JPH1086018A - Screw cutting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately position the forward-most position of a screw cutting shaft by providing a thread structure part which is formed at the same pitch as a pitch of a cutting tool and a screw cutting shaft forward/retreat means which forwards/retreats the screw cutting shaft rotated by rotation of a drive motor by a prescribed quantity. SOLUTION: A male screw 39 is worked in a tap shaft 27 at a part matching with a screw bush 35 and a female screw 41 for threadly engaged with the male screw 39 is worked in the screw bush 35 side. The thread structure between the tap shaft 27 and the screw bush 35 is set to a prescribed pitch so that the feed stroke of the tap shaft 27 is accurately set by controlling the rotation speed of a tap shaft rotation control servo motor. The prescribed pitch is the same pitch as the pitch of the cutting tap.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread cutting device, and more particularly to a thread cutting device (e.g., a female tapping process using a tap, which does not require a complicated structure and does not increase the cost). Alternatively, the present invention relates to a device devised so as to be able to perform external thread processing using a die.

[0002]

2. Description of the Related Art For example, in the processing of minute precision parts, it may be necessary to perform thread cutting to a position very close to the bottom of a pilot hole formed in the part. However, when the tapping shaft is rotated by a driving motor or the like to perform thread cutting, even if the driving motor is stopped at a predetermined timing, the tapping shaft may not stop accurately at a predetermined position and may go too far. is there. This is because inertia due to the inertia moment of the tap shaft acts. or,
By fixing the tap axis and rotating the work,
In some cases, thread cutting is performed. In such a case, there is inertia in the rotary drive system that rotates the work, and similarly, the tap shaft may overshoot the predetermined stop position. As described above, when the tap shaft has gone too far, the most advanced position of the tap shaft collides with the bottom of the pilot hole, and the tap shaft may be damaged. In response to this, it is conceivable to stop the drive system before the predetermined stop position in consideration of such inertia. However, in this case, since the amount of overshoot due to inertia is not constant, the tap shaft may stop at a position far away from the bottom of the pilot hole. In such a case, the depth of the machined screw hole becomes largely insufficient, and there is a possibility that a desired function cannot be obtained. Thus, it has been extremely difficult to accurately position the most advanced position of the tap shaft with respect to the work.
There is also a configuration in which the rotation of the tap shaft is rotated forward and reverse using a cam, but in such a case,
The timing may be shifted, and it is difficult to accurately position the most advanced position of the tap shaft with respect to the work.

Therefore, in the conventional case, in order to accurately position the most advanced position of the tap shaft with respect to the workpiece, the rotation of the thread cutting shaft and the feed control of the axis for feeding the thread cutting shaft (so-called Z axis) are performed. It was performed by simultaneous control of two axes. Also, for example, in the case of performing a threading process that is oblique with respect to the axis of the work on an automatic combined machining lathe, the rotation control of the threading shaft and the installation of the threading shaft are performed, and two parallel and orthogonal to the main shaft are provided. This is performed by simultaneously controlling three axes of a so-called XB axis and a ZB axis between the tool table and the tool table which is driven and controlled in the direction.

[0004]

According to the above-mentioned conventional configuration, there are the following problems. As described above, in the conventional case, in order to accurately position the most advanced position of the tap shaft with respect to the workpiece, in the former case of the conventional example, the rotation control of the tap shaft and the feed shaft of the tap shaft (so-called Z axis) are performed. It is necessary to perform machining by simultaneous control of two axes during feed control of the (axis), or in the case of the latter in the conventional example, to control the rotation of the tap axis and to feed the tap axis in two orthogonal directions. It is necessary to control the three axes of the so-called XB axis and ZB axis at the same time, which complicates the configuration of the apparatus and increases the cost.

The present invention has been made on the basis of the above points, and an object of the present invention is to make the most of a thread cutting shaft for a work without complicating the structure of the apparatus and making it expensive. It is an object of the present invention to provide a threading device capable of accurately positioning an advanced position.

