Electrolytic plasma thermal processing apparatus

Abstract

The application relates to an electrolytic plasma heat treatment device which is composed of an electrolyte, an electrolyte supply system and a voltage adjusting system; the electrolyte supply system can adjust the flow of the electrolyte so that the electrolyte is uniformly supplied to the surface of a workpiece to be treated in the form of a jet; the voltage adjusting system comprises a sensor, an automatic control system and a power supply module with preset high, medium and low voltages, the sensor detects the surface temperature of the heat treatment workpiece and feeds back to the automatic control system, the automatic control system automatically controls the power supply to switch among the high, medium and low voltages according to the temperature data, heat cycle treatment of the surface of the workpiece is realized, and a hardened layer with low stress level and high impact toughness can be obtained. In addition, by adjusting the values of the high, medium and low voltages, a heat treatment layer with alternating hard structure and soft structure can be obtained, and the stress can be further reduced and the impact toughness can be improved.

Description

Technical Field

[0001] This invention belongs to the field of surface heat treatment technology for metals and alloys, and particularly relates to an electrolytic plasma heat treatment device. Background Technology

[0002] Comparative Technology 1: Steel Heat Treatment Method and Equipment [Russian Patent No. 1064629, Inventors: Andreeva N.A., Belyakova TD., Mikhnev MM., IPC: C21D1 / 74. May 20, 1997]. This invention relates to a technique for heat treating the surface of metal or alloy workpieces using a high-density energy source. It can be used for surface hardening of cutting tools and other tools (saw teeth, taps, screwdrivers, chisels, etc.), as well as for annealing, melting, and welding of metal or alloy workpieces. It can also be used to excite plasma in various plasma devices. The anode is placed at the bottom of an electrolytic cell containing an electrolyte, with the workpiece as the cathode. Before treatment, the workpiece surface is brought into contact with the electrolyte. Then, an electric current is applied between the cathode and anode, stimulating plasma discharge at the contact point between the workpiece surface and the electrolyte. This heats the workpiece surface to the quenching temperature. Afterward, the power is cut off, and the workpiece is immersed in the electrolyte for quenching.

[0003] Comparative Technology 2: Method and Equipment for Surface Heat Treatment [Russian Patent 2077611, Inventors: Steblyanko V.L, Ryabkov VM, IPC: C25D5 / 00.2, April 20, 1997]. This patent proposes a surface heat treatment method in which an anode and a workpiece (cathode) are placed in an electrolyte, installed parallel to each other at a certain distance, with an electrolyte channel between them connected to a pressure pipeline supplying the electrolyte. An element is installed between the anode and the workpiece, using this element and the channel to uniformly supply the electrolyte to the workpiece surface, and heat treatment is performed on the workpiece surface by discharge. The anode is made of an inert conductive material. When heat treating large planar workpieces, they can be placed between two parallel anodes to treat both sides of the workpiece simultaneously. The equipment for surface heat treatment includes an anode, an electrolyte guiding element, and an electrolyte collection and purification system.

[0004] Comparative techniques 1 and 2 propose equipment and heat treatment methods. Their advantages include high heating rates, which improve the surface hardening efficiency of the workpiece. However, their disadvantages include the inability to control the workpiece surface temperature and the inability to execute corresponding heat treatment processes based on the characteristics of the workpiece material. Due to their high heating and cooling rates, the hardened layer obtained by these methods is typically in a state of high stress and low impact toughness, thus failing to achieve a deep hardened layer on the workpiece surface. Therefore, their application in the heat treatment of high-carbon tool steel is limited.

[0005] Comparative technology 3 (prototype technology) is the closest to the technology proposed in this invention. It is a heat treatment device that performs localized thermal cycling on a workpiece in an electrolyte [USSR Patent Nos. 931760, 1235226, Inventor: Yu.N.Tyurin, C21D1 / 44, 1976, 1984]. The device proposed in this patent achieves periodic heating and cooling by alternately increasing and decreasing the voltage between the electrolyte and the workpiece surface, which can significantly improve the physical and mechanical properties of the workpiece. The voltage difference between low and high voltage is 50–100 V, which allows for variations in the heating intensity of the workpiece surface. At low voltage, the discharge energy density between the workpiece surface and the electrolyte decreases, the formed plasma layer weakens, resulting in reduced surface heat and a lower temperature. At high voltage, the discharge energy density between the workpiece surface and the electrolyte increases, and the workpiece surface temperature rises.

