JPH01140902A - Attachment, bite holder and fixture being applied to tapered end face of bite and particularly having tapered shunk of no.7/24 cone - Google Patents

Abstract

PURPOSE: To particularly and reliably install a No. 7/24 conical taper shank on a main spindle by assembling a front part having an inserting taper and a flange to the main spindle through a slider, and pressing the taper to a locking position in the main spindle by an elastic device. CONSTITUTION: A pressure adjusting means 7 is screwed in a hole 10 of a taper 1 inserted into a main spindle 2 of an installing device, and an elastic device 6 is inserted, and next, a front part 3 having a flange 4 is inserted through packing 16 and a cylindrical pin 19 in a groove 17. Next, a slider 5 is inserted from the rear end of the taper 1 by interposing packing 24 and 26, and is screwed in a screw groove 23, and a screw 20 is locked and assembled in a groove 18. Therefore, a push of the flange 4 against the main spindle 2 and a pressure push of the taper 1 are reliably performed, and stress from the main spindle 2 can be transmitted in a work process.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to the area of machine tool accessories in numerical control, processing centers, flexible organizations and workshops, and for machine tools of this type with automatic or manual tool changers.
The object is a mounting device that is applied to the taper and end face of attachments, tool holders, and tool tools, and in particular has a taper shank of ≠7724 conical shape.

Currently, the fixation or attachment of tool attachments to the spindles of numerically controlled milling and boring machines in processing centers or flexible tissues and workshops is generally achieved using taper shanks, typically with a 7/24 taper. There is. These installations and fixations have been satisfactory to date and continue to be so for certain processing operations.

With the advent of 7724 taper machining centers, often with special flanges for automatic tool change and a truncated rear, the conventional 7724 taper with a rear thread for fixation by a threaded stay and a simple flange has been modified. It has arrived.

Most of the machine spindles currently in production are for mounting tools with a 7/24 taper as well as flanges conforming to normal standards, and for some manufacturers there are some with very special flanges. The machine still exists.

Although the known fixing methods described above are completely unsatisfactory for certain applications, there has been an increase in output and major performance of machines and processing centers, as well as significant breakthroughs brought about in cutting tools and inserts. Due to modern advances, the fixation of the taper within the spindle is no longer compatible with the advances achieved by the machine and the tool performance, as the developing power of the machine and the resultant force withstood by the tool cannot be transmitted to the location of the taper. It's a big handicap.

In fact, the critical point or weakness of the fixation in reality is very often at the exit of the spindle, and this is the point of weakness of all tool holders or tools, which must adhere to a certain diameter of the tool. This is the long axis of the taper tip connected by a cylindrical portion shorter than the flange 9'. The same problem occurs when fixing the No. 7724 taper tool to the lathe, but it is not so definitive that it is a side repair.

It has also been proposed to use a cylindrical shank that presses against the front surface of the spindle to secure the tool. This method certainly makes it possible to solve the problem of perfect contact between surfaces, but requires modification of the main axis of the machine. Moreover, in some cases the weight of the critical tool risks correcting its alignment with respect to the spindle. Furthermore, the positioning of the tool changer must be performed with extremely tight tolerances in all directions in order to ensure perfect alignment of the axis of the spindle and the tool holder.

Similarly, if high performance is to be achieved, it is proposed that a specific gauge be used for each spindle to achieve a monoblock standard taper in order to obtain simultaneous taper of the spindle and end face. Ta.

However, this type of implementation results in extremely high costs;
Mass production requires manufacturing tolerances that are difficult to maintain. moreover,
The tool obtained in this way is absolutely specific for a particular spindle and cannot be interchanged with tools for other spindles or other machines, hence this specific example. is only useful for answering specific questions.

The present invention aims to alleviate these drawbacks.

In fact, the present invention is directed to a mounting device with a taper shank, in particular a 7/24 cone, which is applied to the taper and end face of an attachment, tool holder, and tool tool. Front, taper and front assembly slider with a flange centered in the taper and pressed against the spindle surface, pressurized between the taper and the front, pressing the taper into the locking position within the spindle. an elastic device, and adjusting means for said pressure device.

