CN209773659U - Plane electric spark processing device - Google Patents

Abstract

the utility model discloses a plane spark-erosion treatment device, include: the rotary electrode comprises a rotatable disk-shaped electrode seat and electrodes which are uniformly distributed on the electrode seat along the shape of a ring; the output end of the pulse power supply is electrically connected with the electrode and is used for outputting instantaneous discharge electric energy to the electrode; in the rotating process of the rotating electrode, the electrode of the rotating electrode sequentially approaches and contacts the workpiece, and discharges electricity to the surface of the workpiece, so that a strengthening point is formed on the surface of the workpiece; the device utilizes the gas medium between the electrode and the surface of the workpiece to carry out instantaneous spark discharge, and converts electric energy into heat energy and energy in other forms, so that the metal surface layer generates physical, chemical and metallurgical changes, and the performances such as hardness, strength, wear resistance, corrosion resistance and the like of the surface of the workpiece are improved.

Description

Plane electric spark processing device

Technical Field

The utility model relates to a mechanical parts surface strengthening field, in particular to plane electric spark processing apparatus.

Background

With the development of industrial modernization and aerospace technologies, the requirements on the surface properties of various mechanical equipment parts are higher and higher. Some parts working under high speed, high temperature, high pressure and other conditions are always scrapped because of local surface abrasion. Therefore, how to improve the surface quality and performance of the parts to prolong the service life of the workpieces is a very important problem.

For example, the surface of parts such as a guide rail of a lathe, a rail turnout of a train and the like is subjected to high-pressure friction during working, and the surface is very easy to wear and lose efficacy, so that the processing precision of the lathe is reduced, and the train is not stable or even in dangerous conditions. Therefore, a plane electric spark processing device is needed to modify and strengthen the guide rail plane and the vehicle rail plane or perform certain on-line repair to improve the surface wear resistance of the guide rail plane and the vehicle rail plane, so as to achieve the purpose of prolonging the service life.

SUMMERY OF THE UTILITY MODEL

In view of the above, the present invention provides a planar electric spark processing apparatus, which utilizes a gas medium between an electrode and a workpiece surface to perform an instantaneous spark discharge, and converts electric energy into heat energy and other forms of energy, so as to generate physical, chemical and metallurgical changes on a metal surface layer, thereby improving the hardness, strength, wear resistance, corrosion resistance and other properties of the workpiece surface.

the plane electric spark processing device comprises: the rotary electrode comprises a rotatable disk-shaped electrode seat and electrodes which are uniformly distributed on the electrode seat along the shape of a ring; the output end of the pulse power supply is electrically connected with the electrode and is used for outputting instantaneous discharge electric energy to the electrode; the pulse electrode adopts an RC pulse generator, as shown in figure 1, the pulse electrode comprises a direct current power supply, a current-limiting resistor and an energy storage capacitor, and the direct current power supply, the current-limiting resistor and the energy storage capacitor are sequentially and electrically connected to form a charging loop; the capacitor, the electrode and the workpiece are sequentially and electrically connected to form a discharge circuit, and in the rotating process of the rotating electrode, the electrode of the rotating electrode sequentially approaches and contacts the workpiece to discharge to the surface of the workpiece, so that a strengthening point is formed on the surface of the workpiece. As shown in fig. 6, 3 threaded holes are circumferentially and uniformly distributed on the disc-shaped electrode holder for fixedly mounting three electrodes; when the workpiece is strengthened, the surface of the workpiece to be strengthened is positioned on the distribution circle circumference of the motor, the electrode is connected with the positive electrode of the pulse power supply, the workpiece is connected with the negative electrode, the discharge frequency of the pulse power supply is determined by the electrode rotating speed and the number of the electrodes, one discharge is ensured to occur when the electrode rotates to be in contact with the workpiece each time, the discharge strengthening process of each time is shown in figure 2, the motor rotates to drive the electrode on the motor base to rotate, when the electrode does not contact the workpiece yet, the power supply E charges the capacitor C through the current limiting resistor R, and the state between the electrode and the workpiece is shown in figure 2a (wherein an arrow indicates that the electrode is close to or far away from. When the electrode rotates to move towards the workpiece and approaches the workpiece infinitely, a discharge circuit is formed into a path, a discharge current instantly flows in a spark discharge path and a contacted micro-area, the current density is as high as 105-106A/cm 2, and the discharge time is only a few microseconds to a few milliseconds. Due to the high temporal and spatial concentration of the discharge energy, a high temperature of 5000-15000 ℃ is generated in the micro-discharge area, causing the matrix of this area to sputter towards the surrounding medium, as shown in fig. 2 b. The electrode continues to approach the workpiece, forcing the material of the electrode and workpiece together, as shown in fig. 2 c. Since the current density in the contact region is drastically reduced and the contact resistance is remarkably reduced due to the enlargement of the contact area and the reduction of the discharge current, the electric energy does not generate heat in the contact portion. In contrast, the partially melted material is rapidly cooled to solidify due to the cooling action of the air medium and the metallic workpiece substrate. The condensed material then detaches from the electrode and adheres to the workpiece, becoming a strengthened spot on the workpiece surface. Meanwhile, the electrode rotates, so that the electrode is separated from the workpiece, the discharge loop is disconnected, and the power supply recharges the capacitor C, which is the primary charging and discharging process of the transient electric energy strengthening equipment. The next electrode repeats the charging and discharging process and continuously moves the workpiece, so that the contact position changes, the strengthening points are mutually overlapped and fused, and a strengthening layer is formed on the surface of the workpiece. The charging and discharging period is very short, the number of electrodes and the rotating speed of the electrodes are fully designed, and the strengthening efficiency can be improved.

