A cryogenic medium internal spray type double swing head high-speed five-axis gantry machining center

Abstract

A cryogenic medium internal spray type double-swivel head high-speed five-axis gantry machining center is disclosed. The cryogenic medium is jetted from the tool tip to the tool head through a hollow channel formed by the double swivel head, electric spindle, and tool holder, integrating with the main body of the gantry machining center to achieve the design of a cryogenic medium internal spray type double-swivel head five-axis high-speed machining center. The cryogenic medium delivery pipeline inside the double swivel head spindle adopts a vacuum insulation structure, and heat insulation material is used at the interruption points to effectively limit the adverse effects of cryogenic temperature on the double swivel head spindle. In the double swivel head and electric spindle structure, the stationary vacuum hose and the rotating vacuum mandrel are connected by a rotary sealing joint to prevent leakage of the cryogenic medium at the dynamic-static gap, ensuring the normal operation of the double swivel head spindle. The cryogenic medium delivery pipeline passes through the center of the swivel head and electric spindle, achieving reliable medium transmission while avoiding interference with the movement of the double swivel head. The cryogenic medium delivery jet control device realizes stable regulation of the cooling medium flow rate and pressure during machining.

Description

Technical Field

[0001] This invention belongs to the field of CNC machine tool technology and relates to a high-speed five-axis gantry machining center with ultra-low temperature medium internal spray double swing head. Background Technology

[0002] In aerospace, shipping, and other fields, there is a wide variety of large, difficult-to-machine complex curved surface components, such as fiber-reinforced composite aircraft skins and high-temperature alloy turbine disks for heavy industrial gas turbines. Due to their large size and complex shapes, these components are generally machined using five-axis gantry machining centers. However, conventional cooling processes for typical difficult-to-machine materials such as fiber-reinforced composites and high-temperature alloys often result in high cutting temperatures, poor surface quality, rapid tool wear, and limited cutting speeds, creating an urgent need for powerful cooling and high-speed cutting. Ultra-low temperature spindle internal spray cooling high-speed machining using liquid nitrogen (-196℃) or similar coolants is an emerging high-performance manufacturing technology. It not only provides efficient and precise powerful cooling to the cutting area but also significantly increases cutting speeds by substantially reducing cutting temperatures.

[0003] Therefore, the cryogenic medium internal spray type double-swivel head high-speed five-axis gantry machining center has become a key piece of equipment for realizing the cryogenic high-speed machining of large, difficult-to-machine complex curved surface components. However, the development of this gantry machining center faces many challenges. For example, the diversity of materials and structures of the parts being machined requires multi-variable, wide-range, and quantitative control capabilities for the cryogenic medium; the double-swivel head spindle has significantly more degrees of freedom than a single spindle, which not only increases the design difficulty of the cryogenic medium delivery pipeline, but also increases the number of dynamic and static mating surfaces in the transmission path, placing extremely high demands on the cryogenic dynamic seal. Once the cryogenic medium leaks or there is a lack of effective heat insulation measures, it will lead to severe frost formation on the swivel head and spindle, structural deformation, failure of fit and lubrication, and even irreversible damage, making it impossible to guarantee its reliable operation. Therefore, overcoming the above challenges is extremely important for the development of the cryogenic medium internal spray type double-swivel head high-speed five-axis gantry machining center.

[0004] Currently, various machining equipment has been invented by domestic and foreign institutions for ultra-low temperature medium spindle internal spray cooling machining. In 2018, Dalian University of Technology disclosed "An Ultra-Low Temperature Medium Internal Spray CNC Machine Tool" in invention patent 201810144333.X. This machine tool integrates the liquid nitrogen internal spray cooling function with the spindle and machine tool structure. However, the machine tool involved is a three-axis vertical milling machine with a mechanical spindle and no automatic tool change. In 2019, Ehsan Tahmasebi of the University of British Columbia, Canada, published an article entitled "CFD and experimental analysis of the coolant flow incryogenic milling" in Volume 140, Issue 2 of the *International Journal of Machine Tools and Manufacture*, describing a machining equipment that can realize ultra-low temperature medium internal spray cooling. However, in this equipment, the ultra-low temperature medium is introduced from the side of the tool holder and does not pass through the spindle. Furthermore, the jet flow of the ultra-low temperature medium cannot be controlled, resulting in problems such as poor machine tool integration, inability to automatically change tools, and uncontrollable jet flow. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies or practical application needs by proposing a cryogenic medium internal spray type double-swivel head high-speed five-axis gantry machining center. It solves the problems of cryogenic medium transmission, heat insulation and dynamic sealing in the double-swivel head spindle. The machine tool has cryogenic medium transmission and jet control functions, and completes the effective integration of cryogenic medium internal spray cooling and double-swivel head five-axis gantry machining center, realizing cryogenic high-speed machining of large and difficult-to-machine materials and complex components.