The invention will be better understood from the following description, which refers to some preferred embodiments given by way of non-limiting example and with reference to the accompanying drawings, in which: FIG.

1 According to the invention, by way of example more specifically
1 The mounting device is equipped with a #key flange 4 centered within the main spindle 2.1 and pressed against the end face of the main spindle 2. The front part 3, the taper 1 and the slider 5 for assembling the front part 3, the taper 1 in the locking position in the main shaft 2, which is compressively mounted between the taper 1 and the front part 3.
an elastic device 6 for pressing, and adjustment means 7 for the pressing device
Consisted of.

Taper 1 has a length compressed by a sufficient number of millimeters on both sides compared to the current taper, and has a hole of 1G.
with two concentric holes 8 and 9 centering the front part 3 of the hole 10, which has a smaller diameter than the hole 9 and is applied to the receiving chamber of the elastic device 6, which The slider 5 is provided with an annular sealing 26 and presses against the rear side of the taper 1 with the support surface 27, further extending the taper 1 towards the flange 4 of the front part 3. The surface is provided with a circular groove 15 for receiving the annular packing 16.

The length of the taper 1, which has a length reduced by a tenth of a millimeter compared to the current taper, results in the taper 1 fixed in the main shaft 2 of the machine having a front surface slightly set back from the front surface of the main shaft 2. There is. Furthermore, when the taper 1 is in that position, the rear face is also slightly closer to the front face of the main shaft 2 relative to known tapers.

The front part 3 with the flange 4 is wider than the current flange, and therefore the length of the cylindrical part connected to the flange is shortened.The front part 3 is equipped with a flange 4, which shortens the distance between the front surface that presses against the end surface of the main shaft 2 and the rear surface of the flange. and the corresponding six eight of taper 1
and 9, respectively, and centered within the taper 1 using the slider 5 against the action of the elastic device 6. tightened inside.

The flange 4 is provided in its center with a V-shaped circumference 12 for receiving the arm of the tool changer. The flange 4 further comprises two arms 13 which receive drive grooves 14 of the main shaft.

The holes 8- and 9 of the taper 1 and the concentric cylindrical portions 8' and 9' exhibit tight tolerances that allow billions of axial movements; It can also be used for machines without a device, ie, manually installed machines.

The cylindrical part 9' of the front part 3 furthermore has a hole 9 of the taper 1 on the one hand.
with a key or cylindrical pin 19 rotatably interlocked between the taper 1 and the part 3 inserted in corresponding grooves of the front part 3 and two grooves 17 and 18 receiving the cap screw 20 of the front part 3 on the other hand. There is.

This is adjusted via means 7 which take the form of several springs extending in parallel in a circular chamber defined by the slider 5 or more advantageously in the form of a threaded sleeve working in conjunction with the threads of the hydraulic or pneumatic part. The sleeve is a compression screw 21
6 means 7, which are fixed in the position of use by means of a screw, allow a precise adjustment of the compression of the device 6, and a compression screw 21 ensures that the adjustment is maintained.

The fixing screw 20 of the front part 3 is inserted into the groove 1 of the cylindrical part 9' of said part 3.
8 and under the continuous pressure exerted by the device 6, the exchange of the slider 5 is intended to avoid accidental disassembly of the part 3 of the taper 1 in some cases.

The front part 3 further comprises two concentric holes 22 and 23, one of which 23 is threaded and adapted to receive the threaded tip of the slider 5.

The other hole 22 is smooth and allows the annular packing 24 housed in the corresponding circular groove of said slider 5 to be inserted into one of the cooperating parts 13.
The device is fixed in the use position via a radial screw 25 inserted into the front part 3 at one height. This screw 25 therefore makes it possible to realize the fixation of the slider 5 both in terms of its insertion depth and rotationally in the part 3.

