阅读说明：本技术 一种回转对称光学表面单点接触超精密车削方法 (Single-point contact ultra-precise turning method for rotationally symmetrical optical surface ) 是由 孙占文 李佩铮 王素娟 杜雪 于 2021-08-23 设计创作，主要内容包括：本发明公开一种回转对称光学表面单点接触超精密车削方法,涉及回转对称光学表面超精密车削技术领域,包括以下步骤：步骤一、安装刀具和工件,刀具固定于Y轴导轨上,工件固定于C轴上；步骤二、确定所加工的工件回转对称表面面型,并建立工件坐标系；步骤三、确定工件回转对称表面的加工轨迹；步骤四、对工件进行车削加工,在车削加工中,工件随C轴的转动而匀速转动,同时刀具随着X轴由工件的外圆周向工件回转中心匀速运动,在X轴匀速运动的同时,B轴做伴随的旋转运动,且Y轴做伴随的伺服运动。本发明解决了回转对称光学表面在超精密车削中由刀尖圆弧半径制造误差所引起的加工面型精度低,且难以提高面型精度的难题。(The invention discloses a single-point contact ultra-precise turning method for a rotationally symmetric optical surface, which relates to the technical field of rotationally symmetric optical surface ultra-precise turning and comprises the following steps: step one, installing a cutter and a workpiece, wherein the cutter is fixed on a Y-axis guide rail, and the workpiece is fixed on a C-axis; secondly, determining the surface type of the rotationally symmetrical surface of the processed workpiece, and establishing a workpiece coordinate system; step three, determining a processing track of the rotation symmetrical surface of the workpiece; and step four, turning the workpiece, wherein in the turning process, the workpiece rotates at a constant speed along with the rotation of the shaft C, the cutter moves at a constant speed along with the shaft X from the outer circle of the workpiece to the rotation center of the workpiece, the shaft B performs accompanying rotary motion while the shaft X performs uniform motion, and the shaft Y performs accompanying servo motion. The invention solves the problems of low precision of the machined surface shape and difficulty in improving the surface shape precision caused by the manufacturing error of the arc radius of the tool nose in the ultra-precision turning of the rotary symmetric optical surface.)

1. A single-point contact ultra-precise turning method for a rotationally symmetric optical surface is characterized by comprising the following steps:

step one, installing a cutter and a workpiece, wherein the cutter is fixed on a Y-axis guide rail, and the workpiece is fixed on a C-axis;

secondly, determining the surface type of the rotationally symmetrical surface of the processed workpiece, and establishing a workpiece coordinate system;

step three, determining a processing track of the rotation symmetrical surface of the workpiece;

and step four, turning the workpiece, wherein in the turning process, the workpiece rotates at a constant speed along with the rotation of the shaft C, the cutter moves at a constant speed along with the shaft X from the outer circle of the workpiece to the rotation center of the workpiece, the shaft B performs accompanying rotary motion while the shaft X performs uniform motion, and the shaft Y performs accompanying servo motion.

2. The turning method of the rotationally symmetric optical surface with single point contact ultra-precision as claimed in claim 1, wherein: the cutter is a diamond cutter.

3. The turning method of the rotationally symmetric optical surface with single point contact ultra-precision as claimed in claim 2, wherein: the cutter has a circular arc-shaped cutting edge.

4. The turning method of the rotationally symmetric optical surface with single point contact ultra-precision as claimed in claim 1, wherein: in the second step, the surface type of the rotationally symmetrical surface of the machined workpiece is determined to comprise a mathematical expression of the surface and the radius of the machined surface;

the mathematical expression for the surface is: y ═ f (x);

the radius of the machined surface is: r _ x.

