JP3461927B2 - Bending device with power regeneration device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bending device provided with a power regeneration device. 2. Description of the Related Art It is well known that when a servomotor is used as a drive source of various machine tools, regenerative braking by a servomotor is used when a driven body is decelerated and stopped. FIG. 4 shows an example of a general drive control circuit of a servomotor used as a drive source of a machine tool. The configuration of the drive control circuit 100 for a servomotor is such that a converter section 103 for converting a three-phase AC (R, S, T) power supply 101 to DC, and this converter section 103
Unit 105 that converts the direct current obtained in step into alternating current
And the PWM (Pul
se Width Modulation) control circuit unit 107, servo motor 109 and power regeneration control circuit unit 1
11 and the like. The converter section 103 comprises a rectifier circuit using six diodes in a bridge form and a current smoothing capacitor, and the inverter section 105 comprises a bridge circuit comprising six power transistors. I have. The six power transistors of the inverter unit 105 are turned on and off by the PWM control circuit unit 107, and the U, V, and W phase currents and voltages input to the servo motor 109 are appropriately adjusted with a phase difference of 120 degrees. Under the control, the number of rotations, rotation speed, rotation direction, and the like of the servo motor 109 can be arbitrarily controlled. Diodes are inserted in parallel into the six power transistors of the inverter unit 105, respectively, and a bridge circuit is formed by the six diodes. The rotation of the servomotor 109 is transmitted via a transmission mechanism (not shown) to a driven body of a machine tool, for example, a ram of a bending apparatus, and the driven body (ram) reciprocates. Can be The power regeneration control circuit section 111 includes a switching transistor controlled by the power regeneration control circuit 113, and a regenerative resistor 115 inserted in series with the switching transistor to consume regenerative power. [0006] A conventional servo motor drive control circuit is constructed as described above, and this drive control circuit is used as regenerative braking when a driven body of a machine tool is decelerated or stopped. The servo motor 109
Back electromotive force, that is, a current is generated. The generated current is rectified by six diode bridges inserted in parallel with the six power transistors of the inverter unit 105, and the regenerative control circuit 1 of the power regenerative control circuit unit 111
13 is consumed by the regenerative resistor 115 as heat energy. When the drive control circuit of the servomotor described above is used in the bending apparatus according to the present invention, acceleration / deceleration or stop operation of the driven body of the bending apparatus is frequently performed. Since the moment of inertia of the driving body is also large, the amount of energy consumed as heat energy in the regenerative resistor becomes considerably large, and the regenerative resistor may be overheated and destroyed. Therefore, a large-capacity regenerative resistor is required, and at the same time, a fan or the like is required for cooling the regenerative resistor, which requires additional mounting space and raises the cost. There is also a problem that heat generated by the regenerative resistor is transmitted to surrounding mechanical components and adversely affects the accuracy of the machine. Further, in a screw driving type bending apparatus which controls reciprocation of a ram by a servomotor, a ram drive system becomes more complicated than a bending apparatus using hydraulic pressure as a driving source of the ram. There is a problem in that the moment of inertia of the driven body also increases, which requires extra driving energy and increases the electricity cost. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in a bending apparatus using a servomotor as a drive source of a ram, the generation of heat generated at the time of regenerative braking of the servomotor is minimized. It is an object of the present invention to provide a bending device provided with a power regeneration device that is held down. It is another object of the present invention to provide a bending apparatus provided with a power regenerating apparatus which does not have a thermal effect on a machine due to heat generated by regenerative power consumption. Further, it is an object of the present invention to provide a bending apparatus provided with a power regenerating apparatus which consumes regenerative power and saves energy. [0012] In order to achieve the above object, a bending apparatus provided with a power regeneration device according to the present invention comprises:
In bending device of the screw drive system for controlling the reciprocation of the ram by the servo motor, provided power regeneration device for returning regenerative power generated in the servo motor during regenerative braking of the servo motor to the power source side, said power regeneration device Is from the AC power supply
A converter for converting the AC power into DC, and
The first input which is inversely converted to AC and supplied to the servomotor
A inverter and a PWM control circuit for controlling the first inverter
The regenerative power is supplied to the servo amplifier composed of
The second inverter, which converts it back to power and returns it to the power supply,