[0006] The advantage of technology 3 (prototype technology) is that it enables periodic heating and cooling of the workpiece, thereby significantly improving its physical and mechanical properties. Its disadvantages are: the equipment and technology lack automated temperature control technology for the workpiece, lack adjustable heat treatment modes and control methods, and cannot automatically control the surface temperature, thus limiting its application range. Furthermore, the equipment cannot adjust the heating process by changing the electrolyte conductivity. Summary of the Invention

[0007] This invention provides an electrolytic plasma heat treatment device, which establishes a system for monitoring and controlling the surface temperature of the heated workpiece during the heating-cooling-quenching process, thereby improving the heating efficiency of the workpiece surface and achieving automatic temperature control. It also proposes to optimize the electrolyte flow by using a hydrodynamic component, thereby increasing the conductivity of the electrolyte.

[0008] To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0009] An electrolytic plasma heat treatment device comprises an electrolyte, an electrolyte supply system, and a voltage regulation system. The electrolyte supply system includes a cylinder, a piston rod, a platform, pipes, mounting holes, orifices, a heater metal shell, and an insulating shell. The voltage regulation system includes a power supply, a first wire, a second wire, an automatic control system, an analog system, a shielding wire, a sensor, a sensor shell, and an anode. The cylinder is fixed on the platform, and a piston rod is assembled inside the cylinder. The bottom of the piston rod has a mounting hole, and the top of the piston rod seals and fixes the heater metal shell. An orifice is made on the contact surface between the piston rod and the heater metal shell. An anode with a through hole is fixed on the top of the heater metal shell. The sensor shell passes through the piston rod, the heater metal shell, and the anode and is fixed to each of them. A sensor is installed inside the sensor shell. The insulating shell is placed above the heater metal shell, and the two are in sealed contact. The insulating shell forms a conical cavity with an open top. The sensor is perpendicular to the opening plane of the insulating shell and coaxial with the conical insulating shell. The channel axis in the electrode intersects the axis of the open top of the electrolyte. The first wire connects the workpiece to the power supply, the second wire connects the anode to the power supply, and the shielding wire connects the sensor to the analog system.

[0010] In a preferred embodiment of the present invention, the workpiece is located on one side of the insulating shell. Electrolyte is supplied to the cylinder through a pipe. The piston rod moves out of the cylinder and raises the heater until the gap dimension δ between the workpiece surface and the insulating shell of the heater reaches the predetermined requirement. Electrolyte enters the groove of the metal shell of the heater through the hole, and then enters the conical cavity formed by the insulating shell in the form of a jet through the through hole of the anode. The power supply applies voltage to the anode and the workpiece through the first wire and the second wire. The electrolyte jet passes through the anode and the workpiece, forming a thin vapor layer and local high pressure at the boundary between the workpiece and the electrolyte jet, which excites plasma discharge and achieves the effect of local heat treatment on the surface of the workpiece, forming a hardened layer. The sensor measures the temperature of the heated surface of the workpiece in a non-contact manner and provides the temperature data to the simulation system through the shielded wire. After being converted by the simulation system, it is provided to the automatic control system. The automatic control system provides control signals to the power supply according to the temperature data, adjusts the preset voltage, and adjusts the heat treatment mode in real time.

[0011] In a preferred embodiment of the present invention, the ratio of the anode conductive cross-sectional area to the cross-sectional area of ​​the insulating shell is 5 to 10.

[0012] As a preferred embodiment of the present invention, the heater housing is made of stainless steel and the insulating housing is made of fluoroplastic.

[0013] As a preferred embodiment of the present invention, the sensor for measuring the surface temperature of the workpiece is made of a photoresistor.

[0014] As a preferred embodiment of the present invention, when performing heat treatment using the electrolytic plasma heat treatment equipment proposed in this invention, the gap dimension δ between the workpiece surface and the insulating shell of the heater is a function of the electrolyte pressure, the piston rod diameter d, the diameter D of the cross-section of the insulating shell of the heater, and the ratio of the cross-sectional area of ​​the bottom mounting hole of the piston rod to the bottom hole of the heater.