5. The turning method of the rotationally symmetric optical surface with single-point contact ultra-precision as claimed in claim 4, wherein: in the second step, R _ X is scattered at equal intervals along the X direction by a constant value DeltaL, and the coordinate from the edge of the processed element to the ith point of the gyration center is as follows:

6. the turning method of the rotationally symmetric optical surface with single-point contact ultra-precision as claimed in claim 5, wherein: x (i) and y (i) coordinates corresponding to:

7. the turning method of the rotationally symmetric optical surface with single point contact ultra-precision as claimed in claim 6, wherein: in the third step, the processing track of the rotation symmetrical surface of the workpiece is x (i), y (i),

Technical Field

The invention relates to the technical field of ultra-precise turning of a rotationally symmetric optical surface, in particular to a single-point contact ultra-precise turning method of a rotationally symmetric optical surface.

Background

At present, the rotationally symmetric optical surface is usually processed by a traditional ultra-precise diamond turning method, the precision of the processed surface can reach submicron level, and the surface roughness can reach nanometer level. As shown in fig. 1 and 2, in the ultra-precision turning of a rotationally symmetric optical surface, a workpiece 4 rotates at a constant speed along with the rotation of the C axis, the X axis feeds at a constant speed, and the Y axis moves according to the coordinate position of the X axis, so that a rotationally symmetric spherical or aspheric optical surface is machined.

In the conventional ultra-precision turning, as the diamond tool 5 moves toward the center of rotation of the workpiece 4, the contact point of the diamond tool 5 with the workpiece 4 is constantly changed along the cutting edge of the diamond tool 5, and the surface profile accuracy of the surface to be machined is affected by the manufacturing accuracy of the cutting edge of the diamond tool. The high manufacturing costs and time required to produce a diamond tool cutting edge with high precision result in an expensive price for the diamond tool 5 and in turn in a high manufacturing cost for the rotationally symmetric optical surface elements.

Therefore, it is an urgent need to solve the above-mentioned problems by providing a single-point contact ultra-precision turning method for rotationally symmetric optical surfaces to overcome the above-mentioned disadvantages of the prior art.

Disclosure of Invention

The invention aims to provide a single-point contact ultra-precision turning method for a rotationally symmetric optical surface, which solves the problems that the machined surface precision is low and the surface precision is difficult to improve caused by the manufacturing error of the arc radius of a tool nose in the ultra-precision turning of the rotationally symmetric optical surface.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides a single-point contact ultra-precise turning method for a rotationally symmetric optical surface, which comprises the following steps:

step one, installing a cutter and a workpiece, wherein the cutter is fixed on a Y-axis guide rail, and the workpiece is fixed on a C-axis;

secondly, determining the surface type of the rotationally symmetrical surface of the processed workpiece, and establishing a workpiece coordinate system;

step three, determining a processing track of the rotation symmetrical surface of the workpiece;

and step four, turning the workpiece, wherein in the turning process, the workpiece rotates at a constant speed along with the rotation of the shaft C, the cutter moves at a constant speed along with the shaft X from the outer circle of the workpiece to the rotation center of the workpiece, the shaft B performs accompanying rotary motion while the shaft X performs uniform motion, and the shaft Y performs accompanying servo motion.

Preferably, the tool is a diamond tool.

Preferably, the tool has a circular cutting edge.

Preferably, in the second step, the surface type of the rotationally symmetrical surface of the workpiece to be machined is determined to comprise a mathematical expression of the surface and the radius of the machined surface;

the mathematical expression for the surface is: y ═ f (x);

the radius of the machined surface is: r _ x.

Preferably, in the second step, R _ X is dispersed at equal intervals along the X direction by a constant value Δ L, and the coordinates from the edge of the processed element to the ith point of the rotation center are:

preferably, the x (i) and y (i) coordinates correspond to:

y(i)＝f(x(i))。

preferably, in the third step, the processing track of the rotationally symmetrical surface of the workpiece is x (i), y (i),

compared with the prior art, the invention has the following technical effects:

the invention provides a single-point contact ultra-precision turning method for a rotationally symmetric optical surface, which constantly adjusts the relative angle between a diamond cutter and the processed optical surface through the combined motion of an X axis, a Y axis, a B axis and a C axis, so that the position of the contact point of the diamond cutter and a workpiece on the cutting edge of the diamond cutter is always kept unchanged, the surface shape precision of the processed surface is not influenced by the manufacturing precision of the cutting edge of the diamond cutter, and the purpose of improving the surface shape precision of the processed rotationally symmetric optical surface is achieved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a schematic view of the turning principle of an ultraprecise machining lathe in the prior art;

