JP3555095B2 - Pneumatic control device for press machine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
It belongs to the technology of a pneumatic control device that adjusts the pneumatic pressure of an actuator such as a die cushion device or a knockout device that is operated by compressed air provided in a press machine by using an electromagnetic valve.
[0002]
[Prior art]
The actuator is provided with a pressure sensor, a solenoid valve, and air pressure setting means, and according to the deviation between the air pressure set by the condition setting means and the actual air pressure obtained from the pressure sensor, the set air pressure is set to the actual air pressure. If it is higher, supply compressed air from the pneumatic source to the actuator with a solenoid valve and stop supplying it, or if the set air pressure is lower than the actual air pressure, release the compressed air from the actuator to the atmosphere. -There is a conventional technique of stopping the discharge and controlling the air pressure.
[0003]
[Problems to be solved by the invention]
In this prior art, the unit amount of the set air pressure is the same as the measurement unit amount of the actual air pressure.
When opening and closing the solenoid valve with the same unit amount as this unit amount, if a solenoid valve with a large effective area is used, the supply and discharge of compressed air by the solenoid valve will be repeated with high frequency, and the solenoid valve will be in a hunting state In addition, the solenoid valve having a small effective area has a disadvantage that it takes a long time for the actual air pressure to reach the set air pressure.
[0004]
Therefore, in this prior art, a solenoid valve having a large effective area is used in order to shorten the air pressure adjustment time, and the unit amount of the set air pressure and the measurement unit amount of the actual air pressure are made the same. Pneumatic control makes several times the same unit amount a dead zone to prevent a hunting state.
For this reason, this conventional technique has a problem that the variation in the actual air pressure becomes large due to the influence of the dead zone.
[0005]
[Means for Solving the Problems]
A solenoid valve that supplies and stops compressed air from an air pressure source to the actuator, or a solenoid valve that releases and stops the compressed air from the actuator into the atmosphere has a large effective area that can supply and release in a short time. Solenoid valve.
[0006]
When the difference between the set air pressure and the actual air pressure is within a predetermined range, the solenoid valve is operated for a previously stored pulse time to supply or discharge compressed air.
This pulse time is a time required for the actual air pressure to change by one unit amount or a plurality of unit amounts of the air pressure control at the reference differential pressure at that time, and the reference differential pressure at supply and discharge and the reference differential pressure at that time. It is assumed that a set of pulse times is stored in advance.
[0007]
The reference differential pressure referred to here is the difference between the air pressure of the pneumatic source and the actual air pressure of the actuator, and the release is the difference between the actual air pressure of the actuator and the atmospheric pressure.
When this reference differential pressure is changed for each unit amount of pneumatic control, the reference differential pressure and the pulse time at which the actual air pressure changes by one unit amount or a plurality of unit amounts of pneumatic control are set. It is stored in advance.
[0008]
When the solenoid valve is operated for one unit amount of the pneumatic control or a plurality of unit amounts of pulse time, the actual pneumatic pressure becomes a value changed by one unit amount or a plurality of unit amounts.
If necessary, a difference between the set air pressure and the actual air pressure is obtained, and a pulse time of one unit amount or a plurality of unit amounts is operated until the difference becomes zero.
As a result, the actual pneumatic pressure of the actuator can be made equal to the set pneumatic pressure, and the control amount can be set to one unit of the actual pneumatic pressure.
[0009]
If the difference between the set air pressure and the actual air pressure exceeds a predetermined range, determine the operating differential pressure when the actual reference pressure and the stored reference pressure match, and calculate the actual air pressure and this operating difference. When the sum of the pressures reaches the set air pressure, the operation of the solenoid valve is stopped and the pipeline is closed.
[0010]
This operating pressure difference is the difference between the actual air pressure at the time when the solenoid valve stops and the actual air pressure after the operation delay of the solenoid valve.
As a result, the actual pneumatic pressure of the actuator can be matched with the unit amount of the set pneumatic pressure, and the control amount can be matched with the unit amount of the actual pneumatic pressure.
