A liquid nitrogen nozzle control device

Abstract

The application relates to a liquid nitrogen spray pipe regulating device belonging to the technical field of cutting machining of difficult-to-machine materials, in particular to a liquid nitrogen super-low-temperature cooling temperature control machining system. The application provides a liquid nitrogen spray pipe regulating device. The liquid nitrogen spray pipe regulating device 1.7 comprises a magnetic solid block 4.1, wherein the magnetic solid block 4.1 is connected with the upper end of an upper connecting rod 4.2, the lower end of the upper connecting rod 4.2 is connected with a linear motor 4.5; a movable block 4.6 is connected with the movable end of the linear motor 4.5, the movable block 4.6 is connected with the upper end of a standard ruler 4.11, the movable block 4.6 is connected with the upper end of a lower connecting rod 4.8, the upper end of the lower connecting rod 4.8 is provided with a liquid nitrogen straight pipe 4.9, and the standard ruler 4.11 is provided with a protractor 4.14.

Description

Technical Field

[0001] This invention belongs to the field of machining technology for difficult-to-machine materials, and particularly relates to a liquid nitrogen cryogenic cooling temperature control machining system. Background Technology

[0002] Currently, cryogenic assisted cooling technology is increasingly widely used in the machining of difficult-to-machine materials for aerospace applications. Cryogenic cooling technology offers unique advantages such as improving the machining quality and efficiency of difficult-to-machine materials, reducing overall machining costs, extending tool life, and being environmentally friendly. Simultaneously, cryogenic cooling machining can reduce tool wear, improve chip breaking performance, and effectively avoid machining defects caused by excessively high or rapid temperature rise during cutting, while also improving dimensional accuracy and surface quality. With in-depth research into this technology, it has been found that it is necessary to optimize and precisely control the appropriate cooling temperature for different difficult-to-machine materials during machining. Furthermore, precise and rapid cooling temperatures need to be adjusted for different parts of the workpiece during the machining process.

[0003] Domestic research has been conducted on liquid nitrogen temperature control systems for machining processes. A domestic invention patent, application number CN202110410796.8, entitled "A System for Controlling Liquid Nitrogen Temperature, Pressure, and Additive Concentration Supply," describes a system that allows liquid nitrogen to enter a honeycomb-shaped porous structure through a main pipe. Here, liquid nitrogen and compressed air can mix well and uniformly, thereby achieving temperature regulation within the range of -196℃ to room temperature. However, this system can only preset the output liquid nitrogen temperature, which is insufficient to meet the need for rapid and flexible real-time control of liquid nitrogen cooling temperature during machining. Therefore, there is an urgent need to design a liquid nitrogen cryogenic cooling temperature control machining system, which requires the corresponding design of a liquid nitrogen nozzle control device. Summary of the Invention

[0004] The present invention addresses the above-mentioned problems by providing a liquid nitrogen nozzle control device.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: the liquid nitrogen nozzle control device 1.7 of the present invention includes a magnetic block 4.1, characterized in that the magnetic block 4.1 is connected to the upper end of the upper connecting rod 4.2, and the lower end of the upper connecting rod 4.2 is connected to the linear motor 4.5; the movable end of the linear motor 4.5 is connected to a movable block 4.6, the movable block 4.6 is connected to the upper end of the standard ruler 4.11, the movable block 4.6 is connected to the upper end of the lower connecting rod 4.8, a liquid nitrogen straight tube 4.9 is provided on the lower connecting rod 4.8, and a protractor 4.14 is provided on the standard ruler 4.11.

[0006] As a preferred embodiment, the magnetic block 4.1 of the present invention is connected to the upper end of the upper connecting rod 4.2 by an upper fastening screw 4.3, and the lower end of the upper connecting rod 4.2 is connected to the linear motor 4.5 by a lower fastening screw 4.4.

[0007] As another preferred embodiment, the movable block 4.6 of the present invention is connected to the upper end of the standard ruler 4.11 by the standard ruler fastening screw 4.12.

[0008] As another preferred embodiment, the movable block 4.6 of the present invention is connected to the upper end of the lower connecting rod 4.8 by a bolt group 4.7.

[0009] As another preferred embodiment, the lower connecting rod 4.8 of the present invention is provided with a mounting hole, through which the liquid nitrogen straight tube 4.9 passes. Threaded holes are provided around the mounting hole, and the front end of the liquid nitrogen straight tube fastening screw 4.10 abuts against the outer wall of the liquid nitrogen straight tube 4.9 through the threaded hole, thereby fixing the liquid nitrogen straight tube 4.9.

