JPH0739019B2 - Stroke control device - Google Patents

Description

The present invention relates to a stroke control device for positioning a tack head forming tool in a riveting machine, for example.

[Conventional technology]

In a well-known riveting machine, as shown in FIG. 4, a rotary shaft 3 for power transmission between a motor 1 and a rivet head forming tool 2 is rotatably provided in a piston shaft 5 of a hydraulic cylinder 4. There is a device in which the lowering stroke of the piston shaft 5 (that is, the hydraulic cylinder stroke) is adjusted by the positioning device 6.

The positioning device 6 includes an operation rotary cylinder 6a held at the upper end of the hydraulic cylinder 4 so as to be rotatable in a fixed position, and an operation rotary cylinder 6a.
An annular nut plate 6b to which the piston shaft 5 is externally fitted and fixed to the upper end portion of the piston shaft 5 by being screwed into the inner diameter threaded portion of 6a, and inserted into the operation rotary cylinder 6a so as to be vertically movable. It consists of a stop block 6c and a piston 6d whose one end is fixed to the nut plate 6b and the other end is inserted into the long hole of the locking block 6c. The lowering stroke is positioned.

When the operating rotary cylinder 6a is rotated, this device causes the pin 6d to rotate.
Since the nut plate 6b that is stopped from rotating vertically moves, the descending stroke can be adjusted at the position of the nut plate 6b.

[Problems to be Solved by the Invention]

In the positioning device 6 as described above, the operation rotary cylinder is manually operated.
Since 6a is rotated, it is difficult to surely perform the positioning to the required descending stroke with one operation, and it takes time to perform the setup change and there is a problem in the positioning accuracy.

SUMMARY OF THE INVENTION An object of the present invention is to provide a stroke control device that can easily and accurately perform positioning by inputting numerical values and can obtain a large pressing force.

[Means for Solving the Problems]

In order to solve the above problems, a stroke control device according to the present invention is a hydraulic cylinder 40 in which a pressure rod 42 is provided on a piston 41, and a ball screw mechanism 30 for moving the piston 41 in the cylinder axis direction of the hydraulic cylinder 40. A servomotor 20 for driving the ball screw mechanism 30 and the hydraulic cylinder 40.
Hydraulic circuit to drive the piston 41
Output a drive signal p of the moving amount and the moving speed to the servomotor 20, while receiving an electric signal b corresponding to the load torque from the servomotor 20, and the load torque becomes 0 based on the electric signal b. Thus, the NC control unit 10 for outputting the control signal c to the pressure control valve 53 in the hydraulic circuit is used.

[Action]

The stroke control device of the present invention configured as described above,
The servomotor 20 rotates according to the information about the moving amount and moving speed of the piston 41 numerically input to the NC control unit 10 to move the piston 41 of the hydraulic cylinder 40 via the ball screw mechanism 30 and at the same time the hydraulic circuit. The hydraulic cylinder 40 is driven by. At this time, if a load torque is generated in the servo motor 20, the NC control unit 10 operates the pressure adjusting valve 52 to control the hydraulic pressure in the hydraulic cylinder 40 so that the load torque becomes 0 (zero). While always servo motor
The piston of the hydraulic cylinder 40 is moved by an amount corresponding to the rotation of 20.

When the piston 41 moves the required stroke set by the NC control unit 10, the servo motor 20 stops, and at the same time, the return signal from the NC control unit 10 closes the hydraulic circuit and opens the inside of the hydraulic cylinder 40. , While draining the oil, the piston is
41 returns to the initial state.

In this way, the piston 41 of the hydraulic cylinder 40 moves without affecting the rotational force of the servo motor 20 and following the rotation of the servo motor 20, so that the input moving amount and moving speed are high. Achieved with precision.

〔Example〕

 Hereinafter, embodiments will be described with reference to the drawings.

1 and 2 are schematic diagrams showing a stroke control device according to the present invention. As shown, the control mechanism is NC
A NC control unit 10 including a controller 11, a servo amplifier 12, and a converter 13. A driving signal p of a moving amount and a moving speed of a piston 41 of a hydraulic cylinder 40 described later, which is numerically input to the NC control unit 10, is a NC controller. It is output from 11 to the servo motor 20 via the servo amplifier 12. The servomotor 20 is fixed at a fixed position and is connected to a piston 41 having a pressure rod 42 of a hydraulic cylinder 40 via a ball screw mechanism 30, and the piston 41 is driven by the drive of the ball screw mechanism 30 by the servomotor 20. Hydraulic cylinder
Move inside 40 in the direction of the cylinder axis.

On the other hand, the hydraulic circuit as the drive source of the hydraulic cylinder 40 adjusts the hydraulic pressure in the hydraulic cylinder 40 by letting the discharge pressure of the hydraulic pump 51 escape to the tank 52 via the electromagnetic relief valve (pressure control valve) 53. The set pressure of the electromagnetic relief valve 53 is
It is controlled by the NC control unit 10 which receives an electric signal b corresponding to the load torque from the servo motor 20 and outputs a control signal c so that the load torque becomes 0 based on the electric signal b. As for the control signal c, the load torque of the servo motor 20 is transmitted to the servo amplifier 12 as an electric signal b, and the servo amplifier 12 outputs it via the converter 13 based on the signal b.

