Main shaft low-temperature stable braking numerical control machine tool

Abstract

The invention discloses a spindle low-temperature stable braking numerical control machine tool, belongs to the technical field of machine tools, and solves the problems that the temperature of a spindle is indirectly estimated through the temperature, vibration and displacement of front and rear bearings of the spindle in a conventional software compensation method at present, the temperature of the spindle cannot be directly measured, thermal error compensation is inaccurate, and finally the machining precision of the machine tool is affected. Comprising a lathe, a shell fixedly connected to the lathe, a lower axle box fixedly connected to the lathe and located in the shell, and an upper axle box detachably connected to the lower axle box. When the device works, a metal piece is clamped on the three-jaw chuck, heat generated by cutting is transmitted to one end of the main shaft, and heat generated by friction between a brake disc and a brake drum is transmitted to the other end of the main shaft. As the temperature of the main shaft and the brake disc is difficult to directly measure, the heat at two ends of the main shaft is speculated through the water temperature in the movable cavity and the brake drum temperature for thermal error compensation. Meanwhile, water in the movable cavity cools the spindle, thermal expansion deformation is reduced, compensation difficulty is lowered, and machining precision is improved.

Description

Technical Field

[0001] The invention relates to the technical field of machine tools, and in particular to a spindle low-temperature brake-stabilizing numerically controlled machine tool. Background Art

[0002] CNC machine tools are highly automated and intelligent advanced manufacturing equipment, which are widely used in the field of mechanical processing. It controls the movement and processing operations of the machine tool through the computer numerical control system (CNC), and can achieve high-precision and high-efficiency parts processing. The core of CNC machine tools is the CNC system, which accurately controls the relative movement of the tool and the workpiece according to the pre-input program instructions to complete complex processing tasks. Compared with traditional machine tools, CNC machine tools have significant advantages: first, it can realize multi-axis linkage processing and can process parts with complex shapes, such as aerospace parts, automobile engine crankshafts, etc.; second, the processing accuracy of CNC machine tools is extremely high, usually up to the micron level, which is suitable for mass production of high-precision parts; in addition, CNC machine tools have a high degree of automation, which reduces manual intervention and improves production efficiency and product quality stability. There are many types of CNC machine tools, including CNC lathes, CNC milling machines, machining centers, CNC grinders, etc., which are suitable for different processing needs. With the continuous advancement of technology, CNC machine tools are developing towards higher precision, higher efficiency, intelligence and networking, becoming an indispensable core equipment in modern manufacturing and promoting the automation and intelligentization of industrial production.

[0003] When current CNC machine tools perform milling and turning compound operations, the machine tool spindle needs to be coordinated with a braking system to control the speed and quickly stop the machine tool spindle. The spindle braking system generates braking force through electromagnetic or mechanical means, quickly converting the inertial kinetic energy of the spindle into thermal energy to achieve rapid shutdown. This system not only improves the processing efficiency of the machine tool, but also effectively reduces the processing errors and safety hazards caused by the inertial rotation of the spindle.

[0004] Most of the existing brake systems are connected to the brake system of the car wheel hub, and brakes are performed by brake discs and brake pads. Specifically, the two perform local friction. During the actual braking process, transmission instability is prone to occur, which affects the stability of the main shaft rotation. Therefore, a brake drum structure is currently used for braking to ensure its braking stability.

[0005] For example, a spindle damping, anti-shake and braking mechanism for a turning-milling compound machine tool with application number CN202022733049.1 has the following technical points: it includes a spindle box, a spindle mechanism and a mechanical locking mechanism are installed on the spindle box, a brake disc is installed on the spindle mechanism, the mechanical locking mechanism includes a brake seat and a brake, the mechanical locking mechanism is connected to a pneumatic booster mechanism, the pneumatic booster mechanism includes an air-to-liquid booster cylinder, the air-to-liquid booster cylinder is connected to the brake through a hydraulic oil pipe, the air-to-liquid booster cylinder is connected to a three-position, five-way, double-control solenoid reversing valve one through air pipe three, the three-position, five-way, double-control solenoid reversing valve one is connected to a pressure reducing and regulating valve through air pipe two, the pressure reducing and regulating valve is connected to a pneumatic two-joint through air pipe one, the pneumatic two-joint is connected to a three-position, five-way, double-control solenoid reversing valve two through air pipe four, and the three-position, five-way, double-control solenoid reversing valve two is connected to the air-to-liquid booster cylinder through air pipe five.

[0006] It is precisely because the spindle brake system as mentioned above converts the inertial kinetic energy of the spindle into heat energy, the heat will be transferred to the spindle. Although the braking stability is increased, the heat generated will also increase. At the same time, the spindle is not only affected by the heat of the brake system, but also receives a large amount of heat generated when cutting metal parts. The transfer of these heat will cause the spindle to expand and deform due to heat, which will cause it to shake and vibrate.

[0007] In order to solve this problem, the spindle of the machine tool often uses thermal error compensation technology, and this thermal error compensation method mainly includes two categories: hardware compensation and software compensation. Hardware compensation requires the use of additional thermal control equipment, such as a cooling system, specifically a water jacket set on the outer ring of the spindle and installed in the spindle box. The water jacket is connected to the chiller to circulate coolant and directly adjust the temperature of the machine tool. Software compensation is achieved by embedding error compensation instructions in the CNC program. Among them, software compensation is divided into direct method and indirect method. The direct method requires clear knowledge of the specific value of the thermal error and relies on high-precision sensors for measurement. At the same time, since the spindle always keeps rotating, it is difficult to detect its temperature. The indirect method constructs a thermal model of the machine tool and performs error compensation based on the model prediction results. The low-cost thermal error compensation method based on the indirect method does not need to directly measure the thermal error, but collects temperature data and combines calculations to establish a temperature-thermal extension prediction curve to achieve error compensation. This method uses host computer data acquisition software, temperature sensors and temperature acquisition cards to mainly monitor the temperature of the front and rear bearings of the spindle, and real-time feedback and control the machine tool for compensation to ensure the stability of the spindle offset, thereby ensuring the machining accuracy of the machine tool.

