EP0452618A1 - Process and apparatus for preparing an abrasive body for grinding tools - Google Patents

Abstract

A process and an apparatus for carrying out the process are proposed, by means of which the abrasive bodies (45) which are to be attached to a tool holder (55) and are for the grinding of materials are produced. The individual abrasive body (45) comprises a plurality of layers of sinter metal powder or sinter metal platelets (11'') as well as a plurality of layers of natural and/or artificial abrasive particles (12''), the layers being introduced in alternating sequence into a female mould corresponding to the abrasive body (45). The abrasive particles or diamond chips (12'') are received by a suction plate which is provided with bores arranged geometrically with respect to one another, is designed similarly to a template and is subjected to a vacuum, and are deposited onto the next-following sintered metal platelet (11''). To achieve a homogeneous structure, the abrasive body blanks prepared in this way are sintered at an appropriate temperature and under an appropriate pressure. <IMAGE>

Description

The invention relates to a method and to a device provided with a carrier element for in-plane and height-adjustable feed movements of receiving and transfer elements for the production of grinding wheels for tools, in particular for rotatingly driven tools for the removal of materials, in which Tools the individual grinding body has a structure made from a mixture of metal powder and natural and / or artificial, abrasive materials.

In the known tools, in particular in the segment-like grinding wheels for drill bits, circular saws or the like, the individual grinding wheels designed for processing stone, concrete and reinforced concrete are provided with grinding grains of natural or artificially produced industrial diamonds embedded in sintered metal.
In the manufacture of such abrasive products, a metal powder with a certain grain size and with diamond chips or other abrasive materials in a certain ratio are used in a certain proportion trained device (shaker mixer) mixed and then cold-pressed in a suitably designed form into a so-called shaped body (green body) and then sintered at a suitable temperature in a manner known per se. The tools are equipped with the segment-like grinding tools, for example, by welding.
The problem with the grinding tools produced by this method is that even with sufficient mixing, so-called nests with a high or less high concentration of diamond chips result, so that on the one hand the cutting performance and on the other hand the surface properties of the processed objects are unsatisfactory and also the individual grinding elements only have a relatively short service life (breaking out of the diamond chips) and therefore do not meet today's high technical requirements. The causes of the so-called formation of nests are based, on the one hand, on the residual magnetism that is still present and, on the other hand, on the static charge of the diamond chips that occurs in particular when mixing.

The invention relates to the production of grinding wheels, the object of the invention being to avoid the disadvantages of the prior art and to specify a method and an apparatus for carrying out the method by means of which a predeterminable, homogeneous structure of the individual grinding wheel and better removal properties can be achieved.

The method according to the invention is characterized in that, in order to achieve a largely homogeneous structural structure in an alternating sequence, several layers of sintered metal and several layers of abrasive materials with abrasive grains arranged in a certain geometrical formation with respect to one another are stored one above the other in a negative form designed in accordance with the abrasive body are, the individual abrasive body pressed and compressed and then sintered according to the known sintering process at the appropriate temperature and high pressure.

The inventive device according to the preamble of claim 5 is characterized by a first vacuum-applied head piece and at least a second vacuum-applied head piece, the first head piece with a suction plate for receiving and holding a sintered metal layer and the second head piece with a suction plate Receiving and holding a number of abrasive grains arranged in a geometric formation relative to one another.

Further features of the invention emerge from the following description in conjunction with the drawing and the individual patent claims.

Fig. 1

eine schematisch und in Ausgangsstellung dargestellte Vorrichtung zur Herstellung von Schleifkörpern,

Fig. 2

ein Teilstück der Vorrichtung gemäss Fig.1 in einer ersten Übergabestellung,

Fig. 3

ein Teilstück der Vorrichtung gemäss Fig.1 in einer zweiten Übergabestellung,

Fig. 4

ein Teilstück der Vorrichtung gemäss Fig.1 in einer dritten Stellung,

Fig. 5

ein erstes, in Schnittansicht dargestelltes Aufnahme- und Übergabe-Kopfstück für die Vorrichtung gemäss Fig.1,