FIG. 2 is a schematic diagram of a prior art ultra-precision turning process;

FIG. 3 is a schematic view of the turning principle of the ultra-precision machining lathe of the present invention;

FIG. 4 is a schematic view of a single-point contact ultra-precision turning method according to the present invention;

FIG. 5 is a schematic structural diagram of a circular cutting edge of the diamond tool according to the present invention;

description of reference numerals: 1. 2, 3-the position of the arc-shaped cutting edge of the cutter, 4-the workpiece, 5-the diamond cutter, 6-the X-direction guide rail, 7-the Z-direction guide rail, 8-the actual profile of the blade and 9-the least square circular profile of the blade.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide a single-point contact ultra-precision turning method for a rotationally symmetric optical surface, which solves the problems that the machined surface precision is low and the surface precision is difficult to improve caused by the manufacturing error of the arc radius of a tool nose in the ultra-precision turning of the rotationally symmetric optical surface.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

As shown in fig. 3-5, the present invention provides a single-point contact ultra-precision turning method for rotationally symmetric optical surfaces, which is implemented by the combined motion of the X-axis, the Y-axis, the B-axis and the C-axis; the machining principle of this embodiment is shown in fig. 3 to 4, in which a diamond tool 5 is fixed to a Y-axis guide, the diamond tool 5 has a circular cutting edge, and a workpiece 4 is fixed to a C-axis as shown in fig. 3.

In this embodiment, in the turning process, the workpiece 4 rotates at a constant speed along with the rotation of the C axis, and the diamond tool 5 moves at a constant speed along with the X axis from the outer circumference of the workpiece 4 to the workpiece rotation center, so that the movement track of the diamond tool 5 can cover the processing surface of the whole workpiece 4. While the X axis moves at a constant speed, the B axis rotates and the Y axis moves (the servo motion means corresponding motion according to a command, that is, the Y axis moves according to a position point calculated by the formula Y (i) ═ f (X (i)), so that the tool tip (the most pointed end of the diamond cutting edge, which is a fixed point on the cutting edge) of the diamond tool 5 is always in contact with the machining surface, thereby realizing the turning of the rotationally symmetrical surface.

In the embodiment, the contact point of the diamond cutter 5 and the workpiece 4 is always a fixed point on the cutting edge through the accompanying movement of the B axis and the Y axis and is not changed along with the change of the cutting position, so that the influence of the manufacturing error of the cutting edge of the cutter on the surface type precision of the processed surface can be avoided.

In this embodiment, the step of determining the machining trajectory of the rotationally symmetric surface is as follows:

1. according to the machining requirement, firstly, the surface type of the machined rotationally symmetrical surface is determined, the mathematical expression (y ═ f (x)) of the surface and the radius (R _ x) of the machined surface are included, and a workpiece coordinate system is established.

2. And R _ X is dispersed at equal intervals along the X direction by a constant value DeltaL, then the coordinate from the edge of the processed element to the ith point of the gyration center is as follows:

3. in order to ensure that the most point of the arc radius of the diamond tool 5 is always in contact with the workpiece 4, that is, the contact point of the diamond tool 5 and the workpiece 4 is always kept constant on the cutting edge, the B axis and the Y axis need to make accompanying movements, and the coordinates θ (i) and Y (i) corresponding to x (i) can be calculated by the following formula:

y(i)＝f(x(i))。

the processing track of the surface with revolution symmetry, namely x (i), y (i), theta (i) can be obtainedAnd inputting the generated track program into the machine tool, and moving the x axis, the y axis and the B axis according to the instructions to finally machine the ideal rotationally symmetrical surface.

The principle and the implementation mode of the invention are explained by applying a specific example, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.