EP2785495B1 - Grinding tool and method for producing same - Google Patents

Description

The invention relates to a grinding tool, in particular a cutting disk, with a matrix, in particular with a sintered metal matrix, and diamonds embedded in the matrix. Furthermore, a method for producing the grinding tool according to the invention is to be specified.

Such grinding tools are state of the art and are used for example in the AT 506 578 B1 , the EP 1 297 928 A1 , the GB 1 374 513 A , the FR 2 149 833 A5 , the WO 2010/031089 A1 and the WO 91/10538 A1 described. The abrasive action of these tools is based on the diamonds sticking out of the matrix a little and in contact with the object to be ground.

The abrasive effect can be adversely affected essentially by two effects: First, it can lead to premature breaking out of the diamond from the matrix. On the other hand, the effect was observed that the areas - viewed in the direction of grinding - "clog up" in front of the diamonds during the grinding process and thus the possibility of intervention of the diamonds is lost.

The object of the present invention is to avoid these disadvantages and to provide a comparison with the prior art improved grinding tool of the type mentioned, and a method for producing the same, wherein the grinding tool according to the invention is characterized in particular by an improved grinding action and increased life.

This object is achieved by the features of the two independent claims 1 and 8, respectively.

It is thus provided according to the invention that at least the majority of the diamonds are each assigned at least one wear-promoting particle and / or at least one wear-inhibiting particle, wherein the at least one wear-promoting particle or the at least one wear-inhibiting particle is likewise embedded in the matrix. Furthermore, it is provided that the grinding tool has a preferred grinding direction, and that in each case the at least one wear-promoting particles in the grinding direction before the diamond, which is assigned, is embedded in the matrix, or that in each case at least one wear-inhibiting particles in the grinding direction behind the diamond to which it is associated is embedded in the matrix. The at least one wear-promoting particle then ensures that the region of the bond of the diamond in the matrix-seen in the grinding direction of the grinding tool-wears out sufficiently in front of the diamond, thus preserving the possibility of engagement of the diamond. Conversely, the at least one wear-inhibiting particle in each case causes the wear of the rear region, seen in the grinding direction of the grinding tool, to reduce the binding of the diamond in the matrix and thereby prevent premature break-out of the diamond from the matrix.

The described effect of the respective at least one wear-promoting particle or of the at least one wear-inhibiting particle can furthermore be increased by the fact that the at least one wear-promoting particle has a smaller distance from the grinding contact surface of the grinding tool than the diamond to which it is assigned or, as is provided according to the invention, in each case the at least one wear-inhibiting particle has a greater distance from the sliding contact surface with respect to the diamond to which it is assigned. In this way, during the abrading of the grinding tool taking place during the grinding process, the at least one wear-promoting particle first of all comes into contact with the object to be ground, thereby breaks out and gives it something below arranged diamonds free. If this diamond is additionally assigned a wear-inhibiting particle which is arranged somewhat below the diamond, then this anti-wear particle causes a stabilization of the bond of the diamond in the matrix.

According to a preferred embodiment it can be provided that the at least one wear-promoting particle at least partially, preferably entirely, consists of pre-sintered granules, preferably of a binder phase and embedded molybdenum disulfide and / or graphite powder. The binder phase may consist at least partially, preferably entirely, of copper, cobalt, iron, bronze or nickel. In alternative embodiments, the at least one wear-promoting particle is at least partially, preferably wholly, glass spheres, mineral granules (ceramics or ceramic fracture) or mineral fracture (e.g., soapstone, limestone, chamotte, silicates, carbonates, nitrides, sulfides).

The at least one wear-inhibiting particle is preferably at least partially, preferably entirely, of hard metal grit, corundum, silicon carbide and / or boron nitride.

Furthermore, it has been found to be advantageous if the at least one wear-promoting particle and / or the at least one wear-inhibiting particle has a particle size between 250 μm and 600 μm. It is thus slightly smaller than the grain size preferably used in the diamonds of 350 microns to 700 microns.

It is also proposed that the grinding tool comprises at least one grinding segment, wherein the at least one grinding segment is arranged on at least one carrier body, preferably made of steel. In this case, the at least one abrasive segment can be welded or soldered to the at least one carrier body, for example.

