CNC Lathe transformation methods and design
Currently CNC transformation of the market in the country there is still much room for development, the country is now CNC rate of less than 3%. Machining with an ordinary product into the prevalence of poor quality, less variety, low-grade, high interest rates, long delivery period, resulting in the international and domestic market, lack of competitiveness, the direct impact on a company's products, markets, efficiency, affect survival and development, so must greatly improve the rate of NC machine tools. In this paper, CNC lathe transformation, for example, introduced CNC transformation method, including its structural transformation of design, performance and accuracy of the selection and final determination of rehabilitation programs.
1, the significance of CNC transformation
1) save money. CNC machine tools transformation compared with the purchase of new machine can save about 60% of the general cost of large and special equipment is particularly evident. General transformation of large machine takes only a new machine purchase costs 1/3 of the original structure of the machine even for complete upgrading also just buy a new machine to spend 60% of costs, and can take advantage of existing foundations.
2) stable and reliable performance. Because the original machine after a temporary limitation of the basic pieces, almost never happens stress deformation affecting accuracy.
3 to improve production efficiency. After transformation, the machine can be realized by the CNC machining machine tool automation to improve efficiency comparable radical 3-5 times. The higher the degree of difficulty in terms of complex parts to improve efficiency the more. Tooling and can no or little use, not only saves money but also can shorten the production preparation period.
2, CNC lathe Reconstruction Design
Transformation of CNC machine tools, mainly on the structure of the original machine inventive design, and ultimately enable the machine to achieve the ideal state. Mechatronics CNC lathe is a typical representative of the mechanical structure of the machine with the ordinary has many similarities. However, modern CNC machine tools is not simply on the radical machine is equipped with CNC system can be, nor is it based on the radical machine, only to be improved locally made (those affected by the financial and other constraints, but will be converted into the radical suggestion CNC machine tools the machine is another matter), there are some weaknesses in the radical machine, such as the lack of rigidity, vibration, poor thermal deformation, friction sliding surface large gap exists between the transmission element and so on, could not do the CNC machine on the machining accuracy, surface quality , productivity, and service life requirements. Modern CNC technology, especially processing center, whether it is the supporting parts, main drive, the feed drive system, tool systems, auxiliary functions component structure, or the overall layout, exterior styling and so has undergone great changes have forming a unique mechanical structure of CNC machine tools. Therefore, the general machine tools for numerical transformation process, each case should be considered, so that the performance indicators in general machine tools and CNC machine tools as much as possible close to.
3, performance and precision CNC lathes choice
Not all of the old machine can be carried out numerical transformation, the transformation of the machine should have two main conditions: first, the basic pieces of the machine must have sufficient rigidity. Second, the cost of reconstruction to the right, the economy is good. Lathe modified before the machine's performance to make a decision. The lathe can be modified workpiece swing diameter and the maximum length of the main motor power, etc. are generally not changed. Workpiece flatness, straightness, cylindricity and roughness remains largely depends on the machine's own original levels. Mainly has the following performance and accuracy before conversion select OK.
1) axis shift method, series, speed range, the power and the need for CNC parking brake and so on.
2) the feed movement:
Feed rate: Z direction (typically 8400mm/minX to (usually 2100mm/min
Fast-moving: Z direction (typically 1.24m/minX to (usually 1.23m/min
Pulse equivalent: 0.0250.005mm within selected for the X to the Z is usually 2 times.
Processing pitch range: including pitch type can be processed (metric, inch, module, pitch and taper thread, etc.) generally pitch less than 10mm are not difficult to achieve
3) the feed movement drive (generally use stepper motor driver)
4) the need for motion transmission converted into ball screw drive.
5) the need to configure automatic turret indexing turret, workers need to determine if the configuration bits.
6) Other performance indicators options:
Interpolation: lathe need to have linear and circular interpolation function.
Tool offset and backlash compensation: In order to ensure a certain degree of precision, the general need to consider setting tool compensation and clearance compensate function.
Display: The LED or LCD or display, shows the median number of other issues lathe functions according to actual needs, in general, the lower the interest shown more simple, and easy to implement.
Diagnostic functions: to prevent the operator to enter a sequence of errors and the resulting fault action, the transformation in the NC system can be added to the necessary devices and software to enable it to indicate the function of the machine failure or partial failure, to achieve limited diagnostic capabilities.
These are lathe CNC retrofit to consider some common performance indicators, some Lathe also needed some special requirements, such as turning a large pitch thread, poor working environment dust interference, such as turning the knife precision , this time should be targeted specifically designed.
4, CNC lathe transformation program selection
When performance and precision CNC lathes and other content basic selected, can be determined according to this transformation program. Currently CNC transformation technology has become increasingly mature, dedicated to CNC transformation systems with the performance and functionality can meet the general practice of lathe processing requirements. Therefore, the more typical rehabilitation programs can be selected as CNC lathes: Lathe CNC configure a dedicated transformation systems, replacement of the feed movement of the sliding screw drive for the ball screw drive, driven by a stepping motor feed movement, configure the pulse generator to achieve thread processing functions, configure automatic indexing turret automatic tool change function.
At present, more typical economic transformation of special lathe CNC system has the following basic configuration and functions:
1) using single-chip microcomputer as the master CPU has a linear and circular interpolation, code programming, tool offset and compensate for the gap function, digital two coordinate simultaneous display, automatic indexing turret control, threading and other control functions.
2) equipped with a stepper motor drive system, pulse equivalent or control accuracy is generally: Z to 0.01mmX is 0.005mm to lead to the screw with the corresponding matching)
3) processing the order mostly by panel key input, the code compiled, maintained automatically power down memory storage; can order on-site editing and commissioning operations.
4) with a single step or continuous execution order, the order of execution cycles, mechanical limit position automatic limit overtravel alarm, and the feed speed sequential automatic termination of all types of CNC basic functions.