[0008] Therefore, the current conventional means are to complete software compensation through indirect methods, and use the temperature of the front and rear bearings of the spindle as the temperature reference of the spindle, and combine the vibration and displacement of the spindle to complete the thermal error compensation. However, this method is not a direct temperature detection of the spindle, which leads to inaccurate heat receiving conditions on the spindle. Ultimately, even if thermal error compensation is performed, the output result will still become inaccurate, resulting in poor precision of the final machine tool product.

[0009] Therefore, a spindle low temperature brake stabilization CNC machine tool is proposed to solve or alleviate the above problems. Summary of the invention

[0010] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a spindle low temperature brake stabilization CNC machine tool.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] A spindle low-temperature stable brake CNC machine tool, comprising a lathe, a shell fixedly connected to the lathe, a lower axle box fixedly connected to the lathe and located in the shell, an upper axle box detachably connected to the lower axle box, a spindle rotatably connected between the upper axle box and the lower axis through two bearings and having two ends passing through, and a driving motor fixedly connected to the lathe, one end of the spindle is fixedly connected to a brake disc, the outer side of the spindle is sleeved with a brake drum that can be reset and moved along its length direction, one end of the spindle connected to the brake disc is transmission-connected to the driving motor, and the other end of the spindle passes through the shell back A three-jaw chuck is fixedly connected, and the outer ring of the main shaft is fixedly connected with four groups of fixed water storage covers which are arranged at intervals and are located between two bearings and are in an annular shape. A rotatable dynamic water storage cover is sleeved between adjacent fixed water storage covers, and an active cavity is formed between the adjacent fixed water storage covers, the dynamic water storage cover, and the outer ring of the main shaft. Water can be entered and exited from the active cavity, and an exhaust gap is provided between the dynamic water storage cover and the fixed water storage cover. The outer ring of the dynamic water storage cover is provided with a ventilation arc channel therein, and the inner wall of the ventilation arc channel is provided with an air inlet hole connected to the exhaust gap, and compressed air is continuously introduced into the ventilation arc channel.

[0013] Preferably, a driving wheel is fixedly connected to the rotor shaft of the driving motor, and a driven wheel is fixedly connected to the end of the main shaft away from the three-jaw chuck, and the driving wheel and the driven wheel are connected by a transmission belt.

[0014] Preferably, a horizontally arranged hydraulic rod is fixedly connected to the inner wall of the shell, a connecting groove and a plurality of detection through holes are provided on the side of the brake drum away from the brake disc, a mounting tube connected to the detection through holes is fixedly connected to the side of the brake drum away from the brake disc, a first temperature sensor is fixedly connected in the mounting tube, the piston rod of the hydraulic rod is fixedly connected to a U-shaped connecting frame, and the connecting frame is fixedly connected to the connecting groove by bolts.

[0015] Preferably, the dynamic water storage cover comprises an annular sleeve, a double-ring cover fixedly connected to the inner and outer circles on both sides of the annular sleeve, a shielding part fixedly connected to the double-ring cover at one end away from the annular sleeve and arranged toward each other, and a porous structure ring part fixedly connected in the shielding part and having a U-shaped cross-section, the top and bottom of the outer ring of the annular sleeve are respectively provided with a water inlet through hole and a water outlet through hole connected to the active cavity, the number of the ventilation arc channels is two, the two ventilation arc channels are symmetrically arranged on both sides of the water outlet through hole, and the lower end of the ventilation arc channel is provided with the outer ring of the annular sleeve, the upper end of the ventilation arc channel extends into the annular sleeve, and the top of the outer ring of the annular sleeve is provided with an exhaust hole connected to the active cavity. The annular sleeve is fixedly connected with a pressure relief valve communicated with the exhaust hole, the annular sleeve is fixedly connected with a water inlet pipe joint communicated with the water inlet through hole, and a water outlet pipe joint communicated with the water outlet through hole, the annular sleeve is fixedly connected with an air inlet pipe joint communicated with the lower end of the ventilation arc, the air inlet pipe joint is connected with an air compressor through an air inlet pipe, the water inlet pipe joint is connected with a chiller through an water inlet pipe, the water outlet pipe joint is connected with a water outlet pipe, the water outlet pipe, the water inlet pipe and the air inlet pipe are all connected with an electromagnetic valve, the outer ring of the annular sleeve is provided with a mounting through hole communicated with the active cavity, a second temperature sensor is fixedly connected in the mounting through hole, and a probe of the second temperature sensor extends into the active cavity.

[0016] Preferably, the inner circles of the two shielding parts are provided with exhaust gaps spaced apart from the inner and outer circles of the fixed water storage cover, and the width of the exhaust gaps increases from bottom to top.

[0017] Preferably, the porous structure ring portion is made of porous ceramic material.

[0018] Preferably, it also includes a parameter acquisition module, a data processing module, a thermal error compensation module, and a control module. The parameter acquisition module is used to collect the thermal error displacement of the spindle and transmit it to the thermal error compensation module. The data processing module is used to calculate the heat at both ends of the spindle according to the brake drum temperature and the water temperature in the active cavity and feed it back to the thermal error compensation module. The thermal error compensation module compensates for the thermal elongation error and thermal drift error of the spindle according to the thermal error displacement of the spindle and the heat at both ends of the spindle. The control module controls the water change action in the active cavity according to the water temperature in the active cavity.

[0019] Preferably, the parameter acquisition module includes a displacement sensor, the data processing module and the parameter acquisition module both include a processor, the control module includes a microcontroller, and the microcontroller is coupled to each solenoid valve.

