EP1340593B1 - Grinding tool, especially cutting-off tool - Google Patents

Abstract

The grinding layer (5) contains a mixture of hollow grinding beads (13) and grinding particles (25). The grinding layer contains one or more types of hard grinding material (10) and one or more types of relatively soft grinding material (14), the hard material forming the grinding particles and the relatively soft material being located on the outer surfaces of the hollow beads. The binder is preferably a metal.

Description

The invention relates to a grinding tool, in particular a cutting tool.

Such a grinding tool is known in practice. It is as a so-called bound grinding tool formed, which has a grinding area in matrix form embedded with a binder and spatially dispersed Having abrasive materials.

Disc-cutting tools in disc shape, e.g. Cut-off wheels, come with free-hand grinding (Angle grinders), on hand-held Grinding machines (e.g., bar grinders) or else positively driven on stationary or unsteady machines (e.g., mobile floor cutters). Cutting tools are also in the form of drill bits, Cup wheels, flexible saw ropes and the like. Other Construction variants. Materials to be processed are disseminates hard building materials such as stone, brick, concrete, Ceramics or comparable composites, as well Metals. Here are in particular reinforced concrete or others reinforced with hard steel inserts or the like to call inhomogeneous materials.

The burden of these tools is marked by strong varying conditions of use. So leads the delivery the cut-off wheel by hand usually too strong alternating grinding forces and a high temperature, Shock and friction of the cutting surface. Farther strong wear-promoting effect the material, mechanical and geometric inhomogeneity of the separating workpieces.

As a result, the cutting performance may drop and that End of life of the cut-off wheel by a extensive removal of the binder and abrasive particles contained cutting zone can be reached quickly. Especially with relatively wear-resistant Binders can also be used after blunting the Abrasive particles and the associated increase in the Traganteils to a strong increase in temperature in the Abrasive zone come, which is usually irreversible Dulling of the grinding zone and thus the end of life of the tool.

For the purpose of optimizing the performance of cut-off wheels have been numerous species in the past and Combinations of abrasive particles, binding materials as well as designs of abrasive particle binder construction tested. For example, through pores in the Abrasive coating both chip spaces are created as well by reducing the carrying percentage the temperature in the Area of the grinding zone can be reduced. Furthermore, can the targeted introduction of pores the controlled Promote wear of the binder layer. Thereby can break out both dull grain and sharp Grain are released for participation in the grinding process.

GB 2 102 445 A discloses a bound Grinding tool containing an abrasive coating with a Binder and abrasive material, wherein the abrasive coating a mixture of abrasives and abrasive particles contains, the abrasive particles formed as a hollow grain balls and the abrasive coating is one or more types harder Abrasive and one or more types of low-hardness Contains abrasive.

EP 1 099 524 A2 shows a diamond cutting disc a rotatably driven disk body, on whose Outer circumference of an annular cutting ring of several regularly distributed in a circle diamond cutting segments is arranged. The cutting segments act as Abrasive article and are with abrasive particles, in particular diamond granules, corundum or the like occupied.

It is an object of the present invention that to improve previously known grinding tools.

The invention solves this problem with the features in the main claim.
The grinding tool according to the invention has the advantage that it offers a significantly better cutting performance and a longer service life. In particular, in this case also the cutting speed compared to previously known grinding tools can be increased and maintained for a long time.

Here is a special suitability for the beginning hard materials or building materials such as stone, Bricks, concrete, ceramics or similar Composites, but also metals. especially the critical inhomogeneous materials with variable Hardening, such as reinforced concrete or others with hard Steel inserts or the like reinforced materials can do better and processed with a longer tool life become.

When grinding tool according to the invention are in preferably peripheral or frontal Abrasive coating several types of different hardness Abrasive used, which is relevant to the Cutting process provided in harder abrasive in solid particle form directly into a metallic Binders existing matrix is involved. The less durable granular abrasive is part of Grain hollow sphere, which like the harder abrasive grain preferably incorporated metallic in the abrasive coating is. The less hardy, on the outer surface of the Grain hollow balls bonded abrasive grain has a lower Share in the machining process.

The hollow granules are self-sharpening and cause a Performance improvement, in which on the one hand the less hardy Abrasive grain of hollow granular beads among the above in the described specific loading conditions Grinding, in particular cutting, the mechanical Wear of the hard abrasive grain in particular by To reduce the absorption of pressure and shock loads can.