[0010] Secondly, the lower connecting rod 4.8 of the present invention includes a first connecting rod 5.2 and a second connecting rod 5.5. The first connecting rod 5.2 is provided with a mounting hole, and a fastening screw 4.10 is provided at the lower end of the first connecting rod 5.2. A protrusion is provided at the middle of the upper end of the first connecting rod 5.2. A connecting groove is provided at the middle of the lower end of the second connecting rod corresponding to the protrusion. A threaded hole is provided on the wall of the connecting groove. The front end of the fastening screw 5.4 of the first connecting rod is screwed through the threaded hole and abuts against the protrusion. The upper end of the second connecting rod 5.5 is connected to the movable block 4.6 through a bolt group 4.7. The upper part of the second connecting rod 5.5 is placed in the opening groove at the lower end of the movable block 4.6.

[0011] In addition, the upper connecting rod 4.2 of the present invention is provided with a strip-shaped opening 4.15 along the length direction of the upper connecting rod 4.2. The front end of the upper fastening screw 4.3 passes through the strip-shaped opening 4.15 and is screwed into the threaded hole on the magnetic block 4.1. The width of the head end of the upper fastening screw 4.3 is greater than the width of the strip-shaped opening 4.15.

[0012] The beneficial effects of this invention.

[0013] In use, the liquid nitrogen nozzle control device of this invention involves mounting an upper connecting rod 4.2 onto a magnetic block 4.1, fixing the upper connecting rod 4.2 to a linear motor 4.5, and fixing a movable block 4.6 to the movable end of the linear motor 4.5. A lower connecting rod 4.8 is then mounted on the other end of the movable block 4.6, forming a universal joint structure. The lower connecting rod 4.8 is rotatable and can be fixed. A standard ruler 4.11 is fixed to the movable block 4.6, and finally, a protractor 4.14 is mounted onto the standard ruler 4.11. Figure 3 The angle ruler structure shown is used to adjust the horizontal bar of the protractor 4.14 (i.e., Figure 3 When the horizontal bar is aligned with the axial direction of the liquid nitrogen straight tube 4.9 (using the thick solid line in the middle diagonal), the angle indicated by the protractor 4.14 is the liquid nitrogen jet angle (i.e., the angle indicated by the protractor 4.14). Figure 3 (Angle shown in the circle).

[0014] After determining the liquid nitrogen jet angle in the liquid nitrogen straight tube 4.9 according to process requirements, the liquid nitrogen nozzle control device 1.7 is adjusted. The standard ruler 4.11 is adjusted so that its long rod is horizontal to the side of the magnetic block 4.1; the liquid nitrogen straight tube 4.9 is rotated, and the protractor 4.14 on the standard ruler 4.11 is used to determine that the angle between the axis of the liquid nitrogen straight tube 4.9 and the standard ruler 4.11 is equal to the preset spray angle; then, the upper connecting rod 4.2 is rotated so that the angle between the upper connecting rod 4.2 and the side of the magnetic block 4.1 is also equal to the set liquid nitrogen angle; finally, the entire liquid nitrogen nozzle control device 1.7 is attached to the side of the machine tool spindle box by the magnetic block 4.1.

[0015] Adjust the universal joint angle of the lower connecting rod 4.8 so that the axis of the straight rod 1.8 and the cutter 2.3 are on the same straight line, that is, the nozzle is aligned with the cutter tip. Adjust the distance between the liquid nitrogen straight tube 4.9 and the cutter tip to the set distance.

[0016] As can be seen from the above, the liquid nitrogen nozzle control device of the present invention can reliably and accurately control the liquid nitrogen injection angle and position, and the device is low in cost and easy to use. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. The scope of protection of the present invention is not limited to the following description.

[0018] Figure 1 —Diagram of the liquid nitrogen nozzle control device of the present invention, wherein: 4.1-magnetic block, 4.2-upper connecting rod, 4.3-upper fastening screw, 4.4-lower fastening screw, 4.5-linear motor, 4.6-moving block, 4.7-bolt group, 4.8-lower connecting rod, 4.9-liquid nitrogen straight pipe, 4.10-liquid nitrogen straight pipe fastening screw, 4.11-standard ruler, 4.12-standard ruler fastening screw, 4.13-protractor fastening screw, 4.14-protractor, 4.15-strip opening.

[0019] Figure 2 —Diagram of the movable joint of the liquid nitrogen straight tube in this invention ( Figure 2 for Figure 1 (Cross-sectional view), where: 5.2 - first connecting rod, 5.4 - first connecting rod fastening screw, 5.5 - second connecting rod.

[0020] Figure 3 —Schematic diagram of the use of the protractor and standard ruler of this invention.

