JPH0549413B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a tap holder that holds a tap and is attached to the main shaft of a machine tool, and performs female thread machining as the main shaft rotates.

Conventional technology Conventionally, when tapping a screw on a machining center, the rotation of the main shaft and the feed are usually not synchronized, so a spring is interposed between the holder body and the tap, and the expansion and contraction of the spring is The thread was tapped while absorbing the difference between the pitch of the female thread and the feed of the tap. Therefore, the amount of expansion and contraction of the spring differs for each female threaded hole, resulting in a disadvantage that the tapping depth tends to vary.

On the other hand, in dedicated machines, a lead screw was provided on the machine side to synchronize the rotation of the main shaft and the feed, but this inevitably increased the cost of the machine.

Therefore, the present applicant filed an earlier application (Japanese Patent Application No.
No. 130034), we proposed a tap holder that is equipped with a lead screw shaft and can feed the tap in synchronization with its rotation. This tap holder includes (a) a holder body that has an engaging part that engages with a drawbar provided inside the main shaft and is fixed to the main shaft by the drawbar, and (b) a holder body that is rotatable relative to the holder main body and that is rotatable in the axial direction. (c) a female threaded member that is mounted in a relatively immovable manner and has a female threaded hole in the center, and (c) a non-rotating member that engages with the female threaded member and is provided around the main shaft when the holder body is fixed to the main shaft. (d) a rotation prevention device that is removably engaged with the member in the axial direction of the main shaft and prevents rotation of the female threaded member; and a lead screw shaft having a tap retaining portion that concentrically holds the tap at a distal end protruding from the holder body, and the holder body is rotated by the main shaft. The tap is rotated via the lead screw shaft, and a feed rate determined by the pitch of the lead screw is applied to the tap. This tap holder can be quickly attached to and removed from the main spindle of a machine tool in the same way as other cutting tools, improving the accuracy of tapping depth. Since there is no need to provide any equipment, the structure is simple and the manufacturing cost is low.

This application also proposes detecting the stroke end of a tap using a stroke end detection device. This is intended to further improve the accuracy of tapping depth by detecting the stroke end of the tap and stopping the rotation of the main shaft when the tap reaches the forward end.

Problems to be Solved by the Invention However, when trying to detect the stroke end of a tap and stop it in this way,
In addition to the stroke end detection device, a device that quickly stops the rotation of the spindle, a control device that controls the drive device or stop device of the spindle based on the signal from the stroke end detection device, and a stroke end detection device There is a risk that the tap may malfunction, and since there is a certain time interval between detecting the stroke end and when the tap completely stops, tapping may be performed unnecessarily during that time, especially when tapping at high speed. When machining is attempted, the amount of machining to be performed during that time also increases, creating a problem in which it becomes difficult to control the tapping depth.

In other words, the previously developed tap holder still has problems to be solved in terms of the accuracy of tapping depth, speeding up machining, and reliability of operation.

Means for solving the problem No. 1 The invention of the present application was made in order to solve this problem. Therefore, the gist of the first invention of the present application is to provide a tap holder which is attached to the main spindle of a machine tool while holding a tap and performs female thread machining as the main spindle rotates; (a) provided inside the main spindle; (b) a holder body having an engaging part that engages with a drawbar which is attached to the main shaft and fixed to the main shaft by the drawbar; (c) a female threaded member that cannot move relative to the holder body in the axial direction when the holder body is installed; (d) a rotation prevention device that removably engages with the non-rotating member in the axial direction of the main shaft to prevent rotation of the female threaded member; and (d) is provided to allow relative rotation and relative movement in the axial direction with respect to the holder body. (e) a lead screw shaft which is screwed into the female threaded hole in the male threaded part and holds the tap concentrically at the tip opposite to the holder body; (f) at least one drive member biased radially inward by a means; A bidirectional rotation transmission section that transmits rotation in both directions, a forward rotation transmission section that is provided in front of the bidirectional rotation transmission section and transmits only rotation in the forward direction by engagement with a drive member, and a bidirectional rotation transmission section that transmits rotation in both directions. The driving member is configured to include a driven member having a reverse rotation transmission portion provided at the rear and transmitting only rotation in the opposite direction by engagement with the driving member.

Effects and Effects That is, the present invention provides a clutch including a driving member and a driven member between the holder body and the lead screw shaft, and transmits rotational torque by the clutch, while preventing the lead screw shaft from advancing. The transmission of rotational torque is cut off at the end, thereby stopping the feeding and rotation of the tap.

In such a tap holder, machining is stopped unconditionally as soon as the tap reaches the forward end, and there is no time interval between when the tap reaches the forward end and when it stops. Therefore, there is no possibility that the tapping process will be performed unnecessarily. Therefore, the accuracy of the tapping depth is improved.