It is a combination . The bending apparatus provided with the power regenerating device of the present invention has the above-described configuration, so that there is almost no heat generation due to consumption of regenerative power in the servo amplifier 43. In addition, a regenerative resistor for regenerative power consumption and a cooling device for regenerative resistor cooling, for example, a component such as a fan and a drive motor for the fan have become unnecessary. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a bending apparatus provided with a power regeneration device of the present invention. FIG. 1 is a perspective view schematically showing the entire bending apparatus 1. In FIG. 1, upper and lower molds and a material positioning device, which are tools for bending a sheet metal material, are not shown. The bending apparatus 1 is provided with a lower table 5 for supporting a lower mold (not shown) at the front lower portion of both side frames (3, 3) having a C shape, and an upper position of the lower table 5. Is provided with an upper table 7 for supporting an upper die (not shown) corresponding to the lower die. In the bending apparatus 1, a sheet metal material positioned and placed between a bending mold (a punch and a die (not shown)) attached to the lower table 5 and the upper table 7 is transferred to the lower table 5 or the lower table 5. One of the upper tables 7 is moved up and down, pressed and held, and bent. In the present embodiment, the upper table 7 is shown as moving up and down. Therefore, in this embodiment, the upper table 7 corresponds to a reciprocating ram. The upper table 7 is configured so that the left and right sides can be moved up and down in parallel by a guide mechanism (not shown) provided on a connecting plate 9 attached to the upper front of the side frames on both sides. In order to move the upper table (ram) 7 up and down, ram driving devices 11 are provided on both sides of the side table 3. Since the structure of the both-side ram drive device 11 is the same, the right ram drive device 11 shown in FIG. 1 will be described. The ram driving device 11 includes a servo motor 13 for moving the upper table 7 up and down.
The ball screw 15 is driven to rotate. The upper end of the ball screw 15 is rotatably screwed into a ball nut 17 mounted on the back side of the upper table (ram) 7, and the lower end of the ball screw 15 is a bearing member mounted below the side frame 3. 19 rotatably supported. Further, a pinion gear 23 is attached to the output shaft 21 of the servo motor 13, and the pinion gear 23 is engaged with a gear 25 attached to the ball screw 15. In the above configuration, when the servo motor 13 is driven to rotate, for example, when the servo motor 13 is driven to rotate forward, the upper table 7 (ram) moves downward, and when the servo motor 13 is driven to rotate reversely, the upper table 7 moves upward. caution its <br/> by name to move to. The ram driving devices 11 on both sides are always driven synchronously. Therefore, the upper table 7
Means that the left and right move up and down in parallel. FIG. 2 shows an example of a block diagram of a control device of a bending device provided with a power regeneration device of the present invention. The control device 31 schematically shows the function of the CNC device 31 for numerically controlling the bending device 1 and does not detail the internal functions of the CNC device. The CNC device 31 includes a numerical calculation unit 33 that calculates various commands according to a program, an input device 35 including a keyboard and a CRT, and the like.
Interface 37 for input / output signals between device 31 and the outside
And a shaft control unit 3 for controlling a positioning device and other drive shafts
9 and a high-power section 41. [0022] processing the output device 35 of the CNC device 31 Puraguramu is input to the CNC device 31, CN
The C device 31 performs necessary numerical calculations in the numerical operation unit 33 and outputs appropriate commands to the axis control unit 39 in order to issue appropriate commands to the axis control unit 39 to execute the machining program. . Command from the axis control unit 39 a servo motor 13 is given to the servo motor 13 is amplified in the servo amplifier 43 is driven to rotate accordingly. Note that a three-phase AC power supply is connected to the servo amplifier 43 from the high-power section 41. FIG. 3 shows details of the servo amplifier 43 and the power regeneration device 44. This servo amplifier 43
And the configuration of the power regeneration device 44 is a three-phase alternating current (R, S,
T) a converter unit 47 for converting the power supply 41 into a direct current,
A first inverter 49 for converting the DC obtained by the converter 47 into an AC, a PWM control circuit 51 for controlling the first inverter 49, and outputs (U, V) of the first inverter 49. , a servo motor 13 connected to W), and a like second inverter 53 and a regeneration control circuit 55. The servo motor 13
Can be used with either an AC servomotor (also called a brushless DC servomotor) or a DC servomotor. The converter section 47 is composed of a rectifier circuit using six diodes in a bridge shape and a current smoothing capacitor. The first inverter section 49 is composed of a bridge circuit composed of six power transistors. ing. The six power transistors of the first inverter unit 49 are on / off controlled by the PWM control circuit unit 51, and the output is input to the servo motor 13 . It should be noted that the PWM control circuit section 51 can use a well-known PWM control circuit section, and thus details are omitted. In the first inverter unit 49, the DC power from the converter unit 47 is a three-phase AC, and the current and voltage of the three-phase AC output (U, V, W) are appropriately controlled.
