Method for Producing a Green Body and Method for Further Processing the Green Body Into a Machining Segment for the Dry Machining of Concrete Materials

Abstract

A method for producing a green body for a machining segment, where the machining segment is connectable to a basic body of a machining tool by an underside of the machining segment, includes placing first hard material particles in a matrix material in a defined particle pattern. The first hard material particles are placed in the matrix material with a respective projection with respect to the matrix material.

Claims

1.-10. (canceled)

11. A method for producing a green body for a machining segment, wherein the machining segment is connectable to a basic body of a machining tool by an underside of the machining segment, comprising the step of: placing first hard material particles in a matrix material in a defined particle pattern; wherein the first hard material particles are placed in the matrix material with a respective projection with respect to the matrix material.

12. The method as claimed in claim 11, wherein the projection is at least 400 μm with respect to the matrix material.

13. The method as claimed in claim 11 further comprising the step of encasing the first hard material particles with a casing material that comprises the matrix material.

14. The method as claimed in claim 11 further comprising the step of encasing the first hard material particles by a casing material that is different from the matrix material.

15. The method as claimed in claim 11 further comprising the step of admixing second hard material particles with the matrix material, wherein an average particle diameter of the second hard material particles is less than an average particle diameter of the first hard material particles.

16. A method for processing the green body produced by the method as claimed in claim 11, comprising the steps of: compacting the green body by pressure between a first press punch and a second press punch to form a compact body; and processing the compact body to produce the machining segment.

17. The method as claimed in claim 16, wherein the second press punch has depressions in a pressing surface and wherein an arrangement of the depressions corresponds to the defined particle pattern of the first hard material particles.

18. The method as claimed in claim 16, wherein the step of compacting includes hot-pressing.

19. The method as claimed in claim 18, wherein the second press punch has depressions in a pressing surface and wherein an arrangement of the depressions corresponds to the defined particle pattern of the first hard material particles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIGS. 1A, 1B show two variants of a machining tool taking the form of a core drill bit;

[0019] FIGS. 2A, 2B show two variants of a machining tool taking the form of a saw blade;

[0020] FIG. 3 shows a machining tool taking the form of an abrasive disk;

[0021] FIG. 4 shows a machining tool taking the form of a cut-off grinding chain;

[0022] FIGS. 5A-C show a machining segment in a three-dimensional representation (FIG. 5A), in a view of an upper side (FIG. 5B), and in a view of a side surface (FIG. 5C);

[0023] FIGS. 6A, 6B show the production of the machining segment of FIGS. 5A-C from a green body (FIG. 6A), which is compressed in one embodiment to form a compact body (FIG. 6B); and

[0024] FIGS. 7A-C show some tool components that are used during the further processing of the green body of FIG. 6A to form the machining segment of FIGS. 5A-C.

DETAILED DESCRIPTION OF THE DRAWINGS

[0025] FIGS. 1A, 1B show two variants of a machining tool taking the form of a core drill bit 10A, 10B. The core drill bit 10A shown in FIG. 1A is referred to below as the first core drill bit, and the core drill bit 10B shown in FIG. 1B is referred to as the second core drill bit; in addition, the first and second core drill bits 10A, 10B are both included under the term “core drill bit”.

[0026] The first core drill bit 10A comprises a number of machining segments 11A, a tubular basic body 12A and a tool fitting 13A. The machining segments 11A, which are used for core drilling, are also referred to as drilling segments and the tubular basic body 12A is also referred to as a drilling shaft. The drilling segments 11A are fixedly connected to the drilling shaft 12A, for example by screwing, adhesive bonding, brazing or welding.

[0027] The second core drill bit 10B comprises an annular machining segment 11B, a tubular basic body 12B and a tool fitting 13B. The annular machining segment 11B, which is used for core drilling, is also referred to as a drilling ring, and the tubular basic body 12B is also referred to as a drilling shaft. The drilling ring 11B is fixedly connected to the drilling shaft 12B, for example by screwing, adhesive bonding, brazing or welding.

[0028] The core drill bit 10A, 10B is connected via the tool fitting 13A, 13B to a core drill and, in drilling operation, is driven by the core drill in a direction of rotation 14 about an axis of rotation 15. During the rotation of the core drill bit 10A, 10B about the axis of rotation 15, the core drill bit 10A, 10B is moved along a feed direction 16 into a workpiece to be machined, with the feed direction 16 running parallel to the axis of rotation 15. The core drill bit 10A, 10B creates a drill core and a borehole in the workpiece to be machined.

