FR2653372A1 - IMPROVEMENT TO A CHUCK. - Google Patents

Abstract

Disclosed is a mandrel having a number of claws which are mounted centrally at its front end to be able to slide in and out of each other, and a control ring mounted peripherally to the body of the mandrel to be able to rotate in opposite directions. in order to rotate a threaded ring to move the claws. According to the invention, the mandrel comprises a locking means (22) between its body (11) and the claws (12) and a torque amplifier means (17) arranged between the locking means (22) and the control ring (18) to reduce the rotation of this ring and output an amplified torque for the threaded ring (15) when the locking means is locked on the chuck body, and to transmit the rotation of the control ring to the threaded ring when the locking means is released from the mandrel body. The invention applies in particular to mechanical punches and mechanical screwdrivers.

Description

The present invention relates to mandrels for attachment to

  mechanical punches, mechanical screwdrivers and the like, for holding tools such as drills and screwdriver bits, and more particularly to the type of chuck which is tightened to

the hand, without using a handle.

  A conventional mandrel of the type having a rotatable rotating ring with a handle of the mandrel for extending and removing the claws of the mandrel involves complicated operation of the handle, careful maintenance of the handle and other disadvantages. To eliminate these disadvantages, a mandrel has already been developed which has a rotating ring, turned by hand without using a handle to clamp the chuck claws, and a locking device to prevent

  claws to loosen during an operation.

  However, with a mandrel having such a locking device, the tool will run empty at the expense of an effective operation if the claws of the

  mandrel impart insufficient clamping force.

  In order to obtain a large clamping force, it is conceivable to increase the torque by reducing the rotation of the ring by an appropriate reduction mechanism. However, this will give rise to a problem in that the mandrel will not work quickly because the claws will be forced to slide at a reduced speed even when an inserted tool will not be clamped by

claws.

  The main object of the present invention is to provide a mandrel comprising a locking device disposed between a mandrel body and claws that can slide by screwing, the locking device pressing and locking on the body of the mandrel by a reaction force which occurs. when the claws block a tool, and a torque enhancing device disposed between the locking device and a rotatably mounted control ring on the body of the mandrel, the torque enhancing device reducing the rotation of the control ring to emit an amplified torque for a ring that advances by screwing the claws of the mandrel when the locking device is locked on the body of the mandrel, so that the claws slip quickly until they contact a tool inserted into position to achieve a

quick clamping action.

  Another object of the present invention is to provide a mandrel where the rotation of the control ring occurs with an automatically increased torque as the claws contact and hold the tool, thereby forcing the claws to slide with the increased torque to maintain the torque. tool with a high clamping force. The invention will be better understood and other purposes, features, details and advantages thereof

  will become clearer during the description

  following explanatory diagram with reference to the accompanying schematic drawings given solely by way of example illustrating several embodiments of the invention and in which: - Figure 1 is a vertical sectional view of a mandrel according to a first embodiment of the invention; production; FIG. 2 is an exploded perspective view of a torque amplifier mechanism; - Figure 3 is a schematic view illustrating rolling grooves; - Figure 4 is a vertical sectional view of a mandrel of a second embodiment; - Figure 5 is a sectional view taken along the line I-I of Figure 4, illustrating an operation; - Figure 6 is a sectional view taken along the line II-II of Figure 4, illustrating an operation; - Figure 7 is a vertical sectional view of a mandrel of a third embodiment; - Figure 8 is a sectional view taken along the line III-III of Figure 7; - Figure 9 is a vertical sectional view of a mandrel of a fourth embodiment; - Figure 10 is a vertical sectional view of a control ring; Figure 11 is a side view of the control ring; - Figure 12 is a vertical sectional view of a mandrel of a fifth embodiment; - Figure 13 is an enlarged partial view, in vertical section, of a torque amplifier mechanism in the inactive position; Figure 14 is an enlarged partial view, in vertical section, of the torque amplifier mechanism in the active position; and FIG. 15 is an enlarged partial view, in vertical section, of a mandrel of a sixth embodiment. A first embodiment of the present invention will be described in detail below with reference to

at drawings.

  Figures 1 to 3 show a mandrel of a first embodiment. This chuck is used with a mechanical drill or a mechanical screwdriver to hold a tool such as a drill bit or a screwdriver bit. Referring to Figures 1 and 2, the mandrel comprises three claws 12 mounted sliding

  centrally at the front end of the body 11 of the mandrel.

  The claws 12 are inclined with their respective forward ends converging towards the axis of the body

11 of the mandrel.

  More particularly, the claws 12 are mounted simply sliding in grooves 13 which are formed in the body 11 of the mandrel being inclined relative to its axis, respectively. Each claw 12 defines a partial male screw 14 on its peripheral portion, with the threads of the screw arranged to form a continuous assembly. The respective partial male screws 14 are engaged with a female screw 16 defined in a threaded ring 15. By rotating the ring 15 in opposite directions, the claws 12 slide towards and away from each other to tighten and

release a tool.

  A torque amplifier mechanism 17 is mounted peripherally to the ring 15 and a control ring 18 is peripherally mounted to the torque amplifier mechanism 17. When the control ring 18 is turned forwards or backwards, it is in one direction to tighten or release the tool A, the torque is transmitted to the threaded ring 15 by the

  torque amplifier mechanism 17.