Further, the electrode holder is driven to rotate by a motor; an elastic coupling is arranged between the rotating shaft of the electrode and the electrode seat, and the distance between the electrode and the surface of a workpiece can be adjusted through the elastic coupling so as to prevent the electrode and the workpiece from generating rigid collision.

Furthermore, the resistance value of the current-limiting resistor and the capacitance value of the capacitor can be adjusted; the discharging current is controlled by adjusting the resistance value of the resistor in the charging circuit, and the discharging energy is controlled by adjusting the gear of the capacitor. Thus, the change from large current large capacitance to small current small capacitance can form different combination of standards, thereby controlling the strengthening efficiency and the surface roughness of the strengthening layer. Generally, a rough standard (large current and large capacitance) is used for treatment, and then a fine standard (small current and small capacitance) is used for adjusting the surface roughness.

furthermore, the electrode is fixed in the motor cabinet with the detachable mode, is equipped with the double-screw bolt with the screw complex of motor cabinet on the electrode, and the thickness of electrode is adjusted as required to the installation dismantlement electrode of being convenient for.

Furthermore, the workpiece is clamped on a workbench of the milling machine, so that the strengthening position of the workpiece can be accurately controlled, and the moving speed of the strengthening point is ensured to be uniform.

Further, the power of motor loops through elastic coupling, transition transmission shaft and transition transmission sleeve with power transmission to electrode holder, as shown in fig. 3-6, the utility model discloses a motor is speed governing micro motor, it includes motor element and US-52 speed regulator constitution, can realize the regulation of motor shaft rotational speed, elastic coupling adopts the plum blossom elastic coupling JM20 of the accurate machinery limited company production of Jinqiantong of Jinan, its input rotates fixed connection with the motor, the front end fixed connection of output and transition transmission shaft, the rear end of transition transmission shaft is equipped with the stud section, transition transmission sleeve's center be equipped with this stud section complex central screw hole, transition transmission sleeve's outer wall is equipped with the external screw thread, the screw hole at electrode holder middle part can mutually support with the external screw thread on the transition transmission sleeve.

the utility model has the advantages that:

1. the spark strengthening equipment is carried out in air, and does not need special and complicated processing devices and facilities, such as a vacuum system or a special container, so that the process equipment is simple. The electric spark strengthening machine also has no mechanical mechanisms such as a transmission mechanism, a workbench and the like, is convenient to carry, flexible to use, low in equipment investment and operation cost, and can be widely popularized and used.

2. It can be used for local strengthening of the surface of the part and strengthening of a plane or a curved surface with a general geometric shape. For example, the cutter, the die and the mechanical parts can strengthen the cutting edge and the part which is easy to wear, thus achieving the purpose of improving the hardness and the wear resistance and having wide application range.

3. The workpiece is not annealed or thermally deformed after the treatment. Although the material can be melted at the discharge instant to reach a high temperature for vaporization, the discharge time is short and the area of the discharge point is small, so that the thermal action of the discharge occurs only in a small area on the surface of the workpiece. As for the whole workpiece, the workpiece is still in a normal temperature state or the temperature rise is low, the workpiece cannot be annealed or thermally deformed, and the workpiece can be repaired on line.

