TOOL HOLDER, ROTATION TOOL, AND COMBINATION OF TOOL HOLDER AND TOOL

Abstract

A tool holder has a base element, a deformable receiver for clamping a tool and at least one locking element configured for preventing an axial extraction of the tool from the tool holder through engaging a corresponding opposite element at the tool. The at least one locking element is integrally configured in one piece with the receiver.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of patent application Ser. No. 13/728,094, filed Dec. 27, 2012, which was a continuation-in-part of application Ser. No. 12/296,892, filed Oct. 10, 2008, now U.S. Pat. No. 8,505,893 B2, which was a § 371 national stage filing of international application No. PCT/EP2007/003118, filed Apr. 5, 2007, which designated the United States; this application also claims the priority, under 35 U.S.C. § 119, of German patent applications 20 2011 109 498.0, filed Dec. 27, 2011, and 10 2012 110 392.5, filed Oct. 30, 2012; the prior applications are herewith incorporated by reference in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to tool holders comprising a tool holding fixture, in particular shrink fit chucks and other chucks for receiving rotation tools, as well as to rotation tools for such tool holders.

Tool holders with clamping chucks, in particular shrink fit chucks, are well known. They are being used for clamping tubular tools, turning tools, milling tools, reaming tools, and grinding tools, and similar through a thermally induced shrink process. Typically, such shrink fit chucks are thermally heated by an inductive shrink system, whereby the inner diameter of the shrink fit chuck is expanded. When the inner diameter is enlarged, a tool to be clamped is inserted into the shrink fit chuck, wherein the ratio of the inner diameter of the shrink fit chuck to the shaft diameter of the tool is configured, so that the tool is clamped torque proof in the shrink fit chuck after subsequent cooling of the shrink fit chuck.

From WO 01/89758 A1 it is known to inductively heat the sleeve section by means of an annular coil assembly, substantially surrounding the sleeve section in a coaxial manner. The coil assembly is connected to a high frequency AC generator and induces Eddy currents in the metal sleeve section, which heat the sleeve section. In order to avoid scatter flux and to concentrate the magnetic flux, magnetic flux concentration elements made of soft magnetic electrically substantially nonconductive material, like e.g. ferrite or similar, are disposed at the faces and at the outer circumference of the coil assembly, which direct the magnetic flux generated by the coil assembly to the sleeve section of the tool holder, and in particular into the portion of the free end of the sleeve section.

The problem with tool holders comprising clamping chucks for rotating tools which comprise cylindrical receiving shafts is the axial migration of the rotation tool along the rotation axis of the clamping chuck out of the clamping chuck during operation. Said axial migration of the rotating tool is caused by vibrations, which occur while machining the work piece with the rotating tool. Due to this detrimental effect, the work pieces cannot be machined precisely and according to their dimensional specifications. Furthermore, canting the rotating tool in the work piece or even in the clamping chuck receiving the work piece can lead to dangerous accidents. Under non-favorable conditions, the rotating tool can even leave the clamping chuck of the tool holder during operation in a marginal situation, and thus create a great hazard for the machine operator.

SUMMARY OF THE INVENTION

It is thus the object of the present invention to provide a tool holder with a clamping chuck, in particular a shrink fit chuck or similar, in which an axial migration of the rotating tool, like a spiral drill, profile drill, screw drill including tap, end facing drill, cutter, etc., is not possible during operation, but in which the rotating tool is mounted torque proof, as well as also axially fixated with respect to the rotation axis without any migration out of the chuck.

This object is accomplished according to the invention as claimed, wherein advantageous improvements of the invention are provided by the features of the dependent claims.

According to the invention, a tool holder according to the invention comprises a pullout preventer for the tool, which prevents axial migration of the tool out of the tool holding fixture. Thus, the pullout preventer comprises at least one locking element and at least one locking groove corresponding thereto, receiving the locking element, which interact through form locking. Thus, the locking element and the locking groove are at least partially configured with a ball head profile, wherein either the clamping chuck comprises the locking elements and the tool comprises the locking grooves, or vice versa.

Furthermore, thus the locking grooves, which are disposed starting at the face side, either on the tool shaft, or in the tool holder, can be provided expanded with reference to the groove width, in order to thus facilitate easier insertion of the tool into the tool holder.

In a particularly preferred embodiment, the tool holder comprises at least two rotatably supported balls on the tool holder side, wherein on the side of the rotation tool at least two locking grooves at the shaft of the rotation tool, which correspond to the balls, interact in a form locking manner. The two locking grooves are thus preferably provided like a thread at the cylindrical tool shaft starting at the face side of the cylinder shaft along the circumferential surface of the cylinder shaft. Said locking grooves disposed on the circumferential surface of the cylinder shaft of the rotation tool are provided with a left pitch direction for tools with a left groove and are provided with a right pitch direction for rotation tools with a right groove. Thus, the locking grooves can also be configured in axial direction and thus parallel to the rotation axis, wherein this still provides safety against rotation for the tool.

In order to clamp the rotation tool according to the invention, like e.g. spiral drills, profile drills, screw drills including taps, end facing drills, cutters, and arbors for other tools etc. in the clamping chuck according to the invention, e.g. the shrink fit chuck of the tool holder, the induction coil is initially turned on in the shrink fit chuck, this means the induction coil is connected to high frequency AC power. Due to the Eddy currents occurring in the sleeve section of the tool holder generated by induction from the coil surrounding the tool holder, the sleeve section is quickly heated up, so that it expands thermally, and thus the inner diameter of the receiver opening is enlarged. Now, the rotating tool can be inserted into the receiver opening with its shaft. The face of the rotating tool thus reaches the balls protruding into the inner cavity of the receiver opening and stops there. Depending on the pitch direction of the locking grooves of the rotating tool, said tool is now rotated counterclockwise or clockwise with respect to the rotation axis, so that the balls can engage the ball receiving grooves. Further rotation forces a helical rotation, and thus an axial pull-in movement of the rotation tool into the shrink fit chuck or similar, until the face of the cylindrical shaft contacts the shrink fit chuck or until the balls have reached their final position in the ball receiving locking grooves. The induction coil can be turned off now. Due to the quick cooling which occurs now, the shrink fit chuck shrinks back again to its original size, which connects the cylindrical shaft torque proof with its circumferential surface to the inner circumferential surface of the receiver opening of the shrink fit chuck with a press fit. Since the rotation direction of the locking grooves corresponds to the rotation direction of the rotating tools during the operation of the tool also under high load, that means, under high cutting resistance of the work piece and under large feeds of the tool or of the tool table, an axial migration of the rotation tool along the rotation axis out of the chuck cannot occur anymore. Through the interaction of the balls in the tool holder with the ball profile locking grooves in the tool shaft, and the thread configuration of said locking grooves, an axial locking is accomplished. Said axial locking can only be released by rotating the rotating tool against the operating direction of the rotating tool and pulling it out of the clamping chuck. A rotation performed against the operating direction of the rotation tool during operation is thus, however, not possible when machining the work piece with the rotating tool. Furthermore, said rotating movement, due to the torque proof press fit, is not possible during operation either. Thus, the rotating tool cannot move out of the shrink fit chuck or similar.