The front part 3 can be embodied for milling cutters, current male or female modular devices, flanges, boring bars, boring heads, special tools as well as errata spindles, stands.

At the position where the device of the present invention is installed in the main shaft 2, a slider 5 is used to create a taper between the front surface of the main shaft 2 and the rear surface of the flange 4, against the action of the device 6, before tightening with the slider of the machine. There is a space in 1 that can be adjusted by tightening part 3 (Fig. 1). After fixing this space with slider 5, the space a can be adjusted by tightening with a mechanical slider. It is provided between the corresponding surface of the taper 1 for forming and the support surface 27. During this fixing, the slider 5 pulls the front part 3 against the action of the device 6 by means of the rear surface of the flange 4 which opposes the main shaft 2 during pressing by the action of the slider of the machine, and the reaction of the compression of the device 6 is the result. as spindle 2
It will have an additional pressing force of the taper 1 in its accommodation chamber.

The groove for fixing by means of a threaded slider is provided with a cylindrical portion.

In a known manner, the device of the present invention is capable of directing lubricating oil into a groove 30 communicating with a passage or opening in the vicinity of the cutting tool, unlike current external spindle lubrication systems that require a specific lubrication system. A lubrication circuit passing through the slider 5 in the form of a hole 29, for example 2 facing diametrically of the flange 4
A lubricant intake from the front side of the spindle 2 cooperating with the corresponding surface of the flange 4 can be provided with a pocket 31, said pocket 31 being coupled with the cutting process in the manner described above. In order to do so, it communicates with the eraser 30 using a passage 32.

Of course, in this case, the slider 5 used has no holes.

The annular packings 16, 24 and 26 are intended to completely prevent impurities and lubricating oil from entering the interior of the device.

The device of the present invention is installed as follows.

Into the hole 10 of the taper 1 the compression adjustment means 7 of the device 6 are inserted by screwing, then the device 6 is inserted, the annular packing 16 is inserted into the circular groove 15 on the front side of the taper 1, and then the Part 3 is inserted into taper 1 with its cylindrical parts 8' and 9' centered in corresponding 68 and 9.

An annular packing 24 in the corresponding receiving chamber on the slider 5
and 26, this slider is inserted from the rear side of the taper 1 and screwed into the part 3 via its thread groove 23.

The slider 5 is then tightened until the thickness of the space is obtained;
This space is required after mounting and tightening the device in the main shaft 2 of the machine and can be measured using a key. The screw 20 is then inserted into a corresponding hole 18 in order to prevent any accidental disassembly of the device formed by the taper 1 and the front part 3 when unscrewing the slider 5. screw 2
To position 0, use the key or 4, cylindrical bottle 19 and clear 17.
Due to the cooperation with the groove 18, it is always completely secured facing the groove 18.

According to the mounting method of the present invention, it is possible to reliably press the flange 4 against the main shaft 2 and press the taper 1 into the taper of the main shaft 2 to the fixed position of the device via the slider of the machine. In this way, all the stresses developed by the spindle 2 during the machining process are due to the pressing of the flange on the spindle 2 and the tenon 1 of the spindle 2 cooperating with the groove 13 of the flange 4.
4 is transmitted thanks to the pressing pressure of the taper 1 into the main shaft 2 and the pressing of the flange 4 onto the main shaft 2 by the pulling force on the slider 5 due to the pull and drive of the machine, which is realized directly with the help of the Ru.

This direct pressing of the front part 3 onto the front face of the main shaft 2 makes it possible to utilize the full power of the machine. The reason is that generally all weak points that cause vibration have been removed, and the taper 1
now serves only as a centering of the part 3, which centering is achieved via the clamping force of the device 6 and the pulling device of the machine on the surface 8.
9 and 8'.

This is a lick that is supplemented by the cooperation between 9′.

As shown in Figures 3 to 7 of the accompanying drawings, the front part 3 can have a wide variety of configurations.

FIG. 3 thus represents the module assembly by hole, and all other module equipment can be left in place.

FIG. 4 shows a male module device, also given as a non-limiting example.

