JPH0520203B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a drilling device with improved chip discharge performance using a drilling tool.

[Prior art]

A drilling tool such as an annular cutter or a twist drill that has a cutting blade at its tip has a groove connected to the cutting blade on its outer periphery, and chips generated during drilling are discharged out of the hole along the groove. The chips discharged out of the hole in this way vary depending on the material to be drilled, the cutting speed, and the feed rate of the drilling tool, but usually they are discharged continuously over a predetermined length. .

By the way, if the feed speed of the drill spindle is kept almost constant and thrust is applied to the drilling tool, the chips that are continuously ejected out of the hole become relatively long.
Due to its own weight and increased ejection resistance, the ejection performance of chips decreases, and the chips become clogged between the hole and the drilling tool, and the resulting increased cutting resistance impairs the free cutting performance of the drilling work. There was a problem that the efficiency decreased, and furthermore, the cutting blades were abnormally worn and the cutting blades became dull due to the frictional heat. As a simple countermeasure in this regard, conventionally, a barrier member is fixed to the casing located above the drilling tool so that it can come into contact with a continuous series of chips, and the chips come into contact with the barrier member. A technique has been proposed in which the chips are forcibly broken off by the impact or resistance of the cutting tool, but if such a barrier member is installed near the drilling tool, it not only interferes with the drilling operation, but also
There is no guarantee that the chips that are continuously discharged in a spiral or undulating manner will reliably come into contact with the barrier member. It is also possible to use a gun drill that supplies high-pressure cutting oil through the inside of the drilling tool and uses the pressure to flush out the chips along with the cutting oil.
In that case, a dedicated machine tool and tool head are required, and it is not applicable to portable or relatively small drilling machines such as drilling machines.

[Problem that the invention seeks to solve]

If the above-mentioned barrier member is used as a simple means to forcibly cut the chips that are continuously discharged from the hole, it will not only hinder the drilling operation but also cause the chips to come into contact with the barrier member. The present invention fundamentally solves this problem by selectively controlling the length of chips according to the drilling conditions and discharging them from the hole. The aim is to provide a drilling device that can.

[Means for solving problems]

As a means for solving the above-mentioned problems, the first invention of the present application is such that a drill spindle, which is provided with a mounting part of a drilling blade at its tip part, is pivotally supported on a casing so as to be able to reciprocate in the axial direction, and the drill spindle is A pair of thrust rings are fixed to the casing so as to face each other in the axial direction, and between the thrust rings, there are three or more rollers that can roll in contact with both opposing surfaces of the thrust rings. The main structure is a rotatable rotor support ring that supports a rotor, and the rotor support ring has three or more rotors so that the center of gravity is the center of rotation of the drill spindle. All the rolling elements are on a rolling track on one thrust ring, which is supported so as to be rotatable by regulating their mutual relative positions, and on which the rolling elements supported by the rolling element support ring roll. A plurality of recesses are formed to temporarily and simultaneously engage, and an operating member is further provided for selectively locking the rotor support ring to the other thrust ring.
The configuration is adopted.

In addition, the second invention of the present application is such that a drill spindle having a mounting portion of a drilling tool at its tip is supported on a casing so as to be able to reciprocate in the axial direction, and the drill spindle and the casing are provided with a pair of thrusters. A rolling element support in which rings are fixed so as to face each other in the axial direction, and three or more rolling elements that can roll in contact with both opposing surfaces of the thrust rings are supported between the thrust rings. The rotor support ring has a structure in which a ring is arranged rotatably and movably in the axial direction of the spindle, and the rotor support ring supports three or more rotors so that the center of gravity is the center of rotation of the drill spindle. are supported so as to be rotatable on their own axis by regulating their relative positions, and all the rolling elements are on the rolling track on one thrust ring on which the rolling elements supported by the rolling element support ring roll. A plurality of recesses are formed in which the rollers are temporarily and simultaneously engaged, and stoppers that can selectively lock the rotor support ring are formed on opposing surfaces of the pair of thrust rings. An operating member is provided for selectively moving the mover support ring to a position where it is locked by the stopper of one thrust ring, a position where it is locked by the stopper of the other thrust ring, and a position where it is not locked with the stoppers of both thrust rings. It adopts a configuration consisting of:

