MXPA96004682A - Mandril with mechanism that limits the detorsion moment and inclined plan for tightening fi - Google Patents

Abstract

The present invention relates to a mandrel for releasably holding a tool, characterized in that it comprises: a main body, a plurality of longitudinal jaws that hold the tool, mounted for a movement in relation to the main body, each of the jaws is movable in relation to the main body parallel to a longitudinal axis of that jaw, the longitudinal axes of the jaws are synclinal in a direction distant along the body, a nut rotatably mounted on the body, the nut is also mounted for a movement axially limited relative to the body parallel to the distal direction, the nut engages threadably with each of the jaws to cause the jaws to move parallel to their longitudinal axes when the nut is rotated relative to the body or when the The nut moves axially in relation to the body parallel to the distant direction, a sleeve mounted on the e) a rotating manner on the body, a coupling limiting the torque torque operatively connected between the sleeve and the nut to cause the nut to rotate relative to the body with the sleeve in a direction of tightening the jaw until the jaws have begun to hold the tool and more than one predetermined torque torque must be applied to the sleeve to continue with the rotation of the nut in the clamping direction of the jaw, after which the coupling limiting the torque it is released, in such a way that the sleeve can continue with the rotation in the clamping direction of the clamp with the transmission of the at least partially reduced torque of the sleeve to the nut and consequently without further rotation of the nut in the clamp. tightening direction of the jaw, the predetermined threshold has a value greater than a minimum required to couple the sleeve and the nut before that the jaws clamp the tool and substantially less than a value required to finally tighten the tool for operation, a plurality of rolling cam follower elements disposed between a first substantially substantially facing face of the nut and a second substantially facing surface Distant that rotates in relation to the body with the sleeve, the cam follower elements are compressed axially between the first and second surfaces only after the jaws have begun to hold the tool and the nut moves relative to the body in the proximal direction in reaction to the force that holds the tool applied to the tool by the jaws, each of the cam follower elements roll, from their initial positions in relation to the first and second surfaces, along an arched segment of each one of the first and second surfaces when the follower elements of cam are compressed between the first and second surfaces and after the coupling limiting the torque is released and the sleeve continues with the rotation in the direction of tightening of the jaws in relation to the nut, at least one of the segments along which each of the cam follower elements rolls, are inclined with respect to each other of the segments from which that cam follower element rolls, in such a way that the cam follower elements drive the the nut to move in the direction distant in relation to the body, whereby the jaws are tightened further on the tool, and means to resiliently drive each of the elements of the cam follower to automatically return to its initial position in relation to at least one of the first and second surfaces when the cam follower elements are not compressed between the first and second surfaces, in wherein the second surface is disposed on an element of the mandrel that is rotatable in relation to the body, and wherein the mandrel further comprises: a rolling support structure disposed between a third, near-facing surface of the element and a fourth, distant-facing surface that is substantially fixed in relation to the body, the rolling support structure facilitates the rotation of the element in relation to the body

Description

MANDREL WITH MECHANISM THAT LIMITS THE MOMENT OF TORQUE AND INCLINED PLAN FOR THE FINAL TIGHTENING BACKGROUND OF THE INVENTION This invention relates to mandrels for releasably retaining tools (e.g., drill bits or drills for boring or boring) and more particularly with such mandrels which can be easily and simply operated to secure very securely a tool without the need for a wrench to tighten the mandrel on the tool. The mandrels with for imparting a final torque to the mandrel to securely hold a tool are well known. In as much, that such baboons have been highly successful, can have certain disadvantages. For example, the must be removed from the mandrel before the mandrel is rotated at high speed (for example in a drilling operation). The failure to separate the can unbalance the mandrel when it is rotated at high speed, or cause the to be thrown from the mandrel in a radial direction in a possibly unsafe manner. Although the must thus be removed frequently from the mandrel, the must be held in some way with the mandrel or it may be lost. Due to these disadvantages of the d mandrels, there has been an increased interest in recent years for mandrels which can be operated by hand without the need for (see, for example, the US patent of Huff et al. 125,673 and the North American patent of REF: 23315 Jordán et al. 5,215,317). Some of these ess chucks have been highly successful, but there is always room for additional improvements. For a mandrel to be acceptable it must be able to retain a tool very safely. The chuck jaws with relatively thin threads serve this purpose because the fine threads give an increased mechanical advantage. However, fine threads make a mandrel relatively slow to operate, whereby the mandrel becomes objectionable or even unacceptable to some users. A mandrel must also be as simple and easy to operate as possible. For example, it is preferable for the operator to be able to use a single, simple type of movement to tighten or loosen the mandrel. The mandrel must also be readjusted or reset reliably and automatically after each use, so that no further resetting or resetting of the operator is required. In view of the foregoing, it is an object of this invention to provide improved mandrels. It is another object of this invention to provide manually operated ess chucks, which do not require particularly thin jaw threads to hold a tool very securely, certainly more securely than conventional ess chucks with fine threads. It is still another object of this invention to provide manually operable ess chucks, which require the operator to perform a single direct movement, to tighten or loosen the chuck and which automatically resets or resets after each use in a highly efficient manner. trustworthy.

