APPARATUS AND METHOD FOR CUTTING EDGE PREPARATION
20220305605 · 2022-09-29
Inventors
Cpc classification
B24D5/063
PERFORMING OPERATIONS; TRANSPORTING
B24B27/0076
PERFORMING OPERATIONS; TRANSPORTING
International classification
B24B27/00
PERFORMING OPERATIONS; TRANSPORTING
Abstract
The invention describes an apparatus (1) for a cutting edge preparation of cutting tools (5), in particular of drills or milling tools or similar tools (5), in particular of hard-metal cutting tools, wherein during a relative movement the cutting tool (5) interacts in a machining fashion with a flexibly-bonded grinding body (2) that is provided with abrasive particles, the particles of the grinding body (2) influencing the edge geometry of the cutting tool (5),
wherein the grinding body (2) is adapted with its dimensions substantially to the dimensions of the respective cutting tool (5) that is to be prepared and is accommodated in an exchangeable holder (4) which is arranged in a region of a processing device, in particular of a tool grinding machine, and is held such that it is machinable by the cutting tool (5) for the cutting edge preparation. Furthermore, a corresponding method and a corresponding grinding body (2) are given.
Claims
1. An apparatus (1) fora cutting edge preparation of cutting tools (5), wherein during a relative movement the cutting tool (5) interacts in a machining fashion with a flexibly-bonded grinding body (2) that is provided with abrasive particles, the particles of the grinding body (2) influencing the edge geometry of the cutting tool (5), wherein the grinding body (2) is adapted with its dimensions substantially to the dimensions of the respective cutting tool (5) that is to be prepared and is accommodated in an exchangeable holder (4) which is arranged in a region of a processing device and is held such that it is machinable by the cutting tool (5) for the cutting edge preparation.
2. The apparatus (1) according to claim 1, wherein the exchangeable holder (4) is held in the workroom of a tool grinding machine.
3. The apparatus (1) according to claim 1, wherein the grinding body (2) is implemented substantially in a cylindrical fashion.
4. The apparatus (1) according to claim 3, wherein the cylindrical circumferential measurements of the grinding body (2) are substantially adapted to the circumferential measurements of the cutting tool (5) that is to be prepared.
5. The apparatus (1) according claim 1, wherein after complete usage, the grinding body (2) can be simply replaced by a new grinding body (2).
6. The apparatus (1) according to claim 1, whrerein the rotationally symmetrical grinding body (2) can be manufactured and be pressed into the exchangeable holder (4) with a very slight allowance that is adapted to the diameter of the cutting tool (5) that is to be prepared.
7. The apparatus (1) according to claim 1, wherein the exchangeable holder (4) is insertable into a bore (11) in the grinding disk receptacle (3).
8. The apparatus (1) according to claim 7, wherein the exchangeable holder (4) comprises an outer thread (6), which can be screwed into the bore (11) in the grinding disk receptacle (3) that is provided with an inner thread, or of a different processing device.
9. The apparatus (1) according to claim 7, wherein that the exchangeable holder (4) can be pressed or inserted into the bore (11) in the grinding disk receptacle (3) and is held there in a rotationally fix fashion.
10. The apparatus (1) according to claim 1, wherein a guide bushing (12) is arranged in the region of the exchangeable holder (4) for the grinding body (2), via which long-projecting asymmetrical cutting tools (13), having a great length:diameter ratio, can be guided and prepared, wherein the guide bushing (12) is arranged relative to the exchangeable holder (4) in such a way that the guide bushing (12) guides and supports the long-projecting cutting tool (13) in front of the region of the machining of the grinding body (2).
11. The apparatus (1) according to claim 1, wherein sensor elements, which provide information on the progression of the cutting edge preparation, are introducible in the exchangeable holder (4), wherein the sensor elements are equipped with accumulators, which are integrated in the exchangeable holder (4) and can be charged in the grinding disk magazine or externally while not in use.
12. The apparatus (1) according to claim 1, wherein the grinding body (2) comprises abrasive particles and is successively completely machinable by the cutting tools (5) which are to be prepared.
13. The apparatus (1) according to claim 12, wherein the grinding body (2) comprises a mixture of fine and coarse abrasive particles, wherein a distribution of fine and coarse abrasive particles within the grinding body (2) is implemented inhomogeneously.
14. The apparatus (1) according to claim 1, wherein the grinding body (2) has an axially-extending perforation (15) which is adapted to the cutting tool diameter (5) and within which the cutting tool (5) is not affected by the particles of the grinding body (2).
15. The apparatus (1) according to claim 1, wherein the grinding body (2) comprises sections (21, 22) having differing degrees of hardness of the bonding.
