JPH0359798B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a speed control device for a press using a speed-variable electric motor as a drive source for reciprocating movement of a slide.

(Prior art) As a press machine that uses an electric motor as a drive source,
Since the rotational speed (i.e., rotational speed) of the electric motor rapidly decreases at the start of continuous operation, the rotational speed of the electric motor is adjusted so that the rotational speed reaches a predetermined value when a load is applied to the electric motor (i.e., at the start of continuous operation). The rotational speed of the electric motor is determined when no load is applied to the motor (in the present invention, this is referred to as "during no-load operation") and when a load is applied to the motor (in the present invention, this is referred to as "during continuous operation"). There is a press machine that is equipped with a circuit that switches between 1 and 2, and sets the rotation speed of the motor to a higher value than the value during continuous operation while monitoring the value of a speedometer that displays the rotation speed of the motor.

However, in such a press, the speed must be set while checking the value of the speedometer, which constantly fluctuates due to changes in the rotation speed of the electric motor, changes in the electric circuit, etc., so the speed setting work is troublesome. The set value varies depending on the operator, making speed setting difficult to operate. Further, in this press, the number of rotations during continuous operation must be determined from the value of the speedometer by calculation or a conversion table, which makes the speed setting work more troublesome. Furthermore, in this press, the rotational speed of the electric motor is switched after the clutch is engaged for continuous operation, so that the stroke at the first movement of the slide does not reach a predetermined value.

Another press machine of this type is equipped with a circuit that switches the value displayed on the speedometer between no-load operation and continuous operation, in addition to the switching circuit for the rotation speed. There is. However, with this press, the speed must be set while checking the value on the speedometer, which constantly fluctuates due to changes in the rotational speed of the motor, changes in the electrical circuit, etc., so the speed setting work is troublesome. The values vary depending on the operator, making speed setting difficult to operate. Further, in this press, the rotational speed of the electric motor is changed after the clutch is engaged for continuous operation, so that the stroke at the first movement of the slide does not reach a predetermined value.

(Object of the Invention) An object of the present invention is to provide a speed control device for a press machine that allows anyone to easily set the rotational speed of an electric motor to a correct value.

Another object of the present invention is to provide a control device for a press machine in which the stroke of the slide is set to a predetermined value from the beginning.

(Structure, operation, and effect of the invention) The speed control device for a press according to the present invention uses an electric motor whose rotational speed can be changed as a drive source for reciprocating the slide, and the speed control device of the present invention has a speed control device for a press machine in which the rotational speed of the electric motor is changed during continuous operation. A switching means for switching to a different value depending on the no-load operation, a speed setting means for setting the rotation speed of the electric motor, and a control means for controlling the rotation speed of the electric motor based on information from the switching means and the speed setting means. and display means for displaying the actual rotation speed of the electric motor. The speed setting means includes a variable resistor having a knob for setting the rotation speed of the electric motor, and a scale disposed near the knob to indicate the rotation speed of the electric motor during continuous operation in conjunction with the knob. It is equipped with a scale plate marked with.

The value indicated by the joint action of the knob of the speed setting means and the scale is the target rotation speed when the press is operated continuously, and does not change due to changes in the rotation speed of the electric motor, changes in the characteristics of the electric circuit, etc.
Therefore, according to the present invention, the operator sets the target rotation speed while looking at the value indicated by the knob and scale without checking the actual rotation speed displayed on a display means such as a speedometer. Because you can
Anyone can easily set the rotational speed of an electric motor to the correct value during continuous operation.

In another speed control device of the present invention, the switching means includes a first switch for switching the rotation speed of the electric motor to a value for continuous operation before continuously operating the press machine; and a second switch for continuously operating the press after being operated.

Therefore, according to the present invention, there is also provided a first switch that switches the rotational speed of the electric motor to a value for continuous operation before starting continuous operation, and a press machine that operates continuously after the first switch is operated. second to let
Since the switch is provided, the stroke of the slide is set to a predetermined value from the beginning.

(Example) Hereinafter, an example of the present invention shown in the drawings will be described.

The press 10 shown in FIG. 1 includes a bed 14 on which a bolster 12 is placed. The bed 14 is provided with a plurality of posts 16 extending upward and parallel from the bed, and a slide 18 is disposed on the posts so as to be movable up and down. A lower die 20 is attached to the bolster 12, and an upper die 2 is attached to the slide 18.
2 is attached. At the top of slide 18,
A pair of connecting rods 24 are provided that extend upward in parallel from the slide, and the lower end of a crank bin 28 supported on a crankshaft 26 is connected to the upper end of the connecting rod.

The crankshaft 26 is rotatably supported by the frame 30 around an axis extending in the horizontal direction.
A flywheel 32 is provided on the crankshaft 26, and a clutch 34 is disposed inside the flywheel 32. flywheel 32
is a pulley 38 provided on the rotating shaft of the motor 36.
are connected to each other by a belt 40.

The motor 36 is a three-phase electric motor whose speed can be changed, and in the illustrated example, it is an eddy current motor including a motor body 36a, a coupling 36b, and a tacho generator 36c, as shown in FIG.