[0015] In a preferred embodiment of the present invention, the sensor is embedded 10-20 mm below the electrolyte during the heat treatment process.

[0016] In a preferred embodiment of the present invention, the mounting hole is used to control the flow rate of the electrolyte.

[0017] In a preferred embodiment of the present invention, the orifice is used to control the flow rate of the electrolyte.

[0018] As a preferred embodiment of the present invention, the automatic control system provides a control signal to the power supply based on temperature data. When adjusting the preset voltage, the high voltage setting range is 280-340V, the medium voltage setting range is 180-240V, and the low voltage setting range is 20-40V.

[0019] As a preferred embodiment of the present invention, the method of using the electrolytic plasma heat treatment equipment involves using a sensor to measure the surface temperature of the workpiece, heating under high voltage, and when the surface temperature is 100-200°C higher than the Ac3 temperature of the workpiece material, the automatic control system controls the power supply to reduce the voltage to medium voltage. When the surface temperature is 100-200°C lower than the Ac3 temperature of the workpiece material, the automatic control system controls the power supply to increase the voltage to high voltage. The voltage is cyclically increased and decreased until the depth of the hardened layer on the workpiece surface reaches the predetermined requirement, at which point the automatic control system controls the power supply to reduce the voltage to low voltage.

[0020] As a preferred embodiment of the present invention, the method of using the electrolytic plasma heat treatment equipment involves using a sensor to measure the surface temperature of the workpiece. During high-voltage heat treatment, when the surface temperature of the workpiece reaches the melting point, the automatic control system controls the power supply to reduce the voltage to a medium voltage. When the surface temperature of the workpiece drops to the Curie temperature, the automatic control system controls the power supply to increase the voltage to a high voltage. The voltage is cyclically increased and decreased until the depth of the hardened layer on the workpiece surface reaches the predetermined requirement, at which point the automatic control system controls the power supply to reduce the voltage to a low voltage.

[0021] As a preferred embodiment of the present invention, in the method of using the electrolytic plasma heat treatment equipment, when the heat cycle reaches the design requirements, the automatic control system controls the power supply to decrease from high voltage to low voltage.

[0022] As a preferred embodiment of the present invention, in the method of using the electrolytic plasma heat treatment equipment, when the heat cycle reaches the design requirements, the automatic control system controls the power supply to reduce from medium voltage to low voltage.

[0023] As a preferred embodiment of the present invention, the method of using the electrolytic plasma heat treatment equipment is to turn off the power supply to achieve quenching when the surface temperature is higher than the Ac3 temperature of the workpiece material.

[0024] The beneficial effects of this invention are:

[0025] 1. The equipment described in this invention has a simple structure and ingenious design, and can form a heat treatment layer with a depth of 5 to 15 mm on the surface of the workpiece with high hardness and high plasticity.

[0026] 2. The equipment described in this invention ensures a high-quality heat treatment process and forms a hardened layer structure with low stress levels. During the heat treatment process, the equipment can adjust the heat treatment mode in real time according to the workpiece surface temperature, thus enabling the hardened layer to form layer by layer. This ensures multiple refinements and homogenization of austenite grains before quenching, and also yields a microstructure with alternating soft and hard layers, reducing stress and improving the impact toughness of the workpiece under high hardness.

[0027] 3. Compared with the prototype technology, the voltage regulation system of the device described in this invention ensures complete automation of the workpiece heat treatment mode and heat treatment quality control.

[0028] 4. In the device described in this invention, the ratio of the anode conductive cross-sectional area to the cross-sectional area of ​​the insulating shell is 5 to 10. This feature can significantly improve the reliability of the heat treatment equipment and enhance the efficiency of heating and cooling.

[0029] 5. In the device described in this invention, the measuring axis of the sensor is perpendicular to the open section of the insulating shell, the electrolyte is supplied through the channel of the anode, and the sensor is placed 10-20mm below the electrolyte layer, which can ensure the stability and efficiency of the measurement process.