[0006]

In order to achieve the above object, a thread cutting apparatus according to a first aspect of the present invention comprises a drive motor capable of controlling rotation, a threaded shaft rotated by rotation of the drive motor, and a threaded shaft. A cutting tool attached to the tip of the workpiece and having an arbitrary pitch to perform thread cutting on the workpiece; and a screwing structure provided on the threading shaft and configured at the same pitch as the pitch of the cutting tool. And a threading shaft advance / retreat means for advancing / retreating a threading shaft rotated by rotation by a predetermined amount. According to a second aspect of the present invention, there is provided the threading device according to the first aspect, wherein the screwing structure portion is attached to and detached from a male thread portion formed on the threading shaft while rotation is regulated by the outer periphery of the threading shaft. And a female thread portion formed on the screw bush so as to be capable of being arranged. When the pitch is changed, the threaded shaft and the screw bush are exchanged. A third aspect of the present invention is the threading apparatus according to the first aspect, wherein the cutting tool is a tap for cutting, and a center drill and a pilot hole drill are provided together to form a unit. It is assumed that. The threading device according to the fourth aspect is the threading device according to the third aspect,
The entire unit can be inclined at a predetermined angle with respect to the work.

That is, in the case of the present invention, by rotating the servo motor by a predetermined amount, the amount of advance of the threading shaft and thus the cutting tool is automatically defined by the threading shaft advance / retreat means. Therefore, for example, when a female tap is machined in a prepared hole of a work using a cutting tap as a cutting tool, the distance from the bottom of the prepared hole of the work to the cutting tap is determined by the pitch (screw) of the cutting tap. (Same as the pitch of the integrated structure), thereby determining the rotation amount of the drive motor. Thereafter, if the drive motor is controlled to rotate by the rotation amount, the cutting tap can be accurately advanced to a predetermined position of the prepared hole of the work. That is, it is possible to accurately execute a predetermined amount of thread cutting. The same applies to the case where a cutting die is used as a cutting tool and a male screw is machined on a work. Further, in the case where the screwing structure portion is composed of a male thread portion formed on the threading shaft and a female thread portion formed on a screw bush removably arranged in a state where rotation is restricted on the outer periphery of the threading shaft. By changing the threaded shaft and the threaded bush, the pitch can be easily changed. In addition, when a tap for cutting is used as a cutting tool, a center drill and a pilot hole drill are installed side-by-side. Drilling of a pilot hole and thread cutting by a cutting tap can be performed. At that time,
If the entire unit can be tilted at a predetermined angle with respect to the workpiece, set the tilt angle of the unit according to the tilt of the thread cutting surface of the workpiece, and then control only the rotation axis of the tap shaft Just by doing so, a desired thread cutting process can be performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
A first embodiment of the present invention will be described. This embodiment shows an example in which the workpiece 3 is threaded by the threading device 5 while the workpiece 3 is held by the workpiece holding means 1. It is assumed that the workpiece 3 is pre-drilled, and that the prepared hole is subjected to internal thread processing by the threading device 5.

Hereinafter, the configuration of the threading device 5 will be described. First, there is a base 7, on which a tap shaft unit 9 is attached. The tap shaft unit 9 has the following configuration. First, there is a tap shaft rotation control servomotor 11 as a drive motor, and this tap shaft rotation control servomotor 11 includes:
An encoder 13 is attached. The output side of the tap shaft rotation control servomotor 11 is connected to a reduction gear head 15. The output shaft 15 a of the reduction gear head 15 is connected to a ball spline outer cylinder via a key 17 and a key groove (not shown). The holder 19 is connected. Therefore, the tap shaft rotation control servomotor 11
Is rotated, via the reduction gear head 15,
The ball spline outer cylinder holder 19 rotates.