Thus, the machining remains precise, and the dimensions can be kept within the required tolerances. Since axial migration out of the chuck is prevented by the present invention, production can be run efficiently and more economically, since, compared to prior art tool holders with clamping chucks, very little scrap is produced. Additionally, thus another cause for accidents and thus accident risk for the machine operator is excluded.

Instead of the rotatable balls held in a press support in the clamping chuck, also cylindrical pins with a partial or half sphere can be used at one of the faces. These are disposed in the support bore hole instead of the balls, wherein these pins either require a protruding shoulder, so that the cylindrical pin does not fall into the inner cavity of the receiver opening, or an outer thread which corresponds to the inner thread of the support bore hole. Using balls has the advantage compared to using cylindrical pins with a partially spherical or semi-spherical head that inserting the rotation tool is easier compared to cylindrical pins, since the balls are rotatably supported and cannot cant relative to the cylindrical shaft. Balls can also be held in the respective support bore hole using a threaded pin. Thus, the threaded pin comprises a configuration receiving the ball even at its face, e.g. shaped as a polygonal recess or as a ball shaped depression or similar. Instead of the threaded pin, also mating pins, bolts or similar can be used.

The pullout preventer according to the invention for tools, in particular for rotation tools in tool holders, with a tool holding fixture is suited in particular for clamping chucks, like e.g. draw-in collet chucks, high precision chucks, hydraulic expanding chucks, and shrink fit chucks.

Advantageously, depending on requirements, the locking grooves in the circumferential surfaces of the shaft of the tool are configured differently. Thus, the locking grooves can comprise a different locking groove path beginning on the face side. It can be helical, L-shaped, curved, or formed from composite paths on an enveloping surface of a cylinder, which is straight in portions and/or curved. In particular, in a helical locking groove path, the direction of rotation has to correspond to the direction of rotation of the grooved tool. This means, for a left grooved tool, the helical locking groove has to have a left pitch direction; for a right grooved tool, on the other hand, the locking groove has to have a right pitch direction. Therefore, there is a locking effect of the pullout preventer.

In another embodiment, the shaft of the tool comprises an outer thread at the end, and the tool holding fixture of the tool holder comprises an inner thread corresponding thereto. In this case, the pullout preventing feature is implemented using the outer thread at the tool, which has a left pitch direction for a left grooved tool, and a right pitch direction for a right grooved tool. In this embodiment, locking elements and locking grooves become obsolete.

In a particularly preferred embodiment, the support bore holes, which receive the locking elements, are configured preferably from the outer circumferential surface of the tool holder until into the inner cavity of the tool holder receiving the tool. Thus, said support bore holes can be configured perpendicular to the rotation axis of the tool holder and so that they intersect the rotation axis, and/or tangentially adjacent to the inner circumferential surface of the cavity which receives the tool. Preferably, the longitudinal axes of the support bore holes are configured at the same angle, and in particular in a plane perpendicular to the rotation axis of the tool.

In another particularly preferred embodiment, in particular for tool holders with shrink fit chuck, balls are supported as locking elements in a ball retainer. Thus, the support bore holes for the respective balls in the ball retainer comprise a smaller. bore hole diameter with respect to the inner circumferential surface than the diameter of the support bore hole. Thus, the balls cannot fall to the inside into the interior of the tool holder, but they only reach over the inner portion of the ball retainer. The ball retainer can thus either be inserted as a separate component in an interlocking manner into the inner cavity of the tool holder, or it can be machined into a sleeve. Thus, the sleeve comprises the respective support bore holes with the smaller support bore hole diameters located towards the inner cavity. The sleeve can thus be pressed or shrunk into the inner cavity of the tool holding fixture, welded to the tool holder, held in a form locking manner by additional threaded pins, and/or fixated with locking elements and locking grooves at the sleeve, as they are described according to the invention at the shaft of rotation tools.

In a particularly preferred embodiment, in particular for shrink fit chucks, the pullout preventer comprises an additional device, which facilitates a support of the tool by the pullout preventer without clearance. Thus, the tool is pressed into the tool holding fixture out of the tool holder by a force imparting element, which is disposed e.g. concentric to the rotation axis of the tool at the bottom of the bore hole of the tool holding fixture. Thus, the pullout preventer contacts the tool without clearance. Since even a small clearance between the pullout preventer and the tool allows the tool a certain mobility, which can also lead to damages of the tool edges. In particular, compression springs in the form of coil springs, conical springs, disk springs, and disk spring packets, and/or elastic or rubber elastic elements can be used as force imparting elements.