[Effect]

In the drill device according to the first invention, when the support ring of the rotor that rotates under the thrust direction load of the drill spindle is locked to the thrust ring that does not have a recessed portion, each of the rotors is rotated in the thrust direction. While rotating at a fixed position on the ring, it comes into rolling contact with a thrust ring having a recess, and the rolling elements fit into the respective recesses formed on the other thrust ring at each predetermined rotation of the drill spindle. Sometimes, the drill spindle, which applies thrust force to the drilling tool, is slightly displaced in the axial direction in response to the depth of the recess to momentarily stop cutting by the drilling tool, and then Therefore, the chips are cut into a predetermined length every predetermined rotation of the drill spindle and are discharged from the hole that is being drilled. When the rolling element support ring is in a free rotating state with respect to both thrust rings, each of the rolling elements supported by it rolls in rolling contact with both thrust rings, and the amount of rolling is: The stroke is half the rotation angle of the thrust ring that rotates integrally with the drill spindle, and the rotor support ring rotates relative to the rotation speed of the drill spindle. The number of displacements of the spindle in the direction opposite to the tip of the spindle relative to the number of revolutions of the spindle is half the number of displacements when the rotor support ring is fixed to one thrust ring that does not have a recess as described above. be done. In this way, chips are selectively cut into two different lengths and discharged in response to two-stage switching of the number of displacements of the drill spindle relative to its rotational speed.

The drill device according to the second invention is similar to the drill device according to the first invention, in which the number of backward displacements of the drill spindle relative to the rotational speed of the drill spindle is 2.
Depending on the stage switching, the chips are selectively cut into two different lengths and discharged. Furthermore, with the rotor fitted in the recess, the rotor support ring is cut into two different lengths and the other end is cut into two different lengths. When fixed to the thrust ring, each of the rolling elements rotates while always being connected to the recess on the other thrust ring, and rolls into contact with one of the thrust rings. does not apply axial displacement to the drill spindle, so if it is not necessary to cut chips intermittently, the chips are discharged without cutting.

〔Example〕

As shown in FIG. 4, the drill apparatus of this embodiment has an electromagnetic adsorption base 2 fixed to a desired position of a workpiece 1 by electromagnetic adsorption on a drill stand 3.
A drilling machine 5 is supported on the side of the stand 3, and is capable of moving forward and backward with respect to the workpiece 1 by rotating the lift operation handle 4 and operating an automatic feed unit (not shown). Become.

As shown in FIG. 1, the drilling machine 5 has a built-in electric motor (not shown) in a casing 6, and its motor shaft 7.
The rotation is slowed down by two sets of helical gears 8A to 8D and transmitted to a drill spindle 10 having a removable drilling blade 9 such as an annular cutter at its tip.

The tip of the drill spindle 10 protrudes from a housing block 11 screwed onto the lower end of the casing 6.
Radial needle bearing 12 fitted and fixed in
The middle portion of the drill spindle 10 is pivotally supported, and the upper end portion of the drill spindle 10 is pivotally supported on a radial needle bearing 14 provided on a partition plate 13 of the casing 6. On the drill spindle 10, the pair of radial needle bearings 1
The portion that can be contacted and supported by 2 and 14 is set to be slightly longer than the axial length of the bearing, so that the drill spindle 10 can be slightly reciprocated in the axial direction.

15 is the radial needle bearing 12
A flange-shaped first thrust ring is fixed to the outer periphery of the drill spindle 10 located above so as to be able to rotate integrally therewith. A disk-shaped second thrust ring 16 whose hole is loosely fitted into the drill spindle 10 is fitted and fixed to the casing 6.