BRIEF DESCRIPTION OF THE INVENTION These and other objects of the invention are carried out in accordance with the principles of the invention by providing a mandrel with a mechanism that limits the torque between (1) the mandrel component (commonly a sleeve) which is rotated manually to tighten the mandrel on a tool and (2) the component of the mandrel (usually a nut) which is rotated by the sleeve to advance the jaws of the mandrel to hold the tool. When the jaws have been tightened in a tool to a predetermined degree, the resistance to the additional tightening causes the mechanism limiting the torque to be released. This allows the sleeve to rotate in relation to the nut. The initial tightening described above of the jaws on the tool also compresses a plurality of rolling cam follower elements (eg ball bearings) between a front facing surface of the nut and a distant front surface which rotates with the sleeve . When the sleeve rotates in relation to the nut, the elements of the cam follower roll along the segments of the surfaces between which the elements of the cam follower are compressed. These segments on at least one of the surfaces are inclined towards the other surface in the direction in which the elements of the cam follower roll, such that the cam follower elements urge the nut axially forward in relation to the cam follower. to the body of the mandrel as the elements of the cam follower roll. This forward movement of the nut drives the jaws further forward, thereby providing the final tightening of the chuck jaws on the tool. The rotation of the sleeve relative to the nut, especially during the operation of the cam follower elements described above, is preferably facilitated by the rolling support elements between the body of the mandrel and the rotating component in relation to the nut during the operation of the elements of the cam follower. These bearing or bearing elements can be ball bearings, but in a particularly preferred embodiment are substantially cylindrical roller bearings. When the mandrel is loosened again, the cam follower elements are no longer compressed axially between the surfaces along which they roll as described above. A relatively light spring is therefore effective for automatically restoring the cam follower elements to their initial positions in relation to the inclined surface segments along which they roll. Further features of the invention, its nature and various advantages will become more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an elevation view, partially in section, of an illustrative mandrel constructed in accordance with the principles of this invention. Fig. 2 is a partial sectional view taken along line 2-2 in Fig. 1. Fig. 3 is an elevation view of a part of the mandrel of Fig. 1, taken in the direction of arrows 3 in Figure 1. Figure 4 is a partial sectional view taken along line 4-4 in Figure 1. Figure 5 is a view similar to Figure 1 showing another illustrative embodiment of this invention. Figure 6 is an elevation view of certain parts of the apparatus shown in Figure 5. Figure 7 is a sectional view taken along line 7-7 in Figure 6. Figure 8 is a sectional view taken at along line 8-8 in figure 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in Figure 1, a mandrel 10 constructed in accordance with the principles of this invention has a main body 20 with a central longitudinal bore 22 and three auxiliary or complementary holes 24 spaced equidistantly from each other around the central longitudinal axis 12 of the mandrel. (Only one of the holes 24 is visible in Figure 1.) The proximal (further to the right) end of the hole 22 is adapted to receive an actuator for the mandrel (e.g., the end of the axle or shaft of a drill or manual or electric drill). The holes 24 are inclined to each other in the remote direction (to the left) and communicate with the distal portion of the hole 22. A longitudinal jaw 30 is disposed in each of the holes 24. Each of the jaws 30 can be received along its longitudinal axis 32. The jaws 30 are moved with reciprocating motion by the nut 40, which is rotatably mounted on the body 20 concentric with the shaft 12 and it threadably engages with each of the jaws 30. The rotation of the nut 40 relative to the body 20 consequently causes the jaws 30 to move in unison, either towards or from the shaft 12, depending on the direction of rotation of the nut. The nut 40 is rotated by rotation of the front annular sleeve 50 which (like the nut 40) is rotatably mounted on the body 20 concentric with the shaft 12. In general, the torque is transmitted from the sleeve 50 to the nut 40 by the ring 60 which is disposed between the elements 40 and 50 concentric with the shaft 12. The construction and operation of the ring 60 is described in more detail below. Behind the nut 40 (in the proximal direction) are a plurality of ball bearings 70, spaced apart in an annular array, concentric with the shaft 12 when being arranged in equally spaced openings sn ring 72 of the box (see also