[0020] Preferably, the data processing module is used to calculate the heat at both ends of the spindle according to the brake drum temperature and the water temperature in the active cavity and feed it back to the thermal error compensation module, including the following steps:

[0021] Define the end of the spindle connected to the brake disc as the left end of the spindle, and the end of the spindle connected to the three-jaw chuck as the right end of the spindle. The three active cavities are defined from left to right as the first active cavity, the second active cavity, and the third active cavity. Define the heat source temperature T of the left end of the spindle corresponding to the first active cavity 左 , the temperature of the heat source connected to the right end of the spindle corresponding to the third active cavity is T 右 ;

[0022] Establish the cavity water temperature change equation, Among them, h i is the convective heat transfer coefficient, c 水 is the specific heat capacity of water, T i is the temperature of the water in the i-th active chamber, T p,i is the temperature of the spindle at the i-th active cavity, A i is the heat exchange area between the ith active cavity and the main shaft, m i The mass of water in the ith active cavity;

[0023] Establish the temperature variation equation of the spindle section Among them, k 主轴 is the thermal conductivity of the spindle material, c 主轴 is the specific heat capacity of the spindle material, m p,i is the mass of the spindle corresponding to the i-th active cavity, A 横截 is the cross-sectional area of ​​the main axis, T 邻左 and T 邻右 is the temperature of the spindle or heat source at the corresponding adjacent active cavity, L 邻左 and L 邻右 is the length of the main axis at the corresponding position of the adjacent active cavity;

[0024] The solution is obtained by combining the water temperature in the active cavity with the Euler method formula, and the Euler method formula includes

[0025] The goal is to minimize the error between the water temperature detection data and the model prediction value, and define the loss function as the mean square error between the measured temperature and the predicted temperature. The temperature T of the heat sources at both ends is iteratively corrected using the gradient descent optimization algorithm. 左 and T右 , until convergence, output heat source temperature T 左 and T 右 ;

[0026] The heat source temperature T 左 and T 右 Switch to left end heat and right end heat.

[0027] Preferably, the data processing module is used to calculate the heat at both ends of the main shaft according to the brake drum temperature and the water temperature in the active cavity and feed it back to the thermal error compensation module, and also includes the following steps:

[0028] Calculate the first heat Q absorbed by the brake pad pad =m pad ·c pad ΔT pad , m pad =ρ pad ·A contact ·h pad , where m pad is the mass of the brake drum, c pad is the specific heat capacity of the brake drum, ΔT pad is the average temperature rise of the brake drum, ρ pad is the density of the brake drum, A contact is the contact area between the brake drum and the brake disc, h pad is the thickness of the brake drum;

[0029] Based on the first heat Q pad Combined with the thermal resistance ratio of the brake drum and the brake disc, calculate the second heat absorbed by the brake disc Among them, the thermal resistance of the brake drum is The thermal resistance of the brake disc is h disc is the thickness of the brake disc, k pad and k disc are the thermal conductivities of the brake drum and brake disc, respectively;

[0030] The second heat Q disc_initial Converted to the temperature of the brake disc to calculate the difference ΔT from the main shaft disc ;

[0031] According to the thermal conductivity, contact area, thickness and the difference ΔT between the brake disc and the main axis disc , the third heat transferred from the brake disc to the spindle is calculated by the steady-state heat conduction model t is the heat transfer time;

[0032] Calculate the difference between the third heat and the left heat, which is defined as the left loss heat;

[0033] The left heat loss is adjusted by the ratio of the left end heat to the right end heat to obtain the right heat loss. The sum of the right heat loss and the right end heat is defined as the fourth heat from the three-jaw chuck to the spindle. The third heat and the fourth heat are output as the heat at both ends of the spindle to the thermal error compensation module.

[0034] The present invention has the following beneficial effects:

[0035] When the present invention is actually working, the metal part is clamped on the three-jaw chuck, and the metal part generates heat when being cut. The heat is transferred to one end of the spindle, and the brake disc and the brake drum also generate heat due to friction during the process of stably braking and decelerating the spindle, and the heat is transferred to the other end of the spindle. Since the spindle and the brake disc rotate, it is difficult to detect the temperature. Therefore, the heat at both ends of the spindle is inferred by the water temperature in the active cavity and the temperature of the brake drum. Not only can the heat at both ends of the spindle be obtained for subsequent thermal error compensation, but the spindle can also be cooled and heat exchanged by the water in the active cavity, thereby minimizing thermal expansion and deformation of the spindle, and realizing thermal error compensation through physical means. Finally, the machine tool spindle can more accurately obtain the heat of the heat sources at both ends of the spindle during operation, so as to provide a more accurate data basis for the thermal error compensation of the spindle, while reducing the degree of thermal deformation and alleviating the difficulty of thermal error compensation of the spindle, so that the final output result is more accurate, so as to ensure that the metal parts produced and processed by this machine tool are of high precision. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 It is a structural schematic diagram of the present invention;

[0038] Figure 2 It is a structural schematic diagram of the upper axle box, the lower axle box, the drive motor, and the main shaft in the present invention;

[0039] Figure 3 It is a structural schematic diagram of the main shaft, brake disc, fixed water storage cover, and dynamic water storage cover in the present invention;

[0040] Figure 4 The cross-sectional view of the main shaft, brake disc, fixed water storage cover, and dynamic water storage cover in the present invention Figure 1 ;

[0041] Figure 5 for Figure 4 The enlarged view of point A in the middle;

[0042] Figure 6 for Figure 5 The enlarged view of point B in the middle;

[0043] Figure 7 for Figure 4 Enlarged view of point C in the middle;

[0044] Figure 8 for Figure 7 The enlarged view of point D in the middle;

[0045] Fig. 9 The cross-sectional view of the main shaft, brake disc, fixed water storage cover, and dynamic water storage cover in the present invention Figure 2 .

