JPH05200651A - Tool holder - Google Patents

Abstract

PURPOSE:To reduce the of springs for setting the extent of cutting load, in a tool holder which detects a fact that the cutting load has become too much. CONSTITUTION:A guide pin 210 as one body with a holder body 2 is fitted in a cam groove 211 formed in a shaft 203 of a tool holder 6, converting a traveling direction of the tool holder 6 to the holder body 2 into two ways at an interval between axial backward net and circumferential movement reverse to the direction of rotation. In addition, it is set down to a conversion mechanism 214 converting the traveling direction into two ways at an interval between axial forward movement and the circumferential movement in the same direction as the direction of rotation of the tool holder 6 to the holder body 2, and the tool holder 6 is energized to the holder body 2 in the axial front and the same direction as the direction of rotation by dint of spring force of a compression spring 208.

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 cutting chips are not properly discharged during cutting with a drill, the cutting torque will increase and the drill will break, or if the drill is worn and processed with constant feed, an excessive thrust force will be generated. , This sometimes caused the drill to buckle.

As a tool holder for detecting the above-mentioned excessive torque and thrust load, 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 and axial directions respectively, 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 placed between each other. The detector shaft is contacted by the torsional force of the torsion coil spring for setting the transmission torque that connects the holder shaft and the tool holding cylinder, and the contact surface is inclined at a large angle to the axial direction. Is provided to convert the axial movement of the tool holding cylinder into a circumferential rotation by engaging the inclined surfaces with each other, so that not only the overload torque but also the overload thrust load can be controlled by a predetermined amount of the tool holding cylinder and the holder shaft. It is taken out as a rotation deviation .

[0004]

In the prior art, two springs, a thrust load setting spring and a torsion coil spring for setting transmission torque, are interposed between the tool holding cylinder and the holder shaft. It takes time and effort to adjust and manage the springs separately, and there is also a problem that the number of parts increases.

[0005]

In order to solve the above problems, the present invention supports a tool holder on a holder body so as to be movable in a circumferential direction and an axial direction, respectively, and cuts between the holder body and the tool holder. A load setting spring is interposed to urge the tool holder to the holder body axially forward and in the rotational direction, and the cutting load generated on the tool holder during cutting is larger than the set load of the spring. A tool holder configured to detect relative movement of the tool holder with respect to the holder body when
A conversion mechanism that performs bidirectional conversion between the axial movement of the tool holder relative to the holder body and the movement in the rotational direction of the holder body between the holder body and the tool holder, and a bidirectional conversion in which the movement direction is opposite to the above. It is characterized by interposing.

[0006]

In the tool holder of the present invention, when a spring for biasing the tool holder forward with respect to the holder body is interposed between the tool holder and the holder body, the tool holder is rotated in the rotational direction with respect to the holder body by the conversion mechanism. Is biased in the same direction as
Thrust load and transmission torque can be set with one. Further, this spring may be a torsion coil spring for urging the tool holding body in the rotational direction with respect to the holder body, and this circumferential urging force causes the conversion mechanism to move the tool holding body forward in the axial direction with respect to the holder body. After all, the thrust load and the transmission torque are set by this one torsion coil spring.

[0007]

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 inserting the support cylinder 11 into the hollow formed by both members is fitted. In this fitted state, the support shaft 11
A guide groove (lead groove) 12 that is inclined with respect to the rotation axis of the tool holder 7 is 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. With the ball 13 interposed, the tool holder 6 is bidirectionally moved between the axial movement of the tool holder 6 relative to the holder 2 (movement in the direction approaching the spindle 1) and the circumferential movement of the tool holder 7 in the opposite direction to the rotational direction. The movement direction is changed, and both the axial forward movement of the tool holder 6 with respect to the holder body 2 (movement in the direction away from the spindle 1) and the circumferential movement in the same direction as the rotational direction of the tool holder 7 are performed. A conversion mechanism 14 for converting the moving direction to the direction is 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.

