CNC forming wheel gear grinding machine adopts the latest design concept of forming wheel gear grinding machine. It is a complex high-end equipment which integrates mechanical, electrical, hydraulic, automation technology, servo control technology, precision measurement technology, computer software technology. and other disciplines and technologies. CNC machine tools can process straight (inclined) involute gears and other arbitrary tooth shapes, such as cycloid gears, arc gears, etc., with the characteristics of high efficiency, high precision and high reliability.
1. High efficiency
Form grinding is used, the grinding wheel and the gear are in linear contact, and the grinding rate is high; The machine tool is equipped with a high-pressure, large-flow cooling device, which is suitable for large powers. Cutting depth grinding processing reduces the number of coarse grinding cycles and improves the grinding efficiency of the machine tool. This is a traditional machine tool that is 3 to 5 times more efficient.
2. High precision
By adopting digital servo system, selecting high precision grating ruler and fully closed loop control, the movement is smooth and without impact, achieving high movement precision. The grinding expert system has an error correction function, which can compensate for the grinding processing; errors and improve the grinding precision of machine tools.
3. High reliability
A high-rigidity design is used to ensure high geometric accuracy of the machine tool; measures such as cooling spray and temperature control are arranged at the thermal key points of the machine tool to ensure the thermal stability of the machine tool equipped with it; with various sensors such as temperature, pressure, flow and vibration to monitor the work of the machine tool. The status is monitored in real time to ensure high reliability and stability of the machine tool.
1. Design and manufacturing technology of large-scale CNC forming gear grinding machine
(1) Modular design technology
The machine tool adopts vertical structure and modular design to shorten the development cycle and improve the reliability of the machine tool. The machine tool mainly includes bed, column, workbench, workpiece column, sliding plate, dresser, grinding tool and other components. The layout of the machine tool is shown in Figure 2.
Figure 2 Layout diagram of gear grinding machine module
(2) High rigidity design and manufacturing
Shape grinding has a large load and requires high rigidity of the machine tool. During the design, finite element analysis and structural optimization were carried out on the entire machine tool and key components to ensure high rigidity of the machine tool. Modal experimental analysis was carried out on key components to make the natural frequency of the machine tool much higher than the natural frequency of the machine tool. excitation frequency during grinding; Key joint surfaces are precisely scraped to ensure contact rigidity.
(3) Thermal characteristic control technology of large gear grinding machines
During the working process of a large gear grinding machine, thermal deformation occurs under the combined action of internal and external heat sources, which affects the relative position between the workpiece and the grinding wheel, resulting in a reduction in the precision of gear processing. Research shows that in precision machining, the proportion of processing errors caused by thermal deformation reaches 40-70%. Therefore, reducing thermal deformation and achieving thermal equilibrium of the machine tool as quickly as possible is crucial to improve processing precision and stability.
The main methods adopted for this are:
① Thermal symmetry design of machine tools and optimization of cooling flow channels. Through the finite element analysis of the thermal deformation of the machine tool, the layout of the machine tool is optimized, a thermally symmetrical structure is adopted, the design of the bed flow channel is optimized, the flow of Coolant around the bed is increased, the temperature distribution is more uniform. , and the thermal characteristics of the machine tool are improved.
Figure 3 Cloud diagram of temperature field of gear grinding machine Figure 4 Cloud diagram of deformation of complete machine after improvement of flow channel
②Isothermal grinding control technology. Real-time detection of machine tool internal and external ambient temperature, automatic adjustment of grinding coolant temperature, maintaining the difference between machine tool internal temperature and ambient temperature within a stable range, reducing errors caused by thermal deformation, minimizing deformation during the working process of the machine tool, and meeting the needs of high-precision grinding Cutting requirements.
(4) Design and manufacturing technology of static pressure guide rails and static pressure bearings. Enclosed hydrostatic guide rail is used to solve the problem of creeping and hysteresis in linear guide rails under heavy loads. The repeatable positioning accuracy of the linear axis reaches 0.002mm, the positioning accuracy of the rotary axis reaches ±3 arc seconds, and the positioning accuracy of the rotary axis reaches ±3 arc seconds. The maximum load capacity of the machine tool is 2t, meeting the product design requirements.
(5) Applications of composite materials. During the machine tool assembly process, adjusting the geometric accuracy requires several scrapings of the guide rail joint surface. When scraping the joint surface of large machine tools, the workload of lifting, turning and scraping large parts is very heavy. used to achieve one-time finalization of the precision of the machine tool guide rail. It can meet precision requirements, reduce assembly workload, and improve the assembly precision of machine tools.
2. Development of a grinding expert system
Grinding expert system is the core software system of shape grinding wheel gear grinding machine. It solves the problem of tedious computer programming for machine tool operators. It can recommend grinding processes according to user requirements for grinding parts, allowing users to choose different ones. grinding methods. , grinding wheel dressing method, automatically generates machine tool processing programs, guides users to perform precise and efficient grinding, and improves the processing efficiency of machine tools.