[0046] 1. Lathe; 2. Shell; 3. Drive motor; 4. Lower axle box; 5. Upper axle box; 6. Driving wheel; 7. Transmission belt; 8. Driven wheel; 9. Spindle; 10. Three-jaw chuck; 11. Brake disc; 12. Brake drum; 13. Mounting pipe; 14. Connecting groove; 15. Fixed water storage cover; 16. Dynamic water storage cover; 17. Water inlet pipe joint; 1701. Water inlet through hole; 18. Water outlet pipe joint; 1801. Water outlet through hole; 19. Air inlet pipe joint; 1901. Ventilation arc; 1902. Air inlet hole; 20. Pressure relief valve; 2001. Exhaust hole; 21. Annular sleeve; 22. Double-ring cover; 23. Shielding part; 24. Multi-porous structure ring; 25. Exhaust gap. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0050] In the description of the present invention, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the invention is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0051] Furthermore, the terms “first”, “second”, “third”, etc. are merely used for distinguishing descriptions and are not to be understood as indicating or implying relative importance.

[0052] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] A spindle low temperature brake stabilization CNC machine tool, such as Figure 1 As shown, it includes a lathe 1, a shell 2 fixedly connected to the lathe 1, a lower axle box 4 fixedly connected to the lathe 1 and located in the shell 2, an upper axle box 5 detachably connected to the lower axle box 4, a main shaft 9 rotatably connected between the upper axle box 5 and the lower axis through two bearings and having two ends passing through, and a driving motor 3 fixedly connected to the lathe 1, one end of the main shaft 9 is fixedly connected to a brake disc 11, the outer side of the main shaft 9 is sleeved with a brake drum 12 which can be reset and moved along its length direction, one end of the main shaft 9 connected to the brake disc 11 is transmission-connected to the driving motor 3, and the other end of the main shaft 9 passes through the shell 2 and is fixedly connected to a three-jaw chuck 10. The outer ring of the main shaft 9 is fixedly connected with four groups of fixed water storage covers 15 which are arranged at intervals and are located between two bearings and are in an annular shape. A rotatable dynamic water storage cover 16 is sleeved between adjacent fixed water storage covers 15. An active cavity is formed between adjacent fixed water storage covers 15, the dynamic water storage cover 16, and the outer ring of the main shaft 9. Water can enter and exit the active cavity. There is an exhaust gap 25 between the dynamic water storage cover 16 and the fixed water storage cover 15. The outer ring of the dynamic water storage cover 16 is provided with a ventilation arc 1901 located therein. The inner wall of the ventilation arc 1901 is provided with an air inlet 1902 which is connected to the exhaust gap 25, and the ventilation arc 1901 continuously passes compressed air.

[0054] During the actual operation of the present invention, the metal part is firmly clamped on the three-jaw chuck 10. When the metal part is cut, heat is generated, and the heat is transferred to one end of the spindle 9 along the spindle 9. At the same time, the brake disc 11 and the brake drum 12 cooperate to complete the stable braking and deceleration of the spindle 9. In this process, the friction between the brake disc 11 and the brake drum 12 will also generate heat and transfer it to the other end of the spindle 9. Since the spindle 9 and the brake disc 11 are in a rotating state, it is very difficult to directly detect the temperature. Therefore, the present invention adopts an indirect detection method: by measuring the water temperature in the active cavity and the temperature of the brake drum 12, the heat distribution at both ends of the spindle 9 is inferred. This method can not only effectively obtain the heat information at both ends of the spindle 9, provide data support for subsequent thermal error compensation, but also cool down the spindle 9 through the water in the active cavity. Heat exchange. In this way, the spindle 9 can minimize thermal expansion deformation, thereby realizing thermal error compensation by physical means. In actual operation, the present invention enables the machine tool spindle 9 to more accurately obtain the heat of the heat sources at both ends of the spindle 9 during operation, providing a more accurate data basis for the thermal error compensation of the spindle 9. At the same time, by reducing the degree of thermal deformation of the spindle 9, the difficulty of thermal error compensation is reduced, making the final output result more accurate. Finally, through the thermal error compensation mechanism of the present invention, the machine tool can significantly improve the processing accuracy when producing and processing metal parts, ensuring that the processed metal parts meet high-precision requirements.

[0055] Preferably, if Figure 2 As shown, a driving wheel 6 is fixedly connected to the rotor shaft of the driving motor 3 , and a driven wheel 8 is fixedly connected to the end of the main shaft 9 away from the three-jaw chuck 10 . The driving wheel 6 and the driven wheel 8 are connected through a transmission belt 7 .

[0056] The driving wheel 6 of the drive motor 3 is connected to the driven wheel 8 of the main shaft 9 through the transmission belt 7. The belt drive has the characteristics of buffering and vibration reduction, which can effectively absorb the impact when the motor starts and stops or the load changes suddenly, and avoid the vibration transmission caused by the rigid connection. The material selection and tension adjustment mechanism of the transmission belt 7 ensure the smooth power transmission and reduce the slippage phenomenon, thereby improving the transmission efficiency. The belt drive allows the drive motor 3 and the main shaft 9 to be arranged in a staggered manner in space, which is convenient for the compact design of the overall structure of the machine tool, and at the same time reduces the influence of the motor vibration on the precision of the main shaft 9. In addition, the interval mechanical transmission of the drive motor 3, the driving wheel 6, the driven wheel 8, and the transmission belt 7 makes it difficult for the heat generated by the drive motor 3 during operation to be transferred to the main shaft 9, reducing the heat received by the main shaft 9, reducing the thermal expansion deformation of the main shaft 9, ensuring the precision of the main shaft 9 during rotation, and not prone to shaking and jittering, thereby ensuring the precision of the machine tool during processing and production.

[0057] Preferably, if Figure 2As shown, a horizontally arranged hydraulic rod is fixedly connected to the inner wall of the shell 2, a connecting groove 14 and a plurality of detection through holes are provided on the side of the brake drum 12 away from the brake disc 11, a mounting tube 13 connected to the detection through holes is fixedly connected to the side of the brake drum 12 away from the brake disc 11, a first temperature sensor is fixedly connected inside the mounting tube 13, and a piston rod of the hydraulic rod is fixedly connected to a U-shaped connecting frame, which is fixedly connected to the connecting groove 14 by bolts.

