JPH10100042A - Tapping method for machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten whole tapping process time in a machine tool. SOLUTION: In a tapping method for a machine tool, a tap starts to be rotated while it is fed fast in the axial direction of tapping and is rotated at predetermined rotational speed. A fast feed speed is decreased and, when the feed speed reaches the feed speed which is synchronous with the predetermined rotational speed in a relation consistent with the lead of a screw, a tapping operation is started at the predetermined rotational speed and, in the middle of tapping operation, the rotational speed and the feed speed are synchronously decreased in a relation consistent with the lead of a screw and the tapping operation is completed. A reverse rotational speed and a return speed are synchronously increased in a relation consistent with the lead of a screw to perform a return process and, after the reverse rotational speed reaches the predetermined rotational speed, the return process is continued while both speeds are kept.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a tapping method for a machine tool.

[0002]

2. Description of the Related Art In general, tapping by a machine tool is performed by synchronizing rotation of a tap mounted on a spindle with feed between the spindle and a workpiece corresponding to the lead of the screw. In the tapping of a conventional machine tool, a spindle S equipped with a tap T is provided with a spindle rotation motor 6 and a spindle feed motor 8 controlled by the controller 1 based on a speed process indicated by a broken line in FIG. Adds feed and rotation.

[0003] 1. The rotation of the spindle S stopped at the standby position is stopped. 2. While the rotation is stopped, the spindle S is stopped (0).
It is fast-forwarded while speeding up. After a lapse of a predetermined time, T
After reaching the predetermined rapid traverse speed (F0) at one point,
The rapid traverse at the rapid traverse speed (F0) is continued, and the speed is reduced from the rapid traverse speed (F0) at T3.

[0004] 3. The spindle S during the rapid traverse speed deceleration becomes zero at time t4 when the tap T reaches the vicinity of the tapping start point of the workpiece W, that is, the feed of the spindle S is temporarily stopped (0), and immediately thereafter, the spindle S is stopped. Then, the tap vertical feed is started again while the speed is increased from the stop state (0). Simultaneously with the start of the feed of the spindle S (time t4), the rotational drive of the stopped spindle S is started, and the spindle S is rotated while increasing the speed from the stopped state (0). The feed speed and the rotation speed of the main shaft are synchronously increased in a relationship that matches the lead of the screw. Then, by tapping the tap, the tap T
Comes into contact with the workpiece W, and tapping is started.

[0005] 4. Then, at time t5 when tapping is performed to the intermediate point of the depth of the screw hole, the rotation speed during the speed increase reaches the maximum rotation speed possible for tapping or a lower speed (N '). After the feed speed during the speed increase reaches the feed speed (F ′) related to the screw speed with respect to the rotation speed (N ′), the rotation speed and the feed speed of the main shaft are immediately changed to the screw speed. The speed starts to be reduced from the predetermined rotation speed (N ') and the feed speed (F') while being synchronized with each other in a relationship matching the lead, and the tapping is continued.

[0006] 5. At time t6 when tapping is performed to the tapping end point at the bottom of the screw hole, the spindle S which is decelerating is
Both the feed speed and the rotation speed of the spindle S become zero, that is, the feed and rotation of the spindle S are temporarily stopped (0), and immediately thereafter, the feed speed and the rotation speed of the spindle S are in a relationship suitable for the screw lead. The reverse rotation and the return feed of the main shaft S are performed synchronously while the speed is increased from the stop state (0).

[0007] 6. At the time point t7 when the tip of the tap T returns to the middle point of the depth of the screw hole, the rotation speed of the spindle S, which is fed back while rotating in reverse, reaches the rotation speed (-N '), and the return speed is the same as the rotation speed (-N'). After reaching the feed speed (-F ') that matches the screw lead with respect to the rotation speed (-N'), the rotation speed and the return speed of the spindle S are synchronized in a relationship that matches the screw lead. At time t8 when the tap T returns to the return end point away from the screw hole, both become zero. That is, the return feed and the reverse rotation of the main spindle are stopped (0).

[0008] 7. Then, while the rotation is stopped, the spindle S is rapidly traversed while increasing the speed from the stop state (0). After a lapse of a predetermined time, after reaching a predetermined rapid return speed (-F0) at time t9, the rapid return at the rapid return speed (-F0) is continued, and at time t10, the return speed of the spindle S becomes the rapid return speed. The deceleration starts from (−F0), and at time t11
It becomes zero at. That is, the spindle S is in the stopped state (0) at the standby position.