figure 4). In the particular embodiment shown in the drawings, there are four balls 70 equally spaced apart about the axis 12. Behind the ball bearings 70 (again in the proximal direction) is an annular cam ring 80, which is concentric with the shaft 12. The cam ring 80, which is another part that is described in more detail below, is restricted to rotating with the sleeve 50 at all times by the projections 52 on the sleeve, which project radially inwardly. to the coupling notches 82 (FIG. 3) in the cam ring 80. Behind the cam ring 80 (in the proximal direction) is another ball bearing structure which includes a plurality of ball bearings 90 spaced apart in an annular array concentric with the shaft 12 by the ring 92 of the box. (The ring 92 of the box is optional and can be omitted if desired.) In the proximal direction the ball bearings 90 rest on an annular guide ring 100 of the bearing on the body 20. A rear sleeve 110 is secured to the back of the body 20. The nose piece 120 is secured on the distal end of the body 20 and by this retains the elements such as, 50 and 60 on the body 20. However, limited movement of the nut 40 parallel to the shaft 12 is allowed. The construction of the ring 60 and associated parts is shown in more detail in Figure 2. The ring 60 has a pair of projections 62 extending radially and axially, diametrically opposed, each of which projects radially inwardly to a coupling channel 42 extending axially in the nut 40. The nut 40 and the ring are thereby restricted from rotating with each other at all times. The ring 60 also has a pair of projections 64 that extend radially and axially, diametrically opposed, which project radially outwardly from its outer surface. Each of the projections 64 has a substantially radial face 64b and a generally opposite inclined face 64a. Radially within each of the projections 64 the ring 60 has a circumferentially and axially extending opening 66, which allows the adjacent projection 64 to move radially inward under certain conditions as described below. The projections 64 on the ring 60 are intertwined with the projections 54 extending radially and axially on the sleeve 50. The projections 54 are diametrically opposed to each other and project radially inwardly from the sleeve. Like the projections 64, each of the projections 54 has a substantially radial face 54b and a generally opposite inclined face 54a. When the sleeve 50 is rotated in the direction indicated by the arrow 56 in Figure 2 (which is the direction of rotation of the sleeve required to tighten the jaws 30 on a tool), the sleeve 50 can rotate in relation to the nut 40 until the inclined surfaces 54a of the projections 54 come into contact with the inclined surfaces 64a of the projections 64. After this, the prolonged rotation of the sleeve 50 in the direction 56 causes the ring 60 and consequently the nut 40 turn at address 56 This causes the jaws 30 to move in the distal direction until the tool is held by the jaws. When the jaws 30 come into contact with the tool, it becomes increasingly difficult to continue the rotation of the nut 40 in the direction 56 as the force to hold the tool, exerted by the jaws, increases. It should also be noted that another consequence of the clamping force exerted by the jaws 30 on the tool is a reaction force which causes the nut 40 to move in the proximal direction and apply a compression force to the balls 70, the cam ring 80, and balls 90. When the manual torque, which must be applied to the sleeve 50 to continue the rotation of the nut 40 in the direction 56, reaches a predetermined threshold torque, the ring 60 it flexes inwards in the vicinity of the projections 64 and the openings 66, whereby each of the projections 54 is allowed to pass to the projection 64 with which it was originally in contact. The structure thus described therefore acts as a mechanism limiting the torque, of the detent type. When the retainer of this mechanism limiting the torque is released, the sleeve 50 can continue its rotation in the direction 56 without further rotating the ring 60 or the nut 40. The cam ring 80, however, continues with its rotation in the direction 56. And because the balls 70 have been compressed between the nut 40 and the cam ring 80, the balls 70 begin to roll along the mutually opposite faces of the non-rotating nut 40 and the ring 80 of rotating cam. As the balls 70 roll in this manner, they lead to the ring 72 of the box with them. In particular, it will be noted that during this phase of the operation, the ring 72 of the box rotates about the axis 12 in the direction 56 at half the speed at which the sleeve 50 and the cam ring 80 rotate. The springs 130, which, as best seen in FIG. 4, extend between the sleeve 50 and the ring 72 of the box, are stretched (that is, they are placed in increased tension) by this rotation of the sleeve 50 in relation to the 72 ring of the box. As shown in Figure 3, the surface of the cam ring 80 along which the balls 70 roll as described above, has four arcuate