CN111673210A - High-speed arc machining device and machining method using suck-back electrode - Google Patents

Abstract

The invention discloses a high-speed electric arc machining device and a machining method adopting a resorption type electrode. The medium liquid circulates among the suction pump, the liquid storage tank, the flushing pump, the rotating spindle and the tool electrode in sequence. The liquid outlet channel and the liquid return channel are integrally arranged on the tool electrode to complete the supply and recovery of the medium liquid during processing, the negative pressure effect of the suction pump can be fully utilized, and a negative pressure environment is formed in a narrow processing gap filled with the medium liquid. The negative pressure environment enables the fluid arc breaking effect of the processing area to be more stable, pressure loss of medium liquid flowing from the liquid outlet channel to the open environment is avoided, the arc breaking effect is more obvious, and the surface quality of the processing area can be effectively improved.

Description

High-speed arc machining device and machining method using suck-back electrode

technical field

The invention relates to the field of electric discharge machining, in particular to a high-speed electric arc machining device and a machining method using a suck-back electrode.

Background technique

Arc discharge machining is a general term for a machining method in which an effective and controllable arc discharge is formed between the tool electrode and the workpiece, and the heat of the formed plasma is used to erode the workpiece material. Arc discharge machining is a near-steady-state self-sustained discharge plasma generated under the condition of high current and long pulse. The arc column has a high energy density, and the corresponding electron and ion temperature are also high. However, if the discharge arc column resides on the surface of the workpiece, it will burn the workpiece and the electrode. Therefore, the use of mechanical motion and fluid power to achieve arc breaking or a combination of both can effectively make the arc column move quickly on the workpiece surface or even cut off. , to avoid the formation of an arc dwelling at a certain point. Similarly, the workpiece material is rapidly melted or even vaporized under the action of high-energy-density arc plasma, and the re-solidified eroded particles are easy to accumulate on the surface of the workpiece, reducing the discharge gap between the tool electrode and the workpiece material and causing secondary discharge even short circuit. Therefore, effective chip removal with high-speed fluid is also beneficial to avoid surface burns and ensure the continuity of processing.

Therefore, high-speed arc discharge milling and submerged machining are realized based on mechanical motion, hydrodynamic arc breaking mechanism, and combined with the negative pressure environment in the processing area. The device enhances the arc breaking efficiency and cooling effect of the high-speed arc discharge process through the negative pressure environment, reduces the surface roughness, reduces the thickness of the heat-affected zone, and improves the quality of the machined surface under different processing conditions.

For example, the patent document "A Non-destructive Electrode for EDM" with application number CN201410137565.4 discloses an electric spark discharge process between the conductive liquid and the workpiece that wraps the tool electrode. The outer conductive liquid of the absorber is continuously supplied with electro-liquid to achieve the effect of non-destructive discharge of the electrode. Although the non-destructive electrode device can use the conductive liquid to replace the tool electrode for discharge without compensation for electrode loss, the discharge gap between the conductive liquid and the workpiece material is theoretically guaranteed to remain relatively unchanged, but the particles of the eroded material are fine, which may cause the conductive liquid The clogging of the absorber affects the relatively stable discharge state between the conductive liquid and the workpiece material.

For example, as disclosed in the patent document "Arc Welding Method of Melting Electrode Annular Negative Pressure" with application number CN201610018258.3, it is disclosed that the degree of restraint of the restrained arc is controlled by adjusting the negative pressure area inside the hollow tubular electrode, thereby changing the energy density of the arc and the voltage of the arc. and arc characteristics such as arc pressure. The device can realize the control of welding heat input and welding seam forming, but due to the complex device and fixed position, it cannot realize the complex multi-axis servo motion in high-speed arc discharge machining. And it is used in the field of arc welding, emphasizing the stability of the arc. In high-speed arc discharge machining, the negative pressure environment is used to assist in arc breaking.

Another example is a type of arc three-dimensional machining method, in which arc machining is performed on a designated area in a closed chamber. The liquid medium with a pressure of 0.4-0.7Mpa flows in from the side opening of the chamber and flows out from the internal flow channel of the electrode, and performs external flushing cooling and arc breaking for the arc machining discharge area, and the rest are kept sealed. This type of method uses a DC power supply, and the duration of the discharge plasma is directly related to the liquid flow rate. The effect of pulse discharge with different pulse widths is achieved by adjusting the flow rate of the liquid medium. During the machining process, the sealed chamber is fixed around the machining area and remains stationary, only the submerged machining of the machining area is realized, and the machining method is single. In this method, the electrode only feeds in the machining direction, and there is no rotational movement. It only relies on the hydrodynamic arc breaking mechanism, which cannot guarantee the effective cutting of the arc. The machining process is unstable, and it is easy to burn the machined surface, resulting in a deep heat-affected zone of the material. And the surface hardness difference is large and other problems that affect the subsequent finishing. Among the processing parameters, the current is 100-500A, and the voltage is 25-35V, which belongs to arc processing with small discharge energy, and the material removal rate is limited.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a high-speed arc machining device and a machining method using a suck-back electrode, which can solve the above-mentioned related problems.