Reference numeral 20 denotes a ball housing hole 2 into which three thrust balls 21, 21, 21 as rolling elements are fitted individually while being rotatable and regulating their relative positions.
Ball support ring with 2 (roller support ring)
The thrust rings 15 and 16 are rotatably fitted loosely around the outer periphery of the drill spindle 10, which is located in the space in which the thrust rings 15 and 16 face each other. As shown in FIG. 3, the ball accommodation holes 22 are arranged at different distances D from the center C2, which coincides with the axis of the drill spindle 10, so that the rolling orbits of the thrust balls 21 are different.
1, D2, and D3 (however, D1>D2>D3), and three pieces are formed so as to take relative angular positions θ1, θ2, and θ3 with respect to the same center C2. A part of the surface of the thrust ball 21 fitted in the ball accommodation hole 22 is connected to the ball support ring 20.
It protrudes from the upper and lower surfaces of the thrust rings 15 and 16 and can roll in contact with the opposing surfaces of the thrust rings 15 and 16, respectively.

A compression coil spring 26 is interposed between the first thrust ring 15 and the upper end surface of the radial needle bearing 12 via a spacer 25.
It is urged in a direction away from the workpiece 1 integrally with the drill spindle 10. Therefore, the first thrust ring 1
5 supports the drill spindle 10 integrated with the second thrust ring 16 in its thrust direction by elastically pressing the thrust ball 21 against the second thrust ring 16.

As described above, the thrust rings 15 and 16 are supported at three points while being elastically pressed by the three thrust balls 21, 21, 21, but the relative angle between the ball accommodation holes 22 is position θ
1, θ2, θ3 and the respective distances D1, D2, D3 with respect to the axis of the drill spindle 10 are
The forces acting on each support point are set so as to be balanced at the axial center position of the drill spindle 10,
The center C2 of the ball support ring 20 coincides with its center of gravity. As a result, the pair of thrust rings 15 and 16, the ball support ring 20, and the thrust ball 21 stably support the drill spindle 10 in the thrust direction regardless of the rotation speed without being subjected to eccentric rotation or tilting force. Furthermore, uneven wear of the individual thrust balls 21 and their rolling tracks is prevented.

On the upper end surface of the first thrust ring 15, on the respective rolling tracks L1, L2, L3 of the thrust balls 21 that are accommodated in the ball accommodation holes 22 and roll, the relative angular positions of the ball accommodation holes 22 are marked. θ
1, θ2, θ3 is the thrust ring 1
One spherical recess 27 with respect to the center C1 of 5 is formed at the same depth. Therefore, when the three thrust balls 21 are fitted into the recesses 27 at the same time, the first thrust ring 15, which is elastically biased by the compression coil spring 26 in the direction opposite to the tip end.
Then, the drill spindle 10 is moved back (displaced upward in FIG. 1) by a distance corresponding to the depth dimension of the recess 27. The depth of the recess 27 is set, for example, to be approximately equal to the maximum allowable thickness of chips to be scraped off by the punching blade 9. The maximum allowable thickness of chips is determined in relation to the maximum rotational speed of the drill spindle 10 and the maximum allowable feed rate of the drilling machine 5, which the drill device has as its maximum drilling capacity, and the material of the workpiece 1. be done.

In addition, protrusions 30 and 31 are formed radially on the outer peripheral edge of the upper end surface of the first thrust ring 15 and the outer peripheral edge of the lower end surface of the second thrust ring 16, respectively. Concave grooves 32 and 33 are formed on the outer periphery of the upper and lower surfaces of the ball support ring 20, and
A ball support ring 20 is located close to 5 and 16.
A guide chip 3 having a U-shaped cross section supports the ring so as to be slidable in the axial direction within the opposing space of the rings 15 and 16.
4, and the guide tip 34 is screwed into the tip of an operation knob 37 inserted through a long hole 36 formed from the outer wall of the casing 6 in the axial direction of the ball support ring 20 with a disc spring 35 interposed. Fixed. By moving this operation knob 37 along the elongated hole 36, the ball support ring 20 is
The locked state with the second thrust ring 16 is achieved by fitting the protrusion 31 into the groove 33, and the first thrust ring 1 is achieved by fitting the protrusion 30 into the groove 32.
5 and a non-latched state with both thrust rings 15 and 16.

