JPH0796181B2 - Tool holder - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool holder for predicting breakage of a drill, tap or the like.

[0002]

2. Description of the Related Art If the discharge of chips during cutting with a drill is poor, the cutting torque increases and the drill becomes threaded, or if the drill is worn and processed at a constant feed, excessive thrust force is generated. , This sometimes caused the drill to buckle.

As a tool holder for detecting excessive torque and thrust load as described above, there is one previously filed by the present applicant (Japanese Patent Application No. 2-41678), which has a tool holder cylinder on a holder shaft. Is movably supported in the circumferential direction and in the axial direction, the tool holding cylinder is biased forward by a thrust load setting spring, and a plurality of detectors provided on the outer circumference of the holder shaft and the outer circumference of the tool holding cylinder are separated from each other. The detector shaft by the torsional force of the torsion coil spring that connects the holder shaft and the tool holding cylinder, and the contact surface is provided with an inclined surface that is inclined at a large angle with respect to the axial direction. Tools produced by thrust
The axial movement of the holding cylinder is changed at the position where the detector is provided.
They are converted into circumferential rotation by the engagement of the inclined surfaces.
The circle of the tool holder cylinder detector to the holder shaft detector.
It can be taken out as a change in the circumferential position.
It

[0004]

In the above-mentioned conventional tool holder, the tool holding cylinder and the outer peripheral portion of the holder shaft are engaged with each other by inclined surfaces provided at a large angle with respect to the axial direction. Axial movement is converted to rotational direction.

In such a tool holder, the axial movement amount of the tool holding cylinder affects the hole depth. This is because the thrust force exceeds the spring force of the thrust load setting spring, but the axial displacement of the tool holding cylinder due to this thrust force is such that the rotational deviation between the tool holding barrel and the holder shaft can be detected. In such a case, the overload thrust load is not detected and the hole is finished as normal processing, but the hole depth becomes shallow, and in the extreme case, the processing tolerance is exceeded.

Therefore, an object of the present invention is to improve the conversion mechanism of the conventional tool holder described above, to reduce the axial movement amount of the tool holding cylinder as much as possible, and to reduce the influence on the hole depth during drilling. Is.

[0007]

In order to solve the above problems SUMMARY OF THE INVENTION In the tool holder of the present invention, the tool holder respectively movably supported to the circumferential direction and the axial direction on the holder body, Hol
Align the outer circumference of the tool body and the outer circumference of the tool holder with
Switch is equipped with multiple detectors to detect the holder body and tool holder.
The spout is facing each other, and the holder body and tool holder
A spring that sets an overload is interposed between
The inclined surface that converts the axial movement of the holding body into the circumferential rotation is used.
The conversion mechanism used is rotating the tool holder from the detector.
A tool that is installed close to the center and is generated by overload thrust
The axial movement of the holding body with respect to the holder body is converted into the conversion mechanism.
The tool holder is converted into a circumferential rotation by
Side position of the tool holder side detector with respect to the side detector
It is characterized in that it can be taken out as a change in position .

Further, the conversion mechanism has a support shaft outer periphery projecting from the center of one of the holder body and the tool holding body toward the other member, and a support hole of the other member fitted into the support shaft. A guide groove may be provided so as to face each other on the inner circumference and be inclined with respect to the rotation axis of the tool holder, and a ball may be interposed between the guide grooves. In addition, the holder body and tool
From the center of one of the members to the other member
Inclined to the axis of rotation of the tool holder on the protruding support shaft
A cam groove is provided, and this cam groove is integrated with the other member.
The conversion mechanism is constructed by slidably fitting the provided guide pin.
You may.

[0009]

In the tool holder of the present invention, since the conversion mechanism utilizing the inclined surface is arranged inside the tool holder, the axial movement amount of the tool holder is determined by the distance from the center of the tool holder to the inclined surface. To the outer circumference of the tool holder, the amount of movement of the detector on the outer circumference of the holder in the circumferential direction is enlarged.