[0021] Figure 4—Diagram of the cryogenic milling system of this invention, wherein: 1.1-Dewar jar, 1.2-Liquid nitrogen valve, 1.3-Vacuum insulated hose, 1.4-Cryogenic flow valve, 1.5-Cryogenic throttle valve, 1.6-Cryogenic hose connector, 1.7-Liquid nitrogen nozzle control device, 1.8-Straight rod, 1.9-Nitrogen valve, 1.10-Gas delivery pipe, 2.1-Spindle, 2.2-Tool holder, 2.3-Tool, 2.4-Clamping device, 2.5-Workpiece, 3.1-Magnetic block, 3.2-First thermocouple, 3.3-Second thermocouple, 3.4-Cable, 3.5-Thermometer, 3.6-System processor.

[0022] Figure 5 —Flowchart of the cryogenic cooling system of this invention.

[0023] Figure 6 —Diagram of the cutting process of this invention. Detailed Implementation

[0024] like Figure 4 As shown, the liquid nitrogen nozzle control device 1.7 of the present invention can be applied to a liquid nitrogen cryogenic cooling temperature control machining system. The liquid nitrogen cryogenic cooling temperature control machining system includes a Dewar jar 1.1 and a machine tool spindle 2.1. The liquid nitrogen valve 1.2 of the Dewar jar 1.1 is connected to the inlet of the cryogenic flow valve 1.4 through a hose 1.3. The outlet of the cryogenic flow valve 1.4 is connected to the inlet of the cryogenic throttle valve 1.5. The outlet of the cryogenic throttle valve 1.5 is connected to the liquid nitrogen inlet of the liquid nitrogen nozzle control device 1.7. The liquid nitrogen nozzle of the liquid nitrogen nozzle control device 1.7 is provided with a straight rod 1.8, and the outer end of the straight rod 1.8 is placed outside the liquid nitrogen nozzle.

[0025] The straight rod 1.8 is not connected to the liquid nitrogen nozzle. The straight rod 1.8 is used to help align the axis of the liquid nitrogen nozzle with the tip of the tool 2.3. After alignment, the straight rod 1.8 is pulled out and removed.

[0026] The straight rod 1.8 can move freely in the nozzle hole. Once it touches the blade tip and confirms that the nozzle axis is aligned with the blade tip, it can be moved away, similar to the function of the blade block.

[0027] The lower end of the machine tool spindle 2.1 is connected to a tool holder 2.2, the lower end of the tool holder 2.2 is connected to a cutting tool 2.3, and a workpiece 2.5 is placed below the cutting tool 2.3. The workpiece 2.5 is set on the worktable by a fixture 2.4.

[0028] The nitrogen valve 1.9 of the Dewar 1.1 is connected to one end of the gas delivery pipe 1.10 (a vacuum insulated hose can be used, which uses the low-temperature nitrogen output from the Dewar 1.1 to isolate air and prevent frost). The other end of the gas delivery pipe 1.10 is placed at the outer end of the straight rod 1.8.

[0029] It also includes a first thermocouple 3.2 for detecting the temperature of the outer end of the straight rod 1.8 and a second thermocouple 3.3 for detecting the temperature of the liquid nitrogen nozzle of the liquid nitrogen nozzle control device 1.7; the detection signal output port of the second thermocouple 3.3 is connected to the detection signal input port of the thermometer 3.5 (which can be a model SDK TKDT 10 thermometer) via cable 3.4, the detection signal output port of the first thermocouple 3.2 is connected to the detection signal input port of the thermometer 3.5, the detection signal output port of the thermometer 3.5 is connected to the detection signal input port of the system processor 3.6 (which can be a computer), and the control signal output port of the system processor 3.6 is connected to the control signal input port of the liquid nitrogen nozzle control device 1.7.

[0030] In this invention, liquid nitrogen is transported from the Dewar canister to the liquid nitrogen nozzle and finally sprayed onto the contact point between the blade tip and the workpiece to achieve the purpose of cryogenic cooling.

[0031] The liquid nitrogen cryogenic cooling temperature control machining system of this invention adopts the external liquid nitrogen spray cooling method. The distance between the liquid nitrogen nozzle and the tool tip is changed by the liquid nitrogen spray pipe adjustment device to achieve precise and rapid control of the low temperature. At the same time, the low temperature nitrogen gas output from the Dewar canister is blown towards the workpiece-tool cutting area to achieve the function of isolating air and preventing frost formation, thus preventing frost formation due to low temperature medium cooling.

[0032] This invention uses a liquid nitrogen nozzle control device to change the distance between the liquid nitrogen nozzle and the cutting tool tip, thereby controlling the liquid nitrogen cooling temperature at the cutting contact point of the tool / workpiece. This allows for temperature control, improving the precision of cryogenic cooling cutting of difficult-to-machine materials, enhancing the cutting integrity of the machining area, enabling large cutting parameters and flexible output cryogenic cutting of difficult-to-machine structural workpieces, and improving the mechanical machinability of such materials. It is highly practical.