In another particularly preferred embodiment of a tool holder with a minimum volume lubrication, said tool holder comprises at least one transfer piece for the minimum volume lubrication, which comprises at least one, preferably plural channels for the pressure buildup or for the pressure compensation. For such a tool holder with such a transfer piece, additional protection may be applied for separately from the pullout preventer. The transfer piece preferably provided as a tube, which can be also comprised of plural components, is preferably formed with a radial flange, and preferably movably received and guided in a bore hole disposed in the tool holder. The tube, which can also comprise different cross section profiles, is preferably supported in the tool holder preloaded by a coil spring, wherein the cylindrical shaft of the tube preferably reaches through the coil spring. Certainly, also other force applying elements, like tension spring, conical spring, disk spring, and/or elastic elements and their combinations are possible. The coil spring is preferably disposed between the radial flange of the tube and e.g. a bottom stop in the tool holder, whereby the tube is supported preloaded relative to the tool holder. The transfer piece is preferably supported in the bore hole, so it is sealed. Thus, the tool holder comprises at least e.g. one shaft seal and/or additional seal elements, like seal rings, seal lips, etc., concentric to the bore hole for the transfer piece or for the tube, wherein said seal elements can also be disposed in the tool holder and/or at the transfer piece or at the tube itself. The channels provided in the form of passthrough bore holes, in particular with circular cross section profile, wherein also other cross section profiles are possible, are preferably disposed in the radial flange of the transfer piece, so that the transfer bore holes in the transfer piece are connected to the transfer bore hole in the radial flange of the transfer piece. Along the cylindrical circumferential surface of the radial flange of the transfer piece, a radial recess is disposed. Therein, an annular membrane is embedded preferably in a form locking manner, which corresponds to the radial cutouts and which is preferably shaped as a section of an enveloping surface of a cylinder. Thus, the circumferential surface recess, in particular provided as a groove, and also the cross section of the membrane embedded in the groove preferably corresponding thereto, can e.g. comprise or a partial ball head profile or other profiles. The annular membrane is preferably formed from an elastic material, in particular from a rubber elastic material, but also other materials are possible, like e.g. carbon fiber material, plastics, Teflon and flexible metals. The channels for the pressure compensation or for pressure venting or pressure buildup are thus in particular connected to the membrane and to the inner cavity of the transfer piece. When pressure is built up in the tool holder, the membrane thus cambers in radial direction, and thus attaches to the circumferential surface of the receiver bore hole of the tool holder. Thus, the transfer piece is locked against axial movement.

The invention relates to a tool holder according to the preamble of claim 22. The invention furthermore relates to a clamping system including the tool holder and a method for producing a tool receiver for the tool holder.

From WO 2007/118626 A1 a tool holder is already known that includes an expansion bushing arranged within a base element wherein the expansion bushing is configured to receive a tool and can be loaded with a pressure fluid for clamping the tool from an outside. The tool holder furthermore includes an extraction preventer including plural locking elements arranged in the base element for engaging corresponding opposite elements at the tool in order to prevent axial extraction of the tool during machining. The locking elements in the known tool holder are configured as locking pins or balls which are moveably supported in respective bore holes of the base element and which engage associated locking grooves at the shaft of a tool to be clamped. In this tool holder, however, the base element has to be machined in a complex manner in order to be able to receive the locking elements.

Thus it is an object of the invention to provide a tool holder as recited supra and a clamping system with a tool holder of this type which can be manufactured more easily and which can be mounted in a simple manner.

This object is achieved through a tool holder with the features as claimed and through a clamping system with the features as claimed and a method for producing a tool receiver for a tool holder of this type with features as claimed. Advantageous embodiments of the invention are defined in the dependent claims.

In the tool holder according to the invention the at least one locking element is integrally configured in one piece with the receiver. Thus, the receiver can be mounted in a simple manner together with the locking elements. Furthermore no space for the receiver is lost through the locking element. The entire available space can be used for the receiver, so that no clamping force is lost.

The clamping system according to the invention includes a tool holder and a tool, wherein the tool holder includes a base element, a deformable receiver for clamping a tool, and at least one locking element integrally configured with the receiver, wherein the locking element engages a corresponding opposite element at the tool for preventing an axial extraction of the tool from the tool holder.

In a particularly advantageous embodiment the receiver is an expansion bushing arranged in a receiving opening of the base element wherein the expansion bushing can be loaded with the pressure fluid from the outside and the at least one locking element is arranged at the inside of the expansion bushing.

The receiver, however, can also be a shrink fit chuck that is integrally configured together with the base element, a reduction bushing that is arranged within a shrink fit chuck or a collet that is arranged within a receiving opening of the base element and deformable through a clamping element, wherein at the at least one locking element is arranged at an inside of the collet.

In an embodiment that is advantageous from a fabrication point of view and from an assembly point of view the at least one locking element can be formed directly at the receiver. In case of an expansion bushing the locking element, however, can also be a separate component that is configured for example as a ball, a locking pin or similar, wherein the component is attached at the expansion bushing.

For directly forming the locking element at the receiver the receiver is advantageously produced according to the invention through a material removing method from a metal solid material by generating a recess, wherein during production of the recess for forming the locking element integrally configured in one piece with the receiver at least one protrusion is left out that protrudes in the recess. Thus, the locking element is integrally formed at the recess. For producing the receiver from a metal solid material, material removing spark erosion methods have proven to be particularly advantageous, which methods are known under the abbreviation EDM (electrical discharge machining) and/or electrochemical removal methods like ECM (electrical chemical machining) or a combination thereof like the method known as ECDM (“electrical chemical discharge machining”). With material removing methods of this type the complex structures for forming protrusions that extend inward in the receiver can be produced, wherein the protrusions form the locking elements according to the invention. Thus, in order to produce the recess in a full material block initially in a first process step chip removing methods can be used and in a final process step material removing electrical discharge machining methods (abbreviated EDM) and/or electrochemical material removing methods can be used through which the fine structures for forming the protrusions are then formed in the recess, wherein the fine structures form the locking elements.

In a particularly advantageous embodiment the at least one locking element is configured at the receiver as an inward extending protrusion for engaging a respective recess at the shaft of a tool to be clamped, wherein this protrusion is advantageously integrally formed with the receiver and generated as recited supra through a material removing electrical discharge machining method and/or through an electrochemical material removal method in a recess from a solid material block. Accordingly, the locking element provided at the receiver can also be configured as a recess and the associated opposite element at the tool can be configured as protrusion. The locking element can have a semicircular or circular cross section for simplified engagement of the associated opposite element.

