TOOL HOLDER AND TOOL SYSTEM

Abstract

Tool holder comprising a tool receptacle, a machine interface, and a sensor receptacle. The tool receptacle is configured to releasably receive a tool having at least one cutting edge for machining a workpiece. The machine interface is configured to enable the tool holder to be fastened to a machine tool. In the sensor receptacle, a sensor is arranged that is configured to generate a measurement signal that is dependent on a force acting on the tool holder The sensor receptacle is spaced apart from both the tool receptacle and the machine interface, so that the sensor is neither in direct contact with the tool nor in direct contact with the machine tool when the tool is accommodated in the tool receptacle and the tool holder is fastened to the machine tool.

Claims

1. A tool holder, comprising: a tool receptacle that is configured to releasably receive a tool having at least one cutting edge for machining a workpiece; a machine interface that is configured to enable the tool holder to be fastened to a machine tool; and a sensor receptacle in which a sensor is accommodated that is configured to generate a measurement signal that is dependent on a force acting on the tool holder, wherein the sensor receptacle is spaced apart from both the tool receptacle and the machine interface, so that the sensor is neither in direct contact with the tool nor in direct contact with the machine tool when the tool is accommodated in the tool receptacle and the tool holder is fastened to the machine tool.

2. The tool holder according to claim 1, wherein a sensitive axis of the sensor, along which the sensor has its main sensitivity, is oriented at an acute angle relative to a longitudinal axis of the tool holder.

3. The tool holder according to claim 2, wherein the sensitive axis coincides with a direction of a resultant force resulting from the force acting on the tool holder, or is oriented at an angle of at most 10° to said direction.

4. The tool holder according to claim 2, wherein the tool holder comprises a first abutment surface and a second abutment surface that extends transversely to the first abutment surface, and wherein the sensitive axis of the sensor is oriented at a first acute angle relative to the first abutment surface and at a second acute angle relative to the second abutment surface.

5. The tool holder according to claim 4, wherein the second contact surface is oriented parallel to the longitudinal axis of the tool holder.

6. The tool holder according to claim 1, wherein the sensor is arranged in a force shunt of the tool holder.

7. The tool holder according to claim 1, wherein the sensor receptacle comprises a pocket-shaped receptacle that encloses the sensor from at least four sides.

8. The tool holder according to claim 1, further comprising a clamping device that is configured to clamp the sensor in the sensor receptacle.

9. The tool holder according to claim 1, wherein the clamping device is configured to be at least partially detachable from the tool holder.

10. The tool holder according to claim 9, wherein the clamping device comprises a first wedge element and a second wedge element.

11. The tool holder according to claim 10, wherein the first wedge element abuts the sensor with a first side surface and abuts a wedge surface of the second wedge element with a second side surface that is arranged opposite to the first side surface, and wherein the second side surface and the wedge surface are oriented at an acute angle relative to the first side surface.

12. The tool holder according to claim 11, wherein the sensor receptacle comprises a support that is configured to support the first wedge element.

13. The tool holder according to claim 1, wherein a sensitive axis of the sensor, along which the sensor has its main sensitivity, is oriented parallel to a longitudinal axis of the tool holder.

14. The tool holder according to claim 1, wherein the tool receptacle is arranged at a face end of the tool holder and is configured as a pot-shaped recess in the tool holder.

15. The tool holder according to claim 1, wherein the sensor comprises a force transducer.

16. The tool holder according to claim 1, wherein the sensor comprises a cable that is routed out of the sensor receptacle through a cable duct extending inside the tool holder.

17. A tool system, comprising: a tool having at least one cutting edge for machining the workpiece; and a tool holder; wherein the tool holder comprises: a tool receptacle that is configured to releasably receive the tool; a machine interface that is configured to enable the tool holder to be fastened to a machine tool; and a sensor receptacle in which a sensor is accommodated that is configured to generate a measurement signal that is dependent on a force acting on the tool holder, wherein the sensor receptacle is spaced apart from both the tool receptacle and the machine interface, so that the sensor is neither in direct contact with the tool nor in direct contact with the machine tool when the tool is accommodated in the tool receptacle and the tool holder is fastened to the machine tool.

18. The tool system according to claim 17, wherein the tool comprises a tool cartridge having a cutting insert receptacle in which a cutting insert is arranged on which the at least one cutting edge is formed, and wherein the tool cartridge is detachably fastened to the tool holder in the tool receptacle by means of at least one fastening element.