[0030] 6. The heat treatment equipment and method described in this invention are characterized by being eco-friendly and resource-saving, and when applied to the industrial field, they also have energy-saving effects. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the electrolytic plasma heat treatment equipment provided by the present invention.

[0032] Figure 2 This invention provides an electrolytic plasma heat treatment equipment component.

[0033] Figure 3 This is a photograph of the localized surface hardening of a workpiece using the electrolytic plasma heat treatment equipment provided by this invention.

[0034] Figure 4 The present invention provides an electrolytic plasma heat treatment device and the workpiece it processes.

[0035] Figure 5 The electrolytic plasma heat treatment equipment provided by this invention is used to heat treat workpieces.

[0036] Figure 6 The effects of heat treatment time t and voltage U on the surface hardening depth and hardness of carbon steel workpieces with a carbon content of 0.5%.

[0037] In the attached diagram: 1. Workpiece; 2. Hardened layer; 3. Gap; 4. Power supply; 5. First wire; 6. Second wire; 7. Automatic control system; 8. Simulation system; 9. Shielded wire; 10. Cylinder; 11. Piston rod; 12. Platform; 13. Pipe; 14. Mounting hole; 15. Sensor; 16. Sensor housing; 17. Hole; 18. Heater metal housing; 19. Anode; 20. Insulating housing; 20. Distance L from the sensor to the cross-section of the insulating housing of the heater; δ. Gap between the workpiece surface and the insulating housing of the heater; D. Diameter D of the cross-section of the insulating housing of the heater; d. Piston rod diameter.

[0038] Appendix Figure 6 In the diagram: U1 represents high voltage; U2 represents medium voltage; and t represents heat treatment time. Detailed Implementation

[0039] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] An electrolytic plasma heat treatment device, the specific implementation of which is as follows:

[0042] like Figures 1-5As shown, the electrolytic plasma heat treatment equipment proposed in this invention consists of an electrolyte, an electrolyte supply system, and a voltage regulation system. The electrolyte supply system includes a cylinder 10, a piston rod 11, a platform 12, a pipe 13, mounting holes 14 and 17, a heater metal shell 18, and an insulating shell 20. The voltage regulation system includes a power supply 4, a first wire 5, a second wire 6, an automatic control system 7, an analog system 8, a shielding wire 9, a sensor 15, a sensor shell 16, and an anode 19. The cylinder 10 is fixed on the platform 12, and the piston rod 11 is assembled inside the cylinder 10. The bottom of the piston rod 11 has a mounting hole 14, and the top of the piston rod 11 seals and fixes the heater metal shell 18. A hole 17 is opened on the contact surface between the piston rod 11 and the heater metal shell 18. An anode 19 with a through hole is fixed on the top of the heater metal shell 18. The sensor shell 16 passes through the piston rod 11, the heater metal shell 18, and the anode 19 and is fixed to each of them respectively. The sensor 15 is installed inside the sensor shell 16. The insulating shell 20... The electrode is placed above the metal housing 18 of the heater, and the two are in sealed contact. The insulating housing 20 forms a conical cavity with an open top. The sensor 15 is perpendicular to the opening plane of the insulating housing 20 and coaxial with the conical insulating housing 20. The channel axis in the electrode intersects with the axis of the open top of the electrolyte, so that a thin vapor layer and local high pressure are formed at the boundary between the workpiece 1 and the electrolyte jet, which excites plasma discharge and achieves the effect of local heat treatment on the surface of the workpiece 1. The first wire 5 connects the workpiece 1 to the power supply 4, the second wire 6 connects the anode 19 to the power supply 4, and the shield wire 9 connects the sensor 15 to the analog system 8.