In an advantageous manner the at least one locking element can extend at least over a partial circumference of the receiver at its inside like a thread turn of a nut. A support that is more even over the circumference can be achieved in that plural locking elements are arranged at the inside of the receiver, which locking elements extends like a thread turn of a nut at least over a partial circumference of the receiver. When there are plural locking elements they are advantageously arranged at the receiver with even angular spacing in circumferential direction.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a sectional view of the tool holder according to the invention, comprising a shrink fit chuck with a separate end mill cutter, which is provided with locking grooves and which is not yet clamped;

FIG. 2 shows a sectional view of the tool holder according to the invention, comprising a shrink fit chuck with an end mill cutter according to the invention clamped therein;

FIG. 3 shows a sectional view of the tool holder according to the invention, comprising a shrink fit chuck with an end mill cutter according to the invention clamped therein;

FIG. 4 shows a sectional view of the tool holder according to the invention, comprising a high precision chuck and an end mill cutter according to the invention clamped therein;

FIG. 5 shows a sectional view of the tool holder according to the invention, comprising a hydraulic expanding chuck with end mill cutter according to the invention clamped therein;

FIG. 6 shows a sectional view of the tool holder according to the invention, comprising an end mill cutter according to the invention clamped therein, where the tool comprises an exterior thread, which is threaded into a corresponding interior thread of the tool holder;

FIG. 7 shows a sectional view of the tool holder according to the invention, comprising balls as locking elements, which are secured by threaded pins;

FIG. 8 shows a sectional view of the tool holder according to the invention, comprising balls as locking elements, which are secured by threaded pins, where the balls are partially recessed into the threaded pins;

FIG. 9 shows a sectional view of the tool holder according to the inven-tion, comprising balls as locking elements which are secured by cylindrical pins in the press fit;

FIG. 10 shows a sectional view of the tool holder according to the inven-tion, comprising a one-piece locking element, which is a threaded pin with a ball shaped embossing at one of its faces;

FIG. 11 shows a sectional view of the tool holder according to the inven-tion, comprising one-piece locking elements, which are cylindrical pins with a ball shaped embossing at one of the faces in a press fit;

FIG. 12 shows a sectional view of the tool holder according to the invention with balls in a separate ball retainer and a sleeve adjacent thereto;

FIG. 13 shows a sectional view of the tool holder according to the invention, comprising balls, which are disposed in a ball retainer, which is machined into the sleeve, wherein the sleeve is pressed in or shrunk in;

FIG. 14 shows a sectional view of the tool holder according to the invention from FIG. 13, wherein the sleeve is welded to the tool holder;

FIG. 15 shows a sectional view of the tool holder according to FIG. 13, where the sleeve is mechanically fixated by threaded pins with a conical dome;

FIG. 16 shows a sectional view of the tool holder according to the invention, comprising a slotted sleeve, which receives the balls, and where the sleeve is provided with locking grooves and held at the tool holder by additional balls and threaded pins;

FIG. 17 shows a sectional view of the tool holder according to the invention, comprising a conical spring for a pullout preventer without clearance;

FIG. 18 shows a sectional view of the tool holder according to the invention, comprising a length adjustment screw, which is formed from rubber elastic material;

FIG. 19 shows a sectional view of the tool holder according to the inven-tion, comprising a length adjustment screw, which comprises an element made of rubber elastic material;

FIG. 20 shows a sectional view of the tool holder according to the inven-tion, comprising a minimum volume lubrication, balls as locking elements, and a membrane made of rubber elastic material;

FIG. 21 shows a sectional view and a side view of the tool holder according to FIG. 20 according to the invention with a tangential disposition of the locking elements;

FIG. 22 shows an enlarged illustration of a portion of FIG. 20 of the tool holder according to the invention with the membrane and a pressure channel in the transfer piece.

FIG. 23 illustrates a tool holder with an expansion bushing for hydraulically clamping a tool in a longitudinal sectional view;

FIG. 24 illustrates the expansion bushing of FIG. 23 in a blown up sectional view;

FIG. 25 illustrates the expansion bushing in a perspective view;

FIG. 26 illustrates a view of the expansion bushing from behind;

FIG. 27 illustrates a detail view of the expansion bushing in a partial sectional view;

FIG. 28 illustrates the detail view A of FIG. 24;

FIG. 29 illustrates a first embodiment of a clamping system with tool holder, expansion bushing and tool in a sectional view;

FIG. 30 illustrates a second embodiment of a clamping system with tool holder and tool in a sectional view;

FIG. 31 illustrates a third embodiment of a clamping system with tool holder, reduction sleeve in a sectional view; and

FIG. 32 illustrates a fourth embodiment of a clamping system with tool holder, collet and tool in a perspective sectional view.

FIG. 33 illustrates a further embodiment in form of a roller clamping chuck.

DESCRIPTION OF THE INVENTION

FIG. 1 shows the tool holder 1 schematically in a sectional view and an exemplary end mill cutter 2, which are disposed relative to one another with respect to a rotation axis 3. The tool holder 1 thus comprises at least two, preferably three or four, balls 4. The ball is thus disposed in a support bore hole 5, which is disposed perpendicular to the rotation axis 3, and thus to the longitudinal axis in the sleeve section 6 of the tool holder 1. Said support bore hole 5 is a pass-through bore hole and extends from the outside of the sleeve section 6 to the inner circumferential surface of the receiver opening 7, which is disposed concentric with the rotation axis 3 in the tool holder 1. The front support side 8 of the support bore hole 5 is provided in the shape of a spherical cap or configured according to the ball shape of the ball 4, so that the ball 4 partially protrudes into the inner cavity of the receiver opening 7. The ball 4 is held by a threaded pin 9 in its forward position, thus in a position protruding into the inner cavity of the receiver opening 7. Thus, the support bore hole 5 comprises an inner thread corresponding to the outer thread of the threaded pin 9. Thus, the length of the threaded pin 9 does not protrude beyond the outer surface of the sleeve section 6. The threaded pin 9 thus comprises a hexagonal hole 10 for an Allen wrench. The end mill cutter 2 comprises the helical locking grooves 13, 14 on its cylinder shaft 11 proximal to the face 12. They comprise a ball shaped profile, which corresponds to the ball shape of the ball 4. In order to completely clamp the end mill cutter in the tool holder, the tool holder has to be rotated according to the rotation direction 15 during insertion of the end mill cutter, so that the end mill cutter 2 is rotated into the receiver opening 7 in a helical motion until the end mill cutter 2 has reached a stop.

