Tool clamping system for a machine tool

Abstract

Tool clamping system for a machine tool, comprising a tool holder (6) for holding a grinding screw (8), a spindle (10) for holding the tool holder (6), wherein an outer cone (12) formed on the spindle (10) abuts an inner cone (14) formed on the tool holder (6), a balancing system (18) arranged in an interior (22) of the spindle (10), wherein a first cover (28) is connected to an end section (30) of the spindle (10), wherein a second cover (34) covering the first cover (28) is connected to an end section (36) of the tool holder (6), and wherein the first cover (28) and the second cover (34) are clamped against each other in the axial direction (A).

Description

[0001] The present invention relates to a tool clamping system for a machine tool, comprising a tool holder for holding a grinding worm, a spindle for holding the tool holder, wherein an outer cone formed on the spindle bears against an inner cone formed on the tool holder, and a balancing system arranged in an interior of the spindle.

[0002] The applicant is aware of tool clamping systems that enable the fully automated clamping of a tool holder to the spindle. The tool holder is automatically pulled onto a taper seat formed by the inner taper described above and the associated outer taper using a collet chuck.

[0003] In addition to repeatable clamping, the automated clamping system also has the advantage that the collet provides additional support for the tool holder, reliably transferring compensating radial forces from the balancing system to the tool holder, thus enabling high-precision balancing. The disadvantage is that such a fully automated solution, with the corresponding collet design, is cost-intensive.

[0004] Against this background, the present invention is based on the technical problem of specifying a tool clamping system for a machine tool which enables manual clamping of the tool holder on the spindle, wherein in particular the quality of balancing by means of the balancing system should not be impaired.

[0005] The technical problem described above is solved by the features of the independent claim. Further embodiments of the invention emerge from the dependent claims and the following description.

[0006] According to the invention, a tool clamping system for a machine tool is specified, comprising a tool holder for holding a grinding worm, a spindle for holding the tool holder, wherein an outer cone formed on the spindle bears against an inner cone formed on the tool holder, and a balancing system arranged in an interior space of the spindle. The tool clamping system is characterized in that a first cover is connected to an end section of the spindle, that a second cover covering the first cover is connected to an end section of the tool holder, and that the first cover and the second cover are clamped against one another in the axial direction in order to enable radial force transmission between the spindle and the tool holder. In this way, for example, compensating radial forces of a balancing weight of the balancing system can be transmitted from the spindle to the tool holder.

[0007] The first and the second cover therefore form a force-locking or frictional connection to each other, whereby the spindle and the tool holder are force-locked to each other in the radial direction in the area of ​​the covers, so that the effect of the balancing system in the area of ​​the covers is transferred via the spindle into the tool holder.

[0008] The covers therefore provide additional radial support for the tool holder on the spindle. Compared to the initially mentioned design of a tool clamping system with an automated collet, the covers used in the invention now replace the radial support effect of the collet, which is no longer present in the invention. Therefore, in particular, the invention does not provide for an automatically operable collet that enables automated clamping of the tool holder on the spindle.

[0009] The grinding worm is not part of the claimed tool clamping system. The tool holder is intended and suitable for accommodating a respective grinding worm to be mounted and, for this purpose, has, for example, a circular cylindrical outer surface suitable for sliding on, clamping, and holding the respective grinding worm.

[0010] It can be provided that a distance, measured in the axial direction, of the outer cone formed on the spindle to the first cover is greater than half the length of the tool holder measured in the axial direction or greater than half the length, measured in the axial direction, of the grinding worm held on the tool holder.

[0011] It can be provided that a distance, measured in the axial direction, of the outer cone formed on the spindle to the second cover is greater than half the length of the tool holder measured in the axial direction or greater than half the length, measured in the axial direction, of the grinding worm held on the tool holder.

[0012] The outer cone of the spindle therefore forms a first radial support of the tool holder on the spindle, while the covers clamped against each other form a second radial support of the tool holder on the spindle.

[0013] The first cover may comprise or be made of a metallic material.

[0014] The second cover may comprise or be made of a metallic material.

[0015] The first cover and the second cover can be resiliently clamped against each other, so that any deformation of the first cover and / or the second cover resulting from the clamping is essentially reversible. A clamping force formed between the first cover and the second cover can therefore be repeatedly applied and released, whereby reliable radial support of the tool holder on the spindle can be achieved by means of the clamped covers even after numerous assembly cycles.

