Method for producing a green body and method for further processing the green body to form a machining segment

Abstract

Method for producing a green body for a machining segment (51) from a powdered or granular first matrix material (56) and first hard material particles (57), the machining segment being connected by an underside (61) to a basic body of a machining tool. The machining segment (51) has a projection (Δ) of the first hard material particles (57) on an upper side (62) opposite from the underside (61).

Claims

1-10. (canceled)

11. A method for producing a green body for a machining segment from a powdered or granular first matrix material and first hard material particles arranged according to a defined first particle pattern, the machining segment being connected by an underside to a basic body of a machining tool, the method comprising a sequence of a first step and a second step carried out N times, N≥1, where: in the first step, applying a matrix layer having a first region and a second region, the first matrix material being applied in the first region and a powdered or granular supporting material different from the first matrix material being applied in the second region; and in the second step, arranging the first hard material particles in the matrix layer according to the defined first particle pattern, the first hard material particles being arranged in a transitional region between the first region and the second region.

12. The method as recited in claim 11 wherein the supporting material has a melting temperature higher than the sintering temperature of the first matrix material.

13. The method as recited in claim 11 wherein the supporting material has a melting temperature lower than the sintering temperature of the first matrix material.

14. The method as recited in claim 11 wherein, after the Nth sequence, an upper matrix layer comprising an upper matric layer first region and an upper matrix layer second region is applied, wherein the first matrix material is applied in the upper matrix first region and the supporting material is applied in the upper matrix second region.

15. The method as recited in claim 15 wherein the supporting material has a melting temperature higher than the sintering temperature of the first matrix material.

16. The method as recited in claim 15 wherein the supporting material has a melting temperature lower than the sintering temperature of the first matrix material.

17. A method for forming a machining segment, the method comprising: further processing the green body produced by the method as recited in claim 11 to form the machining segment.

18. The method as recited in claim 17 wherein further processing includes compacting the green body under the action of pressure to form a compact body and further processing the compact body to form the machining segment.

19. The method as recited in claim 18 wherein the compact body is further processed to form the machining segment by free-form sintering or hot pressing.

20. The method as recited in claim 17 wherein the green body is further processed to form the machining segment by free-form sintering or hot pressing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Exemplary embodiments of the invention are described hereinafter with reference to the drawing. It is not necessarily intended for this to illustrate the exemplary embodiments to scale; rather, the drawing is produced in a schematic and/or slightly distorted form where this is useful for purposes of explanation. It should be taken into account here that various modifications and alterations relating to the form and detail of an embodiment may be undertaken without departing from the general concept of the invention. The general concept of the invention is not limited to the exact form or the detail of the preferred embodiment shown and described hereinafter or limited to subject matter that would be restricted compared to the subject matter claimed in the claims. For given dimensioning ranges, values within the stated limits should also be disclosed as limit values and should be able to be used and claimed as desired. For the sake of simplicity, the same reference signs are used hereinafter for identical or similar parts or parts having an identical or similar function.

[0026] In the drawing:

[0027] FIGS. 1A, B show two variants of a machining tool designed as a core drill bit;

[0028] FIGS. 2A, B show two variants of a machining tool designed as a saw blade;

[0029] FIG. 3 shows a machining tool designed as an abrasive disk;

[0030] FIG. 4 shows a machining tool designed as a cut-off grinding chain;

[0031] FIGS. 5A-C show a green body (FIG. 5A), which is compacted into a compact body (FIG. 5B) and is further processed to form a machining segment (FIG. 5C);

[0032] FIGS. 6A-E show the production of the green body of FIG. 5A by means of the method according to the invention for producing a green body;

[0033] FIGS. 7A, B show a green body (FIG. 7A), which is further processed to form a machining segment (FIG. 7B); and

[0034] FIGS. 8A-D show the production of the green body of FIG. 7A by means of the method according to the invention for producing a green body.

DETAILED DESCRIPTION

[0035] FIGS. 1A, B show two variants of a machining tool designed as 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”.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] The drilling shaft 12A, 12B in the exemplary embodiment of FIGS. 1A, B is of a one-piece form 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 and 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 design 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.

