1, CNC CNC lathe processing preliminary steps. First determine the process requirements of the parts, the batch of processed workpieces, the formulation of CNC lathe should have the function of making good preparations for the reasonable selection of the prerequisites for the CNC lathe to meet the typical parts of the process requirements of the typical parts of the process requirements are mainly the structural dimensions of the parts, machining range and accuracy requirements.
2, according to the precision requirements, i.e., the workpiece dimensional accuracy, positioning accuracy and surface roughness requirements to select the control accuracy of the CNC lathe. Selected according to the reliability, reliability is to improve product quality and productivity.
3, the reliability of CNC machine tools refers to the machine tool to perform its functions under the specified conditions, a long period of stable operation without failure. That is, the average failure-free time is long, even if the failure, a short time to recover, back into use. Select a machine tool that has a reasonable structure, is well manufactured, and has been mass produced. In general, the more users, the higher the reliability of the CNC system.
4, CNC CNC lathe processing materials are: 304, 316 stainless steel, carbon steel, copper, aluminum, alloy, plastic, POM and so on. But the car of different materials need to use different quality of products, in order to ensure the accuracy of each product requirements.
Machining accuracy is mainly used to characterize the fine degree of production products, is the evaluation of machining surface geometric parameters of the term. Machining accuracy is measured in terms of tolerance grades, and the smaller the grade value, the higher the accuracy. Tolerance level from IT01, IT0, IT1, IT2, IT3 to IT18 a **** there are 20, of which IT01 said that the highest machining accuracy of the part, IT18 said that the machining accuracy of the part is the lowest, the general factory and mining machinery belongs to the IT7 level, general agricultural machinery belongs to the IT8 level. Workpiece rotation, turning tool in the plane for straight or curved movement of the cutting process. Turning is generally carried out on the lathe, used to process the workpiece's internal and external cylindrical surfaces, end surfaces, conical surfaces, forming surfaces and threads.
Turning machining accuracy is generally IT8-IT7, surface roughness of 1.6-0.8μm.
1, rough turning strive to not reduce the cutting speed under the conditions of the use of large depth of cut and large feed in order to improve the efficiency of the turning, but the machining accuracy can only be up to IT11, the surface roughness of Rα
2, semi-finish turning and fine turning try to use high speed and small feed and depth of cut, machining accuracy up to IT10-IT7, surface roughness of Rα10-0.16μm.
3, in the high-precision lathe with a fine Repair diamond lathe high-speed precision turning non-ferrous metal parts, can make the machining accuracy of IT7-IT5, surface roughness of Rα0.04-0.01μm, this kind of turning is called mirror turning.
In the actual production process, it will be found that the same CNC lathe operated by different people, in the same working time the productivity difference is very large, many CNC lathe processing capacity is not fully reflected, play its optimal role. In the use of the process, only fully consider the various factors affecting the productivity of CNC lathes, find ways to improve the productivity of CNC lathes, in order to make the production capacity of CNC lathes to be fully realized.
One, the development of a reasonable processing technology route, reduce the auxiliary time of CNC milling
In order to improve the productivity of CNC lathe, first of all, we must carefully analyze the parts processed by CNC lathe, figure out the material of the parts, structural characteristics and shape and position tolerance requirements, roughness, heat treatment and other aspects of the technical requirements. Then on this basis, select a reasonable milling process and concise machining route.
The development of machining process: usually a part can have several different processes, parts of the process is different, its productivity, machining costs and machining accuracy often has a significant difference, so it should be under the premise of ensuring the quality of parts machining, according to the production of specific conditions, try to improve productivity and reduce production costs, to develop a reasonable machining process.
Determination of the processing route: the correct and concise processing route, is to ensure that the processing quality and improve the efficiency of the basis. Selection of parts of the machining route, must comply with the principle of determining the machining route in order to achieve the purpose of improving production efficiency. Determine the principles of machining routes are: should be able to ensure that the machining accuracy of the parts and surface roughness requirements, and high efficiency; should try to make the shortest possible machining routes, so that both reduce the number of program segments, but also to reduce the tool idle travel time; should make the numerical calculations are simple, the number of program segments is small, in order to reduce the programming workload. In addition, to determine the machining route, but also take into account the machining allowance of the workpiece and the lathe, tool rigidity and so on, to determine whether it is a time to go, or many times to complete the processing. At the same time, should try to achieve a clamping, multi-directional machining, a machining shape. In this way, it can reduce the number of times the workpiece is mounted and effectively shorten the handling and clamping time. In this way, not only can effectively improve the processing efficiency and can well guarantee the positional accuracy requirements of the parts.
Two, choose the right tool
Selection of tools should be considered CNC lathe processing capacity, process content, workpiece materials and other factors. CNC lathe tool selection, not only requires high hardness, high wear resistance, adequate strength and toughness, high heat resistance and good workmanship, and requires dimensional stability, easy to install and adjust. Therefore, new and high-quality materials should be used to manufacture CNC machining tools, and optimize the tool parameters, so that the size of the tool is compatible with the surface size and shape of the workpiece being machined. So, how to choose the right cutting tool?
