SU1636195A1 - Method of vibratory plane-parallel lapping - Google Patents

Abstract

The invention relates to abrasive machining and can be used for two-sided finishing of single-crystal thin and brittle plates used in the electronics industry, as well as precision parts in machine building and instrument making. The aim of the invention is to improve the quality of refinement by forming an optimal microrelief with a uniform distribution of irregularities across the range of steps. For this, the direction of rotation of the carrier is reversed after each revolution. At the same time, the forward circular antiphase movements of the lapping discs are reversed and their amplitude is measured by an amount that depends on the number of revolutions of the carrier per treatment cycle, the radius during: diol, the average amplitude of the progressive circular motions of the lapping disks and the frequency of their circular movements. In addition, each abrasive grain can pass only along an equidistant complex trajectory, forming a micro-relief with a uniform distribution of irregularities along the spectrum of steps. cl

Description

The invention relates to abrasive machining and can be used for two-sided finishing of single-crystal thin and brittle plates used in the electronics industry.

The aim of the invention is to improve the quality of fine plate adjustment by forming an optimal microrelief with a uniform distribution of irregularities across the spectrum of steps.

The property of the treated surface depends not only on the size of the roughness, defined by the Ra parameter, but also on the shape of asperities, which is characterized by the spectral composition of the microrelief. By optimal is meant a microrelief that has the smallest height of micro unevenness, in the absence of separate cavities and protrusions and the most uniform distribution of irregularities along the spectrum of steps.

The method is carried out as follows.

Plates subject to vibratory plane-parallel adjustment are placed in a carrier between lapping discs. By switching on the electromagnetic vibration exciter, the lapping disks are informed by forward circular antiphase movements, and the carrier and the plates - by the rotational movement around the center of their axes.

After one turn of the carrier, the direction of its rotation is changed, and at the same time the reverse circular translational

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phase movements of the lapping discs and change the amplitude of the translational circular motions by the value of YES, determined from the condition:

D. Amaks Amin

P

where Amaks and A min is the range of amplitudes of effective processing,

n is the number of revolutions of the carrier, determined by the formula

n -, t

where T is the duration of the processing cycle,

t - time of one revolution drove.

When moving parts together with the carrier, each abrasive grain will leave a trace on the part in the form of a spiral with a width equal to two amplitudes of vibrations. During one turn of the carrier, the parts will have a grid of spirals of the same width, but formed by different abrasive grains,

The probability of the complete superposition of any spiral traces in this case is close to zero. In the second revolution of the carrier, there is a probability that the abrasive grains fall into their bleda, and, consequently, the formation of deeper depressions. If, during the second revolution, the amplitude of oscillations is reduced, then all the grains will describe equidistant trajectories with a spiral wake of smaller width, and the probability of coincidence of their own wakes will be zero.

When reversing vibrations of the grinding discs, after each turn, the cutting edges of each abrasive grain enter into the cutting work, which contributes to the self-sharpening of the grains and completely eliminates the coincidence of any traces. Thus, a microrelief will be formed with a uniformly distributed spectrum and extremely low smoothed irregularities.

For example, if the processing cycle T is 5 rotations of the carrier, and the range of amplitudes of the effective processing is within 0.5–5 mm, then the change in the amplitude of the translational circular motions of the disks per revolution of the carrier is:

Amaks AMIN 5 - 0.5

p5

In the case when the rotation of the carrier is carried out from oscillations of the lapping disk, the time of one revolution of the carrier t is determined from the condition

t

YES

0.9 mm.

4 (Amaks Amin). (Aiah

0-v

where R is the radius of the carrier; v- frequency of circular movements of the disks

Amaks - AMIN

- - The average amplitude of the translational circular movements of the grinding wheels.

For example, the radius of the carrier R is 250 mm, the maximum amplitude of circular movements of Amax disks is 5 mm, the minimum AMin is 0.5 mm, the frequency of circular movements of disks is V-25 Hz, then the time t of one revolution of the carrier is 7 seconds.

If the processing cycle is T 2 min, then the change in the amplitude YES of the translational circular motions of the disks in one revolution of the carrier is 0.26 mm.

In the case of diamond finishing of single crystal plates by the proposed method, the grain is exposed to forces that change rapidly in time and direction, which prevents the formation of deep scratches on the plate, since the grains will not be able to stay in a fixed state for a long time. Since each grain of abrasive can pass only along an equidistant complex trajectory, an optimal microrelief is formed on the surface of the plates with a uniform distribution of irregularities along the spectrum of steps.

The productivity of the process is somewhat lower due to a partial decrease in the amplitudes of the oscillations, but this decrease significantly overlaps with an increase in the surface quality achieved.

Claims (1)

Invention Formula The method of vibrating plane-parallel fine-tuning of thin plates, in which they are placed in a rotating carrier between lapping discs, performing translational circular antiphase movements, characterized in that the direction of the rotational movement of the carrier is improved after each rotation, it is reversed, at the same time the progressive circular antiphase movements of lapping are reversed. disks and change their amplitude by an amount YES determined by the formula YES where Amaks and Amin is the range of processing amplitudes; p - the number of revolutions drove