FIG. 5 shows an example in which the front part 3 is used as a support member for a price flange fixed using an axial circumferential screw. In this case, as well, as shown in FIG. The device can have a shorter length, especially when using a milling cutter tenon positioned at the front as shown in FIG.

FIG. 7 shows a monobloc claw-type milling cutter with part 3, which type of milling cutter can also be fixed using screws and a central core.

FIG. 8 shows a modified embodiment of the invention, in which the front 3
The cylindrical part 9' of the front part 3 in the taper 1 has a fixing screw 20
It is provided with a circular groove 33 cooperating with.

In this embodiment, groove 33 replaces grooves 17 and 18 and key or cylindrical pin 19.

In this way, the tightening by pressing the taper 1 against the inner tapered wall of the main shaft 2 still allows a light rotation of the part 3 inside the taper 1 when installing the device in the main shaft of a machine with the device. and makes it possible to drive the part 3 by means of a drive groove 14 cooperating with the groove 13, the taper 1 ensuring the centering of the part 3 with respect to the main axis 2.

According to another characteristic of the invention, the bore 8 of the taper 1 is furthermore provided with a cylindrical groove for the receiving chamber of an auxiliary annular packing 34.

This packing 34 makes it possible to ensure better tightness between the part 3 and the taper 1.

FIG. 9 and FIG. 12 show two examples in which the device of the present invention is applied to a tool holder for a lathe and a turning center.

For this purpose, according to a first embodiment of the invention according to FIG. 9, the device is mounted with its taper 1 in a fixed frame 35 with the flange 4 leaning against the front side of said frame 35,
The frame is a means 3 for gripping and tightening the tip of the slider 5.
6 at the level of the slider 5, the means being located at the level of the slider 5.
and an elastic ring 46 near its tip, which extends perpendicularly or at an acute angle to the axis of the taper 1, and is installed in the blind housing chamber 37.

The means 36 for gripping and tightening the tip of the slider 5 is composed of two pistons 38 and 39, which slide within the storage chamber 37 and are approached or tightened using a screw 40 with a reverse thread groove. It is attached so that separation movement can be performed while restricting movement via the elastic ring 46. These two pistons 38 and 39 on the one hand face the gripping contour 28 of the slider 5 on the side facing in the direction of the taper 1.
each comprising a hawk 41, 42 for engaging within the
On the other hand, on the side opposite the slider 5, a recess 43 is formed for receiving the ejection device 44 of the tapered shank attachment device and extends into this device 4445.

According to a variant embodiment of the invention, which is not shown in the accompanying figures, the movement of the pistons 38 and 39 toward or away from each other within the receiving chamber 37 also cooperates with the unscrewing of one of the pistons 38 and the unscrewing of the other piston 39. It can also be realized using a simple screw which presses with its head into the bogget of the screw. The free end of the screw head, during unscrewing, abuts against an elastic ring housed in a pocket above the head.

The ejection device 44 has a screw 40 at its tip surrounding the screw 40.
It has a rectangular cross-section 47 which connects to a cylindrical guide 49 in the hole 45 of the frame 35. This cylindrical part 49 is extended on the one hand by a cylindrical cross-section shaft 50 which opens into the hole 45 and is equipped with an elastic ring 51 at this height, and on the other hand by means of an elastic ring 54 that extends into the hole 45.
5 is provided with a series of springs or countersunk washers 52 acting at the other end on a support washer 53 resting on the tip of the spring.

At its free end, the angular section 47 of the ejection device 44 has two opposite edges with a piston 38 or 39 (FIGS. 9 and 10).
The embodiment shown has two oblique bearing surfaces 55 which bear against the vanes of the fork 56 which are beveled in a corresponding manner and which are integral with one of the pistons 39).