  The mechanism 17 is constructed as follows.

  It comprises three annular elements, that is to say an outlet ring 20 press-fitted into and fixed to the threaded ring 15, a relatively rotatably supported input ring 21 in the control ring 18 and offset by predetermined amount of eccentricity e and a movable locking ring 22 in pressure contact with a rear position of the mandrel body 11 through tapered peripheral surfaces. These annular elements are arranged axially

to the body 11 of the mandrel.

  The inlet ring 21 defines a hypocycloid rolling groove 23 having an arcuate section

  on its surface which is opposed to the locking ring 22.

  The locking ring 22 defines an epicyclic rolling groove 24 having arcuate sections on a surface opposite to the inlet ring 21. A number of balls 25 are arranged between these race grooves 23

  and 24 to ride along them.

  As also shown in FIG. 3, the race grooves 23 and 24 have an amplitude corresponding to the amount of eccentricity e of the inlet ring 21. The inlet ring 21 has ten waves and the locking ring 12 in twelve. The number of balls 25 arranged

between them is eleven or less.

  When a revolution due to the amount of eccentricity e is applied to the inlet ring 21 having the race grooves 23 and 24, the balls 25 roll along these grooves 23 and 24 to rotate the inlet ring 21 Since the rotation is considerably reduced with respect to the revolution, the rotation of the inlet ring 21 results in the

production of an amplified torque.

  As, in this embodiment, the rolling groove 23 of the inlet ring 21 has ten waves and the rolling groove 24 of the locking ring 22 has twelve, the difference in the number of waves being two. , the

  reduction ratio is 2/10 waves = 1/5.

  A fairly large reduction ratio can be achieved by increasing the number of waves. If, for example, the input ring 21 has forty waves and the difference in the number of waves is two, 2/40 waves = 1/20, which makes it possible to produce a pair

greatly amplified.

  To transmit the rotation of the inlet ring 21 to the outlet ring 20, a number of

  balls 26 are arranged between their opposite surfaces.

  More particularly, the inlet ring 21 defines recesses (not shown) for receiving the balls 26 while the ring 20 defines recesses 27 which face them. The recesses 27 of the outlet ring 20 have a size (of annular shape) allowing the balls 26 to rotate by the same amount of eccentricity so that the energy transmission is possible despite the eccentric rotation of the ring

entrance 21.

  To secure the locking ring 22 to the body 11 of the mandrel, the ring 22 defines, at its center, a tapered pressure contact surface 28 which diverges rearwardly while the body 11 of the mandrel defines

  a corresponding pressure contact surface 29.

  These surfaces come into pressure contact with each other when the locking ring 22 is pushed by a return of the threaded ring 15 (with removal of the claws 12), and the locking ring 22 is fixed to the

body 11 of the mandrel.

  The locking ring 22 defines teeth 30 at its circular rear end. An elastic ring 33 is disposed at the rear end of the locking ring 22, the elastic ring 33 defining a number of elastic elements 32 having pawls 31 in elastic engagement with the teeth 30. The elastic ring 33 further defines fixing protuberances 34 for pressure fitting in the grooves defined on an inner wall of the control ring 18 so that the elastic ring 33 is

  retained in position and against a rotation.

  The elastic members 32 perform at least three functions. One of them is the application of a biasing force to separate the above mentioned pressure contact surfaces 28 and 29. The second function is to engage the locking ring 22 and force it to turn with the control ring 18 because, otherwise, the locking ring 22 would be freely rotatable when it is out of pressure contact with the body 11 of the mandrel. The third function is a locking function for fixing the ring 22 which can be released by reaction, even when it is pressed against the body 11 of the mandrel. A cover 36 is mounted at the rear end of the control ring 18 and is press-fitted by its base to a rear position of the body 11 of the mandrel. The elastic ring 33 is attached to the control ring 18 of this embodiment but may be

fixed to the body 11 of the mandrel.

  The threaded ring 15 consists of two parts which are rigidly interconnected by press fitting of the outlet ring 20 after assembling the two parts to the body 11 of the mandrel. The interconnection can be achieved by any other means, for example by defining the threads on the two elements for tightening by screwing, or by a fluted engagement with a flange ring provided to prevent separation. In FIGS. 1 and 2, the numeral 37 denotes a pad provided in the inlet ring 21 for a

  regular rotation of the control ring 18.

  The way the chuck 10 built above

  will work will be described now.

  It is assumed that the claws 12 are wide open, being ready to hold the tool A. The tool A is placed in position and the control ring 18 is turned in the clamping direction to force the claws 12 to clamp the tool A Since, at the initial stage of this operation of rotation of the ring, the claws 12 are free of the load resulting from the clamping of the tool A, the locking ring 22 of the torque amplification mechanism 17 is in a free state. relative to the body 11 of the mandrel. Furthermore, since the locking ring 22 is in engagement with the elastic members 32, the outlet ring 20, the inlet ring 21 and the locking ring 22 are interconnected in one unit and rotate together. As a result, the rotation of the control ring 18 directly causes an equal rotation of the threaded ring 15, which produces a fast forward for the projection of

claws 12.