Fig. 6

eine in schematischer Draufsicht dargestellte Saugplatte für das Kopfstück gemäss Fig.5,

Fig. 7

ein zweites, in Schnittansicht dargestelltes Aufnahme- und Übergabekopfstück für die Vorrichtung gemäss Fig.1,

Fig. 8

mehrere in Draufsicht dargestellte Ausführungsbeispiele von Saugplatten für das Kopfstück gemäss Fig.7,

Fig. 9

den in grösserem Massstab und als Schnittbild dargestellten strukturellen Aufbau eines Schleifkörpers, und

Fig.10

ein in perspektivischer Ansicht dargestelltes Bohrkronen-Werkzeug mit daran angeordnete Schleifkörpern.

The invention is described below with reference to the drawing. It shows:

Fig. 1

1 shows a device for producing grinding wheels, shown schematically and in the starting position,

Fig. 2

a portion of the device according to Figure 1 in a first transfer position,

Fig. 3

a portion of the device according to Figure 1 in a second transfer position,

Fig. 4

a portion of the device according to Figure 1 in a third position,

Fig. 5

a first, shown in sectional view receiving and transfer headpiece for the device according to Figure 1,

Fig. 6

4 shows a suction plate for the head piece according to FIG. 5, shown in a schematic plan view,

Fig. 7

a second, shown in sectional view receiving and transfer headpiece for the device according to Figure 1,

Fig. 8

several embodiments of suction plates for the head piece according to FIG. 7 shown in plan view,

Fig. 9

the structural structure of a grinding wheel shown on a larger scale and as a sectional view, and

Fig. 10

a drill bit tool shown in perspective view with grinding wheels arranged thereon.

1 shows a system and device 75, schematically and as a functional diagram, for producing grinding wheels for tools, for example for drill bits, circular saw blades or the like, which are designed for the machining of corresponding workpieces made of stone, marble, concrete or the like.
The device 75 essentially comprises a carrier element 4 with functional elements 1, 2 and 3 arranged thereon at a distance from one another and correspondingly assigned containers 10, 11 and 12.
The two functional elements 1 and 2 are designed as receiving and transfer headpieces and are each operatively connected to a vacuum generator 5 via a correspondingly designed supply line 1 'and 2'. The receiving and transfer head 1 is referred to below as the first head 1 and the receiving and transfer head 2 as the second head 2.
The vacuum generator 5 can be controlled by means not shown, so that the suction force on the head piece 1 or on the head piece 2 can be briefly interrupted separately from one another for the transfer of the parts held thereon. Furthermore, the vacuum generator 5 is preferably designed and controllable in such a way that when the vacuum is interrupted, a brief, slight burst of compressed air is released to loosen the headpiece 1, 2 held elements can be generated. The special design of the two head pieces 1 and 2 will be described later in detail with reference to FIGS. 5 to 8.
The functional element 3 is designed as a compression head piece and is operatively connected to a pressure source 6 via a supply line 3 '. The compression header is hereinafter referred to as the third header 3.

A support unit 4 is provided, for example, with a slide unit of handling technology (industrial robot) or the like which can be adjusted in the direction of the arrow X and X 'by means not shown. The head pieces 1, 2 and 3 arranged on the carriage unit 4 can be adjusted relative to the carriage unit 4 in the direction of the arrows Z and Z 'in addition to the movement oriented in the arrow direction X, X'. The above-mentioned movements of the individual elements in the direction of the arrow X, X 'and Z, Z' are preferably carried out independently of one another, but there is also the possibility of combining the movements with one another if necessary.