[0010]

1 and 2, a first embodiment of the present invention comprising a holder body 2 integrally connected to a spindle 1 of a machine tool and a tool holder 6 having a collet chuck 5 for holding a tool 4 at a tip thereof. An example tool holder 7 will be described. The holder body 2 is composed of a tapered portion 2a, a grip portion 2b integral with the tapered portion 2a, and a support shaft 3 extending downward from the center of the grip portion 2b. The support shaft 3 has a connecting cylinder 10 on the outer circumference of a holding cylinder 9.
Is integrally screwed, and the tool holder 6 configured by fitting the support cylinder 11 into the hollow formed by both members is fitted. In this fitted state, the support shaft 11
Guide grooves (lead grooves) 12 that are inclined with respect to the rotation axis of the tool holder 7 are formed in the support hole 11a and the outer periphery of the support shaft 3 that are formed in the guide hole 12 between the guide grooves 12. A converting mechanism 1 for converting the axial movement of the tool holding body 6 with respect to the holder body 2 into a circumferential rotation when at least the overload thrust load is applied to the tool 4 with the ball 13 interposed.
4 are configured. Reference numeral 15 is a return tube provided in the support cylinder 11 for circulating the balls 13.

As described above, the conversion mechanism 14 provided inside the tool holder 7 has a ball screw structure, and the balls 13 and the support shaft 3 and the support cylinder 11 are in rolling contact with each other, so that the friction force is small and the lead thereof is small. The angle is about 9 degrees.

A screw is attached to the connecting cylinder 10 of the tool holder 6.
One end of a coil spring (spring for setting overload ) 16 is connected, and the other end of the spring 16 is connected to the grip portion 2b of the holder pair 2 and transmits the rotation of the holder body 2 to the tool holder 6 during processing. ing. Further, as shown in FIG. 3, a spring 2 having a detection ring 19 in which a large number of locking holes 17 and two left and right pins 18 which are engaged with and disengaged from the coupling cylinder 10 are interposed between the connection cylinder 10 and the grip portion 2b.
The detection ring 1 is urged downward by
9 is integrally attached. Therefore, the torsional strength of the torsion coil spring 16 is such that the detection ring 19 is moved backward (upward in FIG. 2) against the spring force to disengage the engagement hole 17 and the positioning pin 18, and in that state. It is adjusted by engaging the locking hole 17 of the detection ring 19 and the positioning pin 18 after rotating 10 in the circumferential direction. Also,
The torsional strength of the torsion coil spring 16 is set so as to correspond to both the thrust load and the torque applied to the tool 4, corresponding to the smaller one of the maximum allowable thrust load and the maximum allowable torque.

As shown in FIG. 4, the outer circumference of the detection ring 19 is equiangularly spaced in the circumferential direction (angle θ (120 (120) shown in FIG. 5).
Three displacement detectors 21 are formed every (degrees).
As shown in FIG. 5, the displacement detector 21 has detection display portions 22 and 23 at both edges in the rotation direction of the tool holder, which indicate the start or end of detection by a proximity switch 35 described later.

Three reference detectors (projections) 24 project from the grip portion 2b toward the space between the adjacent displacement detectors 21. As shown in FIG. 5, each of the reference detectors 24 has a stepped shape with the center protruding, and both edges of the center protruding portion 25 in the rotational direction indicate the detection start or the detection end by the proximity switch 35 described later. 26 and 27, and a pair of detection regions 28 and 2 of the rotation deviation between the detection display units 26 and 23 and between the detection display units 22 and 27 during the rotation direction of 120 degrees.
9 are formed, and three pairs of such detection areas 28 and 29 are provided in the circumferential direction. These detection areas 28, 29
When the proximity switch 35 is detected, the proximity switch 35 is turned off. When one side surface of the displacement detector 21 and one side surface 30a of the low step portion 30 of the protrusion 24 are in contact with each other by the twisting force of the torsion coil spring 16 and the conversion mechanism 14, the other side surface 30b of the low step portion 30 is contacted. There is a slight circumferential play (a pulse count value corresponding to the absolute value 2a in FIG. 5 is larger than a set value t described later) between the detection display units 23 facing each other. And the pair of detection areas 28, 2
9, the central projection 25 and the displacement detector 21 are set to have the same circumferential length L (30 degrees).

One proximity switch 35 for detecting the detection areas 28 and 29 is attached to a bracket 37 fixed to the front surface of a spindle head 36 as shown in FIG. The signal from the proximity switch 35 is sent to the overload torque (or thrust load) determination means 40 shown in FIG.

