JPH071291A - Tool holder - Google Patents

Abstract

PURPOSE:To shorten the overall length of a tool holder, to reduce size and weight, and to improve rigidity by a method wherein a bearing to rotatably support a tool holding cylinder on a holder shaft, a twist coil spring for transmission of torque or one spring to receive torque and thrust are disposed such that the positions in the direction of an axis thereof are overlapped with each other. CONSTITUTION:A twist coil spring 18 is disposed in a state that the position in an axial direction of a part thereof is overlapped with that of a bearing outside a roller bearing 15 in a manner to surround the outside of the bearing 15 therewith. In ordinary cutting work, the slope surfaces 38 and 41 of a displacement detecting element 25 and a detecting element 31 are kept in a contact state by means of the twist force of the twist coil spring 18. With this state, a slight peripheral play alpha is provided between the other surface of the low stage part 37 of the detecting lement 31, and a detecting display part 28 positioned facing the surface. The lengths in a peripheral direction of a pair of detecting areas 35 and 36, a reference detecting element 32, and a displacement detecting element 25 are entirely the same as each other (approximate 30 deg.). There is no difference between a time in which the detecting area 35 is detected by an approach switch and the switch is turned OFF and a time in which the detecting area 36 is detected and the switch is turned OFF, and it is not decided that an overload is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present application relates to a tool holder for mounting a tool such as a drill or a tap on a spindle of a machine tool.

[0002]

2. Description of the Related Art As a conventional tool holder, there is one disclosed in Japanese Patent Laid-Open No. 3-245950 by the present applicant, which is capable of rotating a tool holding cylinder with respect to a holder shaft and axially moving it. Supporting, connecting the holder shaft and the tool holding cylinder with a torsion coil spring that transmits the rotation of the holder shaft to the tool holding cylinder, and providing a thrust spring for urging the tool holding cylinder forward with respect to the holder shaft, Furthermore, a conversion mechanism (slope) that converts the axial movement of the tool holding cylinder into a circumferential movement is provided, and the overload torque and / or the overload thrust applied to the tool at the tip of the tool holding cylinder during cutting is held by the holder shaft of the tool holding cylinder. Was detected as a rotational deviation with respect to the tool cutting loss prediction.

[0003]

In the conventional tool holder described above, the pivot ball bearings that rotatably support the tool holding cylinder with respect to the holder shaft are arranged side by side without overlapping the axial position of the torsion coil spring. Therefore, the overall length of the tool holder is relatively long, the rigidity of the holder is low, and the deflection accuracy of the tool holding portion is poor. Further, when a carbide drill or a small-diameter drill, which is particularly weak in bending, is used for this holder, there is a fear that fatigue fracture due to bending may occur.

[0004]

In order to solve the above-mentioned problems, in the present application, a tool holding cylinder is rotatably and axially movably supported with respect to a holder shaft, and between the holder shaft and the tool holding cylinder. In a tool holder in which a torsion coil spring for torque transmission or one spring for receiving both torque and thrust is interposed in the tool holder, an axis line of a bearing for rotatably supporting a tool holding cylinder with respect to a holder shaft and the spring. It is characterized in that the directional positions are overlapped.

[0005]

The overlap of the bearing and the torsion coil spring in the axial direction makes it possible to shorten the overall length of the tool holder and improve the deflection accuracy of the tool holder. Further, even when using a cemented carbide drill or a small diameter drill, fatigue fracture due to bending can be prevented. Further, the tool holder becomes small and lightweight.

[0006]

Embodiments of the tool holder 1 of the present application will be described below with reference to the drawings. The holder shaft 2 is configured by screwing a holder shaft side detection ring 4 to a holder body 3 formed in a tapered shank. A thrust force transmission pin 6 is axially movably fitted in a support cylinder portion 5 projecting forward from the center of the holder body 3, and the thrust force transmission pin 6 is inserted into a mounting hole 7 of the holder body 3. It is biased forward by the thrust spring 8 provided. The thrust spring 8 receives a thrust load applied to a tool 12 held by a tool holding cylinder 11 described later, and the set value of the spring force is an overloaded thrust load corresponding to the tool used,
It does not bend in the axial direction until the set load is exceeded.

