Cryogenic-large electric pulse composite auxiliary cutting device and method

Abstract

The invention discloses a device and method for generating a fine-grain part through copious cooling-large electric pulse composite auxiliary cutting. The device comprises a machine tool chuck, a machine tool tailstock, a tip, a liquid nitrogen heat insulation cylinder, a cutter, an electric brush, a pulse power source and an oscilloscope. A workpiece is clamped through a machine tool chuck, a machine tool tailstock and a tip; the liquid nitrogen heat insulation cylinder sleeves the periphery of the workpiece for cooling and subzero treatment, and the pulsed power supply is applied to the workpiece through the electric brush, the pulsed power supply and the oscilloscope; according to the method, a workpiece is firstly cooled, pulse current is applied to the cooled workpiece, cutting machining is carried out, and subzero treatment is carried out after machining is completed; according to the method, on one hand, the rapid temperature change of subzero treatment and large electric pulse and the non-thermal effect of the large electric pulse are used for inhibiting the growth of recrystallized grains of a workpiece, and the microstructure and the mechanical property of a machined part are regulated, controlled and optimized; on the other hand, flow stress of materials is reduced through large electric pulses, cutting force is reduced, and tool abrasion is reduced; in addition, high-temperature oxidation of the workpiece can be avoided by cutting in a low-temperature environment.

Description

Technical Field

[0001] The present invention belongs to the field of cutting machining, and particularly relates to a device and method for cryogenic-high electric pulse composite assisted cutting. Background Art

[0002] In the existing cutting machining process, difficult-to-machine metal materials have high hardness and work hardening, resulting in serious tool wear, low machining efficiency, and high costs. Electric pulse assisted cutting utilizes the Joule heat effect and non-thermal effect of pulsed current, which can significantly reduce the flow stress of the workpiece material, reduce the cutting resistance, thereby improving the machining efficiency and reducing tool wear. However, due to the thermal effect existing in cutting machining and pulsed current, especially in the case of large pulsed current, on the one hand, the material will recrystallize to generate coarse grains, reducing the mechanical properties of the part. As shown by the Hall-Petch formula, the larger the grain size, the lower the material strength; on the other hand, the existence of the thermal effect will also cause thermal stress and serious deformation of the part, reducing the machining quality; in addition, the thermal effect will generate an oxide layer on the material surface, and the subsequent pickling process to remove it will cause serious environmental pollution, and the tip discharge phenomenon of the current will cause excessive softening of the chip, resulting in the phenomenon of chip sticking to the tool, affecting normal chip removal.

[0003] For coarse-grained parts, the existing processing mainly uses subsequent heat treatment processes to regulate and optimize the mechanical properties. The basic mechanism of heat treatment is that heat energy activation promotes diffusion, but the diffusion requires a long time and the production efficiency is low. And along with the progress of heat treatment, the surface of the sheet still needs pickling treatment to remove the generated oxide layer. Cryogenic treatment can change the microstructure such as the grain structure inside the material faster, improve the mechanical properties, and the overall device is simpler and more economical than heat treatment.

[0004] Therefore, when performing electro-pulse assisted cutting in a cryogenic environment, on the one hand, the pulsed current can be used to assist in improving the efficiency and quality of cutting; on the other hand, the large temperature change between the cryogenic environment and the electro-pulse-cutting thermal effect, as well as non-thermal effects such as the electron wind force of the instantaneous large electro-pulse passing through the material, can induce atomic diffusion, dislocation migration, lattice expansion, etc., which promote the recrystallization of metals, hinder the growth of recrystallized grains, significantly refine the grains, and produce fine-grained parts with excellent machining and mechanical properties. In the prior art, such as the published patent with the publication number CN 116728104 A and the name "An Electro-Pulse-Liquid Nitrogen Cooling Composite Assisted Cutting Method and Device", in this device, the workpiece needs to be set on the machine tool and the workpiece is located between two brushes before processing. When officially processing, a pulsed current is first applied to the workpiece through the two brushes, and then cutting starts. During the processing, the temperature is monitored in real time through a temperature sensor. When the temperature reaches the set value, liquid nitrogen is used to cool the front and rear tool faces of the tool to achieve electro-pulse and liquid nitrogen cooling composite assisted cutting. However, in this solution, only cooling is carried out during the cutting process, and the overall temperature cannot reach the temperature required for cryogenic treatment. Coarse grains will still be generated after processing, thus reducing the mechanical properties of the parts. Summary of the Invention