channels 84, spaced apart around the cam ring. Each of the balls 70 rolls in a respective channel of the channels 84. These channels have transverse sections which are concave to complement the convex outer surfaces of the balls 70. Each of the channels 84 gradually becomes less deep in the opposite direction 56. Therefore, as the cam ring 80 rotates in relation to the nut 40 in the direction 56, each ball 70 rotates from the deepest end 84a of the associated channel towards the shallow end 84b of that channel . The cam ring 80 thereby urges the balls 70 to move in the distal direction. The balls 70 in turn drive the nut 40 and the jaws 30 to move in the distal direction, whereby the grip of the jaws 30 on the tool which is retained by the mandrel is significantly tightened. The end shallow end 84b of each channel 84 may be slightly deeper than the immediately adjacent portion of that channel, such that the associated ball 70 has a tendency to remain at the shallow end of the channel until the mandrel is loosened deliberately by rotating the sleeve 50 opposite the direction 56 as described in detail below. From the foregoing it will be seen that the bottom of each channel 84 is a ramp, inclined plane or cam surface, with the associated ball 70 as a rolling follower to transmit its axial movement as a follower to the nut 40 and consequently to the jaws 30. The slope of each channel 84 is extremely gradual, in such a way that a great mechanical advantage of the rotation of the sleeve 50 in relation to the nut during the operation of the cam ring 80 is developed in the manner described above. It will be noted that each channel 84 subtends an angle of approximately 70 °. Accordingly, the sleeve rotates in the direction 56 by an angle of approximately 140 ° in order to roll the balls 70 from the deepest ends 84a of the channels 84 to the shallower ends 84b of the channels. Because the protrusions 54 are approximately 180 ° apart on the sleeve 50 and the projections 64 are approximately 180 ° apart on the ring 60, after the protrusions 54 and 64 pass each other to initiate the rolling of the balls 70, the balls reach the shallow ends 84b of the channels 84 before the projections 54 reattach with the projections 64. When it is desired to loosen the mandrel and remove the tool retained by the jaws 30, the sleeve 50 is rotated in the opposite direction to the direction 56. This causes the balls 70 to roll back from the shallow ends 84b of the channels 84 to the deeper ends 84a of those channels, whereby some of the pressure of the jaws 30 on the tool is relieved. . As the balls 70 approach the deepest ends of the channels 84, the radial faces 54b of the projections 54 come into contact with the radial faces 64b of the projections 64. As a result of this contact, the prolonged rotation sleeve 50 in the opposite direction to the direction 56 causes the ring 67 and the nut 40 to rotate in the opposite direction to the direction 56. This retracts the jaws 30 and releases the tool from the mandrel. When the pressure of the jaws on the tool is sufficiently relieved, the elements 70, 80 and 90 are no longer compressed between the nut 40 and the guide ring 100 of the bearing. This allows the springs 130 (which act in tension in the circumferential direction between the sleeve 50 and the ball box 72) to automatically rotate the ball box 72 (if necessary) in relation to the elements 50 and 80 in such a way that the balls 70 return to the deeper ends 84a of the channels 84. Thus the mandrel is fully and reliably readjusted or reset after each use, so that it is always ready for the next use. Because only the springs 130 are required to rotate the ring 72 of the box when there is substantially no compressive force on the balls 70, the force of the springs 130 can be relatively small, so that even when fully stretched , they do not tend to significantly loosen the tight mandrel by strongly urging the balls 70 to roll from the shallow ends 84b of the channels 84 to the deepest ends 84a of those channels. When it is desired to immediately attach a tool to the mandrel 50, the sleeve 50 is rotated again in the direction 56. The first nearly 180 ° of this rotation may be required to cause the inclined surfaces 54a of the projections 54 to be re-engaged with the inclined surfaces 64a of the projections 64. (The balls 70 do not roll during this relative rotation between the sleeve 50 and the nut 40 because the balls 70 are not then compressed between the nut and the ring 80.) After this, the prolonged rotation of the sleeve 50 in the direction 56 rotates the ring 60 and the nut 40 in the same direction, whereby the jaws 30 are moved in the direction away from the tool to be clamped. Then the operation of the mandrel continues as previously described above. Among the advantages of the mandrel 10 is that the sleeve 50 is substantially uncoupled from the nut 40 while the mandrel is tightened on a tool. The inertia of the nut 40 is reduced by this. This allows the chuck capacity to remain strong