JPH0839152A - Work gripper of sheet bender - Google Patents

Abstract

PURPOSE:To prevent damage of a work by changing over closed loop control to open loop control by a changeover function means. CONSTITUTION:A main body frame 17 is moved against the energizing force of a spring 19 when a chain 27 is moved by driving a servo motor 31. The closed loop control is changed over to the open loop control when a position detecting sensor 37 arrives at a point 2. The hunting at the point 2 of a dog D is, therefore, lessened. A servo shaft 29 is stopped by the dog D and receipt of the signal by the position detecting sensor 37 when the main body frame 17 is further moved to the right side and the position detecting sensor 37 arrives at the point 1. Positioning of the origin is thus executed. As a result, the control of the servo shaft is stabilized and the much time is not needed for positioning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work gripper in a bending machine for holding a work and moving it in the front-rear direction for positioning when the work is bent by the bending machine.

[0002]

2. Description of the Related Art Conventionally, a work gripper 101, which grips a work W and moves it in the front-rear direction for positioning when a work W is bent by a bending machine, is shown in FIG. Further, the work clamp part 103 for gripping the work W is provided, and one end of a rod 105 extending in the front-rear direction is integrated with the rear part of the work clamp part 103. The rod 105 is provided with a body frame 107 that is movable in the front-rear direction. The main body frame 107 is a spring 1 mounted on the rod 103.
The work clamp portion 103 is brought into contact with the rear portion of the work clamp portion 103 by the biasing force of 09.

The body frame 107 is attached to a part of a chain 115 wound around a driving sprocket 111 and a driven sprocket 113. An encoder 119 is attached to the servo shaft 117 of the drive sprocket 111.
The servo motor 121 having the is connected.

With the above structure, when the servo motor 121 is driven to rotate the servo shaft 117 and the drive sprocket 111, the chain 115 is rotated downward in FIG. 103 also moves in the same direction, the work W abuts the reference pin 123, and the origin positioning is performed.

At this time, the rotation of the servo shaft 117 causes the main body frame 107 to move downward in FIG.
It is a mechanism that contracts 09 to generate a work traction force corresponding to the contraction amount.

[0006]

By the way, in the above-mentioned conventional work gripper 101, when performing the origin positioning, the reaction force of the contracted spring 109 increases as the body frame 107 moves downward in FIG. Since the servo motor 123 of the closed loop control for positioning performs output control in accordance with the reaction force that is continuously changing, shaft system vibration called hunting occurs in the deceleration region near the target position. Therefore, the servo axis 11 to be fed back
The control of 7 becomes unstable, it takes a long time for positioning, and the work may be damaged by vibration.

It is an object of the present invention to stabilize the control of the servo axis so that it does not take much time for positioning when performing the origin positioning, and the workpiece is not damaged by vibration in a bending machine. To provide a gripper.

[0008]

In order to achieve the above object, a work gripper in a bending machine according to a first aspect of the present invention grips a work when the bending machine performs bending work on the work. A work gripper that moves in the front-rear direction to perform positioning, and a work clamp part that clamps a work, a rod that is integrated in the rear part of the work clamp part and extends in the front-rear direction, and is penetrated by this rod. A body frame that is slidable in the front-rear direction and is in contact with the rear portion of the work clamp portion by the urging force of the ammunition, a servo motor that moves the body frame in the front-rear direction, and a movement amount of the body frame is detected. A position detector, a support member which is integrated with the rear portion of the main body frame and extends in the front-rear direction, the rear portion of the support member and the rod. And switching function unit for switching to an open loop control from the closed loop control provided in the rear and it is characterized in that it comprises an.

According to a second aspect of the present invention, there is provided a work gripper for a bending machine according to the first aspect, wherein as the switching function means, a position detection sensor or a plurality of dogs are provided at a rear portion of the indicating member and a plurality of dogs are provided at a rear portion of the rod. Is provided with a dog or a position detection sensor, respectively.

[0010]

By using the work gripper in the bending machine according to claim 1 as described above, the body frame is moved when the workpiece is clamped by the work clamp portion and the bending machine performs bending work on the workpiece. The origin positioning is performed by bringing the caulking work into contact with the reference pin, for example.

When performing this origin positioning, the servo motor is driven to move the main body frame by closed-loop control against the urging force of the ammunition while being guided by the rod, so that the support integrated with the main body frame is obtained. The member is also moved in the same direction. When this support member is moved,
The switching function means provided on the rear portion of the support member and the rear portion of the rod switches the closed-loop control to the open-loop control to move the main body frame and perform the origin positioning.

