FI76273B - Metallic, copper-based binding agent for producing a work surface for a honing tool - Google Patents

Abstract

This invention refers to the production of a honing tool, that is intended to be used for working natural building materials and other non-metallic materials which are inconvenient to machine, and more accurately this invention is about making a copper-based metallic binding agent meant for producing a work surface for a honing tool. This metallic binding agent consists of the following components (percentage by weight): tin 13-17, cobalt 2-9, 9, titanium hydride 7-10 and lanthanum hexaboride 0.01-0.09, while the remainder is copper.

Description

1 76273

Copper-based metallic binder for making the work surface of an abrasive tool

The invention relates to the manufacture of abrasive tools used for machining natural building materials and other difficult-to-machine non-metallic materials, and more particularly to metallic copper-based binders for the manufacture of abrasive tool worktops.

A metallic copper-based binder for the manufacture of a work surface for an abrasive tool is known (SU-A-985 111), which consists of the following components (in weight percent): tin 8-12 iron 8.5-12 cobalt 13-28 titanium boride or binary titanium chromium boride and t -anohydride mixture in corresponding weight ratios 1-2: 1 4.5-24 copper the rest The abrasive tool work surface based on this metallic binder has poor wear resistance when the tool is used at higher than normal working power. Thus, for example, the wear resistance of a 320 mm diameter diamond saw surface when cutting granite at a saw feed speed of 1000 mm / min. is 2 7.4 m granite, and the consumption of synthetic, 2 diamonds with a grain size of 400/315 is 3.2 carats / m granite.

The object of the invention is to find a metallic copper-based binder which would improve the wear resistance of the work surface of an abrasive tool when the tool is used with a higher than normal working power 2 76273

The object is solved by providing a metallic copper-based binder containing tin, cobalt, titanium hydride and, according to the invention, in addition lanthanum hexaboride for the production of the work surface of an abrasive tool, the proportions of the components being as follows (% by weight): tin 13-17 cobalt 2-9.9 titanium hydride 7-10 0.01-0.09 copper rest

By incorporating lanthanum hexaboride into the metallic binder according to the invention, the working surface of the abrasive tool is made fine-grained, which in turn improves the strength properties of the working surface and thus also the wear resistance. Thus, for example, the bending strength of a work surface obtained using a metallic binder according to the invention at 60 ° C is 60 kp / mm 2 and at 500 ° C 47 kp / mm 2, which is 1.8 times higher than the bending breaking strength of a work surface based on a known metallic binder. In addition, the wear resistance of the working surface of the diamond saw obtained by using the metal binder according to the invention (saw diameter 320 mm) when cutting granite at a saw feed speed of 2,100 mm / min. rises to 25.1 m of granite, which is three times the wear resistance of the work surface of a diamond saw based on a known binder, and the consumption of 2 diamonds with a grain size of 400/315 does not exceed 1.47 carats / m of granite.

As mentioned above, the metallic binder according to the invention contains 13 to 17% by weight of tin. If the amount of tin in the binder is reduced to less than 13% by weight, the porosity of the working surface of the abrasive tool increases, as a result of which the strength of the surface and consequently also the wear resistance deteriorates. On the other hand, if the amount of tin in the binder exceeds 17% by weight, more brittle chemical compounds are formed in the manufacturing process of the work surface of the abrasive tool, which again results in deteriorated wear resistance.

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If the metallic binder according to the invention contains less than 2% by weight of cobalt, the shrinkage of the work surface during the manufacturing process increases. If the amount of cobalt is increased to more than 9.9% by weight, the sintering temperature of the binder in the manufacture of the work surface of the abrasive tool increases, which adversely affects the strength of the diamond grains.

If less than 7% by weight of titanium hydride is included in the metallic binder according to the invention, the diamond granules adhere less well to the working surface of the grinding tool, which results in the deterioration of the wear resistance of the work surface. On the other hand, if the titanium hydride is more than 10% by weight, the work surface shrinks and cracks form during the manufacturing process.

