CN1943951A - Electrolytic processing method for ribbed deep small holes and special tool cathode - Google Patents

Abstract

The invention relates to a ribbed deep hole electrolytic machining method and a special tool cathode, belonging to the field of electrolytic machining. The method comprises the following steps: selecting a metal tube, using a negative copy electrode as a cathode, and processing a plurality of grooves on the outer surface of the metal tube; evenly coating pre-prepared epoxy resin glue in the groove; Install the positioning bracket at the end to make the forming tool electrode; process the light hole on the workpiece; extend the forming tool electrode into the deep light hole, and process the light hole into a ribbed hole. The invention has the advantages that the manufacturing method of the forming tool electrode is simple; the groove is coated with epoxy resin glue, which reduces the processing gap between the cathode and the anode, and improves the forming precision of the ribbed deep hole; the ring coated in the groove The epoxy resin glue is not easy to fall off, and the stability of the processing process is good, which significantly reduces the number of tool electrode repairs; the rotation of the spindle during the processing process ensures the uniformity of the size of the ribbed deep hole in the circumferential direction.

Description

Ribbed deep hole electrolytic machining method and special tool cathode

technical field

The ribbed deep hole electrolytic machining method and special tool cathode of the present invention belong to electrolytic machining

technology field.

Background technique

With the continuous development of engine technology, the requirements for engine thrust-to-weight ratio and booster ratio are getting higher and higher, and an important way to increase the thrust-to-weight ratio is to increase the temperature in the combustion chamber, which requires the engine to work at a higher temperature. As a result, higher requirements are put forward for the design and manufacture of the combustion chamber, especially for the cooling of the turbine blades. Modern engines are required to operate normally at a high temperature of more than 1300 degrees, which far exceeds the temperature that the engine blade materials can withstand. In order to ensure the normal operation of the engine, it is particularly important to take effective measures to solve the cooling problem of the engine blades. The ribbed cooling channel is a high-efficiency and low-resistance blade cooling form. It can be applied on the leading edge of the turbine blade, the blade pot, and the blade back. Usually, this ribbed channel is called "bamboo hole". During the heat transfer process of the bamboo hole, the ribs on the side wall of the cooling hole have a greater disturbance to the fluid. This disturbance destroys the boundary layer of the fluid in the cooling channel and reduces the thermal resistance generated by the thermal boundary layer. The conversion of cooling gas from laminar flow to turbulent flow is accelerated, and the heat exchange area is also increased, which has a better cooling effect. There is a patent document [Patent No.: US 6,303,193 B1] showing that the United States has used this cooling hole in the cooling of turbine blades and achieved good results. The processing method is as follows: first process a light hole, and then use the tool cathode prepared in advance to process the light hole into a slub hole by means of electrolytic processing. This processing method makes full use of the characteristics of electrolytic processing to remove materials in the form of ions, and its outstanding advantages such as no loss of tools during processing, high production efficiency, good surface quality of parts, and has nothing to do with material hardness. The manufacturing process of the tool cathode is as follows: Firstly, a layer of photoresist is coated on the surface of a cylinder; then, through a series of processes such as photolithography, exposure, and development, the surface of the cylinder is processed into a cross-distribution of photoresist and conductive layer. structure; finally, a positioning bracket is installed at the end of the electrode to make the cathode of a tool for processing ribbed deep and small holes. The tool cathode produced by this method, since the photoresist is directly coated on its outer surface, the processing gap between the conductive layer and the workpiece increases during processing, and the precision of the ribbed hole is low after processing; in addition, the photoresist is used for insulation , during electrolytic processing, the photoresist is easy to fall off; at the same time, it can be seen that the cathode preparation process of this tool is complicated, and each process step requires special equipment, which requires a large investment.

Contents of the invention

The purpose of the present invention is to provide a ribbed deep hole electrolytic processing method and a special tool cathode to solve the current difficulty in making electrodes for bamboo hole processing, the photoresist is easy to fall off, the processing process is unstable, and the processing efficiency and forming accuracy are low. question.