[0058] A horizontal hydraulic rod is arranged on the inner wall of the housing 2, and is fixed to the connection groove 14 of the brake drum 12 through a U-shaped connecting frame. The hydraulic system can accurately control the axial displacement of the brake drum 12, realize the dynamic adjustment of the contact pressure between the brake disc 11 and the brake drum 12, ensure the smooth braking process and controllable braking force, and provide a detection through hole on the brake drum 12. A first temperature sensor is arranged in the mounting tube 13 to directly measure the temperature rise of the brake drum 12. The heat generated during the braking process can be evaluated in real time through the temperature data, and key input parameters are provided for the thermal error compensation module. The connecting frame is connected to the brake drum 12 by bolts, which is convenient for disassembly, maintenance or replacement of the brake assembly, and improves the maintainability of the system. In addition, during the braking process of the brake drum 12 and the brake disc 11, unlike the contact friction between the brake pad and the brake disc 11, the local friction is converted into the overall friction, ensuring that the brake disc 11 is more stable during braking, and it is not easy to cause the spindle 9 to shake and tremble, so as to avoid affecting the accuracy of the metal parts clamped on the three-jaw chuck 10 during processing.

[0059] Preferably, if Figures 3 to 9As shown, the dynamic water storage cover 16 includes an annular sleeve 21, a double-ring cover portion 22 fixedly connected to the inner and outer circles on both sides of the annular sleeve 21, a shielding portion 23 fixedly connected to the double-ring cover portion 22 away from the annular sleeve 21 and arranged toward each other, and a porous structure ring portion 24 fixedly connected in the shielding portion 23 and having a U-shaped cross-section. The top and bottom of the outer ring of the annular sleeve 21 are respectively provided with a water inlet through hole 1701 and a water outlet through hole 1801 connected to the active cavity. There are two ventilation arc channels 1901, and the two ventilation arc channels 1901 are symmetrically arranged on both sides of the water outlet through hole 1801. The lower end of the ventilation arc channel 1901 is provided with an outer ring of the annular sleeve 21, and the upper end of the ventilation arc channel 1901 extends into the annular sleeve 21. The top of the outer ring of the annular sleeve 21 is provided with a water inlet through hole 1701 connected to the active cavity. The annular sleeve 21 is fixedly connected to an exhaust hole 2001 connected to the movable cavity, and the annular sleeve 21 is fixedly connected to a pressure relief valve 20 connected to the exhaust hole 2001. The annular sleeve 21 is fixedly connected to a water inlet pipe joint 17 connected to the water inlet through hole 1701, and a water outlet pipe joint 18 connected to the water outlet through hole 1801. The annular sleeve 21 is fixedly connected to an air inlet pipe joint 19 connected to the lower end of the ventilation arc 1901. The air inlet pipe joint 19 is connected to an air compressor through an air inlet pipe, the water inlet pipe joint 17 is connected to a chiller through an water inlet pipe, and the water outlet pipe joint 18 is connected to a water outlet pipe. The water outlet pipe, the water inlet pipe and the air inlet pipe are all connected to an electromagnetic valve. The outer ring of the annular sleeve 21 is provided with a mounting through hole connected to the movable cavity, and a second temperature sensor is fixedly connected in the mounting through hole, and the probe of the second temperature sensor extends into the movable cavity.

[0060] When the main shaft 9 rotates, the main shaft 9 will drive the fixed water storage cover 15 fixed on its outer ring to rotate, and the annular sleeve 21 in the dynamic water storage cover 16 needs to be connected to the water outlet pipe, the water inlet pipe, and the air inlet pipe. Therefore, the annular sleeve 21 will remain in a fixed and static state, so that the movable cavity can always remain in a sealed state, but it will not affect the rotation of the main shaft 9 and the fixed water storage cover 15. In this process, only the compressed air from the air compressor needs to be introduced into the air inlet pipe. The compressed air enters the inner side of the dynamic water storage cover 16 through the ventilation arc 1901 and a plurality of air inlet holes 1902, and the compressed air The air can pass through the porous structure ring 24 to leave, so that the compressed air can impact on the fixed water storage cover 15, ensuring that a gap is formed between the porous structure ring 24 and the fixed water storage cover 15 for the compressed air to leave, and the dynamic water storage cover 16 and the fixed water storage cover 15 can maintain a relative rotation state, and no heat will be generated due to friction during the rotation process. In addition, the compressed air can ensure that water will not leave the gap from here, and a wind curtain can be formed by compressed air to ensure smooth rotation and good sealing performance between the dynamic water storage cover 16 and the fixed water storage cover 15.

[0061] Preferably, if Figures 5 to 8As shown, the inner circles of the two shielding parts 23 are provided with exhaust gaps 25 spaced apart from the inner and outer circles of the fixed water storage cover 15, and the width of the exhaust gaps 25 increases from bottom to top.

[0062] By setting the exhaust gap 25, the exhaust gap 25 can discharge the compressed air leaving the porous structure ring portion 24. Since the exhaust gap 25 on the inner side of the active cavity is filled with water, the water will mainly show a tendency to sink under the influence of gravity. Therefore, the width of the exhaust gap 25 is increased from bottom to top, which can ensure that water leakage is not likely to occur in the exhaust gap 25 below. The increase in the width of the upper exhaust gap 25 also makes it less likely for friction and jamming to occur between the dynamic water storage cover 16 and the fixed water storage cover 15 when the dynamic water storage cover 16 rotates due to the small gap, thereby ensuring that the main shaft 9 can rotate smoothly.

[0063] Preferably, the porous structure ring portion 24 is made of porous ceramic material.

[0064] The porous structure ring portion 24 is made of porous ceramic material, so the porous structure ring portion 24 has a higher hardness. It is not only breathable, but also will not be deformed due to force. If friction occurs when it contacts with the fixed water storage cover 15, the porous structure ring portion 24 is not prone to wear, thereby ensuring that the structure can maintain a longer service life and avoiding the situation where the structure gets stuck.

