Fast servo ultraprecise fly cutting machining method for brittleness material complex curved surface

A technology for complex curved surfaces and brittle materials, applied in the field of machining, it can solve the problems of easy cutting damage of brittle materials, and achieve the effect of avoiding brittle cracking, fast and stable cutting, and ensuring surface quality and optical performance.

Active Publication Date: 2017-08-18

TIANJIN UNIV

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Problems solved by technology

The present invention aims at the technical requirements of microstructure curved surface processing and the cutting performance of brittle materials, can solve the difficulty of complex curved surface fo...

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Method used

1. set up processing platform and can realize the flying knife cutting of fast servo motion assistance, fast servo mechanism produces small-sized high-frequency reciprocating motion, cooperates the high-speed rotary cutting of flying knife to realize the single trace removal processing of brittle material.

For the difficult points such as the difficult point of brittle material complex curved surface machining forming accuracy difficulty surface quality is poor, the present invention proposes the processing mode that fast servo combines with flying knife, is about to diamond turning tool vertically installed on the ultra-precision flying knife main shaft, and ...

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Abstract

The invention relates to a fast servo ultraprecise fly cutting machining method for a brittleness material complex curved surface. The method includes the following steps that a machining system with a fast servo mechanism and fly cutting being combined is established; when a machined device is subjected to fly-cutter machining, a cutter is provided with an area nearest to the machined device every time a spindle is rotated once; at the area, due to the fact that the rotating speed of the fly-cutter spindle is unchanged, when the cutter makes contact with the surface of a workpiece, the fast servo mechanism can be used for driving the workpiece to make single-degree-of-freedom high-frequency motion in the cutting-in direction or make multi-degree-of-freedom high-frequency motion in the cutting-in direction and transverse feeding direction so as to be matched with fly-cutter rotation, and an array structure and complex surface can be machined; the proper cutting parameters and cutter geometrical parameters are designed; motion synchronization is achieved by controlling the servo motion and fly-cutter rotation angle, and thus the back cutting depth can be controlled when materials are cut; and finally cutter motion trajectories make fast and smooth traverse motion on the surface of the machined device.

Technology Topic

Single degree of freedomMulti degree of freedom +7

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Examples

Experimental program(1)

Example Embodiment

[0020] Aiming at the difficulty of processing and forming of brittle materials with complex curved surfaces and poor surface quality, the present invention proposes a processing method combining fast servo and flying knife, that is, the diamond turning tool is vertically installed on the ultra-precision flying knife spindle, and the fast servo motion is coupled in linkage. Realize high-speed cutting of complex curved surfaces. This method can realize rapid and high-quality generation of brittle material microstructure arrays and other complex curved surfaces, and avoid impurities and defects that may be introduced in traditional grinding. During processing, the high speed of the fly cutter spindle can be ensured, and the machined surface can be cut with frequency conversion and amplitude through fast servo motion, and the single removal of material during the cutting process can be controlled to achieve high-efficiency and low-damage processing of brittle materials.

[0021] The specific implementation is as follows:

[0022] 1. The construction of the processing platform can realize the flying knife cutting process assisted by fast servo motion. The fast servo mechanism generates small-sized high-frequency reciprocating motion, and cooperates with the high-speed rotary cutting of the flying knife to realize the single micro removal of brittle materials.

[0023] 2. According to the characteristics of the machined surface and the cutting performance of the material, design suitable cutting parameters, including the speed of the fly cutter spindle, the linear feed parameters of the guide rail and the tool geometric parameters;

[0024] 3. Select the appropriate single depth of cut feed, and calculate the frequency and amplitude of the fast servo motion relative to the workpiece depth of cut feed;

[0025] 4. Based on the machining parameters and tool geometric parameters, the machining path generation of servo feed and flying knife cutting is performed, and the tool contour forms the machining surface after traversing the path;

[0026] 5. Install the workpiece to be processed on the processing platform, and the flying knife is installed vertically on the rotary spindle; the workpiece is rotated and intermittently cut, and the height of the machined surface is changed by servo motion. At this time, the cutting direction of the flying knife is perpendicular to the feed direction. After the feed has passed the length of the workpiece, the workpiece of the machine tool guide rail is horizontally translated at an appropriate distance, and the above process is repeated until the complex surface is processed.