A ball spline shaft 21 is disposed on the inner peripheral side of the ball spline outer cylinder holder 19.
The ball spline shaft 21 is connected to the
The rotation is transmitted from the ball spline outer cylinder holder 19 side. The coupling 2 is attached to the ball spline shaft 21.
A tap shaft 27 serving as a threading shaft is connected via 5. That is, the end of the ball spline shaft 21 and the end of the tap shaft 27 are inserted into the coupling 25,
The set screws 29 and 31 are screwed into them to connect and fix them. The tap shaft 27 is supported by a screw bush 35 and a bearing 37 provided in a support cylinder 33 fixed to the base 7.

As shown in FIG. 2, a male screw 39 is formed on a portion of the tap shaft 27 corresponding to the screw bush 35, while a male screw 39 is formed on the screw bush 35 side. Is machined. In the screw structure of the tap shaft 27 and the screw bush 35, the pitch is set at a predetermined pitch.
The feed amount of the tap shaft 27 can be accurately set by controlling the number of revolutions of the tap shaft rotation control servomotor 11 described above. The predetermined pitch is the same pitch as a pitch of a cutting tap described later. When the pitch is changed, the tap shaft 27 and the screw bush 35 may be replaced with another one. The screw bush 35 can be replaced by removing a plurality of screws 43 screwed into the flange 35a of the screw bush 35.

As shown in FIG. 1, a collet chuck mechanism 45 is attached to the tip of the tap shaft 27, and a cutting tap 47 as a cutting tool is detachably attached to the collet chuck mechanism 45. Have been.
The collet chuck mechanism 45 includes a sleeve 45a,
Collet chuck 45 arranged in the sleeve 45a
b and a fixing nut 45c screwed onto the outer periphery of the sleeve 45a. As already explained,
The pitch of the cutting tap 47 is the same as the pitch of the screwing structure.

A detection plate 49 is attached to the coupling 25 with its rotation restricted. That is, the detection plate 49 is rotatably attached to the coupling 25 via the bearing 51. The rotation of the detection plate 49 is regulated by the guide shaft 53. Therefore, even if the coupling 25 rotates, the detection plate 49 does not rotate, and
The ball spline shaft 21, the coupling 25, and the tap shaft 27 move forward and backward. Also provided are an origin setting switch 55 for setting the origin of the servomotor 11 for controlling the rotation of the tap shaft, an overtravel detection switch 57 for the forward movement of the tap shaft, and an overtravel detection switch 59 for the backward movement of the tap shaft.

The operation will be described based on the above configuration. First, the setting of the origin position of the tap shaft 27 will be described with reference to FIG. By pressing an origin return button on an operation panel (not shown), the following operation is performed, and the origin of the tap shaft 27 in the feed direction is set. This is the case where the tap shaft forward side overtravel detection switch 57 is on, or the tap shaft 27 has advanced from the origin position, and the origin setting switch 55 is off. As shown in the diagram, the tap shaft control servomotor 11 is driven to move the tap shaft 27 backward. Then, after the origin setting switch 55 is turned on, the tap axis control servomotor 11 is decelerated. After the origin setting switch 55 is turned off, the position where the Z-phase signal is turned on is set as the origin.

Next, there is a case where the tap shaft 27 is advanced from the origin position and the origin setting switch 55 is turned on. As shown in the fourth diagram in FIG. By driving the servo motor 11, the tap shaft 27
To move forward. Then, after the origin setting switch 55 is turned off, the tap shaft control servomotor 11 is rotated in the reverse direction to move the tap shaft 27 backward. Origin setting switch 55
Is turned on, the tap axis control servomotor 11 is decelerated. Then, the position where the first Z-phase signal is turned on after the origin setting switch 55 is turned off is set as the origin.