16. A method for a cutting edge preparation of cutting tools (5), wherein during a relative movement the cutting tool (5) interacts in a machining fashion with a flexibly-bonded grinding body (2) which is provided with abrasive particles, the particles of the grinding body (2) influencing the edge geometry of the cutting tool (5), wherein the grinding body (2) is adapted with its dimensions substantially to the dimensions of the respective cutting tool (5) that is to be prepared and is accommodated in an exchangeable holder (4) which is arranged in the region of a processing device and in which the grinding body (2) is successively completely machined by the cutting tools (5) which are to be prepared.
17. The method according to claim 16, wherein the cutting edge preparation is carried out in the same clamping arrangement, directly following a first-time manufacturing of the shape of the cutting tool (5) or following a regrinding of the cutting tool (5), on the same processing device.
18. The method according to one of claim 16, wherein in the machining of the grinding body a wide range of adaptation of the cutting speeds is obtainable by the relative movement of grinding body (2) and cutting tool (5).
19. The method according to claim 18, wherein the grinding body (2) and the cutting tool (5) execute rotary movements during the machining of the grinding body (2), wherein a superimposition of the rotary movements of the grinding body (2) and of the cutting tool (5) permits selective roundings of the cutting edge of the cutting tool (5).
20. The method according to claim 18, wherein during the cutting edge preparation the cutting tool (5) that is to be prepared executes the necessary translational and rotary movements.
21. The method according to claim 16, wherein the grinding body (2) creates variable roundings over the cutting region of the cutting tools (5) by means of sections having different degrees of hardness of the bonding.
22. The method according to claim 16, wherein due to an axially-extending perforation (15), which is adapted to the cutting tool diameter (5) and within which the cutting tool (5) is not affected by the particles of the grinding body (2), the grinding body (2) does not subject the axial regions of the cutting tool (5) to a cutting edge preparation.
23. The method according to claim 16, wherein the grinding body (2) has external measurements which are adapted to the cutting tool diameter (5), such that only selected regions of the cutters of the cutting tool (5) are subjected to a cutting edge preparation.
24. The method according to claim 16, wherein the cutting edge preparation is carried out on new tools (5) or on cutting tools (5) which were reground and are therefore already coated with a hard-metal layer on certain functional surfaces.
25. The method according to claim 16, wherein the cutting tool (5) having main cutters and secondary cutters successively machines—by means of its main cutters, respectively secondary cutters—respectively corresponding grinding bodies (2) which have different characteristics and are allocated one by one.
26. A grinding body (2) for an execution of the method according to claim 16, wherein the cylindrical circumferential measurements of the grinding body (2) are substantially adapted to the circumferential measurements of the cutting tool (5) that is to be prepared.
Description
[0035] A particularly preferred embodiment of the apparatus according to the invention is shown in the drawing.
[0036] It is shown in
[0037]
[0038]
[0039]
[0040]
[0041]
[0042] In
[0043] On the cone-shaped receptacle 10 in the workroom of the tool grinding machine, a receiving collar 3 is arranged for receiving the grinding disk 14, on which the grinding disk 14 is plugged with its perforation and is then secured in a customary manner by a cap nut 9 via a thread 8. This receiving collar 3 is usually made of a full material and has no further task besides supporting the grinding disk 14.
[0044] According to the invention, a portion of the receiving collar 3 which is otherwise made of a full material and which is situated centrally in the work region of the tool grinding machine, is used for an accommodation of the apparatus 1 according to the invention. For this purpose, from the work region of the tool grinding machine a central longitudinal bore 11 is introduced into the receiving collar 3 as a blind bore, which a sleeve-like, easily exchangeable holder 4 for a grinding body 2—that will be described in detail below—can be inserted in. As a result of this arrangement of the apparatus 1, the apparatus 1 will not encumber normal operation of the tool grinding machine while providing the receptacle for a grinding body 2, which may be used for the cutting edge preparation of a cutting tool 5.
[0045] The exchangeable holder 4 has such an outer diameter that it is insertable into the longitudinal bore 11 of the receiving collar 3 in a largely tolerance-free manner. A fixing of the exchangeable holder 4 in the longitudinal bore 11 can be brought about by an end-side thread 6 on the outer surface of the exchangeable holder 4, which can be screwed into a corresponding counter-thread in the longitudinal bore 11. It would also be conceivable to fix the exchangeable holder 4 in the longitudinal bore 11 by pressing-in or in another form-fit or force-fit manner if, on the one hand, a rotationally fix fixation is ensured with easy exchangeability of the exchangeable holder 4.
