JP3145635B2 - Bending equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending apparatus for supplying a hydraulic fluid from a hydraulic pump driven by an electric motor to a hydraulic actuator to rotate a bending arm for bending.

[0002]

2. Description of the Related Art Conventionally, in a bending apparatus, when a large driving force is required, a hydraulic fluid from a hydraulic pump driven by a motor is supplied to a hydraulic actuator, and a large driving force is applied to the hydraulic actuator. We are trying to bend with strength. Further, since the rotation angle of the bending arm differs depending on the workpiece, the rotation angle of the bending arm is detected, and the bending arm is rotated by a predetermined angle by the hydraulic actuator. Further, an axial pressing force is applied to the workpiece by a hydraulic actuator during the bending, so as to prevent the thinning at the bending portion.

[0003]

However, in such a conventional device, it is necessary to synchronously control the rotation angle of the bending arm and the operation of the hydraulic actuator for applying the pressing force. Therefore, it is necessary to control the pressure liquid supplied to the hydraulic actuator for applying the pressing force, and there has been a problem that many control valves such as a precise flow control valve and a relief valve are required.

An object of the present invention is to provide a bending apparatus capable of controlling bending without using a precise flow control valve or a relief valve.

[0005]

The present invention employs the following means in order to solve such a problem. That is, a clamping die is movably supported on a bending arm rotatably supported around a bending die corresponding to a bending shape of a long workpiece, and the clamping die is moved toward the workpiece. And a bending device that clamps the workpiece by a bending die and a clamping die and supplies a hydraulic fluid to a hydraulic actuator that rotates the bending arm to perform a bending process. A bending hydraulic mechanism that connects both ports of a hydraulic pump rotatable in both directions and both ports of the hydraulic actuator via a conduit, and detects rotation of the bending arm. A sensor, and the electric motor based on a speed detected by the rotation detection sensor.
Control the number of rotations of the motor and
When the detected angle becomes a preset angle.
Operation of the hydraulic actuator by reversing the electric motor
A bending device is provided with a control circuit for controlling the direction .

Further, both ports of a hydraulic pump driven by an electric motor and capable of rotating in both directions according to the forward and reverse rotations, and both ports of a hydraulic actuator for pressurizing which applies an axial pressing force to the workpiece. And a pressurized hydraulic mechanism connected via a pipe line, a speed sensor for detecting the speed of the pressurized hydraulic actuator, and a speed detected by the rotation detection sensor and detected by the speed sensor. And a follow-up control unit that controls the number of revolutions of the electric motor of the pressurizing hydraulic mechanism based on the speed of the pressurizing hydraulic mechanism to cause the pressurizing hydraulic actuator to follow the bending arm.

[0007] Alternatively, both ports of a hydraulic pump driven by an electric motor and capable of rotating in both directions according to the forward and reverse rotations, and both ports of a hydraulic actuator for pressurizing which applies an axial pressure to the workpiece. And a pressurized hydraulic mechanism connected via a pipe line, and a pressure sensor for detecting the pressure of the pressurized liquid supplied from the pressurized hydraulic mechanism to the pressurized hydraulic actuator, and A pressurizing control means for controlling a maximum supply pressure to the pressurizing hydraulic actuator in accordance with a detection angle of the rotation detecting sensor by a maximum supply current to the electric motor of the pressurizing hydraulic mechanism may be provided.

Alternatively, both ports of a hydraulic pump driven by an electric motor and capable of rotating in both directions in accordance with forward and reverse rotation thereof, and both ports of a pressurizing hydraulic actuator for applying an axial pressing force to the workpiece. And a pressure sensor for detecting the speed of the pressurizing hydraulic actuator, and a pressure supplied from the pressurizing hydraulic mechanism to the pressurizing hydraulic actuator. A pressure sensor for detecting the pressure of the liquid, and controls the rotation speed of the electric motor of the pressurizing hydraulic mechanism based on the speed detected by the rotation detection sensor and the speed detected by the speed sensor. Follow-up control means for causing the pressurizing hydraulic actuator to follow the bending arm,
Pressurizing control means for controlling a maximum supply pressure to the pressurizing hydraulic actuator by a maximum supply current to the electric motor of the pressurizing hydraulic mechanism in accordance with an angle detected by the rotation detection sensor. .