Therefore, the control of the servo axis is stabilized, the main body frame moves, and the origin positioning is performed, so that it does not take much time for the positioning. In addition, since the body frame does not vibrate when positioning the origin, the work is not damaged.

Further, in the work gripper of the bending machine according to the second aspect, a position detecting sensor or a large number of dogs are provided at the rear portion of the support member and a large number of dogs or a position detecting sensor are provided at the rear portion of the rod as switching function means. As a result, switching from closed loop control to open loop control is easily and reliably performed.

[0014]

Embodiments of the present invention will be described in detail below with reference to the drawings.

Referring to FIG. 1, a work gripper 1 in a bending machine is provided with a work clamp part 3 for clamping a work W. The work clamp part 3 includes a lower frame 5D, a vertical frame 5V and an upper frame. 5U
And the upper part of the lower frame 5D is the lower clamp jaw 7D, and the upper clamp jaw 7U is provided at the lower part of the upper frame 5D. A work detection sensor 9 that detects a work W is provided on the lower portion of the front surface of the vertical frame 5V.

With the above structure, when the work W is carried into the work clamp portion 3 from the left side in FIG. 1, it is detected by the work detection sensor 9. After the work W is detected, the work W is gripped by the cooperation of the upper clamp jaw 7U and the lower clamp jaw 7D.

At the rear part (right part in FIG. 1) of the vertical frame 5V in the work clamp part 3, front ends of rods 11 and 13 extending in the front-rear direction (left-right direction in FIG. 1) are integrated and formed. The rear ends of the rods 11 and 13 are attached to the bracket 15. A body frame 17 is fitted on the rods 11 and 13 so as to be movable in the front-rear direction. In order to constantly urge the body frame 17 forward and backward (left side in FIG. 1) on the rod 13,
A spring 19 as a bullet is interposed between the bracket 15 and the body frame 17.

An upper portion of the body frame 17 is slidably mounted on a guide rail 21 extending in the front-rear direction. Moreover, the upper end of the body frame 17 is attached to a part of the chain 27 wound around the drive sprocket 23 and the driven sprocket 25. A servo motor 31 is connected to the servo shaft 29 of the drive sprocket 23, and the servo motor 31 is provided with an encoder 33 as a position detector.

With the above structure, when the servo motor 31 is driven and the servo shaft 29 is rotated, the chain 27 is moved in the front-rear direction via the drive sprocket 23, so that the main body frame 17 is guided by the guide rails 21 to move back and forth. Will be moved in the direction. Therefore, the movement of the main body frame 17 causes the work clamp portion 3 holding the work hex W to be moved in the front-rear direction.

One end of a support member 35 extending in the front-rear direction is integrated with the rear portion of the body frame 17.
At the other end (right end in FIG. 1) of the support member 35, a position detection sensor 37, which is a switching function means for switching from closed loop control to open loop control, is provided. A plurality of dogs D, for example, five dogs D _{1 to} D ₅ are provided on the bracket 15.

Of the dog points D _{1 to} D ₅ , the dog point D ₃
And setting the point 3 to an intermediate position between the points 2, points 1 and dog point D ₄ and D ₅ in the dog point D ₄ at the intermediate position of D _5. The point 2 is a switching point from the closed loop control to the open loop control, and the point 3 is a position where the functions of the forced axis stop and the retry alarm are fulfilled.
Point 1 is the origin position.

With the above structure, the state in which the workpiece W clamped by the workpiece clamp portion 3 is in contact with, for example, the reference pin is the state shown in FIG. 2 (A).

In the state shown in FIG. 2A, when the servo motor 31 is driven to move the chain 27 to the right, the main body frame 17 is provided with a spring 19 as shown in FIG. 2B. Moved to the right against the power. When the position detection sensor 37 reaches the point 2, the closed loop control is switched to the open loop control. Therefore, there is little hunting at point 2 of dog D.

When the main body frame 17 is further moved to the right side and the position detection sensor 37 reaches the point 1 as shown in FIG. 2C, the signals from the dog D and the position detection sensor 37 are received and the servo axis is received. 29 is stopped and home positioning can be performed.

The closed loop control in which the body frame 17 is moved from FIG. 2 (A) to FIG. 2 (B) is shown in FIG.
As shown in (A), the positioning movement command passes through the position deviation counter 39, the D / A converter 41, and the amplifier 43.
Sent to the servo motor 31. The position is controlled by being fed back from the encoder 33 to the position deviation counter 33. The relationship between speed and time at this time is shown in FIG.
As shown in.