  A load acts on the claws 12 when they contact and begin to tighten the tool A. This load causes a return of the ring 15, which pushes the locking ring 22 backwards, via the

  outlet ring 20 and the inlet ring 21.

  As a result, the pressing contact surfaces 28 and 29 of the locking ring 22 and the body 11 of the mandrel come into pressure contact. The elastic elements 32 bend at this pressure contact, resulting in their sliding. The locking ring 22 is then fixed to the body 11 of the mandrel, to place the

  torque amplifier mechanism 17 to an active state.

  Indeed, the rotation of the control ring 18 causes a revolution of the inlet ring 21, and thus the balls 25 roll along the race grooves 23 and 24 to rotate the inlet ring 21. The rotation of the inlet ring 21 is transmitted to the outlet ring 20 in the form of a high torque resulting from the reduction of the inlet, to rotate the ring 15 and project the claws 12 and force them to

  tighten tool A to high torque.

  When performing an operation with the tool A held by the claws 12 as described above, the tool A which can be a screwdriver bit, for example, is rotated in opposite directions.

depending on the nature of the operation.

  If this operation involves the forward rotation of the tool A, which acts on the control ring 18, the torque booster mechanism 17 and the threaded ring 15 in the direction tending to clamp the claws 12, then the rotation towards the rear acts on these components 18, 17 and 15 in one direction to release the claws 12. Even if a reaction occurs with the reversal of the rotation acting in the direction releasing the claws 12, in reality no loosening will occur because the locking ring 22 is in engagement with the elastic members 32 to rigidly connect the control ring 18, the torque amplifier mechanism 17 and the threaded ring 15 to the

body 11l of the mandrel.

  When the tool A is released, the control ring 18 simply has to be rotated towards the release direction. Then, the claws 12 are released under a high torque because the torque amplifier mechanism 17

  is in its active state at the initial stage of rotation.

  When the claws 12 are even more relaxed to eliminate the return of the threaded ring 15, the elastic members 32 push back the locking ring 22. As a result, the pressing contact surfaces 28 and 29 of the ring 22 and the body 11 of the mandrel come out of the pressure contact. The ring 15 rotates rapidly at the same speed as the control ring 18 to move the claws 12 quickly in the direction of release. According to this embodiment, the tool A is held by means of a clamping force amplified by the torque amplification mechanism 17. Thus, the tool A is held rigidly in a manner equivalent to the case

of using a handle.

  Furthermore, the torque amplifier mechanism 17 comprises the three rings, that is to say the outlet ring 20, the inlet ring 21 and the locking ring 22. This construction is compact and allows easy connection with the claws 12. Despite the

  simple construction, we can transmit a great couple.

  The biasing engagement produced by the resilient members 32 serves to prevent loosening of the control ring 18 and claws 12 due to vibrations occurring during an operation. This promotes the clamping of tool A with increased rigidity. In addition to the function preventing loosening, the elastic members 32 have functions of engagement of the control ring 18 for a rigid connection, to retain the control ring 18 on the body 11 of the mandrel and to release the body 11 of the mandrel and claws 12 of mutual pressure contact when removing the tool A claws 12. This single component fulfilling these functions allows the construction to be compact with a reduced number of components. In the first embodiment above, the output of the input ring 21 is transmitted to the

  threaded ring 15 by the outlet ring 20.

  Alternatively, the output can be done by a gear coupling actively connecting the inlet ring 21 and the threaded ring 15 and able to absorb

  the eccentric rotation of the inlet ring 21.

  Furthermore, in the first embodiment, the claws 12 are displaced by the action of the threaded ring 15 provided peripherally thereto. The torque amplifier mechanism 17 can be applied to the type of claws which are pushed and pulled by a sleeve provided at the rear end of the

  claws and led by screw rotation.

  Figures 4 to 6 show a mandrel of a second embodiment. In Figure 4, the mandrel comprises three claws 42 slidably mounted in a body 41, to be able to protrude and retract through rotations in opposite directions of a threaded ring 43, such as

  in the first embodiment shown in Figure 1.

  A detailed description of this arrangement is omitted

  right here. The threaded ring 43 consists of two parts which are rigidly interconnected by fitting to

  pressure of a peripheral sleeve 44.

  The body 41 of the mandrel carries a cylindrical control ring 45 which is rotatably mounted on an intermediate peripheral portion. A cylindrical cover 46 fits and is attached at the periphery to a

  proximal end of the body 41 of the mandrel.

  A torque enhancing mechanism 47 is provided in a power transmission path between the threaded ring 43 and the control ring 45 for

  transmitting the torque of the ring 45 to the ring 43.

  The torque amplifier mechanism 47 comprises an inlet / outlet ring 48 which rotates in the control ring 45, and a ring of

  blocking 49 rotatably mounted on the body 41 of the mandrel.

  The inlet / outlet ring 48 has a forward inner wall which fits, via a needle bearing 50, to the outer peripheral surface of a tubular control section.

  51 which is formed in the center of the control ring 45.