A ribbed deep hole electrolytic machining method is characterized in that it comprises the following steps:

(1) Process the light hole on the workpiece; (2) Prepare the cathode of the tool for processing ribbed deep small holes, and the cathode of the tool is a metal tube with an annular groove on the surface, and the groove is insulated with epoxy resin , the height of the insulating layer is lower than the height of the outer surface of the metal tube; (3), connect the workpiece to the positive pole of the electrolytic processing power supply, and clamp it on the workpiece mounting seat, and seal the lower end of the deep hole; (4), connect the cathode of the tool to the The electrolytic machining power supply is connected to the negative pole, and its upper end is connected to the feeding device through the tool cathode chuck; (5) Make the tool cathode extend into the light hole of the workpiece; (6) Supply electrolyte to the electrolysis area: the electrolyte passes through the tool cathode clamp The head flows in from the upper end of the internal channel of the cathode of the tool, flows out from the lower end of the cathode positioning bracket, flows to the bottom of the deep hole of the workpiece, then flows upward through the gap between the cathode positioning bracket and the workpiece, flows through the processing area, and finally flows out from the upper end of the deep hole of the workpiece; (7) Using the bamboo shape of the tool cathode, while the main shaft is rotating, multiple bamboo shapes with ribs are processed at one time in the light hole of the workpiece.

A special tool electrode for ribbed deep and small hole electrolytic machining, characterized in that: the main body of the electrode is a metal tube with an annular groove on the surface, and epoxy resin glue is coated in the groove, and the height of the epoxy resin glue is lower than that of the metal pipe. The height of the outer surface of the tube.

The advantage of the above processing method is that in the electrolytic processing of the bamboo hole, the manufacturing method of the forming tool electrode is simple, the side wall of the metal tube electrode is processed into a groove shape, and the epoxy resin glue is evenly coated in the metal tube groove to make the tool cathode. The thickness of the epoxy resin should not be higher than the outer diameter of the metal tube electrode. Compared with the photoresist coating on the surface of the cylinder, the processing gap between the cathode and the anode is smaller during processing, and the ribs with a more obvious shape can be processed. High precision. In addition, the epoxy resin glue has good corrosion resistance, is not easy to fall off during processing, and the processing stability is significantly improved. The use of forming tool electrodes improves the efficiency of electrolytic machining of bamboo holes.

In addition, the rotation of the main shaft during processing improves the flow field between the cathode and the anode, improves the processing stability, and improves the dimensional consistency of the ribbed deep and small holes in the circumferential direction. By adopting the above process method, the ribbed deep small holes can be processed quickly and conveniently at a lower cost.

Description of drawings

Figure 1 is a schematic diagram of the fabrication process of the forming tool cathode. Wherein Fig. 1 (a) is the straight pipe before processing; Fig. 1 (b) is the groove of side wall of tube electrode processed by negative copy method; 1 (c) is the smooth straight pipe with side wall processed into groove; Fig. 1 ( d) Apply epoxy resin glue to the groove, and install the cathode positioning bracket to make the tool electrode.

Fig. 2 is a schematic diagram of electrolytic machining bamboo holes. Among them, Figure 2(e) is a schematic diagram before processing; Figure 2(f) is a schematic diagram after processing.

Fig. 3 is a diagram of an electrolytic machining device for a bamboo-jointed hole in a workpiece.

Label name in Fig. 1: 13, smooth straight tube, 14, central hole, 18, anti-handcuffed cathode, 16, the groove processed on the outer wall of the tool electrode, 17, the part of the tool electrode that is not insulated, 18, the reverse copy electrode .

Names of labels in Figure 2: 1. light hole, 2. workpiece, 3. electrolyte inlet, 4. epoxy resin, 5. metal tube, 6. gap between cathode and anode, 7. cathode positioning bracket, 8. workpiece Mounting seat, 9, sealing gasket, 10, gap between cathode positioning bracket and workpiece, 11, slub hole, 12, processed rib.

Label name in Fig. 3: 19, computer, 20, pressure gauge, 21, flow meter, 22, regulating valve, 23, filter, 24, gear pump, 25, heater, 26, temperature sensor, 27, liquid storage tank , 28, temperature controller, 29, bamboo hole processing tool cathode, 30, processing cavity, 31, pressure plate, 32, processing power supply, 33, tool electrode chuck, 34, transmission mechanism, 35, motor.