The rotation speed, rotation speed, rotation direction, and the like of the servo motor 13 can be arbitrarily controlled. Further, diodes are inserted into the six power transistors of the first inverter unit 49 in parallel with the polarity opposite to the current DC-converted by the converter unit 47, respectively. A bridge circuit is constituted by the diodes. That is, when the first inverter unit 49 is controlled by the PWM control circuit 51 to apply regenerative braking to the servo motor 13 , the diode bridge circuit of the first inverter unit 49 converts the three-phase AC generated in the servo motor 13 into DC. Acts as a rectifier. When the driven body of the machine tool (corresponding to the upper table (ram) 7 in the present embodiment) is decelerated or stopped, the first inverter 49 of the PWM control circuit 51 of the servo motor 13 is used as regenerative braking. When the regenerative power, that is, the back electromotive force and the current are generated in the servo motor 13 ,
The voltage and the current are converted to DC by the diode bridge circuit of the first inverter unit 49 as described above, and are input to the second inverter unit 53. This second inverter unit 53
Is composed of six thyristor bridge circuits and is controlled by the regeneration control circuit 55. This regenerative control circuit 55
The phase of the voltage or current of the three-phase AC power supply 41 is detected, and the phase of the voltage or current of the regenerative electric power is detected.
Is converted into a three-phase alternating current in synchronization with the phase of the voltage or current and is returned to the power supply 41. According to the present invention having the above-described structure,
Since no regenerative electric power is consumed in the servo amplifier, the heat influence on the machine due to the heat generated by the servo amplifier is reduced, and the cost is reduced because components such as the regenerative resistor and its cooling device are not required. There is also a space advantage such as a compact servo amplifier. Further, returning the regenerative power to the power supply side has the effect of saving energy.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall schematic view of a bending apparatus provided with a power regeneration device of the present invention. FIG. 2 is an example of a block diagram of a control device of a bending device provided with the power regeneration device of the present invention. FIG. 3 is an embodiment of a power regeneration device according to the present invention. FIG. 4 is an example of a general drive control circuit of a servomotor used as a drive source of a machine tool. [Description of Signs] 1 Bending device 3 Side frame 5 Lower table 7 Upper table 11 Ram drive device 13 Servo motor 15 Ball screw 41 AC power supply 43 Servo amplifier 44 Power regeneration device 47 Converter 49 First inverter 51 PWM control circuit 53 2 inverter 55 Regenerative control circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B21D 5/02 B30B 15/14 H02P 3/18 H02P 7/63

Claims (1)

(57) [Claim 1] In a screw drive type bending apparatus which controls reciprocation of a ram by a servomotor, a regenerative electric power generated in the servomotor during regenerative braking of the servomotor is supplied to a power supply. power regeneration device for returning to the side provided, said power regeneration device
Is a converter that converts AC power from AC power supply to DC
And reversely converts the DC to AC and supplies it to the servomotor.
A first inverter to be supplied and controlling the first inverter
The servo amplifier comprising the PWM control circuit
The second step in which raw power is converted back to AC power and returned to the power supply side
A bending device provided with a power regenerating device characterized by combining two inverters .