  As also shown in FIG. 5, the outer peripheral surface of the tubular control section 51 is formed around an axis C which is offset by an amount e with respect to an axis B of the body 41 of the mandrel. The inlet / outlet ring 48 has an intermediate inner wall in driving engagement, by a gear coupling 52, with a circumference

  external of a rear end of the threaded ring 43.

  More particularly, this coupling 52 is freely engaged with a pinion 53 which is formed on the intermediate inner wall of the inlet / outlet ring 48 and with a pinion 54 formed on the outer periphery at the rear end of the ring. threaded 43, to allow the eccentricity of the quantity e. Furthermore, the inlet / outlet ring 48 has a rear inner wall defining a pinion 55 which, as also shown in FIG. 6, is engaged with a pinion 56 formed peripherally to the locking ring 49. These pinions 55 and 56 form cycloidal gears to produce a cycloidal motion. When the control ring 45 is rotated to rotate the inlet / outlet ring 48 by the eccentricity of the tubular control section 51, the difference in the number of teeth between the pinion 55 formed on the inlet / outlet ring 48 and the pinion 56 formed on the locking ring 49 results in a rotation of the inlet / outlet ring 48 corresponding to the additional number of teeth. As a result, the rotation of the inlet / outlet ring 48 is greatly reduced and the rotation

  of this ring 48 produces an amplified output torque.

  If, for example, the pinion 56 of the locking ring 49 has 66 teeth and the pinion 55 of the input / output ring 48 has 68, the difference in the number of teeth being two, the reduction ratio is of 2/66 teeth = 1/33. Thus, the reduction ratio of 1/33 with respect to an input is obtained and the input / output ring 48 produces a greatly amplified output torque. An appropriate number of thrust balls are mounted for rolling movement between the opposed surfaces of the threaded ring 43 and the lock ring 49. The lock ring 49 has an inner peripheral wall which defines a tapered pressure contact surface. 56 which diverges rearward, while the body 41 of the mandrel has an intermediate outer peripheral wall defining a tapered pressure contact surface 59 which opposes the contact surface 58 and

  which diverges backwards to match him.

  These pressure contact surfaces 58 and 59 move in pressure contact with each other when the threaded ring 43 is withdrawn by a return of the claws 42 of the mandrel resulting from the tightening of the ring 43 to tighten the tool A , so that the ring of

  blocking 49 is fixed to the body 41 of the mandrel.

  An elastic ring 60 is fixed in a peripheral inner wall of the control ring 45 to face the rear end of the locking ring 49. The elastic ring 60 comprises elastic members 61 formed around interior and engaging peripheral portions. a toothed surface at the end of the locking ring 49. In this way, the control ring 45 and the locking ring 49 are rigidly interconnected and the locking ring 49 and the body 41 of the mandrel are biased in a direction to

  separate the pressure contact surfaces 58 and 59.

  A retaining ring 63 is fastened by press-fitting towards the rear of the elastic ring 60 for

  keep it in position and against rotation.

  The way the mandrel 40 constructed according to the second embodiment is tightened and released will be

described next.

  When the tool A is clamped by the three claws 42, the control ring 45 is turned in the tightening direction D (indicated by the arrows in solid lines in FIGS. 5 and 6) to tighten the tool A, the cover 46. being blocked against any rotation. Since, at the initial stage of this rotation operation, the claws 42 are disengaged from the load resulting from the clamping of the tool A, the locking ring 49 which forms part of the torque amplifier mechanism 47 is rotatable relative to the body 41 of the mandrel. . Furthermore, since the locking ring 49 is connected to the control ring 45 by the elastic members 61, the ring 45, the inlet / outlet ring 48 and the locking ring 49 rotate together. As a result, the rotation of the control ring 45 directly causes a rotation of an equal amount of the threaded ring 43, which produces a fast screwing for the rapid passing of the claws 42 in order to tighten the tool A. Subsequently, a charge acts on the claws 42 when they contact and start to tighten the tool A. Then the threaded ring 43 is removed by a return due to tightening, which pushes the locking ring 49 backwards by the balls As a result, the pressing contact surfaces 58 and 59 of the locking ring 49 and the body 41 of the mandrel move in pressure contact with each other. The elastic elements 62 bend under this pressure contact, resulting in their sliding. The locking ring 49 is then fixed to the body 41 of the mandrel to place the torque amplifier mechanism 47 in an active state.

  and produce the speed reduction effect.

  Indeed, the rotation of the control ring forces the tubular control section 51 to rotate the input / output ring 48 of the amount of eccentricity. This produces a rotation of the input / output ring 48 based on the difference in the number of teeth between the pinion 55 formed on the input / output ring 48 and the pinion 56 formed on the locking ring 49. in the form of a high torque resulting from the reduction of the inlet, to turn the threaded screw 43 and advance the claws 42, thereby forcing them to tighten the tool A with a high torque. When performing an operation by means of the tool A held by the claws 42 as described above, the elastic members 61 engaging the locking ring 49 serve to stop the relaxation resulting from rotation in the direction to release the

claws 42.

  When the tool A is released, the control ring 45 must simply be turned towards the release direction E (which is indicated by the arrows in

dotted in Figures 5 and 6).