[0005] To solve the problems existing in the prior art, the present invention provides a device and method for cryogenic-large electro-pulse composite assisted cutting, which effectively controls the temperature rise generated by the pulsed current and cutting in the electro-pulse assisted cutting process by using a cryogenic environment. It can not only utilize the rapid temperature change of the cryogenic and electro-pulse thermal effects and the non-thermal effect of the large electro-pulse to accelerate the internal recrystallization refinement of the material and inhibit grain refinement, produce fine-grained parts with excellent machining and mechanical properties, but also improve the cutting efficiency and inhibit the generation of oxide layers.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a cryogenic - large electric pulse composite assisted cutting device, which includes a machine tool chuck, a machine tool tailstock, a center, a liquid nitrogen heat insulation cylinder, a cutting tool, a carbon brush, a pulse power supply and an oscilloscope; the machine tool chuck is connected to a machine tool power source and clamps a workpiece, the machine tool tailstock is slidably connected to a machine tool slide rail, the center is inserted into the machine tool tailstock and abuts against the workpiece; the liquid nitrogen heat insulation cylinder is sleeved outside the workpiece, a storage layer is arranged inside the liquid nitrogen heat insulation cylinder, the storage layer is communicated with an external liquid nitrogen source, and a working window is also opened on the liquid nitrogen heat insulation cylinder; the carbon brush and the cutting tool are arranged on the top of a machine tool cross slide, and during machining, the carbon brush and the cutting tool pass through the working window and contact the workpiece; there are two groups of carbon brushes and they are arranged on both sides of the cutting tool, the positive and negative electrodes of the pulse power supply are electrically connected to a group of carbon brushes respectively, and the oscilloscope is arranged in the circuit between the carbon brush and the pulse power supply; a temperature sensor is also arranged in the storage layer, and the temperature sensor is electrically connected to a computer.

[0008] Preferably, the carbon brush includes a carbon brush holder, a regulator and a brush head; the carbon brush holder is arranged on the machine tool cross slide, the brush head is connected to the carbon brush holder through the regulator, the regulator is used to push the brush head to contact the workpiece, and the brush head is connected to an external pulse power supply.

[0009] Preferably, the regulator includes a sleeve and a spring, the sleeve is connected to the carbon brush holder, the spring is arranged inside the sleeve, one end of the spring is connected to the carbon brush holder, and the other end is connected to the carbon brush.

[0010] Preferably, it further includes a liquid nitrogen dewar, a liquid nitrogen dewar switch, a booster valve controller, a flow control valve, a liquid nitrogen conduit, a liquid nitrogen heat insulation cylinder, and an outlet flow control valve; the liquid nitrogen dewar switch is arranged on the liquid nitrogen dewar, and both the inlet pipeline and the return pipeline between the liquid nitrogen dewar switch and the liquid nitrogen heat insulation cylinder are communicated through the liquid nitrogen conduit; the booster valve controller and the flow control valve are arranged on the inlet pipeline, and the outlet flow control valve is arranged on the return pipeline; both the flow control valve and the booster control valve are electrically connected to the computer.

[0011] Preferably, it further includes a heat insulation and insulation chuck sleeve, a chuck heat insulation block, a heat insulation and insulation tailstock sleeve, a tailstock heat insulation block and an insulating tool holder; the chuck heat insulation block is arranged inside the chuck sleeve, and the chuck clamps the workpiece through the chuck sleeve; the tailstock heat insulation block and the center are sequentially inserted into the heat insulation and insulation tailstock sleeve, and the heat insulation and insulation tailstock sleeve is inserted into the machine tool tailstock; the insulating tool holder is arranged on the cross slide and is used to clamp the cutting tool.

[0012] Preferably, the pulse power supply outputs a pulse current with a frequency of 20Hz - 20000Hz, a pulse width of 10μs - 2000μs, and a peak current of 100A - 10000A.

[0013] Preferably, the lower end surface of the working window slopes downward.