[0009] The hydraulic actuator for pressurizing may include:
A pressure die that receives a bending reaction force during bending may be moved in the axial direction of the workpiece, or a rear end of the workpiece may be pressed in the axial direction.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 1, reference numeral 1 denotes a hydraulic pump which is rotatable in both directions. When the pump is rotated forward, hydraulic fluid is sucked from a first port 2 side and discharged to a second port 4 side. When the rotation is reversed, the hydraulic fluid is sucked in from the second port 4 side and discharged from the first port 2 side. The hydraulic pump 1 is connected so as to be driven to rotate by an electric motor 6 such as a servomotor.

The first port 2 and the second port 4 are connected to a first pipeline 8 and a second pipeline 10, respectively. The second pipeline 10 is a first to a second pipeline using three hydraulic cylinders. The three hydraulic actuators 12 to 14 are branched and connected to head-side ports 15 to 17, respectively.

The first conduit 8 is connected to rod-side ports 18 to 20 of the first to third hydraulic actuators 12 to 14 via first to third solenoid on-off valves 22 to 24, respectively. First to third hydraulic actuators 12 to 14
Are connected in parallel. First to third solenoid on-off valves 22 to
Reference numeral 24 denotes open positions 22a to 24a for connecting the first pipeline 8 to the rod-side ports 18 to 20 when an excitation signal is input.
In addition, when the excitation signal is not input, the configuration is switched to the closed positions 22b to 24b where the communication between the first conduit 8 and the rod-side ports 18 to 20 is interrupted by the spring biasing force.

The first pipeline 8 is connected to a hydraulic tank 30 via a first pilot check valve 32. The first pilot check valve 32 introduces the hydraulic pressure of the second pipeline 10 as pilot pressure, When the hydraulic pressure in the second pipeline 10 rises, the valve is opened to connect the first pipeline 8 to the hydraulic tank 30.

Further, the second pipe 10 is connected to the hydraulic tank 30 via a second pilot check valve 34,
The second pilot check valve 34 introduces the hydraulic pressure of the first pipeline 8 as pilot pressure, and opens when the hydraulic pressure of the first pipeline 8 rises, and the second pilot check valve 34 opens the second pipeline 10 and the hydraulic tank 30. Are connected to communicate with each other. The hydraulic pump 1, the electric motor 6, the pipelines 8, 10, the first to third solenoid on-off valves 22 to 2.
4. The bending hydraulic mechanism A is constituted by the relief valves 26 and 28, the hydraulic tank 30, and the pilot check valves 32 and 34.

As shown in FIG. 2, there is provided a bending die 42 formed in accordance with a bending radius of an elongated workpiece 40 such as a pipe. A corresponding groove 44 is formed. Bending die 42 is bending arm 4
The bending arm 46 is mounted to be rotatable by the first hydraulic actuator 12.

The rotation angle of the bending arm 46 is detected by a rotation detection sensor 36 using an encoder, as shown in FIG. In addition, a pressure sensor 39 that detects a hydraulic pressure supplied to the first hydraulic actuator 12 via the second conduit 10 is provided branched from the second conduit 10.

A clamping die 48 is movably supported on a bending arm 46 so as to face the bending die 42.
Is driven by the second hydraulic actuator 13 so that the workpiece 40 can be clamped between the bending mold 42 and the clamping mold 48. Further, a wiper mold 50 is disposed close to the bending mold 42, and a pressure mold 52 is movably supported on the slide table 53 so as to face the wiper mold 50. The pressure mold 52 is configured to be driven by the third hydraulic actuator 14 and applied to the workpiece 40 to receive a reaction force during bending.

The slide table 53 is slidably supported in the axial direction of the workpiece 40, and is configured to be driven by a pressurizing hydraulic actuator 54. The pressurizing hydraulic actuator 54 is configured such that a pressurized liquid is supplied from a pressurizing hydraulic mechanism B, as shown in FIG.
The pressurizing hydraulic mechanism B has the same configuration as the bending hydraulic mechanism A described above, and is supplied with hydraulic fluid from a hydraulic pump 66 driven by an electric motor 64.

A speed sensor 56 for detecting the operation speed of the pressurizing hydraulic actuator 54 is provided, and a pressure sensor 58 for detecting a hydraulic pressure supplied to the pressurizing hydraulic actuator 54 is also provided. Other hydraulic actuators 60 and 62 are also connected to the pressurizing hydraulic mechanism B.
In this embodiment, one hydraulic actuator 60 is disposed so as to drive a chuck mounted on a carriage (not shown), and the other hydraulic actuator 62 moves the chuck up and down. Are located.