The first container 10, shown in perspective in FIG. 1, is designed inside as a negative mold 45 'for a grinding wheel blank 45 to be produced. The special design of the grinding wheel 45 (FIG. 4) will be described later.
The second container 11 is designed as a storage container for a large number of thin sintered metal plates 11 ′ lying one above the other. The prefabricated plates 11 ′ are designed in accordance with the shape of the grinding wheel 45 to be manufactured.
The third container 12 is provided as a storage container for fine-grained, abrasive materials, for example for diamond grains 12 'or diamond chips or the like. The container 12 is preferably operatively connected to a schematically illustrated shaking device 13. The container 12 is preferably heated to a corresponding temperature by means of a device (not shown) for neutralizing so-called residual magnetism of the diamond grains 12 '. By means of the shaking device 13, the diamond grains 12 'are kept in a loosened state by permanent vibration.

1 shows the two head pieces 1 and 2 in the position in which they have already been lifted out of the assigned container 11 or 12 in the direction of arrow Z 'in their starting position, so that the transport in the direction of arrow X' can take place. The individual platelets 11 ″ held on the first head piece 1 and received from the container 11 are held by the suction force S and the diamond grains 12 ″ held on the second head piece 2 and received from the container 12 are held by the suction force S ′.

2 shows a section of the device 75 in a first transfer position and the first head piece 1 can be seen with the sintered metal plate 11 ″ arranged thereon and still held in this phase by the suction force S, which is inserted into the negative form of the container 10 . By briefly switching off the suction force on the first head piece 1, the plate 11 ″ is placed in a correspondingly placed manner. During this phase, the suction force remains on the second head piece 2 and the diamond grains 12 ″ are thereby held on the head piece 2. However, the head piece 1 can also be designed such that instead of a sintered metal plate 11 ″ which is solid per se, a layer of sintered metal powder can be taken up and introduced into the container 10.

3 shows a section of the device 75 in a second transfer position and the first head piece 1 removed from the container 10 and the second head piece 2 introduced into the container 10 in this phase with the diamond grains held in this phase by the suction force S 'can be seen 12 ''.

As soon as the head piece 2 with the diamond grains 12 ″ has reached a certain position, for example the last inserted sintered metal plate 11 ″ or the last sintered metal powder layer has been contacted, the suction power on the head piece 2 is temporarily switched off and the diamond grains 12 ″ are opened the assigned plate 11 '' or powder layer.
The diamond grains 12 ″ can be released from a suction plate arranged on the second head piece 2 by means of a brief, slight blast of compressed air. The blast of compressed air may, however, only be so great that the placement of the diamond grains 12 ″ on the correspondingly assigned plate 11 ″ is ensured while maintaining a certain geometric formation. The formation of the diamond grains 12 ″ is achieved by the special design of the suction plate arranged on the second head piece 2.
The above-described alternate layering of the individual sintered metal platelets 11 ″ and the layers of the diamond grains 12 ″ is described and repeated until a predetermined height of the grinding wheel 45 to be produced is reached.

At this point, it should be pointed out that, in a manner not shown in more detail, in addition to the second head piece 2, further head pieces 2 can be arranged on the carrier element 4. The head pieces 2 are each formed with differently designed suction plates for a differentiated layer formation of diamond grains. The formation of the individual suction plates with the different formations for the diamond grains 12 ″ will be described in detail in connection with FIG. 8.

4 shows a further section of the device 75 and the grinding body 45 stacked in the container 10 can be seen, which is scanned by an adjustable measuring and control element 70 when a predetermined height is reached. From The control device 70 is terminated by means of corresponding signals, the piling operations carried out essentially by the two head pieces 1 and 2.
The multi-layer grinding wheel 45 is then compressed and compressed by the third head piece 3, which has already been introduced into the container 10 in FIG. 4, and by the force exerted by the pressure source 6 and oriented in the direction of the arrow P.
The individual abrasive bodies 45, which are produced according to the above steps, which essentially correspond to a compression molding process, are then pressed in a device, not shown, according to the known process of metallurgy under high pressure and sintered at a corresponding temperature, which results in a homogeneous, structural Structure of the grinding wheel is reached.