Purpose of the present invention adopts following technical scheme to realize:

A high-speed arc machining device using a suction-back electrode, the device includes a rotating spindle, a tool electrode, a spindle casing, a suction pump, a liquid storage tank and a flushing pump, the tool electrode is fixed on the rotating spindle, and the rotating spindle is insulated and connected On the spindle of the machine tool, and rotate with the spindle of the machine tool at a high speed to realize the mechanical motion arc breaking during the machining process; the medium liquid circulates in sequence among the suction pump, the liquid storage tank, the flushing pump, the rotating spindle and the tool electrode. The tool electrode adopts a porous back-suction structure, and the tool electrode includes an electrode body, a joint, an electrode liquid outlet channel and a plurality of electrode liquid return channels; the joint is arranged on the upper outer wall of the electrode body and is used for Connection with the rotating main shaft; a through hole is opened in the axis of the electrode body to form the electrode liquid outlet channel, the upper end of the electrode liquid outlet channel is communicated with the medium flow channel of the rotating main shaft, and the electrode liquid outlet channel It is used as an inner flushing flow channel to spray medium liquid to the processing area on the surface of the workpiece; a plurality of the electrode liquid return channels are evenly distributed around the electrode liquid outlet channel in the axial direction of the electrode body. The upper part of the body corresponds to the upper ends of the plurality of electrode liquid return passages, and an annular liquid return ring is provided, and the circumferential direction of the liquid return ring is provided with a liquid return hole, through which the liquid return hole and the suction pump are connected. In fluid communication, the electrode liquid return channel is used as an external pumping liquid channel to pump back the medium liquid in the processing area.

Preferably, the diameter of the electrode liquid return channel is smaller than the radius of the electrode liquid outlet channel.

Preferably, the flushing pump includes a pump body and a control valve; the suction pump includes a pump body, a control valve and a filter.

A processing method using the above device is as follows.

In preparation for arc machining, firstly, the workpiece material is insulated and fixed on the worktable of the machine tool, the tool electrode is fixed on the rotating spindle, and the rotating spindle is fixedly connected with the machine tool spindle and kept insulated; the workpiece material and the tool electrode are respectively connected to the two poles of the discharge power supply Then the electrode liquid return channel is communicated with the suction pump through the liquid return channel opened on the rotating spindle and the liquid return hole opened on the main shaft shell; the discharge gap between the workpiece material and the tool electrode is set by the machine tool servo system .

In high-speed arc machining, the medium liquid in the liquid storage tank reaches a high pressure state through the flushing pump and flows through the rotating spindle and the electrode liquid outlet of the tool electrode to provide high-pressure internal flushing to the processing area; the high-pressure internal flushing realizes hydrodynamic arc breaking and The eroded particles are quickly washed away from the processing area; in the negative pressure environment of the machining gap, the medium liquid entrained with the eroded particles flows through the electrode return channel, the liquid return loop on the rotating spindle and the return liquid on the spindle shell The holes are filtered by the suction pump and drawn back to the machine tool liquid storage tank to form a liquid supply circulation system.

After the machining is completed and the discharge is stopped, the spindle of the machine tool stops rotating, the tool electrode stays at the end of the machining position for a short time, and the liquid medium with metal erosion particles is fully pumped out by the suction pump; downtime.

Preferably, the discharge power supply adopts periodic pulse power supply, the voltage value is 30-120V, the peak current is 50-10000A, and the provided pulse width and pulse interval range are 2μs-20000μs.

Compared with the prior art, the beneficial effects of the present invention are: 1. The tool electrode adopts a porous back-suction structure, the electrode liquid outlet channel and the electrode liquid return channel are closely arranged, and a negative pressure environment is generated in the arc machining gap, which can timely and effectively The arc plasma in the discharge gap performs negative pressure arc breaking. 2. Because the negative pressure area is full of medium flow and the space is narrow, the pressure loss of negative pressure is small, which avoids the instability and discontinuity of the arc breaking mechanism of negative pressure, and effectively improves the quality of the machined surface. 3. The eroded particles of the workpiece material are taken away by the medium liquid faster in the negative pressure environment, avoiding abnormal discharge states such as short circuit and secondary discharge. 4. The negative pressure arc breaking function relies on the liquid supply and circulation system composed of the suction pump, the liquid storage tank, the flushing pump, the rotating spindle and the tool electrode. There is no additional complicated auxiliary equipment at the tool electrode end, which can adapt to the sinking. Various machining methods such as in-line machining, hole machining and surface machining on impeller blades.