The main functional modules are as follows:
(1) Modification of tooth profile based on optimization of mesh errors under working conditions
Gearbox gears produce edge contact due to machining, assembly errors, load deformation, etc., resulting in stress concentration, which has a significant impact on the stability and the life of the transmission. Therefore, the tooth profile must be precisely modified to reduce edge contact and stress. concentration. The machine tool adopts shape grinding, which can change the tooth profile through precise interpolation of the fully enclosed servo axis to achieve precise three-dimensional modification of the tooth profile.
Figure 5 Three-dimensional graphs of tooth profile change
(2) Tooth surface distortion control technology
When grinding helical gears, the contact line between the grinding wheel and the tooth surface is a spatial curve. It is necessary to adjust the intersection angle of the grinding wheel axis and the workpiece, and change the relative position of the contact line to prevent this from happening. the contact line between the grinding wheel and the two sides of the tooth surface does not detach from the tooth surface at the same time and the supporting force, the blade deflection and the distortion of the tooth surface tooth. The tooth surface distortion control technology developed by the machine tool automatically optimizes and adjusts the intersection angle of the grinding wheel axis according to the workpiece parameters, changes the relative position of the line contact and improves tooth surface distortion.
(3) Workpiece surface quality control technology
Conduct research on large gear grinding process, collect and analyze data of high-efficiency gear grinding process, and establish process parameter database. For gears with different materials and different heat treatment requirements, users can find suitable grinding process parameters. . The process parameters mainly include grinding wheel abrasive, particle size, dressing feed quantity, grinding feed speed, coolant flow and pressure, etc., guiding users to achieve precise and efficient grinding, eliminate grinding burns and cracks, and improve grinding efficiency.
(4) Intelligent monitoring of grinding status
After secondary development, the AE (acoustic emission) device built into the grinding wheel spindle can realize automatic tool adjustment of the workpiece, automatic tolerance allocation, real-time monitoring of the grinding process and the state of wear of the grinding wheel, automatic dressing control. of the grinding wheel, keeping the grinding wheel sharp and ensuring the quality of grinding. AE’s anti-collision protection function enables the machine tool to perform emergency retraction function in case of tool chewing or eccentric grinding to protect the safety of the workpiece and the machine. equipment.
3. On-machine detection and comprehensive error compensation technology
(1) On-machine measurement technology
The mass of large gears is large, and it is inconvenient to disassemble and send the gears for inspection. Measuring off-machine is time-consuming and laborious. It is very necessary to configure the on-machine measurement function on the machine tool. The machine tool’s on-machine measurement function uses the machine tool’s CNC axis to measure the gear. The measurement data is then sent back to the expert grinding system. Compared to the set target, the processing parameters of the machine tool are automatically adjusted to achieve precision grinding. under closed loop control.
The on-machine machine tool measuring system mainly measures the gear tooth shape, tooth direction, tooth pitch and cumulative total tooth pitch deviation.
Figure 6 Measurement report on machine tool on machine
(2) Comprehensive error testing and compensation technology for machine tools
The laser plotter is used to measure various errors of the servo axis of the machine tool, a spatial error model of the machine tool is established, and the dynamic operation function of the CNC system is used to compensate for the errors inter-axes. The self-developed transmission chain error tester is used to measure and analyze machine single-axis motion error, multi-axis linkage error and interpolation error, and parameters of the machine tool are adjusted to achieve the best compensation effect.
Figure 7 Field test of complete machine tool error compensation
4. Application of machine tool working status monitoring, early warning and fault diagnosis technology
(1) No additional sensor monitoring or early warning for machine tools
Through the integrated position, speed, torque, current, voltage and other interfaces of the machine tool CNC system, the dynamic response signal of the machine tool is obtained, the first characteristics Low faults of the power system of the machine tool are extracted and dynamic. errors and various amounts of vibration are monitored in real time. When the error trend begins to increase and fault signs begin to appear, early warning treatment of machine tool faults can be carried out in a timely manner to improve the stability and reliability of the machine. tool.
Figure 8 Gear grinding machine fault diagnosis software interface
(2) Application of remote fault diagnosis technology
The machine tool remote diagnosis function realizes remote control between an external computer and the machine tool’s industrial computer to perform online operations such as fault diagnosis and parameter changes on the machine -tool. When a customer’s machine tool breaks down, maintenance personnel can handle the machine tool breakdown without going to the site, thereby reducing the maintenance time of the machine tool, improving the efficiency of the machine tool work and making services to machine tool users more convenient and faster.
Daguang focuses on providing solutions such as precision CNC machining services (3-axis, 4-axis, 5-axis machining), CNC milling, 3D printing and rapid prototyping services.