19. The tool system according to claim 17, wherein the tool comprises a cutting insert on which the at least one cutting edge is formed, wherein the cutting insert comprises a clamping portion that is inserted into and releasably fastened in the tool receptacle of the tool holder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] FIG. 1 shows a perspective view of a first embodiment of the tool system, comprising the tool holder;

[0066] FIG. 2 shows an exploded view of the first embodiment of the tool system shown in FIG. 1;

[0067] FIG. 3 shows a side view of the first embodiment of the tool system shown in FIG. 1;

[0068] FIG. 4 shows another side view of the first embodiment of the tool system shown in FIG. 1;

[0069] FIG. 5 shows a sectional view of a detail of the first embodiment of the tool holder shown in FIG. 1;

[0070] FIG. 6 shows a perspective view of a second embodiment of the tool system according to the invention, comprising the tool holder;

[0071] FIG. 7 shows an exploded view of the second embodiment of the tool system shown in FIG. 6; and

[0072] FIG. 8 shows a sectional view of the second embodiment of the tool system shown in FIG. 6.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0073] FIGS. 1-4 show a first embodiment of the tool system in a perspective view, an exploded view and two side views. The tool system is denoted therein in its entirety with the reference numeral 100.

[0074] The tool system 100 comprises a tool holder 10 and a tool 12. The tool 12 is detachably fastened to the tool holder 10. For this purpose, the tool holder 10 comprises a pocket-shaped tool receptacle 14 in which the tool 12 can be arranged in a precisely defined manner. In the present embodiment, four screws 16 serve to fasten the tool 12 in the tool receptacle 14. However, it goes without saying that more or fewer screws may also be used to fasten the tool 12 to the tool holder 10. Likewise, other fastening means for fastening the tool 12 to the tool holder 10 are conceivable.

[0075] The tool 12 itself comprises a cutting insert holder 18 and a cutting insert 20 detachably arranged therein. The cutting insert 20 is typically a cutting insert or a socalled indexable insert made of carbide. The cutting insert 20 comprises at least one cutting edge 22 for machining a workpiece. In this case, it is a cutting edge 22 with a straight cutting edge. However, the cutting insert 20 can just as well comprise a curved cutting edge or several different cutting edges for machining the workpiece.

[0076] In the herein shown embodiment, the tool 12 is configured as a turning tool which is particularly suitable for groove turning. However, the present disclosure is not limited to this type of configuration of the tool 12.

[0077] The cutting insert holder 18 is configured as a tool cartridge, which is particularly advantageous for space reasons if several such tool systems are used simultaneously within a machine tool. The fixation of the cutting insert 20 in the cutting insert holder or the tool cartridge 18 is carried out here by means of a further clamping screw 24. However, other fixing means for clamping the cutting insert 20 are also conceivable. In any case, it is advantageous if the cutting insert 20 can be released separately from the tool cartridge 18 without the latter in turn having to be released from the tool holder 10. In this way, the cutting insert 20 can be replaced very easily by a new one when it is worn out, without having to remove the entire tool 12 from the tool holder 10 for this purpose.

[0078] The tool holder 10 further comprises a machine interface 26 that allows the tool holder 10 to be fastened to a machine tool. The machine interface 26 may include a part of the housing of the tool holder 10. Likewise, further fastening means, such as screws, may belong to this machine interface 26. Further, in the present embodiment, the machine interface 26 includes a coolant port 28 disposed at the rear side of the tool holder 10.

[0079] The tool holder 10 further comprises a sensor receptacle 30, in which a sensor 32 is detachably mounted. As can be seen in particular from FIG. 2, the sensor receptacle 30 is configured as a pocket-shaped receptacle into which the sensor 32 can be inserted completely or at least almost completely. In the herein shown embodiment, the pocket-shaped sensor receptacle 30 surrounds the sensor 32 from five spatial sides. However, one of the six spatial sides is open in order to be able to remove the sensor 32 from the sensor receptacle 30, as schematically indicated in FIG. 2.

[0080] The sensor receptacle 30 is arranged on the tool holder 10 in such a way that, in the mounted state of the tool holder, the sensor inserted into the sensor receptacle 30 does not come into direct contact either with the tool 12 mounted on the tool holder 10 or with the machine tool to which the tool holder 10 is fastened. In other words, the sensor receptacle 30 is spaced from both the tool receptacle 14 and the machine interface 26.

[0081] The sensor 32 is preferably a force transducer. This force transducer is configured to measure the forces acting on the tool holder 10 resulting from the machining forces acting on the tool 12. In other words, the sensor 32 is used to measure the cutting or machining forces acting on the at least one cutting edge 22 during use of the tool 12. At least, the measurement signal generated by the sensor 32 is dependent on a force acting on the at least one cutting edge 22.

[0082] The sensor 32 is inclined in the tool holder 10. More specifically, a sensitive axis of the sensor 32, shown in FIG. 3 with a dashed line and indicated with reference numeral 34, is inclined with respect to the longitudinal direction or longitudinal axis 36 of the tool holder 10. The sensitive axis 34 is an axis along which the sensor 32 has its main sensitivity. This axis 34 is preferably perpendicular to a top or bottom surface 38 of the sensor 32.

