JP2659538B2 - Press brake - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a press brake having a ram drive shaft for moving the ram up and down on both left and right sides of a vertically movable ram.

(Prior Art) In recent years, in press brakes, in order to perform positioning control of a relatively long ram with high accuracy, the ram is driven by two servo devices provided at both right and left ends of the ram. It has become.

In this kind, in a two-axis drive system in which a ram is driven by two servo devices, both servo devices are completely synchronized, and a mold attached to the ram is always parallel to a mold facing the ram. It is common to operate it.

(Problems to be Solved by the Invention) However, in the above-described conventional two-axis drive system in which the ram is always operated in parallel, the ram can only be moved in parallel at all times. There was a point.

For example, when trying to bend at one end of a long mold of a plate material having a relatively short bending width in a press brake,
Due to the deformation of the mold beam by the bending force, the inner part of the bent product becomes sweet.

Also, if there is an offset in the formed upper and lower mold beams, this directly affects the product accuracy.

Since both servo devices are always operated synchronously, a special-purpose asynchronous drive is not possible.

[Means for Solving the Problems] In view of the above-described conventional problems, the present invention provides a first and second ram drive shafts connected to both sides of a vertically movable ram,
First and second control elements for controlling the first and second ram drive shafts, and an NC for outputting a movement command to the first and second control elements
A device for detecting a moving position on both the left and right sides of the ram;
A second position detector, and a synchronous mode in which the first and second ram drive shafts can be controlled independently and an asynchronous mode in which the first and second ram drive shafts can be controlled synchronously. In a press brake configured to be switchable, an offset amount setting device capable of setting an inclination amount of the ram, a comparator for comparing detection values of the first and second position detectors, An offset value output unit for giving an offset value for a ram tilt to the first and second control elements based on a comparison value and a setting value of the offset amount setting device. A common movement command is output to the first and second control elements from a common movement amount calculation unit formed inside the NC device, and separate commands for separately driving both ram drive shafts under the asynchronous mode are provided. The movement amount calculation unit is formed inside the NC device and Movement amount calculating section is the first, is made to the second control element a configuration in which each connected individually.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

1 and 2 are side and front views of a bending machine (press brake) according to an embodiment of the present invention, FIG. 3 is an explanatory diagram of a hydraulic circuit, and FIGS. 4 and 5 are diagrams of the present invention. FIG. 3 is a block diagram of a control circuit showing one embodiment.

As shown in FIGS. 1 and 2, the bending machine (press brake) has a pair of left and right side frames 1, a lower table 3 is fixed to the lower front side of the frame 1, and a pair of left and right upper The cylinder 5 is provided. A lower mold 7 is attached above the lower table 3, and both ends of a ram 9 are attached to each of the cylinders 5 via joints that can swing with respect to the cylinder 5.
An upper mold 11 is attached below the ram 9 so as to face the lower mold 7. The axes driven by both cylinders 5 are ram drive axes D1 and D2.

A reinforcing plate 13 is mounted on the side frame 1, and the reinforcing plate 13 is provided with a position detector 15 for detecting the elevating operation of the ram 9.

An electric control panel 17 having an NC device is mounted on the left side frame in FIG. 2 of the side frame 1.

In the press brake having the above configuration, the lower mold 7 and the upper mold
When a bending command is given by a foot petal device (not shown) in a state where a plate material (not shown) is inserted between the ram 11, the ram 9 is lowered and a predetermined bending operation can be performed.

As shown in FIG. 3, the hydraulic circuit for driving the pair of cylinders 5 has a symmetric structure so as to correspond to both cylinders 5.

The servo valve SV for supplying hydraulic pressure to the cylinder 5 is a four-port, one-stage direct-acting type.

The pressure oil supplied to the servo valve SV is generated by a pump P driven by a motor M, and the hydraulic pressure generated by the pump P is supplied to the servo valve SV via a line filter ILF.
It is supplied to. The pressure oil generated by the pump P is controlled to a predetermined pressure by an electromagnetic proportional valve SOLE disposed between the servo valve SV and the line filter ILF.