[0011]
As a result, the disadvantages and problems of the related art can be solved.
[0012]
[Action]
The pulse time during which the solenoid valve operates to change the actual pneumatic pressure of the actuator by one or more units of pneumatic control, or the change in pneumatic pressure of the actuator when the operating solenoid valve is stopped A certain operating differential pressure is paired with a reference differential pressure and stored in advance, and using the stored reference differential pressure, pulse time and operating differential pressure, the solenoid valve is used by the pneumatic control device to operate the actuator. Since the pneumatic control is performed, the actual pneumatic pressure of the actuator can be made to match the set pneumatic pressure.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
The pneumatic circuit 4 of each actuator 3 includes a first solenoid valve 2A provided between the compressed air supply source 1 and the actuator 3, a second solenoid valve 2B provided between the actuator 3 and the atmosphere, The air pressure source 1 is provided with a first pressure sensor 12 for measuring the air pressure.
The pneumatic source 1 and the pneumatic circuit 4 of the individual actuators 3 which are not shown in FIG.
Further, in this embodiment, the first solenoid valve 2A and the second solenoid valve 2B, which are two-way solenoid valves, are constituted, but may be constituted by one four-way center-closed three-position solenoid valve.
[0014]
The block diagram of the pneumatic pressure control device 11 shown in FIG. 2 includes one first pressure sensor 12, a second pressure sensor 13 provided according to the number of actuators, and pneumatic pressure of the actuators and other control conditions. It comprises a condition setting means 14 to be set, an output signal 17 to the first solenoid valve 2A and the second solenoid valve 2B, a display means 16, and a control device 15.
The control device 15 includes an input / output arithmetic processing unit 15A, a first storage unit 15B for storing pulse time data, a second storage unit 15C for storing operating differential pressure data, and a setting input by the condition setting unit 14. And a third storage unit 15D for storing pressure data and the like.
[0015]
A pneumatic signal of the pneumatic source 1 is output from the first pressure sensor 12, an pneumatic signal of the actuator 3 is output from the second pressure sensor 13, and a set air pressure of the air pressure set for each actuator is output from the pressure setting means. Signals such as the control state and the air pressure of the actuator 3 are input to the control device 15, and the output signal 17 is an open / close signal for the first solenoid valve 2 </ b> A and the second solenoid valve 2 </ b> B. Have been.
[0016]
FIG. 3A shows an example of a state in which a drive signal is supplied to the first solenoid valve 2A for a pulse time T1 when the air pressure of the air pressure source 1 is PS.
The valve portion of the first solenoid valve 2A opens as shown in FIG. 3B, and the air pressure of the actuator 3 changes from P1 to P2 as shown in FIG. 3C.
[0017]
If the reference differential pressure ΔP1 is ΔP1 = PS−P1, and ΔP2 = P2−P1, the actual air pressure of the actuator 3 changes by ΔP2 when the solenoid valve is operated by a pulse signal for the time T1.
The reference differential pressure ΔP1 at which the ΔP2 is changed by one unit amount of the pneumatic pressure control and the pulse time T1 at that time are combined or changed for each of a plurality of unit amounts including one unit amount, and the reference difference at that time is changed. A set of the pressure ΔP1, the n unit amount to be changed, and the pulse time T1 at that time is stored in the first storage unit 15B in advance.
[0018]
Similarly, when the air pressure of the air pressure source 1 is PS, the state in which the continuous operation signal given to the first solenoid valve 2A is cut off is shown in FIG. 4A as an example.
The valve portion of the first solenoid valve 2A operates as shown in FIG. 4B, and the air pressure of the actuator 3 changes from P1 to P2 as shown in FIG. 4C.
[0019]
Assuming that the reference differential pressure ΔP1 is ΔP1 = PS−P1 and ΔP2 = P2−P1, this ΔP2 is an operating differential pressure. A pair of the operating differential pressure ΔP2 at that time is stored in advance in the second storage unit 15C.