FIG. 2 schematically illustrates a tool holder 1 in a sectional view, in which the end mill cutter 2 is completely clamped in. The end mill cutter 2 is disposed up to its stop with its cylindrical shaft 11 in the receiver opening 7. Thus, the ball 4, which is supported by the threaded pin 9, engages the locking groove 13 or 14. In this graphic sectional view, the cylinder shaft 11 is press fitted in the receiver opening 7, this means, the induction coil (not shown in the drawing) is turned off and the shrink fit chuck of the tool holder 1 is cooled down and shrunk back to its original size. As clearly visible in FIG. 2, an axial movement of the end mill 2 along the rotation axis 3 cannot be performed, since the ball 4 is located in the ball shaped locking groove 13 or 14 in the cylinder shaft 11, so that a movement along the rotation axis 3 is blocked. Thus, the interaction between the ball 4 and the locking groove 13 or 14 is depicted in the form of a lock. In order to remove the end mill 2 cutter from the tool holder 1, the end mill 2 after switching on the induction coil only has to be rotated against the rotation direction 15 (re. FIG. 1), and pulled in axial direction along the rotation axis 3 out of the tool holder 1.

In the subsequent figures, viable embodiments are illustrated, showing how the pullout preventer is configured in other state of the art clamping tools.

FIG. 3 shows a typical draw-in collet chuck with cap nut with the pullout preventer with the locking grooves and balls in a schematic sectional view.

FIG. 4 shows a high precision chuck with the pullout preventer according to the invention through locking grooves and balls.

FIG. 5 shows a typical hydraulic expansion chuck with the pullout preventer according to the invention through locking grooves and balls in a schematic sectional view.

FIG. 6 shows a tool holder provided as shrink fit chuck in a schematic sectional view, where the end mill cutter is bolted to the tool through a thread 16. Through this threaded connection, which is configured with a left pitch direction for a left grooved tool, and a right pitch direction for a right grooved tool, an axial pullout prevention of the tool from the tool holder is implemented.

FIG. 7 shows a shrink fit chuck in a schematic sectional view with locking elements in the form of balls 4, which are held in the respective support bore holes 5 with threaded pins 9. The threaded pin 9 thus comprises a blunt face.

FIG. 8 shows a shrink fit chuck with locking elements configured as balls 4 in a purely schematic sectional view, where the balls are held in the support bore holes 5 by threaded pins 9. The threaded pin 9 comprises a recess 17 on the face receiving the ball 4. The recess 17 is configured as a dead hole or e.g. configured as bushing with an interior hexagonal shape corresponding to the diameter of the ball.

FIG. 9 shows a shrink fit chuck with locking elements provided as balls 4 in a purely schematic sectional view, where the balls are held in the support bore holes 5 by alignment pins 18. Due to the press fit between the alignment pin 18 and the support bore hole 5, the locking elements provided as balls 4 are fixated in their position.

FIG. 10 shows a shrink fit chuck with one-piece locking elements 19 in a purely schematic sectional view. The locking element 19 is a threaded pin, which comprises a semi-spherical head 20 at one of its faces.

FIG. 11 shows a shrink fit chuck with a one-piece locking element 19 in the support bore holes 5 in a purely schematic view. The one-piece locking elements 19 are alignment pins, which are connected to the shrink fit chuck through a press fit. The one-piece locking elements 19 comprise a semi-spherical head 20 on one of their faces.

FIG. 12 shows a shrink fit chuck with locking elements in the form of balls 4 in a purely schematic sectional view. The balls 4 are supported in a ball retainer 21. Thus, the ball retainer 21 is disposed at the bottom of the receiver opening 7. Adjacent thereto, there is a sleeve 22. In the retainer 21, the balls 4 are recessed, which are pressed by the retainer to the radial outside. Thus the balls 4 are thus pressed against a shoulder, which is disposed between the receiver opening 7 and a rotation relief at the end of the receiver opening 7. The balls 4 can be radially supported at said shoulder. When the tool is shrunk in, the balls 4 are supported towards the inside and can secure the tool 2 as well as the sleeve 22 against an axial pullout.

FIG. 13 shows a shrink fit chuck with balls 4 in a purely schematic sectional view, where the balls are disposed in a sleeve 22 in the left section of the sleeve and in the receiver opening 7. The left section of the sleeve 22 thus functions as a ball retainer for the balls 4. The support bore holes 5 for the balls 4 in the sleeve 22 comprise a smaller diameter with reference to the inner cylindrical circumferential surface of the sleeve 22, than the diameter of the balls or the diameter of the support bore hole. Thus, the balls 4 can protrude into the inner cavity but they cannot fall in. The sleeve 22 is either shrunk or pressed into the chuck.

FIG. 14 shows a shrink fit chuck with balls 4 in a sleeve 22 in a purely schematic sectional view. The sleeve 22 is connected to the sleeve section 6 by a weld 23. The weld of the sleeve 22 with the shrink fit chuck can thus be performed in spots in sections or annular as a closed- or Y-weld.

FIG. 15 shows a shrink fit chuck with balls 4 in a sleeve 22 in a purely schematic sectional view. In this embodiment, the sleeve 22 is fixated to the tool holder by threaded pins 24. Thus, the threaded pins 24 e.g. comprise a conical cap. Certainly also other embodiments, like e.g. a ball head, are possible. The sleeve 22 comprises indentations 25 corresponding to the face configuration of the threaded bolts 24, where said indentations are configured corresponding to the face cap configuration of the threaded pins 24. In the present embodiment, said indentations 25 are configured conical. In order to fixate the sleeve 22 at the tool holder, at least one threaded pin 24 with a conical face configuration or with an overall conical configuration is necessary. Preferably, three, in particular four threaded bolts for fixating the sleeve 22 are disposed at the tool holder.