The rotation detecting sensor 36, the pressure sensor 39, the bending hydraulic mechanism A, the speed sensor 56, the pressure sensor 58, and the pressurizing hydraulic mechanism B are connected to a control circuit 38. The control circuit 38 is well known. CPU 70, ROM 72, R
An input / output circuit 76 configured as a logical operation circuit centering on the AM 74 or the like and performing input / output with the outside is mutually connected via a common bus 78.

The CPU 70 inputs input signals from the rotation detection sensor 36, the pressure sensor 39, the speed sensor 56, and the pressure sensor 58 via the input / output circuit 76, and stores these signals and data in the ROM 72 and the RAM 74 and the data stored in advance. The CPU 70 outputs drive signals to the electric motors 6, 64, the first to third electromagnetic on-off valves 22 to 24, and the like via the input / output circuit 76 based on the control program thus performed.

Next, the control processing performed by the control circuit 38 will be described with reference to the flowcharts of FIGS. First, the workpiece 40 whose rear end is gripped by the chuck (not shown) is moved between the bending die 42 and the clamping die 48 by moving the carriage, and then the electric motor 6 is rotated forward to rotate the hydraulic pump 1. Drive. Therefore, the hydraulic pump 1 sucks the hydraulic fluid from the first port 2 side and discharges it from the second port 4 side. Further, an excitation signal is output from the control circuit 38 to the second electromagnetic on-off valve 23 to switch the second electromagnetic on-off valve 23 to the open position 23a (step 10).
0).

Therefore, the second solenoid on-off valve 23 and the first conduit 8 are connected from the rod-side port 19 of the second hydraulic actuator 13
The working fluid is sucked into the first port 2 of the hydraulic pump 1 via the. Then, pressure fluid is supplied from the second port 4 to the second hydraulic actuator 13 via the second conduit 10 and the head-side port 16.

At this time, there is a difference between the amount of the hydraulic fluid discharged from the rod side port 19 and the amount of the hydraulic fluid supplied from the head side port 16 by the volume of the cylinder rod. The first pilot check valve 32 is opened by the action of the pilot pressure from the second pipe 10 and the hydraulic fluid of the difference is supplemented from the hydraulic tank 30 via the first pipe 8.

In this way, the second hydraulic actuator 13 is driven, the clamping die 48 is moved toward the bending die 42, and the workpiece 40 is held between the bending die 42 and the clamping die 48. The first to third hydraulic actuators 12 to 1
When 4 is a double rod type hydraulic cylinder, the hydraulic tank 30 is not always necessary.

Next, an excitation signal is output to the third solenoid on-off valve 24 to switch to the open position 24a (step 11).
0). Thus, similarly to the above, the rod side port 20 of the third hydraulic actuator 14 and the third solenoid on-off valve 2
4. The liquid is sucked from the first port 2 of the hydraulic pump 1 via the first pipe 8, and is supplied to the head side port 17 via the second port 4 and the second pipe 10. Therefore, the third hydraulic actuator 14 is driven, the pressure mold 52 is moved toward the workpiece 40, and the pressure mold 52 is moved to the workpiece 40.
It is applied to.

Subsequently, a preset bending condition is read (step 120). The bending condition is bending arm 4
6, a rotation angle, an axial pressing force of the workpiece 40 corresponding to the rotation angle, and the like are input from a keyboard (not shown) or the like and are preset. For example, when bending at a right angle, the rotational pressure is 90 degrees, the axial pressure from 0 to 10 degrees is 2 ton, and the axial pressure from 10 to 80 degrees is 1 to.
n, the axial pressing force at a rotation angle of 80 to 90 degrees is 0.5 to
Enter n and set.

Next, an excitation signal is output to the first solenoid on-off valve 22 to switch to the open position 22a, and the first port 2 is switched via the rod-side port 18, the first solenoid on-off valve 22, and the first conduit 8. And the pressure fluid is supplied through the second port 4, the second conduit 10, and the head-side port 15 (step 130).

Thus, the first hydraulic actuator 12 is driven to rotate the bending die 42 together with the bending arm 46. The workpiece 40 is bent so as to be wound around the groove 44 of the bending die 42, and the rotation angle of the bending die 42 is detected by the rotation detection sensor 36. At this time, the bending arm 4 based on the pulse signal from the rotation detection sensor 36
The rotation speed of the first hydraulic actuator 12 is controlled by detecting the rotation speed of the electric motor 6 and controlling the rotation speed of the electric motor 6.

