Patent Application
20230264259
The present invention relates to a method for producing a machining segment.
Machining tools, such as core drill bits, saw blades, abrasive disks and cut-off grinding chains, comprise machining segments that are attached to a tubular, disk-shaped or annular basic body, the machining segments being connected to the basic body by welding, brazing or adhesive bonding. Depending on the machining method of the machining tool, machining segments that are used for core drilling are referred to as drilling segments, machining segments that are used for sawing are referred to as sawing segments, machining segments that are used for abrasive removal are referred to as abrading segments and machining segments that are used for cut-off grinding are referred to as cut-off grinding segments.
Machining segments for core drill bits, saw blades, abrasive disks and cut-off grinding cutting chains are produced from a matrix material and hard material particles, where the hard material particles can be randomly distributed or are arranged according to a defined particle pattern in the matrix material. In the case of machining segments with randomly distributed hard material particles, the matrix material and the hard material particles are mixed, and the mixture is poured into a suitable mold and further processed to form the machining segment. In the case of machining segments with hard material particles arranged in a defined manner, a green body is built up in layers from matrix material, in which the hard material particles are arranged according to the defined particle pattern. In the case of machining segments that are to be welded to the basic body of the machining tool, the structure comprising a machining zone and a neutral zone has proven to be successful, since some combinations of matrix material and basic body cannot be welded. The machining zone is built up from a first matrix material and the neutral zone is built up from a second matrix material, which is different from the first matrix material and can be welded to the basic body.
In the case of machining tools which can be designed as a core drill bit, saw blade, abrasive disk or cut-off grinding chain and are intended for the wet or dry machining of concrete materials, increased wear on the side surfaces of the machining segments can occur as a result of friction with the substrate. The wear depends in particular on the wear properties of the first matrix material. It is known from EP 1 297 928 B1 to reduce wear on the side surfaces of the machining segments by second hard material particles which are admixed with the first matrix material as randomly distributed hard material particles. It is disadvantageous that the second hard material particles are completely embedded in the first matrix material. In order to expose the second hard material particles on the side surfaces, the machining segments must be sharpened on the side surfaces.
It is an object of the present invention to provide a method for producing a green body for a machining segment with which machining segments that have low wear on the side surfaces of the machining segments can be produced. Both in the production of the green body and in the further processing of the green body to form the machining segment, conventional tool components are to be used; the use of special tool components should be avoided. In addition, no re-working of the machining segments on the side surfaces should be required.
The method for producing a machining segment from a powdered or granular first matrix material, first hard material particles, which are arranged according to a defined first particle pattern, and second hard material particles, which are arranged according to a defined second particle pattern, is characterized according to the invention in that, when compacting the green body, a first film of a film material is arranged between the first press punch and the green body and a second film of the film material is arranged between the second press punch and the green body, the film material having a hardness which is less than the hardness of the first matrix material.
Machining segments that are produced by the method according to the invention are produced in a three-stage process: in a first stage, a green body is built up from the first matrix material, the first hard material particles and second hard material particles, the first and second hard material particles being arranged in the first matrix material according to a defined first and second particle pattern; in a second stage, the green body is compacted under the action of pressure to form a compact body and, in a third stage, the compact body is further processed under the action of temperature to form the machining segment.
Machining segments that are created by means of the method according to the invention for producing a machining segment have on the side surfaces a projection of the second hard material particles with respect to the first matrix material. The method according to the invention for producing a machining segment is distinguished by the fact that the green bodies are built up horizontally, the building-up direction runs perpendicularly to the vertical direction between the underside and upper side of the machining segment and, when compacting, a first and a second film of a film material is used, the hardness of the film material being less than the hardness of the first matrix material. The term “film material” includes all materials in film form that are suitable for producing a projection of the second hard material particles on the side surfaces of the machining segment. In order to be able to create the projection of the second hard material particles, the film material must have a hardness which is less than the hardness of the first matrix material.
The projection of the second hard material particles on the first and second side surfaces of the machining segments is created by means of the first film and the second film, the film material of the first and second films being different from the first matrix material. The first film is arranged between the first press punch, which forms the first side surface, and the green body, and the second film is arranged between the second press punch, which forms the second side surface, and the green body. Conventional press punches can be used as the first press punch and the second press punch; no special press punches with indentations in the pressing surface are required.
Preferably, the second hard material particles are completely embedded in the first matrix material on the first side surface and the second side surface when the green body is built up. The first film, which is arranged between the first press punch and the green body, and the second film, which is arranged between the second press punch and the green body, ensure that, after compaction, the second hard material particles have a projection with respect to the first matrix material on the first and second side surfaces. The method according to the invention has the advantage that the projection of the second hard material particles is created during the production of the machining segment and no re-working of the machining segments on the side surfaces is required.