[0006] The technical solution of the present invention:

[0007] A high-speed five-axis gantry machining center with an internal spray of cryogenic medium and a double-swivel head is mainly composed of three parts: a cryogenic medium transmission jet control device I, a five-axis gantry machining center machine tool body II, and a cryogenic medium internal spray double-swivel head spindle III.

[0008] When assembling the aforementioned cryogenic medium transfer jet control device I, the cryogenic medium storage tank 1.1 is placed on the left side of the machine tool. The first outlet 1.a of the cryogenic medium storage tank 1.1 is connected to the first port 1.b of the first vacuum hose 1.4 via the first nut 1.3. One end of the first vacuum tube 1.6 is connected to the first vacuum hose 1.4 via the first flange 1.5, and the other end is connected to the second vacuum tube 1.10 via the second flange 1.9. A first pressure sensor 1.7 and a temperature sensor 1.8 are sequentially sealed and installed in the middle of the first vacuum tube 1.6 to detect the cryogenic medium transfer pressure and temperature. The other end of the second vacuum tube 1.10 is connected to the third vacuum tube 1.16 via the third flange 1.13, and the middle of the second vacuum tube 1.10 is connected to the electric regulating valve 1.12 via the fourth flange 1.11 to regulate the cryogenic medium transfer flow rate. This supports the electric regulating valve. The baffle 1.15 of valve 1.12 is welded to the control unit housing 1.14; the other end of the third vacuum tube 1.16 is connected to the differential pressure flow meter 1.20 via the fifth flange 1.18 to detect the flow rate of the cryogenic medium; a safety valve 1.17 is sealed and installed in the middle of the third vacuum tube 1.16; one end of the fourth vacuum tube 1.21 is connected to the differential pressure flow meter 1.20 via the sixth flange 1.19, and the other end is connected to the pressure reducing valve 1.23 via the second nut 1.c to adjust the cryogenic medium transmission pressure; a second pressure sensor 1.22 is sealed and installed in the middle of the fourth vacuum tube 1.21; the other end of the pressure reducing valve 1.23 is connected to the fifth vacuum tube 1.24 via the third nut 1.d; the control module 1.26 is welded to the control unit housing 1.14; all connecting threads are reinforced with sealing tape, and polyurethane foam spray is used to insulate and heat-insulate all pipe connections;

[0009] When assembling the main body II of the five-axis gantry machining center, following the conventional machine tool assembly process, the worktable 2.1 is placed between the two Y-axis guide rails 2.2, and the Y-axis slide 2.3 is assembled with the Y-axis guide rail 2.2 through the guide rail groove; the column 2.4 is assembled and fixed on the Y-axis slide 2.3, and the crossbeam 2.5 is fixed to the column 2.4; the tool magazine 2.6 is fixed to the right side of the crossbeam 2.5; the X-axis slide 2.9 is installed on the X-axis guide rail 2.7 through the guide rail groove, and the X-axis guide rail 2.7 is fixed to the crossbeam 2.5; the Z-axis guide rail 2.8 is installed on the X-axis slide 2.9.

[0010] When assembling the double-swing head portion of the ultra-low temperature medium internal spray type double-swing head spindle III, the spindle box 3.7 and the first vacuum spindle 3.11 are fixedly connected by bolts, allowing the spindle box 3.7 to rotate around the A-axis; the first vacuum spindle 3.11 and the third vacuum hose 3.9 are connected by a threaded connection via a first copper connector 3.10; the first vacuum spindle 3.11 is connected to the housing 3.8 via a first deep groove ball bearing 3.12, wherein the inner ring of the bearing has a transition fit with the first vacuum spindle 3.11, and the outer ring of the bearing has a transition fit with the housing 3.8; the first bearing end cover 3.13 is pressed against the outer ring of the first deep groove ball bearing 3.12; the A-axis torque motor stator 3.14 is fixed on the first motor base 3.16, and the first motor base... 3.16 is fastened to housing 3.8; the A-axis torque motor rotor 3.15 is fixed on the first vacuum spindle 3.11, wherein the A-axis torque motor stator 3.14 and the A-axis torque motor rotor 3.15 are in clearance fit, and the encoder 3.18 is connected to the first motor base 3.16; the second low-temperature resistant rotary dynamic seal joint 3.17 is connected to the first vacuum spindle 3.11 by thread, with the rotating end connected to the first vacuum spindle 3.11 and the stationary end connected to the center hole of the A-axis rear end cover 3.19; the A-axis rear end cover 3.19 is fixed to the first motor base 3.16, and the fourth vacuum hose 3.21 is inserted into the hole 3.d of the A-axis rear end cover and connected to the stationary end of the second low-temperature resistant rotary dynamic seal joint 3.17 by thread; the second deep groove ball bearing 3.24 is connected with a transition... The second copper connector 3.22 is threaded onto the upper cylindrical surface 3.c of the housing 3.8; one end of the second copper connector 3.22 is connected to the fourth vacuum hose 3.21, and the other end is connected to the second vacuum spindle 3.23; the bottom of the second vacuum spindle 3.23 is bolted to the upper plane 3.b of the housing 3.8, while simultaneously pressing the inner ring of the second deep groove ball bearing 3.24; then the protective plate 3.20 is bolted to the housing 3.8; next, the C-axis torque motor stator 3.27 is bolted to the second motor mount 3.28; the second motor mount 3.28 is connected and fixed to the transition plate 3.25; the transition plate 3.25 is fitted along the second deep groove ball bearing 3.24 in a transition fit. Push the outer ring of the second deep groove ball bearing 3.24 into place until the transition plate groove surface 3.a presses against the outer ring of the second deep groove ball bearing 3.24. At this point, the second vacuum mandrel 3.23 and the center hole of the transition plate 3.25 are in clearance fit. Install the C-axis torque motor rotor 3.26 on the second vacuum mandrel 3.23, and then fix the upper end cover 3.29 to the upper side of the second motor base 3.28 by bolt connection. Push the second bearing housing 3.31 into the center hole of the upper end cover 3.29 and fix it to the upper end cover 3.29 by bolt connection. Assemble the third deep groove ball bearing 3.30 between the second bearing housing 3.31 and the second vacuum mandrel 3.23 in a transition fit. Connect the third low-temperature resistant rotary dynamic seal joint 3.32 to the second vacuum mandrel 3.23 by thread.23 is connected, with the stationary end connected to the center hole of the second bearing end cap 3.33; finally, the second bearing end cap 3.33 is used to press down on the outer ring of the third deep groove ball bearing 3.30 and fix it to the second bearing seat 3.31; it should be noted that the structure on the left side of the double swing head, which is not described in detail, is completely consistent with the structure on the right side mentioned above in some aspects. To avoid being too lengthy, it will not be described again.