In the above embodiment, the press machine converts the rotational motion of the motor 36 into reciprocating motion by a motion conversion mechanism equipped with the crankshaft 26, and moves the slide 26 in the vertical direction. It may be a press machine that converts motion into reciprocating motion by a motion conversion mechanism using a cam.

The press 10 also includes a speed control device 42 for controlling the number of revolutions or rotational speed of the motor 36, as shown in FIG. Speed control device 42
includes a control circuit 44 for controlling the rotation speed of the motor 36, a switching circuit 46 for switching the rotation speed of the motor 36 between continuous operation and no-load operation, and a variable circuit 46 for setting the rotation speed of the motor 36. resistor 48
and a speedometer 50 that displays the number of rotations of the motor 36.

The control circuit 44 includes a speed controller that amplifies the deviation between the speed setting voltage set between terminals O and P and the speed feedback voltage input from the tachometer generator 36c, and a thyristor module that controls the excitation current supplied to the coupling 36b. The thyristor module is mainly composed of a pulse generator, a pulse generator that generates a trigger pulse for igniting the thyristor of the thyristor module, and various protection circuits. Such a control circuit can be purchased with the electric current motor from the manufacturer of the motor.

In the illustrated example, the control circuit 44 has terminals A and B connected to the tachometer generator 36c and the speedometer 50, terminals C, K, and J connected to the coupling 36b, and terminals U and W connected to the coupling 36b.
is connected to two of the power lines for supplying power to the motor 36, terminal P is connected to one terminal of the switching circuit 46, terminal O is connected to the slider of the variable resistor 48, and terminal L is connected to two of the power lines for supplying power to the motor 36.
are connected to one end of the resistor of the variable resistor 48, respectively. According to such a control circuit 44,
The rotation speed of the motor 36 (this is the motor main body 36a
The rotation speed is not the rotation speed of the rotating shaft provided with the pulley 38. ) compares the voltage between terminals O and P with a feedback voltage proportional to the rotational speed generated by the tachometer generator 36c, and automatically adjusts the excitation current supplied to the coupling 36b according to the deviation value. is maintained at a predetermined value.

The switching circuit 46 includes a variable resistor 52 and first and second contacts 54a and 54b. The resistor of the variable resistor 52 is connected to the terminal P of the control circuit 44 and one end of the resistor of the variable resistor 48 for speed setting, and the slider is connected to the terminal P of the control circuit 44. First and second contacts 54a, 56a
are connected in series with each other and in parallel with the variable resistor 52.

The first contact 54a is a normally closed contact of the continuous operation preparation relay 54, which is energized for a certain period of time when the press 10 is ready for continuous operation. Therefore, a continuous operation preparation relay 5 is provided on the operation panel 58 to switch the rotation speed of the motor 36 to the value for continuous operation before the press machine is operated continuously.
A first switch 60 for automatic return, ie, a continuous operation preparation switch 60, is provided for energizing 4.

A normally open contact 60a of a continuous operation preparation switch 60 is provided in the energizing circuit for the continuous operation preparation relay 54, as shown in FIG. Therefore, the continuous operation preparation relay 54 is connected to the continuous operation preparation switch 6.
0 is turned on, the current is turned on, and the current is cut off after a certain period of time, for example, 10 seconds.

The second contact 56a is the normally closed contact of a continuous running relay 56, which is energized when the clutch 34 is engaged (motor loaded). For this reason, as shown in FIG. 3, the operation panel 58 is provided with a second switch for automatic return, that is, a continuous operation switch 62 for instructing the press machine 10 to operate continuously and for energizing the relay 56. There is.

In the current supply circuit to the relay 56, as shown in FIG. 2, a normally closed contact 62a of the continuous operation switch 62 and a normally closed contact 54b of the continuous operation preparation relay 54 are arranged in series. Therefore, the continuous operation relay 56 is energized by turning on the continuous operation switch 62 while the contact 54b is closed, and is self-held until the clutch 34 is released.

The variable resistor 48 is a rotary volume, and its low resistance is connected to the terminal L of the control circuit 44 and the switching circuit 46, and the slider is connected to the terminal O of the control circuit 44. As shown in FIG. 3, the slider is provided with a knob 64, and the knob 64 is provided with an indicator 66 that indicates the position of the slider.

As shown in FIG. 3, the operation panel 58 is provided with a scale plate 68 for indicating the motor rotation speed set by rotating a knob 64. As shown in FIG. The scale plate 68 has a scale 70 and numbers 72 that together with the indicator 66 of the knob 64 indicate the number of rotations of the motor 36 when a load is applied to the motor 36.
is written. The scale 70 and the numbers 72 are provided along the rotation locus of the knob 64, that is, along an imaginary circle extending around the knob 64.

The operation panel 58 further includes a speedometer 50 and a pushbutton switch 74 for turning on the power of the press machine 10.
is provided.

In operation, the press 10 is first powered on. This causes the motor 36 to start rotating. At this time, the normally closed contacts 54 and 56 of the motor 36 are closed, so that the variable resistor 52 is short-circuited by the first and second contacts 54a and 56a, and the variable resistor 48 is connected to the control circuit 44. Therefore, the rotation speed is determined by the variable resistor 48.