Moreover, this means that the rotation and feed speed of the tap,
In other words, since it is not affected by a slow machining speed, by using such a tap holder, it is possible to solve the problem of difficulty in controlling the tapping depth when tapping is performed at high speed.

In addition, in this tap holder, the tap is mechanically stopped when it reaches the forward end, so unlike the case where a stroke end detection device detects the stroke end of the tap and stops it, malfunction of the device may occur. Therefore, there is no fear that the tap will not stop at the forward or backward end, or will stop on the way to the stroke end. In other words, this tap holder has high operational reliability.

In addition, since no expensive control device is required, machine tools or tap holders can be manufactured at low cost.
Moreover, since the clutch has a simple structure including a driving member held movably in the radial direction in the holder body and a driven member integrally provided with the lead screw shaft, it can be manufactured at a lower cost. can do.

Means for Solving Problem No. 2 The gist of the second invention of the present application for solving the above problem is to remove (c) the rotation prevention device from the tap holder according to the first invention, and instead,
(g) A positioning member that is provided on the outside of the lead screw shaft so as to be relatively rotatable and that is provided in a fixed position around the main shaft and removably engages with the positioning member in the axial direction of the main shaft to adjust the position of the center line. a casing whose angular position about the centerline is determined; and (h) a plurality of positions of the casing offset from the axis of the lead screw shaft;
The tap is provided so as to be relatively rotatable around an axis parallel to the axis of the lead screw shaft and movable in the axial direction, and is provided with a tap holding part for holding the tap concentrically at each end protruding from the casing. A plurality of small spindles and (i) a transmission provided between the plurality of small spindles and the lead screw shaft to synchronously transmit rotation and axial movement of the lead screw shaft to the plurality of small spindles; The reason is that the device is configured to include the device.

Functions and Effects In such a tap holder, feed and rotation synchronized with the rotation of the main spindle are applied to the taps held by multiple small spindles through the lead screw shaft, thereby allowing multiple tapping operations to be performed simultaneously. obtain. In other words, conventionally, only one tapping process could be performed in one machining cycle, but according to the present invention, multiple tapping processes can be performed in one cycle, thereby significantly speeding up the process. It will be enhanced. In addition, in the tap holder of the present invention, the lead screw shaft, and therefore the tap, is stopped immediately upon reaching the forward end, thereby allowing the tap to be fed and rotated at high speed.

That is, in the tap holder of the present invention,
The action of the clutch not only improves the accuracy of the tapping depth, but also has the effect of significantly shortening the tapping time.

In addition, since the casing is precisely positioned by engaging with the positioning member, and the casing positions the multiple small spindles and taps, the fitting surface of the spindle with the holder body may wear out. Even if the positioning accuracy of the holder body deteriorates, it is possible to maintain high accuracy in tapping.

Furthermore, if measures are taken such as making the tooth ratio of the gear that transmits the rotation of the lead screw shaft to the small spindles different for each small spindle, it will be possible to machine multiple screws with different pitches in one machining cycle. .

Embodiment Next, an embodiment in which the present invention is applied to a tap holder for a machining center will be described in detail with reference to the drawings.

In FIG. 1, 10 is a holder main body, which is composed of a first member 12, a second member 14, and a third member 16. Although the holder main body 10 is divided into a plurality of members for convenience of assembly, it functions as an integrated member after assembly. This holder main body 10 has a taper shank 20 on the rear side of the grip portion 18, and an outer circumferential tapered surface 22 of this taper shank 20 is tightly fitted and aligned with an inner circumferential tapered surface 26 of the main shaft 24. There is. Further, the rotational torque of the main shaft 24 is transmitted to the holder main body 10 by the engagement between the engagement convex portion 113 of the main shaft 24 and the notch 115 of the holder main body 10.

A through hole extending in the axial direction is formed in the center of the holder body 10. The rear end of the through hole is a female threaded portion 28, and a male threaded portion 32 of a pull stud 30 is screwed into this female threaded portion 28, so that the pull stud 30 is integrally connected to the holder body 10. The pull stud 30 is a part to which the pulling force of a drawbar (not shown) is applied, and when this pulling force is applied, the outer peripheral tapered surface 2 of the taper shank 20
2 is tightly fitted to the inner circumferential tapered surface 26 of the main shaft 24.

The front end of the through hole is a large diameter hole, and a cylindrical internally threaded member 34 with a flange is inserted into the holder main body 1.
It is arranged at a position concentric with 0. The female screw member 34 is held by the third member 16 via a radial bearing 36 and thrust bearings 38, 40, and is rotatable relative to the holder main body 10 and immovable in the axial direction.

