JPS62188620A - Controlling method of table shaft for nc hobbing machine - Google Patents

Abstract

PURPOSE:To aim at improvement in machining accuracy, by detecting a traveling state of an axial shaft of a numerically controlled hobbing machine fitted with a numerically controlled index shaft and the axial shaft, and controlling the revolving speed of a table shaft according to the specified condition. CONSTITUTION:An encoder 1 detects an amount of travel in an axial shaft 30 which is driven for rotation by a drive motor 6 via gears 2a and 2b, rotating and driving an axial feed screw 3. In this connection, in an edge of this drive motor 6, there is a speed-position detector 7. Output of the encoder 1 is operated by a control circuit, whereby speed compensation for a drive motor 13 is carried out, and a table 9 and a work 8 are rotated and driven at the specified speed by way of gears 12a and 12b, a master work 11 and a worm wheel 10. And, since a synchronous relationship between a feed rate of the shaft 30 and a revolving speed of a table shaft is kept up, even if working conditions are varied, there is no time lag and the table shaft is made controllable in a real time manner.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for controlling a table shaft for an NC hobbing machine.

<Conventional technology> An NC hobbing machine that processes helical gears.
÷-pu'jiru+putr+ro11! ;'sk 111
:t When driving with the same tune, the relationship shown in the following equation must be satisfied.

Here, Fh is the number of command pulses to the table drive motor during helical gear machining, f is the axial feed (+sm/rema), β is the helical gear helix angle (degree), and Z is the number of workpiece teeth. .

mn is normal module (mm), g is the hob thread number.

Incidentally, the decoding symbol for σ in the above equation (1) is determined by the torsion direction of the workpiece, the direction of axial feed, and the torsion direction of the hob.

By the way, in the conventional NC hobbing machine, the relationship of equation (1) is based on the pulse distribution method f to the indexing axis and the axial axis. In other words, the axial pulse aFa based on the indexing pulse number Fh of −U and the axial feed f in equation (1) is (
1) It was given so that the relationship of equation was satisfied.

<Problems to be Solved by the Invention> However, according to the above method, when the condition of axial feed f=0 in machining helical gears, a machining state called radial cut, in which cutting is performed only in the radial direction, occurs. In this case, it is necessary to replace the arithmetic expression with the following expression.

g g Fh = 360 (1 ± 0) - = 360 and must be controlled to satisfy this relationship.

In order to maintain this relationship, it is necessary to keep the axial feed f constant in the NC hobbing machine, but in consideration of machining efficiency, a large axial feed fl is given in the rough machining area as shown in FIG.

By the way, in the generation region, the axial feed f must be kept constant, but this is because there is no control loop between the axial axis and the table axis, so the speed of the axial feed f must be commanded in advance. However, in anticipation of this speed, the table axis is corrected based on the relationship of equation (1) above. For this reason, if the axial feed f changes from fl to f2 in the generation area, for example, as shown in FIG. 3, axial lead defects are likely to occur at this boundary A.

The present invention has been made in view of the above-mentioned problems, and its object is to provide a method of controlling a table axis for an NC hobbing machine that can improve machining accuracy.

Means for Solving Problems> In order to achieve the above object, the present invention provides a position detector installed in the drive motor of the axial axis of an NC hobbing machine equipped with an NC indexing axis and an axial axis. By controlling the rotational speed of the table shaft in real time according to predetermined conditions based on the data, a synchronous relationship between the scheduled axial shaft feed speed and the rotational speed of the table shaft can be maintained.

As mentioned above, the synchronous relationship between the axial axis feed rate and the rotation speed of the table axis is maintained, so no matter how the machining conditions change, the table axis can be adjusted in real time without any time delay. Control becomes possible, and processing accuracy can be improved.

Embodiments The embodiments of the present invention will be explained below based on the attached drawings.

FIG. 1 is a block diagram showing the configuration of an apparatus for carrying out the method of the present invention, and FIG. 2 is a block diagram showing the configuration of a control circuit for a reversible neck.