[0040] FIGS. 2A, B show two variants of a machining tool designed as 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”.

[0041] The first saw blade 20A comprises a plurality 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.

[0042] The second saw blade 20B comprises a plurality 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.

[0043] 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.

[0044] FIG. 3 shows a machining tool designed as 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.

[0045] 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 running perpendicular to the axis of rotation 35. The abrasive disk 30 removes the surface of the workpiece to be machined.

[0046] FIG. 4 shows a machining tool taking the form of a cut-off grinding chain 40. The cut-off grinding chain 40 comprises a number of machining segments 41, a number of basic bodies 42 in the form of links, and a number of connecting links 43. The machining segments 41, which are used for cut-off grinding, are also referred to as cut-off grinding segments, and the basic bodies 42 in the form of links are also referred to as driving links.

[0047] The driving links 42 are connected via the connecting links 43. In the exemplary embodiment, the connecting links 43 are connected to the driving links 42 via rivet bolts. The rivet bolts allow a rotation of the driving links 42 relative to the connecting links 43 about an axis of rotation which runs through the center of the rivet bolts. The machining segments 41 are fixedly connected to the driving links 42, for example by screwing, adhesive bonding, brazing or welding.

[0048] The cut-off grinding chain 40 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 40, the cut-off grinding chain 40 is moved into a workpiece to be machined.

[0049] The production of a machining segment 51, which has hard material particles with a projection with respect to the matrix material on its upper side, takes place with the aid of the method according to the invention for the production of a green body and the method for further processing the green body to form a machining segment. In a first stage, a green body 52 is produced; in a second stage, the green body 52 is compacted to form a compact body 53 and, in a third stage, the compact body 53 is further processed to form the machining segment 51. Alternatively, a green body can be produced in a first stage and further processed to form the machining segment in a second stage.

[0050] FIGS. 5A-C show the green body 52 (FIG. 5A), the compact body 53 (FIG. 5B) and the machining segment 51 (FIG. 5C). The machining segment 51 is built up from a machining zone 54 and a neutral zone 55. The neutral zone 55 is required if the machining segment 51 is to be welded to the basic body of a machining tool and the combination of matrix material and basic body cannot be welded; in the case of weldable combinations of matrix material and basic body, there is no need for the neutral zone 55.

[0051] The machining zone 54 is built up from a powdered or granular first matrix material 56 and first hard material particles 57 which are arranged according to a defined first particle pattern, and the neutral zone 55 is built up from a powdered or granular second matrix material 59. 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. The term “hard material particles” covers all cutting agents 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.

[0052] The machining segment 51 corresponds in structure and composition to the machining segments 11A, 21A, 21B, 31, 41; the machining segment 11B designed as a drilling ring differs from the machining segment 51 by its annular structure. The machining segments can differ from one another in the dimensions and in the curvatures of the surfaces. The structure of the machining segments is explained on the basis of the machining segment 51 and applies to the machining segments 11A, 21A, 21B, 31, 41.

[0053] The machining segment 51 comprises the first hard material particles 57, which are arranged in the first matrix material 56. “First hard material particles” refer to those hard material particles of the machining segment 51 that machine a substrate, the number of the first hard material particles 57 and the defined first particle pattern according to which the first hard material particles 57 are arranged in the first matrix material 56 being adapted to the requirements of the machining segment 51.

[0054] The machining segment 51 is connected by an underside 61 to the basic body of a machining tool. In the case of machining segments for core drilling and in the case of 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 bodies. In the case of the machining segment 51 shown in FIG. 5C, the first hard material particles 57 are arranged according to the defined first particle pattern in the first matrix material 56 and have a projection Δ with respect to the first matrix material 56 on an upper side 62 opposite from the underside 61.

[0055] The green body 52 shown in FIG. 5A is built up from the first matrix material 56, the first hard material particles 57, the second matrix material 59 and a powdered or granular supporting material 63. The supporting material 63 is different from the first matrix material 56 and serves for covering the first hard material particles 57 during pressing.