Next, the case where the tap shaft 27 is at a position retracted from the origin position and the origin setting switch 55 is turned off will be described with reference to the fifth diagram in FIG. Note that the same operation is performed when the tap shaft 27 is located at the origin position (in such a case, the state is normal). First, the tap shaft control servomotor 11 is driven to move the tap shaft 27 backward. Then, after the tap-axis retreat-side overtravel detection switch 55 is turned on, the tap-axis control servomotor 11 is rotated in the reverse direction.
The tap shaft 27 is advanced. And origin setting switch 5
After the switch 5 is turned on and further turned off, the tap shaft control servomotor 11 is rotated in the reverse direction to move the tap shaft 27 backward.
Then, after the origin setting switch 55 is turned on, the tap axis control servomotor 11 is decelerated, and after the origin setting switch 55 is turned off, the position where the first Z-phase signal is turned on is set as the origin. When the tap shaft 27 is retracted from the origin position and the tap-axis retreat-side overtravel detection switch 59 is turned on, the tap-axis control servomotor 11 is driven in the direction in which the tap shaft 27 moves forward.
The control after driving is the same as the control described based on the fifth diagram in FIG.

Next, the thread cutting will be described with reference to FIGS. That is, thread cutting is performed by the tap shaft unit 9. First, tap shaft 27
Is located at the origin position as described above. Therefore, the distance from the origin position to the bottom of the prepared hole 3a is divided by the pitch of the tap shaft 27 (the pitch of the threaded portion between the tap shaft 27 and the screw bush 35 and the pitch of the cutting tap 47 are also the same). The tap shaft 27 is rotated by the rotation speed. As a result, it is possible to accurately perform thread cutting to the bottom of the prepared hole 3a. For example, as shown in FIG. 4, the distance from the origin position to the bottom of the prepared hole 3a is 5 mm, and the pitch is 0.4 mm. In this case, 5 / 0.4 = 1
2.5, and the tap shaft 27 may be rotated only 12.5 times. This is executed by controlling the rotation of the tap axis control servomotor 11. For example,
Assuming that the encoder 13 outputs 2500 pulses per rotation, the amount of movement of the tap shaft 27 per pulse is 0.4 mm × 1/2500, and 0.00016
mm. Therefore, a desired threading process can be performed with extremely accurate dimensions.

According to the present embodiment, the following effects can be obtained. First, a threaded structure of the tap shaft 27 and the screw bush 35 is provided, and the pitch of the threaded structure is the same as the pitch of the cutting tap 47, and
Servo motor for tap axis control 1
1, the tap shaft 27 can be accurately moved a predetermined distance from the origin position. Therefore, by accurately calculating the distance from the origin position of the tap shaft 27 to the bottom of the pilot hole 3a, and dividing the distance by the pitch of the screw structure,
If the rotation amount of the tap shaft 27 is calculated and the tap shaft control servomotor 11 is rotated by that amount, the tap shaft 27 can be accurately fed by a predetermined amount. Thereby, a desired threading process can be performed accurately and easily to the bottom of the prepared hole 3a. In this case, since only the rotation amount of the tap axis control servomotor 11 needs to be controlled when performing the thread cutting, the control is significantly larger than the conventional two-axis simultaneous control or three-axis simultaneous control. Therefore, the configuration (the configuration including the control program) for that is also simplified. And the cost as an apparatus can be reduced correspondingly. Further, when changing the pitch, only the tap shaft 27 and the screw bush 35 need to be replaced, and the replacement operation is extremely simple.

Next, a second embodiment of the present invention will be described with reference to FIGS. This embodiment shows an example in which the thread cutting device according to the present invention is incorporated in an automatic lathe. First, the overall configuration of the apparatus will be described with reference to FIG. There is a bed 71 and this bed 7
A headstock table 73 is installed on the left side of FIG. A headstock 75 is installed on the headstock table 73 so as to be movable in the Z-axis direction (left-right direction in the figure). The headstock 75 holds the spindle 77 rotatably.
The headstock 75 is driven by a headstock driving unit 79, and thereby moves in the Z-axis direction (the left-right direction in the figure).