[0011] When assembling the electric spindle part of the cryogenic medium internal spray type double swing head spindle III, the cryogenic medium internal spray type electric spindle 3.1 is fixed to the spindle box 3.7. The internal broach structure of the spindle is a vacuum partition pull rod 3.5, which solves the heat insulation problem when the cryogenic medium is transmitted in the spindle. One end of the vacuum partition pull rod 3.5 is connected to the pull claw 3.4, and the other end is connected to the third vacuum hose 3.9 through the first cryogenic resistant rotary dynamic seal joint 3.6. The connection is a threaded connection.

[0012] When assembling the main body II of the five-axis gantry machining center with the ultra-low temperature medium internal spray type double swing head spindle III, the second motor base 3.28 is fixed to the Z-guide rail 2.8;

[0013] When the cryogenic medium transmission jet control device I is assembled with the cryogenic medium internal spray type double swing head spindle III, one end of the second vacuum hose 1.27 is connected to the fifth vacuum hard tube 1.24 through the seventh flange 1.25, and the other end is inserted into the center hole of the second bearing end cover 3.33 and connected to the third cryogenic resistant rotary dynamic seal joint 3.32 through a thread.

[0014] When the aforementioned cryogenic medium internal spray type double swivel head high-speed five-axis gantry machining center is working, the machine tool is first started, and the cryogenic medium internal spray type double swivel head spindle III is rotated; then the shut-off valve 1.2 on the cryogenic medium storage tank 1.1 is opened, and the cryogenic medium passes sequentially through the cryogenic medium transmission jet control device I, the second vacuum hose 1.27, the third cryogenic resistant rotary dynamic seal joint 3.32, the second vacuum mandrel 3.23, the fourth vacuum hose 3.21, the A-axis rear end cover 3.19, the second cryogenic resistant rotary dynamic seal joint 3.17, the first vacuum mandrel 3.11, the second vacuum hose 3.9, and the first cryogenic resistant rotary dynamic seal joint 3.6; finally, it enters the cryogenic medium internal spray type electric spindle 3.1, and then is ejected from the end of the tool 3.2 through the vacuum partition pull rod 3.5 and the tool holder 3.3, and machining can then begin.

[0015] The beneficial effects of this invention are as follows: the cryogenic medium flows through the hollow channel of the double-swivel head, electric spindle, and tool holder, ultimately jetting from the tool tip to the tool end and integrating with the main body of the gantry machining center, realizing the independent design of a cryogenic medium internally sprayed double-swivel head five-axis high-speed machining center; the cryogenic medium delivery pipeline inside the double-swivel head spindle adopts a vacuum insulation structure, and heat insulation material is used at the interruption point, effectively limiting the adverse effects of cryogenic temperature on the double-swivel head spindle; in the double-swivel head and electric spindle structure, the stationary vacuum hose and the rotating vacuum spindle are connected by a cryogenic-resistant rotary dynamic sealing joint, preventing the leakage of cryogenic medium at the dynamic-static gap, thereby ensuring the normal operation of the double-swivel head spindle; the cryogenic medium delivery pipeline passes through the center of the swivel head and electric spindle, achieving reliable medium transmission while avoiding interference with the movement of the double-swivel head; the electric spindle adopts a vacuum-insulated tie rod, which not only realizes automatic tool changing but also provides heat insulation; the cryogenic medium delivery jet control device realizes stable regulation of the cooling medium flow rate and pressure during machining. Attached Figure Description

[0016] Figure 1 A schematic diagram of a high-speed five-axis gantry machining center with internal spray of cryogenic medium and double swing head.

