DE2658929A1 - Pressure medium-operated chuck - has working chamber containing axially movable piston with integral clamping sleeve - Google Patents

Abstract

The pressure medium-operated chuck has a main body incorporating a working chamber in which a disc-shaped piston moves axially. A cylindrical clamping sleeve is movable axially on the inner cylinder face of the chamber and in the path of movement of the working piston. A pressure medium transfer system comprises four ring-shaped parts and moves the medium from a stationary feed part to the rotating main body. The transfer point between the main body and the clampin sleeve is sealed by sliding seals.

Description

Hydraulic operated collet chuck

Power operated collet chucks are used for multi-purpose lathes and Converting multi-purpose lathes, for example, for processing bar material. These Collet chucks are used as so-called front-end chucks with the connected to the front end of the machine spindle, where the three-jaw chuck otherwise sits.

Compared to the normal collet chuck device with a draw tube that from the rear end of the machine spindle through this onto the collet is screwed on and always operated at the end remote from the collet must be, the front end chucks have the advantage that the passage width of the Machine spindle that pressing can be fully exploited the chuck can be done from the front, i.e. from the processing point, and that the clamping and releasing are generally carried out faster and safer can.

Mechanically through muscle power by means of a toggle lever arrangement operated collet chucks have a very simple structure and accordingly low manufacturing costs. However, their resilience is despite the toggle lever transmission limited.

Because of the necessary translation, their clamping path is only very small. They are therefore only suitable for tightly tolerated, e.g. drawn or peeled bar material or otherwise pre-machined workpieces with a small diameter. Also require they require a not inconsiderable amount of effort by the operator with each clamping process.

In the case of the collet chucks operated by pressure medium, the operating effort reduced to the actuation of switching elements. You can change the workpiece run faster and, above all, safer and they have a much higher rate Resilience. The well-known fluid-operated collet chucks can be divided into two Divide groups. The first group includes those collet chucks that or have an energy storage device in their revolving base body, which is usually through several sets of disc springs is formed and in the idle state of the chuck the Keeps the collet taut. The collet is operated by means of a pressure medium Piston drive released, which in a stationary working space through the Has pressure medium axially displaceable working piston, the actuating force of which is transmitted via roller bearings to the rotating parts of the chuck and there overcoming the clamping force of the spring force accumulator that clamps the collet Clamping parts moved apart in the axial direction, thereby releasing the collet. The second group includes those collet chucks where in or on their revolving base body a spring force storage device for tensioning the Collets does not exist. With these chucks, the clamping force is used to clamp the Collets from the outside, from a stationary working piston via roller bearings transferred to the rotating clamping parts. With this piston drive, which, as with the first group of pressure medium-operated chucks, a work area and a has therein axially displaceable working piston by the pressure medium, is accordingly During the clamping operation, the pressure medium is constantly supplied and for releasing the collet the pressure medium supply interrupted.

Usually there is still a return spring for the tensioning parts, which Ensure that the clamping parts are released safely after the clamping force has been interrupted target.

In the case of the collet chucks of the first group operated by pressure medium (e.g. according to DAS 16 02 716) are the piston drive for loosening the collet and the its release force on the rotating clamping parts transferring rolling bearings only during the period of time during which the collet is released for the workpiece change is. With these collet chucks, however, it is very difficult to find the individual disc spring sets adjust the spring force accumulator to a spring force that is the same as one another, in order to avoid warping or tilting of the parts clamped against one another. Strictly speaking, this is only for a very specific setting state with the help of a Setting gauge possible. Since the clamping force of the spring force accumulator is path-dependent, the set clamping force is only used for a very specific workpiece diameter achieved. The clamping force is smaller for workpieces that are too small and for workpieces with excess it is greater than the target value. In the former case, the safe Clamping of the workpiece may be at risk.

In the latter case, the workpiece can be overstressed, if it is made of a material of low strength or if it is a thin-walled hollow part is. With these collet chucks, the setpoint can be the clamping force either not at all or only with great effort and under great Difficulties and at most in very rough stages change and adapt to different clamping force requirements of the workpieces. The possible uses these collet chucks are therefore very limited.