[0043] The method for heat-treating a localized area of ​​workpiece 1 using this electrolytic plasma heat treatment equipment is as follows: Workpiece 1 is located on one side of the insulating shell 18. Electrolyte is supplied to cylinder 10 through pipe 13. Piston rod 11 moves out of cylinder 10 and raises the heater until the gap 3 δ between the surface of workpiece 1 and the insulating shell 20 of the heater reaches the predetermined requirement. Electrolyte enters the groove of the metal shell 18 of the heater through hole 17, and then enters the conical cavity formed by the insulating shell 20 in the form of a jet through the through hole of anode 19. Power supply 4 connects the anode 19 and the workpiece 1 through the first wire 5 and the second wire 6. When a voltage is applied to workpiece 1, an electrolyte jet is energized between anode 19 and workpiece 1, forming a thin vapor layer and local high pressure at the boundary between workpiece 1 and electrolyte jet, which excites plasma discharge, achieving the effect of local heat treatment on the surface of workpiece 1 and forming a hardened layer 2. During the heat treatment process, sensor 15 measures the temperature of the heated surface of workpiece 1 in a non-contact manner and provides this temperature to simulation system 8 through shielded wire 9. After being converted by simulation system 8, the temperature is provided to automatic control system 7. Automatic control system 7 provides control signals to power supply 4 based on temperature data, adjusts the preset voltage, and adjusts the heat treatment mode in real time.

[0044] In the electrolytic plasma heat treatment equipment proposed in this invention, the ratio of the conductive cross-sectional area of ​​the anode 19 to the cross-sectional area of ​​the insulating shell 20 is 5 to 10.

[0045] In the electrolytic plasma heat treatment equipment proposed in this invention, the heater shell 18 is made of stainless steel, and the insulating shell 20 is made of fluoroplastic.

[0046] The sensor 15 used to measure the temperature of the heated surface of the workpiece 1 in the electrolytic plasma heat treatment equipment proposed in this invention is made of a photoresistor.

[0047] When heat-treating workpiece 1 using the electrolytic plasma heat treatment equipment proposed in this invention, the gap 3 δ between the surface of workpiece 1 and the insulating shell 20 of the heater is a function of the electrolyte pressure, the piston rod diameter d, the diameter D of the cross-section of the insulating shell 20 of the heater, and the ratio of the cross-sectional areas of the bottom mounting hole 14 of the piston rod 11 and the bottom hole 17 of the heater.

[0048] When heat treating workpiece 1 using the electrolytic plasma heat treatment equipment proposed in this invention, sensor 15 is embedded 10-20 mm below the electrolyte.

[0049] When heat treating workpiece 1 using the electrolytic plasma heat treatment equipment proposed in this invention, the mounting hole 14 can control the flow rate of the electrolyte; specifically, a flow control valve is installed in the mounting hole 14, and the flow rate of the electrolyte is controlled by the flow control valve.

[0050] When heat-treating workpiece 1 using the electrolytic plasma heat treatment equipment proposed in this invention, the flow rate of the electrolyte can be controlled by the orifice 17. Specifically, a flow control valve is installed inside the orifice 17, and the flow rate of the electrolyte is controlled by the flow control valve.

[0051] The automatic control system 7 provides control signals to the power supply 4 based on temperature data. When adjusting the preset voltage, the high voltage setting range is 280-340V, the medium voltage setting range is 180-240V, and the low voltage setting range is 20-40V.

[0052] When heat-treating workpiece 1 using the electrolytic plasma heat treatment equipment proposed in this invention, sensor 15 measures the surface temperature of workpiece 1. The temperature is increased under high voltage. When the surface temperature is 100-200°C higher than the workpiece material Ac3 temperature, the automatic control system 7 controls the power supply 4 to reduce the voltage to medium voltage. When the surface temperature is 100-200°C lower than the workpiece material Ac3 temperature, the automatic control system 7 controls the power supply 4 to increase the voltage to high voltage. The voltage is increased and decreased in a cycle until the depth of the hardened layer 2 on the surface of workpiece 1 reaches the predetermined requirement. Then, the automatic control system 7 controls the power supply 4 to reduce the voltage to low voltage.

[0053] When heat-treating workpiece 1 using the electrolytic plasma heat treatment equipment proposed in this invention, sensor 15 is used to measure the surface temperature of workpiece 1. The temperature is increased under high voltage. When the surface temperature reaches the melting point, the automatic control system 7 controls the power supply 4 to reduce the voltage to medium voltage. When the surface temperature drops to the Curie temperature, the automatic control system 7 controls the power supply 4 to increase the voltage to high voltage. The voltage is increased and decreased in a cycle until the depth of the hardened layer 2 on the surface of workpiece 1 reaches the predetermined requirement. Then, the automatic control system 7 controls the power supply 4 to reduce the voltage to low voltage.

