Device and method for machining internal threads through electromagnetic induction heat treatment assisted bending vibration

Abstract

The invention discloses a device and method for machining internal threads through electromagnetic induction heat treatment assisted bending vibration and belongs to the technical field of precise non-traditional machining. Electromagnetic induction heating is utilized, the hole wall surface of the workpiece is pretreated, the hole wall surface strength is regulated and controlled, and the thread tooth integrity and the surface quality are improved. Ultrasonic vibration is introduced in internal thread turning, the length and the thickness of a tool handle are set, so that the tool handle generates high-frequency bending vibration and drives an internal thread turning tool, and the tool handle is enabled to realize high-frequency micro-displacement swing of an XY plane by taking the tool handle as the center under the axial vibration action of a piezoelectric transducer and is coupled with macroscopic machining tracks of an X axis and a Y axis at the same time; the phenomena of chip blockage and friction aggravation under dry machining of the internal thread can be avoided, the phenomena that the thread surface is scratched due to untimely chip removal and burrs are generated are reduced, the surface quality of the internal thread tooth is further improved, and the machining precision is guaranteed; and the auxiliary heating rod is matched with the electromagnetic induction coil, so that heat on the surface of the hole wall can be quickly superposed, and the heating efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of precision special processing, and in particular relates to a device and method for electromagnetic induction heat treatment assisted bending vibration processing of internal threads of difficult-to-process materials such as metal-based and ceramic-based composite materials. Background Art

[0002] Metal-based and ceramic-based composite materials have excellent properties such as high strength, low density, and wear resistance. The fasteners (bolts, nuts, etc.) produced from them are widely used in the fields of aerospace, national defense, and military industry. However, in the production process of metal-based and ceramic-based composite bolts and nuts, especially the processing of nuts, the commonly used processing methods are tapping, milling, and turning. Due to the high hardness, brittleness, uneven distribution, and many hard points of metal-based and ceramic-based composite materials, when these three methods are used for precision processing, the thread teeth are easy to break, the tooth shape size accuracy is low, the thread surface has many defects and burrs, the tool wear is serious, and the processing cost is high, which makes it difficult to meet the high-efficiency and high-quality processing needs of high-end equipment fasteners. At present, some people have proposed improved internal thread processing technologies, such as designing special diamond flat-bottom tools (CN107052476A), designing new thread structures (CN113000952A), and designing low-density thread processing technology (CN 112759404A). However, there are still problems such as excessive stress concentration and microcracks during the processing leading to poor thread integrity, narrow material matching surface, uneven residual stress, low processing efficiency and high cost, which make it difficult to meet the mass production and reliability application of such structural parts.

[0003] Laser heating is used to pre-treat the processing area, adjust the material hardness, and then combine with ultrasonic vibration technology to improve the integrity of the thread teeth, the tooth shape size accuracy, and reduce tool wear. It is currently an effective means to improve processing efficiency. However, laser heating is not easy to control, the selection range is affected by the size of the spot, and there are problems such as temperature concentration and uneven distribution during the heating process. It is difficult to apply it to the internal thread processing of metal-based and ceramic-based composite materials.

[0004] Therefore, there is an urgent need for an efficient precision cutting device and method with low-damage internal thread processing characteristics to improve the accuracy and efficiency of precision internal thread processing and reduce the cost of internal thread processing to meet the high reliability and long service life performance of fasteners. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a device and method for electromagnetic induction heat treatment assisted bending vibration processing of internal threads to solve the technical problem that a high-efficiency, low-damage internal thread precision cutting device and method are urgently needed.

[0006] The device for electromagnetic induction heat treatment assisted bending vibration processing of internal threads comprises a lathe body and a high-frequency vibration turning device, wherein the lathe body comprises a machine tool, a high-speed spindle, a CNC X-axis, a CNC Y-axis and a turret; the CNC Y-axis is arranged on the CNC X-axis; the turret comprises a tool disc and a tool holder fixedly connected to the tool disc, and the turret is arranged on the CNC Y-axis; one end of the high-speed spindle is installed on the machine tool through a spindle clamp, and the other end of the high-speed spindle fixes the workpiece; the high-frequency vibration turning device comprises an ultrasonic generator, a finishing turning tool, an internal thread turning tool, a piezoelectric transducer and a tool handle; the ultrasonic generator is arranged on the machine tool; the internal thread turning tool is installed on the piezoelectric transducer through the tool handle; the piezoelectric transducer and the finishing turning tool are arranged on the tool disc through a clamp; the ultrasonic generator is electrically connected to the piezoelectric transducer;