[0027] The servo motion mentioned includes two forms: the servo mechanism is placed on the flying knife spindle for servo motion and the fast servo mechanism is placed on the workpiece platform for servo motion. Among them, the fast servo mechanism is placed on the flying knife spindle to perform servo movements such as figure 2 As shown, the fast servo mechanism is placed on the flying tool spindle, and the rotating spindle is parallel to the workpiece platform at this time. During processing, the flying tool rotates while adding high-frequency fast reciprocating motion to cut the workpiece, achieving different vector heights in different positions. Finally, the flying knife passes through the surface of the workpiece until the entire curved surface is processed; the fast servo mechanism is placed on the workpiece platform for servo movement such as image 3 As shown, the fast servo mechanism is placed on the workpiece platform. During processing, the flying knife rotates at high speed while the workpiece performs high-frequency fast reciprocating motion. The workpiece is cut through the relative motion of the two to achieve different vector heights at different positions. The knife passes through the surface of the workpiece until the entire curved surface is processed.

[0028] In the specific embodiment, the processing of 9×9 concave curved surface array is taken as an example, such as Figure 4 As shown, for a single small array surface shape, the realization of its geometric shape is formed by the joint action of the shape of the tool and the rotary motion of the flying knife, and the processing of the same number of arrays will finally form the processing of the entire curved surface. The array surface shape is the superposition of two circular arc profiles. The specific parameters are shown in Table 1. The element surface shape equation is

[0029]

[0030] Table 1 Microstructure array parameters in the embodiment

[0031]

[0032]

[0033] Here we have carried out the relevant calculation of the surface shape, and calculated the frequency and amplitude of the feed of the servo tool relative to the spindle depth direction guide rail to ensure that the lowest point is 1μm from the plane. The specific processing parameters are shown in Table 2.

[0034] Table 2 Processing parameters in the embodiment

[0035]

[0036] The cutting depth can be coordinated with fast servo motion to ensure that the single removal amount is controlled below 60nm, which can be removed within the brittle-plastic transition range of single crystal germanium, and the brittle material is guaranteed to be processed without chipping.

[0037] The calculation of the frequency and amplitude of the servo motion relative to the depth of cut feed of the workpiece mentioned in the specific embodiments refers to the frequency and amplitude of the motion corresponding to the servo motion in combination with the movement of the guide rail when the flying knife rotates a circle. In the case of selecting the appropriate fly cutter spindle speed S and the feed rate F in the depth of the guideway, when the single cutting thickness feed is Δz, if the servo movement displacement z servo Follow the law of sinusoidal vibration, namely

[0038]

[0039] Where A is the amplitude, ν is the frequency, Is the initial phase, and its value is generally 0.

[0040] Therefore, the cutting depth feed per revolution of the fly cutter should be

[0041] Δz=F/S+Asin(2πν/S) (3)

[0042] When the values of F and S are fixed, if you want to use the amplitude of the fast servo motion as much as possible to form the depth of cut feed, you need to couple the servo frequency and the speed of the fly cutter, as can be seen from equation (2),

[0043]

[0044] In order to reduce the number of reciprocating motions as much as possible, n=0, that is, ν=0.25S, so as to increase the cutting depth each time.

[0045] The suitable cutting parameters and tool geometric parameters mentioned in the specific embodiments are: Since the radius of gyration of the flying knife and the tool geometry directly determine the final surface geometric characteristics, the above parameters need to be determined according to the geometric characteristics of the array. On the plane perpendicular to the spindle of rotation, since the radius of curvature of the tip of the array in this direction is 20mm, the radius of gyration of the tool tip must be set to this value. On a plane perpendicular to the cutting direction, the radius of curvature of the array along this direction is 0.5mm, so the selected nose radius is also this value.

[0046] When the flying knife radius of gyration is R and the single cutting feed is Δz, the expression for the actual cutting thickness of the material is

[0047]

[0048] Among them, θ refers to the angular position of the flying knife relative to the rotary spindle, such as Figure 5 Shown.

[0049] It can be found that under suitable cutting parameters, the actual cutting thickness will be much smaller than the cutting depth, thereby realizing low-damage processing of brittle materials.

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Classification and recommendation of technical efficacy words

Avoid brittle
Cutting stability

Fast servo ultraprecise fly cutting machining method for brittleness material complex curved surface

AI-Extracted Technical Summary

Problems solved by technology

Method used

Abstract

Image

Examples

Example Embodiment

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Description & Claims & Application Information

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