On the other hand arise along with the wear of the Hollow granules open ceramic porosity. These wise a sufficiently high mechanical and thermal Stability on, on the one hand the strength and the Ensuring composite of the entire abrasive coating. On the other hand, despite this strength they contribute to one controlled wear of the metallic binder in order to break out dulled grain and around new grain to engage. Furthermore, effect the pores created by the open hollow granules a reduction of the process temperature by the Wear content of the abrasive coating reduced, chip spaces created as well as ventilation and Verwirbelungsvorgänge be favored on the surface.

As hard abrasives are preferably diamond and cubic boron nitride while used as low-resistance abrasive corundum and silicon carbide have proven to be successful. As particularly advantageous, the Use of ceramic corundum prove because of this due to its microcrystalline structure a comparatively high toughness and therefore a good one Resistance to pressure and shock loads having.

In principle, a single hard abrasive can be used with a single less hard abrasive as an ingredient cooperate the hollow granule balls; but it can also Combinations of hard and less hard abrasives may be used, but preferably exclusively the less durable abrasive component of the Are hollow granules. This can be a controlled Grain wear allows and breaking out of Abrasive grain from the compared to a metallic one Binder less solid ceramic binder avoided become.

The size of the granular hollow spheres and of the bonded thereto Sub-hard abrasive may vary depending on the size of the hard abrasive can be selected. Accordingly, amounts the diameter of the hollow grain ball preferably 1 to 10 times the diameter of the hard abrasive, wherein the grain size of the less hard abrasive in the Magnitude of the hard abrasive is present.

A preferred embodiment for use in The grinding tool according to the invention is a 2-component hollow grain ball, the hollow body due its higher thermal and mechanical strength preferably made of ceramic material. A Another preferred embodiment is a 3-component hollow sphere, consisting of hollow sphere, Binders and abrasives. In a preferred Execution exist both the body of the hollow sphere as also the binder of a same or different ceramic material. The granular hollow sphere can in both cases from a fired ceramic Binding material, e.g. consist of Bindeton. The binder may alternatively be organic in nature.

The grinding tool can in different ways be designed. The abrasive coating in the form of one or multiple cutting segments present with a suitable support body made of other material suitable Way, e.g. by soldering, welding, sintering, etc. are connected. Alternatively, the abrasive coating with a Carrier be integrally connected, e.g. in form of entirely sintered grinding tool. The one-piece Training has the advantage that the tool design is very what is homogeneous for heat dissipation and the Stability is beneficial. By dividing into several sections with different Material composition allows the grinding tool optimally adapted to the respective application.

The grinding tool can be in any suitable shape present, e.g. in disc form for the removal or the Cutting loops, as a drill bit, as a cup wheel, but also as a flexible sawing wire with integrated grinding elements.

The grinding tool according to the invention may be one or more have additional cutting pads, e.g. out applied diamond particles or other very hard Abrasives exist.

In the subclaims are further advantageous Embodiments of the invention indicated.

Figur 1:

ein Schleifwerkzeug in Form einer Trennschleifscheibe mit einem Tragkörper und einem Schleifbelag in Draufsicht,

Figur 2:

einen Querschnitt durch die Trennschleifscheibe gemäß Schnittlinie II - II von Figur 1,

Figur 3:

eine andere Trennschleifscheibe in Draufsicht,

Figur 4:

ein Schleifwerkzeug in Form eines Sägeseils mit Schleifperlen,

Figur 5:

eine geschnittene und vergrößerte Darstellung einer Schleifperle,

Figur 6:

ein Schleifwerkzeug in Form einer Bohrkrone,

Figur 7:

ein Schleifwerkzeug in Form eines Schleiftopfes und

Figur 8:

einen vergrößerten schematischen Ausschnitt des Schleifbelags mit Kornhohlkugeln und Diamantpartikeln in einem Bindemittel.

The invention is illustrated by way of example and schematically in the drawings. In detail show:

FIG. 1:

a grinding tool in the form of a cut-off wheel with a supporting body and an abrasive coating in plan view,

FIG. 2:

3 shows a cross section through the cut-off wheel according to section line II - II of FIG. 1,

FIG. 3:

another cut-off wheel in plan view,

FIG. 4:

a grinding tool in the form of a sawing wire with abrasive beads,

FIG. 5:

a cut and enlarged view of a grinding bead,

FIG. 6:

a grinding tool in the form of a drill bit,

FIG. 7:

a grinding tool in the form of a grinding cup and

FIG. 8:

an enlarged schematic section of the abrasive coating with hollow beads and diamond particles in a binder.