by resisting vibration and accelerations in the longitudinal and circumferential directions. Although the various components of the mandrel 10 can be made of any suitable material, the particularly preferred materials for the sleeve 50 and the ring are nylon 60 and acetal, respectively. It will be understood that the foregoing is only illustrative of the principles of this invention and that various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. For example, the numbers of such components as projections 54, projections 64, balls 70 and channels 84 can be varied as desired. If the mandrel is mounted on a tool having a screw lock, the sleeve 50 can extend further to the rear end and the separate back sleeve 110 can be removed. As another example of the possible modifications, the channels 84 can be moved from the distant surface of the ring 80 to the opposite proximal surface of the nut 40 or such inclined channels can be provided on both of these surfaces. Radially extending roller bearings can be used in place of the balls 70 with appropriate modification of the shape of the channels 84 to accept such rollers instead of balls. Instead of having projections 64 that deviate inwardly to pass the projections 54, the projections 54 could be bent outwards to allow such a step. Instead of having retaining surfaces 54b and 64b which are positioned to engage with each other before the sleeve 50 is rotated back to the position in which the associated inclined surfaces 54a and 64a face each other, the projections 54 and 64 could be formed in such a way that they easily pass each other when the sleeve 50 is rotated in the loosening direction and other the retaining surfaces (such as the surfaces 54b and 64b but with at least different angular positions and possibly also different axial positions) could be coupled together to prevent further rotation of the sleeve 50 in a direction opposite to the direction 56 without loosening rotation of the similar mandrel of the ring 60 and the nut 40. Certainly, these alternative retaining surfaces could be located on elements other than 50 and 60 if desired. As yet another example of possible modifications, the operation limiting the torque provided between the sleeve 50 and the ring 60 could alternatively be provided between the ring 60 and the nut 40. Instead of the mechanism limiting the torque of type releasable retainer shown in the drawings, the mechanism limiting the torque could be of the friction type. Such a mechanism limiting the friction type torque takes advantage of the fact that the static friction between two surfaces is greater than the sliding friction between those surfaces under otherwise similar conditions. Thus the static friction between the elements 50 and 60 would be used to transmit the torque from the sleeve 50 to the ring until a threshold torque is reached, at which point the reduced sliding friction would allow the sleeve 50 to rotate in relationship to ring 60. It will be noted that the torque limiting mechanisms employed in accordance with this invention are preferably "passive" in the sense that they do not store energy to any significant degree. This is true for the mechanism that limits the torque of the releasable retainer type shown and the mechanism limiting the torque of the alternative friction type described above. These mechanisms that limit the torque passive transmit torque torque applied to them, but unlike a spring, for example, do not store energy significantly which could cause the mandrel to loosen after it has been tightened on a tool and while the tool is used. An alternative embodiment of this invention is shown in Figures 5-8. The construction and operation of the mandrel 10 'shown in these figures is similar to the mandrel 10. Therefore,, the same reference numbers are used in Figures 5-8 for the parts that are the same or similar parts shown in Figures 1-4. In general it will not be necessary to describe these parts or their operation again with reference to Figures 5-8 because a full description has already been provided in relation to Figures 1-4. The main difference between the mandrel 10 of FIGS. 1-4 and the mandrel 10 'of FIGS. 5-8 is that substantially cylindrical roller bearings 90' (instead of ball bearings 90) are used between the ring 80 and the guide ring 100 of the bearing. Roller bearings 90 '(sometimes called needle bearings) have a number of advantages over ball bearings in this context. For example, because the roller bearings have much more surface support area than the balls of the same diameter, the diameter of the rollers 90 'can be made much smaller than the diameter of the balls 90 for the same or even greater capacity of support. The ability to use rollers 90 'of smaller diameter helps to shorten the axial length of the mandrel. This is particularly important in a mandrel design that otherwise tends to be axially elongated by an axial succession of components associated with the torque limiting mechanism, the cam and the cam follower mechanism, etc.