Next, when the knob 64 is rotated and the rotational speed of the motor 36 is set to the continuous operation value, for example, 500 revolutions per minute as shown in FIG.
is rotated at a higher rotation speed than the set rotation speed,
The actual rotational speed of the motor 36 is displayed on a speedometer 50 as shown in FIG. 3A. At this time, motor 3
The rotation speed of the motor 36 when a load is applied to the speedometer 6, that is, the target rotation speed, is jointly indicated by the indicator 66 and the scale 70.
The desired rotation speed can be set by looking at the indicator 66 and scale 68 without looking at the value. The rotation speed displayed on the speedometer 50 is as shown in Fig. 3A.
As shown in FIG.

Even if the continuous operation switch 62 is turned on while the continuous operation preparation relay 54 is not energized, the continuous operation relay 56 will not have its energized circuit connected to contact 5.
4b, so no current is applied.

Next, when the continuous operation preparation switch 60 is turned on, the continuous operation preparation relay 54 is energized through its normally open contact 60a, so the first contact 54a is opened and the variable resistor 52 is connected to the control circuit 44. , the motor 36 is rotated at a value determined by the variable resistors 48,52.

After that, within a certain period of time, the continuous operation switch 62
If not turned on, the continuous operation preparation relay 54 is de-energized and the first contact 54a is closed, so the motor 36 is rotated at a speed determined by the variable resistor 48.

However, if the continuous operation switch 62 is turned on within a certain period of time after the continuous operation preparation switch 60 is turned on, the clutch 34 is engaged, the continuous operation relay 56 is energized, and the second contact 56a is opened. Therefore, the motor 36 has variable resistors 48 and 52.
It rotates at the normal speed determined by . The actual rotational speed of the motor 36 at this time is displayed on the speedometer 50, and the value is the same as the value indicated by the indicator 65 and scale plate 68 as shown in FIG. 3B.

According to the press machine 10, the motor 3 during continuous operation
Since it is only necessary to set the rotation speed of motor 3 while looking at the value indicated by the indicator 66 and the target plate 68,
Anyone can easily set the rotation speed of 6 to the correct value. Further, a continuous operation preparation switch 60 is provided, and when the switch is turned on, the rotation speed of the motor 36 is switched to the value when a load is applied to the motor, so that the stroke of the slide becomes a predetermined value from the beginning. .

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of a press machine, FIG. 2 is a diagram showing an embodiment of an electric circuit of a control device of the present invention, and FIG. 3 is a diagram showing an operation panel. 10: Press machine, 36: Motor, 42: Speed control device, 44: Control circuit, 46: Switching circuit, 4
8, 52: Variable resistor, 54, 56: Relay, 5
4a, 56b: first and second contacts, 60, 6
2: first and second switch, 64: knob,
66: indicator, 68: scale plate, 70: scale.

Claims (1)

[Scope of Claims] 1. A speed control device for a press using a speed-changeable electric motor as a drive source for reciprocating a slide, the speed control device controlling the rotation speed of the electric motor during continuous operation and during no-load operation. a switching means for switching to a different value at a speed, a speed setting means for setting the rotation speed of the electric motor, and a control means for controlling the rotation speed of the electric motor based on information of the switching means and the speed setting means, The speed setting means includes a variable resistor having a knob for setting the rotation speed of the electric motor, and a scale disposed near the knob to indicate the rotation speed of the electric motor during continuous operation in conjunction with the knob. A speed control device for a press machine, comprising a scale plate with an attached scale plate. 2. The speed control device for a press machine according to claim 1, wherein the variable resistor is electrically connected to the control means via the switching means. 3. Claims: The variable resistor is a rotary variable resistor that sets the rotation speed by angularly rotating the knob, and the scale is provided along the rotation locus of the knob. The speed control device for a press machine according to item 1 or 2. 4. A speed control device for a press using an electric motor whose speed can be changed as a drive source for reciprocating the slide, which switches the rotational speed of the electric motor to different values during continuous operation and during no-load operation. a speed setting means for setting the rotation speed of the electric motor; and a control means for controlling the rotation speed of the electric motor based on information of the switching means and the speed setting means, the speed setting means comprising: a variable resistor having a knob for setting the rotation speed of the electric motor; and a scale plate arranged near the knob and having a scale indicating the rotation speed of the electric motor during continuous operation in conjunction with the knob. The switching means includes a first switch for switching the rotation speed of the electric motor to a value for continuous operation before the press machine is operated continuously, and a first switch for switching the rotation speed of the electric motor to a value for continuous operation, and a switch for switching the rotation speed of the electric motor to a value for continuous operation before the press machine is operated continuously. A speed control device for a press machine, comprising a second switch for continuously operating the press machine. 5. The switching means includes a first contact that opens for a certain period of time after the first switch is operated;
a second contact that opens when the second switch is operated while the first contact is open; and a second contact that is connected in parallel to the first and second contacts. The speed control device for a press machine according to claim 4, further comprising a variable resistor. 6. The speed control device for a press machine according to claim 4, wherein the switching means and the speed setting means are connected to the control means.