In Figures 1 to 6 are different variants of Abrasive tools (1) shown as Abrasive tools are formed. The Abrasive tool can be used as a cut-off wheel (17), especially diamond cut-off wheel, drill bit (18) or formed as a flexible sawing wire (19). One another grinding tool (1), which for Surface treatment is used, e.g. one Be cup wheel (23) according to Figure 7.

The grinding tools (1) each have a supporting body (4) in a suitably different embodiment and at least one abrasive coating (5) at a suitable location of the Supporting body (4). The abrasive coating (5) is located preferably on the outer circumference or across also on adjacent edge area (especially at Cut-off tool) or on the front side (e.g. Grinding cup) of the supporting body (4). The abrasive coating (5) may consist of one or more abrasive elements (12), which are formed as separate parts and with the Supporting body (4) in any suitable manner, e.g. by Welding, soldering, Ansintern or the like connected are. Alternatively, the abrasive coating (5) integral with be connected to the support body (4).

The grinding tools (1) are bound as Abrasive tools are formed, which have an abrasive coating (5) in matrix form with a binder (15) and therein spatially distributed embedded abrasive bodies (13) and Having abrasive particles (25). In addition, hard and low-resistance abrasives (10,14) available. The thickness of the Abrasive coating (5) is considerably larger than the Diameter of the various abrasive particles contained (13) and abrasive (10,14).

As Figure 8 illustrates, the abrasive coating (5) has metallic binder (15) and several as Hollow grain balls (13) formed abrasive body, wherein it further comprises one or more types of hard abrasives (10) as abrasive particles (25) and one or more species low-hardness abrasive (14) contains.

The less hard abrasives (14) are on the outside Surface (24) of the hollow beads (13) arranged. in the Binders (15) are thus the hard abrasive particles (25) and the hollow grain balls (13) side by side and preferably evenly distributed as in a matrix embedded.

In the embodiment of Figure 8, the lower hardness Abrasive (14) only on the outer surface (24) the hollow granules (13) acting as supports arranged in the binder (15) otherwise the massive abrasive particles (25) from the harder Abrasives (10) are included. The hard and Inferior abrasives (10,14) can each case from a single unified material or from Mixtures of different materials exist. In a further modification, it is possible in the binder (15) besides the hard abrasive particles (10,25) too additionally embed low-hardness abrasives (14).

The binder (15) can be made of suitable powdery Metals and other aggregates. This can e.g. Iron, tungsten and / or bronze, these being Materials in pure form or in mixed form can.

The abrasive coating (5) is made of powdered or Particle form present starting materials in suitably produced by sintering.

The hard abrasives (10) have a suitable Particle shape and are preferably made of diamond or cubic boron nitride. The less durable abrasives (14) consist for example of corundum or Silicon carbide. You can in particular whole or partly made of ceramic corundum.

The less hard abrasives (14) preferably have a hardness of about 16 - 27 GPa (HV1). The hard ones Abrasives (10) have e.g. a hardness of about 45 GPa (HV1) with cubic boron nitride or a hardness of about 70 GPa (HV1) at diamond.

A preferred combination of hard and less hard Abrasive (10,14) is present when the Hardness difference between them at least 15 GPa (HV1) is.

The diameter of the hollow granular spheres (13) including the Mild-hard abrasive incorporated therein (14) is preferably 1 to 10 times the middle one Diameter of the or one of the hard ones Abrasive particles (10,25). The granular hollow spheres (13) preferably have a diameter of 1 mm or larger. The hard abrasive particles (10,25) have a Diameter of approx. 0.2 mm to 0.8 mm. In FIG. 8, the Ratios of the overview because of enlarged shown.

The diameter of the hollow sphere (13) arranged low-hardness abrasive (14) has preferably a smaller diameter than the hard ones Abrasive (10), preferably of the order of a third.

The abovementioned dimensions for the hardnesses and Sizes of grinding wheels (13) and abrasives (10,14) are preferred values of which in the context of Invention can also be deviated.

For the configuration of the hollow grain balls (13) there are different embodiments. These grinding wheels consist of at least two components, but can also have three components or more. Figure 8 shows e.g. in the lower right half of the diagram a schematic Hollow grain ball (13) in 2-component design, while in the left upper half of a grain hollow sphere (13) in 3-component version is shown.

In the one 2-component version of the jacket (24) the hollow grain ball (13) made of a ceramic or organic material, exist, because of the higher thermal and mechanical strength ceramic Material benefits. The grainy less hardy Abrasive (14), e.g. Korrund, is in this Embodiment directly in the jacket (24) or the Surface material of the hollow grain ball (13) involved., wherein a so-called two-component hollow grain ball is formed.

