CN108856918B - Electric spark machining method for array type fine stepped groove - Google Patents

Abstract

The invention relates to an electric spark machining method for array-type fine stepped grooves. The method first prepares micro-array electrodes with different sizes and patterns, and then uses the micro-array electrodes with different sizes and patterns to perform EDM machining on a workpiece with different depths to form micro-array stepped grooves. The number of steps of the stepped groove is greater than or equal to 2, and the number of different patterns corresponds to the number of steps of the stepped groove. Further, electrode wear compensation can be performed by adding fine array electrodes with identical patterns. The invention can complete the processing of the N (N≥2) order micro stepped grooves of the array by the fine electric spark technology, and can ensure the verticality of the stepped grooves by compensating for electrode loss.

Description

An EDM method for arrayed micro-stepped grooves

technical field

The invention relates to the technical field of micro electric discharge machining, and more particularly to a 2.5D electric discharge machining method of array type micro stepped grooves.

Background technique

The micro-EDM technology uses the pulsed spark discharge between the workpiece and the tool electrode to generate instantaneous high temperature to locally melt and vaporize the workpiece material, so as to achieve the purpose of erosion processing. Due to the characteristics of non-contact processing, almost no cutting force, and no limitation of material strength and hardness, micro-EDM technology is especially suitable for high-precision, non-deformation micro-part feature processing and micro-processing of hard, brittle, and difficult-to-machine conductive materials. Therefore, micro-EDM technology has become an important direction in the field of micro-manufacturing, and is more and more widely used in the processing of key parts in aerospace, electronic information, molds, and optical and medical devices.

The traditional single-electrode serial machining method of micro-EDM is very inefficient, and its consistency is difficult to guarantee, resulting in limited machining accuracy. In response to this problem, several micro-EDM batch processing technologies have been proposed, including the fabrication of square electrodes by EDM, the LIGA process by photolithography, and the fabrication of array electrodes of any shape by metal etching. However, because these methods are two-dimensional array graphics processing technology by controlling the processing depth, the shape and structure of the processing are greatly limited.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention proposes a 2.5D EDM method for arrayed micro stepped grooves. The method uses micro electrodes with different patterns to process the workpiece with different depths, and can form stepped grooves with different depths on the workpiece. The reason why the present invention is called "2.5D" is that it can process a structure between 2D plane graphics and 3D three-dimensional graphics, that is, by stacking 2D graphics structures of different depths and different sizes to form 2.5D graphics with a certain three-dimensional structure structure.

The invention discloses a 2.5D electric spark machining method for arrayed micro stepped grooves. First, micro array electrodes with different sizes and patterns are prepared, and then the micro array electrodes with different sizes and patterns are respectively used to carry out EDM machining of workpieces with different depths. , forming a micro-array of stepped grooves.

Further, the position, size and positioning structure of the micro-array electrodes of different sizes and patterns are designed, and the electric spark cutting process (manufacturing square electrodes), the LIGA process using photolithography technology, the electroforming process and the metal etching process are used. process and other methods to complete the fabrication of micro-array electrodes. Further, the positioning structure is a fine positioning structure added when manufacturing electrode array patterns, such as straight lines, squares, dots, circles, etc. This structure plays a positioning role in electrode loss compensation and stepped processing.

Further, the materials of the fine array electrodes include copper and its alloys, nickel and its alloys, graphite and its compounds, tungsten and its alloys, and other spark electrode materials.

Further, the number of steps of the stepped groove is not limited, and the number is greater than or equal to 2; the number of the shapes of different sizes corresponds to the number of steps of the stepped groove, and the number is also not limited.

Further, in the micro-array electrodes, the electrode loss compensation is performed by adding array electrodes with the same pattern in the same pattern, and the number of array electrodes used for electrode loss compensation is not limited, and the number is greater than or equal to 2. In the process of EDM, not only the workpiece material is eroded due to high temperature, but also the tool electrode is lost, especially the loss at the corner of the electrode is obvious, showing a certain rounded corner, which is called electrode loss. Electrode loss compensation refers to the multi-electrode machining correction, which can minimize the existence of the workpiece rounded corners and improve the machining accuracy.