Next, the tool holding cylinder 11 is constructed by screwing the flange portion 14a of the support sleeve 14 to the rear end of the collet chuck portion 13 for holding the tool 12. A rolling bearing 15 is interposed between the inner peripheral surface of the support sleeve 14 and the outer peripheral surface of the support cylindrical portion 5, and the tool holding cylinder 11 is supported rotatably and axially movable with respect to the holder shaft 2. There is. In addition, this rolling bearing 15 has a large number of balls 1.
6 is a well-known one in which a holder 17 having high rigidity is rotatably held and arranged in a spiral shape. Further, the flange portion 14a of the support sleeve 14 and the holder shaft side detection ring 4 are connected by a torsion coil spring 18 that transmits the rotation of the holder shaft 2 to the tool holding cylinder 11, and the tool holding cylinder 11 is connected to the holder shaft 2. The tool holder 1 is biased in the same direction (arrow Z in FIG. 2) as the rotation direction. The torsion coil spring 18 is arranged so that a part of the torsion coil spring 18 surrounds the outside of the rolling bearing 15, that is, a part of the torsion coil spring 18 overlaps the axial direction position outside the rolling bearing 15. The overall length is short, and it is compact and lightweight. The flange portion 14a of the support sleeve 14 has a pair of upper and lower positioning pins 21 extending rearward.
Have been planted (shown in Figure 3). The pair of positioning pins 21 are locking holes 23 formed in the inner flange portion 22a of the holding cylinder side detection ring 22 in a large number at regular intervals in the circumferential direction.
Two of them are locked in the locking holes 23. The detection ring 22 is supported by the outer peripheral surface of the flange portion 14a and the inner peripheral surface of the holder-side detection ring 4, is rotatable in the circumferential direction, and is movable in the axial direction by a predetermined amount. Is urged forward by a detection ring urging spring 24 interposed between the holder shaft side detection ring 4 front surface. Therefore, the torsional strength of the torsion coil spring 18 is such that the detection ring 22 is moved backward (to the right in FIG. 2) against the spring force and the locking hole 23 of the detection ring 22 and the positioning pin 21 of the support sleeve 14 are moved. Is disengaged, and in that state, the tool holding cylinder 11 is rotated with respect to the holder shaft 2 in the circumferential direction, and then the positioning pin 21 is engaged with the other locking hole 23 so as to be adjustable. , The overload torque load corresponding to the tool 12 used is set.

As shown in FIG. 4, a plurality of displacement detectors 25 (3 in this figure) are provided at the rear end of the detection ring 22 on the side of the holding cylinder.
Are provided at equal pitches in the circumferential direction (at intervals of 120 degrees). Both edges of the displacement detector 25 in the circumferential direction serve as detection display portions 27 and 28 indicating the start or end of detection by the proximity switch 42 described later. Further, at the front end of the holder shaft side detection ring 4, a plurality of convex detection pieces 31 (3
Are formed at equal pitches (at intervals of 120 degrees) in the circumferential direction. As shown in FIG. 4, each of the convex detection pieces 31 has a stepped shape with the center protruding, and the protruding portion at the center is a reference detector 32, and both edges in the circumferential direction of the reference detector 32 are close to each other as described later. A pair of detection display portions 33 and 34 are provided to indicate the start or end of detection by the switch 42. A pair of detection regions 35 and 36 for rotational displacement are formed between the pair of detection display units 27 and 28 and the pair of detection display units 33 and 34 in the circumferential direction of 120 degrees, and the entire circumference in the circumferential direction. Then, three pairs of such detection areas 35 and 36 are provided, and when these detection areas 35 and 36 are detected, the proximity switch 42 is turned off.
Becomes An inclined surface 41 that engages with an inclined surface 38 formed on one side of the displacement detector 25 is provided on one side surface of the low step portion 37 of each convex detection piece 31, and an overload occurs due to the engagement of both inclined surfaces 38, 41. When the displacement detector 25 moves rearward in the axial direction due to the thrust load, this is converted into rotation of the displacement detector 25. In addition, as shown in FIG.
Is attached to the front surface of the spindle head 43 via a bracket 44.

