CN103008802A - High-instantaneous-energy-density electric spark high-speed milling method - Google Patents

Abstract

The invention relates to a high-instantaneous-energy-density electric spark high-speed milling method, which belongs to the field of machining. The method comprises the following steps of: connecting a rotary rod-like electrode with an inner flushing fluid hole with a negative electrode of a power supply, connecting a to-be-machined workpiece with a positive electrode of the power supply and melting to remove the workpiece material by utilizing high-instantaneous-energy-density spark discharge between the electrodes and the workpiece in a machining process; discharging molten material out of a discharge gap by working fluid which flows at a high speed; and cooling the machined workpiece. According to the method, by utilizing high-instantaneous-energy-density spark discharge and a high-pressure forced inner flushing fluid and low-pressure outer flushing fluid combined method, the stability and the high efficiency of machining are realized, and high-efficiency machining on any conductive material, including conventional difficult-to-machine materials such as engineering ceramic with weak conductivity and high-temperature alloy, can be realized.

Description

High Instantaneous Energy Density EDM High Speed Milling Method

technical field

The invention relates to a high-instantaneous-energy-density electrical discharge high-speed milling method, which belongs to the field of mechanical processing.

Background technique

At present, traditional processing methods are difficult to efficiently process some materials with high hardness, high strength, high toughness and high brittleness, and the processing cost is generally high. The processing of some nickel-based alloys, titanium-based alloys and some engineering ceramics commonly used in the aerospace field has always been a difficult problem in the processing field. Electric discharge machining provides an effective method for the processing of the above materials. Compared with expensive high-speed milling equipment and its processing cost, the electric discharge machining method reflects its good economy. EDM is a machining method that removes material by continuous spark discharge between the electrode and the workpiece to be machined. Since there is no direct contact between the tool electrode and the workpiece, EDM has the advantages of small macro force, low rigidity requirements for machine tools, and easy precision machining. However, the current electrical processing equipment generally has the disadvantage of low material removal efficiency.

Chinese Patent Document No. CN 1657208A describes a cluster electrode used for electric discharge machining that can realize large-flow internal flushing. The beneficial effect of cluster electrodes is that the discretization of integral shaped electrodes can be aggregated from a large number of tubular or rod-shaped unit electrodes, so that the processing of shaped electrodes with complex contours and high processing costs is simplified. The combination of simple tubular or rod-shaped unit electrodes produced at low cost can greatly reduce the electrode cost and shorten the production time.

Chinese Patent Document No. CN 102091839 A further discloses a cluster electrode high-speed discharge machining method. The above-mentioned processing method uses cluster electrodes to realize high-pressure, high-flow porous internal flushing, and uses a hydrodynamic arc-breaking mechanism to ensure short-arc discharge machining. The processing method is a forming processing method, that is, the tool electrode and the workpiece do not rotate relative to each other, which reduces the processing flexibility.

The inventor found through experiments that: adopting the milling processing method, and applying sufficient flushing energy and sufficient discharge energy to the discharge gap, it can be used on a machine tool with three-axis or more automatic servo feed and retraction functions. Realize high-speed EDM.

Contents of the invention

The present invention aims at the above-mentioned deficiencies in the prior art, and provides a "high-instantaneous-energy-density EDM high-speed milling method", which uses the high-instantaneous energy-density spark discharge between the electrode and the workpiece to melt the workpiece material; high-speed flow work The liquid discharges the molten material out of the discharge gap to ensure the stability of processing; with the help of machine tools with three-axis or more automatic servo feed and retract functions, high-speed EDM processing can be realized simply, conveniently and economically. The method is especially suitable for high-speed machining of complex curved surfaces and super-large cavities.

The present invention is achieved through the following technical solutions. In the present invention, the rod-shaped graphite electrode containing single or multiple inner flushing holes is clamped on the main shaft of the machine tool with the function of inner flushing, so that it rotates with the main shaft of the machine tool at a certain speed; a set of outer flushing mechanism is provided outside the electrode , so that the working fluid with different pressure and flow rate provided by the water-based working fluid supply system can be delivered to the discharge gap composed of the electrode and the workpiece through the machine tool spindle and the external flushing mechanism at the same time. During the processing, the electrode and the workpiece are respectively connected to the DC The negative pole and positive pole of the power supply or the DC pulse power supply realize the removal of the workpiece material through the continuous high instantaneous energy density spark discharge between the electrode and the workpiece.

The working fluid supply system can provide water-based working fluid with a certain pressure and flow rate to the flushing hole of the rotating electrode through the machine tool spindle with internal flushing function, and make it flow through the discharge gap composed of the electrode and the workpiece.

The working fluid supply system can also provide a layer of water-based working fluid with a certain thickness and high-speed flow along the outer surface of the rotating electrode to the discharge gap through the external flushing mechanism.

The tool electrode refers to a high-purity rod-shaped graphite electrode containing single or multiple flushing holes.

The rotational speed of the tool electrode is 0-10000 r/min.

The discharge power supply refers to a high-power DC pulse power supply with a pulse width and a pulse interval ranging from 0.1 to 1000 ms, a peak voltage of 50 to 300 V, and a peak current of 100 to 5000 A.

The machine tool mentioned above refers to a machine tool with at least three-axis automatic servo feed and retract functions.

The water-based working fluid is an oil-in-water emulsion with a water content greater than 95%.