Further, the formation method of the stepped groove, according to the inclusion relationship of different graphic sizes, also has differences in its processing order, which is divided into three types, taking the second order as an example:

a) First process the small graphic structure with a deep processing depth, and then process the large graphic structure with a shallow processing depth;

b) First, the large graphic structure is processed, and the processing depth is shallow, and then the small graphic structure is processed, and the processing depth is deep;

c) First, the small pattern structure is processed, and the processing depth is deep, and then the large pattern structure is processed, and the processing depth is shallow. There is no electrode structure in the overlapping part of the large pattern and the small pattern, that is, no electrical discharge machining will occur here.

Compared with the existing stepped groove processing methods, the advantages and beneficial effects of the present invention are as follows:

1) The present invention can complete the N (N≧2) order micro stepped groove processing of the array by the micro EDM technology, and can ensure the verticality of the stepped groove by compensating for electrode loss.

2) Compared with the traditional machining method of stepped groove machining, the machining accuracy of the method of the present invention is greatly improved, reaching the micrometer level, and compared with the traditional machining method, the array machining method will greatly improve the machining efficiency.

3) Compared with the existing MEMS stepped groove processing methods, such as LIGA multi-layer electroforming, multi-layer etching, etc., the accuracy and efficiency can be compared with this processing method, and its materials are greatly limited, only copper, nickel, etc. can be processed. Electroformable materials or etchable materials such as silicon and tungsten; and the size of the substrate material is strict, and it must be compatible with the MEMS process, which also greatly limits the selection of front and rear processes.

4) The processing method of the present invention can not only perform array batch processing with micron-level precision, but also perform multi-layer 2.5D micro-step groove processing for any material and workpiece size that can be processed by EDM. High compatibility and wide application prospects.

The stepped grooves of the micro-array processed by the method of the present invention can be used in the following fields (the following fields are only examples, and the present invention is not limited to the following fields):

1. Multilayer metal micro-molds are mainly used in micron-level multi-layer injection molds, such as microfluidic chips, biocompatible polymer microdevices, etc.

2. Various micron-level multi-layer 2.5D micro-mechanical parts, such as coaxial multi-stage micro-gears (double gears, reduction gears, etc.), micro-engines, micro-propellers used in aerospace and small aircraft, etc.

3. THz signal metal transmission line.

Description of drawings

FIG. 1 is a schematic diagram of the second-order micro-array stepped groove structure of micro-EDM.

Figure 2 is a schematic diagram of the arrangement of different patterns of second-order microarray electrodes with electrode loss compensation.

3 is a schematic diagram of an array pattern, wherein: a) the electrodes in the overlapping portion of the large pattern electrodes and the small patterns have patterns, and b) the electrodes in the overlapping portions of the large pattern electrodes and the small patterns do not have patterns.

FIG. 4 is a schematic diagram of a micro-positioning structure added when fabricating an electrode array pattern.

Figure 5 is a schematic diagram of the second-order micro-stepped groove processing, wherein:

(a) Using the electrode in Fig. 3-a), the small pattern structure is first processed, and the processing depth is deep, and then the large pattern structure is processed, and the processing depth is shallow;

(b) Using the electrode in Fig. 3-a), the large pattern structure is processed first, and the processing depth is shallow, and then the small pattern structure is processed, and the processing depth is deep;

(c) Using the electrode in Figure 3-b), the small pattern structure is first processed, and the processing depth is deep, and then the large pattern structure is processed, and the processing depth is shallow. There is no electrode structure in the overlapping part of the large pattern electrode and the small pattern electrode, that is, Electrical discharge machining does not occur here.

Detailed ways

The present invention will be described in further detail below through the embodiments and accompanying drawings. The embodiments described with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but not to be construed as a limitation of the present invention.

FIG. 1 is a schematic diagram of the structure of a second-order micro-array stepped groove by micro-EDM. The number of steps of the stepped groove is not limited, and the number is greater than or equal to two. The shapes of the stepped grooves in the figure include squares, circles, strips, triangles, and other shapes, including special-shaped shapes such as gears. The above four shapes are only examples and are not limited to the above figures.

FIG. 2 is a schematic diagram of the arrangement of different patterns of the second-order micro-array electrodes. The number of the patterns with different sizes corresponds to the number of steps of the stepped groove, and the number is not limited. In the micro-electrodes shown, the electrode loss compensation is performed by adding array electrodes of the same pattern to the same pattern, and the number of compensation array electrodes is not limited, and the number is greater than or equal to 2.