[0009]

Originally, in a tapping operation in which the feed speed between the tap and the workpiece and the rotation speed of the spindle were synchronized with each other in accordance with the lead of the screw, the tap and the workpiece came close to each other. At the tapping feed start point, the feed speed between the tap and the workpiece and the rotation speed of the spindle are each increased from the stopped state to the maximum possible speed for tapping, and tapping is continued at the maximum speed. After that, the feed speed between the tap and the workpiece and the rotation speed of the spindle are reduced from the maximum speed, and at the tapping end point where tapping is performed to the bottom of the screw hole, the respective speeds become zero. Can be considered.

However, since the depth of the screw hole is usually not as deep as the left, at the tapping end point where tapping is performed to the bottom of the screw hole, it is necessary to use a tap to make each speed zero. Since the feed speed to the workpiece and the rotation speed of the spindle are increased to the maximum speed at which tapping is possible and there is no room for continuing tapping at the maximum speed, the above-described conventional technique shown in FIG. Like the tapping in machine tools of
The feed rate between the tap and the workpiece and the rotational speed of the spindle must each be reduced immediately before or even if the tapping speed is increased to the maximum possible speed. The processing efficiency is poor in such a speed process. Therefore, if a drive device with high acceleration / deceleration performance is used, the problem is reduced, but it causes a high cost,
Further, there is a limit to the improvement of the acceleration / deceleration performance of the driving device.

[0011]

In the tapping method for a machine tool according to the present invention, the tapping is started in a rapid traversing process in the axial direction of the tapping, and the tapping is performed at a predetermined rotational speed, while the tapping speed is reduced. The tapping is started at the feed speed when the feed speed is synchronized with the predetermined rotational speed in a relationship suitable for the lead of the screw and the predetermined rotational speed. , Synchronously decelerates in the relationship that matches the screw lead, finishes tapping, performs the return stroke while increasing the reverse rotation speed and the return speed in synchronization with the relationship that matches the screw lead, When the reverse rotation speed reaches the predetermined rotation speed, the two speeds are returned as they are, and the process is continued.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A control device for a machine tool for performing tapping according to an embodiment of the present invention will be described with reference to FIG. The control device 1 includes a CPU 2, a memory 3 in which control data is stored and connected so that the control data is input / output to / from the CPU 2, and interfaces 4 and 5 for connecting input / output of commands and data between the CPU 2 and the outside. It is composed of

A drive unit 7 for controlling the drive of a spindle rotating motor 6 of a machine tool, a drive unit 9 for controlling a drive of a spindle feed motor 8, an encoder 10 for detecting the rotation speed of the spindle rotary motor 6, and a spindle feed The encoder 11 for detecting the number of revolutions of the motor 8 is connected to the interface 4, and the spindle rotation motor 6 and the spindle feed motor 8
Driven based on a command from the CPU 2, the rotation speeds of the spindle rotation motor 6 and the spindle feed motor 8 are controlled by the CPU 2.
To be entered. Appropriate external input devices 12 and output devices 13 are connected to the CPU 2 via the interface 5 so that data and instructions are input to and output from the CPU 2.
2 are connected.

The spindle rotation motor 6 and the spindle feed motor 8 are individually driven to rotate with their rotation speed and feed speed controlled based on commands from the CPU 2 of the control device 1. That is, the tap T mounted on the main shaft S rotates at a rotational speed controlled by the control device 1 with respect to the workpiece W and moves forward and backward at a controlled feed speed. The rotation speed, the rotation direction and the rotation amount of the main shaft S and the feed speed / the feed direction and the feed amount are detected by the encoder 10 and the encoder 11, and the detection signal is transmitted to the C through the interface 4.
It is input to PU2, and the feed and rotation of the following spindle S are controlled based on it. In the above explanation, the feed is on the spindle side,
That is, although the processing is performed on the tap side, the processing may be performed on the table side, that is, on the workpiece side.

In the tapping operation, the spindle S having the tap T mounted thereon is rotated by the spindle rotating motor 6 controlled by the controller 1 based on the speed process shown by the solid line in FIG.
Feeding and rotation are added by the spindle feed motor 8. 1. The rotation of the spindle S stopped at the standby position is stopped.

2. With the rotation stopped, the spindle S is rapidly traversed from the stopped state (0) while increasing the speed. After a lapse of a predetermined time, after reaching a predetermined rapid traverse speed (F0) at time T1, rapid traverse at the rapid traverse speed (F0) is continued,
At time T3, the speed is reduced from the rapid traverse speed (F0).

3. At time T2 during rapid traverse of the main spindle S at the rapid traverse speed (F0), the rotational driving of the main spindle S is started, and the main spindle S is rotated while increasing the speed from the stop state (0). After a lapse of a predetermined time, the tapping reaches the maximum possible rotation speed (N) at time T4, and then the rotation at the maximum rotation speed (N) is continued.