[0054] When the workpiece 1 is heat-treated using the electrolytic plasma heat treatment equipment proposed in this invention, and the heat cycle reaches the design requirements, the automatic control system can select to reduce the power supply from high voltage to low voltage.

[0055] When the workpiece 1 is heat-treated using the electrolytic plasma heat treatment equipment proposed in this invention, and the heat cycle reaches the design requirements, the automatic control system can select to reduce the power supply from medium voltage to low voltage.

[0056] When heat treating workpiece 1 using the electrolytic plasma heat treatment equipment proposed in this invention, if the surface temperature is higher than the workpiece material Ac3 temperature, quenching can be achieved by turning off the power supply 4.

[0057] Example 1:

[0058] Using an iron-based alloy with a carbon content of 0.5% as the workpiece, the heat treatment effect was tested using the equipment proposed in this invention. During the test, the electrode gap H was set to 35 mm. The power supply was set to a high voltage of 320V, a medium voltage of 200V, and a low voltage of 30V. The workpiece surface was heated under high voltage. When the workpiece surface temperature was 100–200°C higher than the Ac3 temperature, the voltage was reduced to medium voltage. When the workpiece surface temperature was 100–200°C lower than the Ac3 temperature, the voltage was increased back to high voltage. This hot-cold cycle was repeated for heat treatment. After 20 seconds, the voltage was reduced to low voltage to cool the workpiece, completing the heat treatment. The hardened layer depth and anodic corrosion were tested during the experiment when the ratio of the anode conductive cross-sectional area to the cross-sectional area of ​​the insulating shell was 1, 3, 5, 10, and 15, as shown in Table 1.

[0059] Table 1. Effect of the ratio of anodic conductive cross-sectional area to the area of ​​the plasma discharge zone on the workpiece surface on the workpiece hardening depth and anodic corrosion.

[0060]

[0061] Experimental results show that the optimal ratio of the anolyte conductive cross-sectional area to the plasma discharge area on the workpiece surface is 5–10. Decreasing this ratio leads to heat loss, shallow hardened layer depth, and anolyte corrosion. Increasing the ratio above 10 does not significantly improve the technical effect and also complicates the structure of the heat treatment equipment.

[0062] Example 2:

[0063] The workpiece was heat-treated using the same equipment and method as in Example 1. The electrode gap H was set to 35 mm. The workpiece surface was heated under high voltage. When the workpiece surface temperature was 100–200°C higher than the Ac3 temperature, the voltage was reduced to medium voltage. When the workpiece surface temperature was 100–200°C lower than the Ac3 temperature, the voltage was increased back to high voltage. This hot-cold cycle was repeated for heat treatment. After 20 seconds, the voltage was reduced to low voltage to cool the workpiece and complete the heat treatment. During heat treatment, the ratio of the anode conductive cross-sectional area to the cross-sectional area of ​​the insulating shell was set to 10. The effects of different high, medium, and low voltages on the depth and hardness of the heat-treated hardened layer were tested, as shown in Table 2. The high voltage test range was 240–360 V, the medium voltage test range was 140–250 V, and the low voltage test range was 10–60 V.

[0064] Table 2. Effects of variations in high voltage, low voltage, and cooling voltage on the depth and hardness of the heat-treated hardened layer.

[0065]

[0066] Experimental results show that the optimal voltage configuration between the anode and the workpiece surface is: high voltage: 300–340V, medium voltage: 200–240V, and low voltage: 20–40V. Voltages higher than the optimal configuration (high and medium voltages) can lead to surface overheating and / or plasma layer breakdown, while voltages lower than the optimal configuration can result in no heating or disruption of the heating mode. Low voltage affects the cooling rate; above the optimal low voltage range, a surface structure with low hardness and low stress levels is formed; below the optimal low voltage range, a structure with high stress levels, crack defects, and high hardness is formed. Cooling within the optimal low voltage range can form a surface structure with high hardness and sufficiently low stress levels.