Figure 3 is a schematic diagram of the array pattern of different patterns, there are two types, among which a) there is a pattern in the overlapping part of the large pattern and the small pattern in the figure (that is, there is an electrode structure, and electrical discharge machining will occur here), b) the large pattern in the figure There is no pattern in the overlapping portion with the small pattern (ie, there is no electrode structure, and electrical discharge machining will not occur here).

Fig. 4 is a micro-positioning structure added when manufacturing an electrode array pattern, as shown in ① in the figure, such as a rectangle, a square, a point, a circle, and the like.

The processing methods of the micro-array electrodes include wire cutting, etching, LIGA process, electroforming and the like. Array electrode materials shown include copper and its alloys, nickel and its alloys, graphite and its compounds, tungsten and its alloys, and other spark electrode materials.

Figure 5 is a schematic diagram of the second-order micro-step groove processing. The electrode center is precisely aligned by one clamping (that is, only one clamping is required) and spindle translation, avoiding the alignment error caused by the traditional method of electrode replacement. First, a certain depth of processing is completed for one kind of micro-array pattern, and then another micro-array pattern is processed with different depths through positioning and alignment. The number of steps in the stepped groove is not limited, and the number is greater than or equal to 2. According to the different processing sequences of different graphics and the difference in the degree of overlapping of graphics, there are three processing methods:

a) Using the electrode in (a) of Fig. 3, first process the small pattern structure with a deep processing depth, and then process the large pattern structure with a shallow processing depth;

b) Using the electrode in (a) of Fig. 3, first process the large pattern structure with a shallow processing depth, and then process the small pattern structure with a deeper processing depth;

c) Using the electrode in (b) of Fig. 3, first process the small pattern structure, and the processing depth is deep; then process the large pattern structure, and the processing depth is shallow, and there is no electrode structure in the overlapping part of the large pattern and the small pattern, That is, electrical discharge machining does not occur here.

Although the exemplary embodiments and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made hereto without departing from the spirit of the invention and the scope of protection defined by the appended claims. For other examples, those of ordinary skill in the art will readily understand that the order of the process steps may be varied while remaining within the scope of the present invention. The protection scope of the present invention is based on the scope defined by the claims.

Claims (8)

1. A 2.5D EDM method of arrayed micro-stepped grooves, characterized in that, firstly, micro-array electrodes of different sizes and patterns are prepared, and then the micro-array electrodes of different sizes and patterns are respectively used to carry out electrical discharges of different depths on the workpiece. Spark machining to form stepped grooves in a micro-array with 2D pattern structures of different depths and different sizes stacked; the number of steps in the stepped groove is greater than or equal to 2, and the number of patterns with different sizes is the same as the number of steps in the stepped groove Correspondingly; a fine positioning structure is added during the preparation of the fine array electrode, which is used for positioning during the processing of the stepped groove. 2 . The method according to claim 1 , wherein the micro-array electrodes are prepared by one of the following methods: electric spark cutting process, LIGA process, electroforming process, and metal etching process. 3 . 3. The method of claim 1, wherein the material of the fine array electrodes is copper and its alloys, nickel and its alloys, graphite and its compounds, or tungsten and its alloys. 4. The method of claim 1, wherein the shape of the fine positioning structure is a straight line, a square, a point or a circle. 5 . The method of claim 1 , wherein, in the micro-array electrodes, the electrode loss compensation is performed by adding array electrodes with the same pattern in the same pattern, and the micro-positioning structure is also used to perform electrode loss compensation. 6 . when positioning. 6. The method according to claim 1, wherein the micro-array electrodes with patterns of different sizes are divided into two categories: a) an electrode structure exists in the overlapping portion of the large pattern and the small pattern, b) the large pattern and the small pattern have electrode structures. There is no electrode structure in the overlapping part of the pattern. 7. The method of claim 6, wherein the formation modes of the second-order stepped grooves are divided into the following three types: a) First, the small pattern structure is processed, and the processing depth is deep; then the large pattern structure is processed, and the processing depth is shallow, and the overlapping part of the large pattern and the small pattern has an electrode structure; b) First, the large graphic structure is processed, and the processing depth is shallow; then the small graphic structure is processed, and the processing depth is deep; c) First, the small pattern structure is processed, and the processing depth is deep; then the large pattern structure is processed, and the processing depth is shallow, and there is no electrode structure in the overlapping part of the large pattern and the small pattern. 8 . The method according to claim 1 , wherein when machining the stepped groove, the precise alignment of the electrode center is achieved by one clamping and spindle translation. 9 .

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