The servo valve SV is connected to the cylinder 5 via oil passages OL1 and OL2. The oil passage OL1 is connected to the cylinder upper chamber, and the oil passage OL2 is connected to the cylinder lower chamber via various control valves.

Oil from the cylinder 5 is supplied to the oil passage OL2 by the servo valve S.
A counterbalance valve CBV that can provide a predetermined back pressure when returning to V is provided.

The oil passage OL2 is provided with a pilot check valve LV1 capable of returning the oil discharged from the cylinder 5 to the servo valve SV only when the pressure oil of the pilot portion is discharged based on the operation of the solenoid valve SOL1. Have been.

Further, in the oil passage OL2, in parallel with the counter balance valve CBV, the drain oil from the cylinder 5 is directly returned to the servo valve only when the pressure oil of the pilot portion is discharged based on the operation of the solenoid valve SOL2. Is provided with a pilot check valve LV2 capable of performing the following operations.

The hydraulic circuit further includes pressure detectors PS1, PS2, check valves PCV, LB3, and the like.

In the hydraulic circuit having the above configuration, when the ram 9 is raised, a predetermined flow rate of oil may be supplied to the lower chamber of the cylinder 5 via the oil passage OL2. If you want to lower the ram 9,
After operating the solenoid valves SOL1 and SOL2 to open the pilot check valves LV1 and LV2, the oil discharged from the lower chamber of the cylinder 5 may be returned to the servo valve SV from the oil passage OL2.

FIG. 4 is a system diagram of the servo device in the synchronous mode,
FIG. 5 is a system diagram of the servo device in the asynchronous mode.

As shown in FIG. 4, in the synchronous mode, the movement command Q output from the movement amount calculation unit 19 formed inside the NC device.
Is output to the control elements 25 and 27 via the error counters 21 and 23 of both the ram drive shafts D1 and D2. The feedback value F of the movement amount detected by the position detector 15 is fed back to the current value counters 29 and 31 of the ram drive shafts D1 and D2, respectively, and one of the feedback values is the error counter of both the ram drive shafts D1 and D2. 21,2
It is to be returned to 3.

On the other hand, between the two control elements 25 and 27, an offset amount setting device 33 and an error counter 37 as an offset value output means connected to a comparator 35 interposed between the amount position detectors 15 are provided. Is provided, and the count value of the error counter 37 is set to one of the control elements 25 and 27 for both control elements 25 and 27.
Are connected so as to be subtracted, and the other control elements 27 are added.

In the above system, assuming that both ram drive shafts D1 and D2 move in parallel and both position detectors 15 obtain the same feedback value, the output of the comparator 35 is zero.

Therefore, at this time, when a predetermined offset pulse is given to the offset amount setting unit 33, this is counted by the error counter 37, and one of the control elements 25 is minus (-).
And the other control element 27 is given a positive (+) offset, and both ram drive shafts D1.D2
, A predetermined offset is given.

Next, as shown in FIG. 5, in the asynchronous mode, movement amount calculation units 37 and 39 for driving both the ram drive shafts D1 and D2 are formed in the NC device. Are connected to the error counters 21 and 23, respectively. Further, the comparator 35 connected to the position detector 15 is disconnected, and the two ram drive shafts D1 and D2 are completely independent. However, this disconnection is actually performed by the error counter 37
At the output end.

Assume that in the state shown in FIGS. 4 and 5, the asynchronous mode shown in FIG. 5 is now shifted to the synchronous mode shown in FIG. At this time, since the control system is once disconnected, the ram drive shafts are moved, albeit in small amounts, and the parallelism may be lost.

However, in this example, this quantity is the same as that of the comparator 35 shown in FIG.
Is held by the error counter 37 which counts the outputs of the above, so that the parallelism is maintained immediately after the mode shift.

In the two-axis servo device having the above-described configuration, the synchronous mode and the asynchronous mode can be selectively used by mode switching. In the synchronous mode, perfect parallelism can be maintained and an appropriate amount of offset can be appropriately given. As a result, the ram 9 can be operated horizontally, inclined, or operated with a special specification, so that a high degree of bending can be performed.