4. The spindle S during the rapid traverse speed deceleration reaches a feed speed (F) that matches the screw lead with respect to the maximum rotation speed (N) of the spindle S at a time T5 before tapping is started. At that time T5, since the spindle S is already rotating at the maximum rotation speed (N), the maximum rotation speed (N) synchronized with the lead of the screw and the feed speed (F) are obtained. . Then, the feed of the spindle S is decelerated and stopped, the spindle S is maintained at the feed speed (F), and the tapping feed is started, and the tap T approaches the workpiece W.
Then, tapping is started when the tap T comes into contact with the workpiece W. The lead L of the screw hole is F / N.

5. The tap T which is in contact with the workpiece W taps the workpiece at the rotation speed (N) and the feed speed (F) which are synchronized in relation to the lead of the screw, and the depth of the screw hole At the time T6 when the tapping is performed up to the intermediate point, the rotation speed and the feed speed of the spindle S are synchronized with the predetermined rotation speed (N) and the feed speed (F) in synchronization with the lead of the screw. Then, deceleration starts, and tapping continues.

6. At the time T7 when tapping is performed to the tapping end point at the bottom of the screw hole, the spindle S that is decelerating is
Both the feed speed and the rotation speed of the spindle S become zero, that is, the feed and rotation of the spindle S are temporarily stopped (0), and immediately thereafter, the feed speed and the rotation speed of the spindle S are in a relationship suitable for the screw lead. The reverse rotation and the return feed of the main shaft S are performed synchronously while the speed is increased from the stop state (0).

7. At the time T8 when the tip of the tap T returns to the middle point of the depth of the screw hole, the reverse rotation speed of the spindle S, which is fed back while rotating in reverse, is the maximum rotation speed (-
N), and the return speed reaches a feed speed (-F) that matches the screw lead relative to the maximum rotational speed (-N).

8. Then, the main spindle S has a return speed (−
F), the return feed is continued at the reverse rotation speed (-N), and at time T9 when the tap T returns to the return end point which is a position away from the screw hole, the spindle S rotates at the reverse rotation speed (-N). )) And the return starts increasing from the return speed (-F). After a lapse of a predetermined time, at time T10,
The main spindle S reaches the fast-return speed (-F0), and thereafter, fast-return is performed at that speed. During this time, the decelerated reverse rotation speed of the spindle S becomes zero at time T11. That is,
The reverse rotation of the main shaft S is stopped (0). After the point T8 at which the tip of the tap T returns to the intermediate point of the depth of the screw hole, the spindle S is further increased in synchronism with the return speed (-F) and the reverse rotation speed (-N) while maintaining the synchronous relationship. It may return to the return end point. Subsequent deceleration from the reverse rotation speed and return from the fast return speed are the same as described above. Thereby, the return time of the spindle S is further reduced.

9. After a lapse of a predetermined time from time T10, at time T12, the return speed of the spindle S becomes the rapid return speed (-F0).
, And becomes zero at time T13. That is,
The spindle S is in the stopped state (0) at the standby position.

When the tapping speed process in the above embodiment is compared with the tapping speed process in the above-described conventional technique, the acceleration performance of the driving motor is high, and the tapping start point to the intermediate point of the screw hole is high. Can be accelerated from the rotation stop state to the maximum rotation speed at which tapping can be performed during the feeding of the motor, and it is assumed that N = N ′, and even if the acceleration and deceleration of the rotation motor and the feed motor in both are the same, Δ = It is reduced by Δ1 + Δ2 + Δ3.

Δ1: From the point when the rapid traverse speed during deceleration in the conventional rapid traverse process becomes the feed speed F which is in relation to the tapped maximum rotational speed N and matches the lead of the screw, the feed speed becomes zero (stop state). ), And after the feed and rotation of the tap are started while being accelerated while maintaining the relationship suitable for the lead of the screw, the time from when the tapping is started until the tap reaches the middle point of the screw hole and From the point in time when the rapid traverse speed during the deceleration in the rapid traverse process of the present invention becomes a feed speed F that is in relation to the tapped maximum rotational speed N in accordance with the lead of the screw, the feed at the feed speed F is continued. The difference from the time when the stand is started and the tap reaches the middle point of the screw hole

Δ2: From the point in time when the tap in the return stroke of the prior art reaches the intermediate point of the screw hole, the feed and rotation maintain the relation that matches the screw lead, and the tap is separated from the screw hole and stopped while being decelerated. From the time until the return end point is reached, and from the time when the intermediate point of the screw hole in the rapid traverse process of the present invention is reached, the tap is held at the rotation speed at that time with the return speed that is in accordance with the screw lead. Difference from time required to reach return end point away from screw hole Δ3: Fast return starts while increasing speed from the point of time (stop state) at which the return end point in the conventional return stroke is reached, and fast return speed− From the time until reaching the point F0, and from the point when the return end point in the return stroke of the present invention is reached (early return speed -F), the fast return is started while increasing the speed, and from the point when the fast return speed -F0 is reached. The difference between the time of

