Disclosure of Invention
In order to solve the technical problems, the invention provides a construction method of a horizontal tool setting error calculation model for ultra-precise turning aiming at a detection method of a tool position error and an influence rule of the detection method on the machining precision of a die. The mathematical model can express the tiny horizontal tool setting error quickly and accurately and correct the tiny horizontal tool setting error, so that the ultra-precision machining and the detection are effectively integrated, and the ultra-precision turning quality and the production efficiency are greatly improved.
The purpose of the invention is realized by the following technical scheme:
a method for constructing a horizontal tool setting error calculation model for ultra-precise turning comprises the following steps:
step one, machining a part, wherein the measured value of the tool nose at the horizontal distance from the rotation center of the workpiece is x1The actual value is x2The horizontal tool setting error x' is expressed by the following formula:
x′=x1-x2;
step two, obtaining an ideal outline of a great circle of the detected region according to the structural characteristics of the surface type of the curved surface of the part, wherein the radius value is R, and the quarter central angle of the ideal outline is recorded as w1The radius value of the actual detection range of the mold in the vertical projection direction is recorded as b, and the parameter R, w1And b has the following relationship:
parameter R, w1And x1There is the following relationship between:
thirdly, using a Zygo-ZeGage contourgraph to perform surface type fitting on the surface type of the curved surface of the part to obtain the spherical diameter r of the detected region of the surface type of the curved surface of the part, and recording the quarter central angle of the actual contour corresponding to the fitting circumference as w2Parameters r, w2And x2There is the following relationship between:
step four, according to the data obtained in the step one, the step two and the step three, establishing a mathematical calculation model of the horizontal tool setting error x' and the sphere diameter detection value r as follows:
the calculation model constructed by the method can be applied to the technical field of precision manufacturing, and when the calculation model is used for correcting the horizontal tool setting error, the method comprises the following steps:
firstly, processing by using an ultra-precise slow-tool servo lathe to obtain a part;
secondly, performing surface type fitting on the machining surface of the part by using a Zygo-ZeGage contourgraph to obtain the sphere diameter r of the detected region, and establishing a mathematical calculation model of a horizontal tool setting error x' and a sphere diameter detection value r;
and step three, quickly determining the tool setting error in the horizontal direction through the detection result, and thus accurately correcting.
Compared with the prior art, the invention has the following advantages:
1. the mathematical model of the horizontal tool setting error can accurately calculate the tiny tool setting error x' through the surface type detection data by means of the Zygo contourgraph.
2. The tool setting error mathematical model effectively integrates the processes of ultra-precision machining, surface shape detection and error correction of the die, and greatly improves the ultra-precision machining quality and the production efficiency of the die.
3. The tool setting error mathematical model is verified by actual ultra-precision machining, and has actual industrial application value and theoretical significance for the ultra-precision machining of other similar products.
Detailed Description
The technical solution of the present invention is further described below with reference to the accompanying drawings, but not limited thereto, and any modification or equivalent replacement of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention shall be covered by the protection scope of the present invention.
The invention provides a method for constructing a horizontal tool setting error calculation model for ultra-precise turning, which comprises the steps of obtaining a part by utilizing an ultra-precise slow tool servo lathe, carrying out surface type fitting on the processing surface of the part by using a Zygo-ZeGage contourgraph to obtain the spherical diameter r of a detected area, establishing a mathematical calculation model of a horizontal tool setting error x 'relative to the spherical diameter detection value r, determining the tool setting error x' value in the horizontal direction according to the detection result speed, and accurately correcting processing parameters. The method specifically comprises the following steps:
step one, machining a part, wherein the measured value of the tool nose at the horizontal distance from the rotation center of the workpiece is x1The actual value is x2The horizontal tool setting error x' can be expressed by the following formula:
x′=x1-x2。
step two, obtaining an ideal contour of a great circle of the detected region according to the structural characteristics of the surface type of the curved surface of the part, wherein the radius value is R, and the central angle of a quarter of the ideal contour is recorded as w as shown in FIG. 21The radius value of the actual detection range of the mold in the vertical projection direction is recorded as b, and the parameter R, w1And b has the following relationship:
parameter R, w1And x1There is the following relationship between:
thirdly, using a Zygo-ZeGage contourgraph to perform surface type fitting on the surface type of the curved surface of the part to obtain the spherical diameter r of the detected region of the surface type of the curved surface of the part, and recording the quarter central angle of the actual contour corresponding to the fitting circumference as w2Parameters r, w2And x2There is the following relationship between:
step four, the change of the part curved surface shape in the horizontal direction is very small, namely x' is very small, and w1≈w2According to the data obtained in the above steps, a mathematical calculation model of the horizontal tool setting error x' and the sphere diameter detection value r is established as follows:
further, by utilizing the established mathematical relation model between the horizontal tool setting error x 'and the spherical diameter detection value R, when R is less than R, x' is greater than 0, and the cutter is over-cut; when R is more than R, x' is less than 0, and machining residue exists in the center of the workpiece.
Further, the actual detection process usually adopts a large sphere diameter and small area detection mode, w1Very small value, 2sinw in the above formula1×cosw1=sin2w1< 1, so:
R-r>>x′;
namely, the difference value between the standard sphere diameter R of the detected workpiece and the detected sphere diameter R is the amplified embodiment of the horizontal tool setting error x ', and is easier to detect, so that the derived x' is more accurate.
Furthermore, the mathematical relation model between the horizontal tool setting error x' and the spherical diameter detection value r established according to the method corrects the horizontal tool setting error, and further detects the contact lens metal mold, so that the ultra-precision machining quality and the production efficiency are improved.
In the invention, the material of the parts is mainly nonferrous metals such as copper, aluminum and the like.
In the invention, the selected equipment for processing parts is an ultra-precise single-point diamond lathe.
In the invention, the motion control precision of the ultra-precise single-point diamond lathe is in a nanometer level, and the influence on the processing precision can be completely ignored.
In the invention, the optical cutter measuring system of the ultra-precise single-point diamond lathe can also realize repeated measurement within +/-2 mu m of the radius of the circular arc of the cutter tip, and the dimensional precision of the cutter is eliminated through detection and compensation.
Example (b):
and respectively selecting myopia lens molds of 0 degree, 550 degrees and 900 degrees as processing and detection objects, using a 20-time optical lens of Zygo, and setting the radius value b of the vertical projection direction of the detection range to be 0.8mm by the lens in an image splicing mode.
The ideal radii of curvature of the central arcs of the three molds are 7.63mm, 8.55mm and 9.42mm, and the correctness of the model is verified by performing processing and detection tests with the obtained mathematical model as a guide, and the results are shown in table 1.
TABLE 1 test results
From the results in table 1, it can be seen that the calculation model of the present invention, combined with the precise detection function of the Zygo profiler, can show the horizontal tool setting error x' by a factor of approximately 10 through the (R-R) value, so as to provide support for more precise tool position determination. The mathematical model of the invention can quickly and accurately correct the tool setting error, effectively combine the ultra-precision processing and detection of the contact lens mould, obtain stable and reliable ideal products, and greatly improve the processing quality and efficiency.