4. The strengthening layer is firmly combined with the substrate and can not be separated. The transient electric energy strengthening layer is a new alloy layer formed by re-alloying the electrode and the workpiece material under the condition of instantaneous high temperature and high pressure of discharge. The electrode is not simply coated and stacked, but an alloy layer and a diffusion layer formed by the electrode and base material elements can be used for repairing large loads and harsh environments.

5. The electrode material can be freely selected for different uses. For strengthening the cutter, the die and the like with the aim of improving the wear resistance, YG and YW hard alloy can be selected as an electrode to form a strengthening layer with high hardness, high wear resistance and corrosion resistance; when the worn parts of machine parts are repaired, carbon steel, red copper, brass and other materials can be used as electrodes, and the sources of the materials are wide and the consumption of the materials is low.

6. the thickness and the surface roughness of the strengthening layer are related to the process factors such as the current, the electric capacity and the like of the pulse power supply, the strengthening time and the like, so that different process effects can be obtained by controlling the electric parameters, the strengthening time and the like.

7. The repair method can be used for site construction without disassembling repaired parts, and time is saved. The reinforced layer can be reinforced for many times, and the cost of reinforced repair is lower than that of replacement of parts.

8. The strengthening can be carried out under the condition of room temperature, and the strengthening method can show the superiority on repairing local and small-amount damage workpieces with poor weldability and quenching states.

9. The machining allowance after electric spark strengthening is very small, only manual tools such as oilstones, files and the like are needed for bench work repairing, and the repairing time is shortened;

10. the operation method is easy to master, and operators with high technical grade are not needed;

11. The electric spark strengthening equipment is operated, toxic and unpleasant gas, liquid and solid wastes are not generated, the noise is low, and the environmental pollution is not caused.

drawings

The invention will be further described with reference to the following figures and examples:

FIG. 1 is a schematic diagram of the present invention;

FIG. 2 is a schematic view of the electrode state during the strengthening process using the present invention;

Fig. 3 is a schematic view of a drive chain of the rotary electrode of the present invention;

fig. 4 is a schematic view of a transition transmission shaft according to the present invention;

fig. 5 is a schematic view of the transition transmission sleeve of the present invention;

Fig. 6 is a schematic view of an electrode holder according to the present invention;

FIG. 7 is an SEM photograph of the surface topography of the spark-hardenable layer of the strengthened workpiece;

FIG. 8 is a plot of microhardness versus depth for three material reinforced layers;

FIG. 9 is a graph showing the wear resistance curves of the lower sample when the lower sample is a strengthened and non-strengthened U70MnSi steel, and the upper sample is non-strengthened GCr15 rolling wear.

Detailed Description

Fig. 1 is a schematic view of the present invention, and as shown in the figure, the planar electric spark processing apparatus of the present embodiment includes: the rotary electrode comprises a rotatable disk-shaped electrode seat 7 and electrodes 6 which are uniformly distributed on the electrode seat 7 along the ring shape; the electrode holder 7 is driven to rotate by a motor 8, the motor 8 is powered by an alternating current power supply 1, and the power of the motor is transmitted to the electrode holder 7 through an elastic coupling 9, a transition transmission shaft 10 and a transition transmission sleeve 11 in sequence;

the output end of the pulse power supply 2 is electrically connected with the electrode 6 and is used for outputting instantaneous discharge electric energy to the electrode 6; the pulse power supply 2 comprises a direct current power supply, a current-limiting resistor 3 and an energy-storage capacitor 4, and the direct current power supply, the current-limiting resistor 3 and the energy-storage capacitor 4 are sequentially and electrically connected to form a charging loop; the capacitor 4, the electrode 6 and the workpiece 5 are sequentially electrically connected to form a discharge circuit; in the rotating process of the rotating electrode, the electrodes 6 of the rotating electrode sequentially approach and contact the workpiece 5, and discharge electricity to the surface of the workpiece 5, so that strengthening points are formed on the surface of the workpiece 5.

In this embodiment, U70MnSi is used as the substrate material of the workpiece 5, YG-8 (92% WC, 8% Co) is used as the electrode 6, and the performance test after the strengthening treatment is as follows:

1) Surface topography

The electric spark surface strengthening layer is composed of dense strengthening points and discharge pits, as shown in fig. 7. The surface is orange peel, which is advantageous for improving the wear resistance of the surface of the workpiece 5. Since the larger the energy of a single discharge pulse is, the larger the size of the molten metal droplet is, the larger the pits and strengthening points are formed, and the larger the surface roughness after the electric spark is strengthened, the reasonable selection of electrical parameters is necessary, and not only the wear resistance of the surface of the workpiece 5 can be improved, but also the surface roughness of the strengthened layer can be controlled to be small.