  When the claws 42 are removed to eliminate return due to clamping and action on the threaded ring 43, the locking ring 49 is advanced by the biasing force of the elastic members 61. As a result, the pressure contact surfaces 58 and 59 of the locking ring 49 and the body 41 of the mandrel come out of pressure contact. Then, the reduction effect of the torque amplifier mechanism 47 is canceled, and the control ring 45, the input / output ring 48 and the lock ring 49 rotate together. The ring 43 rotates at the same speed as the control ring 45 to quickly move the claws 42 in the direction of release. As a result, the claws 42 slide rapidly away from each other to release the tool A. When the tool A is held, the torque is reduced and amplified by the torque amplifier mechanism 47 as described above. Thus, a greater torque is obtained with respect to the moment when the torque of the control ring 45 is directly transmitted to the threaded ring 43 in engagement with the respective claws 42. By simply turning the control ring 45 in the tightening direction, the tool A can be rigidly tightened and held in position. Furthermore, the control ring 45, the inlet / outlet ring 48 and the locking ring 49 can be turned together in opposite directions during the rotation operation performed, until the tool A is locked in position. position and rotation operation after its release. The screws 42 are quickly screwed to and away from each other by the ring 43 to lock and release the tool A. Thus, the construction has

excellent operability.

  The following construction may be provided in place of the tubular control section 51 of the second

embodiment.

  The control ring 45 may have an inner peripheral wall offset by the amount e with respect to the axis B of the body 41 of the mandrel, with the inlet / outlet ring 48 freely fitted in this eccentric inner peripheral wall, the ring 48 being rotatable along the inner peripheral wall

  eccentric of the control ring 45.

  Such a construction will be described below in the form of a third embodiment, the emphasis being placed on the mechanism

torque amplifier.

  Figures 7 and 8 show a mandrel of the third embodiment. This chuck has the same basic construction as that of the second embodiment and identical components have received the same reference numbers and their particularities

will not be described.

  The control ring 45 has an inner peripheral wall formed about an axis C which is offset by an amount e with respect to the axis B of the body 41 of the mandrel. The inlet / outlet ring 48 of the torque amplifier mechanism 47 is rotatably attached in the concentric inner circumferential wall 70 of the control ring 48 via a number of balls 71. When the control ring 45 is turned, the input / output ring 48 can turn along this

  eccentric peripheral inner wall 70.

  A sleeve 72 press-fit peripherally to the threaded ring 43. The gear coupling 52 comprises a pinion 53 formed on an inner wall at the front end of the inlet / outlet ring 48 and a toothing 54 formed around

outer sleeve 54.

  Furthermore, the inlet / outlet ring 48 has a rear inner wall defining a pinion 55 which is engaged with a pinion 56 formed peripherally to the locking ring 49. These pinions 55 and 56 form cycloidal gears. The number of teeth of these gears 55 and 56 are chosen as in the second embodiment. When the control ring 45 is rotated, the torque amplifier mechanism 47 forces the tool A to

  be tight as in the second embodiment.

  In the initial stage of this rotation operation, when the claws 42 do not tighten the tool A, the control ring 45, the inlet / outlet ring 48 and the locking ring 49, however, turn together to rotate the ring 43. at the same speed as the control ring 45 as described in the second embodiment. The rapid screwing by the screw 43 forces the claws 42 to move towards each other rapidly to tighten the tool A. Subsequently, a load acts on the threaded ring 43 when the claws 42 contact and start to tighten A tool A. Then, the threaded ring 43 is removed by the return due to tightening, which pushes the locking ring 49 back through the thrust balls 57. As a result, the pressure contact surfaces 58 and 59 of the locking ring 49 and the body 41 of the mandrel move in pressure contact with each other. The elastic elements 62 bend under this pressure contact, which results in their sliding. The locking ring 49 is then fixed to the body 41 of the mandrel to place the torque amplifier mechanism 47 in an active state and

  produce the speed reduction effect.

  Indeed, the rotation of the control ring forces the eccentric inner wall 70 to rotate the input / output ring 48 of the amount of eccentricity. This produces a rotation of the inlet / outlet ring 48 based on the difference in the number of teeth between the pinion 55 formed on the inlet / outlet ring 48 and the pinion 56 formed on the locking ring 49. rotation is transmitted as a high torque resulting from the reduction of the inlet, to rotate the threaded ring 43, through the coupling 52, and advance the claws 42 to

  force them to tighten tool A to high torque.

  When the tool A is released, the control ring 45 must simply be turned towards the release direction E (indicated by the dashed arrow in FIG. 8), as has already been described for the second mode

  of realization. A detailed description will be by

therefore omitted.

  It is possible to expect, from the third embodiment as constructed above, functions and advantages equivalent to those of the second embodiment. Figures 9, 10 and 11 show a mandrel of a fourth embodiment. This fourth embodiment relates to another example of the support of the input / output ring 48 of the third embodiment. The torque amplifier mechanism 47 and other basic constructions are identical to those of the third embodiment, and the identical components have received identical reference numerals,

  they will not be described in detail.