[0029] The drilling shaft 12A, 12B in the exemplary embodiment of FIGS. 1A, 1B is formed in one piece and the drilling segments 11A and the drilling ring 11B are fixedly connected to the drilling shaft 12A, 12B. Alternatively, the drilling shaft 12A, 12B may be of a two-piece form, composed of a first drilling shaft section and a second drilling shaft section, with the drilling segments 11A or the drilling ring 11B being fixedly connected to the first drilling shaft section, and the tool fitting 13A, 13B being fixedly connected to the second drilling shaft section. The first and second drilling shaft sections are connected to one another via a releasable connection device. The releasable connection device takes the form for example of a plug-and-twist connection as described in EP 2 745 965 A1 or EP 2 745 966 A1. The formation of the drilling shaft as a one-piece or two-piece drilling shaft has no influence on the structure of the drilling segments 11A or of the drilling ring 11B.

[0030] FIGS. 2A, 2B show two variants of a machining tool taking the form of a saw blade 20A, 20B. The saw blade 20A shown in FIG. 2A is referred to below as the first saw blade and the saw blade 20B shown in FIG. 2B is referred to as the second saw blade; in addition, the first and second saw blades 20A, 20B are both included under the term “saw blade”.

[0031] The first saw blade 20A comprises a number of machining segments 21A, a disk-shaped basic body 22A and a tool fitting. The machining segments 21A, which are used for sawing, are also referred to as sawing segments, and the disk-shaped basic body 22A is also referred to as a blade body. The sawing segments 21A are fixedly connected to the blade body 22A, for example by screwing, adhesive bonding, brazing or welding.

[0032] The second saw blade 20B comprises a number of machining segments 21B, an annular basic body 22B and a tool fitting. The machining segments 21B, which are used for sawing, are also referred to as sawing segments, and the annular basic body 22B is also referred to as a ring. The sawing segments 21B are fixedly connected to the ring 22B, for example by screwing, adhesive bonding, brazing or welding.

[0033] The saw blade 20A, 20B is connected to a saw via the tool fitting and, in sawing operation, is driven by the saw in a direction of rotation 24 about an axis of rotation 25. During the rotation of the saw blade 20A, 20B about the axis of rotation 25, the saw blade 20A, 20B is moved along a feed direction, the feed direction running parallel to the longitudinal plane of the saw blade 20A, 20B. The saw blade 20A, 20B creates a sawing slit in the workpiece to be machined.

[0034] FIG. 3 shows a machining tool taking the form of an abrasive disk 30. The abrasive disk 30 comprises a number of machining segments 31, a basic body 32 and a tool fitting. The machining segments 31, which are used for abrasive removal, are also referred to as abrading segments, and the disk-shaped basic body 32 is also referred to as a pot. The abrading segments 31 are fixedly connected to the pot 32, for example by screwing, adhesive bonding, brazing or welding.

[0035] The abrasive disk 30 is connected via the tool fitting to a tool device and, in abrading operation, is driven by the tool device in a direction of rotation 34 about an axis of rotation 35. During the rotation of the abrasive disk 30 about the axis of rotation 35, the abrasive disk 30 is moved over a workpiece to be machined, the movement of the running perpendicular to the axis of rotation 35. The abrasive disk 30 removes the surface of the workpiece to be machined.

[0036] FIG. 4 shows a machining tool taking the form of a cut-off grinding chain 36. The cut-off grinding chain 36 comprises a number of machining segments 37, a number of basic bodies 38 in the form of links, and a number of connecting links 39. The machining segments 37, which are used for cut-off grinding, are also referred to as cut-off grinding segments, and the basic bodies 38 in the form of links are also referred to as driving links.

[0037] The driving links 38 are connected via the connecting links 39. In the exemplary embodiment, the connecting links 39 are connected to the driving links 38 via rivet bolts. The rivet bolts allow a rotation of the driving links 38 relative to the connecting links 39 about an axis of rotation which runs through the center of the rivet bolts. The machining segments 37 are fixedly connected to the driving links 38, for example by screwing, adhesive bonding, brazing or welding.