A facing table 81 is provided on the bed 71 and on the side (the right side in the figure) facing the headstock table 73. The facing table 81 is moved by the facing table driving section 83 in the ZB-axis direction parallel to the Z-axis direction already described. A tool table 85 is provided on the facing table 81. The tool table 85 is moved in the XB-axis direction orthogonal to the ZB-axis direction by the tool table drive unit 87. Since the facing table 81 moves in the ZB-axis direction, the tool table 85 eventually moves in two orthogonal directions, that is, in the ZB-axis direction and the XB-axis direction.

On the tool table 85, a base 89 is provided. Also, the headstock table 73
A guide bush 91 is provided between the table 81 and the facing table 81. On the upper side of the guide bush 91,
A tool post 93 is provided (indicated by a virtual line in FIG. 5),
A plurality of cutting tools 95 are attached to the tool rest 93. The plurality of cutting tools 95 are attached to the spindle 7
7 is mounted so as to be slidable in the direction perpendicular to the axial direction of the shaft 7. The sliding positioning allows the blade to be selected and the sliding control to be performed in the direction perpendicular to the sliding direction. It becomes.

A rotary tool unit 97 is provided. The rotary tool unit 97 is installed so as to be slidable in a direction orthogonal to the axial direction of the main shaft 77, that is, in the X direction. It can slide up and down. The Z-axis control by the headstock 75 and the two-axis sliding control of the tool unit are performed on the shaft end face of the workpiece 76 (shown in FIGS. 7 and 9) gripped by the main shaft 77 fixed in rotation. It is configured to be able to process slopes and the like by the combination control. This processing is performed as a pre-processing of the later-described oblique hole processing.

A threading unit 101 is mounted on the main body base 89 described above. Hereinafter, the configuration of the threading unit 101 will be described with reference to FIGS.
This will be described with reference to FIG. First, there is the base 103,
The base 103 has a mounting portion 105 at a front portion thereof and an upright portion 107 at a rear portion thereof. or,
The base 103 has three fixing screws 109 and 11
1 and 113, it is fixed on the main body base 89. At this time, it is attached and tilted at an appropriate angle around the fixing position by the fixing screw 109.
It has a fixable configuration. That is, the fixing screw 1
Looking at the 01 side, a plurality of screw holes 115 are formed in a predetermined arc on the main body base 89 side. Similarly, on the fixing screw 113 side, a plurality of screw holes 115 are formed on the main body base 89 side. The screw holes 117 are formed. Then, the base 103 is rotated by an appropriate angle around the position fixed by the fixing screw 109, so that an arbitrary screw hole 1 is formed.
By screwing the fixing screws 111 and 113 using the screws 15 and 117, the base 103 can be fixed to the main body base 89 in a state where the base 103 is inclined at an arbitrary inclination angle. In the case of this embodiment, as shown in FIGS. 7 and 9, the distal end surface 76a of the work 76 is machined as a 15 ° inclined surface. Mounted and fixed at a 15 ° tilt angle. At this time, as shown in FIG.
The desired angle (15 °) is obtained by pressing the angle gauge 114 against the angle.

The mounting portion 105 at the front of the base 103 has pneumatic motor spindle units 127 and 12
9 are attached, and a center drill 1 is attached to these pneumatic motor spindle units 127 and 129.
31 and the prepared hole drill 133 are attached respectively. When a desired threading process is performed on the distal end surface 76a of the work 76, first, a center hole is formed on the distal end surface 76a by the center drill 131. Next, a drill is made by a pilot hole drill 133 to prepare a pilot hole 78.
(Shown in FIG. 9; FIG. 9 shows a state in which the pilot hole 78 has been subjected to thread cutting). Then, the pilot hole 78 is subjected to thread cutting by the tap shaft unit 9. The configuration of the tap shaft unit 9 is the same as that of the first embodiment, and the same portions are denoted by the same reference numerals and description thereof will be omitted.

