RU2234415C2 - Method of turning of superhard materials - Google Patents

Abstract

FIELD: working of superhard materials.

SUBSTANCE: the invention is pertinent to the method of working of the superhard materials such as diamonds, boron nitride and composites on their basis. The method provides for working of a surface of a rotated preform by a diamond cutter, its grinding by a diamond grinding wheel rotating in a direction counter to the direction of rotation of the perform caused by diamond grinding wheel, on the surface of which the preform makes a reciprocal motion in respect to the axis of rotation of the diamond grinding wheel. The surface of the diamond grinding wheel is treated with a water solution with рН = 3 - 10, and the perform they additionally grind rigidly fixing it relatively to the axis of rotation of the diamond grinding wheel and reversing the direction of its rotation for opposite one. The invention allows to improve the quality of working.

EFFECT: the invention allows to improve the quality of working.

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Description

The invention relates to the field of processing technology of superhard materials: diamond, boron nitride, as well as composites based on them, and can be used in the diamond processing industry.

A known method of turning superhard materials, in particular diamond, which consists in processing the surface of a rotating workpiece with a diamond cutter, which moves reciprocally along the surface to be machined [1].

The disadvantage of this method is the low quality of the processed surface, on which a rough, rough relief is formed with microcracks extending into the depth of the workpiece (crystal).

The closest set of essential features to the proposed one is the method of turning superhard materials, in particular diamond, which consists in treating the surface of a rotating workpiece with a diamond cutter, and then grinding it with a diamond wheel that rotates in the opposite direction of rotation of the workpiece, and on the surface of which the workpiece moves reciprocally relative to the axis of rotation of the circle. The surface of the circle is electrochemically treated in an electrolyte solution [2].

The disadvantage of this method is the low quality of the treated surface. When processing the surface of a workpiece of superhard material, for example natural diamond, with a diamond cutter, a coarse-grained relief is formed on the surface with microcracks extending into the depth of the crystal. Subsequent grinding of the workpiece with a diamond wheel reduces surface roughness. However, when processing a workpiece with a diamond wheel, the coarse-grained relief cannot be completely eliminated, even with additional electrochemical treatment of the surface of the wheel. This is due to the fact that the electrochemical treatment leads to uneven dissolution of the ligament. Worn (dull) grain tops glide along the surface to be treated, and the grain top, which quickly emerges from the binder in an area with an increased dissolution rate, penetrates the surface of the workpiece and forms an expanding and deepening scratch on its surface. This leads to the formation of depressions and the formation of a coarse-grained relief.

The objective of the invention is to improve the quality of processing (turning) of superhard materials.

The problem is achieved in that in the proposed method of turning superhard materials, which includes surface treatment of a rotating workpiece with a diamond cutter and its subsequent grinding by rotating in the direction opposite to the rotation of the workpiece with a diamond wheel, the surface of which is processed in an aqueous solution, with the reciprocating movement of the workpiece relative to the axis the rotation of the diamond wheel, the workpiece is additionally ground when it is rigidly fixed relative to the axis of rotation of the diamond wheel and enii direction of rotation is reversed, while for processing wheel surface, an aqueous solution of pH 3-10.

During processing with a diamond wheel, the surface of which is processed in an aqueous solution with a pH of 3-10, the dissolution of the binder occurs more evenly (due to the lack of passivation of the surface). As a result, the process of exposure of grains from the bundle occurs at close speeds, the load on the grains is the same, which contributes to the formation of a relief more uniform in roughness. Subsequent fixing of the workpiece relative to the axis of rotation of the circle and changing the direction of rotation of the circle (to the opposite) reduce and even out the load on the grains and contribute to the formation of a homogeneous, less rough relief with a small number of small microcracks extending into the depth of the crystal. Thus, a technical result is achieved, which consists in improving the quality of the processed surface. In particular, the diamond blank on the belt has no metals, the surface quality of the girdle of the future diamond is improved, and color characteristics are improved.

It should be noted that an increase in pH of more than 10 reduces the rate of dissolution of the ligament and leads to the formation of a coarse-grained relief. A decrease in the pH value of less than 3 leads to a sharp increase in the rate of dissolution of the ligament and the appearance of many sharp peaks on its surface. As a result, the surface roughness increases.

The proposed method is as follows.

The diamond workpiece is fixed in the mandrel and pre-treated with a diamond cutter at a workpiece rotation speed of 3000 rpm. After removing the protrusions, the surface of the workpiece is ground with a diamond wheel rotating at a speed of 300 rpm in the direction opposite to the rotation of the workpiece, and the workpiece is reciprocated along the surface of the circle. To uniformly dissolve the binder, the surface of the diamond wheel is treated in an aqueous solution with a pH of 3-10. The required pH value is created by adding sodium tetraborate (pH 7-10) or hydrochloric acid (pH 3-7) into the solution. To form a less rough relief of the diamond workpiece, additional grinding is performed. To do this, the workpiece is rigidly fixed relative to the axis of rotation of the diamond wheel, the surface of which is treated with an aqueous solution with a pH of 3-10, and the direction of rotation of the wheel is reversed.

According to the proposed method, 5 crystals of diamond weighing 0.3 carats were turned. The surface roughness of the processed billets (diamonds) is presented in the table.

When processing the crystal by a known method (prototype), the surface roughness was 0.6 μm, which is 2 times higher than by the proposed method.

Sources of information

1. V.I. Epifanov, A.E. Pesina, L.V. Zykov. Technology for processing diamonds into diamonds. - M.: Higher School, 1987, p.132-152.

2. V.I. Epifanov, A.E. Pesina, L.V. Zykov. Technology for processing diamonds into diamonds. - M .: Higher school, 1987, p.165 (prototype).

Claims (1)

A method of turning superhard materials, including diamond, comprising surface treatment of a rotating workpiece with a diamond cutter and its subsequent grinding with a diamond wheel rotating in the opposite direction to the workpiece rotation, the surface of which is processed in an aqueous solution, with the reciprocating movement of the workpiece relative to the axis of rotation of the diamond wheel, characterized in that the workpiece is additionally ground with its rigid fixing relative to the axis of rotation of the diamond wheel and changing its direction rashchenija reversed, and for processing wheel surface, an aqueous solution of pH 3-10.