The device constituted by the pistons 38 and 39 and also by the screw 40 is mounted in a floating manner in the receiving chamber 37 and thus prevents the elastic redundant 46 from exiting the receiving chamber 37 while providing automatic protection for the slider 5. It is possible to achieve a 6-output. By acting on the screw 40, the movement of the pistons 38 and 39 can be carried out in the opposite direction to the clamping and tightening of the tip of the slider 5 or to the loosening of the slider;
and limit the opening of 39.

Before inserting the device into the frame 35 through the taper 1, the screw 40 is inserted into the bottom of the receiving chamber 37 by the piston 38 using a key.
The pistons 38 and 39 are operated in the direction of maximum separation until they press against the ring 46 and the other piston 39 presses against the ring 46. In this position, the ejection device 44 is moved until its shaft 50 presses the elastic ring 51 against the support washer 53. 35 and then the screw 40 is inserted into the slider 5 so that the forks 41 and 42 of the piston are inserted into the slider 5.
is actuated in the opposite direction so as to engage and approach the gripping contour 28 of the slider 5, so that this slider 5 is pulled towards the rear side of the lug frame 35, with the flange 4 sticking to the front side of said frame 35.

Simultaneously with this movement, the device 44 is moved back under the action of the blades of the inclined fork 56 which press against its oblique support surface 55.

At the end of the tightening of the screw 40, an effective retention of the taper 1 within the frame 35 is obtained.

Loosening and releasing of the attachment device of the invention is accomplished by reversing the operations described above for tightening, with the screw 40 being actuated in the opposite direction by the two stones 38 and 39.
The retraction of the piston 39 in the direction of the ring 46, which has the effect of disengaging the slider 5 from the fork 41, 42 of the
The free end of presses against the slider 5 and thus allows the taper 1 to move until it is released. If the device is not secured by the action of the spring 52, this release can be obtained by applying a single blow of an I-hammer to the free end of the shaft 50.

12 and 13 show a modified example in which this device is applied to the tool holder for a lathe or turning center according to FIGS. 9 to 11. In this example, the piston 39 of the gripping means 36 ' has no inclined fork, the ejection device 44' is inserted into a cutout 43' defined between the pistons 38' and 39', and the piston 38',
A piston 57 with an elongated hole 58 through which a 39" operating screw 40' passes, and a ball passage 61 that coincides with the axis of the taper 1 and is accommodated in a circular groove 61'. frame 35 translationally coupled to a small diameter portion 60 of
and a cooperating actuating screw 59 of the piston 57. Said screw 59 is provided with a hollow operating polygon 62, and the piston 57 is provided with a transverse pin 63 extending parallel to the axis of the screw 40' in the vicinity of its connecting end to the screw 59, the tips of which It is inserted into the vertical groove 64 of the storage chamber 37 of the frame 35.

The insertion of the mounting device into the frame 35 takes place, the piston 57 is in a retracted position in the direction of the rear face of said frame 35, and the screw 40' is operated in the direction of maximum separation of the pistons 38' and 39'. . After the taper 1 has pressed against the inner wall of the frame 35, the screw 40' is used to pull the slider 5 to press the flange 4 against the front surface of the frame 35, as explained above with respect to FIGS. 9-11. The pistons 38' and 39' are operated in opposite directions to bring them closer together. This also applies to the automatic commensuration of pistons 38' and 39'.

To untighten the device, operate the screw 40' so as to separate the pistons 38'l and 39', and then use the key inserted in the operating polygon 62 to tighten the piston 5.
7 is tightened to bring the piston tip into contact with the slider 5, and the slider is pressed in order to push the taper 1 to the outside of the frame 4. After this operation the screw 59 must be returned to its starting position.

If the reverse operation of the screw 59 is forgotten, when the piston 57 is moved, it is moved outside the groove 64 of the receiving chamber 37 and is constituted by a transverse pin 63 located between the pistons 38' and 39'. Safety is ensured and as a result the screw 40'
When operating these pistons with the help of the pistons, they automatically impinge on the bins 63.

The embodiment according to FIGS. 9 to 13 allows use of the toe holder according to the invention by manual or automatic exchange.