The thread cutting will be described based on the above configuration. In this case, the tip of the work 76 protrudes from the guide bush 91, and the tip surface 76a is machined as a 15 ° inclined surface by the rotary tool unit 97. Therefore, the threading unit 101 is also set to be inclined by the same angle. First, with the center drill 131,
Center hole processing is performed on the tip end surface of the work 76. That is, the control in two directions of the XB direction and the ZB direction is executed, whereby the movement of the center drill 131 is controlled in a predetermined direction. Next, a pilot hole is formed by a pilot hole drill 133. Also in this case, the XB direction, ZB
The control in two directions is performed, whereby the prepared hole drill 133 is controlled to move in a predetermined direction,
A pilot hole 78 will be formed.

Next, threading is performed by the tap shaft unit 9. In this machining, the tapping unit is moved to a predetermined position with respect to the threading surface (slope) by a two-axis control by the driving unit 83. The shaft unit 9 is moved, and the threading process is the same as in the first embodiment. For example, as shown in FIG. 9, the distance from the origin position to the bottom of the prepared hole 78 of the work 76 is 5 mm, and the pitch is 0.4 mm. In this case, 5 /
0.4 = 12.5, and the tap shaft 27 may be rotated only 12.5 times. This is executed by controlling the rotation of the tap axis control servomotor 11. For example, the encoder 13 has 2500 rotations per rotation.
Assuming pulse output, the movement amount of the tap shaft 27 per pulse is 0.4 mm × 1/2500,
0.00016 mm. Therefore, a desired threading process can be performed with extremely accurate dimensions.

Next, a case in which the threading unit 101 is machined without tilting will be described with reference to FIGS. That is, in the case described above, the thread cutting unit 101 is connected to the tip end surface 76a of the workpiece 76.
In this embodiment, the tip surface 76a of the work 76 protruding from the guide bush 91 side is not an inclined surface but a parallel surface. In this case, the screw processing unit 101 may be set without tilting, as shown in FIGS. Note that the operation is the same as that in the case of the above-mentioned inclination, and the description thereof will be omitted.

Therefore, also in this embodiment,
The same effects as in the case of the first embodiment can be obtained. Further, in the case of this embodiment, since all are unitized, including the center drill 131 and the pilot hole drill 133, and are configured as the threading unit 101, there is an advantage that the working efficiency is high. .
Further, since the threading unit 101 can be set to be arbitrarily inclined, it is possible to easily cope with the case where the single surface 76a of the work 76 is inclined without requiring complicated control.

Next, a third embodiment of the present invention will be described with reference to FIG. In the first and second embodiments, an example in which the cutting tap 47 is used as a cutting tool has been described. However, as shown in FIG. Also, it can be applied to processing of external threads. As shown in FIG. 13, the collet chuck mechanism 45 includes a cutting die holder 203.
Are inserted and fixed, and the cutting die holder 203 is inserted.
The cutting die 201 is held by a fixing screw 205. In such a case, similarly to the case of the first and second embodiments, by controlling the advance / retreat amount accurately by the threading shaft advance / retreat means, the tip of the cutting die 201 can be set at a predetermined position. It can be positioned accurately.

It should be noted that the present invention is not limited to the first to third embodiments, and the illustrated configuration is merely an example, and various modifications can be considered. For example, the second
As a modification of the above embodiment, a weather-resistant headstock may be installed alongside the threading unit. On the other hand, the number of control axes of the tap shaft unit also moves relatively depending on the balance with the control axis on the work side, and it is arbitrary as long as the thread cutting tool can be positioned at the home position with respect to the work.