[0038] The cut-off grinding chain 36 is connected via a tool fitting to a tool device and, in operation, is driven by the tool device in a direction of rotation. During the rotation of the cut-off grinding chain 36, the cut-off grinding chain 36 is moved into a workpiece to be machined.

[0039] FIGS. 5A-C show a machining segment 41 in a three-dimensional representation (FIG. 5A), in a view of an upper side of the machining segment 41 (FIG. 5B), and in a view of a side surface of the machining segment 41 (FIG. 5C).

[0040] The machining segment 41 corresponds in structure and composition to the machining segments 11A, 21A, 21B, 31, 37; the machining segment 11B taking the form of a drilling ring differs from the machining segment 41 by its annular structure. The machining segments can differ from one another in the dimensions and in the curvatures of the surfaces. The basic structure of the machining segments according to the invention is explained on the basis of the machining segment 41 and applies to the machining segments 11A, 11B of FIGS. 1A, 1B, to the machining segments 21A, 21B of FIGS. 2A, 2B, to the machining segment 31 of FIG. 3, and to the machining segment 37 of FIG. 4.

[0041] The machining segment 41 is built up from a machining zone 42 and a neutral zone 43. The neutral zone 43 is required if the machining segment 41 is intended to be connected to the basic body of a machining tool; in the case of machining segments which are connected to the basic body for example by brazing or adhesive bonding, the neutral zone 43 can be omitted. The machining zone 42 is built up from a first matrix material 44 and first hard material particles 45, and the neutral zone 43 is built up from a second matrix material 46 without hard material particles.

[0042] The term “hard material particles” covers all cutting means for machining segments; these especially include individual hard material particles, composite parts made up of multiple hard material particles, and coated or encapsulated hard material particles. The term “matrix material” covers all materials for building up machining segments in which hard material particles can be embedded. Matrix materials may consist of one material or be composed as a mixture of different materials.

[0043] Machining segments which are produced by the method according to the invention for further processing a green body have a layer with first hard material particles 45; further layers with first hard material particles 45 are not provided. “First hard material particles” refer to those hard material particles of the machining segment 41 which, after the production of the machining segment, have on the upper side a projection with respect to the first matrix material 44. Hard material particles which are completely embedded in the first matrix material 44 in the machining segment 41 do not come under the definition of the first hard material particles.

[0044] The machining segment 41 is connected by an underside 47 to the basic body of the machining tool. In the case of machining segments for core drilling and machining segments for abrasive removal, the underside of the machining segments is generally formed as planar, whereas the underside in the case of machining segments for sawing has a curvature in order to be able to fasten the machining segments to the curved end face of the annular or disk-shaped basic body.

[0045] The first hard material particles 45 are arranged in the first matrix material 44 according to a defined particle pattern (FIG. 5B) and have on an upper side 48, opposite from the underside 47, of the machining segment 41 a projection T.sub.1 with respect to the first matrix material 44. In the exemplary embodiment of FIGS. 5A-C, the machining segment 41 comprises a number of 9 first hard material particles 45 which project on the upper side 48. The number of the first hard material particles 45 and the defined particle pattern in which the first hard material particles 45 are arranged in the first matrix material 44 are adapted to the requirements of the machining segment 41.

[0046] The first hard material particles 45 generally derive from a particle distribution which is characterized by a minimum diameter, a maximum diameter and an average diameter. On account of the particle distribution of the first hard material particles 45 between the minimum and maximum diameter, the projections of the first hard material particles 45 can vary correspondingly. In the exemplary embodiment, all first hard material particles 45 have a projection of more than 400 μm with respect to the surrounding first matrix material 44.

[0047] The machining tools according to the invention that are shown in FIGS. 1A, 1B, FIGS. 2A, 2B, FIG. 3 and FIG. 4 and are intended for the machining of concrete materials have a defined direction of rotation. When considered in the direction of rotation of the machining tool, a distinction can be drawn between a front-side region and a rear-side region of a hard material particle 45. On account of its geometry with a planar underside, the machining segment 41 is suitable as a drilling segment for the core drill bit 10A.

[0048] The direction of rotation 14 of the core drill bit 10A defines a front-side region 51 and a rear-side region 52. The machining of concrete materials occurs in the front-side regions 51 of the first hard material particles 45, and the machining rate depends substantially on the size of the projection of the first hard material particles 45 in the front-side regions 51. The first hard material particles 45 have in the front-side region 51 a front-side projection T.sub.front and in the rear-side region a rear-side projection T.sub.back, which correspond in the exemplary embodiment. Alternatively, the first hard material particles 45 may have different front-side projections T.sub.front and rear-side projections T.sub.back.