[0065] Preferably, it also includes a parameter acquisition module, a data processing module, a thermal error compensation module, and a control module. The parameter acquisition module is used to collect the thermal error displacement of the main shaft 9 and transmit it to the thermal error compensation module. The data processing module is used to calculate the heat at both ends of the main shaft 9 according to the temperature of the brake drum 12 and the water temperature in the active cavity and feed it back to the thermal error compensation module. The thermal error compensation module compensates for the thermal elongation error and thermal drift error of the main shaft 9 according to the thermal error displacement of the main shaft 9 and the heat at both ends of the main shaft 9. The control module controls the active cavity to complete the water exchange action according to the water temperature in the active cavity. The parameter acquisition module includes a displacement sensor, the data processing module and the parameter acquisition module both include a processor, and the control module includes a microcontroller, which is coupled to each solenoid valve.

[0066] Preferably, the data processing module is used to calculate the heat at both ends of the spindle according to the brake drum temperature and the water temperature in the active cavity and feed it back to the thermal error compensation module, including the following steps:

[0067] Define the end of the spindle connected to the brake disc as the left end of the spindle, and the end of the spindle connected to the three-jaw chuck as the right end of the spindle. The three active cavities are defined from left to right as the first active cavity, the second active cavity, and the third active cavity. Define the heat source temperature T of the left end of the spindle corresponding to the first active cavity 左, the temperature of the heat source connected to the right end of the spindle corresponding to the third active cavity is T 右 ;

[0068] Establish the cavity water temperature change equation, Among them, h i is the convective heat transfer coefficient, c 水 is the specific heat capacity of water, T i is the temperature of the water in the i-th active chamber, T p,i is the temperature of the spindle at the i-th active cavity, A i is the heat exchange area between the ith active cavity and the main shaft, m i The mass of water in the ith active cavity;

[0069] Establish the temperature variation equation of the spindle section Among them, k 主轴 is the thermal conductivity of the spindle material, c 主轴 is the specific heat capacity of the spindle material, m p,i is the mass of the spindle corresponding to the i-th active cavity, A 横截 is the cross-sectional area of ​​the main axis, T 邻左 and T 邻右 is the temperature of the spindle or heat source at the corresponding adjacent active cavity, L 邻左 and L 邻右 is the length of the main axis at the corresponding position of the adjacent active cavity;

[0070] The solution is obtained by combining the water temperature in the active cavity with the Euler method formula. The Euler method formula includes

[0071]

[0072] The goal is to minimize the error between the water temperature detection data and the model prediction value, and define the loss function as the mean square error between the measured temperature and the predicted temperature. The temperature T of the heat sources at both ends is iteratively corrected using the gradient descent optimization algorithm. 左 and T 右 , until convergence, output heat source temperature T 左 and T 右 ;

[0073] The heat source temperature T 左 and T 右 Switch to left end heat and right end heat.

[0074] The spindle 9 is divided into a left end (brake disc 11 side) and a right end (three-jaw chuck 10 side), corresponding to three active cavities (1st to 3rd cavities). By defining the heat source temperature, a correlation model between the heat input at both ends of the spindle 9 and the water temperature of the active cavity is constructed to achieve accurate segmented analysis of heat transfer. The cavity water temperature change equation describes the change of water temperature in the i-th active cavity with time, where the convective heat transfer coefficient, heat exchange area, spindle 9 temperature and the heat capacity of water jointly determine the heat exchange rate. The spindle 9 segment temperature change equation combines the thermal conductivity of the spindle 9 material, the temperature gradient of the adjacent sections, and the heat absorption effect of the water cooling system to form a dynamic equilibrium model of the spindle 9 temperature field. The Euler method is used to discretize and solve the differential equation, and the heat source temperature is iteratively corrected through the gradient descent algorithm to minimize the mean square error between the measured water temperature and the model prediction value. Finally, the optimized heat source temperature is output and converted into heat data.

[0075] Through partition modeling and dynamic equations, the system can infer the actual heat source temperature at both ends of the spindle 9 from the water temperature data, overcoming the limitation of the traditional indirect method relying on the bearing temperature. The data basis for thermal error compensation is more reliable. The discrete solution of the Euler method combined with the gradient descent optimization enables the model to respond to temperature changes in real time, which is especially suitable for complex scenarios of transient heat loads in high-speed machining, ensuring the timeliness of the compensation algorithm. The introduction of numerical methods avoids the stringent requirements of traditional analytical solutions on boundary conditions. At the same time, the gradient descent algorithm ensures the calculation stability through local optimal convergence, taking into account both accuracy and computational efficiency, and coupling the heat conduction, convection heat transfer and the material properties of the spindle 9 to model, comprehensively reflecting the thermal-mechanical interaction effect, and providing theoretical support for the separate compensation of thermal elongation error and thermal drift error.

[0076] Preferably, the data processing module is used to calculate the heat at both ends of the spindle according to the brake drum temperature and the water temperature in the active cavity and feed it back to the thermal error compensation module, and also includes the following steps:

[0077] Calculate the first heat Q absorbed by the brake pad pad =m pad ·c pad ΔT pad , m pad =ρ pad ·A contact ·h pad , where m pad is the mass of the brake drum, c pad is the specific heat capacity of the brake drum, ΔT pad is the average temperature rise of the brake drum, ρ pad is the density of the brake drum, A contact is the contact area between the brake drum and the brake disc, h pad is the thickness of the brake drum;

[0078] Based on the first heat Q padCombined with the thermal resistance ratio of the brake drum and the brake disc, calculate the second heat absorbed by the brake disc Among them, the thermal resistance of the brake drum is The thermal resistance of the brake disc is h disc is the thickness of the brake disc, k pad and k disc are the thermal conductivities of the brake drum and brake disc, respectively;

[0079] The second heat Q disc_initial Converted to the temperature of the brake disc to calculate the difference ΔT from the main shaft disc ;

[0080] According to the thermal conductivity, contact area, thickness and the difference ΔT between the brake disc and the main axis disc , the third heat transferred from the brake disc to the spindle is calculated by the steady-state heat conduction model t is the heat transfer time;

[0081] Calculate the difference between the third heat and the left heat, which is defined as the left loss heat;

[0082] The left heat loss is adjusted by the ratio of the left end heat to the right end heat to obtain the right heat loss. The sum of the right heat loss and the right end heat is defined as the fourth heat from the three-jaw chuck to the spindle. The third heat and the fourth heat are output as the heat at both ends of the spindle to the thermal error compensation module.