• in einem ersten Verfahrensschritt eine Matrixschicht aus einem pulverförmigen, sinterbaren Material gebildet wird,
• in einem zweiten Verfahrensschritt Diamanten in einem vorbestimmten Setzmuster auf die Matrixschicht gesetzt werden,
• in einem dritten Verfahrensschritt jeweils wenigstens ein verschleißförderndes Partikel und/oder wenigstens ein verschleißhemmendes Partikel in einem vorbestimmten Abstand relativ zu wenigstens der Mehrzahl der Diamanten auf die Matrixschicht gesetzt wird,
• in einem vierten Verfahrensschritt die mit den Diamanten und dem jeweils wenigstens einen verschleißfördernden Partikel bzw. dem jeweils wenigstens einen verschleißhemmenden Partikel versehene Matrixschicht verpresst wird, und
• in einem abschließenden Verfahrensschritt ein Sinterungsprozess durchgeführt wird.

Protection is also desired for a method for producing the grinding tool according to the invention, the method being characterized in that

• in a first process step, a matrix layer is formed from a pulverulent, sinterable material,
• in a second method step diamonds are placed in a predetermined setting pattern on the matrix layer,
• in a third method step, at least one wear-promoting particle and / or at least one wear-inhibiting particle are placed on the matrix layer at a predetermined distance relative to at least the majority of the diamonds,
• in a fourth process step, the matrix layer provided with the diamonds and the respectively at least one wear-promoting particle or the respectively at least one wear-inhibiting particle is pressed, and
• in a final process step, a sintering process is performed.

In an advantageous embodiment of the method, further matrix layers are successively applied as long as possible before the concluding process step, and the second, third and fourth process steps are repeated in each case until a predetermined width has been reached.

Furthermore, it can be provided that, prior to the second method step, recesses for receiving the diamonds and / or the respectively at least one wear-promoting particle or the respectively at least one wear-inhibiting particle are formed in the matrix layer.

Finally, with regard to short process times, it has turned out to be advantageous if at least the second and third process steps are carried out simultaneously.

Fig. 1

eine schematisch dargestellte Draufsicht eines bevorzugten Ausführungsbeispiels des erfindungsgemäßes Schleifwerkzeugs in Form einer Trennscheibe,

Fig. 2a

eine schematisch dargestellte Draufsicht eines ersten bevorzugten Ausführungsbeispiels eines Schleifsegments,

Fig. 2b

eine schematisch dargestellte perspektivische Ansicht des ersten bevorzugten Ausführungsbeispiels des Schleifsegments aus Fig. 2a,

Fig. 3

eine schematisch dargestellte Draufsicht eines zweiten bevorzugten Ausführungsbeispiels eines Schleifsegments,

Fig. 4

eine schematisch dargestellte Draufsicht eines dritten bevorzugten Ausführungsbeispiels eines Schleifsegments,

Fig. 5

eine schematisch dargestellte Draufsicht eines vierten bevorzugten Ausführungsbeispiels eines Schleifsegments,

Fig. 6

ein schematisch dargestelltes Flussdiagramm zur Illustration einer bevorzugten Ausführungsform des Verfahren zur Herstellung des erfindungsgemäßen Schleifwerkzeugs, und

Fig. 7a - 7d

eine schematisch dargestellte Abfolge zweier Verfahrensschritte, bei denen zuerst die Diamanten und anschließend verschleißfördernde Partikel auf eine Matrixschicht gesetzt werden.

Further details and advantages of the present invention will be explained in more detail below with reference to the description of the figures with reference to the exemplary embodiments illustrated in the drawings. Show:

Fig. 1

1 is a schematic plan view of a preferred embodiment of the grinding tool according to the invention in the form of a cutting disk;

Fig. 2a

1 is a schematic top view of a first preferred embodiment of a grinding segment;

Fig. 2b

a schematically illustrated perspective view of the first preferred embodiment of the grinding segment Fig. 2a .

Fig. 3

1 is a schematic top view of a second preferred embodiment of a grinding segment;

Fig. 4

1 is a schematic plan view of a third preferred embodiment of a grinding segment;

Fig. 5

1 is a schematic plan view of a fourth preferred embodiment of a grinding segment;

Fig. 6

a schematically illustrated flow diagram illustrating a preferred embodiment of the method for producing the grinding tool according to the invention, and

Fig. 7a - 7d

a schematically illustrated sequence of two process steps, in which first the diamonds and then wear-promoting particles are placed on a matrix layer.