[0067] Example 3:

[0068] The workpiece was heat-treated using the same equipment and method as in Example 1. The electrode gap H was set to 35 mm, the ratio of the anode conductive cross-sectional area to the cross-sectional area of ​​the insulating shell was set to 10, and the high, medium, and low voltages were all set within the optimal voltage configuration range. The workpiece surface was heated at high voltage. When the workpiece surface temperature was 100–200°C higher than the Ac3 temperature, the voltage was reduced to medium voltage. When the workpiece surface temperature was 100–200°C lower than the Ac3 temperature, the voltage was increased back to high voltage. This hot-cold cycle was repeated to perform the heat treatment. After 20 seconds, the voltage was reduced to low voltage to cool the workpiece and complete the heat treatment.

[0069] Experimental results show that the surface hardening layer obtained under these test conditions exhibits a hardness that fluctuates with depth, with a fluctuation range not exceeding 100 HV.

[0070] Example 4:

[0071] The workpiece was heat-treated using the same equipment and method as in Example 1. The electrode gap H was set to 35 mm, the ratio of the anode conductive cross-sectional area to the cross-sectional area of ​​the insulating shell was set to 10, and the high, medium, and low voltages were all set within the optimal voltage configuration range. The workpiece surface was heated at high voltage. When the workpiece surface temperature reached the workpiece melting point, the voltage was reduced to medium voltage. When the workpiece surface temperature equaled the Curie point temperature of the workpiece material, the voltage was increased back to high voltage. This hot-cold cycle was repeated to perform the heat treatment. After 20 seconds, the voltage was reduced to low voltage to cool the workpiece, completing the heat treatment.

[0072] Experimental results show that under these conditions of high heating and cooling rates, a layered surface hardened layer can be obtained, with multiple hard layers alternating with softer layers, and a hardness fluctuation range exceeding 200 HV. This alternating hard and soft surface heat treatment layer ensures stress release and improves the physical and mechanical properties of the product surface.

[0073] In the above embodiments, the method described in Embodiment 3 is applicable to the surface hardening treatment of high carbon alloy workpieces, and Embodiment 4 is applicable to the surface hardening treatment of low carbon steel.

[0074] Figure 6 The figure shows the relationship between the surface hardening depth and hardness of an iron-based alloy with a carbon content of 0.5% and the heating time t and voltage U. During high-voltage and medium-voltage cyclic treatment, with a treatment time of 15–70 s, 5–20 thermal cycles can be achieved, obtaining a wear-resistant hardened layer of 1–10 mm thickness. Cooling at a low voltage of 20–40 V can effectively prevent the formation of hardening cracks.

[0075] The electrolytic plasma heat treatment equipment proposed in this invention has an electrolyte jet system that ensures the wave shape on the surface of the electrolyte, and the waveform amplitude of the wave is 1 to 2 mm (which varies according to the amount of electrolyte consumed). The gap between the electrolyte and the workpiece is controlled at 0.1 to 2 mm. This ensures that plasma discharge is generated between the electrolyte and the workpiece, and also ensures that the intensity of the plasma layer current caused by the discharge is adjustable.

[0076] The electrolytic heat treatment equipment proposed in this invention can be widely used to achieve high-quality heat treatment of the surface of various alloy workpieces. The heat treatment technology based on the equipment proposed in this invention is stable and reliable.

[0077] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention; therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0078] Although this document uses numerous reference numerals from the figures: workpiece 1, hardened layer 2, gap 3, power supply 4, first wire 5, second wire 6, automatic control system 7, simulation system 8, shielding wire 9, cylinder 10, piston rod 11, platform 12, pipe 13; mounting hole 14, sensor 15, sensor housing 16, hole 17, heater metal housing 18, anode 19, insulating housing 20, distance L from the sensor to the cross-section of the insulating housing of the heater, gap δ between the workpiece surface and the insulating housing of the heater, diameter D of the cross-section of the insulating housing of the heater, piston rod diameter d, etc., the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would be contrary to the spirit of the invention.