[0017] Figure 2 This is a top view of a high-speed five-axis gantry machining center with an internal spray of cryogenic medium and double swing head.

[0018] Figure 3 A schematic diagram of a double-swivel head spindle structure with internal spray for cryogenic medium;

[0019] Figure 4 This is an alternative embodiment of a cryogenic medium internal spray type double swing head high-speed five-axis gantry machining center.

[0020] In the diagram: Ⅰ-Cryogenic medium transmission jet control device; Ⅱ-Five-axis gantry machining center main body; Ⅲ-Cryogenic medium internal spray type double-swivel head spindle; 1.1-Cryogenic medium storage tank; 1.2-Stop valve; 1.3-First nut; 1.4-First vacuum hose; 1.5-First flange; 1.6-First vacuum tube; 1.7-First pressure sensor; 1.8-Temperature sensor; 1.9-Second flange; 1.10-Second vacuum tube; 1.11-Fourth flange; 1.12-Electric regulating valve; 1.13-Third flange; 1.14-Control unit box; 1.15-Baffle; 1.16-Third vacuum tube; 1.17 - Safety Valve; 1.18 - Fifth Flange; 1.19 - Sixth Flange; 1.20 - Differential Pressure Flow Meter; 1.21 - Fourth Vacuum Rigid Tube; 1.22 - Second Pressure Sensor; 1.23 - Pressure Reducing Valve; 1.24 - Fifth Vacuum Rigid Tube; 1.25 - Seventh Flange; 1.26 - Control Module; 1.27 - Second Vacuum Hose; 1.a - First Liquid Outlet; 1.b - First Port; 1.c - Second Nut; 1.d - Third Nut; 2.1 - Workbench; 2.2 - Y-Guide Rail; 2.3 - Slide Ram; 2.4 - Column; 2.5 - Crossbeam; 2.6 - Tool Magazine; 2.7 - X-Guide Rail; 2.8 - Z-Guide Rail 2.9-Slide saddle; 3.1-Cryogenic medium internal injection type electric spindle; 3.2-Cutting tool; 3.3-Tool holder; 3.4-Draw claw; 3.5-Vacuum partition tie rod; 3.6-First cryogenic rotary dynamic seal joint; 3.7-Spindle box; 3.8-Box body; 3.9-Third vacuum hose; 3.10-First copper connector; 3.11-First vacuum mandrel; 3.12-First deep groove ball bearing; 3.13-First bearing end cover; 3.14-A-axis torque motor stator; 3.15-A-axis torque motor rotor; 3.16-First motor base; 3.17-Second cryogenic rotary dynamic seal joint; 3.18-Encoder; 3.19 - A-axis rear end cover; 3.20-protective plate; 3.21-fourth vacuum hose; 3.22-second copper connector; 3.23-second vacuum mandrel; 3.24-second deep groove ball bearing; 3.25-transition disc; 3.26-C-axis torque motor rotor; 3.27-C-axis torque motor stator; 3.28-second motor base; 3.29-upper end cover; 3.30-third deep groove ball bearing; 3.31-second bearing housing; 3.32-third low-temperature resistant rotary dynamic seal joint; 3.33-second bearing end cover; 3.a-transition disc groove surface; 3.b-upper side plane of the housing; 3.c-upper side cylindrical surface of the housing; 3.d-A-axis rear end cover hole. Detailed Implementation

[0021] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings and technical solutions.

[0022] In this embodiment, the cryogenic medium is liquid nitrogen, with a minimum temperature of -196℃; the cryogenic medium storage tank 1.1 is a DPL medium-pressure series self-pressurizing Dewar tank with a working pressure of 1.2MPa and a nominal volume of 175L; the ranges of the first pressure sensor 1.7 and the second pressure sensor 1.22 are 0~2.0MPa; the temperature sensor 1.8 has a range of -200~50℃; the electric regulating valve 1.12 is an 810D top-guided single-seat regulating valve with a linear adjustment range of 0~100L / h; the safety valve 1.17 has a set threshold pressure of 2.4MPa; the differential pressure flow meter 1.20 is a WRV standard cone flow meter with a range of 0~100L / h; the pressure reducing valve 1.23 is a diaphragm pressure reducing valve with an adjustment range of 0.1~2.0MPa; the thermal conductivity of the vacuum structure is 2×10⁻⁶. -5 W / (m·K); The thermal insulation treatment at the pipe connection is achieved by spraying polyurethane foam, with a thermal conductivity of 0.024 W / (m·K); The travel of the X / Y / Z axes of the gantry machining center is 3000 / 2000 / 1000 mm, the maximum rapid traverse speed of the X / Y / Z axes is 24000 mm / min, the positioning accuracy of the X / Y / Z axes is 0.008 mm, the repeatability of the X / Y / Z axes is 0.006 mm, the rotation range of the A / C axes is ±110° / ±360°, and the maximum speed of the A / C axes is 60 The A / C axis positioning accuracy is 6″, and the A / C axis repeatability is 5″. The tool holder 3.3 compatible with the cryogenic medium internal injection electric spindle 3.1 is HSK-A63, with a maximum speed of 21000rpm, a power of 35kW, and a torque of 80Nm. The tool magazine 2.6 has a capacity of 30 tools. The rotating and stationary end face materials of the first cryogenic rotary dynamic seal joint 3.6, the second cryogenic rotary dynamic seal joint 3.17, and the third cryogenic rotary dynamic seal joint 3.32 are ceramic, and the spring stiffness coefficient is 10N / m.