In a first embodiment of the method, the first film and second film are removed from the compact body after compaction. When the first and second films are removed from the compact body after compaction, the compact body is further processed to form the machining segment by free-form sintering without further shaping.
In a second, alternative embodiment of the method, the compact body with the first film and second film are further processed to form the machining segment. When the compact body with the first film and second film are further processed to form the machining segment, the properties of the film material, in particular the melting temperature and the flash point, determine the behavior of the film material during further processing.
In a first variant, the film material is selected so that the melting temperature of the film material is lower than the sintering temperature of the first matrix material. If the melting temperature of the film material is lower than the sintering temperature of the first matrix material, the film material changes its state when it is heated up and liquefies before the first matrix material is sintered. The liquid film material distributes itself in the first matrix material during the sintering process and can support the sintering process as an infiltrate.
In a second variant, the film material is selected so that the flash point of the film material is lower than the sintering temperature of the first matrix material. If the flash point of the film material is lower than the sintering temperature of the first matrix material, the film material changes its state when it is heated up and evaporates before the first matrix material is sintered.
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.
In the drawing:
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 that 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.
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 that is used for core drilling is also referred to as 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.
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.
The drilling shaft 12A, 12B is of a one-piece form in the exemplary embodiment of
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.
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.
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.
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.
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.
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.
The production of a machining segment 51 (see, e.g.
The machining zone 54 is built up from a powdered or granular first matrix material 56, first hard material particles 57, which are arranged according to a defined first particle pattern, and second hard material particles 58, which are arranged according to a defined second 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.
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.
The machining segment 51 comprises the first and second hard material particles 57, 58, 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 being adapted to the requirements of the machining segment 51. Depending on the wear properties of the first matrix material 56, increased wear of the first matrix material 56 on the side surfaces of the machining segment 51 can occur during the machining of a substrate with the machining segment 51 as a result of friction with the substrate. This wear is reduced by the second hard material particles 58.
The first hard material particles 57 and second hard material particles 58 generally originate from particle distributions which are characterized by a minimum diameter, a maximum diameter and an average diameter. In the exemplary embodiment of
The machining segment 51 is connected by an underside 61 to the basic body of a machining tool. In the case of the machining segment 51 shown in
The green body 52 shown in
When the green body 52 is compacted, a first film 67 with a first layer thickness d1 is arranged between the first press punch 63 and the green body 52 and a second film 68 with a second layer thickness d2 is arranged between the second press punch 65 and the green body 52. The first film 67 and second film 68 consist of a film material 69, which is different from the first matrix material 56. The film material 69 has a hardness which is less than the hardness of the first matrix material 56. Because the hardness of the film material 69 is less than the hardness of the first matrix material 56, when compacting between the first press punch 63 and second press punch 65, the projection of the second hard material particles 58 is created on the first side surface 64 and second side surface 66. The method according to the invention has the advantage that the projection of the second hard material particles is created during the production of the machining segment and no re-working of the machining segments on the side surfaces is required.
In the case of the compact body 53 shown in
The machining segment 71 differs from the machining segment 51 of
The first hard material particles 77 generally originate from a first particle distribution with a first average diameter and the second hard material particles 58 originate from a second particle distribution with a second average diameter. In the exemplary embodiment of
The machining segment 71 is connected by an underside 81 to the basic body of a machining tool. In the case of the machining segment 71 shown in
The green body 72 shown in
When the green body 72 is compacted, a first film 87 with a first layer thickness d1 is arranged between the first press punch 83 and the green body 72 and a second film 88 with a second layer thickness d2 is arranged between the second press punch 85 and the green body 72. The first and second films 87, 88 consist of a film material 89, which is different from the first matrix material 76. The film material 89 has a hardness which is less than the hardness of the first matrix material 76. Because the hardness of the film material 89 is less than the hardness of the first matrix material 76, when compacting between the first press punch 83 and second press punch 85, the projection of the second hard material particles 78 is created on the first side surface 84 and second side surface 86.
In the case of the compact body 73 shown in
If the melting temperature Tmelt of the film material 89 is lower than the sintering temperature Tsinter of the first matrix material 76, when the compact body 73 is heated up the film material 89 melts before the first matrix material 76 has reached its sintering temperature Tsinter; the liquid film material 89 distributes itself in the first matrix material 76 during the sintering process and can support the sintering process as an infiltrate. If the flame point Tflame of the film material 89 is lower than the sintering temperature Tsinter of the first matrix material 76, when the compact body 73 is heated up the film material 89 evaporates before the first matrix material 76 has reached its sintering temperature Tsinter.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20181945.5 | Jun 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/065622 | 6/10/2021 | WO |