[0083] The heat absorption calculation of the brake drum 12 is based on the temperature rise, material properties, and geometric parameters of the brake drum 12. The first heat absorbed by the brake drum 12 is calculated, and the initial energy of frictional heat generation is quantified. The heat is distributed proportionally through the thermal resistance ratio of the brake drum 12 and the brake disc 11, and is proportionally distributed to the brake disc 11 to obtain the second heat absorbed by it. The thermal resistance calculation combines the thermal conductivity and thickness of the material to reflect the impedance characteristics of the heat transfer path. The steady-state heat conduction modeling is based on the temperature difference between the brake disc 11 and the main shaft 9. The steady-state model is used to calculate the third heat transferred to the main shaft 9. The heat difference at the left end (left heat loss) and the heat ratio at the right end are combined to adjust the heat at both ends of the main shaft 9 (the third heat and the fourth heat).

[0084] Precise quantification of the heat transfer path Through the thermal resistance ratio distribution and steady-state model, the system can accurately track the heat transfer chain from the brake drum 12 to the spindle 9, avoiding the estimation deviation caused by ignoring the thermal resistance difference in the traditional method. The dynamic adjustment mechanism of the left-end heat loss and the right-end heat effectively compensates for the energy loss in the heat transfer process (such as heat dissipation and contact thermal resistance), making the heat calculation at both ends of the spindle 9 closer to the actual working conditions, and separating the heat contribution of the brake system and the cutting heat source. Provide independent heat input parameters for the thermal error compensation module, which is convenient for targeted correction of thermal elongation and thermal drift errors. The heat calculation model based on material properties and geometric parameters can be directly adapted to brake components of different specifications, enhancing the system's versatility and scalability in diversified processing scenarios.

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A spindle low temperature brake stabilization CNC machine tool, characterized in that: The invention comprises a lathe (1), a shell (2) fixedly connected to the lathe (1), a lower axle box (4) fixedly connected to the lathe (1) and located in the shell (2), an upper axle box (5) detachably connected to the lower axle box (4), a main shaft (9) rotatably connected between the upper axle box (5) and the lower axis through two bearings and having two ends passing through the main shaft, and a driving motor (3) fixedly connected to the lathe (1), one end of the main shaft (9) is fixedly connected to a brake disc (11), the outer side of the main shaft (9) is sleeved with a brake drum (12) which can be moved back and forth along the length direction thereof, one end of the main shaft (9) connected to the brake disc (11) is transmission-connected to the driving motor (3), and the other end of the main shaft (9) passes through the shell (2) and is fixedly connected to a three-jaw chuck ( 10), the outer ring of the main shaft (9) is fixedly connected with four groups of fixed water storage covers (15) which are arranged at intervals and are located between two bearings and are in an annular shape, and a rotatable dynamic water storage cover (16) is sleeved between adjacent fixed water storage covers (15), and an active cavity is formed between the adjacent fixed water storage covers (15), the dynamic water storage cover (16), and the outer ring of the main shaft (9), and water can be set in and out of the active cavity, and an exhaust gap (25) is provided between the dynamic water storage cover (16) and the fixed water storage cover (15), and the outer ring of the dynamic water storage cover (16) is provided with a ventilation arc (1901) located therein, and the inner wall of the ventilation arc (1901) is provided with an air inlet (1902) connected to the exhaust gap (25), and the ventilation arc (1901) continuously passes compressed air.

2. A spindle low temperature brake stabilization CNC machine tool according to claim 1, characterized in that: A driving wheel (6) is fixedly connected to the rotor shaft of the driving motor (3), and a driven wheel (8) is fixedly connected to one end of the main shaft (9) away from the three-jaw chuck (10), and the driving wheel (6) and the driven wheel (8) are connected in transmission via a transmission belt (7).

3. The spindle low temperature brake stabilization CNC machine tool according to claim 1, characterized in that: A horizontally arranged hydraulic rod is fixedly connected to the inner wall of the shell (2); a connecting groove (14) and a plurality of detection through holes are provided on the side of the brake drum (12) away from the brake disc (11); a mounting tube (13) communicating with the detection through holes is fixedly connected to the side of the brake drum (12) away from the brake disc (11); a first temperature sensor is fixedly connected inside the mounting tube (13); a piston rod of the hydraulic rod is fixedly connected to a U-shaped connecting frame, and the connecting frame is fixedly connected to the connecting groove (14) by bolts.

4. The spindle low temperature brake stabilization CNC machine tool according to claim 1, characterized in that: The dynamic water storage cover (16) comprises an annular sleeve (21), a double-ring cover (22) fixedly connected to the inner and outer circles on both sides of the annular sleeve (21), a shielding part (23) fixedly connected to one end of the double-ring cover (22) away from the annular sleeve (21) and arranged facing each other, and a porous structure ring part (24) fixedly connected to the shielding part (23) and having a U-shaped cross section. The top and bottom of the outer circle of the annular sleeve (21) are respectively provided with water inlet holes connected to the movable cavity. The venting arc channel (1901) is provided with two venting arc channels (1901), which are symmetrically arranged on both sides of the water outlet through hole (1801), and the lower end of the venting arc channel (1901) is provided with an outer ring of the annular sleeve (21), the upper end of the venting arc channel (1901) extends into the annular sleeve (21), and the top of the outer ring of the annular sleeve (21) is provided with a movable The annular sleeve (21) is fixedly connected to an exhaust hole (2001) connected to the exhaust hole (2001), the annular sleeve (21) is fixedly connected to an inlet pipe joint (17) connected to the water inlet through hole (1701), and a water outlet pipe joint (18) connected to the water outlet through hole (1801), and the annular sleeve (21) is fixedly connected to an inlet pipe joint (19) connected to the lower end of the ventilation arc channel (1901). The air inlet pipe joint (19) is connected to an air compressor via an air inlet pipe, the water inlet pipe joint (17) is connected to a chiller via a water inlet pipe, the water outlet pipe joint (18) is connected to a water outlet pipe, the water outlet pipe, the water inlet pipe and the air inlet pipe are all connected to a solenoid valve, the outer ring of the annular sleeve (21) is provided with a mounting through hole connected to the active cavity, a second temperature sensor is fixedly connected in the mounting through hole, and a probe of the second temperature sensor extends into the active cavity.