With the rotation of the bending arm 46, the pressurized hydraulic pressure is supplied from the pressurized hydraulic mechanism B to the pressurized hydraulic actuator 54 to slide the slide table 53, and the pressure mold 52 is moved to the work 40.
The workpiece 40 moves in the axial direction while being pressed against the workpiece 40.
Following control processing is performed so that the pressure mold 52 moves following the bending arm 46 (step 140).

In the follow-up control process, as shown in FIG. 5, first, the speed of the pressure mold 52 is read from the speed sensor 56 (step 141), and the bending arm is detected based on the pulse signal from the rotation detection sensor 36. Comparing the rotational speed of 46 with the speed of the pressure mold 52 from the speed sensor 56,
It is determined whether there is a tracking delay (step 142).

When the speed of the pressure mold 52 is low, the rotation speed of the electric motor 64 of the pressurizing hydraulic mechanism B is increased to increase the discharge amount of the pressurized liquid, and the operating speed of the pressurizing hydraulic actuator 54 is increased. To accelerate the pressure mold 52. Further, when it is determined that the speed of the pressure mold 52 is not the follow-up delay but the follow-up advance is faster (step 144), the rotational speed of the electric motor 64 of the pressurizing hydraulic mechanism B is reduced to reduce the pressure mold 52. Slow down. After executing the processes of steps 143 and 145, the process returns to the original process.

Next, the pressure of the pressurized liquid supplied from the pressurizing hydraulic mechanism B to the pressurizing hydraulic actuator 54 is controlled to control the axial pressing force applied to the workpiece 40 via the pressure mold 52. (Step 15)
0). In this pressurization control process, first, the rotation detection sensor 3
The rotation angle of the bending arm 46 from Step 6 is read (Step 151).

Then, it is determined whether or not the rotation angle has reached the change angle (step 152). Change angle is Step 1
In the case described above, it is initially determined whether or not the rotation angle has reached 10 degrees, based on the angle read by execution of the process 20. If it has not reached 10 degrees, the hydraulic mechanism for pressurizing B
The pressure detected by the pressure sensor 58 is read (step 154).

Next, the pressure detected by the pressure sensor 58 is changed to a predetermined pressing force (2 degrees up to a rotation angle of 10 degrees).
ton) is determined (step 15).
5) If the pressure is insufficient, a process of increasing the pressure is performed (step 156). The pressure increasing process is performed by the electric motor 6.
4 by increasing the current limit.

When the maximum supply current to the electric motor 64 is increased by increasing the limiting current, the driving torque of the hydraulic pump 66 is increased, and the maximum supply pressure from the hydraulic pump 66 may be increased. it can. Therefore, when the axial pressing force is insufficient, the driving force of the pressurizing hydraulic actuator 54 increases, and the pressing force increases.

If the pressurization is not insufficient, it is determined whether the pressurization is excessive (step 157).
When the pressurization is excessive, the current limit to the electric motor 64 is reduced, the maximum supply current is reduced, and the driving torque is reduced. As a result, the maximum supply pressure from the hydraulic pump 66 decreases.

When it is determined that the rotation angle has exceeded 10 degrees by repeatedly executing this control processing (step 15).
2) The set pressure is changed to a pressure corresponding to the axial pressure of 1 ton with a rotation angle of 10 to 80 degrees (step 15).
3). Then, the processing of step 154 and subsequent steps is executed,
The maximum supply pressure from the hydraulic pump 66 is increased or decreased by current limitation so as to reach the set pressure. Rotation angle is 80 degrees to 90
When the pressure is in the degree, the set pressure is 0.5ton
(Step 153), and the maximum supply pressure from the hydraulic pump 66 is increased or decreased by current limitation so as to reach the set pressure.

Next, it is determined whether or not the bending is completed based on whether or not the rotation angle detected by the rotation detection sensor 36 has become a preset angle, for example, 90 degrees (step 160). If the bending is not completed, the above-described processing of step 140 and subsequent steps is repeatedly executed.

When the bending is completed, the supply of the pressure liquid to the pressure hydraulic actuator 54 is stopped, and the application of the axial pressure to the workpiece 40 is stopped (step 170). Next, the output of the excitation signal to the first solenoid on-off valve 22 is stopped to switch to the closed position 22b, and the excitation signal is continuously output to the second and third solenoid on-off valves 23, 24 to open the open position 23a, 24a, the electric motor 6 is rotated in the reverse direction.