In the discriminating means 40, 41 is a frequency-voltage converter 42 and a voltage-frequency converter 43, which averages the signal pulses from the proximity switch 35 and multiplies them by a predetermined multiple to make a predetermined number of references for one rotation of the spindle 1. A spindle angle pulse generator for generating a pulse, a gate circuit 44 that rises at the fall of the signal of the proximity switch 35 and falls at the rise (opens while the proximity switch 35 is OFF), 4
A counter 5 adds or subtracts the spindle angle pulse Ps input while the gate circuit 44 is open,
Reference numeral 46 is an addition / subtraction switching circuit for switching the addition or subtraction command to the counter 45 in one cycle of the ON / OFF signal of the proximity switch 35 and outputting the determination command signal to the comparison circuit 47 at the rising edge. At the same time, a comparison circuit for judging whether the count value in the counter 45 exceeds a preset value t set by the setting circuit 48, 49 is a reset circuit for resetting the counter 45 after the judgment by the comparison circuit 47, and 50 is a comparison circuit 47. The comparison result at is the set value t
Is an output circuit that outputs an overload torque (or thrust) detection signal as an output signal when it exceeds the limit. The set value t is set to a value obtained by adding an allowable value to the difference between the pulse count values of the counter 45 when the proximity switch 35 detects the pair of detection areas 28 and 29 when there is no load before cutting. Assuming that there is no manufacturing error, a pair of detection areas 2 in this embodiment.
The difference between the pulse count values at 8 and 29 is zero.

According to the above-described structure, the rotation of the holder body 2 during normal cutting is transmitted to the tool holder 6 via the torsion coil spring 16 for machining. The proximity switch 35 repeatedly outputs ON and OFF signals. The detection area 28 is turned off, and during this time, the gate circuit 44 opens and the spindle angle pulse Ps is added to the counter 45 under the addition command of the addition / subtraction switching circuit 46, and the proximity switch 35 detects the central protruding portion 25. ON
Then, the gate circuit 44 closes and switches to subtraction, and when the proximity switch 35 detects the detection area 29 again and turns off, the spindle angle pulse Ps is subtracted from the pulse count value added in the counter 45, and the proximity switch 35 is displaced. When the detector 21 is detected and turned on, a determination command signal is output and the count value in the counter 45 is compared with the set value t. In the case of normal processing, since the torsion coil spring 16 and the conversion mechanism 14 are in contact with one side surface of the displacement detector 21 and one side surface 30a of the low step portion 30 of the reference detector 24, the lengths of the detection regions 28 and 29 are small. Are the same, the count value in the counter 45 becomes zero, and the output signal of the overload torque is not output.

Next, a case where only the overload thrust load is generated in the tool 4 due to the tool wear will be described. The torsion coil spring 16 is not twisted until an overload thrust load exceeding the torsional strength of the torsion coil spring 16 is generated in the tool 4, and the displacement detector 21 and the reference detector 24 have the relationship shown in FIG. When an overloaded thrust load is generated on the tool 4, the tool holder 6 retracts with respect to the holder body 2, and this axial movement is converted by the conversion mechanism 14 into circumferential rotation that is opposite to the rotational direction. Therefore, the displacement detector 21 provided on the outer periphery of the tool holder 6 causes a rotation delay with respect to the reference detector 24, and the reference detector 24 relatively rotates by the play a shown in FIG. The side surface 30b of 30 abuts on the detection display unit 23. By this relative rotation, the circumferential length of the detection area 28 becomes L-a, and the circumferential length of the detection area 29 becomes L + a. Therefore, the result of addition in the detection area 28 and subtraction in the detection area 29 is -2a, and the absolute value 2a becomes larger than the set value t, so that the output signal of the overload thrust is output from the output circuit 50. By the output signal of this overload thrust, a stop command is output to the spindle drive motor or a step back operation is instructed. Furthermore, this output signal is counted by the life counter, and the count value in the life counter is the predetermined number of times. When it exceeds, the tool is replaced with a new tool that is the same as that tool even during machining.