A casing 52 consisting of a cylindrical first member 48 and a second member 50 is disposed in front of the holder main body 10. First member 48 and second member 5
0 is divided into parts for convenience of assembly, and becomes an integral member after assembly. An inward flange 54 is formed in this casing 52 at a portion adjacent to the holder main body 10 , and this flange 54
is tightened in the axial direction by the nut 56, thereby connecting the casing 52, the third member 16 of the holder body 10, the female threaded portion 34, and the thrust bearing 3.
8 and 40, and are coupled so as not to be relatively movable in the axial direction. The flange 54 of the casing 52 is further coupled to the female threaded member 34 via a key 58, so that the casing 52 and the female threaded member 34 cannot rotate relative to each other.

An arm 60 extends radially outward from the casing 52 . A cylindrical portion 61 is formed at the tip of the arm 60, and a positioning pin 66 is slidably fitted into a fitting hole 62 inside the cylindrical portion 61 via a sleeve 64. This positioning pin 66 is biased by a coil spring 68 in the direction of protruding from the fitting hole 62, and an engaging piece 70 is fixed to the protruding end with a bolt. This engagement piece 70 passes through a notch 72 formed in the cylindrical portion 61 and protrudes radially inward, and its tip engages with an engagement groove 74 formed in the holder body 10. There is. That is, the engagement piece 70 and the engagement groove 74
Relative rotation between the casing 52, that is, the female threaded member 34, and the holder body 10 is prevented when they are engaged, and when they are disengaged, the female threaded member 3
4 and the holder main body 10 can be rotated relative to each other. Note that this engagement piece 70
When the positioning pin 66 is in the most protruding state from the fitting hole 62, it engages with the engagement groove 74, and when the positioning pin 66 is pushed in a certain amount, the engagement groove 7
It is attached at a position where the engagement with 4 is released. On the other hand, the positioning pin 66 is for engaging a positioning block 67 as a non-rotating member provided around the main shaft 24 to prevent rotation of the casing 52 and the female threaded member 34, so that the holder main body 10 is attached to the main shaft 24. When installed, it engages with the engagement hole of this positioning block 67. In other words,
In this example, the positioning pin 66, the casing 52, the key 58, etc. constitute a rotation prevention device that prevents the female threaded member 34 from rotating.

A lead screw shaft 80 is screwed into the female thread member 34 at a male thread portion 82 . Lead screw shaft 80
includes a first member 76 and a second member 78 connected to the first member 76 via the overload prevention mechanism 125.
and a casing 52 of the second member 78.
A tap holder 116 is provided at the end projecting from the holder, and a tap 120 is concentrically attached thereto via an adapter 118. The adapter 118 uses a bayonet joint that can be quickly attached and detached, but since it is a well-known type, a detailed explanation will be omitted here.

An engagement groove 86 is formed in a shaft portion 84 of the lead screw shaft 80 that projects rearward from the female screw member 34, and a drive pin 88 having a rectangular cross section is inserted into the engagement groove 86. The drive pin 88 is slidably fitted into a fitting hole 90 with a rectangular cross section formed in the radial direction of the holder main body 10, and is radially fixed by a spring 94 whose one end is brought into contact with a retaining screw 92. The engagement groove 8 is biased inward by the biasing force.
It has been forced into 6. On the other hand, the engagement groove 86
As shown in FIG. 2, the vertical groove 9 extends in the axial direction.
6 and circumferential grooves 98 and 100 extending in the circumferential direction from both ends of the vertical groove 96. Vertical groove 9
One side wall surface 106 of 6 is continuous with an end surface 109 of the circumferential groove 98, and the other side wall surface 108 is continuous with an end surface 111 of the circumferential groove 100. The circumferential groove 98 on the front side extends in the opposite direction to the rotation direction when the main shaft 24 rotates in the opposite direction, that is, when tapping the screw, while the circumferential groove 100 on the rear side extends in the opposite direction to the direction of rotation when the main shaft 24 rotates in the opposite direction, that is, when tapping the screw. It extends in the direction of rotation. As shown in FIG. 3, these two circumferential grooves 98, 100 become shallower as they move away from the longitudinal groove 96, and have a depth of zero at the end. These circumferential grooves 98, 100 allow the drive pin 88 to fit into the circumferential groove 1 when the lead screw shaft 80 reaches its forward end.
00, and conversely, the position is selected in advance so that when the lead screw shaft 80 reaches the retracted end, it enters the circumferential groove 98. Therefore, these engagement grooves 86 and drive pins 88 transmit only the rotational torque in the positive direction of the holder body 10 to the lead screw shaft 80 when the lead screw shaft 80 is at the backward end, and when the lead screw shaft 80 is at the forward end. Sometimes only rotational torque in the opposite direction is transmitted, and these engagement grooves 86 and drive pins 88
means a clutch 11 that moves the lead screw shaft 80 forward and backward in the axial direction by a fixed distance from the retreating end and the advancing end.
It constitutes 0.