[0023] The assembly process of the cryogenic medium internal spray type double-swivel head high-speed five-axis gantry machining center is as follows: (see attached) Figure 1 , 2As shown in Figure 3, the first step is to place the cryogenic medium storage tank 1.1 filled with liquid nitrogen in the predetermined position and observe whether the readings of the liquid level gauge and pressure sensor on the tank are normal. If they are normal, continue the installation; if they are abnormal, replace the liquid nitrogen storage tank. Connect the first port 1.b of the first vacuum hose 1.4 to the first outlet 1.a through the self-contained first nut 1.3. Then weld the partition 1.15 inside the control unit box 1.14. After that, connect one end of the first vacuum tube 1.6 to the first vacuum hose 1.4 through the first flange 1.5, and the other end to the second vacuum tube 1.10 through the second flange 1.9. The first pressure sensor 1.7 and temperature sensor 1.8 are sequentially sealed and installed in the middle of the first vacuum tube 1.6. Connect the other end of the second vacuum tube 1.10 to the third vacuum tube 1.16 through the third flange 1.13. Connect the middle of the second vacuum tube 1.10 through the fourth flange 1.9. Connect flange 1.11 to electric regulating valve 1.12; fix electric regulating valve 1.12 to partition plate 1.15 with bolts; connect the other end of third vacuum tube 1.16 to differential pressure flow meter 1.20 through fifth flange 1.18, wherein safety valve 1.17 is sealed and installed in the middle of third vacuum tube 1.16; connect one end of fourth vacuum tube 1.21 to differential pressure flow meter 1.20 through sixth flange 1.19, and the other end to pressure reducing valve 1.23 through second nut 1.c, wherein second pressure sensor 1.22 is sealed and installed in the middle of fourth vacuum tube 1.21; connect the other end of pressure reducing valve 1.23 to fifth vacuum tube 1.24 through third nut 2.d; then weld control module 1.26 to control unit box 1.14. All the above vacuum tubes should be kept as horizontal as possible during installation; thus, the assembly of cryogenic medium transmission jet control device I is completed.

[0024] The second step involves placing the worktable 2.1 between the two sides of the Y-axis guide rail 2.2, and assembling the Y-axis slide 2.3 with the Y-axis guide rail 2.2 via the guide rail groove; assembling and fixing the column 2.4 onto the Y-axis slide 2.3, and fixing the crossbeam 2.5 onto the column 2.4; fixing the tool magazine 2.6 to the right side of the crossbeam 2.5; installing the X-axis slide 2.9 onto the X-axis guide rail 2.7 via the guide rail groove, and fixing the X-axis guide rail 2.7 onto the crossbeam 2.5; and installing the Z-axis guide rail 2.8 onto the X-axis slide 2.9; thus, the assembly of the main body II of the five-axis gantry machining center is completed.

