CNC lathe, turning center, is a high-precision, high-efficiency automatic machine tool. Equipped with multi-station tower or power tower, the machine tool has a wide range of processing technology performance, can process linear cylinder, oblique cylinder, arc and a variety of threads, slots, worm and other complex workpieces, with linear interpolation, arc interpolation of various compensation functions, and in the mass production of complex parts has played a good economic effect.
CNC machine tool is in accordance with the pre-prepared processing program, automatic processing of the parts to be processed. We put the parts of the processing process route, process parameters, tool movement track, displacement, cutting parameters (spindle rotation, feed, back cutting, etc.) and auxiliary functions (tool change, spindle forward rotation, reverse, cutting fluid on, off, etc.), in accordance with the CNC machine tool requirements of the instruction code and program format written into the processing program. Then record the contents of this program in the control medium (such as punched paper tape, tape, disk, bubble memory), and then input into the CNC machine tool's CNC device, so as to command the machine tool processing parts.
The whole process from the analysis of the part drawing to the manufacture of the control medium is called the preparation of the numerical control program. The difference between CNC machine tools and ordinary machine tools is that CNC machine tools automatically process parts according to the program, and ordinary machine tools are operated by people, and we can achieve the purpose of processing different parts as long as we change the program of controlling the machine tool action. Therefore, CNC machine tools are especially suitable for processing small batches and complex shapes requiring high precision parts.
Because the CNC machine tool should process parts according to the program, the programmer prepares the program and inputs it into the CNC device to command the machine tool work. The input to the program is via the control medium.
Machine tool composition
● Host, which is the main body of CNC machine tool, including machine tool body, column, spindle, feed mechanism and other mechanical parts. It is a mechanical component used to complete various cutting processes.
● Numerical control device is the core of numerical control machine tool, including hardware (printed circuit board, CRT display, key box, paper tape reader, etc.) and the corresponding software, used to input the digital part program, and complete the input information storage, data transformation, interpolation operations and the realization of various control functions.
● Drive device, which is the drive part of the CNC machine tool executive mechanism, including the spindle drive unit, feed unit, spindle motor and feed motor. He realizes spindle and feed drive by electrical or electro-hydraulic servo system under the control of numerical control device. When several feeds are linked, the processing of positioning, straight line, plane curve and space curve can be completed.
● Auxiliary devices, some necessary supporting parts of exponential control machine tools to ensure the operation of CNC machine tools, such as cooling, chip removal, lubrication, lighting, monitoring, etc. It includes hydraulic and pneumatic devices, chip removal devices, exchange tables, CNC turntables and CNC indexing heads, and also includes cutting tools and monitoring and testing devices.
● Programming and other ancillary equipment can be used for programming and storage of parts outside the machine.
Since the Massachusetts Institute of Technology developed the world's first numerical control machine tool in 1952, numerical control machine tools in the manufacturing industry, especially in the automotive, aerospace, and military industries are widely used, numerical control technology in both hardware and software, have rapid development
Three Elements
selection principle
The basic principles of determining the three elements; According to the cutting requirements, first determine the back cutting amount ap, then look up the table to get the feed, and then look up the table through the formula to calculate the main cutting speed U.
In many cases, we can determine the values of these three elements by empirical data.
Selection method
Practice has proved that the selection of reasonable cutting parameters is related to many factors such as machine tool, tool, workpiece and technology. Reasonable selection of processing dosage methods are as follows:
When roughing, it is mainly necessary to ensure higher production efficiency, so a larger back cutting quantity A should be selected. , large feed, cutting speed U choose low and medium speed.
When finishing, it mainly ensures the requirements of the size and surface accuracy of the parts, so choose a smaller back cutting amount ap and a smaller feed amount. Cutting speed U Select a higher speed.
When roughing, it is generally necessary to give full play to the potential of the machine tool and the cutting ability of the tool. When semi-finishing and finishing, we should focus on how to ensure the quality of processing, and on this basis, improve productivity as much as possible. CNC lathe factory in the selection of cutting parameters should ensure that the tool can complete a part or ensure that the durability of the tool is not less than a working class, at least not less than half the working time of the working class. The specific numerical value of CNC lathe factory should be selected according to the provisions of the machine tool manual, tool durability and practical experience.
(1) The choice of back knife measurement. The choice of the amount of back cutting should be determined according to the stiffness of the machine tool, fixture, tool and workpiece, and the power of the machine tool. As long as the process system allows, choose as large as possible. In addition to the allowance left for later processes, the rest of the roughing allowance is cut as much as possible at once to minimize the number of tool trips.
Usually on medium power machine tools, the amount of rough back cutting is 8-10 mm (unilateral). CNC lathe factory semi-finishing back cutting amount of 0.5-5 mm; When finishing, the back cutting amount is 0 2-1.5 mm.
(2) Determination of the amount of feed. The feed quantity refers to the direction of the tool feed in unit time. CNC lathe factory moving distance. The principle of determining the feed speed is: when the quality requirements of the workpiece can be guaranteed, in order to improve productivity, a higher feed speed can be selected. CNC lathe factory cutting, turning deep holes or fine turning, it is appropriate to choose a lower feed speed. The feed speed should be consistent with the spindle speed and the amount of back cutting tool. When roughing, the choice of feed rate is limited by the cutting force.
Tool selection method
Because CNC lathe processing is a work of high precision, and its processing procedures are concentrated and the number of parts clamping is less, so the use of CNC tools put forward higher requirements, the following Dongguan Tongli metal Products Co., Ltd. to introduce you.
When choosing the tool for CNC machine tool processing, the following aspects should be considered:
(1) The type, specification and accuracy level of cnc cutting tools should be able to meet the requirements of CNC lathe processing.
(2) High precision. In order to meet the high precision and automatic tool changing requirements of CNC lathe machining, the tool must have a high precision.
(3) High reliability. In order to ensure that no accidental tool damage and potential defects will occur in CNC machining and affect the smooth progress of machining, the tool and the accessories combined with it must have good reliability and strong adaptability. Precision hardware machining
(4) High durability. CNC lathe machining tools, whether in roughing or finishing, should have higher durability than ordinary machine tools used in machining, in order to minimize the number of replacement or polishing tools and knives, so as to improve the processing efficiency of CNC machine tools and ensure processing quality.
(5) Good chip breaking and chip removal performance. In cnc lathe processing, chip breaking and chip removal can not be processed manually in time like ordinary machine tool processing, chips are easy to wrap around the tool and workpiece, which will damage the tool and scratch the workpiece machined surface, and even hurt people and equipment accidents, affecting the processing quality and the safe operation of the machine tool, so the tool is required to have better chip breaking and chip removal performance.