[0016] The second cover can have a collar that extends at least partially in the axial direction, and the collar can enclose the first cover at least partially on its circumference. This allows for a compact structural integration of the cover into the overall structure.

[0017] It can be provided that the collar is a circular collar and that the collar completely encloses the first cover on the circumference.

[0018] In order to achieve the intended function, the first cover and the second cover are designed to be rigid in the radial direction and flexible in the axial direction in order to enable axial clamping.

[0019] The collar of the second cover may have a radial thickness that is at least twice the axial wall thickness of the second cover.

[0020] The first cover may have a collar extending at least partially in the axial direction, wherein the collar of the first cover has a radial thickness that corresponds to at least twice the axial wall thickness of the first cover. The collar of the first cover may be a circular, circumferential collar.

[0021] According to one embodiment of the tool clamping system, it can be provided that a defined contact is formed between an inner side of the second cover facing the first cover and an outer side of the first cover facing the second cover, wherein the defined contact is formed by a shaped element formed at least in sections in the axial direction on the first or second cover, such as a local thickening, a convex bulge, a web or the like.

[0022] In particular, it can be provided that such a shaped element formed in the axial direction protrudes at least in sections in the axial direction or is cantilevered in the axial direction in order to achieve a defined axial contact between the first cover and the second cover.

[0023] According to alternative embodiments, it can be provided that an additional intermediate element or spacer element is arranged between the first cover and the second cover, such as a spacer disk or a spacer element or the like, or that several such intermediate elements or spacer elements are arranged between the first cover and the second cover in order to achieve a defined contact or a defined axial clamping between the first cover and the second cover.

[0024] According to alternative embodiments, it can be provided that a shaped element is formed on both the first cover and the second cover in order to achieve a defined axial contact of the first cover on the second cover.

[0025] It can be provided that abutting surfaces of the first cover and the second cover form a friction pairing which at least reaches a predetermined coefficient of friction for a predetermined axial force in order to prevent radial sliding of the first cover relative to the second cover and vice versa.

[0026] According to one embodiment of the tool clamping system, the shaped element can be a convex bulge formed on the second cover, which, in particular, transitions seamlessly into adjacent regions, such as the collar or the like. It can be provided that the convex bulge transitions freely or continuously into a radius, wherein the radius is at least partially part of the collar.

[0027] The tool clamping system can have a pressure flange which forms an axial stop for receiving the grinding worm, wherein the pressure flange is connected to the tool holder, in particular screwed.

[0028] The second cover, the tool holder and the pressure flange can be removed from the spindle as a unit and mounted on the spindle as a unit, whereby in the event of a tool change a pre-assembled unit consisting of a further second cover, a further tool holder, a further pressure flange and a new grinding worm can be pushed onto the spindle.

[0029] The first lid and the second lid can be screwed together.

[0030] The first cover can be screwed to the spindle.

[0031] The second cover can be screwed to the tool holder.

[0032] The tool holder can be screwed to the spindle.

[0033] The tool holder can have a cylindrical receiving surface for receiving the grinding worm.

[0034] The tool holder can have an axial stop in the form of a circular collar for the axial positioning of the grinding worm.

[0035] The invention is explained in more detail below with reference to exemplary embodiments of the drawings. They show schematically: Fig. 1 a tool clamping system according to the invention for a machine tool in a partial section; Fig. 2A two covers of the tool clamping system Fig. 1 in a partial section; Fig. 2B two covers of the tool clamping system made of Fig. 1 in a partial section in a clamped state; Fig. 3 a force flow in the tool clamping system according to Fig. 1; Fig. 4 a force flow in a tool clamping system not according to the invention.

[0036] Fig. 1 shows a tool clamping system 2 according to the invention for a machine tool. The tool clamping system 2 is shown in a partial section, whereby, to simplify the illustrations, only a region of the tool clamping system 2 arranged above a center line 4, which is designed essentially rotationally symmetrically to the center line 4, is shown.

[0037] The tool clamping system 2 has a tool holder 6 for holding a grinding worm 8. The tool clamping system 2 has a spindle 10 for holding the tool holder 6. The spindle 10 is rotationally driven in a known manner, so that the grinding worm 8 rotates together with the driven spindle 10 during machine operation.