[0025] The third step involves fixing the spindle box 3.7 to the first vacuum spindle 3.11 using bolts, allowing the spindle box 3.7 to rotate around axis A. The first vacuum spindle 3.11 is then connected to the third vacuum hose 3.9 via a first copper connector 3.10 using a threaded connection. The first vacuum spindle 3.11 is then connected to the housing 3.8 using a first deep groove ball bearing 3.12, with the inner ring of the bearing having a transition fit with the first vacuum spindle 3.11 and the outer ring having a transition fit with the housing 3.8. Next, the first bearing end cap 3.13 is pressed against the outer ring of the first deep groove ball bearing 3.12. Then, the stator 3.14 of the A-axis torque motor is fixed to the first motor mount 3.16, and the first motor mount 3.16 is tightened to the housing 3.8. Finally, the A-axis torque motor stator 3.14 is... The rotor 3.15 of the A-axis torque motor is fixed on the first vacuum spindle 3.11, wherein the stator 3.14 of the A-axis torque motor is clearance-fitted with the rotor 3.15 of the A-axis torque motor, and the encoder 3.18 is connected to the first motor mount 3.16; the second low-temperature resistant rotary dynamic seal joint 3.17 is threaded, with its rotating end connected to the first vacuum spindle 3.11 and its stationary end connected to the center hole of the A-axis rear end cover 3.19; the A-axis rear end cover 3.19 is fixed to the first motor mount 3.16, and the fourth vacuum hose 3.21 is inserted into the hole 3.d of the A-axis rear end cover and threadedly connected to the stationary end of the second low-temperature resistant rotary dynamic seal joint 3.17; the second deep groove ball bearing 3.24 is installed in the housing 3.8 with an transition fit. On the upper cylindrical surface 3.c of the body; using a threaded connection, one end of the second copper connector 3.22 is connected to the fourth vacuum hose 3.21, and the other end is connected to the second vacuum spindle 3.23; the bottom of the second vacuum spindle 3.23 is fixed to the upper side plane 3.b of the housing 3.8 with bolts, while simultaneously pressing the inner ring of the second deep groove ball bearing 3.24; then the protective plate 3.20 is fixed to the housing 3.8 with bolts; next, the C-axis torque motor stator 3.27 is fixed to the second motor mount 3.28 with bolts; the second motor mount 3.28 is connected and fixed to the transition plate 3.25; the transition plate 3.25 is pushed in along the outer ring of the second deep groove ball bearing 3.24 with an transition fit, straight... The outer ring of the second deep groove ball bearing 3.24 is pressed against the groove surface 3.a of the transition plate. At this time, the second vacuum spindle 3.23 and the center hole of the transition plate 3.25 are in clearance fit with a clearance of 0.1mm. The C-axis torque motor rotor 3.26 is installed on the second vacuum spindle 3.23, and then the upper end cover 3.29 is fixed to the upper side of the second motor base 3.28 by bolt connection. The second bearing housing 3.31 is pushed into the center hole of the upper end cover 3.29 and fixed to the upper end cover 3.29 by bolt connection. The third deep groove ball bearing 3.30 is assembled between the second bearing housing 3.31 and the second vacuum spindle 3.23 in a transition fit. The third low-temperature resistant rotary dynamic seal joint 3.32 is connected to the second vacuum spindle 3.23 by thread on the rotating end.Connect 23, with the stationary end connected to the center hole of the second bearing end cap 3.33; finally, use the second bearing end cap 3.33 to press down on the outer ring of the third deep groove ball bearing 3.30 and fix it to the second bearing seat 3.31; thus, the assembly of the double-swivel head part in the cryogenic medium internal spray type double-swivel head spindle III is completed.

[0026] The fourth step is to fix the cryogenic medium internal spray type electric spindle 3.1 to the spindle box 3.7. The internal broach structure of the spindle is a vacuum partition pull rod 3.5. One end of the vacuum partition pull rod 3.5 is connected to the pull claw 3.4, and the other end is connected to the third vacuum hose 3.9 through the first cryogenic resistant rotary dynamic seal joint 3.6. The connection is a threaded connection. At this point, the assembly of the electric spindle part of the cryogenic medium internal spray type double swing head spindle III is completed.

[0027] Fifth step, fix the second motor base 3.28 to the Z guide rail 2.8; at this point, the assembly of the five-axis gantry machining center machine tool body II and the cryogenic medium internal spray type double swivel head spindle III is completed;

[0028] Step 6: Connect one end of the second vacuum hose 1.27 to the fifth vacuum tube 1.24 through the seventh flange 1.25, and insert the other end into the center hole of the second bearing end cap 3.33, and connect it to the third low-temperature resistant rotary dynamic seal joint 3.32 through threads; at this point, the assembly of the cryogenic medium transmission jet control device I and the cryogenic medium internal spray type double swing head spindle III is completed.

[0029] When the five-axis high-speed gantry machining center with internally sprayed cryogenic medium spindle is in operation, the machine tool is first started, and the internally sprayed cryogenic medium spindle III is rotated. Then, the shut-off valve 1.2 on the cryogenic medium storage tank 1.1 is opened, and the cryogenic medium passes sequentially through the cryogenic medium transmission jet control device I, the second vacuum hose 1.27, the third cryogenic resistant rotary dynamic seal joint 3.32, the second vacuum mandrel 3.23, the fourth vacuum hose 3.21, the A-axis rear end cover 3.19, the second cryogenic resistant rotary dynamic seal joint 3.17, the first vacuum mandrel 3.11, the second vacuum hose 3.9, and the first cryogenic resistant rotary dynamic seal joint 3.6. Finally, it enters the internally sprayed cryogenic medium electric spindle 3.1, and then passes through the vacuum partition pull rod 3.5 and the tool holder 3.3, and is ejected from the end of the tool 3.2. The flow rate is about 30 to 50 L / h, and the temperature is about -196 to -180℃, at which point machining can begin.

[0030] Obviously, the embodiments described above are only some, not all, of the embodiments in this application. For example, Figure 4An alternative embodiment of a cryogenic medium internal spray double-swivel head high-speed five-axis gantry machining center is presented, wherein the five-axis gantry machining center in this embodiment is replaced by a conventional five-axis machining center. Therefore, based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort should fall within the scope of protection of this application. In summary, the content of this specification should not be construed as a limitation of this application.