The ball support ring 20 is attached to the second thrust ring 1
6, the thrust ball 21 accommodated and supported by the ball support ring 20 only rotates at a fixed position on the second thrust ring 16. Therefore, one rotation of the drill spindle 10 and the first thrust ring 15 The drill spindle 10 is engaged with the recess 27 at a rate of once every 30 minutes, thereby displacing the drill spindle 10 in the axial direction, which is being urged in the direction opposite to the tip by the compression coil spring 26. Therefore, in such a state, the drill spindle 10, which applies a downward thrust to the drilling blade 9, is displaced once per rotation in the direction opposite to the tip according to the depth of the recess 27, and the drilling blade 9
to momentarily stop cutting, thereby
The length of the chips is controlled to a cutting length determined by approximately one revolution of the punching blade 9.

When the ball support ring 20 is disengaged from the thrust rings 15 and 16 and the first thrust ring 15 is rotated integrally with the drill spindle 10, the upper surface of the thrust ball 21 rolls into contact with the second thrust ring 16. The three thrust balls 21
are relatively rolled and moved, and the ball support ring 20 rotates following this movement. Therefore, the relative rolling movement distance of the first thrust ring 15 with respect to the thrust ball 21 is the same as that of the second thrust ring 16.
When the first thrust ring 15 is rotated, the thrust ball 21 moves to the second position with a stroke that is half the rotation angle of the first thrust ring 15. It rolls and moves on the thrust ring 16. Therefore, once every two rotations of the first thrust ring 15 that rotates together with the drill spindle 10, the three thrust balls 21 are instantaneously combined with the respective recesses 27, and the drill spindle 10
sliding displacement in the axial direction. Therefore, in such a state, the drill spindle 10 is displaced in the direction opposite to the tip part depending on the depth of the recess 27 once every two revolutions, and the cutting by the drilling blade 9 is momentarily stopped. and thereby the length of the chip is
The cutting length is controlled to be determined by approximately two revolutions of the punching blade 9.

When the ball support ring 20 is locked and fixed to the first thrust ring 15 with the thrust ball 21 fitted into the recess 27, the thrust ball 21 accommodated and supported by the ball support ring 20 remains fitted into the recess 27 at all times. Since the drill spindle 10 that is integrated with the first thrust ring 15 only rotates in the fixed position of the first thrust ring 15 and rolls into contact with the second thrust ring 16.
is not displaced in the axial direction at all during its rotation,
Chip length is not specifically controlled.

The drilling blade 9 is an annular cutter, and a set screw 40 is attached to the cutter arbor 39 of the drill spindle 10.
A pilot pin 41 is fitted onto the axis of the punching blade 9 so as to be freely protrusive and retractable from the lower end surface of the punching blade 9. When the drilling tool 9 is attached to the drill spindle 10, the head of the pilot pin 41 is moved by the tip of the press piece 43, which receives the elastic force of the compression coil spring 42 housed in the cutter arbor 39 of the drill spindle 10. In this state, the tip of the pilot pin 41 is pressed against the punching knife 9.
The drill spindle 1 protrudes from the lower end surface and functions as the center of the drill spindle 9 during drilling.
According to the feed of 0, the cutter arbor 39 is idly rotated in contact with the surface of the workpiece 1, more precisely, the surface of the core, and the cutter arbor 39 is upwardly displaced, and when the drilling machine 5 is returned to the upward position after the completion of the drilling process, the compression coil The resilient force of the spring 42 pushes out the cut pieces from inside the punching blade 9.

Next, the operation of the above embodiment will be explained.