With the collet chucks of the second group, the clamping force change within wide limits and to different clamping force requirements of the Adjust workpieces in that the pressure of the pressure medium for the actuation of the Piston drive is changed. However, these collet chucks have the major disadvantage that the roller bearings that the clamping force of the stationary piston drive on the rotating clamping parts are always fully loaded during the clamping operation are. This increases the transferable clamping force as well as the operating speed limited to a certain maximum value.

As a result, these collet chucks can also be used limited.

The invention mentioned in claim 1 is based on the object to create a collet chuck actuated by pressure medium, its possible uses go further than with the known collet chucks.

Due to the arrangement of the working space on the base body of the collet chuck and by the transfer of the pressure medium from a stationary feed part the pressure medium transmission element to the revolving base body can be in the working space working piston axially displaceable directly by the pressure medium, in particular act on the sliding clamping part without the interposition of roller bearings and thus clamp the collet in the most direct way possible. By changing the Pressure medium pressure, the clamping force can be changed at will and all clamping force requirements be adjusted. Due to the lack of roller bearings loaded by the clamping force This collet chuck can be used at all machine speeds will.

Advantageous further developments of the invention are set out in the subclaims described.

In a collet chuck configured according to claim 2, the cylindrical guide and sliding surface between the base body and the one that can be moved within it Clamping part acted upon by the pressure alone medium. / because of that, even more but in a collet chuck configured according to claim 3 and 4, in particular Pressure lubrication is created for the movable clamping part during the clamping process. As a result of the floating mounting "of the sliding clamping part, the frictional forces vanishingly small and the thrust generated by the working piston can be fully integrated into Tension can be implemented. At the same time, as a result of the special effect of this Pressure lubrication the fit between the cylindrical guide surface of the base body and the sliding clamping part are kept very tight, creating an extraordinary high clamping accuracy is achieved. As a result of the whole guide surface of the sliding The pressure lubrication that encompasses the clamping part becomes less of the one sliding along one another Avoided cylindrical surfaces5, which at least to this extent reduce the service life of the collet chuck is extended considerably and the clamping accuracy during the entire service life remains unchanged.

Through the pressure medium line within the wall of the displaceable On the clamping part, separate lines and the structure of the collet chuck are saved simplified. In a collet chuck designed according to claim 7, the mutually displaceable parts, namely the working piston and the clamping sleeve, a high level of concentricity among each other, which means that their cylindrical guide and sliding surfaces are precisely aligned with one another. The design of the collet chuck according to claim 8 simplifies the processing of its base body. When designing the collet chuck according to claim 9 are separate parts for the formation of the Working space saved and thereby the manufacturing costs for the collet chuck Decreased in the design of the collet chuck according to claim 10 is the machining of the cylindrical sliding and sealing surface of the working space much easier. As a result, a higher concentricity and Form accuracy and a better surface quality can be achieved. The design the collet chuck according to claim 11 simplifies the assembly of the collet feed quite considerably. When designing the collet chuck as required 12 is an increased security against unintentional release of the locking ring of the workspace cover and thus this reached itself.

By designing the collet chuck according to hrispructì 13 uIrd protects the pressure medium transmission element from external influences that affect his Could affect the way it works. ei design of the collet chuck according to Claim 14 ensures that the small amount of leakage of the pressure medium can be fed back to the pressure medium circulation.

Bni following the invention is based on one in the Ze ichnunq im Longitudinal section illustrated embodiment explained in more detail.

The collet chuck essentially has a rotation body trained base body 1 with an axially continuous passage opening 2 for the implementation and recording of the workpieces. The one on the left in the drawing The end of the base body 1 is designed as a flange part 3. There are too many groups of alternating fastening holes in the circumferential direction, and once in the form of threaded sack 4 and once in the form of through holes 5. By means of the flange part 3 and one or the other group of fastening holes and suitable screws can be attached to the collet adder with the front end of the Machine spindle of a machine tool are connected.