One end of a torsion coil spring 16 for setting a cutting load is connected to the connecting cylinder 10 of the tool holder 6.
The other end of the spring 16 is connected to the grip portion 2b of the holder body 2,
The rotation of the holder body 2 is transmitted to the tool holder 6 during processing. In addition, as shown in FIG. 3, the connecting cylinder 10 has a spring 20 in which a detection ring 19 in which a large number of locking holes 17 and two left and right pins 18 that engage and disengage are planted is interposed between the connecting ring 10 and the grip portion 2b. The detection ring 19 is integrally attached to the connecting cylinder 10 by being urged downward by. Therefore, torsion coil spring 1
The torsional strength of 6 moves the detection ring 19 backward (upward in FIG. 2) against the spring force to release the engagement between the locking hole 17 and the positioning pin 18, and in this state, the connecting cylinder 10 is rotated circumferentially. After rotating in the direction, adjustment is made by engaging the locking hole 17 of the detection ring 19 and the positioning pin 18. Further, 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, and is set so as to correspond to the smaller one of the maximum allowable thrust load and the maximum allowable torque. The tool holder 6 is urged by the coil spring 16 in the rotation direction (the arrow direction in FIG. 5) with respect to the holder body 2, and is also urged axially forward by the conversion mechanism 14 to form a torsion coil. Both the torque and the thrust are loaded by the spring 16.

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 rotational direction of the tool holder that indicate the start or end of detection by a proximity switch 35, which will be 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 a center protruding, and both edges of the center protruding portion 25 in the rotation direction indicate a detection start or a detection end by a 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 within 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
The proximity switch 35 is turned off when is detected. 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 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 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 per revolution 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
5 is a counter for adding or subtracting the spindle angle pulse Ps input while the gate circuit 44 is open,
Reference numeral 46 switches an addition or subtraction command to the counter 45 in one cycle of the ON / OFF signal of the proximity switch 35, and outputs a judgment 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. 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 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-mentioned 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. In the detection range 28, the gate circuit 44 is turned off, and during this period, 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 protrusion 25. ON
Then, the gate circuit 44 is closed and switched to subtraction. When the proximity switch 35 detects the detection area 29 again and is turned 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 make 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 areas 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 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 overload 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 in the direction opposite to the rotation 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 detection area 28 is added and the detection area 29 is added.
The result of the subtraction at −2a is −2a, and the absolute value 2a is 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 a predetermined number of times. When exceeding, the tool is replaced with a new tool that is the same as the tool even during machining.

When only the overload torque is generated, the tool holder 6 causes a rotation delay (circular rotation in the direction opposite to the rotation direction) with respect to the holder body 2. This is the same as the case where the holding body 6 is moved backward in the axial direction with respect to the holder body 2 and, as a result, only the axial thrust load is generated. Even if both the overload torque and the overload thrust occur in the same way, the same operation is performed.

Next, a second 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 below the grip portion 56b. The support cylinder 11 is fitted into the fitting hole 60 of the cylindrical portion 56c. 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
As in the first embodiment, the guide grooves 1 are formed on the outer periphery of the upper part, respectively.
2 is engraved, 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 inserted into the central hole 62 is formed below the central hole 62.
3 is provided with a stepped portion 62a for locking the flange portion 63a, and a steel ball 66 is interposed between the 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 holder 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. The compressive strength of the spring 67 that receives the cutting load generated in the tool can be adjusted by removing the pull stud 69 and replacing the spring 67 with a spring having a different compressive strength.

A reference detector 24 and a tool holder 6 which are integrally screwed to the outer circumference of a holder cylinder 56 which constitutes 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, a case will be described in which only the overload thrust load (the same applies when only the overload torque or the overload thrust and the overload torque occur at the same time) is caused by the tool wear. 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. Further, as shown in FIG. 5, one side surface 3 of the displacement detector 21 and one side surface 3 of the low step portion 30 of the reference detector 24 are supported by the support mechanism 68 and the conversion mechanism 14.
0a comes into contact with each other, and the output signal of the overload thrust load is not output. 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 a slip. Therefore, the tool holder 6 retracts with respect to the holder body 2, this axial movement is converted into a circumferential rotation by the conversion mechanism 14, and the displacement detector 21 becomes the reference detector 2.
4 is rotated in a direction opposite to the rotation direction by a predetermined angle (play a in this embodiment). By this rotation, the detection areas 28, 2
Since there is a difference in the number of pulses counted among the nine, the detection signal of the overload thrust load is output as an output signal.