[0014] A cryogenic - large electric pulse composite assisted cutting method, which uses the above - mentioned cryogenic - large electric pulse composite assisted cutting device for cutting, specifically includes the following steps:

[0015] S1: First, clamp the workpiece with a machine tool chuck, then sleeved the liquid nitrogen heat insulation cylinder around the workpiece, seal the working window on the liquid nitrogen heat insulation cylinder, and finally move the machine tool tailstock to drive the center tip to abut against the workpiece;

[0016] S2: Start the external nitrogen source to inject liquid nitrogen into the storage layer of the liquid nitrogen heat insulation cylinder to cool the workpiece;

[0017] S3: Remove the seal, start the pulse power supply, move the cross slide to make the brush first contact the surface of the workpiece to apply a pulse current to the workpiece. After the oscilloscope has data, start the machine tool and move the tool to start cutting;

[0018] S4: After the workpiece is processed, move the cross slide to retract the tool. The tool tip first leaves the surface of the workpiece, and the left and right brushes then leave the surface of the workpiece. The oscilloscope reading disappears. Shut down the machine tool and cut off the pulse power supply;

[0019] S5: Perform cryogenic treatment on the workpiece with liquid nitrogen;

[0020] S6: Extract the liquid nitrogen in the liquid nitrogen heat insulation cylinder to heat up the workpiece.

[0021] Preferably, the treatment temperature in S2 and S5 is less than or equal to - 186°C, and the temperature holding time is at least 5 min.

[0022] Preferably, liquid nitrogen in S2 can be replaced by liquid nitrogen dioxide.

[0023] Preferably, the heating treatment in S6 is a slow heating treatment at 1°C / s until room temperature.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The cryogenic environment generated by liquid nitrogen, the heat effect of cutting and large electric pulse lead to rapid temperature changes. On the one hand, it reduces the heat effect of cutting and large electric pulse, reduces the temperature rise generated during the large electric pulse assisted cutting process, and inhibits the occurrence of recrystallized grain growth; on the other hand, a larger temperature difference improves the rate of recrystallized grain refinement and generates finer recrystallized grains, improving the mechanical and mechanical properties of parts to a greater extent.

[0026] 2. The instant large electric pulse, through non-thermal effects such as the electron wind force in the metal material, promotes the recrystallization behavior of the metal through atomic diffusion, dislocation migration, and lattice expansion in the material, further hinders the growth of recrystallized grains, significantly refines the grains, and regulates and optimizes the microstructure and mechanical properties of the metal material;

[0027] 3. Through the ultra-strong low temperature of liquid nitrogen, the thermal effects of cutting and large electric pulses are inhibited in the cryogenic environment, avoiding the oxidation and denaturation behavior of the material at high temperatures, and suppressing the thermal stress and severe deformation of the parts caused by the existence of thermal effects.

[0028] 4. Based on the principle of the shortest circuit and the smallest resistance and the skin effect of pulsed current, most of the pulsed current applied by the left and right brush devices that move synchronously with the cutting tool will flow through the cutting area on the surface of the workpiece between the two brush devices. Compared with the overall energization of the workpiece, the Joule heat effect of the current is reduced, bringing higher cutting efficiency and lower cost consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of the device of the present invention;

[0030] Figure 2 is a schematic structural diagram of the liquid nitrogen heat insulation cylinder in the present invention;

[0031] Figure 3 is a sectional view of the liquid nitrogen heat insulation cylinder in the present invention;

[0032] Figure 4 is a schematic structural diagram of the brush in the present invention;

[0033] Figure 5 is a sequence diagram of the method of the present invention.

[0034] The description of the reference numerals in the drawings is as follows:

[0035] 11. Machine tool chuck; 12. Heat insulation and insulation chuck sleeve; 13. Chuck heat insulation block;

[0036] 21. Machine tool tailstock; 22. Center; 23. Heat insulation and insulation tailstock sleeve; 24. Tailstock heat insulation block;

[0037] 3. Liquid nitrogen heat insulation cylinder; 31. Storage layer; 32. Working window;

[0038] 41. Cutting tool; 42. Insulating tool holder;

[0039] 51. Brush; 511. Brush head; 512. Regulator; 5121. Spring; 5122. Sleeve; 513. Brush holder;

[0040] 6. Pulse power supply; 7. Oscilloscope;

[0041] 81. Liquid nitrogen Dewar tank; 82. Liquid nitrogen Dewar tank switch; 83. Booster valve controller; 84. Flow control valve; 85. Liquid nitrogen conduit; 86. Outlet flow control valve; 87. Temperature sensor;

[0042] 9. Computer. Detailed implementation manners

[0043] The accompanying drawings are only for illustrative purposes and should not be construed as limiting the present patent; for better illustrating this embodiment, some components in the accompanying drawings may be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted. The positional relationships described in the accompanying drawings are only for illustrative purposes and should not be construed as limiting the present patent.