By the way, the conversion mechanism 14 uses the detectors 21 and 21.
From the outer peripheral position where 4 is provided, the rotation center of the tool holder 7
Since it is provided at a position close to, that is, inside the tool holder 7, the axial movement amount of the tool holder 6 is changed by the conversion mechanism 14 at the position of the guide groove 12 of the conversion mechanism 14.
Is converted into a predetermined amount of movement in the circumferential direction that is determined by the inclination angle of the tool holder 7.
It is enlarged at the outer peripheral position according to the ratio of the radius from the rotation center to the guide groove 12 of the conversion mechanism 14 and the radius from the center to the detectors 21, 24. Therefore, the detectors 21, 24
The axial movement amount of the tool holder 6 required to move the detector in the circumferential direction by the amount of play a is equal to the conventional ratio.
It decreases to 1 . Moreover, since the conversion mechanism is a ball screw mechanism and the lead angle is small, the amount of movement in the axial direction is further reduced by this gentle lead angle. This reduces the influence of the axial movement amount of the tool holder 6 on the hole depth. The same operation as described above is also performed when only the overload torque exceeding the torsional strength of the torsion coil spring 16 or the overload torque and the overload thrust load are simultaneously generated in the tool.

Next, the tool holder 51 of the second embodiment will be described with reference to FIG. The tool holder 51 has a support shaft 3 integrated with the holder body 2, and a tool holding body 6 including a holding cylinder 9, a connecting cylinder 10 and a support cylinder 11 fitted in the support shaft 3, and an upper outer periphery of the support shaft 3 and the supporting shaft 3. In the support hole 11a of the support cylinder 11 having the axial length corresponding to the upper part of the shaft 3,
Similar to the first embodiment, the guide groove 12 is formed in each hole, and the ball 13 is interposed between the guide grooves 12.
4 are configured. A ball bearing 52 is interposed between the outer periphery of the lower portion of the support shaft 3 and the inner periphery of the holding cylinder 9. Since the support cylinder 11 that constitutes the tool holder 6 of the tool holder 51 has a shorter axial length than the support cylinder 11 of the tool holder 7 of the first embodiment, the mass of the tool holder 6 is relatively large. It is light. Therefore, the inertial force at the time of starting and stopping the spindle can be suppressed.

Although the pair of guide grooves 12 constituting the conversion mechanism 14 of the tool holder 51 are lead grooves,
Instead of the lead groove, a plurality of cam grooves may be provided along the locus of the lead groove to form a guide groove as a whole.

Next, a third embodiment will be described with reference to FIG. The tool holder 55 includes a holder body 2 having a holder cylinder 56, a support cylinder 11 and a support cylinder 58, and a tool holder 6 formed by integrally screwing a detection cylinder 59 around the lower outer circumference of the support shaft 3.
It consists of and. The holder cylinder 56 includes a tapered portion 56a formed on the upper portion and a grip portion 56 integrated with the tapered portion 56a.
b and a grip portion 56b, and a cylindrical portion 56c extending downward. The support cylinder 11 is fitted into the fitting hole 60 of the cylindrical portion 56c, and the outer circumference of the support cylinder 58 is integrally screwed into the fitting hole 60 from below to hold the holder. The body 2 is constructed. This support cylinder 11
The support shaft 3 upper part of the tool holder 6 is fitted into the support hole 11a of the support hole 11a, and in this fitted state, the support hole 11a and the support shaft 3
Similar to the first embodiment, the guide grooves 1 are formed on the upper outer circumference.
2 is provided, and a ball 13 is interposed between the guide grooves 12 to form a conversion mechanism 14. A ball bearing 52 is interposed between the inner circumference of the bearing shaft 58 and the outer circumference of the intermediate portion of the support shaft 3.

A central hole 62 opening to the fitting hole 60 is bored inside the tapered portion 56a of the holder body 2, and a cylindrical block 6 to be inserted into the central hole 62 is formed below the central hole 62.
3 is provided with a step portion 62a for locking the collar portion 63a, and a steel ball 66 is interposed between support holes 63b and 3a formed in the lower end surface of the cylindrical block 63 and the upper end surface of the support shaft 3, respectively. Further, the columnar block 63 is urged downward by a spring 67 to form a support mechanism 68. This support mechanism 68
The rotation of the holder body 2 is transmitted to the tool holding body 6 by the pressing force between the cylindrical block 63 and the steel ball 66 and the upper end surface of the support shaft 3 and the steel ball 66. Also, the compressive strength of the spring 67, which is subjected to overload thrust or torque generated on the tool, can be adjusted by removing the pull stud 69 and replacing the spring 67 with a spring having a different compressive strength.