The first thrust ring 15 has three thrust balls 21 housed and supported in a ball support ring 20.
By elastically pressing the drill spindle 10 toward the second thrust ring 16, the drill spindle 10, which is integrated with the ring 15, is supported in its thrust direction.

For example, when drilling a hole with a relatively deep drilling depth using the drilling blade 9, that is, when the workpiece is relatively thick, the operation knob 37 should be moved to the center of the elongated hole 36 as shown in FIG. In this position, the ball support ring 20 is unlatched to the thrust rings 15 and 16, and the operation knob 37 is turned so as to maintain this state so that the guide tip 34 is tightly fixed to the inner surface of the casing 6. In this state, when the drill spindle 10 is driven to rotate, the thrust ball 21 accommodated and supported by the ball support ring 20 is rotated by the second thrust ring 16 fixed to the casing 6 and the first thrust ball 21 which rotates together with the drill spindle 10. 2 of the drill spindle 10 while rolling in contact with the opposing surfaces of the rings 15, respectively.
The second ball support ring 20 along with the rotation
During one rotation on the thrust ring 16, the three thrust balls 21 hit the recesses 27 provided on the respective rolling tracks L1, L2, and L3 once every two rotations of the drill spindle 10. When inserted at the same time, the drill spindle 10 and the first thrust ring 15, which are integral with each other and are under the elastic force of the compression coil spring 26, are inserted into the recess 2.
7 in the direction opposite to the tip, and is displaced upward in FIG. 1, changing from the state shown in FIG. 1 to the state shown in FIG. 2. Therefore,
During drilling, the drill spindle 10, which applies a downward feeding force along the thrust direction to the drilling blade 9 via the rotary operation handle 4 and an automatic feed unit (not shown), responds to the depth of the recess 27. When the sliding displacement occurs, the movement corresponds to substantially stopping the feed of the drilling tool 9 in the cutting direction, and the amount of displacement is equal to the maximum allowable thickness of chips scraped off by the drilling tool 9. At the same time, the cutting by the drilling tool 9 is stopped instantaneously, and the chips are controlled to the cutting length determined by approximately two rotations of the drilling tool 9, and the cutting length is approximately equal to that of the drilling tool 9. It will be intermittently discharged from the hole.

When the cutting diameter of the drilling blade 9 is relatively larger or the drilling depth is relatively shallow than in the above case, the fifth
As shown in the figure, by positioning the operation knob 37 at the upper end of the elongated hole 36, the protrusion 31 is engaged with the groove 33, and the ball support ring 20 is locked and fixed to the second thrust ring 16, and this state is maintained. Turn the operation knob 37 so that the guide tip 34 is tightly fixed to the inner surface of the casing 6. In this state, the ball support ring 20 is engaged with the second thrust ring 16, and when the drill spindle 10 is driven to rotate, the three thrust balls 21 accommodated and supported by the ball support ring 20 are moved to their respective positions. It rotates at a fixed position on the second thrust ring 16 and comes into rolling contact with the first thrust ring 15, and once per rotation of the drill spindle, it rotates on the rolling tracks L1, L2, L3 of the first thrust ring 15. At the same time, the drill spindle 10 and the first thrust ring 15, which are integral with each other, are displaced in the direction opposite to the tip by a distance corresponding to the depth dimension of the recesses 27. The state shown in FIG. 5 changes to the state shown in FIG. Therefore, in this case, the chips are controlled to a cutting length determined by approximately one rotation of the drilling blade 9, and are intermittently discharged from the hole in the middle of drilling.