As shown in FIG. 3, assuming that the acceleration / deceleration is a constant value, for Δ1 and Δ2, the fast-forward speed during deceleration is the feed speed in relation to the tapped maximum rotational speed N that matches the screw lead. The time from the point when it becomes F to the point when the tap reaches the middle point of the screw hole, and the time from the point when the tap reaches the middle point of the screw hole until the tap reaches the return end point where the tap separates from the screw hole in the return stroke. Are reduced to １ ／ each in the above-described embodiment as compared with the prior art.

As for Δ3, rapid return is started while increasing the speed from the point when the return end point is reached, and the time until the point when the rapid return speed −F0 is reached is represented by α, where the acceleration of the rapid return stroke is α. In the case of the above embodiment, the time is shortened by F / α as compared with the case of the related art.

[0029]

According to the tapping method for a machine tool of the present invention, the spindle, that is, the tap, is rotated to a predetermined tapping rotation speed before the tap approaches the workpiece at the deceleration rapid traverse and the tapping is performed. When the rotating speed reaches a feed speed that is in accordance with the rotational speed and the lead of the screw, the feed speed and the rotational speed are synchronized, a tapping feed is performed, and tapping is performed as it is. In the return stroke, the two speeds return to the return end point without deceleration due to the reverse rotation speed and the return speed of the main shaft synchronized with the reverse rotation speed in accordance with the lead of the screw.

Therefore, as in the prior art, when the tapping is started, the rotation of the spindle is reduced to a state where the rotation and the feed of the spindle are stopped, and the rotation and the feed of the spindle are stopped from the state where the tapping is started. The tapping is performed while increasing the speed, and in the return step, when returning to the tapping intermediate area, the reverse rotation speed that has reached the predetermined tapping rotation speed and the return speed of the main shaft are reduced, and the return is completed. The overall process time is reduced as compared to a speed process that is stopped at a point. Furthermore, since the rotation speed of the spindle is at the predetermined speed at the start of tapping, tapping can be performed efficiently even if the screw hole is not deep and the acceleration / deceleration performance of the driving device is not high. .

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a control device of a machine tool that performs a tapping method according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a tap mounted on a spindle of a machine tool and a screw hole of a workpiece in a tapping method.

FIG. 3 is a graph showing a relationship between a rotational speed and a feed speed of a spindle of a tapped machine tool according to an embodiment of the present invention and a conventional technique.

[Description of Signs] 1 Controller 2 CPU 3 Memory 4,5 Interface 6 Spindle rotation motor 7,9 Drive 8 Spindle feed motor 10,11 Encoder 12 Input device 13 Output device S Spindle T Tap W Workpiece

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideki Sato 1-1-1, Asahi-cho, Kariya-shi, Aichi Toyota Machine Works Co., Ltd. (72) Inventor Tetsuo Teramura 1-1-1, Asahi-cho, Kariya-shi, Aichi Toyoda Machine Inside the corporation

Claims (3)

[Claims] 1. In a tapping fast-forward process in the axial direction, rotation of a tap is started and rotation is performed at a predetermined rotation speed, while the rapid-feed speed is reduced, and the tapping speed is reduced to a value suitable for the screw lead. A tapping method for a machine tool that performs tapping while maintaining a synchronous relationship between a feed speed when a synchronized feed speed is reached and the predetermined rotation speed. 2. In the return stroke in the axial direction of the tapping, the rotational speed of reverse rotation and the return speed of return feed are synchronized in accordance with the relationship of the lead of the screw, and the synchronous relationship is maintained without decelerating both speeds. Tapping method in a machine tool that performs a return stroke. 3. In the tapping axis fast-forward process, rotation of the tap is started, rotation is performed at a predetermined rotation speed, and while the tapping speed is reduced, the tapping speed is reduced to a value suitable for the screw lead. Start tapping at the feed speed and the predetermined rotation speed when the synchronized feed speed is reached,
In the middle of tapping, the rotation speed and the feed speed are synchronously reduced in a relationship that matches the screw lead, and the tapping is completed. The reverse rotation speed and the return speed are synchronized in a relationship that matches the screw lead. A tapping method for a machine tool that performs a return stroke while increasing the speed and then returns to the predetermined rotation speed while maintaining the two speeds and continues the stroke.