The reference detector 24 and the tool holder 6 which are integrally screwed to the outer circumference of the holder cylinder 56 constituting the holder body 2.
Of the displacement detector 21 formed on the outer circumference of the detection cylinder 59 that constitutes the
The shape, configuration, etc. are the same as in the first embodiment. Further, the overload torque (or thrust load) discriminating means 40 and the like are also the first.
It is similar to the embodiment.

Next, the case where only the overload thrust load (the same applies when only the overload torque or the overload thrust load and the overload torque occur at the same time) is generated in the tool due to tool wear will be described. The rotation of the holder body 2 is transmitted to the tool holding body 6 by the support mechanism 68 until the overload thrust load exceeding the compressive strength of the spring 67 is generated in the tool during drilling. In addition, the support mechanism 68
As shown in FIG. 5, one side surface of the displacement detector 21 and one side surface 30a of the low step portion 30 of the reference detector 24 are brought into contact with each other by the conversion mechanism 14, and the output signal of the overload thrust load is output. Not done. When an overloaded thrust load is generated on the tool, in the support mechanism 68, the spring 67 moves rearward and the pressure contact between the steel ball 66 and the cylindrical block 63 causes slippage. Therefore, the tool holder 6 is retracted with respect to the holder body 2, and this axial movement is converted into circumferential rotation by the conversion mechanism 14, and the displacement detector 21 is opposite to the rotation direction with respect to the reference detector 24. Rotate in a predetermined direction (play a in the case of this embodiment). By this rotation, the detection area 28,
There is a difference in the number of pulses counted among the 29, so that the detection signal of the overload thrust load is output as an output signal.

Next, the tool holder 70 of the fourth embodiment will be described with reference to FIGS. 9, 10, 11 and 12.
The holder body 2 urges the tapered portion 71 formed on the upper portion, the grip portion 73 integrated with the tapered portion 71, the support shaft 74 axially slidably inserted in the center of the tapered portion 71, and the support shaft 74 downward. A thrust load setting spring 75 is provided. This spring 75 receives a thrust load generated in a tool such as a drill of the tool holder 6 described later, and does not bend backward in the axial direction until a certain set thrust load is exceeded. Support shaft 74
The front end surface of the support shaft 74 is formed as a conical surface 76 and
A sleeve 77 is loosely fitted in the sleeve 77, and the rear end surface of the sleeve 77 is formed as a conical surface 78. These conical surfaces 76, 78
Large and small pivot ball bearings 79 and 80 for supporting the bearings are fitted to the holding cylinder 81 of the tool holding body 6. The spacer 82 and the sleeve 7 mounted on the support shaft 74 so as not to move axially forward.
A spring 83 is interposed between the collar portion 77a of 7 and
With the spring force of this spring 83, the two conical surfaces 76, 7
A preload is applied to the pivot ball bearings 79, 80 via 8. This spring force is set so as to provide a preload that minimizes the friction torque generated by the pivot ball bearings 79 and 80. A collet chuck for holding a tool is attached to the front end of the holding cylinder 81. A deep groove ball bearing may be used instead of the pivot ball bearing.

A connecting cylinder 84 is integrally screwed to the outer periphery of the holding cylinder 81, one end of a torsion coil spring 85 for torque transmission is connected to the connecting cylinder 84, and the other end of the spring is the grip portion 7.
It is connected to 3. Two upper and lower positioning pins 86 are implanted in the connecting cylinder 84, and a detection ring 88 having a large number of locking holes 87 that engages and disengages the positioning pins 86 is interposed between the holding ring 73 and a spring 89. Is biased forward by. Therefore, the torsional strength of the torsion coil spring 85 is such that the detection ring 88 is moved upward against the spring force to move the locking hole 87.
And the positioning pin 86 are disengaged, and in this state the holding cylinder 8
After rotating 1 and the connecting cylinder 84 in the circumferential direction, the detection ring 8
It is adjusted by engaging the locking hole 87 of No. 8 and the positioning pin 86.