In the open loop control from FIG. 2B to FIG. 2C, as shown in FIG. 4A, the positioning movement command and the stop command are the position deviation counter 39, D /
It is sent from the amplifier 43 to the servo motor 31 via the A converter 41. The feedback signal from the encoder 33 is not taken into the position deviation counter 39. The relationship between speed and time at this time is as shown in FIG. 4 (B), and each signal is captured.

The load of the servo system when the servo motor 31 is used is increased by the reaction force of the spring 19 as shown in FIG. 5, and the speed of the servo axis during open loop control is The speed at which the specified torque can be generated is set in consideration of the load at point 1.

As described above, when positioning the work gripper 1 in the bending machine at the origin, the main body frame 17
Since the movement of is switched from the closed loop control to the open loop control, the servo axis control can be stabilized and the time required for positioning can be reduced. Further, since the main body frame 17 does not vibrate at the time of positioning the origin, the work W can be prevented from being damaged.

Since the position detecting sensor 37 and a large number of dogs D (D _{1 to} D ₅ ) are used as means for switching the closed loop control to the open loop control,
Switching from closed loop control to open loop control can be performed easily and reliably.

The present invention is not limited to the above-described embodiments, but can be implemented in other modes by making appropriate changes. Although the main frame 17 is moved from the servo shaft 29 by the drive transmission means including the drive sprocket 23, the driven sprocket 25 and the chain 27, it may be moved by a drive means such as a ball screw and a nut member or a rack and a pinion. Although the example in which the spring 19 is used as the ammunition has been described, the present invention is not limited to the coil spring and may be a damper or a leaf spring. The position detection sensor 37 may be a proximity switch, a limit switch, a photoelectric switch, or the like.

The position detecting sensor 37 is provided on the support member 35, and the dogs D are provided on the bracket 15.
The support member 35 may be provided with a large number of dogs D, and the bracket 15 may be provided with a position detection sensor 37.

[0032]

As will be understood from the above description of the embodiment, according to the invention of claim 1, when the work gripper is positioned at the origin position, the switching function means from the closed loop control to the open loop control is provided. The servo axis control can be stabilized by switching with
It is possible to prevent the positioning from taking a long time. Further, since the vibration is not generated when the main body frame is positioned at the origin position, it is possible to prevent the work from being damaged.

As a switching function means according to a second aspect, by providing a position detection sensor or a large number of dogs at the rear portion of the support member and a large number of dogs or position detection sensors at the rear portion of the rod, respectively, closed loop control to open loop control can be performed. Can be easily and reliably switched to.

[Brief description of drawings]

FIG. 1 is a front view showing an example of a work gripper in a bending machine according to the present invention.

FIG. 2 is an operation explanatory view when the work gripper is positioned at the origin position.

FIG. 3 is an explanatory diagram illustrating closed loop control.

FIG. 4 is an explanatory diagram illustrating open loop control.

FIG. 5 is an explanatory diagram illustrating a load of a servo system.

FIG. 6 is a plan view showing an example of a work gripper in a conventional bending machine.

[Explanation of symbols]

 1 Work gripper in bending machine 3 Work clamp part 11, 13 Rod 17 Main body frame 19 Spring (ammo) 29 Servo shaft 31 Servo motor 33 Encoder (position detector) 35 Support member 37 Position detection sensor D Dog W Work

Claims (2)

[Claims] 1. A work gripper for positioning a work by gripping the work and moving it in the front-rear direction when performing bending work on the work with a folding machine, and a work clamp part for clamping the work, and the work. A rod which is integrated with the rear portion of the clamp portion and extends in the front-rear direction, and a body frame which is penetrated by the rod and is slidable in the front-rear direction and abutted on the rear portion of the work clamp portion by the urging force of an ammunition machine. A servo motor for moving the main body frame in the front-rear direction, a position detector for detecting the amount of movement of the main body frame, a support member integrated in the rear part of the main body frame and extended in the front-rear direction, Switching function means for switching from closed-loop control to open-loop control provided on the rear portion of the support member and the rear portion of the rod. A work gripper for a bending machine. 2. The position detecting sensor or a large number of dogs is provided at the rear portion of the supporting member as the switching function means, and the large number of dogs or a position detecting sensor is provided at the rear portion of the rod, respectively. Work gripper in the described bending machine.