Fig. 1 shows a preferred embodiment of a grinding tool 1 according to the invention in the form of a cutting disc. This is generally a circular, flat disc, which is usually used as part of an angle or cutting grinder for workpiece machining. In addition, cutting discs are also used in wall and floor cutting machines. One distinguishes between different types of cutting discs, where it in the case shown is a so-called diamond cutting disc, which is used in particular for the processing of natural stone, concrete or asphalt. In detail, the cutting disc 1 consists of a support body 7 in the form of a steel disc (disc blade), on the outer circumference of a series of abrasive segments 6 are arranged. The abrasive segments 6 are welded to the outer edge 11 of the carrier body 7. The support body 7 further comprises receiving or mounting holes 10 for installation of the cutting wheel 1 in an angle or cut grinder or in a wall or joint cutting machine. The individual abrasive segments 6 are separated by slots 12. In use, the blade 1 is rotated, wherein the blade 1 has a preferred grinding direction D. Cutting discs are usually used for separating material sections and therefore have a very narrow sliding contact surface S, which extends over the end face of the cutting wheel 1.

In the Fig. 2a For example, one of the abrasive segments 6 is shown enlarged in a first preferred embodiment. The basic component of the grinding segment 6 is a sintered metal matrix 2, in which a plurality of diamonds 3 are embedded. The diamonds 3 have a grain size K _d of 350 microns to 700 microns. The distance between the centers of the diamonds 3 is 1 to 2 mm. In this first preferred embodiment of the grinding segment 6, the majority of the diamonds 3 are each assigned a wear-promoting particle 4, the wear-promoting particles 4 being embedded in the matrix 2 before the diamonds 3, as seen in the grinding direction D. In addition, they have a smaller distance A _f to the sliding contact surface S with respect to the diamonds 3 to which they are associated. The grain size K _{f of} the wear-promoting particles 4 is 250 μm to 600 μm. It should also be pointed out that individual diamonds 3, in particular in the edge region of the grinding segment 6, are each assigned no wear-promoting particle 4. The distance of the center of the diamonds 3 to the center of their respective assigned wear-promoting particles 4 corresponds approximately to the grain size K _{f of} the wear-promoting particles 4th

In the Fig. 2b is a schematic perspective view of the grinding segment 6 of the Fig. 2a shown. It can be seen that the abrasive segment 6 in this case consists of four layers 2 ', which are arranged one above the other and constructed in much the same way as the upper layer facing the observer. The layer structure is indicated by the three dashed dividing lines. The width of the grinding segment 6 is provided with the reference symbol b.

In the Figures 3 . 4 and 5 three further preferred embodiments of the grinding segment 6 are shown. Unlike the first, in the Fig. 2a and 2 B to be seen embodiment is in the Fig. 3 to be seen embodiment, characterized in that the plurality of diamonds 3 are each associated with two wear-promoting particles 4. In this way, the wear-promoting effect of these particles 4 (see introduction to the description) is increased even further. It should be noted that in this embodiment, each of the two wear-promoting particles 4 - seen in the grinding direction D of the grinding tool - are embedded in the matrix 2 in front of the diamond to which they are associated, and that one of the two particles 4 opposite the diamond 3 a smaller distance A _f to the sliding contact surface S and the other of the two particles 4 has a greater distance A _f to the sliding contact surface S.

That in the Fig. 4 embodiment shown is characterized in that the diamond 3 is assigned in each case a wear-inhibiting particles 5, these wear-inhibiting particles 5 are each - embedded in the matrix 2 - seen in the direction of grinding D - behind the diamond 3, which they are assigned. In addition, they have a greater distance A _h to the sliding contact surface S with respect to the diamonds to which they are associated. The grain size K _{h of} the wear-inhibiting particles 5 is again between 250 .mu.m and 600 .mu.m.

The fourth, in the Fig. 5 Seeing embodiment of the grinding segment 6 is finally characterized in that the plurality of diamonds 3 is assigned in each case at least one wear-promoting particle 4 and a wear-inhibiting particles 5, wherein the wear-promoting particles 4 each in the grinding direction D before the diamond 3, which it is assigned is embedded in the matrix 2 and the wear-inhibiting particles 5 are each embedded in the matrix 2 in the grinding direction D behind the diamond 3 to which it is associated.