5. The spindle low temperature brake stabilization CNC machine tool according to claim 4, characterized in that: The inner circles of the two shielding parts (23) are provided with exhaust gaps (25) spaced apart from the inner and outer circles of the fixed water storage cover (15), and the width of the exhaust gaps (25) increases from bottom to top.

6. The spindle low temperature brake stabilization CNC machine tool according to claim 4, characterized in that: The porous structure ring portion (24) is made of porous ceramic material.

7. The spindle low temperature brake stabilization CNC machine tool according to claim 4, characterized in that: It also includes a parameter acquisition module, a data processing module, a thermal error compensation module, and a control module. The parameter acquisition module is used to acquire the thermal error displacement of the spindle (9) and transmit it to the thermal error compensation module. The data processing module is used to calculate the heat at both ends of the spindle (9) according to the temperature of the brake drum (12) and the water temperature in the active cavity and feed it back to the thermal error compensation module. The thermal error compensation module compensates for the thermal elongation error and thermal drift error of the spindle (9) according to the thermal error displacement of the spindle (9) and the heat at both ends of the spindle (9). The control module controls the active cavity according to the water temperature in the active cavity to complete the water exchange action.

8. The spindle low temperature brake stabilization CNC machine tool according to claim 7, characterized in that: The parameter acquisition module includes a displacement sensor, the data processing module and the parameter acquisition module both include a processor, and the control module includes a microcontroller, which is coupled to each solenoid valve.

9. The spindle low temperature brake stabilization CNC machine tool according to claim 7, characterized in that: The data processing module is used to calculate the heat at both ends of the main shaft according to the brake drum temperature and the water temperature in the active cavity and feed it back to the thermal error compensation module, including the following steps: Define the end of the spindle connected to the brake disc as the left end of the spindle, and the end of the spindle connected to the three-jaw chuck as the right end of the spindle. The three active cavities are defined from left to right as the first active cavity, the second active cavity, and the third active cavity. Define the heat source temperature T of the left end of the spindle corresponding to the first active cavity 左 , the temperature of the heat source connected to the right end of the spindle corresponding to the third active cavity is T 右 ; Establish the cavity water temperature change equation, Among them, h i is the convective heat transfer coefficient, c 水 is the specific heat capacity of water, T i is the temperature of the water in the i-th active chamber, T p,i is the temperature of the spindle at the i-th active cavity, A i is the heat exchange area between the ith active cavity and the main shaft, m i The mass of water in the ith active cavity; Establish the temperature variation equation of the spindle section Among them, k 主轴 is the thermal conductivity of the spindle material, c 主轴 is the specific heat capacity of the spindle material, m p,i is the mass of the spindle corresponding to the i-th active cavity, A 横截 is the cross-sectional area of ​​the main axis, T 邻左 and T 邻右 is the temperature of the spindle or heat source at the corresponding adjacent active cavity, L 邻左 and L 邻右 is the length of the main axis at the corresponding position of the adjacent active cavity; The solution is obtained by combining the water temperature in the active cavity with the Euler method formula, and the Euler method formula includes The goal is to minimize the error between the water temperature detection data and the model prediction value, and define the loss function as the mean square error between the measured temperature and the predicted temperature. The temperature T of the heat sources at both ends is iteratively corrected using the gradient descent optimization algorithm. 左 and T 右 , until convergence, output heat source temperature T 左 and T 右 ; The heat source temperature T 左 and T 右 Switch to left end heat and right end heat.

10. A spindle low temperature brake stabilization CNC machine tool according to claim 9, characterized in that: The data processing module is used to calculate the heat at both ends of the spindle according to the brake drum temperature and the water temperature in the active cavity and feed it back to the thermal error compensation module, and also includes the following steps: Calculate the first heat Q absorbed by the brake pad pad =m pad ·c pad ΔT pad , m pad =ρ pad ·A contact ·h pad , where m pad is the mass of the brake drum, c pad is the specific heat capacity of the brake drum, ΔT pad is the average temperature rise of the brake drum, ρ pad is the density of the brake drum, A contact is the contact area between the brake drum and the brake disc, h pad is the thickness of the brake drum; Based on the first heat Q pad Combined with the thermal resistance ratio of the brake drum and the brake disc, calculate the second heat absorbed by the brake disc Among them, the thermal resistance of the brake drum is The thermal resistance of the brake disc is h disc is the thickness of the brake disc, k pad and k disc are the thermal conductivities of the brake drum and brake disc, respectively; The second heat Q disc_initial Converted to the temperature of the brake disc to calculate the difference ΔT from the main shaft disc ; According to the thermal conductivity, contact area, thickness and the difference ΔT between the brake disc and the main axis disc , the third heat transferred from the brake disc to the spindle is calculated by the steady-state heat conduction model t is the heat transfer time; Calculate the difference between the third heat and the left heat, which is defined as the left loss heat; Adjust the left heat loss to get the right heat loss by the ratio of the left heat to the right heat Heat, the sum of the right loss heat and the right end heat is defined as the fourth heat from the three-jaw chuck to the spindle, The third heat and the fourth heat are output as heat at both ends of the spindle to the thermal error compensation module.

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