FIG. 16 shows a shrink fit chuck with the locking elements provided as balls 4, disposed in the sleeve 22, in a purely schematic sectional view. The sleeve 22 is thus configured thicker than in the preceding figures. Therefore, the sleeve 22 is slotted (not shown in the drawing). In this embodiment, the sleeve 22 is also connected to the tool holder by balls. Thus, locking grooves 27 corresponding to the balls are disposed in the left portion of the sleeve 22, where said grooves have a profile corresponding to the balls. The same way as the tool is axially fixated in the shrink fit chuck through the interaction of locking elements and locking grooves, the sleeve 22 is axially fixated through balls 26 as locking elements with locking grooves 27 in the outer circumferential surface of the sleeve 22. The balls 26 are thus disposed in support bore holes 28, which in turn connect threaded pins 29 amongst one another by a thread. Also in this case, the support bore hole 28 comprises a smaller diameter in the inner portion in the direction towards the receiver opening 7, than the diameter of the support, which corresponds to the ball diameter of the ball 26. Thus, the balls 26 cannot fall into the interior cavity, but they protrude into it.

FIG. 17 shows a shrink fit chuck with an axial pullout preventer according to FIG. 2 in a purely schematic sectional view. Additionally, the tool holder comprises a conical spring 30, which is disposed between the face side 12 of the cylinder shaft 11 of the end mill cutter 2 and the bottom 31 of the receiver opening 7. The compression spring provided as a conical spring 30 thus presses onto the face 12 of the end mill 2 cutter in the direction of the rotation axis 3 out of the tool holder 1. Thus, a possible clearance or manufacturing tolerances of the locking grooves in the circumferential surface of the cylinder shaft 11 and the respective position of the balls 4 in the tool holder 1 are eliminated, in as far as the end mill cutter 2 is additionally locked in axial direction by the force of the conical spring 3. Thus, also a small clearance between the axial pullout preventer and the tool can be eliminated. Thus, there is no risk to additionally damage the cutting edges of the tool during operation, due to small manufacturing tolerances.

FIG. 18 shows a shrink fit chuck with the locking elements in the form of balls 4 in a purely schematic sectional view. Herein, a pullout prevention of the tool without clearance is performed after shrinking in through the use of a length adjustment screw 32, which is preferably made of a rubber elastic material. Corresponding to the length adjustment screw 32, a corresponding inner thread 33 is formed in the tool holder. In FIG. 18, another embodiment for the path of the locking groove is shown. In this embodiment, the locking groove 34 is provided in the shape of an “L”, but starting at the face 12 of the cylinder shaft 11. Thus, a quasi bayonet lock for an axial safety is provided as a pullout safety for the tool from the tool holder.

FIG. 19 shows a shrink fit chuck from FIG. 18 in a purely schematic sectional view, wherein an elastic element 35 is integrated therein, concentric to the length adjustment screw 32. In this case, the elastic element 35 is preferably made of a rubber elastic material. The pullout prevention without clearance is performed through the compression force, which is imparted through the length adjustment screw 32 to the elastic element 35 through the face 12 to the end mill cutter 2.

FIG. 20 shows a shrink fit chuck with a minimum volume lubrication (MMS) in a purely schematic sectional view. The axial pullout prevention is performed by locking elements 36, which are in turn provided as balls. Concentric to the rotation axis in the interior of the shrink fit chuck, there is a movable tube 37, which is the transfer piece for the minimum volume lubrication. The tube 37 is pressed against the tool shaft (not shown in the drawing) due to the spring force of a coil spring 38. In FIG. 20, two possible end positions of the tube 37 are shown. The contact surface of the tube disposed on the right with the tool shaft is provided conical in the shape of a radial tubular flange 39. The coil spring 38 is thus concentrically permeated by the tube 37. The coil spring 38 is disposed between the bottom 31 and the cone section shaped circumferential surface of the tube 37 at the radial neck flange. FIG. 21 illustrates the tangential disposition of the locking elements 36 in the tool holder along the section line A-A of FIG. 20 in a purely schematic sectional view. FIG. 22 shows an enlarged detail of FIG. 20, which is marked by a dashed line. In a radial neck flange 39 of the tube 37, pass-through bore holes 40 are disposed, which ex-tend from the inner diameter of the tube 37 to the outer circumferential surface 41 of the radial tubular flange 39. Along the cylindrical circumferential surface 41 of the radial tubular flange 39 of the tube 37, a concentric cylinder surface shaped recess 42 is disposed, whose width is preferably smaller than the width of the cylindrical circumferential surface 41 of the tubular flange 39. Corresponding to the recess 42, an annular membrane 43 formed as a section of an enveloping surface of a cylinder is disposed, which is formed flush with the outer cylindrical circumferential surface 41 of the tubular flange 39. The membrane 43 is thus preferably formed from a rubber elastic material. Said membrane 43 along the circumferential surface 41 seals the tube 37 against the wall of the receiver opening 7 of the shrink fit chuck. The bore holes 40, which radially lead to the inside of the membrane 43, pass the air pressure onto the membrane 43, which is thus pressed against the wall 7 of the bore hole. Through the pressure buildup, the membrane cambers in radial direction and thus attaches to the inner circumferential surface of the receiver opening 7 of the tool holder. Thus, the tube 37 is secured as a transfer piece for the minimum volume lubrication against axial displacement. Through the movable tube 37, the lubricant mist can be conducted to the tool without loss.

FIG. 23 illustrates a longitudinal sectional view of a tool holder 50 illustrated as HSK tool holder including a rotation symmetrical base element 51 and an expansion bushing 52 arranged in the base element 51 for receiving the cylindrical shaft of a tool that is not illustrated. The base element 51 includes a cylindrical front portion 53 with a receiver opening 54 for the expansion bushing 52 and a conical rear portion for reception in an operating spindle of a machine tool. Between the cylindrical front portion 53 and the conical rear portion 55 an engagement groove 56 is provided at the outside of the base element 51.