Figure 6 shows that a plurality of roller bearings 90 'are arranged in an annular array that is substantially concentric with the central longitudinal axis 12 of the mandrel. The longitudinal axis of each roller bearing 90 'extends axially outwardly from the shaft 12. The rollers 90' are rotatably disposed in the openings 94 'in an annular box member 92' (see Figures 6-8). The rollers 90 'can be made of steel, while the box member 92' can be made of nylon. Each side of each opening 94 'that is parallel to the longitudinal axis of the roller 90' that is disposed in that opening has two projections 96 'projecting inward to retain the roller in the opening. All the shoulders 96 'in an opening are parallel to the longitudinal axis of the roller in that opening. The two shoulders 96 'on the same side of an opening are laterally spaced from each other, each of these two shoulders being adjacent to a respective surface of the two substantially flat surfaces of the box member 92'. Another difference between the mandrel 10 and the mandrel 10 'is that the mandrel 'has a structure 200 removable in the nose 120 of the mandrel. The structure 200 includes an outer plastic ring 210 concentric with the shaft 12, and a ring 220 of integral internal rubber and concentric with the ring 210. The ring 210 is releasably attached to the nose piece 120 commonly of mandrel metal . The ring 220 has a central opening 222 through which the rod of a tool such as a drill bit or drill bit or drill can be inserted into the mandrel. If the shank of the tool is larger than the opening 222, the rubber ring 220 deforms to allow the tool shank to enter. Assuming that the tool shank is at least as large as the opening 222, the ring 220 retains and centers the tool on the mandrel before the mandrel jaws are tightened on the tool and after the tool has been released from the tool. the jaws. Also, during the use of a sufficiently large tool, the ring 220 prevents debris from entering the mandrel around the tool shank. If the structure 200 wears or is damaged, it can be ejected from the nose piece 120 and replaced with a new similar structure 200. It will be understood that the embodiment shown in Figures 5-8 is again illustrative only of the principles of this invention. For example, the modifications of the classes mentioned above after the discussion of Figures 1-4 are again applicable to the embodiment shown in the figures -8. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates. Having described the invention as above, property is claimed as contained in the following

Claims (10)

1. Claims 1. A mandrel for releasably holding a tool, characterized in that it comprises: a main body; a plurality of longitudinal jaws that hold the tool, mounted for a movement in relation to the main body, each of the jaws is movable relative to the main body parallel to a longitudinal axis of that jaw, the longitudinal axes of the jaws are synclinal in a direction distant along the body; a nut mounted rotatably on the body, the nut is also mounted for limited axial movement relative to the body parallel to the distal direction, the nut is threadably engaged with each of the jaws to cause the jaws to move parallel to their longitudinal axes when the nut is rotated relative to the body or when the nut moves axially relative to the body parallel to the distal direction; a sleeve mounted rotatably on the body; a coupling limiting the torque torque operatively connected between the sleeve and the nut to cause the nut to rotate relative to the body with the sleeve in a clamping direction of the jaw until the jaws have begun to hold the tool and more than one predetermined threshold torque must be applied to the sleeve to continue the rotation of the nut in the clamping direction of the jaw, after which the coupling limiting the torque is released, so that the sleeve can continue to rotate in the clamping direction of the jaw with the transmission of the at least partially reduced torque of the sleeve to the nut and consequently without further rotation of the nut in the clamping direction of the jaw, the predetermined threshold has a value greater than a minimum required to couple the sleeve and the nut before the jaws grip the tool ient and substantially less than a value required to finally tighten the tool for its operation; a plurality of rolling cam follower elements disposed between a first substantially substantially facing face of the nut and a second substantially distant facing surface rotating in relation to the body with the sleeve, the cam follower elements are compressed axially between the legs. first and second surfaces only after the jaws have begun to hold the tool and the nut moves relative to the body in the proximal direction in reaction to the force that holds the tool applied to the tool by the jaws, each of the elements of cam follower roll, from