JPS63200913A - Automatic tapping device - Google Patents

Abstract

PURPOSE:To contrive adaptive control of a tap by providing with a means to calculate a rotation stop position for setting a rotation stop position of a main shaft just before the position of the bottom of a hole and a means to apply an acceleration/reduction time constant to let the action of a feed control means correspond with the action of a main shaft driving means. CONSTITUTION:A rotation stop position calculating means 9 preliminarily sets a stop position of a main shaft just before the position of the bottom of a hole, and if an arrival position detecting means 11 detects arrival of a tap, a main shaft driving means 6 starts reduction. In the mean time, an acceleration/ reduction time constant applying means 10 applies a predetermined time constant to a feed control means 8 so as to smooth reduction in Z-axis and stop the tap at the position of the bottom of a hole. For returning, the arrival position detecting means 11 commands feed for reversing and returning the main shaft, and the acceleration/reduction time constant applying means 10 applies a time constant to the feed control means to smooth acceleration in Z-axis, so that rotation of the main shaft and return in Z-axis correspond with each other. Thus high grade tapping is made possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an automatic thread processing device for a machine tool,
In particular, it relates to an automatic threading machine with adaptive control of taps.

[Conventional technology]

Conventionally, as shown in FIG. 5, a threading device for a machine tool holds a tap tool T on a main shaft H, and drills a threaded hole in a workpiece W while rotating the tap by the main shaft. In addition to numerically controlling the rotation speed of the spindle, the initial point I and the approach point R2 are set at the bottom position Wzo in coordinates with the spindle direction as the Z axis, and the feed rate during this period is normally from the initial point ■ to the approach point R. is approached at a rapid traverse speed F1, and from the approach point R to the hole bottom position z
Numerical control is performed so that machining is performed at cutting speed F2 up to 0, and when machining is completed, the spindle is reversed while returning from hole bottom position Z0 to approach point R at cutting speed F2, and then returned to initial point I at rapid traverse speed F1. It was common to do so.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional apparatus, due to the inertia delay in mechanical operation and the delay in electrical control, the rotation stop of the main shaft does not coincide with the stop of the feed, resulting in the following problems.

In other words, even if the machine stops the feeding operation at the hole bottom position Z0, the main shaft continues to rotate due to the inertia of the rotational moment, and the thread cutting progresses until the hole is drilled to the position shown as point Ze in Figure 5. That's true.

Another reason is that an elongating or contracting force acts on the tap.The reason for this is that there is a difference in the start timing of the spindle drive operation and the feed operation, or there is a difference in the acceleration/deceleration time constants. Since the spring B is interposed in the attachment part of the tool T, there will be no mechanical damage, but the machining result will be subject to errors.

FIG. 4 is a graph comparing the relationship between the drive operation and the feed operation of the main shaft, with the horizontal axis showing time and the vertical axis showing the rotational speed and feed speed of the main shaft. In Fig. 4, if a command is given to stop rotation and feed at time t0, the Z-axis is driven by a servo motor, and the inertia at the cutting feed rate is slight, and it stops at time t1, but the main shaft rotation In the case of , first, the speed starts to decelerate at time t2 due to the delay time T1 of the control signal,
Furthermore, since the deceleration time constant of the main shaft is large, the mechanical operation finally stops at time t3 due to delay time T2. Normally, the return operation should immediately shift to reverse operation, but due to the delay time T3 of the control signal, the reverse operation finally begins at time t4, and the Z-axis is driven only when the reverse signal is sent and received by the operation side, and the Z-axis is driven correctly. It will be sent back at time t5.

A region L1 indicated by diagonal lines in the figure shows the expansion of the tap, and a region L2 shows the contraction of the tap.

This elongation of the tap disturbs the position of the bottom of the hole, resulting in interference with the bottom insert, and shrinkage of the tap may damage the outlet of the hole.

In particular, since small-diameter taps made of aluminum or the like have a high spindle rotation speed, the above-mentioned tendency is even stronger, and machining that requires precision becomes even more difficult. For example, countermeasures include synchronizing the drive of the main shaft using servo motors, but this requires a special NC device and is often extremely expensive.

The present invention was devised in view of these problems, and it combines the slow control pattern with the fast control pattern to reduce delays in machine operation and control during tapping, and uses relatively simple and inexpensive hardware. The purpose of the present invention is to provide an automatic threading machine capable of high-quality tapping.