In the other 3-component variant, this is grainy low-durability abrasives (14) by means of an additional, preferably ceramic binder (16) with the outer Surface (24) of the hollow grain ball (13) connected. In this variant, it is recommended to the body of the Hollow grain ball (13) also made of a ceramic To train material.

FIG. 1 shows a cutting tool (1) in the form of a Cut-off wheel (17), in particular one Diamond cutting wheel. It has a support body (4) in the form of a level and essentially circular stem sheet made of steel or another Material having a central bore (2) for the Rotary axis (3) and a rotary drive connection and preferably a plurality of small hole-shaped ones Having perforations (7) in spiral lines (9) are arranged. The design can be in the Corresponding to EP-A-1 099 524 shown construction.

In the variant of Figure 3, the master sheet on a or both sides an additional, preferably also spirally arranged cutting surface (8) having, e.g. made of diamond particles, the preferably galvanically on the stem leaf surface are bound. The spiral shapes (9) are in the Drawings each in the direction indicated by arrow Turning direction bulged. With simpler ones Cut-off wheels, the openings (9) and the additional cutting pads (8) also omitted.

The abrasive coating (5) consists of several curved block-like or segment-shaped grinding elements (12), as a cutting ring evenly on the circumference of the Master sheet are arranged distributed and with the Outer edge of the stem sheet by laser welding or on other suitable type are connected. Figure 2 shows For this purpose, the cut-off wheel (17) in the aborted Cross section with the weld (6) between the outer edge the master blade and the butt-mounted abrasive element (12).

Alternatively, the abrasive coating (5) at the edge region of a Supporting body (4) be sintered and this in Cross-section U-shaped, wherein he also on the edge side wall regions of the supporting body (4) extends. Figure 2 shows this arrangement schematically with dashed lines.

The set apart in the circumferential direction at a distance and separated by undercuts (11) in the stem edge Sanding elements (12) have on their exposed sides Grinding surfaces on which the granular hollow spheres (13) and the Hard as well as low-hardness abrasives (10,14) are effective become.

In Figures 4 and 5, a grinding tool (1) in the form of a bending elastic sawing cable (19) shown. Of the Supporting body (4) is here by a wire core (20) formed throughout or in places of one Coil spring (21) is enclosed, in places the abrasive coating (5) forming in the longitudinal direction detached abrasive elements (12) is applied. The Sanding elements (12) form the so-called abrasive beads or cutting beads of the sawing wire (19). The soul (20), the Spring (21) and also parts of the abrasive coating (5) are surrounded by an elastic sheath (20), the is made of a suitable plastic, which is attached to the the aforementioned parts are molded or molded. The Sawing cable (19) can be a training accordingly WO 98/35778.

FIG. 6 shows a variant of the grinding tool (1) in FIG Shape of a so-called drill bit (18) shown. Of the Supporting body (4) has a substantially cylindrical here tubular and cup-like shape, at the free frontal Edge of the abrasive coating (5) in the form of several evenly distributed in a circle and circumferentially spaced abrasive elements (12) is arranged. The Sanding elements (5) can intercommunicate in the foot area be connected to form a toothed slip ring, which is shown in the upper half of Figure 6. Alternatively, the grinding elements (5) individually arranged and directly connected to the support body (4) be what indicated in the lower half of Figure 6 is.

The support body (4) can be made of metal, plastic or a consist of other suitable material, the Sanding elements (12) in a suitable permanent or possibly interchangeable with the support body (4) are connected. In the embodiment shown, the grinding elements have (12) a curved shape and are in the circumferential direction aligned. Alternatively, the grinding elements (12) have a substantially radial orientation.

FIG. 7 shows a further variant of a grinding tool (1), which here as a curved or flat cup (23) is formed. The support body (4) has e.g. a cup-shaped with a central hole (2). Of the Abrasive coating (5) consists here again of several block-shaped grinding elements (12) on the front side of the cup wheel (23), i. at the bottom of a Outer ring and possibly also on connecting webs permanently or are arranged interchangeably. The grinding elements (12) are oriented substantially in the circumferential direction and may be slightly oblique or have a circumferentially curved shape.

In a variant, not shown, the Cutting wheel (17) in the manner of a whole be formed sintered disc, in which the Support body or disk body and the abrasive coating are integrally connected to each other. The sintered Disk body can become concentric in several divide annular sections that are homogeneous and are integrally connected by sintering. In These ring sections are different material Compositions of the sintered material present.

