JPS6261740A - Press feeding device - Google Patents

Abstract

PURPOSE:To eliminate the pulsatory motion of driving torque of a press feeding device so as to make the life of the device longer, by adding position correcting torque on the basis of time-function reference torque when an actuator for actuating a feed bar is driven with position error correction. CONSTITUTION:A work carrying feed bar 6 is respectively driven in three axial directions by servo actuators 26, 29, and 32. For example, the actuator 32 calculates a reference speed V(theta,t) by means of a converter 41 from the reference speed F'(theta), crank shaft 37 detecting 38 rotational angle theta, and angular frequency (f) of a computer. On the other hand, the servo motor 32 is driven under a corrected condition by adding a corrected reference speed DELTAV(thetat) obtained by a converter 43 from the difference between the reference position F(theta) of a positional reference memory 35 and an actual position detected by a detector 48. If the reference speed F(theta) and angular frequency (f) of the crank shaft 37 are differentiated by means of a differentiator 51 and most of time- function reference torque tau(theta,t) is added by means of a compensator 52 when the servo motor 32 is driven, the correcting torque becomes smaller and pulsatory motions of torque can be eliminated. Accordingly, the mechanical backlash of this device is not promoted and the life of the device can be made longer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a press feeding device for moving a workpiece in a transfer press line.

[Prior Art] First, an outline of a driving section of a feeding device of a transfer press in which feeding operation is performed by a servo motor will be explained with reference to FIG.

A beam 2 is movably provided on a rail 1 extending in the left-right direction. A rail 3 is provided on the upper surface of the beam 2 in the front-rear direction, and a slider 5 having a vertical guide post 4 projecting thereon is superimposed on the rail 3. Then, a feed bar 6 equipped with a work transfer device (not shown) is slidably fitted to the guide post 4, so that the feed bar 0 can move in three axial directions.

A lift clamp housing device 8 having a required number of pairs of trolleys 7 is provided at a required location on the feed bar 6. The feed bar 7 is provided with a ram 9 that can move in and out in the vertical direction, and the feed bar 6 is clamped between the rollers 11 on the upper and lower rollers 101 side provided on the ram 9, and the ram 9 moves the feed bar 6 in the vertical direction and in the left and right directions. It is like restraining the person. In addition, a pinion 13 rotatably attached to the trolley 7 body is engaged with a pinion 12 provided downward from the ram 9, and a bevel gear 14
The shaft 15 is spline-coupled to the pinion 13 by fitting. Each of the trolleys 7 has a rack 1 extending in the front and back direction.
6.17 are provided so as to face each other. A bevel gear 18 that meshes with the bevel gear 14, and one shaft that meshes with the rack 16 and 17 are rotatably supported by a vertical shaft 20.
A binion 22.23, which is pivoted on the upper end of the vertical shaft 20.21 and pivoted on the lower end of the vertical shaft 20.21, is engaged with a rack 24.25 disposed parallel to the left-right direction. Each rack 24.25
are connected by connecting rods 26, 27 so that each lift clamp housing device 8 operates synchronously.

A lifting servo motor 28 and a clamping servo motor 29 are connected to the vertical shaft 20.21 of the lift clamp housing device 8 on the end side, and are fed to a shaft 30 provided on the beam 2 via a pinion 31. servo motor 32 is connected.

Next, each servo motor 28, 29, 32 and feed bar 6
Explain the movement of.

First, when the feeding servo motor 32 is driven, the beam 2 moves in the left-right direction, that is, moves forward and returns cJ, and the feed bar 6 mounted on the beam 2 similarly moves forward and returns. Also, when the lifting servo motor 28 is driven, the vertical axis 20
is rotated directly or via the rack 24, and the rotation is transmitted to the pinion 13 via the bevel gear 18°14 and the shaft 15, the ram 9 moves up and down, and the feed bar 6 similarly moves up and down. do. Furthermore, a servo motor 29 for clamping
When driven, the vertical shaft 21- rotates directly or via the rack 25, and the rotation of the pinion 19 is converted into lateral movement by the rack 16°17, and the trolley 7 moves in the front and back direction, and the feed bar 6 performs a clamping action.

Therefore, by appropriately controlling each servo motor 28, 29, 32, it is possible to cause the feed bar 6 to perform a desired operation.

Next, a control device for causing the feed bar 6 to perform desired operations will be explained with reference to FIGS. 4 and 5.