In the above embodiment, the example of the hydraulic servo was shown, but the same applies to the electric servo.

It should be noted that the present invention is not limited to the above-described embodiment, but is to make appropriate design changes, and can be implemented in other aspects.

[Effects of the Invention] As can be understood from the above description of the embodiment, the present invention provides first and second ram drive shafts on both sides of a vertically movable ram 9 for vertically moving the ram 9. And a switch in which the first and second ram drive shafts can be independently controlled and switched to an asynchronous mode and the first and second ram drive shafts can be switched to a controllable synchronous mode in synchronization. It relates to a brake, and comprises an offset amount setting device 33 capable of setting an inclination amount of the ram 9 and a first and a second position detectors 15 and 15 for detecting a moving position on both right and left sides of the ram 9. A first and a second ram drive shaft for controlling the first and second ram drive shafts based on the comparison value of the comparator and the set value of the offset setting device 33; The control elements 25 and 27 are provided with an offset value output means for giving an offset value for the ram inclination. It becomes.

Then, in the synchronous mode, the first and second control elements 25 and 27 are transmitted from a common movement amount calculation unit 19 formed inside the NC device.
In the asynchronous mode, a separate movement amount calculation unit for separately driving the two ram drive shafts D1 and D2 is formed inside the NC device, and a separate movement amount calculation unit is provided. It is configured to be individually connected to the first and second control elements.

Therefore, in the present invention, the first and second drive shafts can be independently controlled to tilt the ram 9 to a desired angle, and after tilting the ram 9 to a desired angle, the tilt angle is maintained. The first and second ram drive shafts can be controlled synchronously to perform parallel movement. When switching from the asynchronous mode to the synchronous mode as described above, the control systems of the first and second ram drive shafts are temporarily disconnected, so that
Although the parallelism of the first and second ram drive shafts tends to collapse, the parallelism is corrected by the output of the offset value output means, and the ram 9 is immediately held at a desired angle. .

That is, according to the present invention, the first and second ram drive shafts on the left and right sides of the ram in the press brake are independently controlled to bend and lower the work, and the first and second ram drive shafts are set in the synchronous mode. When the fold down is continued, the problem of the temporary disconnection of the control system at the time of switching is not present, and the bending process by holding the ram horizontally or holding it appropriately inclined It can be done accurately.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 are side and front views of a bending machine embodying the present invention, FIG. 3 is an explanatory view of a hydraulic circuit, and FIG. 4 and FIG. FIG. 3 is a system diagram of the servo device in an asynchronous mode. 45 ... Comparator, 37 ... Offset value output means, D1, D2 ...
…axis

Claims (1)

(57) [Claims] 1. A first and a second ram drive shaft (D1, D2) connected to both sides of a vertically movable ram (9) and the first and second ram drive shafts (D1, D2). The first and second control elements to be controlled (25,
27), an NC device for outputting a movement command to the first and second control elements (25, 27), and first and second position detection for detecting the left and right movement positions of the ram (9). (15, 15), wherein the first and second ram drive shafts (D1, D2) can be independently controlled, and the asynchronous mode and the first and second ram drive shafts (D1, D2)
2) In a press brake configured to be able to switch to a synchronous mode in which control can be performed synchronously with the ram (9).
An offset amount setting device (33) capable of setting an inclination amount of the above, a comparator (35) for comparing the detection values of the first and second position detectors (15, 15), and the comparator (35) Based on the comparison value and the set value of the offset amount setting device (33).
Offset value output means for giving an offset value for the ram inclination to the control elements (25, 27) of
In the synchronous mode, a common movement command is output to the first and second control elements (25, 27) from the common movement amount calculation unit (19) formed inside the NC device. Separate displacement calculators for individually driving the drive shafts (D1, D2) are formed inside the NC device, and the separate displacement calculators are individually connected to the first and second control elements, respectively. A press brake, characterized in that the press brake has a configuration to be performed.