The front end portion of the first member 76 that constitutes the lead screw shaft 80 is a cylindrical shaft portion 114 that protrudes into the inside of the casing 52 and can slide on the inner circumferential surface of the second member 78 that is also formed in a cylindrical shape. The second member 78 is connected to the second member 78 via the overload prevention mechanism 125 in this state. The overload prevention mechanism 125 includes a radial through hole and a ball 122 formed in the first member 76 and the second member 78, and a rod cam 123 inserted into the cylindrical shaft portion 114.
and a disc spring 126. Belleville spring 1
The rod cam 123 has one end received by the cap nut 128 and exerts a biasing force on the rod cam 123, and the rod cam 123 applies the biasing force on the ball 122 at the cam surface 124, so that the ball 12
2 is partially inserted into the through hole of the second member 78. When the reaction force acting on the second member 78 during female thread machining is of a normal magnitude, this overload prevention mechanism 125 prevents the first member 78 from moving through the ball 122.
6 is transmitted to the second member 78, but when the reaction force becomes larger than a certain value, the ball 122 is pushed inward against the biasing force of the disc spring 126, and the rotation torque of the first member 78 is transmitted to the second member 78. Transmission of torque from member 76 to second member 78 is interrupted.

Next, the usage and operation of the tap holder will be explained. Before this tap holder is installed, the positioning pin 66 is in the most protruding state from the fitting hole 62, and therefore the engagement piece 70 is in the engagement groove 74.
The holder main body 10 is engaged with the holder body 10, the casing 52, and the internally threaded member 34 to prevent relative rotation therebetween. In this state, the grip part 18 is gripped by the tool changing arm of the machining center, the taper shank 20 is inserted into the center hole of the main shaft 24, and a retracting force is applied to the prestad 30 from a drawbar (not shown), so that the taper shank 20 is The main shaft 24 is tightly fitted. In this process, the positioning pin 66 first engages with the engagement hole of the positioning block 67 to prevent rotation of the casing 52 and the female threaded member 34, and is pushed into the engagement hole 62 by the bottom surface of the engagement hole and engaged. Piece 7
0 is disengaged from the engagement groove 74, and the holder main body 10 is made rotatable.

Next, the main shaft 24 or the workpiece is moved to bring the tap 120 and the workpiece closer together, and when they have approached a certain amount, the main shaft 24 is rotated. At this point, the lead screw shaft 80 is at the retracted end shown in FIG. The main body 10 is the main shaft 2
4 and the notch 11 of the holder body 10
5, the rotational torque is transmitted to the lead screw shaft 80 by the engagement with the end surface 109 of the drive pin 88, and the lead screw shaft 80 starts rotating. Lead screw shaft 80 starts rotating
is advanced to the right in FIG. 1 by the screw feeding action of the female thread member 34 and the male thread portion 82, and
0 is given rotation and feed synchronized with the rotation of the main shaft 24. As a result, the female threads corresponding to the thread pitches of the tap 120 and the lead screw shaft 80 can be accurately machined.

As this female thread machining progresses, the drive pin 88 slides on one side wall surface 106 of the vertical groove 96.
The female thread is machined to a predetermined depth, and the lead screw shaft 8
0 reaches a predetermined forward end, it separates from the side wall surface 106 and enters the circumferential groove 100, no longer transmitting rotational torque. The transmission of rotational torque by clutch 110 is cut off, and tap 1
The feed and rotation of 20 is immediately stopped.

Next, when the main shaft 24 is reversed, the rotational torque is transmitted to the lead screw shaft 80 based on the engagement of the drive pin 88 with the end surface 111, and the lead screw shaft 80 is reversed and retreated.

When the lead screw shaft 80 reaches the retracted end, the drive pin 88
is removed from the side wall surface 108 and no longer transmits rotational torque, and the rotation and retraction of the lead screw shaft 80 are stopped, thus completing one cycle of female thread machining.

As is clear from the above description, in this example, the drive pin 88 functions as a driving member, the shaft portion 84 of the lead screw shaft 80 functions as a driven member, and the vertical groove 96 of the shaft portion 84 functions as a driven member. The portion having the circumferential groove 98 constitutes a bidirectional rotation transmitting portion, the portion having the circumferential groove 98 constitutes a forward rotation transmitting portion, and the portion having the circumferential groove 100100 constitutes a reverse rotation transmitting portion.

The tap holder of this example can be quickly mounted and used on the main shaft 24 in the same way as other cutting tools. In the attached state, the rotational torque of the holder main body 10 is transmitted to the lead screw shaft 80 via the clutch 110, and the lead screw shaft 80
At the forward end of the motor, the clutch 110 is naturally disengaged and the transmission of rotational torque is cut off. Therefore, when the lead screw shaft 80 and the tap 120 reach their forward ends, their feeding and rotation are immediately stopped, so that the dimensional accuracy of the tapping depth in the tapping process is improved.