[0007] The device for electromagnetic induction heat treatment-assisted bending vibration processing of internal threads also includes an electromagnetic induction heating device and a bus control system;

[0008] The electromagnetic induction heating device comprises an electromagnetic induction mainframe, a cylinder, a folding rod, an electromagnetic induction coil and an auxiliary heating rod, wherein the electromagnetic induction mainframe is fixedly mounted on a machine tool; the cylinder is fixedly mounted on a spindle fixture; a portion of the folding rod is a fixed portion, and another portion is a folding portion, the fixed portion and the folding portion are rotatably connected, the fixed portion is fixedly connected to the telescopic rod of the cylinder, and the electromagnetic induction coil is fixedly mounted on the folding portion; the electromagnetic induction coil is sleeved on the periphery of the workpiece, and the center of the electromagnetic induction coil coincides with the axis of the high-speed spindle, and the electromagnetic induction coil is connected to the electromagnetic induction mainframe; the auxiliary heating rod is mounted on the cutter head through a fixture, and the auxiliary heating rod is inserted into the inner hole of the workpiece in a preheating process before internal thread turning to contact-heat the hole wall of the workpiece;

[0009] The bus control system is provided with a processing program and a control system program, and the bus control system is respectively connected with the electromagnetic induction host, the ultrasonic generator, the cylinder and the lathe body through signal lines, and the processing program is determined by the optimal processing parameters of the electromagnetic induction heat treatment assisted bending vibration for internal thread turning obtained by simulation;

[0010] The relationship between the length l and thickness h of the shank is:

[0011]

[0012] Where A1 is the first mode coefficient; c is the material sound velocity; f j is the natural frequency, which is 20kHz.

[0013] The simulation includes:

[0014] 1) Establish an electromagnetic induction heating finite element model according to the material properties and dimensions of the workpiece to be processed. Simulate the heat affected zone of the workpiece by changing the output power, electromagnetic induction output frequency, electromagnetic induction output current, spindle speed, feed rate and cross-sectional area of ​​the auxiliary heating rod of the electromagnetic induction main machine. Extract the depth value of the corresponding temperature from the simulation results. This temperature is the effective softening temperature at which the material hardness of the workpiece is reduced. By consulting relevant literature or corresponding experiments, the effective depth of the workpiece material hardness reduction, i.e., the back cutting amount a, is established. p About the output power P of the electromagnetic induction host i 、Electromagnetic induction host output frequency f i 、Electromagnetic induction host output current I i , spindle speed n, feed rate v r and the multiple regression equation of the cross-sectional area S of the auxiliary heating rod;

[0015]

[0016] In the formula, α is the coefficient of the regression formula; a1, a2, a3, a4, a5, a6 are all parameter exponents;

[0017] 2) According to the material properties and dimensions of the workpiece, fine turning tool and internal thread turning tool, a finite element model of electromagnetic induction heating assisted cutting is established. By changing the amplitude A, spindle speed n, feed rate v r 、Back knife amount a p Simulate the cutting force during machining and establish the relationship between the cutting force and the amplitude A, spindle speed n, feed rate v r And back knife amount a p The multiple linear regression equation of

[0018]

[0019] In the formula, β, λ, ε, τ are all regression coefficients;

[0020] The optimal machining parameters for internal thread turning using electromagnetic induction heat treatment assisted bending vibration were obtained through simulation.

[0021] The processing parameters include electromagnetic induction output power, electromagnetic induction host output frequency, electromagnetic induction host output current, vibration frequency, amplitude, spindle speed, feed rate, back cutting amount and auxiliary heating rod model.

[0022] The method for machining internal threads by electromagnetic induction heat treatment assisted bending vibration comprises the following steps, which are performed in sequence:

[0023] Step 1: Use ANSYS Workbench and Maxwell finite element simulation software to perform electromagnetic induction heating bidirectional coupling simulation and cutting simulation, respectively, and establish the effective depth of the workpiece material hardness reduction, that is, the back cutting amount a p About the output power P of the electromagnetic induction host i , the output frequency f of the electromagnetic induction host i 、The output current I of the electromagnetic induction host i , high-speed spindle speed n, high-speed spindle feed rate v r and the multivariate regression equation of the cross-sectional area S of the auxiliary heating rod, and the cutting force on the output vibration frequency f of the ultrasonic generator j , the output amplitude A of the ultrasonic generator, the speed n of the high-speed spindle, the feed rate v of the high-speed spindle r And back knife amount a p The multivariate linear regression equation 2 is used to obtain the output power of the electromagnetic induction host, the output frequency of the electromagnetic induction host, the output current of the electromagnetic induction host, the output vibration frequency of the ultrasonic generator, the output amplitude of the ultrasonic generator, the speed of the high-speed spindle, the feed rate of the high-speed spindle, the setting of the back-cutting amount parameters and the optimal parameter value of the auxiliary heating rod model, which are input into the bus control system and the corresponding processing program is formulated;

[0024] The relationship between the length l and thickness h of the shank is set as:

[0025]

[0026] Where A1 is the first mode coefficient; c is the material sound velocity; f j is the natural frequency, which is 20kHz;

[0027] Step 2: Fix the workpiece to be processed on the high-speed spindle, fix the electromagnetic induction coil on the workpiece by adjusting the telescopic rod and folding rod of the cylinder, and adjust the distance between the electromagnetic induction coil and the workpiece;

[0028] Step 3: Turn on the bus control system to control the CNC X-axis, CNC Y-axis, turret and telescopic rod of the cylinder to return the machine tool to zero and calibrate the tool; turn on the electromagnetic induction host, set the output power, output frequency and output current, and the fixed heating area of ​​the electromagnetic induction coil on the workpiece is circular, and the center of the circle coincides with the spindle;

[0029] Step 4: Start the processing program in the bus control system and use the finishing turning tool to perform electromagnetic induction heating-assisted inner hole precision turning processing;

[0030] Step 5: After the inner hole fine turning is completed, the CNC X-axis is controlled to return to zero through the bus control system, and the cutter head is controlled to switch the fine turning tool to the auxiliary heating rod to preheat the hole wall;

[0031] Step 6: After the hole wall is heated and pretreated for the set time, the CNC X-axis is controlled to return to zero again through the bus control system, and the tool head is controlled to switch the auxiliary heating rod to the internal thread turning tool. At the same time, the ultrasonic generator is turned on, and the output amplitude and frequency are set. Due to the setting of the length l and thickness h of the tool handle, high-frequency bending vibration can be generated, and the tool tip of the internal thread turning tool can be driven to achieve high-frequency micro-displacement swing in the XY plane with the tool handle as the center under the axial vibration of the piezoelectric transducer, while coupling the macro-machining trajectory of the X-axis and the Y-axis, and the workpiece is subjected to electromagnetic induction heat treatment assisted bending vibration internal thread turning processing;

[0032] At this point, a method for electromagnetic induction heat treatment assisted bending vibration processing of internal threads is completed.

[0033] The electromagnetic induction heating bidirectional coupling simulation is specifically as follows:

[0034] According to the material properties and size of the workpiece to be processed, the electromagnetic induction heating finite element model was established using ANSYS Workbench finite element simulation software. i , the output frequency f of the electromagnetic induction host i 、The output current I of the electromagnetic induction host i , high-speed spindle speed n, high-speed spindle feed rate v r And the cross-sectional area S of the auxiliary heating rod, the heat affected zone of the workpiece is simulated, and the depth value of the corresponding temperature is extracted from the simulation results. This temperature is the effective softening temperature at which the material hardness of the workpiece is reduced. By consulting relevant literature or corresponding experiments, the established multivariate regression equation is:

[0035]

[0036] In the formula, α is the coefficient of the regression formula; a1, a2, a3, a4, a5, and a6 are all parameter exponents.

[0037] The output current and the output frequency of the electromagnetic induction host in steps three, four and six and the setting of the hole wall heating pretreatment time in step five are all obtained through the simulation of the heat affected zone of the workpiece in step one.

[0038] The cutting simulation is specifically:

[0039] The electromagnetic induction heating assisted cutting finite element model is established according to the material properties and dimensions of the workpiece to be processed, the fine turning tool and the internal thread turning tool, and the output amplitude A of the ultrasonic generator, the speed n of the high-speed spindle, and the feed rate v of the high-speed spindle are changed. r 、Back knife amount a pThe cutting force during processing is simulated, and the established multivariate linear regression equation is:

[0040]

[0041] In the formula, β, λ, ε, τ are all regression coefficients, is the cutting force.

[0042] In step three, the electromagnetic induction host receives the instruction of the bus control system and generates current to heat the electromagnetic induction coil.