A hollow cylindrical Fühzangteil closes on the flange part 3 6 at deE an inner cylinder surface 7 and an outer Z-cylinder surface 8th has that are aligned with each other. On the inner cylinder surface 7 is a cylindrical Clamping sleeve 9 guided axially displaceably. This has an inner cone 11 for tensioning the collet 12, which in turn is provided with an outer cone 13. the Clamping sleeve 9 serves as the displaceable clamping part for clamping the collet 12. At the end of the guide part 6 facing away from the flange part 3 there is a clamping ring 14 firmly connected to the guide part 6. The clamping ring 14 has an external thread provided, with which he in a corresponding internal thread at the front end of the guide part 6 is screwed in. The clamping ring 14 forms an end abutment for the Collets and thus represents the fixed clamping part for them.

Within the flange part 3, the base body 1 has a cylindrical shape Recess 15, as an extension of the passage opening 2 on the inner cylinder surface of the guide part 6 connects and is aligned with this. This recess 15 at the periphery delimiting wall 16 of the base body 1 runs after that of the machine spindle facing side freely. At a certain axial distance from the flat transition surface between the inner cylinder surface 7 and the recess 15 is a circular ring-shaped Lid 17 inserted. In the to the machine spindle. indicative axial direction is he is supported by means of a locking ring 18 relative to the base body 1 and held. On its circumferential surface it has a circumferential groove into which one acting as a sliding seal sealing sleeve 19 is used.

The wall 16 of the recess 15, whose flat transition surface to the inner The cylindrical surface 7 of the guide part 6 and the cover 17 border in the base body 1 on three sides a working space 21 in which a disc-shaped working piston 22 is arranged axially displaceably with a circular piston surface. The working piston 22 has one in the direction of the machine spindle up to the outside of the cover 17 extending approach 23, on its cylindrical outside the inner circumferential surface of the cover 17 rests slidably and by means of a sliding seal acting sealing collar 24 is sealed.

The working piston 22 is formed in one piece with the clamping sleeve 9, so that their cylinder surfaces are particularly precisely aligned with one another and also the from the working chamber 21 acting on the working piston 22 axial pressure forces can be transferred directly to the adapter sleeve.

The inner cylindrical surface 7 of the guide part 6 is used for the clamping sleeve 9 as a guide surface. Close to the ends of the common cylindrical contact surface of the guide part 6 and the clamping sleeve 9 has the guide part 6 in its inner Cylinder surface 7 has a circumferential groove 25 in each of which an O-ring 26 is inserted is. These O-rings 26 act in the axial direction as sealing elements for the common contact surface of the guide part 6 and the clamping sleeve 9.

Approximately in the middle of the axial extent of the guide part 6 is a radial through opening 27 is present in the wall thereof. In the radial plane of this The inner cylindrical surface 7 of the guide part 6 has a through opening 27 flat circumferential groove 28. The outer circumferential surface has roughly the same radial plane the clamping sleeve 9 also has a circumferential groove 29, so that the two circumferential grooves 28 and 29 at least partially overlap in the axial direction.

A radial bore 31 extends from the circumferential groove 29 of the clamping sleeve 9 which extends inwardly into the wall of the clamping sleeve 9. To it is followed by an axial bore 32, which extends in the direction of the working piston 22 extends back and through this so that it is on the working space 21 facing end face of the piston 22 opens into the working chamber 21.

In the radial plane of the radial through opening 27 in the guide part 6 is on the outer cylinder surface 8 of a pressure medium transmission member 33 arranged. This has four annular parts 34, 35, 36 and 37, the whole certain valve cuts. The two inner ring-shaped grooves 34 and 35 are screwed together in the axial direction. The same are also on the outside located annular part 36 and the voti ring surrounding the remaining three parts fö rin ige part 37 screwed together. The two inner rinq-shaped Parts 34 and 35 each have an aligned inner cylinder surface with which they on the outer cylindrical surface of the guide part 6 on the base body 1 with a sliding fit issue. The inner cylindrical surfaces of the annular parts 54 and 35 each have a circumferential groove in which an O-ring is inserted as a sealing element. In the axial area located between these two diaphragm elements has the annular Part 34 has a circumferential groove 38. It is roughly the same radial plane as that radial through opening 27 located in the guide part 6. In the circumferential groove 38 of the annular part 34 open out several circumferentially distributed conduction paths of the Druckmi ttelüber tragungsorganans, which is on the cylindrical outside of the outer ring-shaped part 36 start from a circumferential groove 39. In the axial direction on both sides This circumferential groove 39- two further circumferential grooves are available in the O-rings are inserted as sealing elements. On the outer circumferential surface of the annular Part 36 is an inner cylindrical surface 41 of a stationary relative to the base body 1 Feed part 42 with a sliding fit. In the same radial plane in which the circumferential groove 39, the feed part 42 also has its inner cylindrical surface 41 a circumferential groove 43. The feed part 42 has one located at the top in the drawing Connection piece 44 for a pressure medium supply line and a connection piece located below 45 for a pressure medium discharge.