Further, as soon as the lead screw shaft 80 reaches the forward end, the transmission of rotational torque is cut off, so even if the lead screw shaft 80 and the tap 120 are rotated and moved forward at high speed, even after they reach the forward end. There is no possibility that female thread machining will be performed before the machine stops. In other words, the tap holder of this example is capable of feeding and rotating the tap at high speed while maintaining high accuracy in tapping depth, and furthermore, the tap can be stopped immediately when it reaches its retreating end. By using such a tap holder, it becomes possible to perform thread tapping at high speed. In addition, the clutch 110 reliably interrupts torque transmission at the forward and backward ends of the lead screw shaft 80 and the tap 120, and is controlled by a stroke end detection device, a control device, etc.
There is no risk of malfunction as would be the case if the system is stopped. Therefore, the reliability of the tapping process is improved, and the device has the advantage of being manufactured at a low cost.

A second embodiment of the present invention will be described based on FIGS. 4 to 8.

In this example, the holder main body 10 and the casing 130 are separated, the grip portion 18 is formed on the casing 130 side, and the lead screw shaft 80 is formed on the casing 130 side.
is held by the casing 130 at a position substantially concentric with the axis of the casing 130, and the lead screw shaft 80 can be slightly displaced in the radial direction with respect to the holder body 10 together with the casing 130; This embodiment differs from the embodiment described above in the structure of the clutch that transmits the rotational torque of 1 to the lead screw shaft 80. Here, only these different parts will be explained, and the same parts as in the above embodiment will be given the same reference numerals and detailed explanation will be omitted.

In the figure, a casing 130 includes a plurality of members, ie, a first member 132, a second member 134, a third member 136, and a fourth member 1, as in the previous embodiment.
It consists of 38 pieces. The internally threaded member 140 is directly fixed to this casing 130 by bolts 144 at the flange 142, and the casing 13
Relative rotation with respect to 0 is prevented. The lead screw shaft 80 screwed into the female threaded member 140 is tightly fitted at its front end into an oil-less guide bushing 145 held by the fourth member 138 of the casing 130, with its axis centered at the center of the casing 130. It is precisely positioned in line with the line. First member 1 of casing 130
32 is formed with a tapered surface 148 and an end surface 146 extending radially outward from the large diameter side of this tapered surface 148, and these tapered surface 148 and end surface 146 surround the spindle 24 when the headstock is closed. By closely contacting the tapered surface 154 and end surface 152 of the positioning member 150 fixed to the casing 130, the casing 130 is accurately positioned at a position where its center line coincides with the axis of the main shaft 24. It's summery. Further, although not shown, an engaging protrusion is formed on the end surface 152 of the positioning member 150, while the casing 130
A cutout that can be engaged with the end face 146 of the casing 130 is formed in the end face 146 of the casing 130.
rotation is now prevented. In this example, these engaging protrusions and notches are located on the casing 1.
Together with 30, it constitutes a rotation prevention device for the female threaded member 140.

The casing 130 includes disc springs 156 in a plurality of circular recesses provided on one circumference, and a plate 15.
8. Thrust bearing 160 and nut 16
2, the cylindrical shaft portion 14 of the holder body 10
9, and is capable of relative movement over a short distance in the axial direction with respect to the holder body 10 based on the elastic deformation of the disc spring 156. Further, there is a radial angle between the casing 130 and the cylindrical shaft portion 149 and between the lead screw shaft 80 and the cylindrical shaft portion 149, respectively.
A gap is formed between the casing 130 and the lead screw shaft 80 so that the casing 130 and the lead screw shaft 80 can be slightly displaced in the radial direction with respect to the holder main body 10.

Further, in this example, a stroke end detection device is provided which detects the stroke end of the lead screw shaft 80 based on a change in air pressure. In this stroke end detection device, the air is supplied from the air supply port 168 of the positioning member 150, passes through the air passage 17, is discharged into the casing 130 from the air discharge port 172, and is further discharged to the outside from the discharge port 174. The arrival of the lead screw shaft 80 at the forward end is detected by detecting the change in air pressure when the lead screw shaft 80 closes the discharge port 172 at the forward end. It is. Although not shown, the retracted end of the lead screw shaft 80 is also detected in the same manner.

In the tap holder of this example, in the detached state, the casing 13 is held under the biasing force of the disc spring 156.
The rear surface of the holder body 10 is in close contact with the front surface of the holder body 10, and the holder body 10 and the casing 130 are engaged by the engagement convex portion 176 provided in the holder body 10 and the engagement hole 178 provided in the casing 130. The rotational positions of the two are aligned.