[0043] In step six, the ultrasonic generator receives the command of the bus control system and generates an electrical signal to enable the piezoelectric transducer to drive the internal thread turning tool to vibrate at a high frequency.

[0044] Through the above design scheme, the present invention can bring the following beneficial effects:

[0045] 1. The present invention utilizes electromagnetic induction heating to pre-treat the hole wall surface of the workpiece, adjust the surface strength of the hole wall, and then apply high-frequency vibration to the internal thread turning tool, thereby solving the problems of stress concentration, uneven residual stress, microcracks, and low processing efficiency during the turning process of internal threads of metal-based and ceramic-based composite materials, improving the integrity and surface quality of the thread teeth, and realizing efficient and low-damage preparation of internal threads of metal-based and ceramic-based composite materials.

[0046] 2. The present invention utilizes metal-based and ceramic-based composite materials for internal thread turning. By setting the length l and thickness h of the tool handle, it generates high-frequency bending vibration and drives the tool tip of the internal thread turning tool, so that it realizes high-frequency micro-displacement swing in the XY plane with the tool handle as the center under the axial vibration of the piezoelectric transducer, while coupling the macroscopic machining tracks of the X-axis and the Y-axis, which can avoid chip blockage and increased friction during dry machining of the internal thread, reduce the scratching of the thread surface and the generation of burrs caused by untimely chip removal, further improve the surface quality of the internal thread teeth, and ensure machining accuracy;

[0047] 3. The present invention uses an auxiliary heating rod in conjunction with an electromagnetic induction coil to rapidly add heat to the hole wall surface, thereby improving heating efficiency. The diameter of the auxiliary heating rod can be changed according to the processing of threads of various diameter series, which is suitable for large-scale and multi-variety processing needs;

[0048] 4. The CNC machine tool used in the present invention has a simple design structure, is easy to operate, and greatly reduces the cost of processing internal threads of metal-based and ceramic-based composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The present invention is further described below with reference to the accompanying drawings and specific embodiments:

[0050] Figure 1It is a schematic structural diagram of the device in the device and method for electromagnetic induction heat treatment assisted bending vibration processing of internal threads of the present invention;

[0051] Figure 2 It is a structural schematic diagram of the high-frequency vibration turning device in the device and method for electromagnetic induction heat treatment assisted bending vibration processing of internal threads of the present invention.

[0052] In the figure, 1-high-speed spindle, 2-cylinder, 3-ultrasonic generator, 4-folding rod, 5-tool disc, 6-tool holder, 7-CNC Y-axis, 8-CNC X-axis, 9-electromagnetic induction host, 10-electromagnetic induction coil, 11-workpiece, 12-spindle fixture, 13-finishing turning tool, 14-internal thread turning tool, 15-piezoelectric transducer, 16-tool handle, 17-auxiliary heating rod. DETAILED DESCRIPTION

[0053] like Figure 1 and Figure 2 As shown, an electromagnetic induction pretreatment bending vibration assisted internal thread processing device includes a lathe body, an electromagnetic induction heating device, a high-frequency vibration turning device and a bus control system.

[0054] The lathe body includes a machine tool, a high-speed spindle 1, a CNC X-axis 8, a CNC Y-axis 7, a turret and a workpiece 11. The turret includes a tool disc 5 and a tool holder 6. The tool disc 5 is fixedly connected to the tool holder 6. The CNC Y-axis 7 is arranged on the CNC X-axis 8. The tool holder 6 is arranged on the CNC Y-axis 7. The high-speed spindle 1 is installed on the machine tool through a spindle clamp 12. The workpiece 11 is arranged on the high-speed spindle 1.

[0055] The electromagnetic induction heating device includes an electromagnetic induction main unit 9, a cylinder 2, a folding rod 4, an electromagnetic induction coil 10 and an auxiliary heating rod 17. The electromagnetic induction main unit 9 is arranged on a machine tool, the electromagnetic induction coil 10 is fixed on the folding rod 4, and the folding rod 4 is arranged on the telescopic rod of the cylinder 2. To facilitate the disassembly and assembly of the workpiece and the heating of the workpiece, the electromagnetic induction coil 10 can be adjusted by the folding rod 4 connected to the telescopic rod of the cylinder 2. The cylinder 2 is arranged on a spindle clamp 12, and the auxiliary heating rod 17 is installed on the turret 5 through the clamp. The electromagnetic induction coil 10 is horizontally arranged on the periphery of the workpiece 11, and the center of the electromagnetic induction coil 10 coincides axially with the high-speed spindle 1, and the electromagnetic induction main unit 9 is connected to the electromagnetic induction coil 10.