[0056] The green body 52 is compacted under the action of pressure between a first press punch 64, which forms a first side surface 65 of the green body 52, and a second press punch 66, which forms a second side surface 67 of the green body 52. The pressing direction of the first press punch 64 and the second press punch 66 runs between the first and second side surfaces 65, 67. Examples of suitable methods for achieving an action of pressure on the green body 52 are cold-pressing methods or hot-pressing methods. In the case of cold-pressing methods, the green body 52 is exclusively subjected to an action of pressure, while in the case of hot-pressing methods the green body 52 is subjected not only to the action of pressure but also to an action of temperature up to temperatures of about 200° C.

[0057] The compact body 53 is further processed to form the machining segment 51 by free-form sintering or hot pressing. In the case of free-form sintering, there is an action of temperature on the compact body 53 and in the case of hot pressing there is an action of pressure and temperature. If the compact body 53 is further processed by free-form sintering, the green body 52 is compacted until the compact body 53 has substantially the final geometry of the machining segment 51. If the compact body 53 is further processed by hot pressing, the compact body 53 is shaped further during hot pressing.

[0058] The properties of the supporting material 63, in particular the melting temperature T.sub.melt, determine the behavior of the supporting material 63 during further processing. If the melting temperature T.sub.melt of the supporting material 63 is lower than the sintering temperature T.sub.sinter of the first matrix material 56, the supporting material 63 changes its powdered or granular state when it is heated up and liquefies before the first matrix material 56 is sintered; the liquid supporting material 63 can distribute itself in the first matrix material 56 during the sintering process and support the sintering process as an infiltrate. If the melting temperature T.sub.melt of the supporting material 63 is higher than the sintering temperature T.sub.sinter of the first matrix material 56, the supporting material 63 remains in its powdered or granular state when it is heated up and can be removed from the finished machining segment without any problem after the sintering process.

[0059] FIGS. 6A-E show the production of the green body 52 by means of the method according to the invention for producing a green body. The green body 52 is built up from the first matrix material 56, the first hard material particles 57, the second matrix material 59 and the supporting material 63.

[0060] The production of the green body 52 starts with a sequence of a first step and a second step, which can be carried out once or multiple times (N-fold with N≥1); in the case of the green body 52, the sequence of the first step and the second step is carried out twice. In the first step of the first sequence, a matrix layer 71 comprising a first region 72, a second region 73 and a third region 74 is applied, the first matrix material 56 being applied in the first region 72, the supporting material 63 being applied in the second region 73 and the second matrix material 59 being applied in the third region 74 (FIG. 6A); in the case of a green body without a neutral zone, the third region 74 is omitted. In the second step of the first sequence, the first hard material particles 57 are arranged in the matrix layer 71 according to the defined first particle pattern, the first hard material particles 57 being arranged in a transitional region 75 between the first region 72 and the second region 73 (FIG. 6B). FIGS. 6C and 6D show the green body 52 in the first step of the second sequence (FIG. 6C) and in the second step of the second sequence (FIG. 6D).

[0061] After the sequence of the first step and the second step has been carried out twice, an upper matrix layer 76 comprising a first region 77, a second region 78 and a third region 79 is applied, the first matrix material 56 being applied in the first region 77, the supporting material 63 being applied in the second region 78 and the second matrix material 59 being applied in the third region 79 (FIG. 6E). In the case of a green body without a neutral zone, the third region 79 is omitted.

[0062] FIGS. 7A, B show a machining segment 81 produced by the method according to the invention for producing a green body and the method for further processing the green body to form the machining segment. The machining segment 81 is in this case produced in two stages: In a first stage, a green body 82 is produced (FIG. 7A) and, in a second stage, the green body 82 is further processed to form the machining segment 81 (FIG. 7B).