Next, the tool holder 1 configured as described above
The action of will be described. During normal cutting (less than or equal to overload thrust and overload torque), the two inclined surfaces 38 and 41 are in contact with each other due to the torsional force of the torsion coil spring 18, and in this state, the other side surface of the low step portion 37, There is a slight play α in the circumferential direction between the detection display unit 28 facing this surface, and the circumferential lengths of the pair of detection regions 35 and 36, the reference detector 32, and the displacement detector 25. All are the same (30 degrees), and there is no difference between the time when the proximity switch 42 detects the detection area 35 and is OFF and the time when the proximity switch 42 detects the detection area 36 and is OFF, and it is determined to be an overload. Not done. On the other hand, when the load is equal to or more than the overload thrust load or the overload torque load, the reference detector 32 and the displacement detector 25 are displaced in the circumferential direction (shown by the phantom line in FIG. 4), and the detection area 35 is
Degree + α, and the detection area 36 becomes 30 degrees -α, which causes a difference in the OFF time in the detection areas 35 and 36, which causes the not-shown discriminating means to discriminate the overload and determine the spindle motor. An overload signal is output,
Performs step back operation or cancels machining.

In the above embodiment, the rolling bearing 15 is exemplified as the bearing, but the bearing is not limited to this and may be a needle roller bearing or a ball bearing.

Next, the tool holder of the second embodiment will be described with reference to FIGS. 5 and 6, but the description of the same construction as that of the above embodiment, such as the method of attaching the holding cylinder side detection ring 22, will be omitted. A support shaft 4 extending forward in the center of the holder body 3
7, a support cylinder 48 is fitted on the support shaft 47, and the support cylinder 48 is integrally fitted to a tool holding cylinder 11 formed by screwing the collet chuck portion 13 and the support sleeve 14. There is. Outer periphery of the support shaft 47 and the support cylinder 4
8. On the inner peripheral surface, spiral guide grooves 49 facing each other and inclined with respect to the rotation axis of the tool holder 1 are engraved, balls 50 are interposed between the guide grooves 49, and at least the tool is overloaded with thrust. A conversion mechanism 51 is configured to convert the axial movement of the tool holding cylinder 11 into a circumferential rotation when a load is applied. Reference numeral 52 is a return tube provided inside the support cylinder 48 for circulating the balls 50. The conversion mechanism 51 has a ball screw structure, and the balls 50 are in rolling contact with the support shaft 47 and the support cylinder 48 so that the frictional force is small and also the role of the rolling bearing 15 of the above-described embodiment is fulfilled.

Between the support sleeve 14 of the tool holding cylinder 11 and the holder shaft 2, the rotation of the holder shaft 2 is transmitted to the tool holding cylinder 11, and both the thrust load and the torque applied to the tool during cutting are received. Two torsion coil springs 53 (springs) are interposed. The arrangement position of the torsion coil spring 53 is such that the tool holding cylinder 1 is attached to the holder shaft 2.
A conversion mechanism 5 serving as a bearing for rotatably supporting 1
The tool holder 1 as a whole is designed to have a short overall length. As shown in FIG. 6, the detector 25 of the holding cylinder side detection ring 22 and the low step portion 37 of the holder shaft side detection ring 4 are not formed with the slopes 38 and 41 as in the first embodiment. , Detector 25
Is engaged with one side surface of the low step portion 37 of the holder shaft side detection ring 4, and detection areas 35 and 36 similar to the above are formed. A compression spring may be used instead of the torsion coil spring in this second embodiment.

Next, another embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the same parts as those in the above-mentioned embodiment are designated by the same reference numerals and the description thereof will be omitted. This embodiment is a tool holder 1 attached to a spindle of a so-called dedicated processing machine. Once mounted on the spindle 70, the tool holder 1 at the tip of the quick change holder 80 does not have to be detached from the spindle 70 when the tool is replaced. By exchanging the adapter 87, the tool is exchanged. That is, the straight shank 72 of the holder body 3 of the tool holder 1 is fitted into the straight mounting hole 71 of the spindle 70,
The key 73 is fixed and fixed with a screw 74. The holder body 3 has a cylindrical shaft 75 extending forward, and the holder shaft side detection ring 4 is integrally screwed. The tool holding cylinder 11 has a holding cylinder main body 7 having a support shaft 76 which is rotatably and axially movably supported on the inner circumference of the cylindrical shaft 75.
7, a holding cylinder side detection ring 22, and a quick change holder 80 provided at the tip of the holding cylinder body 77. A stepped bolt 76a is screwed to the rear end of the support shaft 76, and the thrust spring 8 biases the support shaft 76, that is, the holding cylinder main body 77 forward through the pressing plate 76b and the ball 76c. . The shapes of the displacement detector 25 and the convex strip detection piece 31 formed on the holder shaft side detection ring 4 and the holding cylinder side detection ring 22 are the same as those shown in FIG.