[0044] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "long", "short", etc. indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting the present patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0045] The technical solutions of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0046] Embodiment 1

[0047] As Figures 1-3As shown in the figure, a device for cryogenic and high-voltage electric pulse composite assisted cutting includes a machine tool chuck 11, a machine tool tailstock 21, a center 22, a liquid nitrogen heat insulation cylinder 3, a cutting tool, a brush 51, a pulse power supply 6 and an oscilloscope 7. The machine tool chuck 11 is connected to a machine tool power source and clamps a workpiece. The machine tool tailstock 21 is slidably connected to a machine tool slide rail. The center 22 is inserted into the machine tool tailstock 21 and abuts against the workpiece. The liquid nitrogen heat insulation cylinder 3 is sleeved around the periphery of the workpiece. A storage layer 31 is arranged inside the liquid nitrogen heat insulation cylinder 3. The storage layer 31 is communicated with an external liquid nitrogen source. A working window 32 is also opened on the liquid nitrogen heat insulation cylinder 3. The brush 51 and the cutting tool are arranged on the top of a machine tool cross slide. During machining, the brush 51 and the cutting tool pass through the working window 32 and contact the workpiece. There are two groups of brushes 51 and they are arranged on both sides of the cutting tool. The positive and negative electrodes of the pulse power supply 6 are electrically connected to a group of brushes 51 respectively. The oscilloscope 7 is arranged in the circuit between the brush 51 and the pulse power supply 6. A temperature sensor 87 is also arranged inside the storage layer 31. The temperature sensor 87 is electrically connected to a computer 9.

[0048] Working principle of this embodiment: Before machining the workpiece, first clamp the workpiece with the machine tool chuck 11, then sleeve the liquid nitrogen heat insulation cylinder 3 around the periphery of the workpiece, and then push the machine tool tailstock 21 to drive the center 22 through the machine tool tailstock 21 to abut against one end of the workpiece away from the machine tool chuck 11, thus completing the installation of the workpiece. Before the workpiece is formally machined, it is necessary to first seal the working window 32 on the liquid nitrogen heat insulation cylinder 3 and inject liquid nitrogen into the storage layer 31 of the liquid nitrogen heat insulation cylinder 3. The temperature inside the storage layer is monitored by the temperature sensor 87. After injecting the liquid nitrogen, the temperature inside the liquid nitrogen heat insulation cylinder 3 will also decrease, and the workpiece is also cooled. After cooling, the temperature of the workpiece is the same as or close to that inside the storage layer of the liquid nitrogen. Then remove the seal of the working port, start the pulse power supply 6, move the cross slide to feed the tool, so that the brush 51 first makes close contact with the surface of the workpiece. At this time, a pulsed current is introduced into the surface cutting area. When the oscilloscope 7 has data, start the lathe, and the workpiece rotates with the machine tool chuck 11. The brush 51 moves synchronously with the tool feed driven by the cross slide. The cutting tool tip contacts the surface of the workpiece and starts cutting. The chips generated by cutting will be discharged from the working window 32. Since the workpiece has been cooled before machining, it can offset the heat generated during cutting, avoiding excessive temperature during machining. After machining is completed, retract the tool and turn off the machine tool. Move the cross slide to retract the tool. The cutting tool tip first leaves the surface of the workpiece, and the left and right brushes 51 then leave the surface of the workpiece. The reading of the oscilloscope 7 disappears. Turn off the machine tool and cut off the pulse power supply 6. At this time, the workpiece is placed in the liquid nitrogen heat insulation cylinder for a period of time for cryogenic treatment. Finally, extract the liquid nitrogen in the liquid nitrogen heat insulation cylinder 3 back to the liquid nitrogen dewar 81. As the liquid nitrogen is extracted, the temperature inside the liquid nitrogen heat insulation cylinder 3 also rises. When it returns to room temperature, take out the fine-grained part processed from the machine tool chuck 11.

[0049] Beneficial effects of this embodiment: The cryogenic environment generated by liquid nitrogen, the heat effects of cutting and large electric pulses lead to extremely rapid temperature changes. On the one hand, it suppresses the heat effects of cutting and large electric pulses, reduces the temperature rise generated during the process of large electric pulse-assisted cutting, and inhibits the occurrence of recrystallized grain growth. On the other hand, the larger temperature difference increases the rate of recrystallized grain refinement and generates finer recrystallized grains, improving the mechanical and mechanical properties of the parts to a greater extent.

[0050] Embodiment 2

[0051] As Figure 1 、 4 shown, another embodiment of a cryogenic-large electric pulse composite-assisted cutting device. On the basis of Embodiment 1, the main difference from Embodiment 1 is that the brush 51 includes a brush holder 513, a regulator 512 and a brush head 511; the brush holder 513 is arranged on the cross slide of the machine tool, the brush head 511 is connected to the brush holder 513 through the regulator 512, the regulator 512 is used to push the brush head 511 into contact with the workpiece, and the brush head 511 is connected to the external pulse power supply 6; two groups of brushes 51 are provided and are respectively arranged on both sides of the cutting tool 41.

