SU1161347A1 - Method of machining optical surfaces - Google Patents

Abstract

THE METHOD FOR TREATING OPTICAL SURFACES, in which the tool in one cycle is reported a planetary motion and is moved relative to the part along a predetermined path, which is different in that the number of passes along a predetermined path is chosen integer and even, and in the second half of the cycle the direction the planetary motion of the instrument is reversed, and the ratio of the velocities of the transference motion of the center of the instrument and the displacement along its path is chosen from the condition Vi: Vz 80: l. W (L O) with 4

Description

The invention relates to the production of optical parts, in particular, to the processing technology of large mirrors and lenses with high-precision flat, spherical and aspherical surfaces and can be used in the software processing of optical blanks.

The purpose of the invention is to improve the processing accuracy by compensating for the initial non-uniformity of material removal with additional non-uniformity leading to smoothing of the total removal at each elementary segment.

FIG. 1 shows the scheme of implementation of the proposed method; in fig. 2 is a plot of material removal along the path for different values of the Vi: V2 ratio.

The tool 1 with a diameter d performs planetary motion, which consists of forced rotations about the axis OiOi with frequency n and relative to the axis OjO located parallel to the axis Oi.Oi at a distance e from it, with frequency n. 0 of the tool, and Ya is the linear speed of movement of the secondary center Og of the tool along a predetermined path over the surface of the workpiece 2. The ratio of the rotational frequencies HI, as well as e: d, is selected from the interval of optimal values obtained as a result of sequencers to process mathematical model and experimental treatment surfaces by means of the planetary gear. Force closure is produced by applying force to an instrument.

The method is carried out as follows.

According to the results of controlling the shape of the surface of the workpiece, the tool path is chosen along which the axis Og Og moves. If the shape error of the original surface of the workpiece has an axisymmetric structure, then the motion path may, for example, be concentric circles. In general, the motion path is an arbitrary curve. For surface treatment along the selected path, it is necessary that in one full pass the axis of rotation moves from the starting point of the path to the end point. Otherwise, not the entire surface of the workpiece along the selected trajectory will be processed for an incomplete pass. Therefore, the number of passes along a given trajectory must necessarily be an integer. The total number of passes in one cycle is divided into two equal whole parts.

so that the uneven removal of material that occurred during the first half of the machining cycle was compensated for by the uneven removal of material that occurred during the second half of the machining cycle, with a changed direction of rotation of the tool around the OiOi and OOg axes. Since the number of passes in the first half of the cycle is chosen equal to the number of passes in the second half of the cycle, while the other processing modes remain constant, the uneven material removal rates for both half cycles are equal, the material removal asymmetry along the processing path is absent and surface quality is improved.

The movement of the tool along the selected trajectory should be carried out at a speed YE at least 80 times less than the speed Vj of the moving movement of the tool. In this case, the magnitude of the waviness of the residual surface profile along the trajectory will not exceed 2%, which guarantees high quality processing.

After the treatment cycle has been completed, the surface is monitored, a new treatment program is determined, the selected tool path and the number of passes along it may differ from those in the previous cycle, but all other processing conditions must be preserved.

0 To illustrate the proposed method, two parts were machined with spherical optical surfaces of radius R 2200 mm and diameter D 400 mm made of optical glass K-8. Before the beginning of treatment, both parts were checked on a Newton interferometer such as the Newton interferometer and the technological processing modes were determined.

For part number 1: ni. 160 rpm; 0 g 80 rpm; e 20 mm; d 40 mm; Р 6Н; Vi 170 mm / s; Va 2 mm / s. Trajectories of movement - concentric circles with radii R.

The number of passes K along trajectories is presented in table. 1. 5 For part No. 2: n 160 rpm; p -80 rpm; e 20 mm; d 40 mm; Р6Н; Yi 170 mm / s; mm / s

The motion paths are concentric circles with radii ja. - The number of passes K along trajectories is presented in table. 2

After that, for part No. 2, the direction of rotation relative to the axes Oi, Oi and Ogog is reversed: n 160 rpm, Pa 80 rpm, and the second processing stage is carried out with the same number of passes as in the first stage. The remaining parameters did not change. The quality of the surface of the workpiece number 2 is higher, therefore, the separation

the processing cycle into two parts equal in time and in an integer number of passes along the selected trajectory, when the direction of rotation n is changed, and n on the reverse during the second part of the cycle, the processing accuracy is improved.

Table 1

Relates, eat Fig.g Relates, length C .A trajectory

Claims (1)

METHOD OF OPTICAL SURFACES PROCESSING, in which the tool is informed of a planetary motion in one cycle and moved relative to the part along a predetermined path, characterized in that, in order to increase the accuracy of processing, the number of passes along a given path is chosen integer and even, and in the second half of the cycle the direction of planetary movement of the tool is reversed, while the ratio of the speeds of the portable movement of the center of the tool and the movement along its path is chosen from the condition V _t : Y _g > 80: 1. FIG. 1 SU ,, 1161347