[0049] The machining segment 41 is produced from a green body 53 which is further processed to form the machining segment 41. In a first embodiment, the green body 53 is compressed to form a compact body 54, which is further processed to form the machining segment 41, and, in a second embodiment, the green body 53 is further processed directly to form the machining segment 41.

[0050] FIGS. 6A, 6B show the green body 53 which is built up from the first matrix material 44 and the first hard material particles 45, and the compact body 54 which is produced by compressing the green body 53. The green body 53 is compacted under the action of pressure until the compact body 54 has substantially the final geometry of the machining segment 41. Examples of suitable methods for achieving an action of pressure on the green body 53 are cold-pressing methods or hot-pressing methods. In the case of cold-pressing methods, the green body 53 is exclusively subjected to an action of pressure, while in the case of hot-pressing methods the green body 53 is subjected not only to the action of pressure but also to an action of temperature up to temperatures of about 200° C. The compact body 54 is further processed under the action of temperature, for example during sintering or by infiltration, to form the machining segment 41.

[0051] FIGS. 7A-C show some tool components which are used during the further processing of the green body 53 to form the machining segment 41. The tool components include a bottom punch 61, a die-plate 62 and a top punch 63, the bottom punch 61 also being referred to as the first press punch and the top punch 63 as the second press punch. FIGS. 7B and 7C show the top punch 63 in detail.

[0052] The green body 53 is built up in the die-plate 62 with a cross-sectional area that corresponds to the desired geometry of the green body 53. The die-plate 62 has on the underside a first opening, into which the bottom punch 61 can be moved, and on the upper side a second opening, into which the top punch 63 can be moved. The top punch 63 has depressions 64 in a pressing surface which are arranged to correspond to the defined particle pattern of the first hard material particles 45.

[0053] The green body 53 is built up from the bottom up, that is to say from the underside 47 to the upper side 48. The first matrix material 44 is poured into the die-plate 62 by means of a filling shoe until the desired filling height is reached. The first hard material particles 45 are placed according to the defined particle pattern in the first matrix material 44 into the surface of the first matrix material 44 and embedded in the first matrix material 44 to a desired embedding depth. The green body 53 is further processed by means of the bottom punch 61 and the top punch 63.

[0054] The method according to the invention for producing a green body is used to produce green bodies 53 in which the first hard material particles 45 have a projection on the upper side with respect to the first matrix material 44. By means of the special top punch 63, the machining segments 41 which are suitable for the dry machining of concrete materials can be produced. The depressions 64 in the pressing surface of the top punch 63 are necessary to ensure that the projection of the first hard material particles 45 on the upper side 48 is maintained during compression or hot pressing.

[0055] Direct contact between the first hard material particles 45 and the depressions 64 of the top punch 63 can give rise to increased wear of the top punch 63. In order to reduce the wear of the top punch 63, direct contact between the first hard material particles 45 and the top punch 63 should be avoided. A measure which is suitable is the use of encased first hard material particles 45.

[0056] The use of encased first hard material particles has the advantage that the first hard material particles 45 do not come into direct contact with the top punch 63, and the wear of the top punch 63 can be reduced. The first matrix material 44 can be used as the casing material for the first hard material particles 45. Alternatively, a second matrix material may be used as the casing material for the first hard material particles 45, the second matrix material being different from the first matrix material 44. When a casing material that is different from the first matrix material 44 is used, matrix materials with different wear properties can be used. The casing material serves for protecting the top punch 63 during compression or hot pressing and should be able to be removed as quickly as possible from the finished machining segment in order to expose the first hard material particles 45 which machine the concrete material.

[0057] Depending on the wear properties of the first matrix material 44, increased wear of the first matrix material 44 on the side surfaces of the machining segment can occur during the machining of a base material with the machining segment 41 as a result of friction with the base material. This wear can be reduced by second hard material particles. The second hard material particles may be admixed with the first matrix material 44 as randomly distributed particles, or the second hard material particles are placed in the first matrix material 44 according to a defined second particle pattern. The second hard material particles are placed in particular in the region of the side surfaces of the machining segment 41.