JPH01157754A - Die closing power detecting method for toggle type die closing device - Google Patents

Abstract

PURPOSE:To prevent the breakdown of a device by setting the setting pressure of a die closing cylinder larger, measuring the time up to a die closing limit as well and deciding a die closing power based on the comparison of this time with preset time. CONSTITUTION:A fixed bar 17 is horizontally arranged at a link housing 3 side and striker 18 is provided on a crosshead 11 side by providing limit switches L1, L2. The switches L1, L2 are connected to a gate circuit 19 and a timer 20 and the circuit 19 are linked to a gate circuit 21. The setting pressure of a die closing cylinder 9 is set slightly larger than the necessary pressure taking into consideration an override characteristic, the detection signal of a pressure detector 23 is inputted to a pressure comparator 25 and a latch counter 22 is started. The over and under die closing powers are decided by comparing the output of the counter 22 with the set time to the die closing limit of a time setter 28. The breakdown of the device is prevented by the optimization of the die closing power.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold clamping force detection method for a toggle type mold clamping device. The present invention relates to a mold clamping force detection method for a toggle type mold clamping device.

FIG. 1 shows a schematic structure of a toggle type mold clamping device to which the present invention is applied.

In Fig. 1, the machine base 2 of the trouble mold clamping device 1
A link housing 3 and a fixed platen 4 are erected on both ends facing each other, and these are connected by four tie bars 5 on the top, bottom, left and right, and are firmly fixed with tie bar nuts 6. Reference numeral 7 denotes a movable platen whose four corners are slidably fitted and supported by tie bars 5, and the movable platen 7 and the link housing 3 are telescopically connected by two sets of trouble links 8, either vertically or horizontally. There is. A hydraulic cylinder 9 for mold clamping is horizontally fixed to the link housing 3, and the working end of its piston rod 10 is fixed to the center of a crosshead 11 that connects the upper and lower trouble links 8.

Reference numeral 12 denotes a guide shoe that guides the movable platen 7 by slidingly contacting the lower surface thereof. A fixed mold 13 and a movable mold 14 are mounted on the fixed platen 4 and the movable platen 7 so as to face each other.

In the trouble mold clamping device l configured as above,
When pressure oil is fed into the head chamber 15 of the hydraulic cylinder 9, the piston rod 10 moves forward and the crosshead 11.
A movable platen 7 connected by a link 8 is connected to a fixed platen 4.
Mold clamping is performed by moving to the side. Further, when pressure oil is fed into the rod chamber 16 of the hydraulic cylinder 9, the piston rod 10 is moved backward, the movable platen 7 is separated from the fixed platen 4, and the mold is opened.

Fig. 2 is a relationship diagram between the stroke of the clamping cylinder and the pressure inside the hydraulic cylinder during one molding cycle from the start of mold clamping to the completion of mold opening in a mold clamping device having a trouble mechanism, in which the horizontal axis shows the relationship between the stroke of the clamping cylinder and the internal pressure of the hydraulic cylinder. The stroke S of the tightening cylinder is shown, and the hydraulic cylinder internal pressure P is plotted on the vertical axis.
The solid line shows the mold closing curve, and the chain line shows the mold opening curve. Also,
Figure 2 shows a stroke-pressure diagram in a normal state with no abnormalities anywhere.As is clear from Figure 0, the so-called mold matching point o2 where both molds 13 and 14 come into contact from the mold clamping starting point 01. During the stroke X leading to , the pressure is maintained at approximately the same level while fluctuating between the pressure a and the pressure level. Further, after passing the mold matching point 02, the pressure P increases to the pressure C during the stroke x4, and after once decreasing, the pressure increases again and mold clamping ends at the point 03. At the time of mold opening, the pressure P suddenly drops from a starting point 03, and then the pressure rises slightly, and the mold opening is performed while maintaining almost the pressure d, and the mold opening is completed at the point 04 where the pressure increases.

By the way, the pressure C at the peak of the pressure diagram in FIG. 2 gives a mold clamping force F with a coefficient K depending on the thickness of the mold. That is, if the area of the cylinder is A, it is expressed by the following equation.

F=A*Ks c Therefore, if this pressure is controlled by a pressure control valve, the mold clamping force can be controlled.

However, if the set value of this pressure control valve (relief valve) is Pc corresponding to the pressure C.

Due to the override characteristic, as shown in Figure 3, the amount of oil escaping from the valve actually increases from a pressure of about 0.85 Pc, the amount of oil supplied to the mold clamping cylinder decreases, and the mold clamping time decreases. The process is extended and the system no longer operates according to the scheduled cycle.

Therefore, Pc of the pressure control valve is set to Pc = 1.1 to 1.2c in order to compensate for the above-mentioned override with respect to the pressure C required to generate mold clamping force according to the thickness of the mold.
By turning the nut on the link housing and shifting the timing when the molds are brought together, even if the circuit has the ability to build up pressure up to Pc, the actual pressure inside the cylinder can be adjusted so that it only builds up to C. This state is when the cycle is going as planned and the desired mold clamping force is being generated.

However, in reality, adjusting the timing at which the molds come together by turning the nut of the link housing by hand cannot be done accurately, and there is a risk that the mold clamping force will be exceeded.

If the mold clamping force is exceeded, there is a risk that a major accident may occur in which the platen, tie bars, tie bar nuts, etc. are damaged.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a mold clamping force detection method for a trouble mold clamping device that can reliably detect mold clamping over, shortage, and normality. There is.