The upper part of the detection ring 88 is formed into two large and small cylindrical portions 90 and 91, and both cylindrical portions 90 and 91 are shown in FIG.
As shown in FIG. 0, a plurality of recesses 92 and 93 (three in this figure) are respectively cut, and the spaces between them are equiangularly spaced in the circumferential direction (angle θ (120 degrees in FIGS. 11 and 12). ) Oki)
Are formed on the three displacement detectors 94 and the displacement converter 95. In the three concave portions 92 of the large-diameter tubular portion 90, the grip portion 7
Three to three reference detectors 96 are bored, and the small diameter tubular portion 91
In the three concave portions 93, three reference converters 97 project from the grip portion 73. As shown in FIG. 11, the rotational edges of the displacement detector 93 and the reference detector 96 are a pair of detection display portions 98 indicating the detection start or the detection end by the proximity switch 35 similar to the first embodiment. , 97 and the detection display section 101, 98 between the pair of rotation deviation detection areas 1
02, 103 are formed, and such detection areas 102, 1
03 are provided in three pairs in the circumferential direction. When the detection areas 102 and 103 are detected, the proximity switch 35 is turned off.

In FIG. 12, an inclined surface 105 that engages with the inclined surface 104 provided on one side of the displacement transducer 95 is formed on one side surface of the reference transducer 97, and the torsion force of the torsion coil spring 85 is formed. A conversion mechanism 1 for converting the axial movement of the tool holder 6 into a circumferential rotation when an overload thrust load is generated on the tool by bringing the inclined surfaces 104 and 105 into contact with each other.
06 is configured. Further, when both the inclined surfaces 104 and 105 are in contact with each other, a slight circumferential play (FIG. 11) is formed between the other side surface of the reference transducer 97 and one side surface of the displacement transducer 95 adjacent in the rotation direction. , A) of FIG. 12 is provided. The circumferential lengths L of the pair of detection areas 102 and 103, the reference detector 96, the displacement detector 94, and the displacement converter 95 are all set to the same (30 degrees), and the large and small tubular portions 90, The circumferential length 3L of each of the concave portions 92 and 93 of 91 and the reference transducer 97 are set to the same (90 degrees). The overload thrust load (or overload torque) discriminating means 40 is the same as that in the first embodiment.

Next, the case where only the overload thrust load is generated in the tool due to the tool wear will be described. The rotation of the holder body 2 is transmitted to the tool holding body 6 by the torsion coil spring 85 until the overload thrust load exceeding the set thrust load of the spring 75 is applied to the tool during the cutting work. Further, during the normal processing, the torsion coil spring 85 causes the displacement transducer 95 and the reference transducer 97 to move.
Since the respective inclined surfaces 104 and 105 are in contact with each other, the output signal of the overload thrust load is not output. When an overloaded thrust load is generated on the tool, the spring 75 bends rearward, the tool holder 6 retracts with respect to the holder 2, and the displacement transducer 95 becomes the reference transducer 97 due to the engagement between the inclined surface 104 and the inclined surface 105. A predetermined angle (play a) is rotated in the opposite direction to the rotation direction. Due to this rotation, the displacement detector 94 becomes rotationally delayed with respect to the reference detector 96 (play a in the circumferential direction),
Since there is a difference in the number of pulses counted between the detection areas 102 and 103, the detection signal of the overload thrust load is output as an output signal.

In the tool holder 70, the displacement detector 94 and the reference detector 96 provided on the outer periphery of the tool holder 70 are sufficiently spaced in the circumferential direction, and like the tool holder 7 of the first embodiment. One side of the displacement detector 21 is the displacement detector 2
Since one side face of the reference detector 24 is not abutted by the rotation in the circumferential direction of the predetermined amount 1 (play a), the detector 9
At the time of the relative circumferential rotation between 4, 96, this circumferential rotation is performed without being externally affected by cutting fluid, dust and the like.

