JP2000061788A - Drive device of motor in centerless grinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain high grinding accuracy and improve energy efficiency by providing an inverter recovering regenerated electric power from a regulating wheel motor through an inverter circuit. SOLUTION: An inverter circuit 21 is formed into a bidirectional type, and regenerated electric power from a regulating wheel motor Mr is recovered by an inverter 10. Namely, AC power Pr to the regulating wheel motor Mr flows from the inverter circuit 21 to the regulating wheel motor Mr side in a positive sign when the regulating wheel motor Mr drives a regulating wheel RW and flows from the regulating wheel motor Mr to the inverter circuit 21 side in a negative sign when the regulating wheel motor Mr brakes the regulating wheel RW. Consequently, at braking of the regulating wheel motor Mr, the inverter 10 reutilizes the regenerated electric power P=-Pr recoverd through the inverter circuit 21 as one part of AC power Pg against a grinding wheel motor Mg, and AC power Ph from a commercial power supply line is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device for a centerless grinding machine capable of maintaining high grinding accuracy and improving energy efficiency.

[0002]

2. Description of the Related Art When a surface of a work W having a cylindrical shape or a cylindrical shape is ground with high accuracy, a centerless grinding machine is sometimes used (FIG. 3).

The centerless grinder includes a grinding wheel GW and an adjusting wheel RW.
Are arranged substantially in parallel, and a blade B for supporting the work W is erected between the grinding wheel GW and the adjusting wheel RW. The grinding wheel GW is connected to the grinding wheel motor Mg via the belt Mg1, and the adjusting wheel RW is connected to the belt Mr1.
Is connected to the adjusting vehicle motor Mr via. Therefore,
In this case, the work W is set between the grinding wheel GW and the adjusting wheel RW, and the grinding wheel GW is rotated in the direction of arrow K1 and the adjusting wheel RW is rotated in the direction of arrow K2, so that the work W is moved in the direction of arrow. The surface of the work W can be precisely ground by the grinding wheel GW while being fed in the axial direction on the blade B while rotating in the K3 direction.

Generally, the grinding wheel GW is rotationally driven so as to have an optimum peripheral speed determined by the size and material of the work W, and the adjusting wheel RW is rotated so as to have a peripheral speed slower than that of the grinding wheel GW. To drive. The adjusting vehicle RW is the work W
In order to apply an appropriate braking force to the regulated vehicle motor, it is common to interpose a worm gear type speed reducer between the regulated vehicle motor Mr and a regenerative resistor attached to the inverter that feeds the regulated vehicle motor Mr. is there.

[0005]

According to the prior art, since the worm gear type speed reducer is indispensable to be mounted on the machine frame, heat is generated and the grinding accuracy of the work is deteriorated. In addition, the regenerative resistor cannot effectively reuse the regenerative power from the regulated vehicle motor, which is not energy efficient.
There was a problem that the air conditioning efficiency in the factory was deteriorated.

Therefore, in view of the problems of the prior art, an object of the present invention is to connect an inverter for supplying power to a grinding wheel motor with a branch and to provide an inverter circuit for supplying power to a regulating wheel motor, thereby maintaining high grinding accuracy. An object of the present invention is to provide a motor drive device in a centerless grinding machine capable of improving energy efficiency.

[0007]

The structure of the present invention for achieving the above object is such that a forward conversion section and an inverse conversion section are cascaded,
It is equipped with an inverter that supplies power to the grinding wheel motor and a bidirectional inverter circuit that branches and connects to the input side of the inverse conversion unit and supplies power to the adjustment vehicle motor. The gist is to recover the regenerative power of.

The inverter circuit can control the speed of the regulated vehicle motor through the speed detector, and can perform the vector control of the regulated vehicle motor.

Further, the inverter may be a voltage type inverter.

[0010]

According to the structure of the invention, since the bidirectional inverter circuit for feeding the adjusting wheel motor is branched and connected to the input side of the inverse conversion unit, the inverter for feeding the grinding wheel motor is connected via the inverter circuit. The regenerated electric power from the adjusting wheel motor can be recovered and reused as a part of the electric power for driving the grinding wheel motor. Further, the forward conversion unit of the inverter can be shared by the reverse conversion unit itself and the inverter circuit.

By controlling the speed of the regulated vehicle motor, the inverter circuit can control the regulated vehicle motor to rotate at a constant speed regardless of the load fluctuation of the regulated vehicle.

The inverter circuit can further improve the speed control performance of the regulated vehicle motor by performing vector control of the regulated vehicle motor. In addition, vector control is
The speed control characteristic equivalent to that of the DC motor is realized by separately controlling the primary current of the regulated vehicle motor into the excitation component and the torque component. Vector control includes magnetic flux detection type vector control and slip frequency type vector control in order to obtain the phase difference between the internal magnetic flux of the motor and the secondary current. Is better.