The beneficial effect of the present invention lies in: using spark discharge with high instantaneous energy density for material erosion, and adopting the method of combining internal flushing liquid and external flushing liquid to ensure processing stability, which is much higher than that of ordinary EDM. The obtained material removal ability; the machining process can adopt the three-axis or multi-axis linkage method, which can easily realize the efficient machining of complex curved surfaces and large cavities. The processing method can realize high-efficiency processing of other traditional difficult-to-process conductive materials such as engineering ceramics and high-temperature alloys with certain conductivity.

Description of drawings

Figure 1 is a schematic diagram of high instantaneous energy density EDM high-speed milling equipment.

Figure 2 is a schematic diagram of the principle of EDM high-speed milling with high instantaneous energy density.

Detailed ways

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

As shown in Figure 1, the application environment of this embodiment includes: a rod-shaped graphite electrode 1 with a single inner flushing hole, a workpiece to be processed 2, a discharge power supply 3, a water-based working fluid supply system 4, an outer flushing mechanism 5, and a The machine tool spindle 6 with flushing function, wherein: the tool electrode 1 is clamped on the machine tool spindle 6 with the internal flushing function, and rotates with the spindle at a certain speed, and an external flushing mechanism 5 is provided outside the tool electrode 1 to make The working fluid with different pressures and flow rates provided by the water-based working fluid supply system 4 is delivered to the discharge chamber composed of the tool electrode 1 and the workpiece 2 through the machine tool spindle 6 with the internal flushing function and the external flushing mechanism 5 at the same time. The gap is to rapidly cool the molten material and quickly discharge it out of the discharge gap, as shown in Figure 2. During the processing, the workpiece and the electrode are respectively connected to the positive and negative poles of the DC pulse power supply, and the high-efficiency processing of the workpiece is realized through the continuous high instantaneous energy density spark discharge between the electrode and the workpiece.

Example 1

Using a machine tool with three-axis automatic servo feed and retract function, the spindle speed is 3000 r/min, the diameter of the tool electrode 1 is 10 mm, the diameter of the central flushing hole is 4 mm, and the material is high-purity graphite. The material of workpiece 2 is die steel 8407, and the pulse width is 3 ms, the pulse interval is 1 ms, the peak voltage is 80 V, and the peak current is 800 A. The working fluid is an oil-in-water emulsion with a water content of 95%. , the working fluid pressure provided by the internal flushing system is 0.5 MPa, and the outlet pressure of the working fluid provided by the external flushing system is 0.3 MPa. The machining trajectory is that the tool electrode is fed vertically downward by 5 mm, and then moves horizontally by 50 mm. A keyway structure was processed, and the material removal rate of the obtained die steel 8407 was 8952 mm ³ /min.

Example 2

Change the workpiece material to fully verify the universal applicability of high-speed arc discharge milling to different materials. The workpiece material is selected as titanium alloy (model TC4), and other processing conditions in Example 1 are kept unchanged. The material removal rate of TC4 is 14263 mm ³ /min.

Example 3

Select the workpiece material as carbon steel (S45C), keep other processing conditions unchanged in Example 1, and the material removal rate of carbon steel S45C is 10127 mm ³ /min.

Claims (7)

1. A high-instantaneous-energy-density EDM high-speed milling method, characterized in that, the rod-shaped electrode containing a single or multiple inner flushing holes is clamped on the machine tool spindle with the inner flushing function, so that it can rotate at a certain speed The main shaft of the machine tool rotates; a set of external flushing mechanism is set outside the electrode, so that the working fluid with different pressure and flow rate provided by the water-based working fluid supply system can be delivered to the electrode and the workpiece through the machine tool spindle and the external flushing mechanism at the same time. During the machining process, the workpiece and the electrode are respectively connected to the positive and negative poles of the DC pulse power supply, and the high instantaneous energy density spark discharge between the electrode and the workpiece realizes efficient machining of the workpiece. 2. The high-instantaneous-energy-density EDM high-speed milling method according to claim 1, characterized in that, the working fluid supply system can provide the flushing hole of the rotating electrode through the machine tool spindle with internal flushing function. The water-based working fluid with a certain pressure and flow makes it flow through the discharge gap composed of electrodes and workpieces. 3. The high instantaneous energy density EDM high-speed milling method according to claim 1, wherein the working fluid supply system can also provide a layer with a certain thickness along the outer surface of the rotating electrode through the external flushing mechanism. The working fluid flowing to the discharge gap at high speed. 4. The high-instantaneous-energy-density EDM high-speed milling method according to claim 1, wherein said tool electrode is a high-purity rod-shaped graphite electrode containing single or multiple flushing holes. 5. The high-instantaneous-energy-density EDM high-speed milling method according to claim 1, wherein the discharge power source refers to: the pulse width and pulse interval are respectively 0.1-1000 ms, and the peak voltage is 50-1000 ms. 300 V, high-power DC pulse power supply with a peak current of 100~5000 A. 6. The high-instantaneous-energy-density EDM high-speed milling method according to claim 1, wherein said machine tool refers to a machine tool with at least three-axis automatic servo feed and retraction functions. 7. The high-instantaneous-energy-density EDM high-speed milling method according to claim 1, wherein the water-based working fluid is an oil-in-water emulsion with a water content greater than 95%.

Images