[Means for solving problems]

In the present invention, the measures taken to solve the above problems include a spindle drive means that instructs the rotation speed of the spindle using an NC machining program, and a spindle drive means that controls the tap hole bottom position and the feed rate of the spindle using an NG machining program. The automatic threading machine is equipped with a feed control means that calculates a delay in rotational operation in advance and sets a rotation stop position of the main spindle before the hole bottom position, and a feed control means. The present invention is an automatic threading device that adaptively controls taps, and includes acceleration/deceleration time constant adding means for making the operation substantially coincide with the operation of the spindle drive means.

[Effect]

In the present invention, as a countermeasure for the deviation of the hole bottom position that occurs when the spindle driving means instructs the rotational speed of the spindle, the rotation stop position calculation means calculates the delay in the rotational operation in advance, Set the spindle rotation stop position. Furthermore, when the feed rate is instructed by the feed control means, execution is much faster than that of the spindle drive means, so the acceleration/deceleration time constant adding means adds a time constant to the operation of the feed control means, Almost match the action. By adjusting the timing and operation in advance in this manner, the present invention performs adaptive tap control.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the basic configuration of an automatic threading machine embodying the present invention. In FIG. 1, the automatic cutting machine includes a CPU 1, a display 2 with a keyboard, an input/output board 2a thereof, an NC processing program memory 3 for storing an NG processing program, and initial points and approach points from the NC processing program. and a coordinate value setting memory 4 for extracting and temporarily storing the coordinate values of the hole bottom position, a spindle driving means 6 for instructing the rotational speed of the spindle motor 5 according to the NC machining program, and a coordinate value setting memory 4 for extracting and temporarily storing the coordinate values of the hole bottom position; The feed control means 8 instructs the feed speed of the spindle, the rotation stop position calculation means 9 sets the spindle rotation stop position before the hole bottom position, and the operation of the feed control means 8 is almost the same as the operation of the spindle drive means 6. It is comprised of an acceleration/deceleration time constant adding means 10 for matching, and an arrival position detection means 11 for detecting the tap arrival position. A tachometer generator 5a is attached to the main shaft motor 5, and a pulse generator 7a is attached to the Z-axis motor 7, which feeds back the respective rotational speeds to the main shaft drive means 6 and the feed control means 8.

The rotation stop position calculation means 9 sets the rotation stop position of the spindle before the hole bottom position by applying the deceleration time of the spindle rotation speed to the cutting feed rate in advance, and the reached position detection means 11 causes the tap to reach the rotation stop position. When it is detected that the acceleration/deceleration time constant has been reached, the main shaft driving means 6 starts decelerating, while
0 gives a predetermined time constant to the feed control means 8 to slow the deceleration of the Z axis, starts decelerating the feed from the rotation stop position, and simultaneously stops the spindle rotation at the desired hole bottom position and taps. Make it stop. In the case of a return operation, when the reaching position detection means 11 detects that the tap has reached the hole bottom position, a command is given to reverse the spindle and feed in the return direction at the same time, and the feed control means 8 is given an acceleration/deceleration time constant adding means. 10 provides a predetermined time constant, thereby slowing down the acceleration of the Z axis and harmonizing the rotation of the main shaft and the return of the Z axis.

FIG. 2 is a circuit diagram specifically showing an example of signal processing with the above configuration. In the same figure, an initial point coordinate value memory 4a, an approach point coordinate value memory 4b, and a Taisei position coordinate value memo IJ4C are each memory in the coordinate value setting memory 4 in FIG. The detection circuits 11a, llb, and llc form the reached position detection means 11 in FIG. Further, the calculation result of the rotation stop position calculation means 9 is stored in the rotation stop position coordinate value memo IJ.
9a, and is input to the minus number output circuit 9b.

These -number configuration circuits 11a, flb, llc and 9b
The Z-axis current position coordinate value data is inputted from the feed control means 8, and when it matches the data from each coordinate value memory, an initial point arrival signal is generated.

An approach point arrival signal, a hole bottom position arrival signal, or a rotation stop position arrival signal is issued, respectively. The subsequent signal processing differs depending on whether the operation is performed after the tap has already reached the hole bottom position, so please refer to the hole bottom position arrival memo + J 11, which will be described later.
d is registered, and the registration result is each AND gate 12a, 12b.