  As in the third embodiment, the control ring 45 has an inner peripheral wall offset from the axis of the body 41 of the mandrel. The inlet / outlet ring 48 of the torque amplifier mechanism 47 rotates in the concentric inner circumferential wall 70 of the control ring 45. When the ring 45 is rotated, the inlet / outlet ring 48 can turn along this wall

  Eccentric peripheral interior 70.

  The rotatable input / output ring 48 as above is supported by a number of needle bearings 74. These needle bearings 74 are arranged only along an extent.

circumferential circumference.

  Indeed, the cycloidal pinion 56 of the locking ring 49 makes a revolution and rotates while partially engaging the cycloid pinion 55 of the input / output ring 48. This engagement takes place on a

  fixed extent with regard to the control ring 45.

  The load produced by clamping tool A results in a radial pressure that acts only in

the above scope of commitment.

  Thus, the needle bearings 74 are provided along the partial circumferential extent of the control ring 45 where the gears 55 and 56 are in engagement with each other and the load is applied. The needle bearings 74 have ends protruding slightly toward the locking ring 49. The locking ring 49 defines a circumferentially extending attachment groove 75 which faces the protruding portions of the needle bearings 74. 75 receives the protruding portions of the bearings 74 to allow movement due to rotation (movement relative to the ring

  locking 49) needle bearings 74.

  The load produced by the clamping of the tool A acts on the needle bearings 74 and radially presses the bearings 74 as noted above. Therefore, when the control ring 45 is formed of a synthetic resin, the pressure force tends to partially expand and deform the control ring 45. This deformation of the ring 45 outward is suppressed because the ends of the needle bearings 74 fit very precisely into the groove 75, against an outside spreading under the

pressure.

  When the control ring 45 is expanded outward, it fills the space between its outer periphery and the cover 46, which is effective to prevent the entry of dust and other materials

foreigners in space.

  When the force is applied to radially extend the needle bearings 74 as noted above, this load is applied to the portion of the control ring 45 inwardly. As a result, an internal force is produced in the control ring

  to cause a twist with its outer portion.

  In order to resist twisting, needle bearings 76 are provided on an inner peripheral wall in the portion of the control ring 45 outwardly to oppose needle bearings 74. These needle bearings 76 prevent

torsion of the control ring 45.

  Needle bearings 74 and 76 can be provided in a small number. With the protruding portions of the needle bearings 74 held in the fixing groove 75 of the locking ring 49, the deformation of the ring 49 due to the load of

  tightening of the tool can be avoided.

  The structure of the bearings described above can also be applied to the chuck of the first mode of

  embodiment shown in Figure 1.

  In Fig. 9, the resilient ring 60 comprises a resilient material that has the shape of an inclined flange and holds a number of balls 77 in a number of positions. These balls 77 engage and load by spring the toothed face 62 which extends over

  all around the locking ring 49.

  The elastic ring 60 thus formed has functions and advantages equivalent to those offered by the

third embodiment.

  In FIG. 11, recesses 78 serve to lock the elastic ring 60 and the latter defines protuberances (not shown) that can come into

engagement with these recesses.

  Figures 12, 13 and 14 show a fifth embodiment of a mandrel according to the invention. In FIG. 12, the mandrel 100 comprises three claws 102 slidably mounted in a mandrel body 101, to be able to protrude and be withdrawn by opposite rotations of a threaded ring 103, as in the first

  embodiment shown in Figure 1. A description

  detailed description of this arrangement is omitted here.

  The threaded ring 103 consists of two parts which are rigidly interconnected by fitting to

  pressure of a peripheral sleeve 104.

  A lid 105 having a U-shaped section is attached to the outer periphery of a proximal end of the body 101 of the mandrel. The body 101 carries a cylindrical control ring 106 rotatably mounted on an intermediate peripheral portion thereof. The outer periphery of an open end of the control ring 106 is relatively rotatably attached to the inner periphery of the proximal end of the

cover 105.

  An amplifier torque mechanism 107 is provided between the control ring 106 and the threaded ring 103 to transmit the torque of the control ring

106 to the ring 103.

  The torque booster mechanism 107 comprises an inlet ring 108 integral with the control ring 106, an outlet retaining means 112 attached to the

  ring 103 and a locking ring 115.

  The inlet ring 108 is rotatably mounted on an intermediate outer circumference of the threaded ring 103. A number of rolling metal balls 109 are arranged between the opposed surfaces of the inlet ring 108 and the sleeve 104. The bushing Inlet 108 includes a number of protuberances 110 on its outer periphery for engagement with a number of grooves 111 defined in the inner wall of the control ring 106. In this manner, the inlet ring 108 is integral with the control ring 106 in

  being able to have a slight axial movement.

  The output retaining means 112 is attached to the outer periphery of a proximal portion of the threaded ring 103. The output retaining means 112 includes ball holders 113 provided, for example, in sixteen equidistant position peripherally. Each support

  113 supports a metal ball 114.

  The locking ring 115 is rotatably supported between the output retaining means 112 attached to the threaded ring 103 and an inclined portion defined on an intermediate periphery of the mandrel body 101. The locking ring 115 is constantly biased for pressure contact with the balls 114 of the output retaining means 112 attached to the threaded ring 103 by a coil spring 116 housed in the proximal portion of the cover 105. The coil spring 116 is compressed between a stop means 117 which is attached to the inner wall of the proximal portion of the cover 105 and a pressure plate 118. A number of metal balls 119 are arranged between the opposed surfaces of the ring

  blocking 115 and the pressure plate 118.