In order to simplify the explanation, the parts involved in controlling the feed servo motor 32 will be described below.

Base i! The generation computer 33 outputs signals to the speed reference memory 34 and the position reference memory 35, and detects the rotation angle of an encoder or the like that detects the rotation angle of the crankshaft 37 that rotates once per stroke of the press 36. A device 38 is provided so that the angle signal of the rotation angle detector 38 can be applied to the speed M sub-memory 34 and the position reference memory 35 via the crankshaft angle converter 39, and the angle signal from the speed W sub-memory 34 can be applied to the speed M sub-memory 34 and the position reference memory 35. The signal is transferred to the D/A converter 40
The signal from the crankshaft angle converter 39 can also be sent to the variable power F/V converter 41 via the variable power F/V converter 41.
/V converter 41, the signal from the position reference memory 35 can be sent to the adder 44 via the adder 42 and the D/A converter 43, and the variable power supply type F/V The signal from the converter 41 can also be applied to the adder 44.

The signal from the adder 44 is added to an i-adder 45, a control amplifier 46,
Feed servo motor 3 via thyristor power supply 47
For example, the feed amount of the beam 2 (see FIG. 3) sent by the feed servo motor 32 is detected by the position detector 48, and the A position signal can be sent to a position transducer 49, and a signal from the position transducer 49 can be applied to the adder 42 and via a velocity converter 350 to the adder 45. Note that the control devices for the lifting servo motor 28 and the clamp servo motor 29 have the same configuration as the control device for the above-described feed servo motor 32.

Base tI! The generation computer 33 includes a feed servo motor 3 that moves the beam 2 at a predetermined crankshaft rotation angle (press rotation angle) θ, as shown in FIG.
The relationship between the reference position (reference rotation angle) F(θ) of No. 2 is input as an arbitrary function, and the reference position of the rank shaft rotation angle (press rotation angle) θ and the feed servo motor 32 is determined as shown in FIG. The relationship between the speed F' (θ) is input as an arbitrary function, and during operation, the position reference memory 35 stores the reference position F (θ) corresponding to the crankshaft rotation angle θ, and the speed reference memory 34 stores the reference position F (θ) corresponding to the crankshaft rotation angle θ. The speed F' (θ) of the feed robot motor 32 corresponding to the shaft rotation angle 0 is stored.

When the crankshaft 37 rotates, the rotation angle detector 38 detects the crankshaft rotation angle θ, and a signal of the angle θ is sent to the crankshaft angle converter 39, where the crankshaft rotation angle θ is detected. A signal of θ and a signal of the crankshaft (press) angular frequency f are obtained, and the signal of the crankshaft rotation angle θ is sent to the speed reference memory 34 and the position reference memory 35, and the crankshaft angular velocity frequency f
The signal is sent to a variable power supply type F/V converter 41.

From the speed reference memory 34, the speed F' (
θ) is taken out and given to the D/A converter 40,
The digital signal is converted into an analog signal by the D/A converter 40 and applied to the variable power supply type F/V converter 41.
The speed F'(θ) of No. 2 is multiplied by the crankshaft angular velocity frequency f to obtain the reference speed V(θ, t)=F'(θ)·f, and the reference speed V(θ, 1) is It is output to the adder 44. Also, the speed F' (θ) is of the order 1i! Since the value is obtained by differentiating F(θ) with respect to θ, the variable power supply type F/V
The converter 41 converts it into a reference speed V(θ, 1) that changes with time as shown in equation (1) below.

The reference speed V (θ, 1> is applied to the thyristor power supply device 47 via the adders 44, 45 and the control amplifier 46, and the beam 2 is sent by the feeding servo motor 32 in response to a command signal from the thyristor power supply device 47. , or returned;
The stroke me is detected by a position detector 48,
The signal of the stroke] is sent to the speed converter 50 via the position detection fi 48 and the position converter 49, and is converted by the speed converter 50 into an analog speed signal for the feed servo motor 32, and the analog speed signal is The signal is returned to the adder 45 as a negative signal, and the feed servo motor 32 is controlled at a speed equal to the reference speed (θ, 1>).