[0083] The angle α, at which the sensitive axis 34 of the sensor 32 is inclined relative to the longitudinal axis 36 of the tool holder 10, preferably has a magnitude of 30°-60°. Thus, the angle α is preferably an acute angle.

[0084] The angle α is particularly preferably selected in such a way that the sensitive axis 34 of the sensor 32 coincides with the direction of a resultant force acting on the tool holder 10 during the machining process or is oriented at an angle of at most 10° relative to this direction. In particular, this is the direction of the resultant force at the location of the sensor 32. The direction of this resultant force is schematically indicated in FIG. 4 by means of an arrow with the reference numeral 40 or 40′.

[0085] During machining, a force acts on the cutting insert 20 or the cutting edge 22, which is schematically indicated with the arrow 68 in FIG. 4. This machining force 68 can be divided into a cutting force component 70 and a feed force component 72. In a three-dimensional view, the portion of the passive force perpendicular to it would also have to be considered, but this is omitted here for the sake of simplicity.

[0086] Due to the machining force 68, corresponding forces and moments are induced in the tool holder 10, whose amounts and directions differ from each other depending on the observation location in the tool holder 10. FIG. 4 shows schematically the force parallelograms for two possible positions 74, 74′, with the resulting forces 40, 40′ acting at these positions 74, 74′ respectively.

[0087] The resulting forces 40, 40′ each include a vertical force component 48, 48′ and a horizontal force component 50, 50′. The vertical force components 48, 48′ each result essentially from the cutting force component 70 of the machining force 68. The horizontal force components 50, 50′, on the other hand, result essentially from the feed force component 72 of the machining force 68 and from the moment-induced lever force at the respective position 74, 74′ of the sensor 32. The associated lever arms are the vertical and horizontal distances of the positions 74, 74′ from the cutting edge 22.

[0088] Hence, a tensile load results for position 74, whereas a compressive load results for position 74′. Thus, if the sensor 32 is arranged at the first position 74 in the tool holder 10, it is essentially subjected to a tensile load. On the other hand, if the sensor 32 is arranged at the second position 74′ in the tool holder 10, it is essentially subjected to a compressive load. Depending on the location, the alignment of the sensitive axis 34 of the sensor 32 is carried out as precisely as possible along the direction of the resulting force 40 or 40′.

[0089] It goes without saying that the positions 74, 74′ shown are possible positions of the sensor 32 in the force shunt. When the sensor 32 is arranged in the force shunt, only a part of the forces flows through the sensor 32. Therefore, the parallelograms schematically shown in FIG. 4 also represent only a part of the forces in the cutting plane of the tool holder 10, namely the part that flows through the sensor 32 at the respective position 74, 74′.

[0090] As can further be seen from FIG. 4, the tool 12 rests against two abutment surfaces 42, 44 in the tool receptacle 14 when the tool 12 is mounted on the tool holder 10. In the herein shown embodiment, the first abutment surface 42 extends in a vertical direction, while the second abutment surface 44 extends horizontally. Accordingly, the two abutment surfaces 42, 44 extend perpendicularly to each other. As can be seen in FIG. 4, the second abutment surface 44 is interrupted by a recess 46 in order to stabilize the support of the tool 12 or to be able to design it even more precisely.

[0091] Thus, depending on whether mainly tensile or compressive loads are to be measured with the sensor 32, two possible optimal positions (see positions 74, 74′) or alignments of the sensor 32 within the tool holder 10 result. One of the two optimal alignment possibilities is shown in FIG. 3, in which the sensitive axis 34 of the sensor 32 coincides with the direction 40 of the resulting force. The second optimal alignment possibility, which is not explicitly shown here, is the alignment of the sensitive axis 34 of the sensor 32 along the direction 40′ (cf. FIG. 4).

[0092] The more precisely the sensitive axis 34 is aligned with the direction 40 of the resulting force, the more accurate and stable measurements of the cutting forces acting on the at least one cutting edge 22 are possible. Since the second abutment surface 44 is in the present embodiment oriented parallel to the longitudinal axis 36 of the tool holder 10, the same angle α thus results not only between the sensitive axis 34 and the longitudinal axis 36, but also between the sensitive axis 34 and the second abutment surface. A corresponding opposite angle results between the sensitive axis 34 and the first abutment surface 42.