[0046] In the interior of the sleeve-like structured exchangeable holder 4 there is also a bore 23 that a cylindrical grinding body 2, which may be used for an interaction with the cutters 7 of the cutting tool 5 in the context of the cutting edge preparation of the cutting tool 5, can be inserted into or pressed into in a rotationally fix fashion. The grinding body 2 is implemented of a flexibly bonded abrasive-particle matrix, for example of rubber-like bonded abrasive particles which are made of hard materials.
[0047] In regard to its cylindrical outer measurements, the grinding body 2 is adapted to the circumferential measurements of the cutting tool 5, in the present case the outer diameter of the drill, and has an outer diameter that is slightly greater than the outer diameter of the cutting tool 5, such that in the cutting edge preparation the cutters of the cutting tool 5 in any case come into contact only with the grinding body and not with the exchangeable holder 4.
[0048] In order to carry out the cutting edge preparation of the cutting tool 5, for example after basic grinding of the tool shape by means of the grinding disk 14, the cutting tool 5 that is embodied as a drill is positioned, in the longitudinal bore 11 of the receiving collar 3, in front of the apparatus 1 in such a way that the axis of the cutting tool 5 and the longitudinal bore 11, and thus the exchangeable holder 4, are in alignment with one another. The cutting tool 5 is then—during a relative rotation between the cutting tool 5 and the grinding body 2—advanced to the grinding body 2 in the feed direction until the cutters of the cutting tool 5 interact in the designated manner with the grinding body 2, machining the grinding body 2 and being thus prepared. Herein the grinding body 2 is machined at least section-wise and is thus shortened in a longitudinal direction. Following the cutting edge preparation of the cutting tool 5, the cutting tool 5 is re-traversed out of the exchangeable holder 4 against the feed direction 24 and is ready for removal.
[0049] The process may then be repeated with the subsequent cutting tool 5, as a result of which the grinding body 2 is more and more machined away successively and, upon reaching a use-up limit, must be replaced. For this purpose, the entire exchangeable holder 4 containing the remainder of the grinding body 2 is removed out of the longitudinal bore 11 and is replaced by a exchangeable holder 4 that has been pre-equipped with a new grinding body 2. Due to the quick exchangeability of the exchangeable holder 4 containing the grinding body 2, work can be continued directly. Further exchangeable holders 4 of the same type may, for example, be stored in other grinding disk receptacles as a depot, to be used if the preparation remains the same. This allows delaying the replacement of the grinding body 2 until the job has been finished or until the wear limits of the grinding disks 14 have been reached.
[0050] In
[0051]
[0052] In
[0053]
[0054] It is also conceivable, as shown in
[0055] In
[0056] For example, the reamer 18 shown in
[0057] In
[0058]
[0059]
[0060] In the following essential characteristics and advantages of the invention will be briefly explained:
[0061] The basic idea of the method according to the invention is the usage of a flexibly-bonded grinding body 2 implemented of abrasive particles, which is here exemplarily installed in a specifically developed grinding disk receptacle 3. In the defined machining of such a grinding body 2, material abrasion will occur on the cutting edge of the cutting tool 5, which may be used for a selective preparation. This method is carried out, for example, on a customary tool grinding machine and can thus be integrated at the end of the process chain for tool production, respectively for tool regrinding, without additional handling efforts. The material abrasion that is necessary for the preparation is generated by the relative movement between a grinding body 2 and a cutting tool 5. The cylindrical grinding body 2 is herein, for example, clamped in the grinding disk receptacle 3 in a positionally fixed manner while the necessary translational and rotary movements are executed by the cutting tool 5 that is to be prepared.
[0062] Furthermore, due to deliberate superimposition of the rotational directions of the cutting tool 5 and the grinding disk receptacle 3, there is in this case a possibility of selectively adjusting roundings and tiltings of the cutting edge. It is further possible, due to a construction of the grinding body 2 with different degrees of hardness, to create variable roundings over the cutter region of the cutting tool 5. A well-known problem is the rounding of the transverse cutter of the cutting tool 5 brought about by established preparation methods. The usage of a grinding body 2 having a perforation 15 that is adapted to the tool diameter 5 provides possibilities of adapting the main cutters, for example of a drilling tool 5, to the preparation process while avoiding a rounding of the transverse cutter. The same applies in regard to the accurate adaptation of the diameter of the grinding body 2 to the diameter of the cutting tool 5 that is to be prepared.
[0063] Beyond this, due to the free process cinematic, there are further fields of application, like for example the preparation of reamers, micro-milling tools and sequential drilling tools.