[0031] This invention employs a vacuum pipeline passing through the center of the double-swivel head and the electric spindle, and combines the motion transfer and cryogenic dynamic sealing functions of the low-temperature resistant rotary dynamic seal joint to achieve cryogenic internal spray cooling through the double-swivel head spindle. The reliable operation of the double-swivel head spindle is ensured by a rationally arranged cryogenic medium vacuum transmission pipeline. The invention effectively integrates a gantry machining center, double-swivel head, high-speed electric spindle, and cryogenic medium transmission control device, forming a complete structure of a cryogenic internal spray double-swivel head high-speed five-axis machining center, facilitating high-speed machining of various types of large-sized, complex structural parts with cryogenic cooling.

Claims

1. A cryogenic medium internal spray type double-swivel head high-speed five-axis gantry machining center, characterized in that, The cryogenic medium internal spray double-swivel high-speed five-axis gantry machining center is mainly composed of three parts: cryogenic medium transmission jet control device (Ⅰ), five-axis gantry machining center machine tool body (Ⅱ), and cryogenic medium internal spray double-swivel spindle (Ⅲ). Assembly of the cryogenic medium transfer jet control device (Ⅰ): The cryogenic medium storage tank (1.1) is placed on the left side of the machine tool. The first outlet (1.a) of the cryogenic medium storage tank (1.1) is connected to the first port (1.b) of the first vacuum hose (1.4) through the first nut (1.3); one end of the first vacuum tube (1.6) is connected to the first vacuum hose (1.4) through the first flange (1.5), and the other end is connected to the second vacuum tube (1.10) through the second flange (1.9). Connect; a first pressure sensor (1.7) and a temperature sensor (1.8) are sequentially and sealed in the middle of the first vacuum tube (1.6) to detect the pressure and temperature of the cryogenic medium transmission; the other end of the second vacuum tube (1.10) is connected to the third vacuum tube (1.16) via a third flange (1.13), and the middle of the second vacuum tube (1.10) is connected to the electric regulating valve (1.12) via a fourth flange (1.11) to regulate the cryogenic medium transmission flow rate; used to support the electric regulating valve. The partition plate (1.15) of (1.12) is welded to the control unit housing (1.14); the other end of the third vacuum tube (1.16) is connected to the differential pressure flow meter (1.20) through the fifth flange (1.18) to detect the flow rate of the cryogenic medium; a safety valve (1.17) is sealed and installed in the middle of the third vacuum tube (1.16); one end of the fourth vacuum tube (1.21) is connected to the differential pressure flow meter (1.20) through the sixth flange (1.19), and the other end is connected through the second nut (1.c). The pressure reducing valve (1.23) is connected to the pressure reducing valve (1.24) to regulate the transmission pressure of the cryogenic medium; the second pressure sensor (1.22) is sealed in the middle of the fourth vacuum tube (1.21); the other end of the pressure reducing valve (1.23) is connected to the fifth vacuum tube (1.24) through the third nut (1.d); the control module (1.26) is welded to the control unit box (1.14); all connecting threads are reinforced with sealing tape, and polyurethane foam spray is used to insulate and heat-insulate all connections of the pipeline; Assembly of the main body (II) of the five-axis gantry machining center: The worktable (2.1) is placed between the two Y-axis guide rails (2.2), and the Y-axis slide (2.3) is assembled with the Y-axis guide rail (2.2) through the guide rail groove; the column (2.4) is assembled and fixed on the Y-axis slide (2.3), and the crossbeam (2.5) is fixed on the column (2.4); the tool magazine (2.6) is fixed on the right side of the crossbeam (2.5); the X-axis slide (2.9) is installed on the X-axis guide rail (2.7) through the guide rail groove, and the X-axis guide rail (2.7) is fixed on the crossbeam (2.5); the Z-axis guide rail (2.8) is installed on the X-axis slide (2.9); Assembly of the double-swing head section in the cryogenic medium internal spray type double-swing head spindle (Ⅲ): The spindle box (3.7) and the first vacuum spindle (3.11) are fixedly connected by bolts, so that the spindle box (3.7) can rotate around the A-axis; the first vacuum spindle (3.11) and the third vacuum hose (3.9) are connected by a threaded connection through the first copper connector (3.10); the first vacuum spindle (3.11) is connected to the housing (3.8) through the first deep groove ball bearing (3.12), wherein the inner ring of the bearing is in transition fit with the first vacuum spindle (3.11), and the outer ring of the bearing is in transition fit with the housing (3.8); the first bearing end cover (3.13) is pressed against the outer ring of the first deep groove ball bearing (3.12); the A-axis torque motor stator ( 3.14) Fix the first motor base (3.16) to the first motor base (3.16), and the first motor base (3.16) is fastened to the housing (3.8); fix the A-axis torque motor rotor (3.15) to the first vacuum spindle (3.11), wherein the A-axis torque motor stator (3.14) and the A-axis torque