Therefore, the second and third hydraulic actuators 1
Hydraulic fluid is sucked into the hydraulic pump 1 from the second port 4 through the head-side ports 16 and 17 of the third and fourth ports and the second pipe 10, and the first port 2, the first pipe 8, the second and 3 Via the solenoid on-off valves 23 and 24 and the rod-side ports 19 and 20,
Pressure fluid is supplied to the third hydraulic actuators 13 and 14. As a result, the clamping die 48 and the pressure die 52 are moved and separated from the workpiece 40.

Subsequently, after the clamping mold 48 and the pressure mold 52 are retracted, the output of the excitation signal to the second and third solenoid on-off valves 23 and 24 is stopped to switch to the closed positions 23b and 24b.
An excitation signal is output to the first solenoid on-off valve 22, and the head-side port 15 of the first hydraulic actuator 12 and the second pipe 1
0, the hydraulic fluid is sucked through the second port 4, and the hydraulic fluid is supplied to the first hydraulic actuator 12 through the first port 2, the first conduit 8, the first solenoid valve 22, and the rod-side port 18. Supply.

Therefore, when the first hydraulic actuator 12 is driven to return the bending arm 46 to the original position and the rotation detecting sensor 36 detects that the bending arm 46 has returned to the original position,
The driving of the electric motor 6 is stopped, the output of the excitation signal to the first electromagnetic on-off valve 22 is stopped, and the driving of all the actuators 12 to 14 is stopped. Next, the electric motor 64 of the pressurizing hydraulic mechanism B is rotated in reverse to supply the pressurized liquid to the pressurizing hydraulic actuator 54, and the slide table 53 is retracted (step 180). After executing the processing of step 180, the present control processing is once ended.

In this embodiment, the slide table 53 is driven by the pressurizing hydraulic actuator 54 to apply an axial pressing force to the workpiece 40 via the pressure mold 52. The rear end of the workpiece 40 may be pushed by a pressurizing hydraulic actuator to apply an axial pressing force.

In addition to applying an axial pressing force via the pressure mold 52 by the pressurizing hydraulic actuator 54,
Furthermore, the rear end of the workpiece 40 may be configured to be pressed by a pressurized hydraulic actuator to apply an axial pressing force. In this case, two pressurizing hydraulic mechanisms B may be provided.

As described above, the bending apparatus of this embodiment is
The rotation detection sensor 36 is provided on the first hydraulic actuator 12 so that the operation of the first hydraulic actuator 12 can be controlled by the electric motor 6 without using a large and precise valve such as a hydraulic servo valve.
Can be controlled by the rotation of. When a plurality of first to third hydraulic actuators 12 to 14 are connected to the bending hydraulic mechanism A, the first to third solenoid on-off valves 22 to 24 are operated to switch the first to third hydraulic actuators. 3 hydraulic actuators 12 ~
Since circuit 14 is determined, a circuit can be configured by simple first to third solenoid on-off valves 22 to 24 without providing a large solenoid valve such as a switching valve for each of first to third hydraulic actuators 12 to 14. The hydraulic tank 30 may also have a small capacity, and the apparatus can be downsized.

With the hydraulic pressure mechanism B for pressurizing and the hydraulic pressure actuator 54 for driving the slide table 53, the bending arm 46 can be rotated with a simple structure without a complicated hydraulic circuit structure. The pressure mold 52 can be moved by following it. Further, by providing the pressure sensor 58, the maximum supply pressure to the pressurizing hydraulic actuator 54 can be controlled to control the axial pressing force.

As described above, the present invention is not limited to such an embodiment, and can be implemented in various modes without departing from the gist of the present invention.

[0049]

As described in detail above, the bending apparatus according to the present invention comprises a hydraulic actuator provided with a rotation detecting sensor,
The operation of the hydraulic actuator can be controlled by the rotation of the electric motor without using a large and precise valve such as a hydraulic servo valve. In the apparatus provided with the pressurizing hydraulic mechanism and the pressurizing hydraulic actuator, it is possible to move the bending arm by following the rotation of the bending arm with a simple configuration without using a complicated hydraulic circuit configuration. Further, by providing the pressure sensor, it is possible to control the maximum supply pressure to the pressurizing hydraulic actuator to control the axial pressing force.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a bending hydraulic mechanism used in a bending apparatus as one embodiment of the present invention.

FIG. 2 is a perspective view of a bending die, a clamping die, a pressure die, and the like of the bending apparatus of the present embodiment.

FIG. 3 is a block diagram illustrating a configuration of an electric system according to the present embodiment.

FIG. 4 is a flowchart illustrating an example of a bending control process performed by the control circuit according to the embodiment.