[0056] The high-frequency vibration turning device includes an ultrasonic generator 3, a finishing turning tool 13, an internal thread turning tool 14, a piezoelectric transducer 15 and a tool handle 16. The ultrasonic generator 3 is arranged on a machine tool, the internal thread turning tool 14 is mounted on the piezoelectric transducer 15 through the tool handle 16, the piezoelectric transducer 15 and the finishing turning tool 13 are arranged on the tool disc 5 through a fixture, and the ultrasonic generator 3 is connected to the piezoelectric transducer 15.

[0057] The bus control system is provided with a processing program and a control system program, and is respectively connected with the electromagnetic induction host 9, the ultrasonic generator 3, the cylinder 2 and the lathe body through signal lines.

[0058] The method for machining internal threads by electromagnetic induction heat treatment assisted bending vibration comprises the following steps, which are performed in sequence:

[0059] Step 1: Use ANSYS Workbench and Maxwell finite element simulation software to perform electromagnetic induction heating bidirectional coupling simulation and cutting simulation. Provide guidance for the setting of electromagnetic induction output power, electromagnetic induction host output frequency, electromagnetic induction host output current, vibration frequency, amplitude, spindle speed, feed rate, back cutting amount parameters in the bus control system program and the selection of auxiliary heating rod model.

[0060] 1) Establish an electromagnetic induction heating finite element model according to the material properties and dimensions of the workpiece 11 to be processed, and simulate the heat affected zone of the workpiece 11 by changing the output power, output frequency, output current, speed, feed rate and cross-sectional area of ​​the auxiliary heating rod 17 of the electromagnetic induction host 9, and extract the depth value of the corresponding temperature from the simulation results. The temperature is the effective softening temperature at which the hardness of the material is reduced, which can be determined by referring to relevant literature or corresponding experiments, and the effective depth of the hardness reduction of the material, i.e., the back cutting amount a, is established. p The output power P of the electromagnetic induction host 9 i , the output frequency f of the electromagnetic induction host 9 i , the output current I of the electromagnetic induction host 9 i , the speed n of high-speed spindle 1, the feed rate v of high-speed spindle 1 r and a multiple regression equation 1 for the cross-sectional area S of the auxiliary heating rod 17;

[0061]

[0062] In the formula, α is the coefficient of the regression formula; a1, a2, a3, a4, a5, and a6 are all parameter exponents.

[0063] 2) According to the material properties and dimensions of the workpiece 11 to be processed and the tool, a finite element model of electromagnetic induction heating assisted cutting is established, and the output amplitude A of the ultrasonic generator 3, the speed n of the high-speed spindle 1, and the feed rate v of the high-speed spindle 1 are changed. r 、Back knife amount a p Simulate the cutting force during machining and establish the relationship between the cutting force and the amplitude A, spindle speed n, feed rate v r And back knife amount a p The multivariate linear regression equation 2 is:

[0064]

[0065] In the formula, β, λ, ε, τ are all regression coefficients;

[0066] The relationship between the length l and thickness h of the shank is set as:

[0067]

[0068] In the formula, A1 is the first mode coefficient, c is the material sound velocity, f j is the natural frequency, which is 20kHz.

[0069] 3) According to the multivariate regression equation on the effective depth of material hardness reduction and cutting force, the optimal machining parameters for electromagnetic induction pretreatment bending vibration-assisted internal thread turning are formulated, and the corresponding machining procedures are developed.

[0070] Step 2: The workpiece 11 to be processed is mounted and fixed on the high-speed spindle 1, and the electromagnetic induction coil 10 is fixed on the workpiece 11 by adjusting the telescopic rod and the folding rod 4 of the cylinder 2, and the distance between the electromagnetic induction coil 10 and the workpiece 11 is adjusted;

[0071] Step 3: Turn on the bus control system to control the CNC X-axis 8, CNC Y-axis 9, turret and telescopic rod of the cylinder 2, return the machine tool to zero and calibrate the tool; turn on the electromagnetic induction host 9, set the output current and the output frequency of the electromagnetic induction host 9, and the fixed heating area of ​​the electromagnetic induction coil 10 on the workpiece is circular, and the center of the circle coincides with the high-speed spindle 1;