In this state, the taper shank 2 of the holder body 10
0 is inserted into the center hole of the main shaft 24, first the tapered surface 148 of the casing 130 and the end surface 1
46 contacts tapered surface 154 and end surface 152 of positioning member 150, and then pull stud 30
(not shown in FIG. 4), when a retraction force is applied from the drawbar, the taper shank 20 of the holder body 10 moves in the axial direction while elastically deforming the disc spring 156, and the outer circumferential tapered surface 22 of the shank 20 moves in the axial direction while elastically deforming the disc spring 156. The tapered surface 148 and end surface 146 of the casing 130 are tightly fitted to the inner circumferential tapered surface 26 .
is pressed against the tapered surface 154 and end surface 152 of the positioning member 150 under a constant load by the biasing force of the disc spring 156, so that the casing 13
0, the female screw member 140 and the lead screw shaft 80 are fixed to the positioning member 150 in an accurately positioned state.

In this tap holder, the holder body 10
The outer circumferential tapered surface 22 of the main shaft 24 and the inner circumferential tapered surface 2 of the main shaft 24
Even if the lead screw shaft 80 and the tap 120 at its tip are worn out or chips, dust, etc. adhere therebetween and an error occurs in the installation of the holder body 10 to the main shaft 24, the lead screw shaft 80 and the tap 120 at its tip will accurately positioned by Therefore, by using this tap holder, not only can the accuracy of the tapping depth be improved based on the action of the clutch, but also the
The positional accuracy of the center line of the screw hole can also be improved.

Next, the clutch that transmits the rotational torque of the holder body 10 to the lead screw shaft 80 will be explained.

In this example, the rear end of the lead screw shaft 80 has a pair of notches 22 extending in the circumferential direction at positions spaced apart in the axial direction, as shown in FIGS. 5 to 8.
2 and 224 are formed, and a notch 220 with an arcuate cross section connecting these is formed along the axial direction, and furthermore, at the ends of these notches 222 and 224, engagement surfaces 226 and 2 that rise outward in the radial direction are formed.
28 are provided. Of these, 22 notches
The depth gradually decreases as 2, 224 progresses in the circumferential direction, and the depth becomes zero at a position approximately 3/4 rotation from the engaging surfaces 226, 228, and the bottom surface of each is at the outer periphery of the lead screw shaft 80. connected to the surface.

On the other hand, the holder main body 10 is provided with two fitting holes 242 and 244 having a rectangular cross section extending in the radial direction at opposing positions.
A pair of drive pins 230 and 232 having a large diameter and a rectangular cross section are fitted into the pins 2 and 244. These drive pins 230, 232 each have one end connected to a spring retainer 234,
The springs 23 are brought into contact with 236, respectively.
8,240. One drive pin 230 engages with the engagement surface 228 on its side surface to transmit the rotational torque in the positive direction of the holder body 10 to the lead screw shaft 80, and the other drive pin 232 engages with the engagement surface 228. 226
and transmits the rotational torque of the holder body 80 in the opposite direction to the lead screw shaft 80, and constitutes a unidirectional first clutch 235 and a second clutch 237 together with the engaging surfaces 228 and 226, respectively. ing.

FIG. 4 shows a state in which the lead screw shaft 80 is at the retracted end, and in this state, one of the drive pins 2
30 has entered into the notch 222, and the other drive pin 232 is in a state riding on the outer peripheral surface of the lead screw shaft 80. When the main shaft 24 is rotated in this state, as shown in FIG. rotate in the forward direction and move forward at the same time. As the lead screw shaft 80 moves forward, the drive pin 230 relatively moves backward along the engagement surface 228 within the notch 220 of the arcuate cross section, and when the lead screw shaft 80 reaches the forward end, the engagement surface 228
8 and no longer transmits rotational torque.
During this time, the other drive pin 232
, the lead screw shaft 80 reaches the retracted end, and the drive pin 232 moves backward in the notch 220.
Notch 2 at the same time when relatively moving in the circumferential direction within 4
24 and circumferentially spaced from the engagement surface 226 .

Next, when the main shaft 24 is rotated in the opposite direction, the drive pin 232, which has been separated from the engagement surface 226, engages the engagement surface 226 again and transmits the rotational torque of the holder body 10 to the lead screw shaft 80. Retract the lead screw shaft 80. When the lead screw shaft 80 reaches the retraction end,
The drive pin 232 separates from the engagement surface 226, enters the notch 222, and no longer transmits torque.
During this time, the other drive pin 230 relatively moves in the axial direction along the engagement surface 228, and at the same time as the lead screw shaft 80 reaches the retracted end, moves together with the drive pin 230 in the circumferential direction within the notch 222 and engages. away from surface 228. When the holder main body 10 is rotated in the forward direction again, the lead screw shaft 80 engages with the engagement surface 228 and transfers the rotational torque of the holder main body 10 in the forward direction to the lead screw shaft 80 again.
to communicate.