[0033] Commonly used and difficult-to-machine materials in aerospace can be cut into the required shape. Then, the surface of the workpiece 2.5 is cleaned with deionized water and dried. Finally, the workpiece 2.5 is positioned and clamped on the CNC machine tool table according to the positioning principle.

[0034] The hose 1.3 is a vacuum-insulated hose.

[0035] The outlet of the cryogenic throttle valve 1.5 is connected to the liquid nitrogen inlet of the liquid nitrogen nozzle control device via a cryogenic hose connector 1.6. Practical verification has shown that, based on the requirements of the liquid nitrogen cooling process, the portion of the cryogenic hose connected to the liquid nitrogen straight pipe 4.9 needs frequent disassembly. Furthermore, to prevent sealing failure and liquid nitrogen leakage caused by frequent loosening of the flange connecting the cryogenic throttle valve 1.5 and the cryogenic hose, the portion of the cryogenic hose connected to the liquid nitrogen straight pipe 4.9 is not directly connected to the cryogenic throttle valve 1.5, but rather connected via a cryogenic hose connector 1.6.

[0036] The liquid nitrogen nozzle control device 1.7 includes a magnetic block 4.1, which is connected to the upper end of the upper connecting rod 4.2. The lower end of the upper connecting rod 4.2 is connected to a linear motor 4.5. The movable end of the linear motor 4.5 is connected to a movable block 4.6, which is connected to the upper end of a standard ruler 4.11 and the upper end of a lower connecting rod 4.8. A liquid nitrogen straight tube 4.9 is installed on the lower connecting rod 4.8, and a protractor 4.14 is installed on the standard ruler 4.11.

[0037] The magnetic block 4.1 is connected to the upper end of the upper connecting rod 4.2 by the upper fastening screw 4.3, and the lower end of the upper connecting rod 4.2 is connected to the linear motor 4.5 by the lower fastening screw 4.4.

[0038] The movable block 4.6 is connected to the upper end of the standard ruler 4.11 by the standard ruler fastening screw 4.12.

[0039] The movable block 4.6 is connected to the upper end of the lower connecting rod 4.8 by bolt group 4.7.

[0040] The lower connecting rod 4.8 is provided with a mounting hole, through which the liquid nitrogen straight tube 4.9 passes. Threaded holes are provided around the mounting hole, and the front end of the liquid nitrogen straight tube fastening screw 4.10 is screwed through the threaded hole and abuts against the outer wall of the liquid nitrogen straight tube 4.9.

[0041] The lower connecting rod 4.8 includes a first connecting rod 5.2 and a second connecting rod 5.5. The first connecting rod 5.2 has a mounting hole and a fastening screw 4.10 at its lower end. The upper part of the first connecting rod 5.2 has a protrusion at its middle. The lower part of the second connecting rod 5.5 has a connecting groove corresponding to the protrusion at its middle. The connecting groove wall has a threaded hole. The front end of the fastening screw 5.4 of the first connecting rod is screwed through the threaded hole and abuts against the protrusion. The upper end of the second connecting rod 5.5 is connected to the movable block 4.6 through a bolt group 4.7. The upper part of the second connecting rod 5.5 is placed in the opening groove at the lower end of the movable block 4.6.

[0042] The upper connecting rod 4.2 has a strip-shaped opening 4.15 along its length. The front end of the upper fastening screw 4.3 passes through the strip-shaped opening 4.15 and is screwed into the threaded hole on the magnetic block 4.1. The width of the head of the upper fastening screw 4.3 is greater than the width of the strip-shaped opening 4.15.

[0043] The specific operation steps of the liquid nitrogen external cooling milling process using the machining system of this invention are as follows:

[0044] Step 1) as Figure 4 As shown, the tool 2.3 is installed on the tool holder 2.2, and the tool holder 2.2 is installed in the tapered hole of the machine tool spindle 2.1. The tool holder 2.2 is clamped and fixed by using the tool clamping cylinder in the spindle box to pull the pull stud at the tail end of the tool holder 2.2.

[0045] Step 2) Clamp workpiece 2.5 onto the CNC machine tool worktable using fixture 2.4;