[0064] The machining of the grinding body 2 results in a material abrasion on the cutting edge of the cutting tool 5, which is thus rounded. The advantage of the method according to the invention lies in that the tool production (grinding of the macro-shape) and a defined generation of the microscopic cutting edge shape can be carried out, for example, on the same tool grinding machine or processing device. Due to the machining of the grinding body 2, new abrasive medium will always be available, as a result of which there are constant preparation conditions for the duration of the process. Influencing of the tools is herein limited to those regions of the cutting tool 5 that come into contact with the grinding body 2, which constitutes an advantage with respect to other preparation methods, like drag grinding or abrasive blasting. In addition to the low investment costs, preparation costs per tool are small as the exchange of grinding bodies 2 can be brought about in a quick and simple manner.
[0065] With the current state of the art, in particular the cutting edge rounding of long-projecting cutting tools 13 having a high length:diameter ratio (l/d ratio) requires special handling and extensive process controlling if a suitable cutting edge preparation is to be realized. The apparatus according to the invention offers the potential of enabling a preparation of such long-projecting cutting tools 13 by the simple cinematic and by processing in one clamping arrangement and within existing production procedures on the tool grinding machine or processing device in a short time. However, besides cutting tools 13 having a high l/d ratio customary rotationally symmetrical machining tools may also be prepared by the present method with a slight modification of the grinding bodies 2.
[0066] In addition to the cutting edge rounding of new tools 5, the method according to the invention also enables a preparation of cutting tools 5 which were reground and are therefore already coated with a hard-material layer on certain functional surfaces. According to currently available knowledge, this cannot be selectively realized by currently available methods, such that the performance of reground cutting tools 5 is mostly significantly lower than the performance of new cutting tools 5.
[0067] For the implementation of the apparatus 1 according to the invention, the accommodation of the exchangeable holder 4, for example in the grinding disk receptacle 3, is crucial. The grinding disk receptacles 3 normally used on tool grinding machines have corresponding interfaces to the tool grinding machine spindle. These are usually embodied as hollow-shaft cones (HSK), shaft cones (SK) or as a further, mostly standardized, interface in order to permit high flexibility and precision with the grinding disk exchange. Herein for a tool grinding, the grinding disks are usually put upon a mandrel 3, having for example a diameter d=20 mm, they are positioned by means of distance rings and are fixed via a clamping nut 9. The core of the mandrel 3 has not had any function up to now. Fitting-in the exchangeable holder 4, in the present case into a bore 11 having an inner thread, provides the mandrel 3 with an additional functionality and the grinding disk receptacle 3 is considerably upgraded in regard to its utilizability. Besides the fixation of the exchangeable holder 4 the connection, which can be screwed or can be joined otherwise, might also permit an implementation of further functional elements which are not involved in the cutting edge preparation. Moreover, corresponding receptacles could be provided on other processing devices, for example on turning machines, drilling machines, or other specifically or universally applicable devices.
[0068] The grinding bodies 2 developed specifically for the application in the cutting edge preparation have an elastic bonding of the abrasive particles with a degree of hardness that must be defined depending on the respective application case. This is a rotationally symmetrical grinding body 2 containing fine or coarse abrasive particles, for example silicon carbide, aluminum dioxide or diamond, which is successively completely machined by the cutting tools 5 which are to be prepared. The rotationally symmetrical grinding bodies 2 are herein adapted to the diameter of the cutting tool 5 that is to be prepared; they are produced with a very small allowance and are pressed into the exchangeable holder 4. In this way rounding of the exposed cutter corners of the cutting tools 5 can be avoided or can be significantly minimized in comparison to existing methods. It is possible, besides the rotationally symmetrical base bodies having a defined bonding hardness, to produce grinding bodies 2 which have different degrees of hardness and are thus correspondingly adapted to the application case and to the diameters that are to be processed. In this context in particular the possibility may be mentioned that with the cutting tools 5 it may be necessary that the core 16 of the grinding body 2 has a higher hardness than the peripheral region 17 in order to obtain a regular cutting edge rounding due to the elastic deformation of the rotationally symmetrical grinding body 2.
[0069] Furthermore, the process cinematic offers additional possibilities of covering a wide range of parameters in regard to the cutting speeds when machining the grinding body 2, for example by the superimposition of the rotation directions and rotation speeds, independently from the performance capability of the workpiece spindle and of the tool spindle. Moreover, by differently oriented, counter-directional and co-directional movements of the grinding disk receptacle 3 with the integrated grinding body 2 and the cutting tool 5, influences regarding the cutting edge tilting, of form factor K, may be enabled and adjusted. By way of the introduction of perforations 15, the introduction of cores 16 having different hardnesses, abrasive particles and grain sizes, and the flexible shaping of the grinding bodies 2, this method provides an opportunity of a transfer to a great number of further variants of machining tools 5. Beyond this, superimposition of the axes of the grinding disk receptacle 3 allows developing and realizing a different cinematic which approximates a milling processing, thus enabling a preparation of different milling tools selectively in regard to front cutters and/or circumferential cutters.