Detailed ways

The following describes in detail how to process the ribbed cooling holes in the engine blade and the preparation of the tool cathode with reference to FIGS. 1 to 3 .

Step 1: Firstly, the light hole 1 is machined on the workpiece by electrolytic machining.

The second step: prepare the cathode 28 of the tool for processing bamboo joint holes as shown in FIG. 1 . Choose a metal tube 13 with good electrical conductivity as the basic material of the tool electrode, as shown in Figure 1(a), its cross-sectional shape is circular, and the metal material is corrosion-resistant. Adopt a reverse copy cathode 18, utilize the electrolytic machining reverse copy method to process the outer wall surface of the metal tube into a groove-shaped 16 structure as shown in Figure 2 (c), the depth of the groove 16 should be smaller than the difference between the outer diameter of the metal tube and the inner warp size, The width of the groove 16 can be processed according to the needs. Apply the epoxy resin insulating glue 4 in the processed groove 16. After it dries, install the cathode positioning bracket 7 on the electrode end of the metal tube. The outer wall of the cathode positioning bracket should be processed with a slope 8. Ensure the smoothness of the electrolyte flow channel. It should be pointed out that the size of the metal tube electrode 13 should be determined according to the size of the aperture 1 of the bamboo joint to be processed, and the diameter cannot be too small or too large.

The third step: the transmission mechanism 34 controlled by the computer 19 as shown in Fig. 3, the tool electrode 29 connected with the workpiece 2 by a carbon brush, the electrolytic processing power supply 32, the electrolyte temperature controller 28, and the temperature controller is connected to the liquid storage tank 27 Inside heater 25 and temperature sensor 26, the gear pump 24 that links to each other with liquid reservoir 27 and filter 23, regulating valve 22, flowmeter 21, the electrolytic solution circulation system that pressure gauge 20 forms are connected in processing cavity 30, also Including placed in the processing chamber, the workpiece is pressed on the workpiece mounting seat 8 by the pressing plate 31, and the forming tool electrode 29 placed on the electrode chuck 33 is connected to the transmission device. The forming tool electrode 29 constituting the electrolytic machining device for bamboo joints is installed on the machine tool spindle through the tool electrode chuck 33 . The electrolyte passes through the tool cathode chuck 33, flows in from the upper end 3 of the inner channel of the tool cathode, flows out from the lower end 10 of the cathode positioning bracket, flows to the bottom of the deep hole of the workpiece, and then flows upward through the gap 6 between the tool cathode and the workpiece, and flows through the processing area , and finally flow out from the upper end of the workpiece deep hole. As the reaction progresses, the inner surface of the anode of the workpiece changes, the metal material near the conductive layer 17 dissolves to form bamboo holes 11 , and the material near the insulating layer 4 is not etched to form ribs 12 . Using the bamboo shape of the tool cathode 29, a plurality of bamboo shapes 11 with ribs 12 are processed at one time in the light hole of the workpiece.

In the first step to process the light hole 1, in addition to the formed tube electrolytic machining method, the method of electric spark perforation can also be used. When the depth of the hole is small, drilling can also be used for processing.

When preparing the tool cathode 29, the groove 16 around the tube electrode can also be processed by other machining methods besides the electrolytic machining method. Considering the deformation of the tool cathode after machining, it is best to use the electrolytic machining method without cutting force for machining. Moreover, the anti-handcuffed cathode 15 is adopted, and the electrolytic machining method has higher machining efficiency than other methods.