[0046] Step 3) Install the upper connecting rod 4.2 onto the magnetic block 4.1, and fix it by rotating the upper fastening screw 4.3. Fix the upper connecting rod 4.2 onto the linear motor 4.5 using the lower fastening screw 4.4. Fix the movable block 4.6 to the movable end of the linear motor 4.5. Install the lower connecting rod 4.8 into the open slot at the other end of the movable block 4.6 using the bolt set 4.7, forming a universal joint structure. Loosen the bolt set 4.7 to allow the lower connecting rod 4.8 to rotate around the axis of the bolt set 4.7. Tighten the nut of the bolt set 4.7 to fix the lower connecting rod 4.8. The liquid nitrogen straight tube 4.9 passes through the mounting hole of the lower connecting rod 4.8 and is fixed with the liquid nitrogen straight tube fastening screw 4.10. Fix the standard ruler 4.11 onto the movable block 4.6 using the standard ruler fastening screw 4.12. Finally, install the protractor 4.14 into the slot of the standard ruler 4.11 using the protractor fastening screw 4.13. Figure 3 As shown in the angle ruler structure, loosen the protractor fastening screw 4.13 and adjust the crossbar of the protractor 4.14 (i.e., Figure 3 When the horizontal bar is aligned with the axial direction of the liquid nitrogen straight tube 4.9 (using the thick solid line in the middle diagonal), the angle indicated by the protractor 4.14 is the liquid nitrogen jet angle (i.e., the angle indicated by the protractor 4.14). Figure 3 (Angle shown in the circle).

[0047] Step 4) Figure 1 After determining the liquid nitrogen jet angle in the liquid nitrogen straight tube 4.9 according to process requirements, the liquid nitrogen nozzle control device 1.7 is adjusted. First, loosen the standard ruler fastening screw 4.12 and adjust the standard ruler 4.11 so that its long rod is horizontal with the side of the magnetic block 4.1. Then, loosen the nut of the bolt group 4.7 so that the liquid nitrogen straight tube 4.9 can rotate around the axis of the bolt group 4.7, and use the protractor 4.14 on the standard ruler 4.11 to determine that the angle between the axis of the liquid nitrogen straight tube 4.9 and the standard ruler 4.11 is equal to the preset spray angle. Next, loosen the upper fastening screw 4.3 and rotate the upper connecting rod 4.2 so that the angle between the upper connecting rod 4.2 and the side of the magnetic block 4.1 is also equal to the liquid nitrogen set angle. Finally, attach the entire liquid nitrogen nozzle control device 1.7 to the side of the machine tool spindle box using the magnetic block 4.1.

[0048] Step 5) Insert the straight rod 1.8 into the nozzle hole of the liquid nitrogen straight tube 4.9, loosen the upper fastening screw 4.3, adjust the position of the upper fastening screw 4.3 at the strip-shaped opening 4.15, and then adjust the angle and distance of the entire component below the linear motor 4.5 with the upper fastening screw 4.3 as the axis; at the same time, adjust the universal joint angle of the lower connecting rod 4.8 so that the axis of the straight rod 1.8 and the cutter 2.3 are on the same straight line, that is, the nozzle is aligned with the cutter tip. Finally, loosen the liquid nitrogen straight tube fastening screw 4.10 and adjust the distance between the liquid nitrogen straight tube 4.9 and the cutter tip to the set distance;

[0049] Step 6) Figure 2 The liquid nitrogen straight tube 4.9, inserted into the mounting hole of the first connecting rod 5.2, is fixed using the liquid nitrogen straight tube fastening screw 4.10. The second connecting rod 5.5 is extended into the open slot of the movable block 4.6 and fixed using the bolt group 4.7 and nut combination. Finally, the upper protrusion (which can be a cylindrical protrusion) of the first connecting rod 5.2 is extended into the lower connecting slot (which can be an open slot) of the second connecting rod 5.5 and fixed using the first connecting rod fastening screw 5.4. Loosening the first connecting rod fastening screw 5.4 and the bolt group 4.7 allows the first connecting rod 5.2 and the second connecting rod 5.5 to rotate around the upper cylindrical axis of the first connecting rod 5.2 and the axis of the bolt group 4.7, respectively, thus realizing the flexible rotational movement of the liquid nitrogen straight tube 4.9.

[0050] Step 7) Unscrew the liquid nitrogen valve 1.2 on the liquid nitrogen Dewar canister 1.1 to allow liquid nitrogen to flow into the vacuum insulation hose 1.3, and then sequentially through the cryogenic flow valve 1.4, cryogenic throttle valve 1.5, and cryogenic hose connector 1.6 connected to it into the liquid nitrogen straight pipe 4.9, and finally spray out from the end nozzle;

[0051] Step 8) Use magnetic block 3.1 to fix the first thermocouple 3.2 to the spindle box. The front end of the first thermocouple 3.2 is placed near the tip of the cutting tool 2.3 to measure the temperature at the tip of the liquid nitrogen injection. The second thermocouple 3.3 (the head of the second thermocouple 3.3 can be glued to the nozzle of the liquid nitrogen straight pipe 4.9 with waterproof tape) is placed at the nozzle of the liquid nitrogen straight pipe 4.9 to measure the liquid nitrogen outlet temperature. The two thermocouples are connected to the thermometer 3.5 through cable 3.4. The thermometer 3.5 transmits the measured temperature signal to the system processor 3.6.