Description of drawings

Fig. 1 is a kind of schematic diagram of the high-speed arc machining device adopting the suck-back electrode of the present invention;

Fig. 2 is the enlarged schematic diagram of B place in Fig. 1;

FIG. 3 is a schematic diagram of a tool electrode used in the embodiment shown in FIG. 1 .

In the figure: 1. Rotating spindle; 11. Liquid return ring; 2. Tool electrode; 21. Electrode body; 22. Joint; 23. Electrode liquid outlet; 24. Electrode liquid return; 5. Spindle shell; 8. Flushing pump; 9. Suction pump; 10. Liquid storage tank.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

Referring to Figures 1 to 3, an internal flushing negative pressure suction device for high-speed arc discharge machining, the device includes a rotating spindle 1, a tool electrode 2, a spindle housing 5, a suction pump 9, a liquid storage tank 10 and a punch Liquid pump 8, the tool electrode 2 is fixed on the rotating spindle 1, and the rotating spindle 1 is insulated and connected to the machine tool spindle, and rotates with the machine tool spindle at high speed to realize the mechanical motion arc breaking during the machining process; the medium liquid is in the suction pump. 9. The liquid storage tank 10, the flushing pump 8, the rotating spindle 1 and the tool electrode 2 circulate in sequence.

The tool electrode 2 adopts a porous suction-back structure, and the tool electrode 2 includes an electrode body 21 , a joint 22 , an electrode liquid outlet channel 23 and a plurality of electrode liquid return channels 24 (see FIG. 3 ). The joint 22 is arranged on the upper outer wall of the electrode body 21 for connection with the rotating spindle 1; a through hole is opened in the axis of the electrode body 21 to form the electrode liquid outlet channel 23, and the electrode liquid outlet channel The upper end of 23 is communicated with the medium flow channel of the rotating spindle 1, and the electrode liquid outlet channel 23 is used as an inner flushing flow channel to spray medium liquid to the processing area of the workpiece surface; The electrode liquid outlet channel 23 is provided with a plurality of the electrode liquid return channels 24 evenly distributed in a ring shape, and an annular liquid return ring channel 11 is opened on the rotating spindle 1, and is connected with the plurality of electrode liquid return channels 24. The upper end corresponds to; a circumferential liquid return hole is set on the main shaft housing 5, which corresponds to the liquid return ring 11 (see FIG. 1); the liquid return hole is in fluid communication with the suction pump 9, so The electrode liquid return channel 24 is used as an external pumping liquid channel to pump back the medium liquid in the processing area.

Among them, the joint 22 is preferably a threaded joint.

Alternatively, a plurality of electrode liquid outlet channels 23 may be provided. Preferably, it is arranged in the center of a plurality of electrode liquid return channels 24 arranged in an annular array.

Further, the diameter of the electrode liquid return channel 24 is smaller than the radius of the electrode liquid outlet channel 23 .

Alternatively, the function of the liquid return ring 11 and the liquid return hole is to provide a channel for the medium flow to return to the liquid storage tank 10 under a negative pressure environment. It is preferably arranged on the rotating spindle 1 and the spindle housing 5, respectively.

Processing step or process: The tool electrode 2 has an electrode liquid outlet channel 23 (inner flushing liquid channel) and a plurality of electrode liquid return channels 24 (external pumping liquid channel). The tool electrode 2 is fixed on the rotating main shaft 1 and rotates with the rotating main shaft 1 at a high speed, so as to achieve the effect of mechanical motion arc breaking during the machining process. The workpiece is fixed on the machine table. The distance between the tool electrode 2 and the workpiece surface is adjusted to a suitable discharge gap through the servo motion of the machine tool. During high-speed arc machining, the medium liquid in the liquid storage tank 10 reaches a high pressure state through the flushing pump 8 and flows through the inner flow channel of the rotating spindle 1 and the inner flushing flow channel of the tool electrode 2 to provide the inner flushing liquid to the machining area, so as to realize Hydrodynamic arc breaking. Due to the action of flushing in the high-pressure fluid medium, the discharge gap and its surrounding area are filled with the liquid medium. At the same time, under the action of the suction pump 9 , the external pumping liquid channel of the tool electrode 2 forms a negative pressure, and the liquid medium in the discharge gap is pumped away. The final medium liquid is returned to the liquid storage tank 10 .