[0070] In addition to the afore-described usage for grinding bodies 2 for a cutting edge preparation, the apparatus 1 may also be extended by making use of measuring technology or of sensorics. Introducing electrical conductor paths and sensors into the exchangeable holder 4 even permits an implementation of an electronical, accumulator-equipped surveillance electronics arrangement, which may be charged with a suitable charging technology in the grinding disk magazine or externally while not in use.
[0071] Due to the integration of the apparatus 1 in the grinding disk receptacle 3, only insignificantly higher acquisition costs will be incurred in comparison to customary grinding disk receptacles 3. This also means that due to the integration in the grinding disk receptacle 3, the concept is applicable on almost any tool grinding machine or processing machine. Therefore the investment—necessary for most of already known methods—for additional installations including the thus arising maintenance and repair costs, as well as for the handling of the workpiece after the grinding process. While the complete processing, for example on the tool grinding machine, causes times when the machine cannot be used for its primary purpose, such times are negligible due to the very short processing periods of less than 5 s for each preparation. Changing of tools is avoidable by an intelligent composition of grinding disk packages on the grinding mandrel and/or by furnishing each grinding disk receptacle 3 with the apparatus 1 according to the invention, resulting in an overall increase in productivity and in a considerable reduction of production costs.
[0072] The adaptation of the grinding bodies 2 to the diameter of the cutting tools 5 and the pre-defined maximum allowance of the grinding body 2 that is to be machined ensure a nearly non-relevant influencing of the cutter corners and of the secondary cutters of the cutting tools 5. Moreover, as the contact area between the cutting tool 5 and the grinding body 2 that is to be machined is limited by the machining thickness, there will be no influencing of the peripheral surfaces of the cutting tool 5. The defined length of the rotationally symmetrical grinding body 2 within the exchangeable holder 4 allows processing a number of cutting tools 5 that depends on a diameter and on a target rounding by using the proposed concept until the grinding body 2 that is to be machined is used up completely. Exchanging the exchangeable holder 4, respectively changing to a further grinding disk receptacle 3 comprising an identical grinding body 2, allows continuous processing close to the process chain. The free cinematic provided by the mounting in the grinding disk receptacle 3 also offers the potential of realizing a different process cinematic, similar to milling, on the tool grinding machine. Thus opportunities arise of preparing main cutters and secondary cutters of the cutting tools 5 with different cutting edge roundings and form factors.
[0073] In addition to the variation of the shape of the grinding bodies 2 and of the bonding hardness, it is possible to create different shapes of cutting edge rounding via an adaptation of the cinematic engagement conditions. Herein the rotation direction of the cutting tool 5, the rotation direction of the grinding body 2, the dwell time at the bottom of the bore and the advancement per turn are of particular relevance.
[0074] For long-projecting deep-drilling tools 13 having different diameters a guiding of the tool tip is necessary for enabling cutting edge preparation without getting the cutting tool 5 damaged. For this an adaptation of the exchangeable holder 4 is necessary. The guiding of the cutting tool 5 must be dimensioned such that the grinding body 2 coincides with the workpiece axis and the elastic bending of the cutting tool 5 is compensated. Herein the complexity of the preparation results from the requirements regarding the cutting edge. In the case of an application with deep-hole drilling tools, besides the more extensive rounding of the outer cutter, a significantly smaller rounding of the inner cutter must be achieved.
LIST OF REFERENCE NUMERALS
[0075] 1 apparatus according to the invention [0076] 2 grinding body [0077] 3 receiving collar/grind disk receptacle [0078] 4 exchangeable holder [0079] 5 cutting tool [0080] 6 thread of exchangeable holder [0081] 7 cutters of cutting tool [0082] 8 clamping thread [0083] 9 clamping nut [0084] 10 tool cone [0085] 11 bore in grinding disk receptacle [0086] 12 guide bushing [0087] 13 deep hole drill [0088] 14 grinding disk [0089] 15 perforation [0090] 16 core having higher bonding hardness [0091] 17 circumferential region having lower [0092] bonding hardness [0093] 18 frictional tool [0094] 19 sequential drill [0095] 20 milling tool [0096] 21 surrounding grinding body [0097] 22 inside-situated grinding body [0098] 23 bore holder [0099] 24 feed direction [0100] 25 pallet-like magazine [0101] 26 receptacles