A fifth embodiment will be described with reference to FIGS. In the tool holder 200, the holder body 2 has a cylindrical portion 201 projecting forward from the grip portion 2b.
A support shaft 203 of the tool holder 6 is rotatably supported via a ball bearing 204 in a support hole 202 formed at the center of the tubular portion 201. A pressure contact block 206 is fitted in a center hole 205 in the holder body 2 continuous with the support hole 202 so as to be movable in the axial direction, and a compression spring 208 is provided between the pressure contact block 206 and a pull stud 207 screwed to the rear end of the holder body 2 . The press contact block 206 biases the support shaft 203 forward through the steel balls 209, and the pressing force of the steel balls 209 transmits the rotation of the holder body 2 to the tool holding body 6. The spring force of the compression spring 208 is set so as to correspond to both the thrust load and the torque applied to the tool 4 and less than the smaller one of the maximum allowable thrust load and the maximum allowable torque.

At the rear end of the support shaft 203, cam grooves 211 are cut left and right as shown in FIG. Cam groove 211
As shown in FIG. 16, the shape of is formed so as to have a downward slope toward the rear in the axial direction. Further, guide pins 210 are respectively implanted in the cylindrical portion 201 of the holder body 2 at positions facing the cam grooves 211, and the inner ends of the guide pins 210 are slidably fitted into the cam grooves 211. . Therefore, when the guide pin 210 is moved backward by the cam groove 211 in the axial direction of the tool holder 6, the guide pin 2
A conversion mechanism 214 in which the cam groove 211 is guided by 10 and the tool holder 6 moves in the circumferential direction is configured.

Next, displacement detectors 216 are provided on the outer periphery of the rear end of the detection cylinder 215 which constitutes the tool holder 6 together with the support shaft 203 at 120 degree intervals in the circumferential direction. In addition, reference detectors 217 are provided so as to protrude between the displacement detectors 216 from the gripping portion 2b of the holder body 2 at 120 ° intervals in the circumferential direction. The reference detector 217 includes a low step portion 217a and a protruding portion 217b, and the low step portion 217a and the protruding portion 217 are provided.
The circumferential lengths of b and the displacement detector 216 are set to 30 degrees, respectively. Then, in the state where there is no overload thrust load or overload torque, the detection cylinder 215 is biased by the spring force of the compression spring 208 in the Z direction (same as the rotation direction) of FIG. 15 via the conversion mechanism 214. So the lower part 217
The state in which a and the displacement detector 216 are in contact with each other is maintained. Further, the position of the guide pin 210 at this time is the solid line position shown in FIG. 16 with respect to the cam groove 211.

In the tool holder 200, the displacement detector 216 and the reference detector 217 have the relationship shown in FIG. 15 until the overload thrust load and / or the overload torque is applied to the tool 4 by the spring force of the compression spring 208. Rotate while keeping,
To process. In this state, for example, the distance between the proximity switch 35 being turned on in the detection display portion 216c of the displacement detector 216 and being turned on again in the detection display portion 217c of the next reference detector 217 is constant at 60 degrees, No overload signal is output. However, when the overload thrust load is applied to the tool 4, the steel ball 209 compresses the compression spring 208 via the pressure contact block 206, the tool holder 6 retracts, and the conversion mechanism 2
The guide groove 211 is guided along the guide pin 210 by 14 and the displacement detector 216 retracts and rotates in the direction opposite to the Z direction. At this time, a slip occurs between the steel ball 209 and the pressure contact block 206. When the displacement detector 216 rotates in this way, the interval between the detection display portions 216c and 217c changes, so this change in interval is captured and compared with the steady-state value (60 degrees above) and set in advance. Outputs an overload signal when the value exceeds a certain allowable value. Further, when the overload torque is generated, the tool holder 6 rotates relative to the holder body 2, so that the displacement detector 216 causes the conversion mechanism 214 to move.
It will retreat while rotating through. In the present embodiment, the pressure contact block 206 and the steel ball 209 are eliminated,
A torsion coil spring for torque transmission may be interposed between the rear end of the support shaft 203 and the pull stud 207.