Fig. 6 shows in a schematic flow diagram, the five main process steps for the production of the grinding tool according to the invention. In a first method step i, a matrix layer of a pulverulent, sinterable material is formed. In a second method step ii diamonds are placed in a predetermined setting pattern on the matrix layer. In a third method step iii, depending on the embodiment, at least one wear-promoting particle and / or at least one wear-inhibiting particle are placed on the matrix layer at a predetermined distance relative to at least the majority of the diamonds. In a fourth method step iv, the matrix layer provided with the diamonds and the respectively at least one wear-promoting particle or the respectively at least one wear-resistant particle is pressed and finally sintered in a concluding process step v.

Furthermore, in the preferred embodiment of this method, further matrix layers are successively applied before the concluding process step v and the second, third and fourth process steps ii, iii and iv are repeated until a predetermined width b is reached (cf. Fig. 2b ). In addition, in the preferred embodiment of the method prior to the second method step ii, recesses for receiving the diamonds and the respective at least one wear-promoting particle or the respectively at least one wear-inhibiting particle are formed in the matrix layer.

With regard to the first method step i, it should be noted that the matrix layer is formed by first pouring the powder-form sinterable material into a segment mold via a portioning device. After pouring, the surface is scraped to obtain a flat surface. Subsequently, the metal powder layer is slightly pressed. In the course of this pressing, the recesses for receiving the diamonds and the respectively at least one wear-promoting particle or each a wear-inhibiting particle in the matrix layer are formed at the same time, said recesses being e.g. have the shape of conical or truncated pyramids.

With regard to the second and the third method steps ii and iii, it should be noted that the diamonds and the wear-promoting particles or the wear-inhibiting particles are easily pressed into the metal powder when placed on the matrix layer.

With regard to the time sequence of the method steps described, it should be noted that, depending on the type and number of setting devices used, the second and third method steps ii and iii are also carried out simultaneously. Basically, in the context of the invention, preference is given to using either two different setting devices, one for the diamonds and the other for the wear-promoting and / or wear-inhibiting particles, or there is only a single setting device which can handle both the diamonds and the wear-promoting and / or or in the latter case, the setting of the diamonds and the wear-promoting and / or wear-inhibiting particles is carried out successively or simultaneously.

In case of FIGS. 7a to 7b the method is carried out by means of a common setting device 13, the diamonds 3 and - in the case shown - the wear-promoting particles 4 successively on the matrix layer. 2 be set. In the FIGS. 7a to 7d schematically an exemplary implementation of the second and the third method step is shown. Not shown is the preceding first method step, in which the metal matrix layer 2 is formed and then recesses 8 and 9 are formed for receiving the diamonds 3 and their associated wear-promoting particles 4.

In the illustrated setting device 13 is substantially a perforated plate 14 which is provided with holes 15, wherein the bores 15 are penetrated by pins 17 which are connected to a die plate 16. In the interior 19 of the perforated plate 14, a negative pressure is generated, which propagates to the mouths of the bores 15, so that there each one diamond 3, a wear-promoting particle 4 or a wear-inhibiting particles 5 (not shown) can be recorded. In order to place the sucked diamonds 3, the wear-promoting particles 4 or the wear-inhibiting particles 5 on the preformed metal powder layer 2, the perforated plate 14 is moved so close to the metal powder layer 2, that there is still no suction of powder. If the diamonds 3, the wear-promoting particles 4 or the wear-inhibiting particles 5 were simply dropped from the height thus caused, the diamonds 3, the wear-promoting particles 4 or the wear-inhibiting particles 5 would not be uniform 3, the wear-promoting particles 4 and the wear-inhibiting particles 5 are ejected by moving the die plate 14 in a suitable guide 18 by means of the pins 17. In the illustrated setting device 13, the diamonds 3, the wear-promoting particles 4 or the wear-inhibiting particles 5 are therefore not pressed into the metal powder, as may also be provided (see above).