their initial positions in relation to the first and second surfaces, along an arcuate segment of each of the first and second surfaces when the cam follower elements are compressed between the first and second surfaces and after the coupling limiting the torque has been released and the sleeve continues with the rotation in the direction of tightening of the jaws in relation to the nut, at least one of the segments along which each of the elements of cam follower wheels, are tilted with respect to each other of the segments along which the cam follower element rolls, such that the cam follower elements urge the nut to move in the distal direction relative to the body, whereby the jaws are tightened further on the tool; and means for resiliently driving each of the cam follower elements to automatically return to their initial position in relation to at least one of the first and second surfaces when the cam follower elements are not compressed between the first ones, and second surfaces, wherein the second surface is disposed on an element of the mandrel that is rotatable relative to the body, and wherein the mandrel further comprises: a rolling support structure disposed between a third surface of the element's near front and a fourth Distant front surface that is substantially fixed in relation to the body, the rolling support structure facilitates the rotation of the element in relation to the body.
2. 2. The apparatus defined in claim 1, characterized in that the rolling support structure comprises a plurality of rolling support elements arranged in an annular array substantially concentric with a mandrel axis about which the nut rotates concentrically.
3. 3. The apparatus defined in claim 2, characterized in that the rolling support elements consist of balls.
4. 4. The apparatus defined in claim 2, characterized in that the rolling support elements are substantially cylindrical rollers, each of which has a longitudinal axis extending substantially radially outwardly from the axis of the mandrel.
5. 5. A mandrel for releasably holding a tool, characterized in that it comprises: a body structure having a longitudinal axis; a plurality of longitudinal jaws holding the tool mounted in relation to the body structure such that the longitudinal axes of the jaws are inclined towards the longitudinal axis of the body structure in a direction distant along the longitudinal axis of the body. body structure, each of the jaws is movable relative to the body structure substantially parallel to the longitudinal axis of the jaw; an alternative movement structure of the jaw, mounted on the structure of the body, at least part of the reciprocating structure of the jaw is rotatable in relation to the structure of the body around the longitudinal axis of the body structure, with the in order to move the jaws in relation to the structure of the body substantially parallel to the respective longitudinal axes of the jaws; and a plurality of substantially cylindrical roller support elements disposed between a face surface substantially remote from the body structure and a face surface substantially proximal to the rotatable part of the jaw reciprocating structure, the support elements of the jaw. Roller facilitate the rotation of the rotating part of the reciprocating structure of the jaw in relation to the body structure.
6. 6. The apparatus defined in claim 5, characterized in that each of the roller elements has a longitudinal axis which is substantially radial to the longitudinal axis of the body structure.
7. 7. The apparatus defined in claim 6, characterized in that the annular support elements are arranged in an annular array which is substantially concentric with the longitudinal axis of the body structure. • The apparatus defined in claim 5, characterized in that the rotatable part of the reciprocating structure of the jaw includes: a nut portion threadably engaged with the jaws, such that rotation of the nut portion around the body structure causes the jaws to move in relation to the structure of the body substantially parallel to the respective longitudinal axes of the jaws; and a reciprocating portion of the nut for reciprocating the nut substantially parallel to the longitudinal axis of the body structure and thereby moving the jaws further relative to the body structure substantially parallel to the respective longitudinal axes of the body. the jaws. 9. The apparatus defined in claim 8, characterized in that the reciprocating portion of the nut is selectively rotatable relative to the nut portion and wherein the reciprocating portion of the nut alternately reciprocates the nut portion. during the rotation of the reciprocating portion of the nut in a loop. tion to the nut portion. 10. The apparatus defined in claim 9, characterized in that the proximal facing surface is disposed over the reciprocating portion of the nut.