in a hydraulic cylinder (21) for driving a toggle mechanism (10) of a mold clamping machine, and a mold clamping force setting for setting a mold clamping force. Tableware (51)
And a comparator (54) for comparing a measured value measured by the pressure sensor (53) with a set value set by the mold clamping force setter (51). And the controller (55) for stopping the subsequent stroke when the value is out of the allowable range.

[0006]

The invention according to claim 2 operates as follows.
That is, the pressure oil is supplied to the hydraulic cylinder 21 to drive the toggle mechanism (10) to clamp the mold. At this time , the pressure in the hydraulic cylinder 21 is measured by the pressure sensor 53,
Enter 4 At the same time, the mold clamping force is set by the mold clamping force setting device 51, and the set value is input to the comparator 54. Then, the value compared by the comparator 54 is stored in the controller 55.
And the controller 55 stops the subsequent process when the compared value is out of the allowable range.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In practicing the present invention, the values input to the comparator must be of equal dimensions. Therefore, it is necessary to use a converter to convert the set value set by the mold clamping force setter into pressure, or to convert the pressure value of the hydraulic cylinder into force. Alternatively, both the set value set by the mold clamping force setter and the pressure value of the hydraulic cylinder measured by the pressure sensor 53 may be converted into an electric signal and input to the comparator. However, the figure shows only an embodiment in which the set value set by the mold clamping force setter is converted into the pressure by the converter. Further, the present invention can be implemented such that, for example, a driver circuit provided separately is driven by a signal output from the comparator to stop the injection machine when the tightening force is abnormal. Alternatively, when an abnormality occurs, it can be displayed on a display, an audio device, or the like. However, an example is described in which a controller or the like provided in the injection molding machine is also used.

Referring to FIG. 1, it is easily understood that the mold clamping frame 1 according to the present embodiment is driven by the hydraulic cylinder unit 20 via the double toggle mechanism 10. The mold clamping frame 1 is composed of a fixed platen 2, an adjusting plate or a housing 3, and four tie bars 4, 4 ,. A movable platen 5 is slidably provided on the tie bars 4, 4,.... A fixed die 6 is mounted on the fixed platen 2, and a movable die 7 is mounted on the movable platen 5.

The double toggle mechanism 10 for driving the movable platen 5 includes one crosshead 11, a pair of crosslinks 12, and similarly a pair of short links 13, 13.
And a pair of long links 14, 14.
Ends of the cross links 12, 12 are rotatably connected to the cross head 11 by pins. Cross link 1
The other ends of the short links 13 and 13 are connected to the other ends of the short links 13 and 13 by pins.
The ends of a pair of long links 14, 14 are rotatably connected to the end portions by pins 17, 17, respectively. The other ends of the long links 14 and 14 are connected to the bracket of the movable platen 5 by pins 18 and 18, and the other ends of the short links 13 and 13 are rotated by pins similarly to the bracket of the housing 3. They are freely connected.

A hydraulic cylinder unit 20 for applying a thrust to the crosshead 11 comprises a hydraulic cylinder 21 provided in the housing 3 and a piston 22 provided in the hydraulic cylinder 21 so as to be able to reciprocate. Reference numeral 23 penetrates the housing 3, and its end is attached to the crosshead 11.

A hydraulic circuit 30 for supplying and discharging hydraulic oil to and from the hydraulic cylinder unit 20 includes a hydraulic pump 31 and a hydraulic pump 3.
It comprises a proportional pressure valve 33 branched from one discharge line 32, a proportional flow valve 36 with a pressure compensating valve interposed in the discharge line 32, and a direction switching valve 39. The port P of the direction switching valve 39 is connected to the cylinder head side of the hydraulic cylinder unit 20 by a supply line 40, and the port R is connected to the rod side of the hydraulic cylinder unit 20 by a discharge line 41.

The control device 50 includes a mold clamping force setting device 51, a converter 52 for converting a value set by the setting device 51 into a pressure value, and a pressure detecting a pressure on the cylinder head side of the hydraulic cylinder unit 20. Sensor 53 and pressure comparator 54
And an injection molding machine controller 55. The pressure comparator 54 compares the pressure detected by the pressure sensor 53 with the set pressure output from the converter 52, and compares the comparison value via a line 56 with the controller 5 of the injection molding machine.
5 is input. The injection molding machine controller 55 includes a calculation unit, a control unit, a memory, and the like. In addition to a program necessary for operating the injection molding machine, a program for processing a signal from the pressure comparator 54 when locking of the toggle mechanism 10 is completed. Is also input.

