JPH0373243A - Main shaft positioning method - Google Patents

Abstract

PURPOSE:To restrain severe changes in speed and prevent gear noise by changing a limit value corresponding to a deviation amount between a commanded stop position and a current position in positioning from a stop state to a position commanded by a stop position command. CONSTITUTION:A limit value of a limiter 6 is changed corresponding to a deviation between a target stop position and a current value. That is, a maximum limit value and a deviation limit value are given from the outside as parameters etc., and a speed command limit value for a deviation (an initial deviation amount in positioning a main shaft) to a given target value is found by a preset equation. Using this limit value causes the speed command limit value to be also changed corresponding to the deviation and not to be excessively lowered, therefore allowing severe changes in speed to be restrained against a given torget value and gear noise to be suppressed. Especially in positioning from a stop state, a torque command is once turned from positive to zero in the point that a real speed matches to the speed command limiter and then turned into negative so that no gear noise takes place.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for positioning a spindle in a machine having gears, which aims to suppress gear noise generated when positioning the spindle.

[Conventional technology]

FIG. 5 is a block diagram showing the configuration of a conventional positioning control system for a machine having a variable speed gear. In the figure, 1 is a main shaft motor, 2 is a main shaft, and a speed change gear 3 for decelerating the rotation of the main shaft motor 1 is provided between the two. When the target stop position is given as a command, the deviation θ between the target stop position and the current position of the spindle detected by the pulse generator 4 multiplied by the position gain is given to the speed control device 5 as a speed command. , the main shaft motor 1 is driven.

Now, in a machine having such a gear 3 for speed change between the spindle motor l and the spindle 2, when positioning the spindle 2, the spindle 2 is moved from a stopped state to a commanded position. When the positioning operation is performed, the main shaft 2 performs an operation of accelerating once and then decelerating. At the time of transition from the acceleration state to the deceleration state, gear noise is generated due to the backlash of the gear 3. One way to suppress the occurrence of such gear noise is to install a limiter 6 as shown in Figure 5 to limit the magnitude of the speed command so that it does not exceed a certain value (limit value). Restrictions are being taken.

[Problem to be solved by the invention]

Incidentally, in recent years, there has been an increasing demand for stopping the spindle 2 at any position or at multiple points. For example, when a machine is used for a lathe, etc., and a loader such as a robot is used to load and unload the workpiece, it is necessary to stop the workpiece at a predetermined position to align the loading and unloading direction after processing the workpiece. There is. In addition, when tapping four locations on a workpiece, the spindle is rotated 90 degrees at a time, and the workpiece is stopped there for machining.

In such a case, if you try to position from a stopped state using the position control device with the configuration shown in Figure 5, the limit value of the speed command is constant, so if the deviation θ between the target value and the current value is large, As shown in Fig. 6, the speed command is limited by applying the speed limit value, but as the deviation θ between the target value and the current value becomes smaller, the speed when changing from the acceleration state to the deceleration state also becomes smaller. As shown in FIG. 7, the speed command value no longer applies to the speed limit value, and gear noise may occur.

In this way, when it is necessary to stop the spindle at an arbitrary position or at multiple points, even if the speed command is limited to a certain limit value, if the amount of movement differs, the speed at the time of transition from acceleration to deceleration will change. Due to the different amounts of movement, gear noise may occur depending on the amount of movement. In that case, the gear noise can be prevented by reducing the limit value or the position loop gain, but the positioning time will become longer.

The present invention is intended to improve the above-mentioned conventional problems, and its purpose is to suppress the gear noise generated when arbitrarily positioning the main shaft from a stopped state without prolonging the positioning time.

[Means to solve the problem]

In order to achieve this objective, the spindle positioning method of the present invention applies a position loop gain of the drive system of the machine to the amount of deviation between the current position and an arbitrary stop position command given from the outside of the drive system of the machine having gears. In a positioning control device that uses the multiplied value as a speed command for the inverter that constitutes the drive system and is equipped with a limiter that limits the value of the speed command to a certain limit value, the position commanded by the stop position command from a stopped state When positioning, the limit value is changed according to the amount of deviation between the stop position command and the current position, thereby suppressing a sudden change in speed and preventing gear noise.

[Effect]

In the present invention, the limit value that limits the maximum value of the speed command is not set fixedly, but is changed depending on the amount of deviation between the stop position command and the current position.

Thereby, even when positioning to an arbitrary position from a stopped state, gear noise can be suppressed regardless of the magnitude of the deviation amount.

〔Example〕

Hereinafter, the present invention will be specifically explained based on Examples.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. The difference between this embodiment and the conventional example shown in FIG. 5 is that instead of using a fixed value as the limit value of the limiter 6, the limit value is changed according to the deviation θ between the target stop position and the current value. be.

As mentioned above, the maximum value (initial value) of the speed command is the product of the deviation θ and the position loop gain, so it can be seen that if the position loop gain is constant, it is proportional to the amount of deviation.

Therefore, in the present invention, a limiter 6 having characteristics as shown in FIG. 2 is used as a limit value of the speed command. The maximum limit value N□ and the deviation limit value θ□8 in the figure are given from the outside as parameters. The speed command limit value N of the deviation θ (initial deviation amount during spindle positioning) with respect to a certain arbitrary target value can be expressed by the following equation.

7'J = N * a X Xθ, /θ, ・
... (1) If the limit value in the above formula is used, the speed command limit value will change according to the deviation, and the +7 limit value will not be lowered too much, so there will be no sudden change in speed with respect to any target value. In addition to suppressing gear noise, positioning can be done without taking any longer than necessary.

3 and 4 show the speed command, actual speed, and torque command when positioning is performed from a stopped state.

However, FIG. 3 shows the case where the limiter 6 is not provided, and FIG. 4 shows the case where the limiter 6 is inserted. If there is no speed command 'J Mitsutaro, gear noise will occur at point a where the torque command switches from positive to negative as shown in FIG. When a speed command IJ limiter is installed, as shown in Figure 4, the torque command temporarily becomes zero at point b where the actual speed matches the speed command limiter, and at the 0 point the torque command becomes negative, so the gear noise is reduced. Does not occur.

〔Effect of the invention〕

As described above, according to the present invention, the limit value of the limiter is changed according to the deviation between the target stop position and the current value, so when stopping at an arbitrary target stop position or at multiple points, However, gear noise can be suppressed and positioning can be performed without extending the time unnecessarily.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG.
The figure shows the characteristics of the limiter according to the present invention, Figure 3 is a waveform diagram of the speed command, actual speed, and torque command when the speed command limiter is not provided, and Figure 4 is the speed when the speed command limiter is provided. Waveform diagram of command, actual speed, and torque command, 5th
The figure is a block diagram showing the conventional configuration of a spindle positioning device with gears, Figure 6 is an explanatory diagram of a speed command of a magnitude that exceeds the speed limit value, and Figure 7 is an explanatory diagram of a speed command of a magnitude that does not exceed the speed limit value. It is an explanatory diagram. 1: Main shaft motor 2: Main shaft 3: Speed change gear 4: Pulse generator 5: Speed control device 6: Limiter

Claims (1)

[Claims] 1. The drive system is calculated by multiplying the deviation amount between the current position and any stop position command given from the outside of the drive system of a machine having gears by the position loop gain of the drive system of the machine. In a positioning control device equipped with a limiter that is used as a speed command for an inverter constituting the inverter and limits the value of the speed command to a certain limit value, when positioning from a stopped state to a position commanded by a stop position command, A method for positioning a spindle, characterized in that the limit value is changed according to the amount of deviation between a stop position command and a current position, thereby suppressing a sudden change in speed and preventing gear noise.