The state on the first solenoid valve 2A side has been described with reference to FIGS. 3 and 4, but the same applies on the second solenoid valve 2B side except that ΔP1 = P1.
[0020]
The pneumatic control flow of each actuator 3 is shown in FIG.
The air pressure of the air pressure source 1 is set to PS, the set air pressure of the actuator 3 set by the condition setting means 14 and stored in the third storage unit 15D is set to PP, and the actual pressure of the actuator 3 measured by the second pressure sensor 13 at the present time. The pressure is P1, and the air pressure of the actuator 3 after the air pressure control is P2.
x is a boundary condition for controlling the solenoid valve by pulse time or by continuous operation, and is a positive value which is several times the control unit amount of the air pressure and is set in advance.
[0021]
Let (PP-P1) be the actual deviation ΔP3, and if this deviation ΔP3 is a positive value greater than zero, pressure increase control of the actuator is performed, so that the solenoid valve SV (2A) is opened and closed. When the deviation ΔP3 is a negative value smaller than zero, pressure reduction control of the actuator is performed, so that the solenoid valve SV (2B) is opened and closed, and is shown in FIGS. 5 (b) and 5 (d).
The solenoid valve SV (2A) and the solenoid valve SV (2B) have different purposes for controlling by increasing and decreasing the pressure of the actuator, but since the basic operation flow is the same, FIGS. This will be described in c).
If X, which is a boundary condition for controlling the solenoid valve SV (2A) by pulse time or by continuous operation, is smaller than the deviation ΔP3, the pulse time control shown in FIG. If it is larger, the continuous operation control shown in FIG.
[0022]
【The invention's effect】
When the difference between the set air pressure of the actuator and the actual air pressure is small, the solenoid valve is operated for pulse time, and when the difference is large, the actual air pressure is controlled by anticipating the operation delay of the solenoid valve. It is made to match the set air pressure.
[Brief description of the drawings]
FIG. 1 shows a pneumatic circuit of an actuator according to the present invention.
FIG. 2 shows a block diagram of a pneumatic control device of the present invention.
FIG. 3 shows a change when the solenoid valve of the present invention is opened for a pulse time.
FIG. 4 shows a change when the valve of the solenoid valve of the present invention is closed from an open state.
FIG. 5 shows a control flow of the pneumatic control device of the present invention.
[Explanation of symbols]
1 is a pneumatic source, 2A and 2B are solenoid valves, 3 is an actuator, 4 is a pneumatic circuit of each actuator, 12 is a first pressure sensor, 13 is a second pressure sensor provided for each actuator, and 14 is a condition. Setting means, consisting of an input processing unit 15A, a first storage unit 15B, a second storage unit 15C, and a third storage unit 15D, 15 is a control device, 16 is a display device, and 17 is opening and closing of a solenoid valve provided for each actuator. The signal, PS is the air pressure of the air pressure source, PP is the set air pressure of the actuator, P1 is the air pressure of the actuator immediately before control, P2 is the air pressure of the actuator after control, ΔP1 is the reference differential pressure, and ΔP2 is the operating differential pressure. , ΔP3 is PP-P1.

Claims (4)

The first electromagnetic valve between the pneumatic source and the actuator of the actuator such as a die cushion device or a knockout device provided on the press machine that operates with the compressed air, and the second electromagnetic valve between the actuator and the atmosphere. A pneumatic control device for adjusting the pneumatic pressure by opening and closing the first solenoid valve and the second solenoid valve;
A first pressure sensor for measuring the air pressure of the air pressure source, and each actuator is provided with a second pressure sensor for measuring the air pressure, and condition setting means for setting the air pressure and the like;
(A) The differential pressure between the pneumatic source and the actual pneumatic pressure of the actuator, and the reference differential pressure, which is the differential pressure between the actuator and the atmosphere, are changed for each unit of pneumatic control to obtain the first solenoid valve and the second solenoid valve. (2) Pulse operation of the solenoid valve to obtain a pulse time required for an operation differential pressure, which is a difference between actual air pressures of the actuator before and after the pulse operation, to change by a unit amount, and as a set of the reference differential pressure and the pulse time, It is stored in advance for each actuator.