The expansion bushing 52 that is separately illustrated in FIG. 24 includes two circumferential recesses 57 at its outside that are offset from one another and an annular shoulder 58 at its front end. Between the recesses 57 and the inner wall of the base element 51 in the portion of the receiver openings 54 pressure cavities 59 that are illustrated in FIG. 23 are defined for receiving a pressure fluid. The expansion bushing 52 is advantageously firmly connected at its forward and rear end with the base element 51. It can be soldered to the base element 51 or it can be permanently connected with the base element 51 in another manner. The pressure cavities 59 are connected with a pressure cavity arranged in the base element 51 through channels in the base element 51 that are not illustrated herein, wherein the volume of the pressure cavity is variable for example through a piston that is adjustable through a bolt. Through adjusting the piston through the bolt, a pressure of the pressure fluid arranged in the pressure cavity and in the pressure chamber 59 can be increased and thus the expansion bushing 52 can be pressed radially inward. Through the known arrangement which is therefore not illustrated the expansion bushing 52 can be evenly pressed against the cylindrical shaft of a tool to be clamped that has been inserted into the expansion bushing 52 which facilitates a centric and full surface clamping with high clamping force.

At the inside of the expansion bushing 52 inward protruding locking elements 61 are provided in a rear portion 60 that has an expanded inner diameter, wherein the locking elements extend like a thread turn of a nut and engage corresponding opposite elements 62 at a cylindrical tool shaft 63 of a tool 64 that is illustrated in FIG. 29. The opposite elements 62 are configured like a thread turn of a bolt. Through the locking elements 61 engaging respective opposite elements 62 at the tool 64 an extraction safety is provided which prevents an axial extraction of the tool 64 that is caused for example by vibrations during processing.

In the illustrated embodiment the locking elements 61 are configured as protrusions with semi circular cross sections extending in circumferential direction in helical shape. As apparent from FIG. 26 three protrusions are provided in the embodiment that are spaced with even angular offsets in circumferential direction which are provided as locking elements 61 in the form of thread turns of a nut, wherein the locking elements extend at an inner wall of the expansion bushing 52 like a three turn inner nut thread respectively with identical pitch. The opposite elements matching the locking elements 61 are configured as locking grooves which are configured like a three path bolt thread at an outside of the cylindrical tool shaft 63 of a tool 64 starting at the rear face and extending in a helical shape along the circumferential surface.

The expansion bushing 52 is advantageously produced according to the method according to the invention from a metal solid material block, (for example a solid cylinder) by producing a recess through a material removing electrical discharge machining method like e.g. EDM or EDCM, wherein the locking elements 61 are left out in the cylindrical recess as inward extending protrusions when generating the recess.

For inserting a tool into the tool holder 50 the tool when inserted into the tool holder 50 initially has to be rotated so that the locking elements 61 come into engagement at the expansion bushing 52 with the respective opposite elements 62 at the tool 64. Then the expansion bushing 52 can be loaded with pressure fluid from the outside. The pressure presses the expansion bushing 52 in inward direction which clamps the tool 64. Through the form locking engagement of the locking elements 61 in the associated opposite elements 62 an axial extraction of the tool 64 from the tool holder 50 can be prevented.

FIG. 29 illustrates a clamping system with a tool holder 50, an expansion bushing 52 and a tool 64 configured for example as a mill or a drill. Differently from the embodiments in FIGS. 23-28 the expansion bushing 52 only includes a recess 57 at its outside for forming a pressure cavity 59. Also in this embodiment inward protruding locking elements 61 are provided at the inside of the expansion bushing 52, wherein the locking elements are provided as helically extending protrusions for engaging opposite elements 62 configured as locking grooves at the cylindrical tool shaft 63 of a tool 64.

FIG. 30 illustrates another embodiment of the clamping system with tool holder 50 and a tool 64 configured as a mill, drill or similar. In the embodiment the receiver is configured as a shrink fit chuck 65 that is integrally configured with the base element 51. In a tool holder 50 of this type the shrink fit chuck 65 is thermally heated for example through induction which increases the interior diameter of the shrink fit chucks 65. In heated condition a tool 64 is inserted into the shrink fit chuck 65, wherein the ratio of the inner diameter of the shrink fit chuck 65 to the outer diameter of the cylindrical tool shaft 63 is configured so that the tool 64 is firmly supported in the shrink fit chuck 65 during subsequent cooling of the shrink fit chuck 65. In this embodiment inward protruding locking elements 61 are configured at an inside of the shrink fit chuck 65, wherein the locking elements are configured as helical protrusions for engaging the opposite elements 62 configured as locking grooves at the cylindrical tool shaft 63 of a tool 64.

In an additional embodiment illustrated in FIG. 31 the receiver is also configured as a shrink fit chuck 65 that is integrally configured with the base element 51. Herein, however, the tool 64 is clamped within the shrink fit chuck 65 through a reduction sleeve 66. The reduction sleeve 66 is configured in a known manner as a slotted sleeve with plural axial slots and an inner diameter adapted to the outer diameter of the cylindrical tool shaft 63. The reduction sleeve 66 also includes inward protruding locking elements 61 at its inside, wherein the locking elements are configured as helical protrusions for engaging opposite elements 62 at the cylindrical tool shaft 63 of a tool 64 configured as locking grooves. The reduction sleeve 66 furthermore includes helical locking grooves 67 at its outside for engaging locking elements 68 which are formed as inward protruding helical protrusions at the inside of the shrink fit chuck 65. Thus, an extraction safety to prevent axial extraction of the reduction sleeve 66 is implemented.

FIG. 32 illustrates another embodiment in which the receiver is configured as a collet 71 that is arranged within a receiving opening 69 of the base element 51 and deformable through a clamping element 70. The collet 71 includes an outer cone surface 72 for contacting an inner cone surface 73 of the

receiving opening 69. The cone surfaces 72 and 73 are adjusted to one another so that the collet 71 can be compressed in inward direction through axial movement so that it clamps a cylindrical tool shaft 63 of a tool 64. The collet 71 also includes inward protruding locking elements 61 at its inside, wherein the locking elements are configured as helical protrusions for engaging opposite elements 62 at the cylindrical tool shaft 63 of a tool 64 configured as locking grooves. The axial movement of the collet 71 is also provided through the clamping element 70 which is configured herein as a threaded ring that is threaded onto an external thread at a front end of the base element 51.