If less than 0.01% by weight or more than 0.09% by weight of lanthanum hexaboride is included in the metallic binder according to the invention, the work surface of the abrasive tool is not made fine-grained, which impairs the strength properties and abrasion resistance of the work surface.

The incorporation of copper in the metallic binder according to the invention to said extent guarantees the required physical and mechanical properties of the work surface of the abrasive tool to be manufactured.

The copper-based metallic binder according to the invention is prepared by mixing its powdered ingredients in a mixer in said proportions.

In order to produce the work surface of the abrasive tool based on the binder thus obtained, granules of the abrasive material are added to the binder. The granules of the abrasive material may be included simultaneously with the mixing of the binder ingredients. As the abrasive material, for example, diamond, cubic boron nitride, boron carbide, tungsten carbide, titanium carbide or a mixture thereof can be used. The amount of abrasive material is usually 5-40% by weight of the metallic binder. The resulting mixture of metallic binder and abrasive material is treated by methods known in powder metallurgy, such as compression molding at a compression pressure of 5000-2 4 76273 7000 kg / cm, after which the compression is removed from the compression mold and sintered at 870-1000 ° C under vacuum for 30-60 min. The resulting abrasive tool work surface is then cooled, machined, and attached to the abrasive tool body.

The following Table 1 shows the different compositions of the metallic binder according to the invention as well as the composition of the known (SU-A-985 111) metallic binder.

table 1

Metallic _Amount of ingredients,% by weight _ binder Lanthanum-Titanium composition- Titanium-hexadiboride its No. Tin Cobalt hydride boride Copper Iron hydride * 1 mixture (weight percentage _ _ _ _ __ _____ _ ratio 1: 1) I 16 .9 9.9 7 0.01 67 II 13 2.91 10 0.09 74 III 17 2 8 0.05 72.95

IV

(SU-A-985 111) 8 27 - - 40 12 13

Using a metallic binder according to the invention (compositions I-III) and a known metallic binder (composition IV), work surfaces of a tomato saw (saw diameter 320 mm) were prepared. All of the above binders were mixed with synthetic diamonds having a grain size of 400/315 so that the amount of diamonds was 7.5% by weight of the metallic binder. The resulting mixtures were extruded in a compression mold at a pressure of 6000 kg / cm, after which extrudates consisting of segments with a length of 40 mm, a width of 4 mm, a height of 6 mm and a radius of 160 mm were removed from the compression mold and sintered in a vacuum oven at 980 ° C for 40 min. . The resulting work surface segments were cooled, machined and attached to the frame of steel saws. The diameter of the saws was 320 mm.

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The saws to which the work surfaces were attached were tested by cutting granite with a milling machine under the following machining conditions: saw feed speed 1000 mm / min, saw circumferential speed 20.9 m / s, saw depth with one stroke 30 mm, water cooling, water consumption 8-10 1 / min. The results of the experiments are summarized in Table 2.

Table 2

Wear resistance of the binder on the work surface of a metallic saw, wear of diamonds, composition m ^ granite carat / rn granite its No. I 16.1 1.47 II 20.3 1.15 III 25.1 0.94

IV

(SU-A-985 111) 7.4 3.20

As can be seen from Table 2, the wear resistance of the saw surfaces based on the metallic binder according to the invention (compositions I-III) exceeds the wear resistance of the working surface based on the known metallic binder (composition IV) 2-3 times. The consumption of diamonds on work surfaces based on the binder according to the invention is 2-3 times lower than the consumption of diamonds on a work surface based on a known binder.

Saws to which a work surface based on the binder according to the invention was attached (compositions I-III) were otherwise tested under the same conditions as above, but at a saw feed speed of 1250 mm / min. The results are summarized in Table 3.

Table 3

Metallic bond- Saw work surface Composition resistance of the material on the work surface, the expansion of diamonds (^ a its No. _ nr granite ara ia / m Grann I 13.2 1.76 II 13.0 1.78 III 15.0 1, 56 6 76273

By means of the binder according to the invention, it is thus possible to produce a work surface of an abrasive tool which is characterized by even better wear resistance when the tool is used at a higher working power than usual.

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