If the inverter is a voltage source inverter,
The inverter can act as a constant voltage source when viewed from the grinding wheel motor side, and is not affected by the output voltage even if the load on the grinding wheel motor fluctuates. Can be operated stably.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The motor driving device in the centerless grinding machine comprises an inverter 10 and a bidirectional inverter circuit 21 (FIG. 1). However, the inverter 10 supplies power to the grinding wheel motor Mg, and the inverter circuit 21 supplies power to the adjusting wheel motor Mr.

The inverter 10 comprises a forward conversion section 11 and an inverse conversion section 12 which are connected in series. The input side of the forward conversion unit 11 is connected to the three-phase commercial power supply line L,
A large-capacity smoothing capacitor C is connected to the output side. Therefore, the inverter 10 is formed as a voltage source inverter. The inverter 10 includes the forward conversion unit 1
The three-phase electric power Ph from the commercial power supply line L is converted into the DC electric power through 1 and the DC electric power is converted into the AC electric power Pg through the inverse conversion unit 12 and supplied to the grinding wheel motor Mg to thereby supply the grinding wheel motor. The grinding wheel GW can be rotationally driven via the motor Mg.

The inverter circuit 21 is branched and connected to the input side of the inverse conversion unit 12 of the inverter 10. The inverter circuit 21 is fed with a feedback signal Sf from a speed detector TG which detects the rotation speed of the regulated vehicle motor Mr. Therefore, the inverter circuit 21 converts the DC power from the forward conversion unit 11 of the inverter 10 into the AC power Pr and supplies the AC power Pr to the regulated vehicle motor Mr, thereby rotationally driving the regulated vehicle RW via the regulated vehicle motor Mr. be able to.

The inverter circuit 21 can control the speed of the regulated vehicle motor Mr by vector control based on the feedback signal Sf from the speed detector TG. Further, the inverter circuit 21 is formed in a bidirectional type, and the regenerative electric power from the regulated vehicle motor Mr can be collected in the inverter 10.

That is, when the regulated vehicle motor Mr drives the regulated vehicle RW, the AC electric power Pr to the regulated vehicle motor Mr takes a positive sign and flows from the inverter circuit 21 to the regulated vehicle motor Mr side. When the regulated vehicle RW is braked, it takes a negative sign and flows from the regulated vehicle motor Mr to the inverter circuit 21 side. Therefore, the inverter 1
0 recycles the regenerative electric power P = -Pr recovered via the inverter circuit 21 as a part of the AC electric power Pg to the grinding wheel motor Mg when the regulated vehicle motor Mr is being braked, and the AC from the commercial power line L is used. Power Ph = Ph = Pg
Can be reduced to −Pr.

In the above description, the inverter circuit 21
The input side can be branched and connected to the inverter 10 and the battery BT via the charge / discharge controller 22 (FIG. 2). The charge / discharge controller 22 operates so as to charge the battery BT with the regenerative power from the inverter circuit 21 when the power unit price of the commercial power line L fluctuates depending on the time zone, and when the power unit price is low, the power unit price is high. At this time, the discharge power from the battery BT, the inverter circuit 2
Inverter 1 of inverter 10 receives both regenerated electric power from
By operating so as to send to the No. 2, it is possible to reduce the overall power consumption cost.

[0021]

As described above, according to the present invention, by combining the inverter for feeding the grinding wheel motor and the inverter circuit branch-connected to the input side of the inverse conversion section of the inverter, the inverter can be The regenerated electric power from the adjusting wheel motor can be recovered via the circuit and effectively reused for driving the grinding wheel motor, improving the energy efficiency as a whole and eliminating unnecessary heat generating elements for the work. There is an excellent effect that high grinding accuracy can be maintained.

[Brief description of drawings]

[Figure 1] Overall configuration block diagram

FIG. 2 is a block diagram of a main part showing another embodiment.

[Fig. 3] Schematic diagram of centerless grinding machine

[Explanation of symbols]

Mg ... Grinding wheel motor Mr ... Adjusting car motor TG ... Speed detector 10 ... Inverter 11 ... Forward conversion unit 12 ... Inverse conversion unit 21 ... Inverter circuit

Claims (4)

[Claims] 1. A forward conversion unit and a reverse conversion unit are cascaded to supply an electric power to a grinding wheel motor, and an inverter circuit bidirectionally connected to the input side of the reverse conversion unit to supply electric power to a regulated vehicle motor. A drive device for a motor in a centerless grinding machine, characterized in that the inverter recovers regenerative electric power from a regulated vehicle motor via the inverter circuit. 2. The motor drive device for a centerless grinding machine according to claim 1, wherein the inverter circuit controls the speed of the adjusting wheel motor through a speed detector. 3. The motor driving device in a centerless grinding machine according to claim 2, wherein the inverter circuit vector-controls a regulated vehicle motor. 4. The motor driving device in a centerless grinding machine according to claim 1, wherein the inverter is a voltage source inverter.