[0072] Step 4: Open the processing program in the bus control system and perform electromagnetic induction heating assisted inner hole precision turning processing;

[0073] Step 5: After the inner hole fine turning process is completed, the CNC X-axis 8 is controlled to return to zero through the bus control system, and the cutter head is controlled to switch the fine turning tool 13 to the auxiliary heating rod 17 to preheat the hole wall;

[0074] Step 6: After the hole wall heating pretreatment is completed, the CNC X-axis 8 is controlled to return to zero again through the bus control system, and the tool head is controlled to switch the auxiliary heating rod 17 to the internal thread turning tool 14, and the ultrasonic generator 3 is turned on at the same time, and the output amplitude and frequency are set. Due to the setting of the length l and thickness h of the tool handle 16, high-frequency bending vibration can be generated, and the tool tip of the internal thread turning tool 14 can be driven to achieve high-frequency micro-displacement swing in the XY plane with the tool handle 16 as the center under the axial vibration of the piezoelectric transducer 15, while coupling the macroscopic processing trajectory of the X-axis and the Y-axis, and performing electromagnetic induction heat treatment assisted bending vibration internal thread turning processing on the workpiece 11;

[0075] At this point, the method of electromagnetic induction heat treatment assisted bending vibration processing of internal threads is completed.

[0076] In step 3, the electromagnetic induction host 9 receives the instruction of the bus control system and generates current to heat the induction coil.

[0077] The output current and the output frequency of the electromagnetic induction host 9 in steps 3, 4 and 6 and the setting of the hole wall heating pretreatment time in step 5 are all obtained through the temperature field simulation in step 1.

[0078] In step six, the ultrasonic generator 3 receives the instruction of the bus control system and generates an electrical signal to make the piezoelectric transducer 15 drive the internal thread turning tool 14 to vibrate at a high frequency.

Claims

1. A device for electromagnetic induction heat treatment-assisted bending vibration machining of internal threads, comprising a lathe body and a high-frequency vibration turning device, wherein the lathe body comprises a machine tool, a high-speed spindle (1), a numerically controlled X-axis (8), a numerically controlled Y-axis (7) and a turret; the numerically controlled Y-axis (7) is arranged on the numerically controlled X-axis (8); the turret comprises a tool disc (5) and a tool holder (6) fixedly connected to the tool disc (5), and the turret is arranged on the numerically controlled Y-axis (7); one end of the high-speed spindle (1) is mounted on the machine tool through a spindle fixture (12); The other end fixes the workpiece (11); the high-frequency vibration turning device comprises an ultrasonic generator (3), a finishing turning tool (13), an internal thread turning tool (14), a piezoelectric transducer (15) and a tool handle (16); the ultrasonic generator (3) is arranged on a machine tool; the internal thread turning tool (14) is mounted on the piezoelectric transducer (15) via the tool handle (16); the piezoelectric transducer (15) and the finishing turning tool (13) are arranged on a tool disc (5) via a fixture; the ultrasonic generator (3) is electrically connected to the piezoelectric transducer (15); Its characteristics are: It also includes an electromagnetic induction heating device and a bus control system; The electromagnetic induction heating device comprises an electromagnetic induction main machine (9), a cylinder (2), a folding rod (4), an electromagnetic induction coil (10) and an auxiliary heating rod (17), wherein the electromagnetic induction main machine (9) is fixedly mounted on a machine tool; the cylinder (2) is fixedly mounted on a spindle fixture (12); a portion of the folding rod (4) is a fixed portion, and another portion is a folding portion, the fixed portion and the folding portion are rotatably connected, the fixed portion is fixedly connected to the telescopic rod of the cylinder (2), and the electromagnetic induction coil (10) is fixedly mounted on the folding portion; the electromagnetic induction coil (10) is sleeved on the periphery of a workpiece (11), and the center of the electromagnetic induction coil (10) coincides with the axis of a high-speed spindle (1), and the electromagnetic induction coil (10) is connected to the electromagnetic induction main machine (9); the auxiliary heating rod (17) is mounted on a cutter head (5) through a fixture, and the auxiliary heating rod (17) is inserted into the inner hole of the workpiece (11) in a preheating process before internal thread turning to contact-heat the hole wall of the workpiece (11); The bus control system is provided with a processing program and a control system program. The bus control system is connected to the electromagnetic induction host (9), the ultrasonic generator (3), the cylinder (2) and the lathe body through signal lines. The processing program is determined by the optimal processing parameters of the electromagnetic induction heat treatment assisted bending vibration for internal thread turning obtained by simulation; The relationship between the length l and the thickness h of the shank (16) is: Where A1 is the first mode coefficient; c is the material sound velocity; f j is the natural frequency, which is 20kHz.