[0052] Step 9) The liquid nitrogen temperature T2 collected by the first thermocouple 3.2 and sprayed onto the cutting tool 2.3 is transmitted to the temperature measuring instrument 3.5 via the data transmission cable 3.4, and then the data is transmitted to the system processor 3.6. The system processor 3.6 sets up a database corresponding to the liquid nitrogen flow rate, temperature, and distance between the nozzle and the cutting tool tip. The flow rate ranges from 1L / h to 35L / h, the temperature range is -190℃ to 0℃, and the distance between the nozzle and the cutting tool tip is 10mm to 200mm. Figure 5 The system sets a reference temperature T1 for the liquid nitrogen nozzle by querying the database, and simultaneously measures the temperature T2 at the tip of the milling cutter 2.3, and feeds this information back to the system processor 3.6. The nozzle temperature error is determined by the formula ΔT = T1 - T2. When |ΔT| ≤ 5℃, the processor controls the linear motor 4.5 to change the distance between the liquid nitrogen straight pipe 4.9 nozzle and the cutter tip. If ΔT ≥ 5℃, the distance is reduced; if ΔT ≤ -5℃, the distance is increased. After 5 seconds, the cutter tip temperature T2 is measured again. Each measurement distance is adjusted by 5mm, and the above adjustment process is repeated until |ΔT| ≤ 5℃.

[0053] Step 10) Feed rate setting

[0054] like Figure 6 As shown, the diameter D of the liquid nitrogen external spray cooling area n , represented as:

[0055] D n =2L n (cosα n tan(α n +β n / 2)-sinα n (1)

[0056] In the formula: L n α is the distance from the nozzle to the workpiece at the 2.5 cutting point. n Jet center angle (o), β n Jet nozzle jet angle (°);

[0057] The time during which the machining area is subjected to liquid nitrogen impact is the number of feeds (NI) of the tool along the feed distance within the radius of the cooling zone. LN2 for:

[0058]

[0059] In the formula: f z It is the feed per tooth (mm / z).

[0060] In actual machining, the effective cooling time is the feed time t of the tool along the radius of the circle formed by the cooling zone. f for:

[0061]

[0062] In the formula: z is the number of teeth on the cutting tool, and n is the spindle speed of the machine tool (r / min).

[0063] The feed time must not exceed the cooling time t of the liquid nitrogen. c And the depth of cut must be less than the depth of cut during the cooling time t. c The internal cooling depth.

[0064] Step 11) Start the machine tool. The machine tool spindle 2.1 rotates, driving the tool 2.3 to rotate. Prepare for tool setting at a low speed of the machine tool spindle 2.1. Then, gradually adjust the speed of the machine tool spindle 2.1 to the high-speed rotation level and set machining parameters such as feed rate and depth of cut.

[0065] Step 12) Complete different milling processes by changing the operation and process parameters in steps 1), 2), 5), 6), 9), and 10).

[0066] Step 13) For liquid nitrogen temperature control processes requiring variable temperatures during machining, it is necessary to first establish a mathematical function relationship between the spatial position change of the machining surface and temperature. Then, based on the database of required cooling temperatures for various parts of the workpiece (2.5), a mathematical function relationship between the tool tip / nozzle distance and the position change of the machining surface is fitted.

[0067] P Ln =f(x,y,z,T) (x,y,z) (4).

[0068] P Ln The distance between the tool tip and the nozzle is (mm), x, y, z are the rectangular coordinates of the machined surface position, and T is the distance between the tool tip and the nozzle. (x,y,z) The required cooling temperature (°C) is given at the position corresponding to the x, y, z coordinates.

[0069] To prevent machining errors caused by the evolution of the shape properties of the 2.5 alloy workpiece due to low temperature, milling errors can be reduced in CNC machining through machining error compensation strategies based on machining process parameters.

[0070] Because this invention can change the distance between the liquid nitrogen nozzle and the cutting tool tip in real time (by receiving temperature feedback through the system processor 3.6 and controlling the linear motor 4.5), it solves the problems of high cutting temperature and insufficient cooling effect of liquid nitrogen internal spray cooling in conventional cooling milling, which leads to low cutting removal rate and the need for controllable variable temperature and low temperature output in cutting. It also eliminates the defect of reduced performance of the processed sample due to burrs, ensures the machining accuracy of machine tools in milling difficult-to-machine materials, and improves the machining range of high-speed CNC machine tools.

[0071] It is understood that the above specific description of the present invention is only for illustrating the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effect; as long as the use needs are met, they are all within the protection scope of the present invention.