FIG. 5 is a flowchart illustrating an example of a follow-up control process performed by the control circuit according to the embodiment.

FIG. 6 is a flowchart illustrating an example of a pressurization control process performed by the control circuit according to the present embodiment.

[Explanation of symbols]

 A: Hydraulic mechanism for bending B: Hydraulic mechanism for pressurization 1, 66 ... Hydraulic pump 6, 64 ... Electric motor 12 ... First hydraulic actuator 13 ... Second hydraulic actuator 14 ... Third hydraulic actuator 36 ... Rotation detection sensor 38 ... Control circuit 39 ... Pressure sensor 40 ... Workpiece 42 ... Bending mold 46 ... Bending arm 48 ... Tightening mold 52 ... Pressure mold 53 ... Slide table 54 ... Pressure hydraulic actuator 56 ... Speed sensor 58 ... Pressure sensor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B21D 7/024

Claims (6)

(57) [Claims] A clamping die is movably supported on a bending arm rotatably supported around a bending die corresponding to a bending shape of a long workpiece, and the clamping die is attached to the workpiece. A bending apparatus that moves toward and clamps the workpiece by a bending die and a clamping die, and supplies a hydraulic fluid to a hydraulic actuator that rotates the bending arm to perform a bending process. A bending hydraulic mechanism is provided in which both ports of a hydraulic pump rotatable in both directions according to forward and reverse rotations and both ports of the hydraulic actuator are connected via a pipeline, and detects rotation of the bending arm. A rotation detection sensor for detecting the rotation speed of the rotation detection sensor.
Controlling the number of rotations of the electric motor and detecting the rotation.
When the angle detected by the sensor reaches a preset angle
The hydraulic motor
A bending circuit comprising a control circuit for controlling an operation direction of the bending machine. 2. A port for a hydraulic pump driven by an electric motor and rotatable in both directions in accordance with forward and reverse rotations of the hydraulic pump, and a hydraulic actuator for applying pressure to the workpiece in an axial direction. A hydraulic pressure mechanism for connecting both ports to each other via a pipeline, and a speed sensor for detecting the speed of the hydraulic pressure actuator, and a speed detected by the rotation detection sensor and the speed sensor And a follow-up control means for controlling the number of revolutions of the electric motor of the pressurizing hydraulic mechanism based on the detected speed and causing the pressurizing hydraulic actuator to follow the bending arm. Item 2. The bending device according to Item 1. 3. A port of a hydraulic pump driven by an electric motor and rotatable in both directions in accordance with forward and reverse rotations thereof, and a hydraulic actuator for applying pressure to the workpiece in an axial direction. A pressurized hydraulic mechanism connected to both ports via a conduit, and a pressure sensor for detecting the pressure of the pressurized liquid supplied from the pressurized hydraulic mechanism to the pressurized hydraulic actuator; and Pressurizing control means for controlling a maximum supply pressure to the pressurizing hydraulic actuator by a maximum supply current to the electric motor of the pressurizing hydraulic mechanism in accordance with an angle detected by the rotation detection sensor. Claim 1.
The bending apparatus described in the above. 4. A hydraulic pump driven by an electric motor and capable of rotating in both directions in accordance with forward and reverse rotations of the hydraulic pump, and a hydraulic actuator for applying pressure to the workpiece in an axial direction. A pressurized hydraulic mechanism having both ports connected via a pipeline is provided, and a speed sensor for detecting the speed of the pressurized hydraulic actuator and the pressurized hydraulic mechanism are supplied to the pressurized hydraulic actuator from the pressurized hydraulic mechanism. A pressure sensor for detecting the pressure of the pressure fluid, and the number of rotations of the electric motor of the pressurizing hydraulic mechanism based on the speed detected by the rotation detection sensor and the speed detected by the speed sensor. Follow-up control means for controlling the pressurizing hydraulic actuator to follow the bending arm; and the pressurizing hydraulic actuator according to an angle detected by the rotation detection sensor. Maximum supply pressure, characterized in that a pressure control means for the controlling the maximum current supplied to the electric motor of the pressurization fluid pressure mechanism according to claim 1, wherein the bending apparatus. 5. The bending process according to claim 2, wherein the pressurizing hydraulic actuator moves a pressure die that receives a bending reaction force during the bending process in an axial direction of the workpiece. apparatus. 6. The bending apparatus according to claim 2, wherein the hydraulic actuator for pressing presses a rear end of the workpiece in an axial direction.