[0052] The regulator includes a sleeve 5122 and a spring 5121. The sleeve 5122 is connected to the brush 51 holder, the spring 5121 is arranged inside the sleeve 5122, one end of the spring 5121 is connected to the brush 51 holder, and the other end is connected to the brush 51.

[0053] Working principle of this embodiment: In the initial state, the spring 5121 is in a free state, and the distance between the brush head 511 and the workpiece supported by the spring 5121 is closer than the distance between the cutting edge of the cutting tool 41 and the workpiece; when feeding, the brush 51 contacts the workpiece first, at this time the spring 5121 will be compressed, and the brush head 511 will fit on the workpiece surface under the elastic force of the spring 5121 and will not separate; after the brush 51 contacts the workpiece and the oscilloscope 7 reacts, continue to feed to make the cutting tool 41 perform cutting; when the machining is completed, the cutting edge of the cutting tool 41 leaves the workpiece first and then the brush head 511 leaves the workpiece. When the brush head 511 leaves the workpiece, the oscilloscope 7 will disconnect the display, and at this time the pulse power supply 6 can be turned off.

[0054] Advantages of this embodiment: The brush 51 will always maintain contact with the workpiece under the elastic force of the spring 5121, and the spring 5121 has elastic force. When the cutting tool cuts in the left-right direction, the brush 51 will tilt in the direction opposite to the cutting direction. Therefore, it will not be a rigid part scratching on the workpiece surface and causing damage to the workpiece surface. In addition, based on the principle of the shortest circuit and the minimum resistance and the skin effect of pulsed current, most of the pulsed current applied to the left and right brush devices that move synchronously with the cutting tool will flow through the cutting area on the workpiece surface between the two brush devices. Compared with the overall energization of the workpiece, the Joule heat effect of the current is reduced, bringing higher cutting efficiency and lower cost consumption.

[0055] The remaining technical features and working principles are the same as those in Embodiment 1.

[0056] Embodiment 3

[0057] As Figure 1 shown, another embodiment of a cryogenic - large electric pulse composite assisted cutting device, based on Embodiment 1, the main difference from Embodiment 1 is that the external liquid nitrogen source includes a liquid nitrogen dewar 81, a liquid nitrogen dewar switch 82, a booster valve controller 83, a flow control valve 84, a liquid nitrogen conduit 85, an outlet flow control valve 86 and a liquid nitrogen recovery tank 88; the liquid nitrogen dewar switch 82 is arranged on the liquid nitrogen dewar 81, and the inlet flow pipeline between the liquid nitrogen dewar switch 82 and the liquid nitrogen heat insulation cylinder 3 and the return pipeline between the liquid nitrogen recovery tank 88 and the liquid nitrogen heat insulation cylinder 87 are both connected through the liquid nitrogen conduit 85; the booster valve controller 83 and the flow control valve 84 are arranged on the inlet pipeline, both the flow control valve 84 and the booster control valve 83 are electrically connected to the computer 9, and the outlet flow control valve 86 is arranged on the return pipeline.

[0058] Working principle of this embodiment: The temperature inside the liquid nitrogen heat insulation cylinder 3 is monitored in real time through the temperature sensor 87. Before reaching the temperature threshold during cryogenic treatment, liquid nitrogen is continuously injected into the liquid nitrogen heat insulation cylinder 3; after reaching the temperature threshold, the liquid nitrogen dewar switch 82 and the booster valve controller 83 are closed to keep the temperature inside the liquid nitrogen heat insulation cylinder 3 at the temperature threshold; after reaching the temperature threshold and maintaining for a period of time to perform cryogenic treatment on the workpiece, when starting to process, the outlet flow control valve 86 is opened. By continuously injecting liquid nitrogen, the heat generated during processing can be taken away, and the liquid nitrogen after absorbing heat flows back into the liquid nitrogen recovery tank 88 to ensure that the entire workpiece is in a low-temperature state; when the processing is completed, the liquid nitrogen dewar switch 82 is closed to stop injecting new liquid nitrogen, and the outlet flow control valve is kept open. As the liquid nitrogen inside the liquid nitrogen heat insulation cylinder 3 decreases, the temperature of the workpiece finally rises.