  Thus, the coil spring 116 constantly presses the pressure plate 118, the balls 119, the locking ring 115, the balls 114 held by the outlet retaining means 112, the inlet ring 108, the balls 109, the sleeve 104 and the threaded ring 103 axially against an inner wall peripheral to a

  front end of the control ring 106.

  As shown in FIG. 13, a leaf spring 121 is attached to the inner wall of the control plate 106 and faces the outer periphery of the lock ring 115. When the ring 115 can rotate in opposite directions, protrusion 122 formed on the leaf spring 121 engages a toothed surface 123 formed on the outer periphery of the locking ring 115 to rotate it in the same direction of the control ring 106. When the locking ring 115 is blocked against a rotation, this engagement is interrupted to allow the rotation of the ring of

command 106 alone.

  The engagement arrangement between the protuberance 122 of the leaf spring 121 and the toothed surface 123 is equivalent and performs a function similar to the arrangement between the toothed surface 30 and the elastic members 32 of the first embodiment which is However, the leaf spring 121 is not used to separate the locking ring 115 from the staggered portion 120 and the fifth embodiment rests, for this function, on the spring.

boudin 116.

  The locking ring 115 includes a pressure contact surface 124 on its inner periphery for

  a pressure contact with the step portion 120.

  This pressure contact surface 124 may have a

tapered shape.

  The manner in which mandrel 100 constructed according to the fifth embodiment functions to block

tool A will be described now.

  First, the tool A is inserted into the body 101 of the mandrel through the claws 102 which are kept wide open. Then, the control ring 106 is turned in the relatively tight direction of the tool

to the body 101 of the mandrel.

  During the rotation operation before the claws 102 come into contact with the tool A, only a minor resistance is applied to the threaded ring 103 and the locking ring 115 of the torque amplifier mechanism 107 is in a relatively free state. to the body 101 of the mandrel. Furthermore, since the locking ring 115 is connected to the control ring 106 by the leaf spring 121, the control ring 106, the inlet ring 108, the balls 114 of the holding means

  output 112 and the lock ring 115 rotate together.

  The rotation of the ring 103 which is at the same speed as the control ring 106 forms a fast forward for the rapid exit of the claws 102 to tighten the tool A. Subsequently, as shown in Figure 14, a load acts on the claws 102 of the mandrel when the latter contact and begin to tighten the tool A, thus producing a return of the claws 102. Then, the threaded ring 103 is axially withdrawn by the return, which removes, by the sleeve 104 and the balls 109, the inlet ring 108, the balls 114 held by the external retaining means 112 and the locking ring 115 of the torque amplifier mechanism 107, which have been axially pressed. As a result, the pressing contact surface 124 of the locking ring 115 comes into pressure contact with the stepped portion 120 of the mandrel body 101 and the leaf spring 121, to lock the locking ring 115 against rotation, undergoing a

sliding.

  When the locking ring 115 is locked against rotation, the balls 114 of the output retaining means 112 serve as a idle wheel to roll, with the rotation of the inlet ring 108, along the opposite face of the ring. This rolling movement produces a reduced rotation of the output retaining means 112, which reduces the rotation of the control ring 106 to rotate the threaded screw 103 with a high torque, and thus force the claws into said mandrel. tighten tool A firmly. When performing an operation using tool A, the leaf spring 121 forming the locking engagement serves to stop the relaxation due to the reactions of opposite rotations of mandrel 100 which is as in

  the preceding embodiments.

  When the tool A is released, the control ring 106 is turned in the relaxation direction relative to the body 101 of the mandrel. At the initial stage of the rotation operation, a high momentary torque occurs because the locking ring 115 of the torque amplifier mechanism 107 is locked against rotation. This facilitates the rotation of the threaded ring

103 in the direction of relaxation.

  After loosening, the resistance to rotation decreases and the coil spring 116 releases the locking ring 115 from the pressure contact, the locking ring being connected to the control ring 106 by the leaf spring 121. Then, command 106 and the

  Torque amplifier mechanism 107 rotate together.

  Rotation of the control ring 106 causes the threaded ring 103 to rotate at the same speed and thus the chuck claws 102 slide rapidly away from each other to release the tool A. When the tool A is maintained, as described above, the rotation of the control ring 106 is reduced by the rotating balls 114 which form part of the torque amplifier mechanism 107 for transmission to the output retaining means 112. Thus, a greater torque is obtained. high than that to turn the ring

  control 106 so that the tool A is firmly tightened.

  On the other hand, the resistance of the load is low and the control ring 106 and the respective components of the torque amplifier mechanism 107 can rotate together in opposite directions due to the action of the leaf spring 121 during the rotation operation performed. until the tool A is locked in position and during the rotation operation after its release. The claws 102 of the mandrel are quickly moved towards and away from each other by the threaded ring 103 to lock and release the tool A. Thus,

  this construction has excellent operability.