Following the setting of the diamonds 3 ( Fig. 7a and 7b ) and the setting of the wear-promoting particles 4 in the case shown in addition to the majority the diamond 3 ( Fig. 7c and 7d ), the metal powder layer 2 provided with the diamonds 3 and the wear-promoting particles 4 is compressed, if necessary a further metal powder layer 2 is applied and the second, third and fourth process steps are repeated and finally the grinding segment is finished in a sintering process.

Claims (11)

1. A grinding tool (1), in particular a cutting disc, comprising a matrix (2), in particular a sintered metal matrix, and diamonds (3) embedded in the matrix (2), characterised in that

   - associated with at least the majority of the diamonds (3) is at least one respective wear-promoting particle (4) and/or at least one respective wear-inhibiting particle (5),

   - the at least one wear-promoting particle (4) and the at least one wear-inhibiting particle (5) respectively is also embedded in the matrix (2),

   - the grinding tool (1) has a preferred grinding direction (D), and

   - the at least one respective wear-promoting particle (4) is embedded in the matrix (2) upstream of the diamond (3) with which it is associated in the grinding direction (D) and the at least one respective wear-inhibiting particle (5) respectively is embedded in the matrix (2) downstream of the diamond (3) with which it is associated in the grinding direction (D), and

   - the grinding tool (1) has a grinding contact surface (S) which is towards the article to be ground in the condition of use, wherein the at least one respective wear-inhibiting particle (5) is at a greater spacing (A_h) relative to the grinding contact surface (S) in relation to the diamond (3) with which it is associated.
2. The grinding tool (1) as set forth in claim 1 characterised in that the grinding tool (1) has a grinding contact surface (S) which is towards the article to be ground in the condition of use, characterised in that the at least one respective wear-promoting particle (4) is at a smaller spacing (A_f) relative to the grinding contact surface in relation to the diamond (3) with which it is associated.
3. The grinding tool (1) as set forth in claim 1 or claim 2 characterised in that the at least one wear-promoting particle (4) comprises at least partially and preferably entirely pre-sintered granular material, preferably a binding phase and incorporated molybdenum disulfide and/or graphite powder.
4. The grinding tool (1) as set forth in claim 3 characterised in that the binding phase comprises at least partially and preferably entirely copper, cobalt, iron, bronze or nickel.
5. The grinding tool (1) as set forth in one of claims 1 through 4 characterised in that the at least one wear-inhibiting particle (5) comprises at least partially and preferably entirely hard metal grit, corundum, silicon carbide and/or boronitride.
6. The grinding tool (1) as set forth in one of claims 1 through 5 characterised in that the at least one wear-promoting particle (4) and/or the at least one wear-inhibiting particle (5) is of a grain size (K_f, K_h) of between 250 µm and 600 µm.
7. The grinding tool (1) as set forth in one of claims 1 through 6 characterised in that the grinding tool (1) includes at least one grinding segment (6), wherein the at least one grinding segment (6) is arranged on at least one carrier body (7), preferably of steel.
8. A process for producing a grinding tool (1) as set forth in one of claims 1 through 7 characterised in that in a first process step (i) a matrix layer (2') is formed from a sinterable material in powder form, in a second process step (ii) diamonds (3) are placed on the matrix layer (2') in a predetermined placement pattern, in a third process step (iii) at least one respective wear-promoting particle (4) and/or at least one respective wear-inhibiting particle (5) is placed on the matrix layer (2') at a predetermined spacing relative to at least the majority of the diamonds (3), in a fourth process step (iv) the matrix layer (2') provided with the diamonds (3) and the at least one respective wear-promoting particle (4) and the at least one respective wear-inhibiting particle (5) respectively is pressed, and in a concluding process step (v) a sintering process is carried out.
9. The process as set forth in claim 8 characterised in that prior to the concluding process step (v) further matrix layers (2') are successively applied and the respective second, third and fourth process steps (ii, iii, iv) are respectively repeated until a predetermined width (b) is reached.
10. The process as set forth in claim 8 or claim 9 characterised in that prior to the second process step (ii) recesses (8, 9) are formed in the matrix layer (2') to receive the diamonds (3) and/or the at least one respective wear-promoting particle (4) and the at least one respective wear-inhibiting particle (5) respectively.
11. The process as set forth in one of claims 8 through 10 characterised in that at least the second and third process steps (ii, iii) are carried out simultaneously.

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