[0059] Advantages of this embodiment: The pressure boosting valve controller 83 and the flow control valve 84 can control the flow rate of liquid nitrogen entering the liquid nitrogen isolation barrel, thereby realizing the control of the cryogenic treatment temperature. In addition, by setting the temperature sensor 87, the temperature inside the liquid nitrogen heat insulation barrel can be detected to avoid affecting the cryogenic treatment effect due to insufficient temperature. In addition, by establishing an inflow route between the liquid nitrogen heat insulation cylinder 3 and the liquid nitrogen Dewar tank 81 and a reflux route between the liquid nitrogen heat insulation cylinder 3 and the liquid nitrogen recovery tank 88, the circulation of liquid nitrogen inside the liquid nitrogen heat insulation cylinder can be realized, and finally, it is ensured that the temperature inside the liquid nitrogen heat insulation cylinder is in a relatively low state, and thus the workpiece is also in a low-temperature state.

[0060] The remaining technical features and working principles are the same as those in Embodiment 1.

[0061] Embodiment 4

[0062] As Figures 1-2 shown, another embodiment of a cryogenic - large electric pulse composite assisted cutting device, on the basis of Embodiment 1, the main difference from Embodiment 1 is that it further includes a heat insulation and insulation chuck sleeve 12, a chuck heat insulation block 13, a heat insulation and insulation tailstock sleeve 23, a tailstock heat insulation block 24, and an insulating tool rest 42; the chuck heat insulation block 13 is arranged inside the heat insulation and insulation chuck sleeve 12, the chuck first clamps the heat insulation and insulation chuck sleeve 12 and then clamps the workpiece through the heat insulation and insulation chuck sleeve 12; the tailstock heat insulation block 24 and the center 22 are sequentially inserted into the heat insulation and insulation tailstock sleeve 23, and the heat insulation and insulation tailstock sleeve 23 is inserted into the machine tool tailstock 21; the insulating tool rest 42 is arranged on the cross slide and is used for clamping the cutting tool 41.

[0063] Working principle of this embodiment: Press the workpiece against the chuck heat insulation block 13 and insert it into the machine tool chuck 11 with the heat insulation and insulation chuck sleeve 12. Press the rear end of the center 22 against the tailstock heat insulation block 24 and insert it into the machine tool tailstock 21 with the heat insulation and insulation tailstock sleeve 23; insert the workpiece into the workpiece hole of the liquid nitrogen heat insulation cylinder 3, move the center 22 and insert it into the center 22 hole of the liquid nitrogen heat insulation cylinder 3 and press against the workpiece to ensure good sealed contact between the heat insulation and insulation chuck sleeve 12, the liquid nitrogen heat insulation cylinder 3, and the heat insulation and insulation tailstock sleeve 23; the cutting tool is clamped in the insulating tool rest 42.

[0064] Advantages of this embodiment: By setting the heat insulation and insulation chuck sleeve 12, the heat insulation and insulation tailstock sleeve 23, and the insulating tool rest 42, it can be avoided that the workpiece transfers electricity to the machine tool when electrified, thus causing harm to the machine tool operator.

[0065] The remaining technical features and working principles are the same as those in Embodiment 1.

[0066] Embodiment 5

[0067] As Figures 1-2As shown in the figure, another embodiment of a cryogenic - large electric pulse composite assisted cutting device. Based on Embodiment 1, the main difference from Embodiment 1 is that the pulse power supply 6 outputs a pulse current with a frequency of 20Hz - 20000Hz, a pulse width of 10μs - 2000μs, and a peak current of 100A - 10000A.

[0068] Another example Figure 3 As shown in the figure, the lower end surface of the working window 32 slopes downward.

[0069] The working principle of this embodiment: By setting a specific pulse power supply 6, the power output by the pulse power supply 6 is within this range, avoiding the situation that the output power fails to meet the processing requirements or exceeds the requirements, thus affecting the processing; during cutting, chips will be generated, and the chips generated during processing will be discharged from the working window 32. Since the lower end surface of the working window 32 slopes downward, it can finally play a role in guiding the chips.

[0070] The remaining technical features and working principles are the same as those in Embodiment 1.

[0071] Embodiment 6

[0072] As Figure 5 As shown in the figure, a cryogenic - large electric pulse composite assisted cutting method uses any one of the cryogenic - large electric pulse composite assisted cutting devices in Embodiments 1 - 5 for cutting, and specifically includes the following steps:

[0073] S1: First, clamp the workpiece with the machine tool chuck 11, then sleeved the liquid nitrogen heat insulation cylinder 3 around the workpiece, and finally move the machine tool tailstock 21 to drive the center tip 22 to abut against the workpiece; and seal the working window 32 on the liquid nitrogen heat insulation cylinder 3.