(1) Select the appropriate tool
In the cutting process of CNC lathe, the role of metal cutting tools is extremely important. Manufacturing tool materials must have high hardness, wear resistance and heat resistance, adequate strength and toughness, good thermal conductivity and processability, and good economy. In the selection of tools in the process, under the premise of meeting the requirements of parts processing, try to choose a larger diameter of the tool, the strength and toughness of the better; the same process, the number of tools selected as few as possible, in order to reduce the number of times to change the tool; as far as possible to choose the universal standard tool, do not use or less special non-standard tool.
(2) reasonably determine the tool point
The tool point is a CNC lathe processing parts, the tool relative to the starting point of the workpiece movement. Also known as the "program starting point" or "play point". Tool point selection must comply with the following principles: to facilitate digital processing and simplify programming; easy to find the right on the lathe, processing is easy to check; caused by small processing errors. The location of the tool point can be selected on the workpiece, can also be selected on the outside of the workpiece (such as fixtures or lathe), but must have a certain size relationship with the parts of the positioning reference. Tool point should be selected as far as possible in the design of parts or process benchmarks, such as hole positioning of the workpiece, the center of the hole can be selected as the tool point. The position of the tool is the hole to find the right, so that "in place" and "tool point" coincide. In this way, you can better improve the efficiency of tool setting, to ensure the quality of machining.
Three, reasonable installation and clamping of the workpiece to improve the clamping speed
Workpiece processing on the CNC lathe, workpiece positioning and installation should strive to make the design benchmarks, process benchmarks and programming calculations of the benchmarks are unified; minimize the number of times to minimize the clamping, as far as possible after a positioning and clamping, machining all the surfaces to be machined; to avoid the use of occupation of the machine to manually adjust the processing program to give full play to the effectiveness of the CNC lathe. The efficiency of the CNC lathe.
CNC lathe cutting, positioning of parts, clamping design and furniture selection and design issues to be considered in a comprehensive manner. In the design of furniture, first of all, to ensure that the direction of the coordinates of the furniture and lathe coordinate direction is relatively fixed. Secondly, to coordinate the dimensional relationship between the parts and the lathe coordinate system. At the same time, should also consider:
(1) when the parts production batch is not large, should try to use a combination of fixtures, adjustable fixtures and general-purpose fixtures, in order to shorten the production preparation time, saving production costs;
(2) in the batch production before considering the use of special fixtures, and strive for simple structure;
(3) the loading and unloading of parts should be fast, convenient, reliable, in order to shorten the Lathe downtime;
(4) fixture parts should not interfere with the lathe on the surface of the parts processing;
(5) in the selection of tooling should be conducive to the exchange of tooling, to avoid interference collision;
(6) in the batch production can also be used in more than one place, multi-piece fixture, in order to improve processing efficiency.
Four, a reasonable choice of cutting volume, improve the efficiency of the removal of machining allowances
Cutting volume includes: spindle speed, depth of cut, feed rate. In the selection of CNC milling machine cutting, if roughing, generally to improve productivity, but also consider the economy and processing costs, you can choose a larger depth of cut and feed rate; if semi-finishing and finishing, should be under the premise of ensuring the quality of machining, taking into account the efficiency, economy and cost of machining; tool to do the air movement should be set to set up as high as possible feed rate. Specific values should be based on the lathe manual, cutting manual, and combined with experience.
Fifth, the implementation of tool pre-tuning and automatic wolf measurement, reduce the occupation of machine adjustment time
CNC lathe machining process often need to use a number of different tools, if the tool can not be pre-adjusted, it is necessary for the operator to install each tool to the spindle, slowly determine the exact length and diameter. This is then entered manually via keys on the CNC control surface. If you use the tool setting instrument, you can accurately measure the diameter and length of the tool, reduce the lathe occupancy time, improve the first piece of qualified rate, greatly enhance the productivity of CNC milling machine.
Sixth, the flexible use of CNC lathes of various auxiliary functions and macro programs
CNC lathe with tool radius and length compensation function, by changing the tool compensation method to make up for the tool size error, the same machining program to achieve layered milling and roughing, finishing, or used to improve the machining accuracy, and can be used with the same machining program processing with the parts.
The use of macro programs is the biggest feature of the regular shape or size with the shortest program to indicate, and the lathe in the implementation of such programs, more than the implementation of CAD / CAM software to generate the program more quickly, the response is more rapid. Macro program can use variables and assign values to variables, variables can be operated between the program run can be jumped, you can form a modular machining program, the application only need to enter the part information, machining parameters, etc. into the corresponding module of the call statement, greatly reducing the programming and input time.
CNC lathe also has a fixed cycle function, subroutine function, mirror processing function, rotating light function, the use of these functions can be eliminated long program input, the use of proper taste can be twice the result with half the effort.