As is clear from the above description, in this example, the two drive pins 230 and 323 function as driving members, and the rear end of the lead screw shaft 80 functions as a driven member, and the engagement Surfaces 226, 22
The portions facing each other across the notch 220 of No. 8 are bidirectional rotation transmission portions, and the notch 222 and the portion of the engagement surface 228 corresponding to the notch 222 are forward rotation transmission portions.
The notch 224 and a portion of the engagement surface 226 corresponding to the notch 224 each constitute a reverse rotation transmission section.

Next, a third embodiment of the present invention will be described based on FIG. 9. The tap holder of this example has a lead screw shaft 80.
This embodiment differs from the previous embodiment in that a plurality of small spindles 194 are connected to each other, and a tap 120 is attached to each of the small spindles 194.

In the figure, a casing 180 includes a first member 132 and a plate-shaped second member 1, as in the previous embodiment.
82, a cylindrical third member 184, a plate-like fourth member 186, and a fifth member 188 as a cap that closes a through hole in the center thereof. Positioning member 150 of casing 180
The relative rotational position with respect to is determined by the engagement between the engagement protrusion 164 and the notch 166. At the front end of the lead screw shaft 80 that protrudes into the inside of the casing 180, a gear 190 is attached to a boss portion 192 with a circular cross section.
and is connected to the end of the lead screw shaft 80 via the overload prevention mechanism 125. A slide plate 198 that is slidable in the axial direction along the inner circumferential surface of the casing 180 is fitted on the outside of the boss portion 192 of the gear 190 in a hole at the center thereof. The slide plate 198 is
By being fitted into the boss portion 192 of the gear 190 via the radial bearing 212, the gear 19
While it is possible to rotate relative to nut 2
18 is tightened to the gear 190 via thrust bearings 214, 216, thereby making it impossible to move relative to the gear 190 in the axial direction.

On the other hand, an appropriate number of small spindles 194 are disposed in the casing 180 along the circumferential direction at positions radially apart from the axis of the lead screw shaft 80. These small spindles 194 are provided so as to protrude forward from the casing 180, and are slidably held at their intermediate portions by a guide bush 196 attached to the casing 180. These small spindles 194
The rear end portion of each of the shaft portions is a small diameter shaft portion 200, and a gear 210 having the same number of teeth is fixed to the end portion of the small diameter shaft portion 200. These gears 210 are meshed with the gear 190, and the rotational torque of the lead screw shaft 80 is transmitted to each small spindle 19 through these gears 190, 210.
4. Further, the small diameter shaft portion 200 is rotatably fitted into a through hole formed in the slide plate 198 via a radial bearing 202 and coupled to the slide plate 198 via thrust bearings 204 and 206 by a nut 208. and is adapted to be moved in the axial direction integrally with this slide plate 198. The gears 190, 210, slide plate 198, etc. constitute a transmission device that transmits the rotation and axial movement of the lead screw shaft.

In this tap holder, when the main shaft 24 is rotated, the lead screw shaft 80 is given rotation and feed synchronized therewith. The rotational torque of the lead screw shaft 80 is transmitted to each small spindle 194 via the gears 190, 210, and the axial movement of the lead screw shaft 80 is transmitted to each small spindle 194 via the slide plate 198. small spindle 1
94 is given rotation and feed in synchronization with the rotation of the main shaft 24. As a result, a plurality of internal threads can be machined at the same time. In this example, a plurality of gears 210
It is said that the number of teeth is the same, but these gears 210
It is also possible to make the ratio of the number of teeth between the gear 190 and the gear 190 different for each gear 210, and in this case, different types of female threaded holes are formed all at once in one machining cycle.

Note that the tap holder of this example has a holder main body 10.
Rotational torque from the clutch 11 to the lead screw shaft 80
This is similar to the first embodiment in that it is performed using 0.

Further, when the small spindle 194 holding the tap 120 is located radially apart from the axis of the lead screw shaft 80 as in this example, the axis of the lead screw shaft 80 is aligned with the main shaft 24. Even if the tap 120 is slightly tilted with respect to the axis, the amount of displacement of the tap 120 will be large. Correspondingly, the positional accuracy of the axis of the female thread tends to decrease. However, in the tap holder of this example, the lead screw shaft 80 and the small spindle 194 are accurately positioned by the casing 180 without being affected by the installation error of the holder body 10, so that the female threaded hole is Position accuracy will not be degraded.

When machining an internal thread using the tap holder of this example, it is possible to greatly speed up the machining of the internal thread while improving the accuracy of the tapping depth, and it is also possible to improve the accuracy of the position of the internal thread hole.

Several embodiments of the present invention have been described in detail above, but
The invention can be implemented in other ways.