In FIG. 5, the first head piece 1 is shown on a larger scale and in a sectional view as an exemplary embodiment, and one recognizes a funnel-shaped housing 21 provided with a vacuum chamber 24, which has a channel part 21 'narrowing in the suction direction S in the upper region and a lower part 21' in the lower region Area is provided with a holding part 21 '' for receiving a suction plate 22. In the holding part 21 ″, the suction plate 22, which is held therein by means not shown and is provided with an approximately flat surface 22 ′ and is penetrated by a plurality of bores 23, is arranged.
FIG. 6 shows the suction plate 22 shown in plan view according to line VI-VI in FIG. 5 and designed as an annular segment with the bores 23 arranged at a distance from one another. The arrangement of the bores 23 in this suction plate 22 can be chosen as desired, but preferably evenly the area of the suction plate 22 can be distributed.
The suction plate 22 can be used, in particular, to receive a powdered sintered metal layer on that facing away from the vacuum chamber 24 Side be provided with a concave surface 22 'in profile cross section.

7 shows the second head piece 2 on a larger scale and in a sectional view and one can see a funnel-shaped housing 25 provided with a vacuum chamber 26, which has a channel part 25 'narrowing in the suction direction S' in the upper region and in the lower region is provided with a holding part 25 '' for receiving a correspondingly designed suction plate 30, 35, 40 or 41. The individual suction plate 30, 35, 40 or 41 designed in the form of an annular segment is penetrated by a number of bores and is held in the holding part 25 ″ of the housing 25 by means not shown. The fastening device, not shown, for the respective suction plate 30, 35, 40 or 41 in the holding part 25 ″ is preferably designed such that the individual suction plates are interchangeable.

FIG. 8 shows a top view of the individual suction plates 30, 35, 40 and 41 with the different formations or structures of the through bores. The special arrangement of the holes on the respective suction plate (template), which are essentially related to a center line M, is described below:
The suction plate 30 has bores 28 ′, 28 ″ arranged at a uniform distance from one another in the region of the outer arch edge 30 ′ and in the region of the inner arch edge 30 ″. The two bores 28 ', 28''arranged opposite each other on a line 28 facing the center are each assigned three further bores 29', 29 '', which together form a group of bores 29 arranged in a star shape. Of the individual group of holes 29, one hole 29 'is arranged on the center line M and the other two holes 29''are arranged at the same distance from the center line M. The two side end pieces of the suction plate 30 are at this embodiment with a rounding 27,27 '.
The suction plate 35 has bores 32 ′, 32 ″ arranged at a uniform distance from one another in the region of the outer arch edge 35 ′ and in the region of the inner arch edge 35 ″. Furthermore, further bores 34 are provided on the center line M corresponding to the bores 32, 32 ″. The three bores 32 ', 32''and 34 arranged opposite each other on a line 32 directed towards the center are each assigned three further bores 33', 33 '', which together form a group 33 arranged in a star shape. Of the individual hole group 33, one hole 33 'is arranged on the center line M and the other two holes 33''are arranged at the same distance from the center line M. The two lateral end pieces 31, 31 'of the suction plate 35 are wedge-shaped in this exemplary embodiment.
In the suction plate 40, bores 37 are provided on the outer arc edge 40 'at a uniform distance from one another and on the inner arc edge 40''are bores 38 which are arranged at a uniform distance from one another. The bores 38 arranged on the inner arch edge 40 ″ are offset with respect to the bores 37 arranged on the outer arch edge 40 ′. The bores 37 and 38 are assigned further bores 37 'and 38' arranged on the center line M and further bores 37 '' and 38 ''. In this exemplary embodiment, the two lateral end pieces 36, 36 'of the suction plate 40 are designed as an edge oriented straight to the center (not shown) of the circular ring.
The suction plate 41 largely corresponds to the suction plate 40 described above and the bores 37 'and 38' arranged on the center line M and the correspondingly assigned bores 37 '' and 38 '' can be seen. Deviating from the suction plate 40, no holes are provided in the suction plate 41 on the outer and inner curved edges 41 ′ and 41 ″.