The principle and process of "ribbed deep small hole electrolytic machining method and special tool cathode" of the present invention are further summarized as follows:

A light hole 1 is processed on the processing part in advance, and the processing of the light hole can be processed by electrolysis, electric spark or drilling. Adopt the method of wire electric discharge cutting to process a reverse copy cathode 18; With reference to Fig. Several grooves 16 are machined into the wall. The groove 16 cannot be too deep to ensure the strength of the tool electrode, and the size of the groove 16 determines the width of the rib 12 and the width of the slub hole 11 for final processing. The epoxy resin glue 4 is evenly coated in the groove 16, and the thickness of the epoxy resin glue 4 should not be higher than the outer diameter of the metal tube electrode 13. Compared with applying photoresist on the surface of a cylinder, the gap between the cathode and anode during processing The processing gap 6 is smaller, the rib 12 with a more obvious shape can be processed, and the processing accuracy is high. The cathode positioning bracket 7 is very important to the processing stability. The material of the cathode positioning bracket 7 is a non-conductive material, which has a certain strength, which can ensure the stable positioning of the tool electrode 28, and avoid the occurrence of short circuits during processing and shocks during processing. The tool electrode 28 caused by the liquid swings, and the slope 8 on the side of the cathode positioning bracket 7 ensures the smooth flow of the electrolyte. The workpiece 2 is installed on the workpiece mounting seat 8 and pressed tightly by the pressure plate 31 to ensure that the bottom of the workpiece is well sealed. Before processing, the relative position of the forming tool electrode 28 and the workpiece 2 is adjusted. The regulating valve 22 finally flows into the processing area through the central hole 3 of the tube electrode, so that the pressure in the processing area remains stable, and the processed products are fully taken out of the processing area. The temperature controller 28 controls the heating device to keep the electrolyte temperature constant. Before the power supply 32 is turned on, the forming tool electrode 29 is fed to a certain depth under the drive of the machine tool spindle 19, and the tool electrode 29 is turned on when the power supply 32 is turned on. on the uniformity. By setting different processing parameters, the shapes of the bamboo joint holes 11 with different size requirements can be processed. The bamboo-shaped hole electrolytic machining method of the workpiece can stably process the bamboo-shaped cooling hole, and solves the problems that the bamboo-shaped hole is difficult to process and the processing efficiency is low.

Claims (3)

1. A ribbed deep hole electrolytic machining method is characterized in that it comprises the following steps: (1), processing the light hole (1) on the workpiece (2); (2), prepare the ribbed deep hole (11) processing tool cathode (29), and the tool cathode is a metal tube (13) with an annular groove (31) on the surface, and the groove is insulated by epoxy resin treatment, the height of the insulating layer is lower than the height of the outer surface of the metal pipe; (3) Connect the workpiece (2) to the positive electrode of the electrolytic processing power supply, and clamp it on the workpiece mounting base (8), and seal the lower end of the deep hole (9); (4), the tool cathode (29) is connected to the negative electrode of the electrolytic machining power supply, and its upper end is connected to the feed device (34) through the tool cathode chuck (33); (5), making the tool cathode (29) extend into the light hole (1) of the workpiece; (6) Electrolyte is supplied to the electrolysis zone: the electrolyte flows in from the upper end (3) of the internal channel of the tool cathode (29) through the tool cathode chuck (33), flows out from the lower end (10) of the cathode positioning bracket (7), and flows to the bottom of the deep hole of the workpiece, and then flow upward through the gap (6) between the cathode positioning bracket (7) and the workpiece (2), flow through the processing area, and finally flow out from the upper end of the deep hole of the workpiece; (7), utilize the slub profile of tool cathode (29), when main shaft rotates, a plurality of slub (11) shapes with ribs (12) are processed once in the workpiece light hole. 2. The electrolytic machining method for ribbed deep and small holes according to claim 1, characterized in that the preparation of the cathode of the tool adopts the following steps: (1), process the sheet-shaped counter-copy electrode (18) with rectangular tooth shape; (2), select the metal tube (13), use the counter copy electrode as the cathode, and process some annular grooves (31) on the side wall of the metal tube; (3), coat the epoxy resin glue (4) whose height is lower than the height of the outer surface of the metal pipe in the groove (31); (4), the lower end of the tool cathode (29) is equipped with an insulating cathode positioning bracket (7); 3. A special tool electrode for electrolytic machining of ribbed deep small holes, characterized in that: the main body of the electrode is a metal pipe (13) with an annular groove (31) on the surface, and the groove is coated with epoxy resin glue (4 ), the height of the epoxy glue is lower than the height of the outer surface of the metal pipe.

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