The stroke control device configured in this way is, for example,
As shown in FIG. 3, the pressure rod 42 can be connected to the rotary head a of the riveting machine and used as a drive mechanism thereof.

In this case, first, the moving amount and moving speed of the rotary head a are numerically input to the NC control unit 10. Next, when the device is started, the numerically input information is NC as an electric signal p.
The signal is output from the controller 11 to the servo motor 20 via the servo amplifier 12, the servo motor 20 starts to rotate based on the signal p, and tries to push the piston 41 downward via the ball screw mechanism 30.

At this time, the hydraulic pump unit 50 is also activated, and before starting the apparatus, the solenoid valve 54 is closed to return the oil into the tank 52 as shown in FIG. 2, but as shown in FIG. The solenoid valve 54 opens simultaneously with the rotation of the servo motor 20, and the hydraulic cylinder
The hydraulic pressure is supplied within 40. Therefore, as the piston 41 descends, oil is sent into the cylinder 40.

When the riveting jig attached to the pressure rod 42 reaches the head of the rivet, it cannot be sufficiently caulked with the hydraulic pressure used up to now, and the descending speed of the piston 41 is slow, that is, the piston by the ball screw mechanism 30 is slowed down. From the descending amount of 41,
The actual amount of lowering of the piston 41 is reduced, so that load torque is generated in the servo motor 20. Then, the NC control unit 10 outputs a control signal c to the electromagnetic relief valve 53 based on the electric signal b corresponding to the load torque from the servo motor 20 so that the load torque becomes zero.

The electromagnetic relief valve 53 raises the pressure in the hydraulic cylinder 40 while changing the set pressure based on the control signal c, and the piston 41 is pushed down. Therefore, the load torque becomes 00. Since the servo motor 20 continuously rotates to push down the piston 41, load torque is also continuously generated, and similar operation is continuously repeated to perform rebetting.

In this way, by performing feedback control so that the load torque is always 0, the piston 41 is driven by the highly accurate servo motor 20 in addition to the driving force of the piston 41 and the pressing force required for riveting. When the servomotor 20 is stopped, the riveting work is completed in the optimum state of the stroke determined by the servomotor 20.

After the servo motor 20 is stopped, a return command from the NC control unit 10 causes the solenoid valve 54 to close and the hydraulic circuit to close as shown in FIG.
The inside is opened to the tank 52. Further, when the servomotor 20 rotates in the reverse direction to pull up the piston 41, the oil in the hydraulic cylinder 40 is returned to the tank 52, and when the piston 41 is pulled up to the initial state, the solenoid valve 55 is closed and the hydraulic cylinder 40
Close the inside.

〔effect〕

As described above, the stroke control device according to the present invention is
The NC motor control unit 10 that can input numerical values drives the servomotor 20 with high output accuracy, and at the same time, by changing the set pressure of the pressure control valve 53 of the hydraulic circuit, the servomotor
The load torque of 20 is feedback-controlled, and the hydraulic cylinder 40 capable of obtaining a large output is made to follow the servomotor 20, so that the stroke control that requires a pressing force can be performed with high accuracy.

Also, when used as a driving means for a riveting machine, etc., when the tool is replaced or the work piece such as a rivet is replaced, if the input numerical value is changed, the optimum stroke and pressing force for a new tool or a new work piece can be obtained. Since it can be easily changed to, the setup can be easily changed.

[Brief description of drawings]

1 and 2 are diagrams showing the operation of an NC control unit and a hydraulic circuit in an embodiment according to the present invention, and FIG. 3 is a partial side view showing an attachment state when the embodiment is attached to a riveting machine. 4 and 5 are sectional views showing a conventional example. 10 …… NC control unit, 11 …… NC controller, 12 …… servo amplifier, 13 …… converter, 20 …… servo motor, 30 …… ball screw mechanism, 40 …… hydraulic cylinder, 41 …… piston, 42… … Pressurizing rod, 50 …… hydraulic pump unit, 51 …… hydraulic pump, 52 …… tank, 53 …… pressure control valve (electromagnetic relief valve), 54,55 …… solenoid valve, p …… servo motor drive signal , B ... electrical signal corresponding to load torque, c ... control signal.

Claims (1)

[Claims] 1. A hydraulic cylinder 40 fitted with a piston 41 having a pressure rod 42, and the piston 41
A ball screw mechanism 30 for moving in the axial direction of 40, a servo motor 20 for driving the ball screw mechanism 30, a hydraulic circuit for driving a piston 41 in the hydraulic cylinder 40, and the numerically input of the piston 41. The drive signal p of the moving amount and the moving speed is output to the servo motor 20, while the electric signal b corresponding to the load torque is received from the servo motor 20.
An NC control unit that outputs a control signal c to a pressure control valve 53 in the hydraulic circuit to control the amount of oil fed to the cylinder 41 so that the load torque becomes 0 based on the electric signal b. Stroke control device consisting of 10.