[0038] An outer cone 12 formed on the spindle 10 rests against an inner cone 14, wherein the inner cone 14 is formed on the tool holder 6.

[0039] The tool holder 6 is screwed to the spindle 10, the screw connection 16 being indicated by the dash-dotted line provided with the reference number 16.

[0040] The tool clamping system 2 has a balancing system 18. The balancing system 18 has four supports 20 opposite the spindle 10 and is accommodated in an interior space 22 of the spindle 10. The balancing system 18 has two adjustable mass elements or balancing weights 24, 26 for balancing the rotating spindle assembly including the tool 8 for grinding operation.

[0041] The tool clamping system 2 has a first cover 28, which is screwed to an end portion 30 of the spindle 10. The screw connection 32 is again indicated by a dot-dash line.

[0042] The tool clamping system has a second cover 34, which is screwed to an end section 36 of the tool holder 6. The screw connection 38 is indicated by a dot-dash line.

[0043] The first cover 28 and the second cover 34 are clamped against each other in the axial direction. This creates a frictional connection in the radial direction between the first cover 28 and the second cover 34, so that the tool holder 6 is supported radially on the spindle 10. The radial direction R is oriented perpendicular to the center line 4, while the axial direction A is oriented parallel to the center line 4.

[0044] The radial support of the tool holder 6 on the spindle 10 in the area of ​​the covers 28, 34 results in a compensating radial force of the balancing weight 24 of the balancing system 18 being transferred from the spindle 10 to the tool holder 6. This effect will be discussed later with reference to the Fig. 3 and Fig. 4 explained in more detail.

[0045] The second cover 34 has a collar 40 extending in the axial direction A. The second cover 34 completely encloses the first cover 28 circumferentially by means of the collar 40. The collar 40 is a circular, circumferential collar.

[0046] The collar 40 of the second cover 34 has a radial thickness D1 that is greater than twice an axial wall thickness W1 of the second cover 34.

[0047] The first cover 28 has a collar 42 extending in the axial direction. The collar 42 of the first cover 28 has a radial thickness D2 that is greater than twice the axial wall thickness W2 of the first cover 28. The collar 42 is a circular, circumferential collar.

[0048] A defined contact surface 48 is formed between an inner side 44 of the second cover 34 facing the first cover 28 and an outer side 46 of the first cover 28 facing the second cover 34.

[0049] The defined abutment 48 is formed by a shaped element formed at least in sections in the axial direction on the second cover 34 - specifically in the form of a convex bulge 50 of the second cover 34.

[0050] Like the Fig. 2A and Fig. 2B, the convex bulge 50 transitions seamlessly into a radius which at least partially delimits the collar 40.

[0051] In Fig. 2A, the covers 28 and 34 are shown in profile superimposed without any deformation being shown.

[0052] How Fig. 2A, the second cover 34 and the first cover 28 are shown overlapping in the area of ​​the bulge 50, which is intended to illustrate that in the fully assembled state, an excess is formed in this area, which defines the resulting tension between the first cover 28 and the second cover 34. Because of the excess, the covers 28, 34 deform during assembly, so that the covers 28, 34 are resiliently clamped against each other, as in Fig. 2B.

[0053] The force acting in the axial direction due to the resilient elastic tension between the covers 28, 34 creates a frictional engagement in the radial direction, so that the tool holder 6 is frictionally supported against the spindle 10 in the area of ​​the defined contact 48.

[0054] Fig. 3 shows an example and schematically a force curve for transmitting a compensating radial force F of the balancing weight 24 of the balancing system 18. The force flow represented by the solid line runs via the support 20 into the first cover 28 and is guided via the defined system 48 into the second cover 34, so that the compensating radial force F is transmitted from the spindle 10 to the tool holder 6.

[0055] Without the radial supporting effect of the first and second cover 28, 34, a force flow according to Fig. 4, where Fig. 4 shows a device V not according to the invention without the previously described covers. As can be seen from this illustration, the compensating radial force is not transferred from the spindle to the tool holder, thus impairing the overall effectiveness of the balancing system.

[0056] The tool clamping system 2 has a pressure flange 52, which forms an axial stop for receiving the grinding worm 8 ( Fig. 1). The pressure flange 52 is screwed to the tool holder 6, as indicated by the screw connection 54 in the form of the dashed line.