On the other hand, the position F(θ) signal from the position detector 48 is converted into a position signal for the feed servo motor 32 by a position converter 49, and fed back to the adder 42, which corresponds to a signal of the crankshaft rotation angle θ. The reference position F(θ
) is taken out from the position reference memory 35 and added to the adder 42, the error between the signal from the position reference memory 35 and the signal from the position converter 49 is determined, and the signal corresponding to the error is added to the adder 42. 42 to the adder 44 via the D/A converter 43, a signal of the corrected reference velocity AV<θ, 1) for correcting the position error is sent to the adder 44, The signal of the reference speed V(θ, 1) and the modified reference speed JV(θ, 1).

t) are added, and the added signal is output to the adder 45. As a result, both the speed and position of the feed servo motor 48 are set to the reference speed ■(θ).

t) and the reference position IF(θ) from time to time.

In the case of the above-mentioned large transfer press, the weight of the load driven by the servo motor is large, so the moment of inertia of the motor shaft system becomes large, and the number of presses produced per minute (SP) increases.
m is gradually required to be larger, and for this reason, the position error during the movement of the feeder and at the stop end is reduced to the reference position F〈θ).
becomes larger compared to A large error during this movement poses a risk of interference with the mold of the press 36, and a large positional error at the stop end makes it difficult to place the conveyed material into the mold, reducing the forming precision of the pressed product. In other words, the quality deteriorates by 1a, so in order to eliminate this problem, conventionally, the control gain has been increased, and the control gain is determined by increasing the amplification factors of the D/A converter 43 and the control amplifier 46. A common method is to reduce the error with the feedback position.

[Problems to be solved by the invention] However, when the control gain is increased, the servo motor accumulates its energy in the elastic drive shaft system and transmits torque to the transfer press feeding device, which has a large moment of inertia, in order to correct position errors. Therefore, when the speed is corrected to a predetermined speed, the correction becomes excessive due to the release of stored energy, and deceleration control is forced again. As a result, the current of the servo motor does not become smooth as shown in Figure 8, and as shown in Figure 9. It pulsates like that.

As a result, the driving torque applied to the feed device of the transfer press naturally becomes a pulsating torque, which increases play in various parts of the feed device, causing failure and shortened service life. Since the Nuthyristor power supply device 47 is also frequently switched in both forward and reverse directions, it causes undesirable problems such as waveform distortion and other adverse effects on the factory power supply that supplies power to the motor.

In view of the above-mentioned circumstances, it is an object of the present invention to prevent pulsations in the current supplied to various servo motors and to prevent pulsations in the drive torque.

[Means for Solving the Problems] The present invention enables a feed bar, which is a workpiece conveyance device, to move in three axial directions, and provides three sets of servo actuators corresponding to the movement of each axis to move the feed bar. In a press feeding device that can move independently in three axial directions, the servo actuator reference speed changes over time by multiplying the servo actuator reference speed stored in advance corresponding to the press position by the press angular velocity frequency. a device for differentiating the servo actuator reference speed from the device for determining the reference speed to obtain a servo actuator compensation torque at a level necessary for the servo actuator, and a servo actuator reference position and a servo actuator stored in advance. A power supply device that controls the servo actuator based on the servo actuator reference speed outputted to determine the error with the position and correct the error in the position and the compensation torque from the device for determining the compensation torque. have.

[Function 1] In the present invention, the necessary compensation actuator torque is determined so that the press feed section is operated at a predetermined reference speed and position. ! iII! and control the actuator speed and position.

[Embodiment 1] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention, in which a feeding servo motor 32
Reference speed F' (θ) from the speed reference memory 34 of
and the signal of the crankshaft angular velocity frequency f from the crankshaft angle converter 39 can be applied to the active differentiator 51, and the output signal of the active differentiator 51 is sent to the control amplifier 46 and the sirisk via the torque compensator 52. The signal can be applied to an adder 53 provided between the power supply device 47 and the power supply device 47 . Note that the same reference numerals as those shown in FIG. 5 refer to the same parts.

The active differentiator 51 time-differentiates the product of the reference speed F' (θ) signal from the speed reference memory 34 and the crankshaft angular velocity frequency f signal from the crankshaft angle converter 39, as shown in the following (i). The equation gives (θ, 1) at the reference torque as a function of time.

...0) Reference torque τ(θ
, 1) is given to the torque compensator 52, which sets the signal level to a predetermined value, and then outputs the signal to the adder 53.
give to Also added to the adder 53 is an increase rl)1M (ie, torque in) of the speed error signal from the control amplifier 46.