Claims

1. An electrolytic plasma heat treatment apparatus, characterized in that: It consists of an electrolyte, an electrolyte supply system, and a voltage regulation system. The electrolyte supply system includes a cylinder (10), a piston rod (11), a platform (12), a pipe (13), a mounting hole (14), a hole (17), a heater metal shell (18), and an insulating shell (20). The voltage regulation system includes a power supply (4), a first wire (5), a second wire (6), an automatic control system (7), an analog system (8), a shielded wire (9), a sensor (15), a sensor shell (16), and an anode (19). The cylinder (10) is fixed on the platform (12), and the piston rod (11) is installed inside the cylinder (10). The bottom of the piston rod (11) has a mounting hole (14), and the top of the piston rod (11) is sealed and fixed to the heater metal shell (18). The piston rod (11) and the heater metal shell (18) are connected. 18) The contact surface is opened (17), and the anode (19) with through holes is fixed on the top of the heater metal shell (18). The sensor shell (16) passes through the piston rod (11), the heater metal shell (18) and the anode (19) and is fixed to the three respectively. The sensor (15) is installed inside the sensor shell (16). The insulating shell (20) is placed above the heater metal shell (18) and the two are in sealed contact. The insulating shell (20) forms a conical cavity, and the top of the cavity is open. The sensor (15) is perpendicular to the opening plane of the insulating shell (20) and coaxial with the conical insulating shell (20). The first wire (5) connects the workpiece (1) to the power supply (4), the second wire (6) connects the anode (19) to the power supply (4), and the shield wire (9) connects the sensor (15) to the analog system (8). The workpiece (1) is located on one side of the insulating shell (20); The ratio of the conductive cross-sectional area of ​​the anode (19) to the area of ​​the plasma discharge region on the workpiece surface is 5 to 10. The automatic control system (7) provides control signals to the power supply (4) based on temperature data. When adjusting the preset voltage, the high voltage setting range is 280~340V, the medium voltage setting range is 180~240V, and the low voltage setting range is 20~40V. The sensor (15) measures the surface temperature of the workpiece (1). During high-voltage heat treatment, when the surface temperature is 100~200℃ higher than the Ac3 temperature of the workpiece material, the automatic control system (7) controls the power supply (4) to reduce the voltage to medium voltage. When the surface temperature is 100-200℃ lower than the Ac3 temperature of the workpiece material, the automatic control system (7) controls the power supply (4) to increase the voltage to high voltage. The voltage is increased and decreased in cycles until the depth of the hardened layer (2) on the surface of the workpiece (1) reaches the predetermined requirement. Then the automatic control system (7) controls the power supply (4) to reduce the voltage to low voltage.

2. The electrolytic plasma heat treatment equipment according to claim 1, characterized in that, Electrolyte is supplied to cylinder (10) through pipe (13), piston rod (11) moves out of cylinder (10) and raises heater until the gap (3) between workpiece (1) surface and heater insulating shell (20) reaches the predetermined size. Electrolyte enters the groove of heater metal shell (18) through hole (17), and then enters the conical cavity formed by insulating shell (20) in the form of jet through the through hole of anode (19). The power supply (4) applies voltage to the anode (19) and the workpiece (1) through the first wire (5) and the second wire (6). The electrolyte jet is energized between the anode (19) and the workpiece (1), forming a thin vapor layer and local high pressure at the boundary between the workpiece (1) and the electrolyte jet, which excites plasma discharge and forms a hardened layer (2). The sensor (15) measures the temperature of the heated surface of the workpiece (1) in a non-contact manner and provides the temperature to the simulation system (8) through the shielding wire (9). After being converted by the simulation system (8), the temperature is provided to the automatic control system (7). The automatic control system (7) provides a control signal to the power supply (4) based on the temperature data and adjusts the preset voltage.

3. The electrolytic plasma heat treatment equipment according to claim 1, characterized in that: The heater's metal casing (18) is made of stainless steel, and its insulating casing (20) is made of fluoroplastic.

4. The electrolytic plasma heat treatment equipment according to claim 1, characterized in that: The sensor (15) used to measure the temperature of the heated surface of the workpiece (1) is made of a photoresistor.

5. The electrolytic plasma heat treatment equipment according to claim 2, characterized in that: The sensor (15) is embedded 10-20 mm below the electrolyte.

6. The electrolytic plasma heat treatment equipment according to claim 2, characterized in that: The mounting hole (14) is used to control the flow rate of the electrolyte.

7. The electrolytic plasma heat treatment equipment according to claim 2, characterized in that: The orifice (17) is used to control the flow rate of the electrolyte.

Images