Claims

1. A liquid nitrogen lance regulation device comprising a magnetic solid (4.1), characterized in that The magnetic solid block (4.1) is connected with the upper end of the upper connecting rod (4.2), the lower end of the upper connecting rod (4.2) is connected with the linear motor (4.5), the movable block (4.6) is connected with the upper end of the standard ruler (4.11), the movable block (4.6) is connected with the upper end of the lower connecting rod (4.8), the liquid nitrogen straight pipe (4.9) is arranged on the upper connecting rod (4.8), and the protractor (4.14) is arranged on the standard ruler (4.11); The magnetic solid block (4.1) is connected with the upper end of the upper connecting rod (4.2) through the upper fastening screw (4.3), and the lower end of the upper connecting rod (4.2) is connected with the linear motor (4.5) through the lower fastening screw (4.4); The lower connecting rod (4.8) is provided with a mounting hole, the liquid nitrogen straight pipe (4.9) passes through the mounting hole, the mounting hole is provided with a threaded hole around the mounting hole, the front end of the liquid nitrogen straight pipe fastening screw (4.10) is abutted with the outer wall of the liquid nitrogen straight pipe (4.9) through the threaded hole, and then the liquid nitrogen straight pipe (4.9) is fixed; The lower connecting rod (4.8) comprises a first connecting rod (5.2) and a second connecting rod (5.5), the first connecting rod (5.2) is provided with a mounting hole, the lower end of the first connecting rod (5.2) is provided with a fastening screw (4.10), the upper end of the first connecting rod (5.2) is provided with a protrusion in the middle, the second connecting rod (5.5) is provided with a connecting groove in the middle of the lower end, the connecting groove is provided with a threaded hole on the wall, the front end of the first connecting rod fastening screw (5.4) is abutted with the protrusion through the threaded hole, the upper end of the second connecting rod (5.5) is connected with the movable block (4.6) through the bolt group (4.7), and the second connecting rod (5.5) is arranged in the open slot at the lower end of the movable block (4.6); The upper connecting rod (4.2) is provided with a strip-shaped opening (4.15) along the length direction of the upper connecting rod (4.2), the front end of the upper fastening screw (4.3) passes through the strip-shaped opening (4.15) and is screwed into the threaded hole in the magnetic solid block (4.1), and the head end width of the upper fastening screw (4.3) is greater than the width of the strip-shaped opening (4.15); The liquid nitrogen spray pipe regulating device is applied to a liquid nitrogen ultra-low temperature cooling temperature control processing system, the liquid nitrogen ultra-low temperature cooling temperature control processing system comprises a Dewar flask (1.1) and a machine tool spindle (2.1), the liquid nitrogen valve (1.2) of the Dewar flask (1.1) is connected with the inlet of the low-temperature flow valve (1.4) through the hose (1.3), the outlet of the low-temperature flow valve (1.4) is connected with the inlet of the low-temperature throttle valve (1.5), the outlet of the low-temperature throttle valve (1.5) is connected with the liquid nitrogen inlet of the liquid nitrogen spray pipe regulating device, and the liquid nitrogen nozzle of the liquid nitrogen spray pipe regulating device is provided with a straight rod (1.8), and the outer end of the straight rod (1.8) is arranged outside the liquid nitrogen nozzle. When the liquid nitrogen nozzle control device is used, the magnetic solid block (4.1) is installed with the upper connecting rod (4.2), the upper connecting rod (4.2) is fixed on the linear motor (4.5), the movable end of the linear motor (4.5) is fixed with the movable block (4.6), the lower connecting rod (4.8) is installed on the other end of the movable block (4.6), and the structure is a universal joint; the lower connecting rod (4.8) is rotatable and fixed, the standard ruler (4.11) is fixed on the movable block (4.6), and finally the protractor (4.14) is installed on the standard ruler (4.11); adjust the crossbar of the protractor (4.14), when the crossbar is axially aligned with the liquid nitrogen straight pipe (4.9), the angle indicated by the protractor (4.14) is the liquid nitrogen jet angle; After the liquid nitrogen jet angle in the liquid nitrogen straight pipe (4.9) is determined, the liquid nitrogen nozzle control device is controlled; adjust the standard ruler (4.11) so that the long rod direction is horizontal to the side surface of the magnetic solid block (4.1); rotate the liquid nitrogen straight pipe (4.9) and use the protractor (4.14) on the standard ruler (4.11) to determine that the angle between the axis of the liquid nitrogen straight pipe (4.9) and the standard ruler (4.11) is equal to the preset jet angle; then, rotate the upper connecting rod (4.2) so that the angle between the upper connecting rod (4.2) and the side surface of the magnetic solid block (4.1) is also equal to the liquid nitrogen set angle; finally, the liquid nitrogen nozzle control device is adsorbed on the side surface of the machine tool spindle box by the magnetic solid block (4.1); The straight rod (1.8) is not connected with the liquid nitrogen nozzle, and the straight rod (1.8) is used to assist the alignment of the axis direction of the liquid nitrogen nozzle with the