Further, a third 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 supported via a ball bearing 204 in a support hole 202 formed at the center of the cylindrical portion 201 so as to be movable in the axial direction and the circumferential direction. The pressure contact block 20 is attached to the center hole 205 in the holder body 2 which is continuous with the support hole 202.
6 is movably mounted in the axial direction, a compression spring 208 for setting a cutting load is interposed between the stud 207 and a pull stud 207 screwed to the rear end of the holder body 2, and the pressure contact block 206 is attached to the steel ball 2.
The support shaft 203 is urged forward via 09 to move the steel ball 2
The rotation of the holder body 2 is transmitted to the tool holding body 6 by the pressing force of 09. The spring force of the compression spring 208 is
It is set so as to correspond to both the thrust load and the torque applied to the tool 4 in correspondence with the smaller value of the maximum allowable thrust load and the maximum allowable torque, and both torque and thrust are set by one compression spring 208. It is designed to load.

At the rear end of the support shaft 203, cam grooves 211 are cut left and right as shown in FIG. As shown in FIG. 11, the shape of the cam groove 211 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, the guide pin 210 and the cam groove 211 allow the tool holder 6 to move backward relative to the holder body 2 in the axial direction (to move toward the spindle 1) and to move the tool holder 200 in the circumferential direction opposite to the rotational direction. The direction of movement in both directions, and the direction of movement in both directions between the axial forward movement of the tool holder 6 with respect to the holder body 2 and the circumferential movement in the same direction as the rotation direction of the tool holder 200. A conversion mechanism 214 for converting the tool holder 6 is urged by the spring force of the compression spring 208 toward the holder body 2 in the axial forward direction and in the same rotational direction.

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 intervals of 120 degrees in the circumferential direction. Further, reference detectors 217 are provided so as to protrude between the displacement detectors 216 from the grip 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 urged by the spring force of the compression spring 208 via the conversion mechanism 214 in the Z direction of FIG. 15 (the same as the rotation direction). So the lower part 217
The state where a and the displacement detector 216 are in contact with each other is maintained. The position of the guide pin 210 at this time is the solid line position shown in FIG. 11 with respect to the cam groove 211.

In this tool holder 200, the displacement detector 216 and the reference detector 217 have the relationship shown in FIG. 10 by the spring force of the compression spring 208 until an overload thrust load and / or an overload torque is applied to the tool 4. Rotate while keeping,
To process. In this state, for example, the distance between the proximity switch 35 being turned on in the detection display section 216c of the displacement detector 216 and being turned on again in the detection display section 217c of the next reference detector 217 is constant at 60 degrees, No overload signal is output. However, when an 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, slippage occurs between the steel ball 209 and the press contact block 206. When the displacement detector 216 rotates in this way, the interval between the detection display units 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. The overload may be detected by detecting the backward movement of the tool holder with respect to the holder as is well known in Japanese Patent Publication No. 51-15630.

[0025]

As described above, according to the present invention, between the tool holder and the holder body, bidirectional conversion between the axial forward movement of the tool holder with respect to the holder body and the rotation direction of the holder body,
Since a conversion mechanism that performs bidirectional conversion in which the movement direction is reversed is interposed, a spring for setting the cutting load is a spring that biases the tool holder forward with respect to the holder body, or a rotation direction. If either one of the springs biasing in the same direction is adopted, both the values of torque and thrust can be set by this spring, and there is an advantage that the number of cutting load setting springs can be set to one.

[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.

9 is a sectional view taken along line IX-IX in FIG.

FIG. 10 is a development view of the displacement detector and the reference detector of the tool holder of the third embodiment in the entire circumference in the circumferential direction.

FIG. 11 is an explanatory diagram of a conversion mechanism of the third embodiment.

[Explanation of symbols]

2 holder body, 3 support shaft, 6 tool holder, 7,
55,200 Tool holder, 11a Support hole, 12
Guide groove, 13 balls, 14,214 Conversion mechanism 21, 24, 216, 217 Detector

Claims (1)

[Claims] 1. A holder supporting a tool holder movably in a circumferential direction and an axial direction respectively, and a spring for setting a cutting load is interposed between the holder and the tool holder with respect to the holder. Detects the relative movement of the tool holder with respect to the holder body when the cutting load generated on the tool holder during cutting exceeds the set load of the spring by urging the tool holder axially forward and in the rotational direction. In the tool holder configured as described above, bidirectional conversion between the axial forward movement of the tool holder relative to the holder body and the rotational direction movement of the holder body between the holder body and the tool holder, and the movement direction are as described above. A tool holder characterized by interposing a conversion mechanism for performing bidirectional conversion which is the reverse of the above.