The frame 35 of FIGS. 9 to 13 may be provided for manually securing and tightening the tool holder device, although other tightening operations may also be possible using the device, so automatic If a replacement device is used, the taper and slider mounting devices remain the same. Only the manual tightening and ejection devices are replaced by a corresponding hydraulic system, so that all tool holders of the turning sensor can be replaced automatically in the same way as in milling or machining centers. Similarly, by providing an automatic actuation device for manual tightening and loosening devices on the turret workbench, the device of the present invention can be received at the current position of the tool holder having an inner cylindrical hole in the turret tool holder after the turret is modified. 77 for
It is possible to provide a No. 24 cone within a cone, so that the user can arrange the same tool holder for turning and milling centers.

The invention enables conical and end-face pressing for attachments, tool holders and tools, in particular 7
/24 conical tapered shank type mounting device can be realized without the need to modify the spindle of the current machine and therefore without additional modification costs, and the flange end face to the end face of the machine spindle. The pressing is done without requiring strict tolerances in length.

Furthermore, the device according to the invention can be used interchangeably on all machines and can even be equipped with a machine magazine mixed with standard tools. Similarly, it is possible to use current tool changers and tighten the machine spindle with a slider in the same way as using the device.

Of course, the present invention may be modified with respect to specific substitutions or configurations of various members as described above and shown in the accompanying drawings.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of the device of the present invention, FIG. 2 is a partial sectional view showing the slider in a position to clamp the device, and FIG.
7 are side views, partially in section, of some possible embodiments of the front portion centered in the taper, and FIG. 8 is a side view similar to FIG. 1 of a variant embodiment of the invention. Fig. 9 is a side sectional view showing a device applied to a tool holder for a lathe;
Figure 10 is a partial sectional view taken along line A-A in Figure 9;
The figures are a sectional view taken along the line B-B in Fig. 9, Fig. 12 is a sectional view similar to Fig. 9 of a modification that allows the device to be attached to a tool holder for a lathe, and Fig. 13 is a sectional view taken along the line B-B in Fig. 9. A in the diagram
- It is a partial sectional view taken along the A line. 1...Taper, 2...Spindle, 3
...Front, 4...Flange, 5...
...Slider, 6...Elastic device, 7...
...Adjustment means, 8-11...holes.

Claims (15)