In addition, when drilling into a workpiece that is so thin that it is not necessary to shred chips, or when drilling into a workpiece such as cast iron where chips are difficult to continue due to its own nature, In cases where the drilling tool itself has a chip breaking function, although the reliability of the chip shredding function is low, as shown in FIG. At the same time as locking in the groove 32, all the thrust balls 21 are fitted into the recesses 27, and the ball support ring 20 is locked and fixed to the first thrust ring 15, and the operation knob 37 is turned so as to maintain this state. The guide tip 34 is tightly fixed to the inner surface of the casing 6. In this state,
The thrust ball 21 accommodated and supported by the ball support ring 20 rotates together with the rotation of the first thrust ring 15 while always maintaining the fitted state with the recess 27, and is attached to the lower surface of the second thrust ring 16. Since the first thrust ring 15 and the drill spindle 10 are not displaced in the axial direction at all during their rotation, active cutting of chips is not performed.

Although the present invention has been described in detail based on the embodiments above, the present invention is not limited to the above embodiments, and can be modified in various ways without departing from the gist thereof.

For example, in the above embodiment, the number of displacements of the drilling blade 9 can be selectively changed to once or twice per two rotations of the drill spindle 10, but an annular cutter with a relatively large cutting diameter is used. In the case where the rolling raceway L1 of the above embodiment,
Two sets of recesses 27 into which three thrust balls 21 can fit simultaneously are formed in L2 and L3, respectively, so that the spindle 10 is selectively displaced once or twice for each revolution of the drill spindle 10. Alternatively, as shown in Fig. 8, three thrust balls share a common rolling track, and a set of recesses into which the three thrust balls can fit simultaneously is formed on the track. It is also possible to configure the drill spindle to be selectively displaced 6 or 3 times for every two rotations of the drill spindle, and the number of thrust balls, rolling tracks, and recesses can be changed according to various drilling conditions. By setting and combining them appropriately, while keeping the ratio of mutually switchable displacement times constant,
The ratio of the maximum number of displacements of the drill spindle to the number of rotations of the drill spindle can be variously changed to 1/2 or more.

Further, the rollers interposed between the pair of thrust rings are not limited to thrust balls, but may be changed to tapered rollers. Further, in the above embodiment, the recess 27
is provided in the first thrust ring 15, but may be provided in the second thrust ring 16, in which case,
The ball support ring 20 is connected to the first thrust ring 15.
By being locked to the drill spindle 10, the drill spindle 10 can be displaced in the direction opposite to the tip at a rate of once per rotation. Further, the drilling blade attached to the tip of the drill spindle is not limited to an annular cutter, but may be a twist drill.

In the above embodiment, the present invention is applied to a drill device equipped with a portable electromagnetic attraction base, but the present invention can also be applied to a small drilling machine or an electric drill.

〔Effect of the invention〕

When the rollers that roll under the thrust load of the drill spindle simultaneously engage their respective recesses every predetermined rotation of the spindle, the drill spindle, which is exerting an advancing force in the thrust direction on the drilling tool, It can be slightly displaced in response to the depth of the recess, and according to the present invention, cutting by the drilling blade can be stopped instantaneously and accurately, thereby cutting at every predetermined rotation of the drill spindle. It is possible to cut the chips into short and long pieces and intermittently discharge the chips from the hole that is being drilled. Therefore, the chips discharged outside the hole do not continue for a long time and the discharge performance deteriorates, and the chips do not get stuck between the hole and the drilling tool, unlike before. It is possible to reliably prevent a situation in which free machinability is impaired and drilling work efficiency is reduced, or furthermore, the cutting blade is abnormally worn.

Moreover, when the rotor support ring is in a free rotation state with respect to both thrust rings, the rotor support ring rotates relative to the drill spindle at half the rotation speed, so the rotation speed of the drill spindle at that time is The number of displacements of the spindle in the direction opposite to the tip of the drill spindle is theoretically half the number of displacements when the rotor support ring is fixed to a thrust ring without a recess. The number of displacements of the spindle relative to the rotational speed can be set in two stages, and chips can be selectively discharged at two different lengths depending on the drilling conditions. Selection of the chip length according to the drilling conditions can be achieved by changing the position of the rotor support ring using the operating member, without disassembling the drilling equipment or replacing parts. Therefore, the chip length can be easily optimized depending on the drilling conditions.

