DD254904A1 - PROCESS FOR MACHINING INSERTION HOLES IN DIAMONDS BY MEANS OF LASER RADIATION - Google Patents

Abstract

The invention relates in particular to the production of conical bores of high surface area by means of laser beams in diamonds for wire drawing. The task is solved by incorporating a complete cone into the diamond whose surface is machined with a laser beam. According to the invention, after drilling, a laser beam with constant power and fixed focus point is centered on the cone base diameter. While the diamond performs a rotationally symmetric and horizontal movement, the lateral surface of the conical bore slides along the laser beam.

Description

Characteristic of the known technical solutions

Methods for processing diamonds, in particular for producing microbores by means of laser beams, are known. The incorporation of conical holes in diamonds is usually designed so that several existing of truncated cones individual holes are extended to a complete cone. Such methods are described in DE-OS 2740755; Industriediamantenrundschau, 4 (1970) 2, pages 91 to 96; 5 (1971) 1, pages 38 to 43 of STRASCHEK.

The characteristic feature of these methods is that the focal point position must be corrected according to the processing depth.

State-of-the-art laser systems for this application are controlled by costly computers, the computer control in particular to allow a coordinated movement in the vertical and horizontal axis and thus produce exact match of focal point position and training depth. These multi-stage laser drilling methods are complicated and complicated.

They are based on the fact that it is done by changing the optical design of the laser system to smaller cone tip diameter.

According to another multi-stage method for processing diamonds by means of laser beams, DD-PS 133023, interlocking, tapered individual bores are introduced at a certain circumference, wherein a center cone remains, which is also shattered by means of laser beams. In this way, a frustoconical bore is introduced to the intended depth.

The decisive disadvantage of the bores produced by these known laser processes is that the surface quality of the lateral surface has too great a roughness and does not fall below a roughness depth of about 0.050 mm.

This is mainly due to the fact that according to the previously practiced method it comes to microscopically fine, paragraph-shaped formations of the lateral surface of the individual incorporated truncated cones or on the circular intermeshing individual bores.

Elaborate polishing processes are therefore necessary to smooth the heels of such holes and make them practical for wire drawing.

Therefore, a fixed focal point method has been proposed for microbores.

Following this procedure, a complete cone is incorporated into the diamond, the base area and height of which are continuously increased to the intended depth.

All previous methods are particularly liable to the disadvantage that they are unsuitable for conical holes with a bore diameter greater than or equal to 0.5mm and a bore depth greater than 1 mm.

One reason is that the layer thicknesses of the material removal must be increased with increasing hole depth.

If this is not done, the processing time would multiply and there is a risk that the bore is asymmetrical

However, the increase in the layer thickness leads to even greater roughness of the mantle surface with a correspondingly high polishing effort.

As a further reason, it can be seen that at a fixed focus point, the laser power must be increased with each processing step to the intended hole depth.

This leads to high energy consumption, so that with continuous wave lasers of low power the maximum laser output power is reached quickly.

If the required laser power is exceeded, a deterioration of the surface quality of the surface due to radiation divergence occurs.

According to a technical article by EDER in Draht 37 (1986) 3, p. 113f., Electroerative methods are therefore now preferred to the laser drilling method, since they lead to a significantly lower roughness.

However, electroerosive processes are only applicable to synthetic polycrystalline diamonds and also very time consuming.

Object of the invention

The aim of the invention is to provide a simple, two-stage, cost-effective method, can be made with the conical holes in diamonds with high Manteloberflächengüte and with the cost of repolishing is reduced to a minimum.

Explanation of the essence of the invention

The object of the invention is to develop a method which ensures the incorporation of conical bores with a cone tip diameter greater than or equal to 0.5 mm, a hole depth greater than 1 mm and a roughness depth of the mantle surface less than 0.005mm in diamonds.

The object is achieved in that a complete cone is incorporated into the diamond and the mantle surface is then processed by the laser.

According to the invention, a laser beam with constant power and fixed focal point is centered on the cone base diameter after drilling, wherein the diamond performs a rotationally symmetric and horizontal movement and the lateral surface of the conical bore slides along the laser beam.

embodiment

The invention will be explained in more detail using an exemplary embodiment.

A synthetic diamond with a height of about 3 mm in a sintered version is centered in a three-point mount.

The input puller is incorporated with a YAG continuous wave laser of lower power.

The laser works with a pulse frequency of 5KHz.

The focal length of the laser lens is 40 mm.

During the cone drilling, the laser output is kept constant at 6 to 8W.

The diamond is moved from outside to inside at a speed of 10 mm min ^-1 , whereby the focus is tracked.

Starting with a bore diameter of 0.20 mm extended to a cone base diameter of 2.5 mm with a bore diameter of 1.5 mm.

The roughness depth after drilling is about 0.050mm.

In a subsequent operation, the lateral surface is processed as follows:

A 10% smaller z value than the baseline value at the particular training depth and an x value 3.33% larger than the x baseline cone diameter baseline are entered into the calculator.

The laser beam is centered on the cone base diameter and the diamond performs a rotationally symmetric and horizontal movement.

With a 12.2% higher laser output than drilling, which remains constant during machining, and a fixed focal point, the surface will slide along the laser beam for a period of 25 to 30 seconds.

The surface roughness of the mantle surface is less than 0.005mm after machining.

Then the starting cone is worked in and polished the die with Feinstpoliermitteln.

Claims (1)

A method of producing high surface area conical bores for wire drawing employing known low power continuous wave lasers, such as a YAG laser, wherein a complete cone is incorporated into the diamond, characterized in that after laser drilling, a constant power laser beam and centering fixed focal point on the cone base diameter, the diamond performs a rotationally symmetric and horizontal movement and the lateral surface of the conical bore slides along the laser beam. Field of application of the invention The invention relates to a method for processing diamonds, in particular for producing conical holes for the wire by means of laser beams.