2. The device for electromagnetic induction heat treatment assisted bending vibration processing of internal threads according to claim 1 is characterized in that: The simulation includes: 1) Establishing an electromagnetic induction heating finite element model according to the material properties and dimensions of the workpiece (11) to be processed, simulating the heat affected zone of the workpiece (11) by changing the output power, electromagnetic induction output frequency, electromagnetic induction output current, spindle speed, feed rate and cross-sectional area of ​​the auxiliary heating rod (17) of the electromagnetic induction host (9), extracting the depth value of the corresponding temperature from the simulation result, the temperature is the effective softening temperature at which the material hardness of the workpiece (11) is reduced, and establishing the effective depth of the material hardness reduction of the workpiece (11), i.e., the back cutting amount a, by consulting relevant literature or corresponding experiments. p Regarding the output power P of the electromagnetic induction host (9) i 、Electromagnetic induction host output frequency f i 、Electromagnetic induction host output current I i , spindle speed n, feed rate v r and a multiple regression equation of the cross-sectional area S of the auxiliary heating rod (17); In the formula, α is the coefficient of the regression formula; a1, a2, a3, a4, a5, a6 are all parameter exponents; 2) According to the material properties and dimensions of the workpiece (11), the fine turning tool (13) and the internal thread turning tool (14), a finite element model of electromagnetic induction heating assisted cutting is established. By changing the amplitude A, the spindle speed n, the feed rate v r 、Back knife amount a p Simulate the cutting force during machining and establish the relationship between the cutting force and the amplitude A, spindle speed n, feed rate v r And back knife amount a p The multiple linear regression equation of In the formula, β, λ, ε, τ are all regression coefficients; The optimal machining parameters for internal thread turning using electromagnetic induction heat treatment assisted bending vibration were obtained through simulation.

3. The device for electromagnetic induction heat treatment assisted bending vibration processing of internal threads according to claim 1 or 2, characterized in that: The processing parameters include electromagnetic induction output power, electromagnetic induction host output frequency, electromagnetic induction host output current, vibration frequency, amplitude, spindle speed, feed rate, back cutting amount and auxiliary heating rod (17) model.

4. A method for machining internal threads by electromagnetic induction heat treatment assisted bending vibration, using the device for machining internal threads by electromagnetic induction heat treatment assisted bending vibration as claimed in claim 1, characterized in that: The process includes the following steps, which are performed in sequence: Step 1: Use ANSYS Workbench and Maxwell finite element simulation software to perform electromagnetic induction heating bidirectional coupling simulation and cutting simulation respectively, and establish the effective depth of material hardness reduction of the workpiece (11), that is, the back cutting amount a p Regarding the output power P of the electromagnetic induction host (9) i , the output frequency f of the electromagnetic induction host (9) i , the output current I of the electromagnetic induction host (9) i , the speed n of the high-speed spindle (1), the feed rate v of the high-speed spindle (1) r and the multivariate regression equation 1 of the cross-sectional area S of the auxiliary heating rod (17), and the cutting force with respect to the output vibration frequency f of the ultrasonic generator (3) j , the output amplitude A of the ultrasonic generator (3), the rotation speed n of the high-speed spindle (1), the feed rate v of the high-speed spindle (1) r And back knife amount a p The multivariate linear regression equation 2 is used to obtain the output power of the electromagnetic induction host (9), the output frequency of the electromagnetic induction host (9), the output current of the electromagnetic induction host (9), the output vibration frequency of the ultrasonic generator (3), the output amplitude of the ultrasonic generator (3), the rotation speed of the high-speed spindle (1), the feed rate of the high-speed spindle (1), the setting of the back cutting amount parameters and the optimal parameter value of the auxiliary heating rod (17) model, and input them into the bus control system and formulate a corresponding processing program; The relationship between the length l and the thickness h of the handle (16) is set to be: Where A1 is the first mode coefficient; c is the material sound velocity; f j is the natural frequency, which is 20kHz; Step 2: The workpiece (11) to be processed is mounted and fixed on the high-speed spindle (1), and the electromagnetic induction coil (10) is fixed on the workpiece (11) by adjusting the telescopic rod and the folding rod (4) of the cylinder (2), and the distance between the electromagnetic induction coil (10) and the workpiece (11) is adjusted; Step 3: Turn on the bus control system to control the CNC X-axis (8), the CNC Y-axis (9), the turret and the telescopic rod of the cylinder (2), return the machine tool to zero and calibrate the tool; turn on the electromagnetic induction host (9), set the output power, output frequency and output current, and the fixed heating area of ​​the electromagnetic induction coil (10) on the workpiece (11) is circular, and the center of the circle coincides with the main axis; Step 4: Start the processing program in the bus control system, and use the precision turning tool (13) to perform electromagnetic induction heating-assisted inner hole precision turning processing; Step 5: After the inner hole fine turning process is completed, the CNC X-axis (8) is controlled to return to zero through the bus control system, and the cutter head (5) is controlled to switch the fine turning tool (13) to the auxiliary heating rod (17) to perform heating pretreatment on the hole wall; Step 6: After the hole wall is heated and pretreated for a set time, the bus control system controls the numerical control X axis (8) to return to zero again, and controls the tool disc (5) to switch the auxiliary heating rod (17) to the internal thread turning tool (14), and at the same time turns on the ultrasonic generator (3), sets the output amplitude and frequency, and because the length l and thickness h of the tool handle (16) are set, high-frequency bending vibration can be generated, and the tool tip of the internal thread turning tool (14) can be driven to realize high-frequency micro-displacement swing in the XY plane with the tool handle (16) as the center under the axial vibration of the piezoelectric transducer (15), while coupling the macroscopic machining trajectories of the X-axis and the Y-axis, and performing electromagnetic induction heat treatment assisted bending vibration internal thread turning processing on the workpiece (11); At this point, a method for electromagnetic induction heat treatment assisted bending vibration processing of internal threads is completed.