FIG. 4 is a block circuit diagram illustrating one embodiment of the present invention, and the same parts in FIG. 1 as in FIG. 1 are given the same reference numerals.

In this embodiment, a fixed bar 17 is provided horizontally on the link housing 3 side, and a limit switch Ll,
L2 is isolated for a predetermined period, and the crosshead
A striker 18 is provided on the side.

Limit switch L1 detects the mold clamping start position, and limit switch L2 detects the mold clamping limit. Each of them is connected to a gate circuit 19 via an inverter I. A timer 20 measures the time from the start of mold clamping to the mold clamping limit.

The outputs of this timer 20 and gate circuit 19 are input to another gate circuit 21. The output of the gate circuit 21 is input to the latch counter 22.

On the other hand, the mold clamping cylinder 9 includes a pressure detector 23 , the output of which is input to a pressure comparator 25 via an amplifier 24 .

A pressure setting device 26 sets the set pressure Pc and inputs it to the pressure comparator 25.

Here, the inputs of both the pressure setter 26 and the amplifier 24 are compared, and the output from the pressure comparator 25 is fed to the latch counter 2.
2 is input.

The output of the latch counter 22 is input to a time comparator 27 and compared with the correct time from the start of mold clamping to the mold clamping limit set by a time setter 28. Based on this time difference, it is determined whether the mold clamping force is excessive or insufficient or normal.

In this case, if the time has elapsed, the signal is input to the alarm 29 or the machine operation stop circuit 30. It is also possible to notify the operator that the mold clamping force is excessive or to completely stop the device.

Next, the operation of this embodiment configured as above will be explained.

First, the mold clamping cylinder 9 is activated, and when the movable mold moves and is aligned with the fixed mold, the mold clamping operation is started.

At this time, the pressure detector 23 detects the pressure that starts to rise suddenly at the start of mold clamping, and the output signal is sent to the amplifier 24.
is amplified and input to the pressure comparator 25. Simultaneously with the generation of the pressure signal at the start of mold clamping, the latch counter 22 is started for time measurement. When a pressure signal at the mold clamping limit is generated, this signal is compared with the pressure set by the pressure setting device 26, and when the two match, the latch counter 22 also stops operating.

The coefficient result from the latch counter 22 is sent to the time comparison calculator 2.
7 and is compared with the reference time set by the time setter 28. Based on the compared times, it is determined whether the mold clamping force is excessive or insufficient or normal. If the measured time exceeds the reference time, the mold clamping force is over, so a signal is output to the alarm 29 or the operation stop circuit 30 to issue an alarm or stop the device.

In reality, when this over-clamping force condition occurs several times in a row, a warning is issued to the operator and the operation is stopped.

Of course, when the mold clamping force is normal or insufficient, it can be represented by a lamp or numerical value.

In this way, excess or deficiency of mold clamping force or normality is detected, making it easy to maintain normal operating conditions at all times.In the unlikely event that excessive mold clamping force is detected, an alarm will be issued to deal with this situation. It is possible to emit an alarm or stop the equipment.
No damage to tie bars or other accidents due to excessive mold clamping force will occur.

In the above embodiment, excess mold clamping force is detected based on the time until the mold clamping limit, and an alarm or a command to stop the device is issued. Depending on the difference and which one is larger, it is detected whether the mold clamping force is excessive, insufficient, or within a predetermined normal range, and this is fed back to the mold clamping force automatic adjustment device to adjust the mold clamping force. It is also possible to maintain the system in a normal state at all times.

As is clear from the above description, in the present invention, the time from the start of mold clamping to the mold clamping limit is compared with a reference time based on the pressure signal to determine whether the mold clamping force is excessive or insufficient, or is normal. Detection makes it easier to maintain normal driving. If overflow is detected, a warning can be issued or the apparatus can be stopped, so damage to tie bars, tie bar nuts, platens, etc. can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a front view (partial view) of the trouble mold clamping device to which the present invention is applied, Fig. 2 is a diagram showing the relationship between the stroke and pressure of the mold clamping cylinder, and Fig. 3 is a diagram of the relief valve. A diagram explaining the override characteristic, and FIG. 4 is a block circuit diagram showing one embodiment of the present invention. l...Trouble forming clamping device, 3...Link housing, 4...Fixed platen, 5
... Tie bar, 6... Tie bar nut,
7... Movable platen, 9... Mold clamping cylinder,
DESCRIPTION OF SYMBOLS 10... Piston rod, 19.21... Gate circuit, 20... Timer, 22... Latch counter, 23... Pressure detector, 25... Pressure comparator, 26... Pressure Setting device, 27... Time comparison calculator, 28... Time setting device, 29... Alarm device. 30...operation stop circuit. Patent applicant: Ube Industries, Ltd. Figure 4

Claims (1)

[Claims] A pressure control valve is provided to control the output of the mold clamping cylinder of the toggle type mold clamping device, and this set pressure is set slightly higher than the pressure required to generate the target mold clamping force, and the pressure signal at a predetermined position before the mold clamping limit is set. It is characterized by being configured to measure the time from the time to the mold clamping limit pressure signal, compare this time with a preset time, and determine whether the mold clamping force is excessive or insufficient or normal based on the comparison result. A method for detecting mold clamping force of a toggle type mold clamping device.