[0074] S2: Start the external nitrogen source to inject liquid nitrogen into the storage layer 31 of the liquid nitrogen heat insulation cylinder 3.

[0075] S3: Remove the seal and start the pulse power supply 6. Move the cross slide so that the brush 51 first contacts the surface of the workpiece to apply a pulse current to the workpiece. After the oscilloscope 7 has data, start the machine tool and move the tool to start cutting.

[0076] S4: After the workpiece is processed, move the cross slide to retract the tool. The tool tip first leaves the surface of the workpiece, and the left brush 51 and the right brush 51 then leave the surface of the workpiece. The reading of the oscilloscope 7 disappears. Turn off the machine tool and cut off the pulse power supply 6.

[0077] S5: The liquid nitrogen performs cryogenic treatment on the workpiece.

[0078] S6: Withdraw the liquid nitrogen in the liquid nitrogen heat insulation cylinder 3 to perform a warming treatment on the workpiece.

[0079] Advantages of this embodiment: The ultra-low temperature environment created by liquid nitrogen, the heat generated during cutting and large current pulses cause the temperature to change rapidly. This not only suppresses the heat generated during cutting and large current pulses, reducing the temperature rise during large current pulse-assisted cutting, but also prevents the grains from growing larger during recrystallization. At the same time, the larger temperature difference also accelerates the speed of grain refinement during recrystallization, producing finer grains, which can significantly improve the mechanical and mechanical properties of the parts.

[0080] Embodiment 7

[0081] A cryogenic-high electric pulse composite assisted cutting method. Based on Embodiment 6, the main difference from Embodiment 6 is that in S2 and S5, the processing temperature is less than or equal to -186°C, and the temperature holding time is at least 5 minutes.

[0082] Advantages of this embodiment: By subjecting the workpiece to cryogenic treatment in a specific temperature environment and maintaining it for a period of time, the workpiece is in a very low temperature state, avoiding the overall temperature of the workpiece not meeting the processing requirements.

[0083] Embodiment 8

[0084] A cryogenic-high electric pulse composite assisted cutting method. Based on Embodiment 6, the main difference from Embodiment 6 is that in S5, the heating process is a slow heating process at 1°C / s until room temperature.

[0085] Advantages of this embodiment: By controlling the heating rate, it is avoided that the metal material workpiece heats up too fast and thus recrystallizes to form coarse grain particles.

[0086] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A device for deep cooling and large electric pulse composite assisted cutting, characterized in that: The invention comprises a machine tool chuck (11), a machine tool tailstock (21), a center (22), a liquid nitrogen heat-insulating cylinder (3), a tool (41), a brush (51), a pulse power supply (6) and an oscilloscope (7); the machine tool chuck (11) is connected to a machine tool power source and clamps a workpiece; the machine tool tailstock (21) is slidably connected to a machine tool slide rail; the center (22) is plugged into the machine tool tailstock (21) and abuts against the workpiece; the liquid nitrogen heat-insulating cylinder (3) is sleeved on the periphery of the workpiece; a storage layer (31) is arranged inside the liquid nitrogen heat-insulating cylinder (3); the storage layer (31) is connected to an external liquid nitrogen source; and the liquid nitrogen heat-insulating cylinder (3) is provided with a storage layer (31). The storage layer (31) is connected to an external liquid nitrogen source. A working window (32) is also provided; the brushes (51) and the tool (41) are arranged on the top of the small slide of the machine tool, and during processing, the brushes (51) and the tool (41) pass through the working window (32) and contact the workpiece; there are two groups of brushes (51) and they are arranged on both sides of the tool (41); the positive and negative electrodes of the pulse power supply (6) are electrically connected to a group of brushes (51) respectively, and the oscilloscope (7) is arranged in the circuit of the brushes (51) and the pulse power supply (6); a temperature sensor (87) is also arranged in the storage layer (31), and the temperature sensor (87) is electrically connected to the computer (9).

2. The device for deep cooling and large electric pulse composite assisted cutting according to claim 1 is characterized in that: The brush (51) comprises a brush holder (513), a regulator (512) and a brush head (511); the brush holder (513) is arranged on a small slide of a machine tool; the brush head (511) is connected to the brush holder (513) via the regulator (512); the regulator (512) is used to push the brush head (511) to contact a workpiece; and the brush head (511) is connected to an external pulse power supply (6).