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it can still be The technical solutions described in the foregoing embodiments are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (5)

1. The high-speed electric arc machining device adopting the resorption type electrode comprises a rotating main shaft (1), a tool electrode (2), a main shaft shell (5), a suction pump (9), a liquid storage tank (10) and a flushing pump (8), wherein the tool electrode (2) is fixed on the rotating main shaft (1), the rotating main shaft (1) is connected to a machine tool main shaft in an insulating way and rotates at a high speed along with the machine tool main shaft to realize mechanical motion arc breaking in the machining process; medium liquid circulates in proper order between suction pump (9), liquid reserve tank (10), towards liquid pump (8), rotatory main shaft (1) and tool electrode (2), its characterized in that:

the tool electrode (2) adopts a porous resorption type structure, and the tool electrode (2) comprises an electrode body (21), a joint (22), an electrode liquid outlet channel (23) and a plurality of electrode liquid return channels (24); the joint (22) is arranged on the outer wall of the upper part of the electrode body (21) and is used for being connected with the rotating main shaft (1); a through hole is formed in the axis of the electrode body (21) to form the electrode liquid outlet channel (23), the upper end of the electrode liquid outlet channel (23) is communicated with the medium flow channel of the rotating main shaft (1), and the electrode liquid outlet channel (23) is used as an inner flushing liquid flow channel to spray medium liquid to a processing area on the surface of a workpiece; the electrode liquid return passage is characterized in that a plurality of electrode liquid return passages (24) are annularly and uniformly distributed around the electrode liquid outlet passage (23) in the axial direction of the electrode body (21), an annular liquid return ring passage (11) is formed in the position, corresponding to the upper ends of the plurality of electrode liquid return passages (24), of the upper portion of the electrode body (21), liquid return holes are formed in the circumferential direction of the liquid return ring passage (11) and are communicated with the suction pump (9) through the liquid return holes, and the electrode liquid return passages (24) are used as outer liquid suction passages to draw back medium liquid in a machining area.

2. The apparatus of claim 1, wherein: the diameter of the electrode liquid return channel (24) is smaller than the radius of the electrode liquid outlet channel (23).

3. The apparatus of claim 1, wherein: the flushing pump (8) comprises a pump body and a control valve; the suction pump (9) comprises a pump body, a control valve and a filter.

4. A method of processing using the apparatus of any of claims 1 to 3, the method comprising:

preparing for electric arc machining, namely fixing a workpiece material on a workbench of a machine tool in an insulating manner, fixing a tool electrode (2) on a rotating main shaft (1), and fixedly connecting the rotating main shaft (1) with a main shaft of the machine tool and keeping the rotating main shaft insulated; connecting the workpiece material and the tool electrode (2) to two poles of a discharge power supply respectively; then the electrode liquid return channel (24) is communicated with the suction pump (9) through a liquid return loop channel (11) arranged on the rotating main shaft (1) and a liquid return hole arranged on the main shaft shell (5); setting a discharge gap between a workpiece material and a tool electrode (2) by a machine tool servo system;

high-speed electric arc machining, wherein medium liquid in a liquid storage tank (10) reaches a high-pressure state through a flushing pump (8) and flows through an electrode liquid outlet channel (23) of a rotating main shaft (1) and a tool electrode (2) to provide high-pressure internal flushing liquid for a machining area; the high-pressure internal flushing liquid realizes hydrodynamic arc breaking and quickly flushes the eroded particles away from the processing area; under the negative pressure environment of a machining gap, medium liquid carrying with corrosion removal particles flows through an electrode liquid return channel (24), a liquid return loop channel (11) on a rotating main shaft (1) and a liquid return hole on a main shaft shell (5) and is filtered by a suction pump (9) and pumped back to a machine tool liquid storage tank (10) to form a liquid supply circulation system;

after the machining is finished and the discharging is stopped, the main shaft of the machine tool stops rotating, the tool electrode (2) stays at the machining finishing position for a short time, and the liquid medium with metal corrosion particles is fully pumped away by a suction pump (9); and then the machine tool is lifted to a safe position through servo motion of the machine tool, and the machine tool is stopped.

5. The method of claim 4, wherein: the discharge power supply adopts a periodic pulse power supply, the voltage value is 30-120V, the peak current is 50-10000A, and the range of the pulse width and the pulse interval is 2-20000 mus.

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