5. The method for machining internal threads by electromagnetic induction heat treatment assisted bending vibration according to claim 4, characterized in that: The electromagnetic induction heating bidirectional coupling simulation is specifically as follows: According to the material properties and size of the workpiece (11) to be processed, the electromagnetic induction heating finite element model is established using ANSYS Workbench finite element simulation software. By changing the output power P of the electromagnetic induction host (9), the electromagnetic induction heating finite element model is obtained. i , the output frequency f of the electromagnetic induction host (9) i , the output current I of the electromagnetic induction host (9) i , the speed n of the high-speed spindle (1), the feed rate v of the high-speed spindle (1) r and the cross-sectional area S of the auxiliary heating rod (17), the heat-affected zone of the workpiece (17) is simulated, and the depth value of the corresponding temperature is extracted from the simulation result. The temperature is the effective softening temperature at which the material hardness of the workpiece (17) is reduced. The established multivariate regression equation is determined by consulting relevant literature or corresponding experiments: In the formula, α is the coefficient of the regression formula; a1, a2, a3, a4, a5, and a6 are all parameter exponents.

6. The method for machining internal threads by electromagnetic induction heat treatment assisted bending vibration according to claim 5, characterized in that: The output current of the electromagnetic induction host (9), the output frequency of the electromagnetic induction host (9) in steps 3, 4 and 6, and the setting of the hole wall heating pretreatment time in step 5 are all obtained through the simulation of the heat affected zone of the workpiece (17) in step 1.

7. The method for machining internal threads by electromagnetic induction heat treatment assisted bending vibration according to claim 4, characterized in that: The cutting simulation is specifically: The electromagnetic induction heating assisted cutting finite element model is established according to the material properties and dimensions of the workpiece (11) to be processed, the fine turning tool (13) and the internal thread turning tool (14), and the output amplitude A of the ultrasonic generator (3), the rotation speed n of the high-speed spindle (1), the feed rate v of the high-speed spindle (1) are changed. r 、Back knife amount a p The cutting force during processing is simulated, and the established multivariate linear regression equation is: In the formula, β, λ, ε, τ are all regression coefficients, is the cutting force.

8. The method for machining internal threads by electromagnetic induction heat treatment assisted bending vibration according to claim 4, characterized in that: In step three, the electromagnetic induction host (9) receives the instruction of the bus control system and generates current to heat the electromagnetic induction coil (10).

9. The method for machining internal threads by electromagnetic induction heat treatment assisted bending vibration according to claim 4, characterized in that: In step six, the ultrasonic generator (3) receives the command of the bus control system and generates an electrical signal to enable the piezoelectric transducer (15) to drive the internal thread turning tool (14) to vibrate at a high frequency.

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