The feed part 42 has an approximately U-shaped cross section, whose U-profile is open towards the guide part 6 of the base body 1. On the that Guide part 6 facing the end of the both end-face flange parts is the feed part 42 by means of a ball bearing 46 and 47 on the outer cylinder surface 8 of the guide part 6 mounted. A sealing cuff 48 and 49 each seal this Feed part 42 relative to the base body l.

In the flat transition area between the wall 16 of the recess 15 and the inner cylindrical surface 7 of the guide element 6 are several in the base body l axial recesses 51 are present, in the individual helical compression springs 52 as return springs for the working piston 22 are used. In this flat tibe there is a passage area there is also at least one further axial recess 53 into which there is play an axially aligned pin 54 engages that plagues working piston 22 is arranged, this bolt the recess 53 act as a rotation lock for the working piston 22 and the clamping sleeve 9 together.

For use on a machine tool such as a teaching lathe, the base body is made by means of its facing part 3 at the front end of the machine spindle attached. The clamping ring 14 is loosened, a collet 12 with the desired The clamping diameter is pushed axially into the clamping sleeve 9 and the clamping ring 14 reattached. The working piston is in the idle state of the collet chuck 22 moved by the return springs 52 in the drawing to the left, so that the Inner cone 11 of the clamping sleeve 9 and the outer cone 13 of the collet 12, if necessary Loosely attach ane inarider to 1 so that the S'iriri pliers 12 are not clamped. After this A work piece is guided either from the front, i.e. from the right in the drawing or through the hollow machine spindle from the back to the collet 12 into it, a pressure medium is fed under pressure via the connecting piece 44. The pressure medium is from the always stationary supply part 42 by means of also known as a "hydraulic slip ring" (Konstruktien, Issue 7/74) 33 to temporarily passed stationary or permanent circumferential base body 11. From the transition point between the pressure medium transmission element 33 and the guide part 6 of the base body 1, the pressure medium passes through the radial through opening up to the circumferential groove 28 of the inner cylinder surface 7 of the Guide part 6.

From there it passes into the circumferential groove 29 of the clamping sleeve 9.

The pressure medium also penetrates along the common contact surface between the guide part 6 and the clamping sleeve 9 up to the sealing this surface O-rings 26 in front and thereby ensures a floating mounting of the clamping sleeve 9 in the guide part 6 of the base body 1. The pressure medium arrives from the circumferential groove 29 Via the radial bore 31 and the subsequent axial bore 32 into the working space 21 inside. There the pressure medium exerts an axial thrust force due to its pressure force on the piston 22, due to which the piston 22 pushes the clamping sleeve 9 against the clamping ring 14 shifts towards. The collet chuck 12 with its outer cone 13 is thereby Section between the two formed by the clamping sleeve 9 and the clamping ring 14 Clamping parts clamped, whereby it closes around the workpiece and this for the processing holds. The clamping force with which the workpiece is held, can be adjusted at will by changing the hydrostatic pressure of the pressure medium will.

To release the collet chuck 12, the pressure of the pressure medium is increased reduced to a low value of about 2 to 3 bar.

As a result, the acting as return springs on the working piston 22 are able Helical compression springs 52 push back the working piston 22 and thereby the clamping sleeve 9 with its inner cone 11 to be withdrawn from the collet 12 with the outer cone 13. As a result, the jaws of the collet 12 spring apart, so that the workpiece is released again.