In addition, by locking the rolling element support ring to the thrust ring that holds the recess while the rolling element is fitted into the recess, each of the rolling elements is always connected to the recess on the thrust ring. While rotating on its axis, it rolls into contact with the thrust ring on the opposite side,
If it is possible to avoid axial displacement of the drill spindle and thereby avoid the need to cut chips intermittently, drill by selecting an operation that ejects chips without cutting. It can also be processed.

[Brief explanation of the drawing]

The drawings show an embodiment of the drill device according to the present invention, and FIG.
A vertical cross-sectional view showing the normal state around the drill spindle during cutting, with the ball support ring capable of displacing the spindle once per two rotations of the drill spindle. FIG. 3 is a vertical cross-sectional view showing the state around the drill spindle when cutting is interrupted in the ring positioning state. FIG. 4 is a schematic front view showing the entire drill device, and FIG. 5 is a perspective view showing the relationship between the drill spindle and the recess, and FIG. Fig. 6 is a longitudinal sectional view showing the normal state around the drill spindle during cutting, and Fig. 6 shows the normal state around the drill spindle when cutting is interrupted, with the ball support ring capable of displacing the spindle once per revolution of the drill spindle being positioned. Fig. 7 is a longitudinal sectional view showing the state in which the ball support ring is positioned so that displacement of the drill spindle is impossible, and Fig. 8 is a longitudinal sectional view showing the ball support ring regulated by the ball support ring. FIG. 7 is a perspective view showing another combination of a track and a recessed portion of a thrust ring formed on the track. 5... Drilling machine, 6... Casing, 9... Drilling blade, 10... Drill spindle, 15... First
Thrust ring, 16...Second thrust ring,
20...Ball support ring (roller support ring),
21... Thrust ball (roller), 22... Ball accommodation hole, 27... Recess, L1, L2, L3...
...Rolling raceway, 30 and 31...Protrusion, 32 and 3
3...concave groove, 37...operation knob.

Claims (1)

[Scope of Claims] 1. A drill spindle having a drilling tool mounting portion at its tip is pivotally supported in a casing so as to be movable back and forth in the axial direction, and the drill spindle and the casing are provided with A pair of thrust rings are fixed facing each other, and between the thrust rings is a rolling element support ring that supports three or more rolling elements that can roll in contact with both opposing surfaces of the thrust rings. The rotor support ring rotates three or more rotors by regulating their relative positions with respect to each other so that the center of gravity is the center of rotation of the drill spindle. On the rolling track on one of the thrust rings on which the rolling elements supported by the rolling element support ring roll, there is a recess in which all the rolling elements temporarily and simultaneously engage. A drill device comprising: a plurality of rotor support rings; and an operating member for selectively locking the rotor support ring to the other thrust ring. 2. A drill spindle, which is equipped with a mounting portion of a drilling tool at its tip, is supported by a casing so as to be movable back and forth in the axial direction, and the drill spindle and the casing have a pair of holes facing each other in the axial direction of the drill spindle. A thrust ring is fixed, and between the thrust rings is a rotatable rotor support ring that supports three or more rolling elements that are in contact with both opposing surfaces of the thrust ring and are rotatable. The drill device is arranged to be movable in the axial direction of the drill spindle, and the rotor support ring moves three or more rotors in relative positions with respect to each other so that the rotation center of the drill spindle is the center of gravity. All the rolling elements are temporarily and temporarily supported on the rolling track on one thrust ring, on which the rolling elements supported by the rolling element support ring roll. A plurality of concave portions are formed to engage at the same time, and further, stoppers capable of selectively locking the rotor support ring are respectively formed on opposing surfaces of the pair of thrust rings, and the rotor support ring is ,
A drill device comprising an operating member that selectively moves one thrust ring to a position where it is locked by a stopper, the other thrust ring to a position where it is locked by a stopper, and a position where both thrust rings are not locked to the stopper.