[0057] The second cover 34, the tool holder 6, the pressure flange 52, and the grinding worm 8 can be removed as a unit from the spindle 10 and mounted as a unit on the spindle 10. In the event of a tool change, a preassembled unit consisting of another second cover, another tool holder, another pressure flange, and a new grinding worm can be pushed onto the spindle.

[0058] The tool holder 6 has a cylindrical receiving surface 56 for receiving the grinding worm 8. The tool holder 6 also has an axial stop 58 in the form of a circular collar for axially supporting the grinding worm 8. REFERENCE SYMBOL 2 tool clamping system 4 Center line 6 tool holder 8 grinding worm 10 spindle 12 outer cones 14 inner cones 16 screw connection 18 Balancing system 20 Support 22 Interior 24 Balancing weight 26 Balancing weight 28 first lid 30 final section 32 screw connection 34 second lid 36 final section 38 screw connection 40 collars 42 collar 44 Inside 46 Outside 48 defined facility 50 convex bulge 52 Pressure flange 54 screw connection 56 recording area 58 axial stop A axial direction R radial direction F radial force V Device (not according to the invention)

Claims

[1] Tool clamping system for a machine tool, - with a tool holder (6) for holding a grinding worm (8), - with a spindle (10) for holding the tool holder (6), - wherein an outer cone (12) formed on the spindle (10) bears against an inner cone (14) formed on the tool holder (6), - with a balancing system (18) arranged in an interior space (22) of the spindle (10), characterized by , - that a first cover (28) is connected to an end portion (30) of the spindle (10), - that a second cover (34) covering the first cover (28) is connected to an end section (36) of the tool holder (6) and - that the first cover (28) and the second cover (34) are clamped against each other in the axial direction (A) in order to enable a radial force transmission between the spindle (10) and the tool holder (6). [2] Tool clamping system according to claim 1, characterized by , that - the second cover (34) has a collar (40) extending at least partially in the axial direction (A), and the collar (40) surrounds the first cover (28) at least partially on the circumference, - in particular that the collar (40) is a circular collar (40) and the collar (40) completely encloses the first cover (28) on the circumference. [3] Tool clamping system claim 2, characterized by , that the collar (40) of the second cover (34) has a radial thickness (D1) which corresponds to at least twice an axial wall thickness (W1) of the second cover (34), and / or the first cover (28) has a collar (42) extending at least partially in the axial direction (A), wherein the collar (42) of the first cover (28) has a radial thickness (D2) which corresponds to at least twice an axial wall thickness (W2) of the first cover (28). [4] Tool clamping system according to one of the preceding claims, characterized by , that - a defined contact surface (48) is formed between an inner side (44) of the second cover (34) facing the first cover (28) and an outer side (46) of the first cover (28) facing the second cover (34), - wherein the defined contact (48) is formed by a shaped element (50) formed at least in sections in the axial direction on the first cover (28) or the second cover (34), such as a local thickening, a convex bulge, a web or the like. [5] Tool clamping system claim 4, characterized bythat the shaped element (50) is a convex bulge (50) formed on the second cover (34), which in particular merges seamlessly into adjacent regions, such as the collar (40) or the like. [6] Tool clamping system according to one of the preceding claims, characterized by that a pressure flange (52) is provided which forms an axial stop for receiving the grinding worm (8), wherein the pressure flange (52) is connected to the tool holder (6), in particular is screwed. [7] Tool clamping system according to claim 6, characterized by , that - the second cover (34), the tool holder (6) and the pressure flange (52) can be removed as a unit from the spindle (10) and mounted as a unit on the spindle (10), - In the event of a tool change, a pre-assembled unit consisting of a further second cover, another tool holder, another pressure flange and new grinding worm can be pushed onto the spindle. [8] Tool clamping system according to one of the preceding claims, characterized by , that - the first cover (28) and the second cover (34) are screwed together and / or - the first cover (34) is screwed to the spindle (10) and / or - the second cover (34) is screwed to the tool holder (6). [9] Tool clamping system according to one of the preceding claims, characterized by that the tool holder (6) is screwed to the spindle (10). [10] Tool clamping system according to one of the preceding claims, characterized by , that - the tool holder (6) has a cylindrical receiving surface (56) for receiving the grinding worm (8) and / or - the tool holder (6) has an axial stop (58) in the form of a circular collar (58) for the axial engagement of the grinding worm (8).

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