Due to the special and above-described, geometrical arrangement of the bores in the suction plates 30, 35, 40 and 41, on the one hand a correspondingly ordered receptacle and on the other hand a correspondingly ordered transfer of the diamond grains 12 ″ and thus a largely homogeneous structure of the grinding wheel 45 are achieved. Due to the inevitable accumulation of the diamond grains 12 '' in the area of the center line of the individual suction plates 30, 35, 40 and 41, the outer edges of the grinding body 45 are first ground off during drilling, which results in an approximately wedge-shaped grinding surface on the side facing the workpiece and a better one Centering of the respective drill bit is achieved.

FIG. 9 shows the structural structure of the grinding body 45, which is shown on a larger scale and as a sectional view, and the diamond grains 12 ″, which are arranged offset to one another and embedded in the sintered metal layers 11 ″, can be seen. On one side of the individual grinding body 45, the sintered metal layer 47 is formed in multiple layers for welding attachment to a holding body 55 (FIG. 10).

The individual tool, designated in its entirety by 50, is provided, as in the exemplary embodiment shown as a drill bit in FIG. 10, with a plurality of grinding bodies 45 arranged uniformly distributed over the circumference. The grinding bodies 45 are arranged, for example, at a distance 46 from one another on a tubular body 55 and fastened to them by soldering or welding.

• a) Absenken des ersten Kopfstückes 1 gemäss Pfeilrichtung Z in den Behälter 11 und Erfassen sowie Halten eines Sintermetall-Plättchens 11'' oder des Sintermetall-Pulvers mittels der an der Saugplatte 22 des Kopfstückes 1 vorliegen den Saugwirkung und Anheben des Kopfstückes 1 gemäss Pfeilrichtung Z' in die Grundstellung;
• b) Absenken des zweiten Kopfstückes 2 in den Behälter 12 und Erfassen sowie Halten einer Vielzahl Diamantkörner 12'' mittels der an der Saugplatte 30,35,40 oder 41 des Kopfstückes 2 vorliegenden Saugwirkung und Anheben des Kopfstückes 2 gemäss Pfeilrichtung Z' in die Grundstellung;
• c) Betätigung des Trägerelements 4 in Pfeilrichtung X und Absenken des ersten Kopfstückes 1 in den Behälter 10 und Unterbruch der Saugwirkung an der Saugplatte 22 für die Ablage des Sintermetall-Plättchens 11'' im Behälter 10 gemäss Fig.2 und Anheben des Kopfstückes 1 in die Grundstellung;
• d) Betätigen des Trägerelements 4 in Pfeilrichtung X und Absenken des zweiten Kopfstückes 2 in den Behälter 10 und Unterbruch der Saugwirkung an der Saugplatte 30,35,40,41 für die Ablage der Diamantkörner 12'' auf dem Sintermetall-Plättchen 11'' im Behälter 10 gemäss Fig.3 und Anheben des Kopfstücks 2 in die Grundstellung;
• e) Durchführung der einzelnen Arbeitsschritte von a) bis d) bis zur Erreichung einer gewünschten Höhe des Schleifkörpers 45 und Zusammenpressen sowie Verdichten des Schleifkörper-Rohlings durch das dritte Kopfstück 3 gemäss Fig.4,
• f) Behandlung der einzelnen Schleifkörper-Rohlinge bei entsprechender Temperatur und entsprechend hohem Druck nach dem an sich bekannten Sinterverfahren der Metallurgie.

The method for producing the individual grinding body 45 in the device 75 is carried out according to the following essential work steps:

• a) Lowering the first head piece 1 in the direction of arrow Z into the container 11 and grasping and holding a sintered metal plate 11 ″ or the sintered metal powder by means of the suction effect on the suction plate 22 of the head piece 1 and the lifting of the head piece 1 according to arrow direction Z 'into the basic position;
• b) Lowering the second head piece 2 into the container 12 and grasping and holding a plurality of diamond grains 12 ″ by means of the suction effect on the suction plate 30, 35, 40 or 41 of the head piece 2 and lifting the head piece 2 according to the direction of the arrow Z ′ into the basic position ;
• c) Actuation of the carrier element 4 in the direction of the arrow X and lowering of the first head piece 1 into the container 10 and interruption of the suction effect on the suction plate 22 for depositing the sintered metal plate 11 ″ in the container 10 according to FIG. 2 and lifting the head piece 1 in the basic position;
• d) actuating the carrier element 4 in the direction of arrow X and lowering the second head piece 2 into the container 10 and interrupting the suction on the suction plate 30, 35, 40, 41 for depositing the diamond grains 12 ″ on the sintered metal plate 11 ″ in Container 10 according to Figure 3 and lifting the head piece 2 in the basic position;
• e) Execution of the individual work steps from a) to d) until a desired height of the grinding wheel 45 is reached and compression and compression of the grinding wheel blank by the third head piece 3 according to FIG. 4,
• f) treatment of the individual abrasive body blanks at the appropriate temperature and correspondingly high pressure according to the known sintering process of metallurgy.

Claims (10)

Process for the manufacture of grinding tools for tools, in particular for rotatingly driven tools for the machining of materials, in which tools the individual grinding tool has a structure made from a mixture of metal powder and natural and / or artificial, abrasive materials, characterized in that for the achievement A largely homogeneous structural structure of the abrasive body (45) in an alternating sequence of several layers of sintered metal and several layers of abrasive materials with abrasive grains (12 '') arranged in a specific geometric formation in a negative shape (10) corresponding to the abrasive body are stored, the individual abrasive body (45) being pressed and compressed and then sintered according to the known sintering method at the appropriate temperature and correspondingly high pressure. Method according to claim 1, characterized in that corresponding layers of abrasive materials with different, geometrically arranged abrasive grains (12 '') are applied to the individual sintered metal layers in an alternating sequence. Method according to one of claims 1 and 2, characterized in that the sintered metal layers picked up from appropriately assigned containers and the abrasive grains picked up in geometrical formation are held by vacuum on appropriately designed elements until they are deposited in the rodent shape. Method according to one of claims 1 to 3, characterized in that the individual sintered metal layers in Form of sintered metal plate (11 '') are introduced into the negative mold (10). Method according to one of claims 1 and 2, characterized in that the sintered metal layers or sintered metal plates (11 '') held by vacuum on the correspondingly formed element and the abrasive grains (12 '') by a short, short burst of compressed air from the Element loosened and the abrasive grains are placed in a stable position on the assigned sintered metal layer. Method according to one of claims 1 to 5, characterized in that the prefabricated sintered metal flakes (11 '') and the abrasive grains (12 '') deposited thereon in layers in certain formations together form a rounded off at least at one end piece of the finished abrasive body (45) , wedge-shaped or straight edge. Device, consisting of a carrier element (4) for in-plane and height-adjustable feed movements of several receiving and transfer elements for carrying out the method according to one of the preceding claims 1 to 4, characterized by a first head piece (1) charged with vacuum and at least a second head piece (2) charged with vacuum, the first head piece (1) having a suction plate (22) for receiving and holding a sintered metal layer or a sintered metal plate (11 '') and the second head piece (2) having a Suction plate (26, 30, 35, 40) for receiving and holding a number of abrasive grains (12 '') arranged in a geometrical formation with respect to one another. Apparatus according to claim 7, characterized in that the first head piece (1) and the suction plate (22) arranged thereon are designed as a segment-like circular ring and the suction plate (22) is distributed over a number Through holes (23) with a vacuum chamber (24) of the head piece (1) is connected. Apparatus according to claim 7, characterized in that the second head piece (2) and the suction plate (26; 30; 35; 40) arranged thereon are designed as a segment-like circular ring and the respective suction plate (26; 30; 35; 40) over several, Through bores arranged in groups and largely symmetrically with respect to a center line (M) are connected to a vacuum chamber (27) of the head piece (2). Apparatus according to claim 9, characterized in that the suction plate (26; 30 and 35) in addition to the through holes arranged in groups along the center line (M) further apart at a distance along the outer and inner arc edge (26 ', 26' '; 30' , 30 '' and 35, '35 '') arranged bores (28 ', 28' '; 32', 32 '' and 37,37 ') is provided.

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