[0031]

As described in detail above, according to the threading apparatus according to the present invention, the threading shaft can be accurately fed by a predetermined amount without requiring a complicated structure and without increasing the cost. Can be obtained.
Further, when the threaded structure portion is constituted by a male thread portion of a threaded shaft and a female thread portion of a screw bush detachably provided on the outer periphery thereof, the pitch can be reduced by replacing the threaded shaft with the threaded bush. Changes can be made easily.
In addition, when the cutting tool is used as a cutting tap and unitized including a center drill and a prepared hole drill, handling becomes easy. If the entire unit can be tilted, the angle of inclination can be determined according to the shape of the end face of the work, and necessary thread cutting can be performed. Only the axis needs to be controlled.

[Brief description of the drawings]

FIG. 1 is a view showing a first embodiment of the present invention, and is a plan view showing an entire configuration of a thread cutting apparatus and showing a part of the thread cutting apparatus cut out.

FIG. 2 is a diagram showing the first embodiment of the present invention, and is a cross-sectional view showing a part of FIG. 1 in an enlarged manner.

FIG. 3 is a view showing the first embodiment of the present invention, and is a view showing a process of returning a tap axis to an origin.

FIG. 4 is a view showing the first embodiment of the present invention, and is a cross-sectional view showing a state in which a prepared hole is subjected to thread cutting by a cutting tap.

FIG. 5 is a view showing a second embodiment of the present invention, and is a plan view showing a configuration of an automatic lathe incorporating a thread cutting device.

FIG. 6 is a view showing a second embodiment of the present invention, and is a perspective view showing a configuration of a thread cutting device.

FIG. 7 is a view showing a second embodiment of the present invention, and is a plan view showing a configuration of a thread cutting apparatus and showing a part of the apparatus cut out.

FIG. 8 is a view showing a second embodiment of the present invention, and is a side view showing a configuration of a thread cutting device.

FIG. 9 is a view showing a second embodiment of the present invention, and is a cross-sectional view showing a state in which a pilot hole of a work is subjected to thread cutting by a cutting tap.

FIG. 10 is a view showing a second embodiment of the present invention, and is a plan view showing a configuration of an automatic lathe incorporating a thread cutting device.

FIG. 11 is a view showing a second embodiment of the present invention, and is a perspective view showing a configuration of a thread cutting device.

FIG. 12 is a view showing a second embodiment of the present invention, and is a plan view showing a configuration of a thread cutting apparatus and showing a part of the apparatus cut out.

FIG. 13 is a view showing a third embodiment of the present invention, and is a cross-sectional view showing a state in which a cutting die is attached to a collet chuck.

[Explanation of symbols]

 Reference Signs List 3 work 5 thread cutting device 9 tap shaft unit 11 servo motor (drive motor) for tap shaft rotation control 27 tap shaft (thread cutting shaft) 35 screw bush 39 male screw portion provided on tap shaft 41 female screw portion provided on screw shaft 47 Cutting Taps (Cutting Tools)

Claims (4)

[Claims] 1. A drive motor whose rotation can be controlled, a threading shaft that is rotated by rotation of the driving motor, a cutting tool that is attached to a tip of the threading shaft, has an arbitrary pitch, and performs threading on a workpiece. And a threading shaft advancing / retreating means for providing a threaded structure provided on the threading shaft and having the same pitch as the pitch of the cutting tool, and for advancing and retreating the threading shaft rotated by the rotation of the drive motor by a predetermined amount. A threading device. 2. The threading device according to claim 1, wherein the threaded structure of the threaded shaft advance / retreat means is attached to and detached from a male thread formed on the threaded shaft while rotation is restricted by the outer periphery of the threaded shaft. And a female threaded portion formed on the screw bush so as to be capable of being screwed into the male threaded portion, and when changing the pitch, the threaded shaft and the screw bush are exchanged. Threading machine. 3. The thread cutting device according to claim 1, wherein the cutting tool is a tap for cutting, and a center drill and a prepared hole drill are provided side by side to form a unit. 4. The thread cutting apparatus according to claim 3, wherein the entire unit can be inclined at a predetermined angle with respect to the workpiece.