For example, in all of the above embodiments, the rotation prevention device for preventing the relative rotation of the female threaded member is constituted by the casing itself, or a part thereof is utilized, but the rotation prevention device is provided completely separately from the casing. It is also possible to provide one. Furthermore, in the embodiment shown in FIG. 9, the transmission device for synchronously transmitting the rotation and feed of the lead screw shaft to the small spindle may be constructed in a different manner, or the clutch may be constructed in a manner different from the several examples described above. It is also possible to configure

In addition, the present invention can be realized with various modifications based on the knowledge of those skilled in the art without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a front sectional view of a tap holder which is an embodiment of the present invention. FIG. 2 is a front view of a main part of the lead screw shaft in FIG. 1, and FIG. 3 is a cross-sectional view taken at - in FIG. 1. FIG. 4 is a front sectional view of a tap holder according to a second embodiment of the present invention, and FIG. Figure 6, 7th
The figure and FIG. 8 are a cross-sectional view, a cross-sectional view, and a cross-sectional view, respectively, of FIG. FIG. 9 is a front sectional view of a tap holder according to a third embodiment of the present invention. 10: Holder body, 24: Main shaft, 34, 14
0: Female thread member, 52, 130, 180: Casing, 58: Key, 60: Arm, 66: Positioning pin, 80: Lead screw shaft, 82: Male thread portion, 8
4: Shaft portion, 86: Engagement groove, 88, 230, 23
2: Drive pin, 94, 238, 240: Spring, 96: Vertical groove, 98, 100: Circumferential groove, 1
10: Clutch, 116: Tap holding part, 12
0: Tap, 150: Positioning member, 164: Engaging protrusion, 166: Notch, 190, 210: Gear,
198: Slide plate, 220, 222, 2
24: Notch, 226, 228: Engagement surface, 235:
First clutch, 237: Second clutch.

Claims (1)

[Scope of Claims] 1. A tap holder that is attached to the main shaft of a machine tool while holding a tap, and performs female thread machining as the main shaft rotates, the tap holder comprising an engagement member that engages with a drawbar provided inside the main shaft. a holder body having a joint portion and fixed to the main shaft by a drawbar; and a holder main body having a female threaded hole in the center and being held in a relatively rotatable manner to the holder main body, and at least when attached to the main shaft, the holder main body is fixed to the main shaft by a drawbar; a female threaded member that cannot move relative to the main shaft; and a female threaded member that engages with the female threaded member and engages with a non-rotating member provided around the main shaft in the axial direction of the main shaft when the holder body is fixed to the main shaft. a rotation prevention device that removably engages to prevent rotation of the female threaded member; a rotation prevention device that is provided to allow relative rotation and relative movement in the axial direction with respect to the holder main body, and is screwed into the female threaded hole in the male threaded portion; a lead screw shaft that holds the tap concentrically at the tip on the opposite side of the holder body; and at least one lead screw shaft that is movably provided in the holder body in a radial direction and that is biased radially inward by biasing means. a driving member; a bidirectional rotation transmitting portion that is provided to be rotatable concentrically and integrally with the lead screw shaft and that transmits rotation of the holder body in both forward and reverse directions through engagement with the driving member; a forward direction rotation transmission section that is provided in front of the rotation transmission section and transmits only rotation in the forward direction by engagement with the drive member; and a forward direction rotation transmission section that is provided at the rear of the bidirectional rotation transmission section and engages with the drive member. 1. A tap holder with a lead screw shaft, comprising: a driven member having a reverse rotation transmission section that transmits only rotation in the opposite direction. 2 A tap holder that holds a tap and is attached to the main shaft of a machine tool, and performs female thread machining as the main shaft rotates, comprising: a holder body that is fixed to the main shaft; and a holder body that has a female threaded hole in the center. an internally threaded member that is held so as to be relatively rotatable and that cannot move relative to the holder body in the axial direction at least when attached to the main shaft; and a state that allows relative rotation and relative movement in the axial direction with respect to the holder body. at least one lead screw shaft provided in the holder body so as to be movable in the radial direction and biased radially inward by biasing means; a driving member; a bidirectional rotation transmission unit that is provided to be rotatable concentrically and integrally with the lead screw shaft and transmits rotation of the holder body in both forward and reverse directions through engagement with the driving member; the bidirectional rotation transmission unit; A forward direction rotation transmission section is provided at the front of the section and transmits only the rotation in the forward direction by engagement with the drive member, and a forward direction rotation transmission section is provided at the rear of the bidirectional rotation transmission section and transmits rotation in the reverse direction by engagement with the drive member. a driven member having a reverse rotation transmission portion that transmits only the rotation of the lead screw shaft; A casing that engages with a fixedly provided positioning member to determine the centerline position and angular position around the centerline; A plurality of tap holding parts that are provided to be rotatable around an axis parallel to the axis of the screw shaft and movable in the axial direction, and each end of which protrudes from the casing is provided with a tap holding part that holds the tap concentrically. a small spindle, and a transmission device that is provided between the plurality of small spindles and the lead screw shaft and transmits rotation and axial movement of the lead screw shaft to the plurality of small spindles in synchronization. A tap holder with a lead screw shaft.