In another embodiment which is illustrated in FIG. 33, the tool holder is configured as a so-called roller clamping chuck, which is a collet-like clamping chuck. Similar to the embodiment illustrated in FIG. 30, the tool holder 50 is provided with a clamping chuck 79 to receive the tool. On a front portion of the clamping chuck 79 a clamping element or nut 70 is arranged which is typically rotatably supported through a needle bearing 80 or another roller bearing wherein the at least partially deformable clamping element or nut 70 can impart a clamping pressure onto the clamping chuck 79 by being rotated. The needle bearings are supported within a bearing cage roll on the tapering inner surface 81 of the clamping element or nut 70 and on a tapering outer surface 82 of the front portion of the clamping chuck. When the clamping element or nut 70 is turned then the space between the tapering inner surface 81 of the clamping element or nut 70 and the tapering outer surface 82 of the front portion of the chuck 79 is reduced and the clamping nut presses against the front portion of the clamping chuck through the needle rollers in order to press the clamping chuck against the tool shaft for tightening the tool. The inner circumferential face of the clamping chuck 79 of the tool holder 50 is provided with longitudinal grooves 84 which are parallel to the longitudinal axis of the tool holder 50 which serve to make the clamping chuck portion deformable so that the tool shaft can be clamped when the clamping element or nut 70 is tightened.

In addition the locking elements 85 formed in the inner circumferential face 83 can be seen from FIG. 33 which are co-acting with the locking grooves 86 at the shaft 87 of the tool 88. Of course the number of locking elements 85 corresponds with the number of locking grooves 86 and the circumferential distance between the locking elements is the same as the distance between the locking grooves.

The invention is certainly not limited to HSK tool holders also SK-, WS-, BT-, ABS-, or Capto-interfaces and similar can be accordingly provided at the base element 2.

Claims

1. A combination of a tool holder and a rotation tool, the combination comprising:

a rotation tool having a shaft with an end face and a circumferential surface;

a tool holder having a clamping chuck being a deformable receiver for receiving and clamping the rotation tool in a central axial opening thereof;

a pullout preventer configured to lock said rotation tool in said tool holder against an axial migration out of said central axial opening of said tool holder;

said pullout preventer including at least one locking element, being a part of said tool holder, and at least one locking groove formed in said rotation tool, with said at least one locking groove and said at least one locking element being complementarily formed and disposed to engage one another and to lock said rotation tool against the axial migration out of said tool holder.

2. The combination according to claim 1, wherein said locking element is configured to project inward into said central axial opening in said tool holder and into said locking groove in said shaft of said rotation tool when said rotation tool is mounted in said tool holder.

3. The combination according to claim 2, wherein said at least one locking groove begins at said end face and extends in said circumferential surface from said end face in a straight linear path, in a curved path, in an L-shaped path, or in a composite path with a plurality of segments.

4. The combination according to claim 2, wherein said locking element is a forward head of a locking element being a pin projecting through support bore hole formed in a wall of said tool holder and into said locking groove.

5. The combination according to claim 1, wherein said locking element is integrally formed with said receiver.

6. The combination according to claim 1, wherein said at least one locking element and said at least one locking groove are configured at least as a partial ball head.

7. The combination according to claim 1, wherein said at least one locking groove is one of at least two locking grooves and said at least one locking element is one of at least two locking elements.

8. The combination according to claim 7, wherein said at least one locking groove is one of four circumferentially distributed locking grooves and said at least one locking element is one of four locking elements.

9. The combination according to claim 1, wherein said at least one locking groove has a helical surface path having a left pitch direction for the rotation tool with a left groove, and a right pitch direction for the rotation tool with a right groove.

10. The combination according to claim 1, wherein said clamping chuck is a draw-in collet chuck, a precision chuck, a hydraulic expanding chuck, or a shrink fit chuck.

11. A rotation tool, comprising:

a shaft with an end face and a circumferential surface, and a tool head opposite said shaft;

said shaft being formed for insertion into a tool holder with a clamping chuck for driving rotation of the tool about a rotation axis;

said shaft of said rotation tool being formed with at least one locking groove that begins at said end face and extends in, and terminates in, said circumferential surface; and

said locking groove being formed for engagement by a locking element of the tool holder, that locks the rotation tool against an axial migration out of said tool holder.

12. The rotation tool according to claim 11, wherein said locking groove extends along a path that is non-parallel to the rotation axis in a straight linear path, in a curved path, in an L-shaped path, or in a composite path formed in mutually different shapes that are linearly offset from one another;

13. The rotation tool according to claim 11, wherein said at least one locking groove is formed to receive and mesh with a partial ball head.

14. The rotation tool according to claim 11, wherein said at least one locking groove is one of at least two locking grooves formed in said shaft diametrically opposite one another relative to the rotation axis.

15. The rotation tool according to claim 11, wherein said at least one locking groove has a helical surface path with a left pitch direction of the rotation tool with a left groove, and a right pitch direction for the rotation tool with a right groove.

16. The rotation tool according to claim 11, configured for insertion in a draw-in collet chuck, a precision chuck, a hydraulic expanding chuck, or a shrink fit chuck.

17. A tool holder for a rotation tool, the tool holder comprising:

a clamping chuck formed with a central axial opening for receiving and clamping the rotation tool therein;

a locking element disposed to project into said central axial opening;

said central axial opening forming a receiver for receiving a shaft of a rotation tool therein, wherein the shaft is formed with a locking groove configured to engage with said locking element that projects into said central opening and said locking element is configured to mesh with the locking groove and to lock said rotation tool against an axial migration out of said tool holder.

18. The tool holder according to claim 17, wherein said clamping chuck is formed with at least one support bore hole extending radially from an exterior thereof and into said central axial opening, and a pin configured for insertion into said support bore hole is formed with said locking element that projects into said central axial opening and into the locking groove of the rotation tool when the rotation tool is mounted in the tool holder.

19. The tool holder according to claim 17, wherein said at least one locking element is one of at least two, at least three, or four locking elements projecting into said central axial opening and distributed about a rotation axis of the tool holder.

20. The combination according to claim 17, wherein said locking element is integrally formed with said receiver.