3. The device for deep cooling and large electric pulse composite assisted cutting according to claim 2 is characterized in that: The regulator (512) comprises a sleeve (5122) and a spring (5121); the sleeve (5122) is connected to the brush holder (513); the spring (5121) is arranged inside the sleeve (5122); one end of the spring (5121) is connected to the brush holder (513), and the other end is connected to the brush head (511).

4. The device for deep cooling and large electric pulse composite assisted cutting according to claim 1 is characterized in that: The external liquid nitrogen source comprises a liquid nitrogen dewar tank (81), a liquid nitrogen dewar tank switch (82), a booster valve controller (83), a flow control valve (84), a liquid nitrogen conduit (85), an outlet flow control valve (86) and a liquid nitrogen recovery tank (88); the liquid nitrogen dewar tank switch (82) is arranged on the liquid nitrogen dewar tank (81), the inlet pipeline between the liquid nitrogen dewar tank switch (82) and the liquid nitrogen insulation cylinder (3) and the return pipeline between the liquid nitrogen recovery tank (88) and the liquid nitrogen insulation cylinder (87) are both connected through the liquid nitrogen conduit (85); the booster valve controller (83) and the flow control valve (84) are arranged on the inlet pipeline, the flow control valve (84) and the booster control valve (83) are both electrically connected to the computer (9), and the outlet flow control valve (86) is arranged on the return pipeline.

5. The device for deep cooling and large electric pulse composite assisted cutting according to claim 1 is characterized in that: The invention also comprises a heat-insulating chuck sleeve (12), a chuck heat-insulating block (13), a heat-insulating tailstock sleeve (23), a tailstock heat-insulating block (24) and an insulating tool holder (42); the chuck heat-insulating block (13) is arranged in the heat-insulating chuck sleeve (12); the chuck first clamps the heat-insulating chuck sleeve (12) and then clamps the workpiece through the heat-insulating chuck sleeve (12); the tailstock heat-insulating block (24) and the center (22) are sequentially inserted into the heat-insulating tailstock sleeve (23); the heat-insulating tailstock sleeve (23) is inserted into the tailstock (21) of the machine tool; the insulating tool holder (42) is arranged on a small slide and is used to clamp a tool (41).

6. The device for deep cooling and large electric pulse composite assisted cutting according to claim 1 is characterized in that: The pulse power supply (6) outputs a pulse current with a frequency of 20 Hz to 20000 Hz, a pulse width of 10 μs to 2000 μs, and a peak current of 100A to 10000A.

7. The device for deep cooling and large electric pulse composite assisted cutting according to claim 1 is characterized in that: The lower end surface of the working window (32) is inclined downward.

8. A method of deep cooling-large electric pulse composite assisted cutting, characterized in that: Cutting using a deep cooling-large electric pulse composite assisted cutting device as described in any one of claims 1 to 7 specifically comprises the following steps: S1: First, the workpiece is clamped by the machine tool chuck (11), then the liquid nitrogen heat insulation cylinder (3) is sleeved around the periphery of the workpiece, and the working window (32) on the liquid nitrogen heat insulation cylinder (3) is sealed, and finally the machine tool tailstock (21) is moved to drive the center (22) to abut against the workpiece; S2: starting an external nitrogen source to inject liquid nitrogen into the storage layer (31) of the liquid nitrogen insulation cylinder (3) to cool the workpiece; S3: Remove the seal, start the pulse power supply (6), move the small slide plate so that the brush (51) first contacts the workpiece surface to apply a pulse current to the workpiece, and after the oscilloscope (7) has data, start the machine tool and move the tool (41) to start cutting; S4: After the workpiece is processed, the small slide is moved to retract the tool, the tip of the tool (41) leaves the workpiece surface first, and the left brush (51) and the right brush (51) leave the workpiece surface later, the reading of the oscilloscope (7) disappears, the machine tool is turned off, and the pulse power supply (6) is cut off; S5: Liquid nitrogen performs deep cryogenic treatment on the workpiece; S6: Extract the liquid nitrogen in the liquid nitrogen insulation cylinder (3) to heat the workpiece.

9. The method of deep cooling-large electric pulse composite assisted cutting according to claim 8, characterized in that: The treatment temperature in S2 and S5 is less than or equal to -186°C, and the temperature is maintained for at least 5 minutes.

10. The method of deep cooling-large electric pulse composite assisted cutting according to claim 8, characterized in that: The temperature rise process in S6 is a slow temperature rise process of 1°C / s until reaching room temperature.

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