  For ease of operation, the relative rotation between the body 101 of the mandrel and the control ring 106 can be effected by opposite rotations of the mechanical drill or screwdriver.

  to which is attached the body 101 of the mandrel.

  This also applies to other embodiments. In the fifth embodiment, the torque enhancing mechanism 107 includes the rotating balls 114 to cause reduced rotation of the output retaining means 112. These balls 114 can

be replaced by gables.

  Such a construction will be described under

  form of a sixth embodiment.

  Fig. 15 shows a mandrel of the sixth embodiment. This mandrel has the same basic construction as that of the fifth embodiment and identical components have received the same figures of

  reference and their particularities will not be described.

  As illustrated, the torque amplifier mechanism 107 includes a number of bevel gears provided between the threaded ring 103 and the retaining means 112 attached thereto. The bevel gears 125 are engaged with a toothed surface 126 formed on the inlet ring 108 and a toothed surface 127 formed on the

  locking ring 115, respectively.

  With this construction, when the locking ring 115 is locked against rotation by the pressure contact with the stepped portion 120, the rotation of the inlet ring 108 causes a rotation and a rolling movement of the bevel gears 125. of the control ring 106 is reduced by this rolling movement for transmission to the output retaining means 112. Thus, the bevel gears 114 perform a function equivalent to that of the balls 114 of the fifth embodiment and this construction causes a high torque as in the

fourth embodiment.

Claims (12)

CLAIM I CAT I ONS   1. Chuck of the type having a number of claws mounted at the center of a front end of a chuck body to slide toward and away from each other, and a control ring peripherally mounted to the chuck body to be rotating in opposite directions to rotate a threaded ring to move the claws towards and away from each other, characterized in that it comprises: a locking means (22) disposed between said mandrel body and said claws to press them and locking them on said body by a reaction force which occurs when said claws block and a tool (A) and which releases them during the suppression of the reaction force, and an amplifier means of the torque (17) disposed between said locking means (22) and said control ring (18) for reducing the rotation of said control ring to emit an amplified torque for said threaded ring when said locking means is locked on said body of the mandrel, and transmit the rotation of said control ring to said threaded ring when   said locking means is released from said mandrel body.   2. mandrel according to claim 1, characterized in that the torque enhancing means comprises an inlet ring (21) freely mounted eccentrically in the control ring and integral with the threaded ring, said inlet ring and said means of blocking means (22) attachable to said mandrel body being axially arranged at said mandrel body, said inlet ring and said blocking means having mutually opposite surfaces defining cycloidal rolling grooves having different numbers of waves, and balls mounted between said grooves of rolling.   3. Mandrel according to claim 1, characterized in that the torque enhancing means comprises an outlet ring (20) fixed to the threaded ring and an inlet ring (21) supported relatively rotatably and eccentrically in said control ring, said output ring, said inlet ring and said blocking means (22) being arranged axially to said mandrel body, said inlet ring and said blocking means having mutually opposite surfaces defining cycloidal rolling grooves (23, 24) having different numbers of waves, balls (25) mounted between said race grooves, and power transmission balls mounted between said ring   input and said output ring.   4. Mandrel according to claim 1, characterized in that the torque amplifier means (47) comprises an inlet / outlet ring (48) freely mounted eccentrically in said control ring and secured to said threaded ring, said ring of inlet / outlet and said locking means (49) being lockable on said mandrel body having opposite inner and outer faces defining cycloidal gears having different numbers of teeth and taken with each other.   Mandrel according to claim 4, characterized in that the control ring comprises a tubular control section (51) which is formed on its inner intermediate wall eccentrically with respect to an axis of said mandrel body for rotatably supporting said ring entry / exit via a bearing (50) provided   peripherally to said tubular control section.   A mandrel according to claim 4, characterized in that the control ring comprises an inner wall formed eccentrically relative to the axis of said mandrel body for rotatably supporting said inlet / outlet ring (48). The chuck of claim 1, characterized in that said torque enhancing means (107) comprises an input ring (108) attached to said control ring (106), an output retaining means (112) disposed between said inlet ring and said blocking means being lockable to said mandrel body and attached to said threaded ring (103), said inlet ring and said output retaining means being axially arranged to said mandrel body and rotary means held by said output retaining means to be rotatable with relative movement between said ring   input and said locking means.   8. Chuck according to claim 7, characterized in that the rotary means comprises rollers (114).   9. Mandrel according to claim 7, characterized in that the rotary means comprises bevel gears (125), the inlet ring and the locking means defining a toothed surface (126, 127) for a   engagement with said bevel gears.   10. Mandrel according to any one of   Claims 1 to 4, 7 or 9, characterized in that the   locking means comprises pressure contact surfaces (58, 59) defined on a locking ring and   on the body of the mandrel to face each other.   11. Mandrel according to any one of   Claims 1 to 4, 7 or 9, characterized in that the   blocking means comprises tapered pressure contact surfaces (58, 59) defined on a ring of   locking and the body of the chuck to face each other.   12. Mandrel according to any one of   10 or 11, characterized in that the ring   blocking device defines a circumferential tooth surface   at its rear end face, said toothed surface being in engagement with an elastic member (33) secured to said control ring.