The structure of the quick change holder 80 is known in Japanese Utility Model Laid-Open No. 2-31609, and at the time of mounting, it is fitted into the two key grooves 82 provided on the end surface of the tip shaft portion 81 of the holding cylinder main body 77. Two locking claws 85 provided inside the sleeve 84 integrated with 83 are axially opposed to each other, and the fitting shaft 83 of the adapter 87 is fitted into the fitting hole 86 at the center of the holding cylinder main body 77.
Is inserted to position the locking claw 85 in the annular groove 88, and then the adapter 87 is rotated 90 degrees to move the locking claw 85 in the annular groove 88 from the key groove 82 by 90 degrees in the circumferential direction. Position, the locking claw 85 locks with the annular groove 88 to prevent the adapter 87 from moving in the axial direction, and at the same time, is integrated with the movable sleeve 89 that is biased axially rearward on the front side of the sleeve 84. The key member 90 is fitted into the key groove 82 by a spring force, and the adapter 87 is integrated with the holding cylinder body 77 in the circumferential direction. When detaching, the movable sleeve 89 is pulled forward in the axial direction, the key member 90 is removed from the key groove 82, and when the key member 90 is rotated 90 degrees in the opposite direction, the locking claw 85 corresponds to the key groove 82 and the adapter 87.
Can be removed axially and quickly replaced with another adapter 87 with another tool. In this structure, since the overload detection structure having the holder shaft side detection ring 4 and the holding cylinder side detection ring 22 is provided on the main shaft side, the tool 1
It is less expensive than conventional tool holders that have an overload detection structure for each two. Note that, instead of the thrust spring 8 and the torsion coil spring 18 of FIG. 7, the tool holder 1 of the present embodiment has a structure shown in FIG. 5, and the torsion coil spring alone can receive both thrust and torque. good.

[0015]

As described above, in the tool holder of the present application, a bearing for rotatably supporting the tool holding cylinder with respect to the holder shaft, a torsion coil spring for transmitting torque, or a single spring for receiving torque and thrust. Since the axial positions of and are overlapped with each other, the tool holder can be designed to have a small overall length, a small size and a light weight, and to have high rigidity. Therefore, the deflection accuracy of the tool holding portion can be improved, and fatigue fracture due to bending can be prevented even when using a carbide drill or a small diameter drill.

[Brief description of drawings]

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

FIG. 2 is a first vertical sectional view.

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

FIG. 4 is a development view of a detector.

FIG. 5 is a vertical sectional view of a tool holder according to a second embodiment.

FIG. 6 is a development view of a detector according to a second embodiment.

FIG. 7 is a vertical sectional view of a tool holder according to a third embodiment.

FIG. 8 is a perspective view showing a quick change chuck.

[Explanation of symbols]

1 Tool Holder, 2 Holder Shaft, 8 Thrust Spring, 11 Tool Holding Tube, 15 Rolling Bearing, 18
Torsion coil spring, 51 conversion mechanism, 53 torsion coil spring (spring), 80 quick change holder

Claims (3)

[Claims] 1. A tool holding cylinder is supported rotatably and axially movable with respect to a holder shaft, and the holder shaft and the tool holding cylinder are connected by a torsion coil spring that transmits the rotation of the holder shaft to the tool holding cylinder. In addition, in a tool holder provided with a thrust spring for biasing the tool holding cylinder forward with respect to the holder shaft, a bearing for rotatably supporting the tool holding cylinder with respect to the holder shaft and the torsion coil spring are provided. A tool holder characterized in that the axial positions are overlapped. 2. A holder shaft is provided with a conversion mechanism that rotatably and axially movably supports the tool holding cylinder with respect to the holder shaft, and converts the axial movement of the tool holding cylinder into circumferential rotation. A tool holder formed by connecting a tool holding cylinder with one spring that receives both thrust load and torque applied to the tool during cutting, and a bearing for rotatably supporting the tool holding cylinder with respect to a holder shaft. A tool holder characterized in that the tool holder is arranged so as to overlap the position of the spring in the axial direction. 3. The tool holder according to claim 1, wherein the tool holding cylinder is provided with a quick change holder at the tip of the holding cylinder body.