[Claims] (1) A mounting device that is applied to the taper and end face of an attachment, tool holder, and tool tool, and has a tapered shank, especially a 7/24 cone, and is mainly used for inserting a taper into the main shaft and for centering within the taper. A front part with a flange pressed against the main shaft surface, a taper and front assembly slider, and a pressure-mounted slider between the taper and the front part that presses the taper in the main shaft into the locking position. An apparatus characterized in that it is constituted by an elastic device having a pressure applied thereto and adjustment means for said pressure device. (2) The taper has a length reduced by a few tenths of a millimeter on each side compared to the current taper, and has two centered concentric holes at the front of the hole, and the hole has a diameter smaller than that of the concentric hole. small and applied to the receiving chamber of an elastic device, which on the side opposite the concentric hole presses against the adjusting means housed in the bottom of said hole, said hole leading to the opposite side of the taper and guiding the slider. At this level, the slider is provided with an annular packing and presses against the rear face of the taper with a bearing surface, and the face of the taper facing towards the front flange accommodates the annular packing. 2. A device according to claim 1, comprising a circular groove in the chamber. (3) The front part with a flange that presses against the spindle end face is centered within the taper using two concentric cylindrical parts each inserted into a corresponding hole in the taper, and further using a slider. The flange is clamped into said taper against the action of an elastic device, and further characterized in that the flange has a V-shaped circumferential groove in its center for receiving an arm of a tool changer. The device according to any one of clauses 1 and 2. (4) The front cylindrical part further carries a key or cylindrical pin rotatably interlocked between the taper and the front part inserted into the corresponding groove of the bore of the taper on the one hand, and a front cap screw on the other hand. 4. Device according to claim 1, characterized in that it comprises two receiving grooves. (5) the elastic device housed in the hole is more advantageously a stack of countersunk washers, a coil spring, a plurality of springs extending in parallel in an annular chamber defined by the hole and the slider;
or by means of hydraulic or pneumatic means or by any other elastic device, the compressive force of said elastic device cooperating with a thread in the bottom of the hole, more advantageously in the form of a threaded sleeve. 3. Device according to claim 1, characterized in that the sleeve is fixed in the position of use by means of a compression screw. (6) The front portion further comprises two concentric holes, one of which is threaded and adapted to receive the threaded tip of the slider, and the other hole is smooth and adapted to receive the threaded tip of the slider. said slider is fixed in the use position of the device via a radial screw inserted forward into the level of one of the grooves receiving the drive tenon of the main shaft, cooperating with an annular packing housed in a circular groove in the main shaft; Device according to any one of claims 1 to 4, characterized in that: (7) Claims 1 to 1, characterized in that the slider is provided at its rear with a grooved cylindrical portion for fixation by the threaded slider instead of the gripping contour. The apparatus according to any one of clauses 3, 5 and 6. (8) The front cylindrical part is provided with a circular groove cooperating with the front cap screw in the taper, as claimed in any one of claims 1 to 3. The device described in. (9) Device according to any one of claims 2 and 3, characterized in that the tapered hole further comprises a cylindrical groove for accommodating an auxiliary annular packing. (10) The device is mounted in a fixed frame by leaning the flange with its taper in front of said frame, said frame being at the level of the slider, perpendicular to or at an acute angle to the axis of the front and taper; Claims 1 to 3 are characterized in that the slider is provided with gripping and tightening means for the tip of the slider, which extends from the elastic ring and is installed in a blind accommodation chamber provided in the vicinity of the open end of the elastic ring. Apparatus according to any one of clause 9. (11) The gripping and tightening means at the tip slides within the storage chamber and can be moved toward or away from using an elastic ring that limits the amount of movement using a screw with a reverse thread groove. It consists of two mounted pistons, on the one hand each having a fork on the side facing the taper for engaging in the gripping contour of the slider, and on the other hand with the slider. The opposite side forms a notch for receiving the ejector of the tapered shank fitting, which ejector extends around the screw at one end and into the taper of the rear face of the frame and the axis of the front part at the other end. 11. Device according to claim 10, characterized in that it extends into the reaching hole. (12) The movement of the piston towards or away from the housing chamber is realized using a simple screw that cooperates with the thread groove on one side of the piston and presses with its head into the pocket of the other piston, and 12. Device according to claim 11, characterized in that an elastic ring forms a stop for the free end of the head. (13) The ejection device is provided with an elongated transverse hole in the receiving chamber of the screw at its tip surrounding the screw and has a rectangular cross section that connects to a cylindrical guide in the hole of the frame, and this cylindrical portion is extended on the one hand by a cylindrical section shaft leading into the hole and equipped at this level with an elastic ring, and on the other hand with a spring or a series of countersunk washers acting at the other end on a support washer supported at the tip of the hole with the help of an elastic ring. 12. Device according to claim 11, characterized in that it comprises: (14) The rectangular cross-section of the ejector has on two opposite edges two diagonal bearing surfaces integral with one of the pistons and resting against correspondingly beveled fork vanes. 14. Device according to claim 13, characterized in that: (15) The piston of the gripping means does not have an inclined fork, and the ejection device is inserted into a limited notch between the pistons,
and a piston with an elongated hole for passing an operating screw of the piston, and translationally coupled to the small diameter portion of the piston through the passage of a ball coinciding with the axis of the taper and housed in a circular groove. It is constituted by a screw of the frame and a cooperating actuating screw of a piston, said screw having a hollow operating polygon, the piston having a transverse section extending parallel to the axis of the screw in the vicinity of its connecting end to the screw. 12. Device according to claim 10, characterized in that it comprises pins, the tips of which are inserted into the longitudinal grooves of the receiving chambers of the frame.