For example, if the torque compensator 52 is set so that the reference torque from the torque compensator 52 is applied to the adder 53 with an accuracy of about 80% of the required torque, the remaining 20% of the speed signal is sent from the adder 45 to the control amplifier. 46 to the adder 53, the same control accuracy can be obtained even if the gain of the control amplifier 4G is lowered to 115 compared to the case of FIG. For this reason, servo control becomes much softer control,
The pulsating current superimposed on the motor current is reduced, and abnormal vibrations due to twisting, compression, tension, and rattling of the machine shaft system are reduced, and the feeding device can be operated more quietly, resulting in a longer machine life.

As described above, the motor torque required to operate at the reference speed and reference position is calculated and given to the thyristor power supply device 47, and the power supply device F47 gives a command to the servo motor, thereby controlling the servo motor. Since the speed can be controlled to a set speed, the conventional control method applies a corrected l-lux to the motor only after detecting the error between the reference speed, reference position, speed and position feedback values, as shown in Fig. 5. The control gain can be lowered and higher position and speed control accuracy can be obtained compared to the conventional method.

FIG. 2 shows another embodiment of the present invention. In the previous embodiment, a servo motor was controlled, but in this embodiment, a servo cylinder is controlled. In the figure, 54 is a servo cylinder, 55 is a servo valve, 56 is a hydraulic power source, 57 is a load driven by the servo cylinder 54, 58 is a power transmission mechanism for position detection, and 59 is a drain tank, as shown in FIG. Items with the same reference numeral indicate the same item. The control method shown in FIG. 1 can also be applied to such a servo cylinder 54.

Note that the present invention is not limited to the above-described embodiments, and can be applied to various actuators that can perform position control in addition to servo motors and servo cylinders. Other aspects of the present invention include that the detection may be performed from the movement of the slide portion, the mold, the servo motor, etc., that the circuit elements of 34 to 38, 40 to 47, and 50 to 53 can be converted into software by a computer. Of course, various changes may be made without departing from the spirit of the invention.

[Effects of the Invention] According to the press feeding device U of the present invention, there is no pulsation in the current supplied to the actuator, so there is no pulsation in the drive torque, and therefore, rattling of various parts of the mechanical system is less likely to occur, and failures can be avoided. It is possible to achieve various excellent effects such as not only the life is extended without causing any waveform distortion but also the factory power supply is not affected by waveform distortion or the like.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of one embodiment of the present invention, Fig. 2 is an explanatory diagram of another embodiment of the invention, Fig. 3 is a general explanatory diagram of a transfer press, and Fig. 4 is an explanatory diagram of a transfer press. An explanatory diagram of the press mold part of a transfer press, FIG. 5 is an explanatory diagram of a conventional example,
Figure 6 is a graph for explaining the relationship between the crankshaft rotation angle and the servo motor reference position, Figure 7 is a graph for explaining the relationship between the crankshaft rotation angle and the servo motor reference speed, and Figure 8 is a graph for explaining the relationship between the crankshaft rotation angle and the servo motor reference speed.
9 and 9 are graphs for explaining the relationship between the crankshaft rotation angle and the motor current (torque) at that time. In the figure, 2 is a beam, 28 is a servo motor for lifting, 29 is a servo motor for clamping, 32 is a feed motor, 3
3 is a reference generation computer, 34 is a speed reference memory, 35 is a position reference memory, 37 is a crankshaft, 38 is a rotation angle detector, 39 is a crankshaft angle converter, 41 is a variable power supply type F/V converter, 42, 44.45 is an adder,
46 is a control amplifier, 47 is a thyristor power supply device, 48 is a position detector, 49 is a position converter, 50 is a speed converter, 5
1 is an active differentiator, 52 is a torque compensator, 53 is an aperture device, 54 is a servo cylinder, 55 is a servo valve, 56 is a hydraulic power source, and 57 is a load.

Claims (1)

[Claims] 1) The feed bar, which is a workpiece conveyance device, can be moved in three axes, and three sets of servo actuators are provided to correspond to the movement of each axis, so that the feed bar can be moved independently in three axes. A device for determining a servo actuator reference speed that changes over time by multiplying a servo actuator reference speed stored in advance corresponding to a press position by a press angular velocity frequency, and a device for determining the reference speed A device for differentiating a servo actuator reference speed from the servo actuator to obtain a servo actuator compensation torque at a level required for the servo actuator, and for determining an error between a pre-stored servo actuator reference position and a servo actuator position and correcting the error in the position. 1. A press feeding device comprising: a power supply device that controls the servo actuator based on the servo actuator reference speed outputted for the purpose of the operation and the compensation torque from the device for determining the compensation torque.