From the documents [ Tang D P, GaO Q, Jiang X Y, Structure and Performance and bonding of titanium carbide surface Technology,2004(4): P13-15 ], it is known that under the same conditions of the workpiece 5, the electrode 6 and the strengthening medium, the energy of the discharge pulse is increased, the surface roughness of the strengthening layer is increased, but the thickness of the strengthening layer is also increased; when the energy of the discharge pulse is reduced, the surface roughness becomes small, and the thickness of the strengthening layer is also thin. To meet the requirement of reducing the surface roughness, a method of limiting the energy of a single pulse discharge may be adopted. However, when the energy of a single pulse is reduced, the thickness and the strengthening efficiency of the strengthening layer are reduced, so that a certain thickness of the strengthening layer is obtained, and the smaller roughness and the higher production efficiency are maintained, and the reasonable process method comprises the following steps: the large-scale reinforcement is adopted firstly, the thickness of the reinforcement layer is ensured, the production efficiency is improved, and then the electrical gauge is gradually reduced to repair the surface, so that the purpose of reducing the surface roughness is achieved.

2) Surface hardness

FIG. 8 is a graph of microhardness as a function of distance from a strengthened surface. As can be seen from the figure, the hardness of the strengthening layer (generally white and bright in the photo) is significantly higher than that of the matrix, and the hardness of the heat affected zone is significantly reduced. The structure of the bright layer contains high-hardness carbide (such as Fe7C3 and Cr23C6), nitride (such as Fe2N, Cr2N and BN) and alloy elements, so that the hardness of the bright layer is very high. The carbon content and the hardness of the carbide, nitride, or the like are reduced in a gradient manner in the depth direction of the reinforcing layer, and the hardness of the reinforcing layer is reduced in a gradient manner in the depth direction.

From the above analysis, it can be seen that the electric spark surface strengthening is not a simple plating process, but rather the electrode 6, elements in the sample and various ions ionized in the air (mainly nitrogen ions) are diffused, alloyed and nitrided, and a series of high-hardness and wear-resistant phases with special structures are generated in the strengthening layer.

3) wear resistance

As shown in fig. 9, rolling wear test tests were conducted on the reinforced and unreinforced U70MnSi steels as the lower samples and the GCr15 as the upper samples, respectively, and it can be seen that the wear resistance of the reinforced U70MnSi steel samples was significantly increased as compared with the unreinforced U70MnSi steel samples.

finally, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the present invention can be modified or replaced by other means without departing from the spirit and scope of the present invention, which should be construed as limited only by the appended claims.

Claims (7)

1. a planar electric discharge machining apparatus, comprising:

The rotary electrode comprises a rotatable disk-shaped electrode seat and electrodes which are uniformly distributed on the electrode seat along the shape of a ring;

The output end of the pulse power supply is electrically connected with the electrode and is used for outputting instantaneous discharge electric energy to the electrode;

In the rotating process of the rotating electrode, the electrode of the rotating electrode sequentially approaches and contacts the workpiece, and discharges electricity to the surface of the workpiece, so that a strengthening point is formed on the surface of the workpiece.

2. A planar electric discharge machining apparatus according to claim 1, characterized in that: the pulse power supply comprises a direct current power supply, a current-limiting resistor and an energy-storage capacitor, wherein the direct current power supply, the current-limiting resistor and the energy-storage capacitor are sequentially and electrically connected to form a charging loop; the capacitor, the electrode and the workpiece are electrically connected in sequence to form a discharge circuit.

3. A planar electric discharge machining apparatus according to claim 2, characterized in that: the electrode holder is driven to rotate by a motor; an elastic coupling is arranged between the rotating shaft of the electrode and the electrode seat.

4. A planar electric discharge machining apparatus according to claim 3, characterized in that: the resistance value of the current-limiting resistor and the capacitance value of the capacitor can be adjusted.

5. A planar electric discharge machining apparatus according to claim 4, characterized in that: the electrode is detachably fixed to the motor base.

6. A planar electric discharge machining apparatus according to claim 5, characterized in that: the workpiece is clamped on a workbench of a milling machine.

7. A planar electric discharge machining apparatus according to claim 6, characterized in that: and the power of the motor is transmitted to the electrode holder through the elastic coupling, the transition transmission shaft and the transition transmission sleeve in sequence.