[0093] The sensor 32 is clamped in the tool holder 10 by means of a clamping device 52, which is shown in detail in FIG. 5. More precisely, the sensor 32 is clamped by means of this clamping device 52. The clamping device 52 comprises two wedge elements 54, 56. These two wedge elements 54, 56 are inserted into the sensor receptacle 30 in opposite directions to each other. The first wedge element 54 rests with its first side surface 58 against the sensor 32 and with its opposite second side surface 60 against a wedge surface 62 of the second wedge element 56. The first side surface 58 is preferably oriented parallel to the top surface of the sensor 32 against which it abuts. The second side surface 60 and the wedge surface 62 are preferably flush against each other and oriented at an acute angle relative to the first side surface 58 that abuts the sensor 32. The second wedge element 56 can preferably be displaced by means of two screws (not shown) (cf. FIGS. 1 and 2). In this way, the preload force with which the sensor 32 is preloaded in the sensor receptacle 30 can be precisely adjusted.

[0094] The first wedge element 54 rests on its end face against an abutment surface 59 provided inside the sensor receptacle 30. This abutment surface 59 serves as a support for the first wedge element 54. It supports the first wedge element 54 in particular during the insertion of the second wedge element 56 into the sensor receptacle 30 and thereby prevents a transmission of undesired shear forces from the first wedge element 54 to the sensor 32. Thus, the provided clamping device 52 enables the sensor 32 to be clamped within the sensor receptacle 30 without the sensor 32 experiencing undesired shear forces as a result.

[0095] It goes without saying that this type of supporting the first wedge element 54 may be accomplished in another manner without departing from the spirit and scope of the present disclosure.

[0096] However, a preload of the sensor 32 along its sensitive axis 34 is preferred. Such a preload is particularly necessary if not only compressive but also tensile loads are to be measured by means of the sensor 32. In case of a tensile load, the preload of the sensor 32 must be greater than the tensile force acting on the sensor 32 as a result of the machining process so that the sensor 32 always remains in a preloaded state.

[0097] The sensor 32 is connected via a cable 64, which is routed out of the sensor receptacle 30 to the outside through a cable duct 66 running inside the tool holder 10 (cf. FIG. 2). The cable 64 is thus safely protected from damage and connecting the sensor 32 can be done without any problems.

[0098] FIGS. 6-8 show a second embodiment of the tool system 100′. Identical or equivalent components are provided therein with the aforementioned reference signs including an additional apostrophe.

[0099] The tool system 100′ shown in FIGS. 6-8 is a cutting tool with an elongated tool holder 10′, at the front end 76 of which a pot-shaped tool receptacle 14′ is arranged. The tool 12′ is in this case a cutting insert 20′ which is releasably fastened in the tool receptacle 14′ by means of a fastening means 78. In this case, the fastening means 78 is configured as a clamping screw. However, it goes without saying that other possibilities for fastening the tool 12′ in the tool receptacle 14′ are also possible without leaving the spirit and scope of the present disclosure.

[0100] Here, the rear portion of a tool holder shank 80 serves as the machine interface 26′. This tool holder shank 80 may be partially flattened at one or more locations to facilitate attachment of the tool holder 10′ to a machine tool.

[0101] The cutting insert 20′ comprises a clamping section 82, a cantilever arm 84, and a cutting head 86 on which the at least one cutting edge 22′ is arranged. The cutting head 86 is arranged at the first end of the cantilever arm 84. The clamping section 82 is arranged at the opposite second end of the cantilever arm 84. The cantilever arm 84 has a smaller cross-section than the clamping section 82.

[0102] In the assembled state, the clamping section 82 of the tool 12′ is inserted into the tool receptacle 14′. In this embodiment, the clamping section 82 and the tool receptacle 14′ have a substantially teardrop-shaped cross-section.

[0103] In this embodiment, the sensor 32′ is also removably inserted into a sensor receptacle 30′ that is spaced from both the tool receptacle 14′ and the machine interface 26′. Similarly, the position and orientation of the sensor 32′ is also in this case selected such that the sensor 32′ is exposed to the lowest possible shear forces and is positioned as parallel as possible to the force flow within the tool holder 10′. However, due to the slightly different force flow within the tool holder 10′, the sensitive axis 34′ is in this case aligned parallel or at least substantially parallel to the longitudinal axis 36′ of the tool holder 10′ (cf. FIG. 8).

[0104] In this case, the clamping device 52′ comprises a fastening screw 88 by means of which the sensor 32′ can be axially preloaded. In addition, a plate-shaped pressure piece 90 serves to distribute the force as evenly as possible and over the entire surface of the sensor 32′ and to avoid undesirable shear forces. The plate-shaped pressure piece 90 is arranged between the sensor 32′ and the fastening screw 88 and preferably lies flat against the sensor 32′. The mode of operation of the sensor 32′ otherwise corresponds essentially to the mode of operation as explained with respect to the first embodiment.

[0105] It is to be understood that the foregoing is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

[0106] As used in this specification and claims, the terms “for example,” “e.g.,” “for instance,” “such as,” and “like,” and the verbs “comprising,” “having,” “including,” and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.