(B) When the first solenoid valve is closed, the set air pressure of the actuator set by the condition setting means is higher than the actual air pressure of the actuator, and the difference between the set air pressure and the actual air pressure is determined in advance. If the difference is equal to or less than the preset reference pressure, a pulse time at the stored reference differential pressure that matches the actual reference differential pressure is obtained, and the first solenoid valve is operated during the pulse time.
(C) When the second solenoid valve is closed, the set air pressure of the actuator set by the condition setting means is lower than the actual air pressure of the actuator, and the difference between the set air pressure and the actual air pressure is determined in advance. If the difference is equal to or less than the preset reference pressure, the pulse time at the stored reference differential pressure that matches the actual reference differential pressure is obtained, and the second solenoid valve is operated during the pulse time.
With the above configuration, the pneumatic control device for a press machine performs pneumatic control of an actuator using a reference differential pressure and a pulse time stored in advance. In claim 1, when the operating differential pressure is equal to or less than a predetermined value, a reference differential pressure, an operating differential pressure, and a pulse time at that time are previously stored as a set for each of the operating differential pressures, and the actual reference differential pressure is stored. A pneumatic control device for a press machine, wherein a pulse time at the time of a stored reference differential pressure and an operating differential pressure corresponding to the pressure and the operating differential pressure is obtained, and the pneumatic control of the actuator is performed based on the pulse time. . The pneumatic pressure of an actuator, such as a die cushion device or a knockout device, provided on a press machine and operated by compressed air, a first electromagnetic valve between the pneumatic source and the actuator, and a second electromagnetic valve between the actuator and the atmosphere. In a pneumatic pressure control device for providing an electromagnetic valve and opening and closing the first electromagnetic valve and the second electromagnetic valve to adjust the air pressure,
A first pressure sensor for measuring the air pressure of the air pressure source, a second pressure sensor for measuring the air pressure of each actuator, and condition setting means for setting the air pressure and the like,
(B) The differential pressure between the pneumatic pressure of the pneumatic source and the actual pneumatic pressure of the actuator at that time, and the reference differential pressure, which is the differential pressure between the pneumatic pressure of the actuator and the atmosphere, are changed for each pneumatic control unit amount. And operating the first solenoid valve and the second solenoid valve in an open state to close them, and operating differential pressure which is a difference between the actual air pressure immediately before opening to closing and the stable actual air pressure after closing. The reference differential pressure and the operating differential pressure are stored as a set for each actuator in advance.
(B) When the difference between the set air pressure of the actuator set by the condition setting means and the actual air pressure of the actuator is equal to or more than a predetermined value, the first solenoid valve is increased when the pressure is increased, and the first solenoid valve is decreased when the pressure is reduced. 2 Operate the solenoid valve to open the pipeline.
(C) If the set air pressure of the actuator is higher than the actual air pressure of the actuator, the operating differential pressure at the time of the stored reference differential pressure corresponding to the actual reference differential pressure at that time is obtained. Then, when the added value reaches the set air pressure, the first solenoid valve is operated to close the line.
(D) If the set air pressure of the actuator is lower than the actual air pressure of the actuator, the operating differential pressure at the time of the stored reference differential pressure corresponding to the actual reference differential pressure at that time is obtained, and this operating differential pressure is obtained. Is added to the actual air pressure, and when the added value reaches the set air pressure, the second solenoid valve is operated to close the pipeline.
With the above configuration, the pneumatic control device for a press machine performs pneumatic control of an actuator using a reference differential pressure and an operating differential pressure stored in advance. A pneumatic control device for a press machine, characterized by having both of claim 1 or claim 2 and claim 3.

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