tool tip; after alignment, the straight rod (1.8) is pulled out and removed; The straight rod (1.8) is freely movable in the nozzle hole, and after the nozzle axis is determined to be aligned with the tool tip, the straight rod (1.8) is removed; The lower end of the machine tool spindle (2.1) is connected with the tool holder (2.2), the lower end of the tool holder (2.2) is connected with the tool (2.3), and the tool (2.3) is placed below the workpiece (2.5); the workpiece (2.5) is arranged on the workbench through the clamp (2.4); The nitrogen valve (1.9) of the Dewar flask (1.1) is connected with one end of the gas guide pipe (1.10), and the other end of the gas guide pipe (1.10) is arranged at the outer end of the straight rod (1.8); It also includes a first thermocouple (3.2) for detecting the temperature of the outer end of the straight rod (1.8) and a second thermocouple (3.3) for detecting the temperature of the liquid nitrogen nozzle of the liquid nitrogen nozzle control device; the detection signal output port of the second thermocouple (3.3) is connected with the detection signal input port of the temperature measuring instrument (3.5) through the cable (3.4), the detection signal output port of the first thermocouple (3.2) is connected with the detection signal input port of the temperature measuring instrument (3.5), the detection signal output port of the temperature measuring instrument (3.5) is connected with the detection signal input port of the system processor (3.6), and the control signal output port of the system processor (3.6) is connected with the control signal input port of the liquid nitrogen nozzle control device; The temperature T2 of the liquid nitrogen sprayed to the tool tip of the tool (2.3) is collected by the first thermocouple (3.2) and transmitted to the temperature measuring instrument (3.5) through the data transmission cable (3.4), and then the data is transmitted to the system processor (3.6); The system processor (3.6) is provided with a database corresponding to the liquid nitrogen flow, temperature and nozzle-to-tool tip distance, the flow range is from 1L / h to 35L / h, the temperature range is from -190℃ to 0℃, and the nozzle-to-tool tip distance is from 10mm to 200mm; by querying the database to set the liquid nitrogen nozzle temperature reference value T1, the temperature T2 of the tool tip of the milling tool (2.3) is measured at the same time, and the feedback is given to the system processor (3.6), and the nozzle temperature error is judged by the formula ΔT=T1-T2, when |ΔT|≤5℃, the linear motor (4.5) is controlled by the processor to change the nozzle-to-tool tip distance of the liquid nitrogen straight pipe (4.9); if ΔT≥5℃, the distance is reduced, if ΔT≤-5℃, the distance is increased, after 5 seconds, the tool tip temperature T2 of the tool (2.3) is measured again, the adjustment change of each measurement distance is 5mm, and the above adjustment process is repeated until |ΔT|≤5℃; The feed amount setting The diameter D of the liquid nitrogen outer spray cooling zone n is expressed as: D n = 2L n (cos α n t an (α n + β n / 2) - sin α n ) In the formula: L n Distance from the cutting point of the nozzle to the workpiece (2.5) α n Jet center angle, β n Jet angle of the jet port The time of the machining zone subjected to the liquid nitrogen impact is the number of feeds N1 of the tool over the feed distance on the radius of the cooling zone LN2 is: wherein: f is the feed per tooth (mm / z); and z is the feed per tooth (mm / z); and In actual machining, the effective cooling time is the feeding time t of the tool in the circular radius distance formed by the cooling area f is: In the formula, z is the number of tool teeth, and n is the spindle speed (r / min) The feeding time cannot exceed the cooling time t of the liquid nitrogen c , and the cutting depth is to be less than the cooling depth within the cooling time t c . The machine tool is started, the machine tool spindle (2.1) rotates to drive the tool (2.3) to rotate, the tool setting preparation work is done under the low speed of the machine tool spindle (2.1), then the speed of the machine tool spindle (2.1) is adjusted to the high speed rotation level, and the machining parameters such as the feed amount and the back engagement amount are set; For the liquid nitrogen temperature control process with variable temperature in machining, it is necessary to first establish the mathematical function relationship between the spatial position change of the machined surface and the temperature, and then based on the cooling temperature database required by each part of the workpiece (2.5), the mathematical function relationship between the tool tip / nozzle distance and the machined surface position change is fitted P Ln = f(x, y, z, T (x,y,z) ); P Ln is the tool tip / nozzle distance (mm), x, y, z are the cartesian coordinates of the machining surface position, T (x,y,z) is the required cooling temperature at the position corresponding to the x, y, z coordinates.

2. The liquid nitrogen nozzle regulation device of claim 1, wherein The movable block (4.6) is connected with the upper end of the standard ruler (4.11) through the standard ruler fastening screw (4.12).

3. The liquid nitrogen nozzle regulation device of claim 1, wherein The movable block (4.6) is connected with the upper end of the lower connecting rod (4.8) through the bolt group (4.7).

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