Next, the operation of the above embodiment will be described. pressure
When the locking of the crosshead 11 is completed,
Set the pressure value to be applied. Injection molding machine controller 51
, A pilot pressure is applied to the proportional pressure valve 33 through the line 34, so that the set pressure
The pressure oil discharge force e.g. 140 kgf / c ^{m 2} line 32
Is supplied to a proportional flow valve 36 with a pressure compensating valve. Then, a predetermined amount of pressure oil is supplied from the port P of the direction switching valve 39 to the cylinder head side of the hydraulic cylinder unit 20 through the supply line 40. Therefore, the piston 22 moves rightward in the figure and performs the mold clamping operation at a speed corresponding to the flow rate. That is, the crosshead 11 is connected to the tip of the piston rod 23, and the forward force of the piston rod 23 is transmitted from the crosshead 11 to the movable platen 5 by the double toggle mechanism 10, and the movable platen similarly moves rightward. I do. As a result, the movable mold 7 and the fixed mold 6 are locked.
Is, Russia Suheddo 11 becomes the locking completion. Then, the pressure rises in the discharge line 32, and the pilot pressure is applied to the unload valve 37 from the proportional flow valve 36 with the pressure compensating valve by the line 38, and the discharge oil is unloaded. The cylinder head 21 in the hydraulic cylinder unit 20 at this time
The pressure value A of, for example, 120 kgf / cm ² is detected by the pressure sensor 53 and applied to the pressure comparator 52.
At the same time, the value set to, for example, 150 tons by the mold clamping force setter 51 is converted to a pressure value B of 120 kgf / cm ² by the converter 52 and input to the pressure comparator 152. The pressure comparator 52 compares the values A and B and outputs the result to the controller 55. The injection molding machine controller 55 sets the setting value 12
When it is clamping at 0 kgf / cm @ 2, i.e. when it is in the allowable range of the set values 120 kgf / c m ² will continue driving, when the following or larger than the allowable range of the set value to stop the injection machine.

[0014]

As described above, according to the present invention, when the toggle mechanism of the mold clamping machine is driven by the hydraulic cylinder , the pressure and the setting in the hydraulic cylinder at the completion of the locking of the crosshead are set. When the comparison value is out of the allowable range, the subsequent stroke is stopped.Therefore, even if an excessive mold clamping force is applied due to some abnormality, or if the clamping force is too small, An effect unique to the present invention is obtained in that the injection device can be dealt with before it is damaged or a molded product is defective. In particular, according to the present invention, the hydraulic series
Measures the pressure inside the compressor and compares it with the set pressure.
Compared to the case where it is determined based on the flow rate supplied to the cylinder,
Sealing properties of O-rings and packings in hydraulic cylinders
Performance drops and hydraulic oil leaks from the head chamber to the rod chamber
Even if the amount increases, there will be no misinformation and always
There is an effect that correct information can be obtained.

[Brief description of the drawings]

FIG. 1 is a front view schematically showing a partial cross section of an example of a mold clamping machine used for carrying out the present invention.

[Explanation of symbols]

1 mold clamping frame 10
Double toggle mechanism 11 Cross head 20
Hydraulic cylinder unit 21 Hydraulic cylinder 51
Mold clamping force setting device 54 Pressure comparator 55
Injection machine controller

Continued on the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location B29C 45/76 8109-4F B29C 45/76 45/84 8109-4F 45/84

Claims (2)

(57) [Claims] 1. A type when the clamping device of the toggle mechanism (10) driven by a hydraulic cylinder, when the locking completion crosshead (11), and the pressure in the hydraulic cylinder (21),
A toggle-type clamping force abnormality detection method that compares with a set pressure and stops the subsequent stroke if the comparison value is outside the allowable range. 2. A pressure sensor (53) for measuring a pressure in a hydraulic cylinder (21) for driving a toggle mechanism (10) of a mold clamping machine, and a mold clamping force setting device (51) for setting a mold clamping force.
And a comparator (54) for comparing a measured value measured by the pressure sensor (53) with a set value set by the mold clamping force setter (51). A toggle type clamping force abnormality detecting device, comprising: a controller (55) for stopping a subsequent stroke when the set value is out of an allowable range.