Next, still another embodiment will be described with reference to FIG.
In FIG. 17, a guide pin 221 is planted in a tool holder 6 that is rotatably supported by a support shaft 220 that projects forward from the center of the holder body 2, and the support shaft 2 that faces the guide pin 221.
A conversion mechanism 223 is formed by forming a cam groove 222 on the outer circumference of 20. The tool holder 6 is biased forward through a compression spring 208, a sliding pin 224 and a steel ball 225. A detection ring 226 is integrally fixed to the rear end of the tool holder 6, and the displacement detector 21 formed on the detection ring 226 is formed.
6 and the reference detector 217 of the holder body 6 are the same as those in FIG.

[0037]

As described above, in the tool holder of the present invention, the detector having the conversion mechanism utilizing the inclined surface on the outer circumference is used.
Since it is installed closer to the rotation center of the tool holder,
A circle at the position of the conversion mechanism depending on the axial movement of the tool holder
The amount of movement in the circumferential direction is expanded at the detector position on the outer circumference of the holder.
The amount of movement in the circumferential direction can be made small, and the amount of movement in the axial direction of the tool holder for obtaining at least a predetermined amount of rotation of the detector capable of detecting the overload thrust load can be made extremely small. Therefore, even if the tool holder is a tool holder in which the tool holder moves axially in order to detect the thrust load, the influence of the axial movement amount on the machining hole depth can be reduced.

[Brief description of drawings]

FIG. 1 is a front view of a tool holder according to a first embodiment.

FIG. 2 is an enlarged cross-sectional view of the tool holder according to the first embodiment.

3 is a sectional view taken along line III-III in FIG.

4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a development view of the displacement detector and the reference detector of the tool holder of the first embodiment in the entire circumference in the circumferential direction.

FIG. 6 is a block diagram of a control device.

FIG. 7 is a sectional view of a second embodiment.

FIG. 8 is a sectional view of a third embodiment.

FIG. 9 is a sectional view of a tool holder according to a fourth embodiment.

10 is a sectional view taken along line XX of FIG.

FIG. 11 is a development view of the displacement detector and the reference detector of the tool holder of the fourth embodiment in the entire circumference in the circumferential direction.

FIG. 12 is a development view of the displacement converter and the reference converter of the tool holder of the fourth embodiment in the entire circumference in the circumferential direction.

FIG. 13 is a sectional view of a fifth embodiment.

14 is a sectional view taken along line XIV-XIV in FIG.

FIG. 15 is a development view of the displacement detector and the reference detector of the tool holder of the fifth embodiment in the entire circumference in the circumferential direction.

FIG. 16 is an explanatory diagram of a conversion mechanism of the fifth embodiment.

FIG. 17 is a modification of the fifth embodiment.

[Explanation of symbols]

2 holder body, 3 support shaft, 6 tool holder, 7,
51, 55, 70, 200 Tool holder, 11a Support hole, 12 guide groove, 13 ball, 14, 10
6,214 conversion mechanism 21,24,94,96,21
6,217 detector, 104, 105 inclined surface, a
Misalignment

Claims (3)

[Claims] 1. A tool holder is supported on a holder body so as to be movable in a circumferential direction and an axial direction, respectively, and the outer circumference of the holder body and the tool holder are supported.
A plurality of detectors are arranged on the outer circumference of the body at a predetermined pitch in the circumferential direction.
The tool holder and the detector of the tool holder facing each other.
There is an overload between the holder body and tool holder.
With a spring, and circular movement of the tool holder in the axial direction.
A conversion mechanism that uses an inclined surface that converts to circumferential rotation
Provided at a position closer to the rotation center of the tool holder than the sensor,
The holder body of the tool holder generated by the overload thrust is
The axial movement of the tool holder
Converted to circumferential rotation, and work on the detector on the holder side.
Extracted as a change in the circumferential position of the detector on the tool holder side
Tool holder characterized by being made possible . 2. A support shaft outer circumference projecting from the center of one of the holder body and the tool holding body toward the other member and a support hole inner circumference of the other member fitted into the support shaft, respectively. The tool holder according to claim 1, wherein a guide groove inclined with respect to the rotation axis of the tool holder is provided, and a ball is interposed between the guide grooves to configure the conversion mechanism. 3. A cam shaft, which is inclined with respect to the rotation axis of the tool holder, is provided on a support shaft projecting from the center of one of the holder body and the tool holder toward the other member. The tool holder according to claim 1, wherein the conversion mechanism is configured by slidably fitting a guide pin integrally provided with the other member.