In FIG. 1, l indicates an axial shaft 30. The transfer shaft 30 is rotationally driven by a drive motor 6 via gears 2a and 2b, and rotationally drives the axial feed screw 3. Note that a speed/position detector 7 is provided at the end of the drive motor 6.

By rotating the axial feed screw 3 above, the hob head
The hob saddle 4 moves, and this hob head - hob saddle 4
A hob cutter 5 is attached to the top. Meanwhile, in FIG. - A position detector 14 is provided. The master worm 11 is meshed with the worm wheel lO, and the rotation of the master worm 11 causes the worm wheel lO to engage with the worm wheel lO.
O, and the table 9 and workpiece 8 which are integrally attached to the worm wheel 10 are driven to rotate.

Therefore, the output of encoder 1 is shown in Figure 2.
L 2'1M book 9 missing Thereafter, the table 9 and the workpiece 8 are rotated at a predetermined speed.

Here, the control circuit will be explained based on Fig. 2. In the figure, ■ is an encoder installed on the axial shaft 30 (see Fig. 1), and when the axial shaft 30 rotates, the encoder This device generates pulses 21 according to the amount of movement of the axial shaft 30. Incidentally, when the axial shaft 30 rotates, the hob cutter 5 of the hob head/hob saddle 4 shown in FIG. 1 moves, for example, up and down.

The output 21 of the encoder 1 is input to the pulse quadrupling circuit 18, where the axial movement amount of 17zm is adjusted to correspond to one pulse, and the axial movement direction is also detected. The output 21 of this pulse quadrupling circuit 1B is a binary rate multiplier (BRM) 17.
Here, the number of pulses is adjusted to be smaller than the number of pulses instructed by the arithmetic processing unit (CPU) 20.

On the other hand, the CPU 20 calculates based on the above formula (1),
The BRM17 uses this result as bit pattern data 22.
send to Then, the pulse train Fh corresponding to equation (1) is B
RMI? This pulse train Fh is output to the pulse direction selection circuit 18. Since this pulse direction selection circuit 18 separately receives an up or down command from the CPU 20, it outputs in the correct direction based on this information.

Further, the pulse train 21 outputted from the pulse direction selection circuit 18 is input to the table axis motor drive amplifier 7'19, where a current value replaced with the motor speed is created based on the pulse train 21, and this current value is amplified. Finally, the servo motor 13 is driven based on the output of the table shaft motor drive amplifier 19, and the differential amount is correctly applied to the table in accordance with the axial movement.

FIG. 3 shows a modified embodiment of the present invention, in which the encoder 1 is directly installed on the drive motor 6, and the other configuration is the same as that of the first embodiment (shown in FIG. 1). The same is true.

<Effects of the Invention> As is clear from the above explanation, according to the present invention, the rotational speed of the table axis is controlled by detecting the movement state of the axial axis, so no matter how the machining conditions change, the time The table axis can be controlled without delay, improving machining accuracy. Furthermore, by applying the method of the present invention, adaptive control is also possible.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a device for implementing the method of the present invention, FIG. 2 is a block diagram showing the configuration of a control circuit of the device, and FIG.
The figures are similar to FIG. 1 and 4 according to a modified embodiment of the present invention.
The figure shows an example of processing a helical gear. In the drawing, 1 is the encoder, 4 is the hob head/hob saddle, 5 is the hob car 2, 6.13 is the drive motor, 7.14 is the speed/position detector, 8 is the workpiece, 9 is the table, 16 is the pulse quadrupled circuit. 17 is a binary rate multiplier (BRM); 18 is a pulse direction selection circuit. 18 is a table axis motor drive amplifier, and 20 is an arithmetic processing unit.

Claims (1)

[Claims] By controlling the rotation speed of the table axis in real time according to predetermined conditions based on data from a position detector installed in the drive motor of the axial axis of an NC hobbing machine equipped with an NC indexing axis and an axial axis. A method for controlling a table axis for an NC hobbing machine, characterized in that a synchronized relationship is maintained between a scheduled axial axis feed rate and a rotation speed of the table axis.