L e r s e i t e

Claims (14)

Claims 1. Pressure medium operated collet chuck, with ainem with the machine spindle rotatably connectable base body, the at least one inner Has cylindrical surface, with two clamping parts once in the form of a clamping sleeve that has an inner cone for clamping the collets, and once in the form of a arranged on the free end of the grurid body facing away from the machine spindle frontal abutment for the collets, one of these clamping parts is guided axially displaceably on the inner cylindrical surface of the base body, with a cylindrical working space for the pressure medium with a circular cross-sectional area, with a working piston that can be axially displaced in the working space and that with the displaceable Clamping part is coupled to the transmission of the axial clamping forces, and with at least one return spring acting on the sliding clamping part, characterized in that that the working space (21) is arranged on the base body (1) that the displaceable Clamping part (9) itself or a part connected to it, at least in the direction of movement for clamping the collets (12) arranged in the path of movement of the working piston (22) is and that a pressure medium transmission member (33) is present, by means of which the pressure medium from a stationary supply part (42) to the rotating base body (1) is transferable, from which the pressure medium is fed to the working space. 2. Collet chuck according to claim 1, characterized in that the pressure medium line from the transition point (28, 29) between the pressure medium transfer element (33) and the basic body (1) to the inner cylindrical surface (7) of the Base body (1), from this to the clamping part (9) guided in it to be displaceable and along this, preferably within its wall, to the working space (21) leads there. 3. Collet chuck according to claim 2, characterized in that the transition point (28, 29) of the pressure medium between the base body (1) and the movable clamping part (9) in both axial directions by sealing elements, preferably in the form of sliding seals (26), is sealed. 4. Collet chuck according to claim 3, characterized in that the sealing elements (26) from the transition point (28, 29) of the pressure medium in the axial direction Direction away, preferably close to the ends of the common cylindrical Contact surfaces (7) between the base body (1) and the movable clamping part (9) are arranged. 5. Collet chuck according to claim 3 or 4, characterized in that that the sealing elements in the form of O-rings (26) or sealing sleeves in paragraphs or in circumferential grooves (25) delimiting the inner cylinder surface (7) Wall (6) of the base body (1) are arranged. 6. Collet chuck according to one of claims 1 to 5, characterized in that that at the transition point (28, 29) of the pressure medium between the pressure transmission element (33) and the base body (1) and / or between the base body (1) and the displaceable Clamping part (9) at least one on each of the parts forming the transition point There is a circumferential groove (28 or 29). 7. Collet chuck according to one of claims 1 to 6, characterized in that that the displaceable clamping part, preferably the clamping sleeve (9), and the working piston (22) are integrally formed. 8 collet chuck according to one of claims 1 to 7, d a d u r c h e k e n n n z e i n e t that the inner cylindrical surface (7) of the base body (1) runs out freely on the side facing away from the machine spindle and that the front abutment for the collets by one with the base body (1) connected, preferably screwed, clamping ring (14) is formed 9 collet chucks according to one of claims 1 to 8, characterized in that the working space (21) by a cylindrical recess aligned with the inner cylindrical surface (7) (15) of the base body (1) is formed on the inside by a cylindrical Extension (23) of the working piston (22) is completed. 10. Collet chuck according to claim 9, characterized in that the wall (16) of the base body (1) delimiting the working space (21) on the circumference the side facing the machine spindle runs out freely and that of the work area to this side axially delimiting wall part through a into the outer cylindrical surface of the working space inserted cover (17) is formed, on the one hand opposite the outer cylindrical surface of the working space and on the other hand opposite a hollow cylindrical Extension (23) of the working piston (22), preferably by means of sliding seals (19; 24) is sealed. 11. Collet chuck according to claim 10, characterized in that the cover (17) of the working space (22) by means of a locking ring (18) opposite the base body (1) is supported. 12. Collet chuck according to claim 11, characterized in that the cover (17) is a matched to the dimensions of the locking ring (18) has frontal heel. 13. Collet chuck according to one of claims 1 to 12, characterized in that that the stationary feed part (42) at least partially radial bearings, preferably also by means of axial bearings, preferably by means of roller bearings that act radially and axially (46; 47), is guided on the base body. 14. Collet chuck according to one of claims 1 to 13, characterized in that that the stationary supply part (42) on both sides of the pressure medium transmission element (33) and the transition point (38) of the pressure medium between the pressure medium transfer element (33) and the base body (1), preferably by means of sliding seals, opposite the Base body (1) is sealed.