[0063] The machining segment 81 differs from the machining segment 51 of FIG. 5C by the fact that the machining segment 81 is built up from a machining zone 84 and does not have a neutral zone. The machining zone 84 is built up from a first matrix material 86, first hard material particles 87 and second hard material particles 88. Depending on the wear properties of the first matrix material 86, increased wear of the first matrix material 86 on the side surfaces of the machining segment 81 can occur during the machining of a substrate as a result of friction. This wear can be reduced by the second hard material particles 88.

[0064] The machining segment 81 differs from the machining segment 51 of FIG. 5C by the fact that the machining segment 81 is built up from a machining zone 84 and does not have a neutral zone. The machining zone 84 is built up from a powdered or granular first matrix material 86, first hard material particles 87, which are arranged according to a defined first particle pattern, and second hard material particles 88.

[0065] The first hard material particles 87 and second hard material particles 88 generally originate from particle distributions which are characterized by a minimum diameter, a maximum diameter and an average diameter. The second hard material particles 88 may be admixed with the first matrix material 86 as randomly distributed particles, or the second hard material particles 88 are arranged in the first matrix material 86 according to a defined second particle pattern, the second hard material particles 88 being arranged in particular in the region of the side surfaces of the machining segment 81. In the case of the machining segment 81 shown in FIG. 7B, the second hard material particles 88 were admixed with the first matrix material 86 as randomly distributed particles.

[0066] The machining segment 81 is connected by an underside 91 to the basic body of the machining tool. A substrate is machined by first hard material particles 87, which are arranged on an upper side 92 opposite from the underside 91.

[0067] In the case of the machining segment 81 shown in FIG. 7B, the first hard material particles 87 are arranged in the first matrix material 86 according to a defined first particle pattern and have a projection Δ with respect to the first matrix material 86 on an upper side 92 opposite from the underside 91.

[0068] The green body 82 is produced analogously to the production of the green body 52, the application of the second matrix material being dispensed with. The green body 82 is built up from the first matrix material 86, the first hard material particles 87, the second hard material particles 88 and a powdered or granular supporting material 93. The supporting material 93 is different from the first matrix material 86 and serves for covering the first hard material particles 87 during pressing.

[0069] The green body 82 is further processed to form the machining segment 81 by free-form sintering or hot pressing. In the case of free-form sintering, the green body 82 is subjected to a temperature effect, and in the case of hot pressing there is an effect of pressure and temperature. The properties of the supporting material 93, in particular the melting temperature T.sub.melt, determine the behavior of the supporting material 93 during further processing. If the melting temperature T.sub.melt of the supporting material 93 is lower than the sintering temperature T.sub.sinter of the first matrix material 86, the supporting material 93 changes its powdered or granular state when it is heated up and liquefies before the first matrix material 86 is sintered; the liquid supporting material 93 can distribute itself in the first matrix material 86 during the sintering process and support the sintering process as an infiltrate. If the melting temperature T.sub.melt of the supporting material 93 is higher than the sintering temperature T.sub.sinter of the first matrix material 86, the supporting material 93 remains in its powdered or granular state when it is heated up and can be removed from the finished machining segment without any problem after the sintering process.

[0070] FIGS. 8A-D show the production of the green body 82 by means of the method according to the invention for producing a green body. The green body 82 is built up from the first matrix material 86, the first hard material particles 87, the second hard material particles 88 and the supporting material 93.

[0071] The production of the green body 82 starts with a sequence of a first step and a second step, which can be carried out once or multiple times (N-fold with N≥1); in the case of the green body 82, the sequence of the first step and the second step is carried out twice. In the first step of the first sequence, a matrix layer 101 comprising a first region 102 and a second region 103 is applied, the first matrix material 86 being applied in the first region 102 and the supporting material 93 being applied in the second region 103 (FIG. 8A). In the second step of the first sequence, the first hard material particles 87 are arranged in the matrix layer 101 according to the defined first particle pattern, the first hard material particles 87 being arranged in a transitional region 105 between the first region 102 and second region 103 (FIG. 8B). FIGS. 8C and 8D show the green body 82 in the first step of the second sequence (FIG. 8C) and in the second step of the second sequence (FIG. 8D).