Modifications of the embodiments shown are in different way possible. Basically, that can Grinding tool (1) with its supporting body (4) and its Abrasive coating (5) have any suitable shape and adapt to a wide variety of purposes to let. The grinding tool (1) can not only be used for cutting or slitting hard materials, but also to Surface removal can be used. The specified Material components can be interchanged or be combined with each other as desired.

LIST OF REFERENCE NUMBERS

1

grinding tool

2

central bore

3

axis of rotation

4

Support body, disk body

5

abrasive coating

6

Joint, weld

7

perforation

8th

additional cutting surface, diamond coating

9

spiral line

10

hard abrasive, diamond, cubic boron nitride

11

undercut

12

grinding element

13

Grinding wheel, hollow granular sphere

14

less hard abrasive, corundum, silicon carbide

15

Binder, matrix for abrasive coating

16

Binder for granular hollow sphere

17

Cut-off wheel, diamond cut-off wheel

18

drill bit

19

saw cable

20

soul

21

feather

22

elastic cladding

23

Cup wheel

24

Sheath, outer surface of the granular hollow sphere

25

abrasive particles

Claims (16)

1. Bonded grinding tool, especially cutting-off tool, containing an abrasive layer (5) with a metallic bonding agent (15) and abrasive materials,

   the sintered abrasive layer (5) containing a mixture of abrasive bodies (13) and abrasive particles (25),

   the abrasive bodies (13) being designed as grain hollow balls,

   the abrasive layer (5) containing one or more types of hard abrasive agent (10) and one or more types of less-hard abrasive agent (14),

   the less-hard abrasive agents (14) being arranged on the outer surface of the grain hollow balls (13), and

   the hard abrasive agents (10) forming the abrasive particles (25).
2. Grinding tool according to Claim 1, characterized in that the grinding tool (1) has a supporting body (4) with an abrasive layer (5) arranged on the circumference or the end face.
3. Grinding tool according to Claim 1 or 2, characterized in that diamond and/or cubic boron nitride are/is contained as hard abrasive agents (10).
4. Grinding tool according to one of the preceding claims, characterized in that corundum and/or silicon carbide are/is contained as less-hard abrasive agents.
5. Grinding tool according to Claim 4, characterized in that the less-hard abrasive agents (14) consist entirely or partly of ceramic corundum.
6. Grinding tool according to one of the preceding claims, characterized in that the difference in hardness between the hard abrasive agent (10) and the less-hard abrasive agent (14) is at least 15 Gpa (HV 1).
7. Grinding tool according to one of the preceding claims, characterized in that the grain hollow balls (13) consist of a ceramic material in which less-hard granular abrasive agents (14) are bonded in place in the outer surface (24) of the grain hollow balls (13) without a further bonding agent.
8. Grinding tool according to one of the preceding claims, characterized in that the body of the grain hollow ball (13) consists of a ceramic material, and the less-hard abrasive agent (14) is connected to the outer surface (24) of the grain hollow ball (13) by means of a ceramic bonding agent (16).
9. Grinding tool according to one of the preceding claims, characterized in that the diameter of the grain hollow ball (13) including the less-hard abrasive agent (14) bonded in place therein is 1 to 10 times the average diameter of the hard abrasive agent (10) or one of the hard abrasive agents (10).
10. Grinding tool according to one of the preceding claims, characterized in that the less-hard granular abrasive agents (14) have a smaller diameter than the hard abrasive agent particles (10, 25).
11. Grinding tool according to one of the preceding claims, characterized in that the abrasive layer (5) is formed by one or more abrasive elements (12) which are connected to the supporting body (4).
12. Grinding tool according to Claim 11, characterized in that the supporting body (4) consists of a material different from the abrasive layer (5).
13. Grinding tool according to one of the preceding claims, characterized in that the abrasive layer (5) is an integral part of a fully or at least partly sintered supporting body (4).
14. Grinding tool according to one of the preceding claims, characterized in that the supporting body (4) has, in addition to the abrasive layer (5), at least one additional cutting layer (8).
15. Grinding tool according to one of the preceding claims, characterized in that the cutting-off tool (1) is designed as a cutting-off wheel (17), as a drill bit (18) or as a flexible sawing cable (19).
16. Grinding tool according to one of the preceding claims, characterized in that the grinding tool (1) is designed as a grinding cup (23).

Images