motor rotor (3.15) are in clearance fit, and the encoder (3.18) is connected to the first motor base (3.16); connect the second low-temperature resistant rotary dynamic sealing joint (3.17) to the first vacuum spindle (3.11) through a threaded connection, with the rotating end connected to the first vacuum spindle (3.11) and the stationary end connected to the center hole of the A-axis rear end cover (3.19); fix the A-axis rear end cover (3.19) to the first motor base (3.16), and insert the fourth vacuum hose (3.21) into the A-axis. In the rear cover hole (3.d), the stationary end of the second low-temperature resistant rotary dynamic seal joint (3.17) is connected by thread; the second deep groove ball bearing (3.24) is installed on the upper cylindrical surface (3.c) of the housing (3.8) with an transition fit; one end of the second copper connector (3.22) is connected to the fourth vacuum hose (3.21) by thread, and the other end is connected to the second vacuum mandrel (3.23); the bottom of the second vacuum mandrel (3.23) is fixed to the upper plane (3.b) of the housing (3.8) by bolt connection, while pressing the inner ring of the second deep groove ball bearing (3.24); then the protective plate (3.20) is fixed to the housing (3.8) by bolt connection; the C-axis torque motor is installed. The stator (3.27) is fixed to the second motor mount (3.28) by bolt connection; the second motor mount (3.28) is connected and fixed to the transition plate (3.25); the transition plate (3.25) is pushed into the outer ring of the second deep groove ball bearing (3.24) in a transition fit until the groove surface (3.a) of the transition plate presses against the outer ring of the second deep groove ball bearing (3.24), at which time the second vacuum mandrel (3.23) and the center hole of the transition plate (3.25) are in clearance fit; the C-axis torque motor rotor (3.26) is installed on the second vacuum mandrel (3.23), and the upper end cover (3.29) is fixed to the upper side of the second motor mount (3.28) by bolt connection; the second bearing seat (3.31) is pushed into the upper end cover (3.28).29) The center hole is bolted to the upper end cap (3.29); the third deep groove ball bearing (3.30) is fitted between the second bearing housing (3.31) and the second vacuum mandrel (3.23) with an intermediate fit; the third low-temperature resistant rotary dynamic seal joint (3.32) is threaded, with the rotating end connected to the second vacuum mandrel (3.23) and the stationary end connected to the center hole of the second bearing end cap (3.33); finally, the second bearing end cap (3.33) is used to press the outer ring of the third deep groove ball bearing (3.30) and fix it to the second bearing housing (3.31); the structure on the left side of the double swing head is the same as the structure on the right side of the double swing head. Assembly of the electric spindle in the cryogenic medium internal spray type double swing head spindle (Ⅲ): The cryogenic medium internal spray type electric spindle (3.1) is fixed to the spindle box (3.7), wherein the spindle internal broach structure is a vacuum partition pull rod (3.5); one end of the vacuum partition pull rod (3.5) is connected to the pull claw (3.4), and the other end is connected to the third vacuum hose (3.9) through the first cryogenic resistant rotary dynamic seal joint (3.6), and the connection form is threaded connection; Assembly of the five-axis gantry machining center machine tool body (Ⅱ) and the ultra-low temperature medium internal spray type double swing head spindle (Ⅲ): fix the second motor base (3.28) and the Z guide rail (2.8); The cryogenic medium transmission jet control device (Ⅰ) is assembled with the cryogenic medium internal spray type double swing head spindle (Ⅲ): one end of the second vacuum hose (1.27) is connected to the fifth vacuum hard tube (1.24) through the seventh flange (1.25), and the other end is inserted into the center hole of the second bearing end cover (3.33) and connected to the third cryogenic resistant rotary dynamic seal joint (3.32) through thread.

2. The cryogenic medium internal spray type double-swivel head high-speed five-axis gantry machining center according to claim 1, characterized in that, When the cryogenic medium internal spray type double swivel head high-speed five-axis gantry machining center is working, the machine tool is first started, and the cryogenic medium internal spray type double swivel head spindle (Ⅲ) is rotated; then the shut-off valve (1.2) on the cryogenic medium storage tank (1.1) is opened, and the cryogenic medium passes through the cryogenic medium transmission jet control device I, the second vacuum hose (1.27), the third cryogenic resistant rotary dynamic seal joint (3.32), the second vacuum mandrel (3.23), the fourth vacuum hose (3.21), the A-axis rear end cover (3.19), the second cryogenic resistant rotary dynamic seal joint (3.17), the first vacuum mandrel (3.11), the third vacuum hose (3.9), and the first cryogenic resistant rotary dynamic seal joint (3.6) in sequence; finally, it enters the cryogenic medium internal spray type electric spindle (3.1), and then is ejected from the end of the tool (3.2) through the vacuum partition pull rod (3.5) and the tool holder (3.3), and machining can begin.

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