12c, 12d, 12e, 12g, etc. as a confirmation signal. First, the initial point arrival signal is confirmed by the angle controller 12a to be before reaching the hole bottom position, and then is commanded to the feed control means 8 as a rapid forward advance signal. The approach point arrival signal is distinguished by the AND gate 12b or 12C before and after reaching the hole bottom position, and before reaching the hole bottom position, the AND gate 12b commands the feed control means 8 as a cutting feed advance signal, and after reaching the hole bottom position, the AND gate 12C sends a command to the feed control means 8 as a fast forward return signal. Further, after this approach point arrival signal is confirmed by the controller 12e to be before reaching the hole bottom position, it is commanded to the main shaft driving means 6 as a normal rotation signal of the main shaft. The hole bottom position arrival signal is AND gate 12
After confirming at step d that the hole bottom position has not yet been reached and that the spindle rotational speed has reached zero, a command is sent to the feed control means 8 as a cutting feed return signal. The fact that this cutting feed-back signal is commanded means that the hole bottom position has been reached, so it is taken out and sent to the hole bottom position arrival memory 11d.
The arrival or non-arrival will be registered. This cutting feed back signal is also input to the AND gate 12g,
The operational amplifier 12h matches the signal indicating the reverse state of the main shaft.
If it is not obtained within the set time, the main shaft drive means 6
and the feed control means 8. After confirming that the rotation stop position arrival signal has not yet reached the hole bottom position at the angle controller 12f, it is commanded to the spindle drive means 6 as a spindle stop reverse rotation signal.

The spindle rotation speed is taken out from the spindle drive means 6, and the zero coincidence detection circuit 6a and the minus number configuration circuit 6b detect that it has reached zero and that it has reversed to the minus side, and the spindle rotation zero signal is It is used to confirm that the hole bottom position has been reached, and the main shaft reversal signal is used to determine the alarm.

FIG. 3 is a graph comparing the relationship between the drive operation and the feed operation of the main spindle in the present invention, with the horizontal axis showing time and the vertical axis showing the rotation speed and feed speed of the main spindle. In FIG. 3, time ts is the time when the rotation stop position arrival signal is issued, and the rotation and feeding operations are decelerated according to the acceleration/deceleration time constant and stopped at time t0. When the arrival at the hole bottom position and zero rotation of the spindle are confirmed, a cutting feed-back command is issued, and the spindle starts rotating in reverse at time tb after a control delay time has elapsed. The cutting send-back command causes the operational amplifier 12h' to start the return operation in time with time tb. The rotation and feed operations are accelerated in harmony according to the acceleration/deceleration time constant, and return to normal rotation speed and feed speed at time tg.

By applying the acceleration/deceleration time constant of the present invention not only to the feed control side but also to the spindle drive side, and by matching both acceleration/deceleration time constants, the rotation of the spindle and the return of the Z-axis can be more perfectly harmonized. can be done.

〔Effect of the invention〕

As explained above, according to the present invention, an automatic thread processing device that automatically detects and adaptively controls delays in machine operation and control during tapping, and is capable of high-quality tapping with relatively simple and inexpensive hardware. can be provided.

[Brief Description of the Drawings] Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is a circuit diagram of an example of signal processing of the embodiment, Fig. 3 is an explanatory diagram of timing of the embodiment, and Fig. 4 is a diagram illustrating the timing of the embodiment. The figure is an explanatory diagram of the timing of the conventional example.
The figure is an explanatory diagram of thread cutting. 1; CPU. 3; NC machining program memory; 6; spindle drive means; 8; feed control means; 9; rotation stop position calculation means; 10; acceleration/deceleration time constant addition means. Patent applicant Hitachi Seiki Co., Ltd. Figure 2, Figure 3, s Figure 4

Claims (1)

[Claims] In an automatic screw machining device, which is equipped with a spindle drive means that instructs the rotational speed of the spindle according to an NC machining program, and a feed control means that instructs the bottom position of the tap hole and the feed speed of the spindle according to the NC machining program, rotational operation is performed in advance. rotation stop position calculation means for calculating the delay of the spindle and setting the rotation stop position of the spindle before the hole bottom position; and acceleration/deceleration time constant adding means for making the operation of the feed control means substantially coincide with the operation of the spindle drive means. An automatic thread processing device characterized in that it is equipped with a tap and performs adaptive control of a tap.