Automatic programming of CNC machining
The automatic programming of CNC machining is also called computer-aided programming, that is, most or all of the programming is done by the computer. Such as completing the calculation of coordinate values, compiling part processing procedures, automatically outputting and printing processing procedures and preparing control media.
One hundred years ago, high-speed steel cutting tools began to be used, and the cutting speed for milling ordinary steel was only 25-30m/min. Compared with carbon tool steel and alloy tool steel, the processing at that cutting speed is “high-speed milling”. Therefore, “high-speed steel” was named.
The high-speed milling system is a complex dynamic system, which is prone to chatter vibration when machining thin parts. Flutter is a very strong relative vibration between the tool and the workpiece during the milling process. This kind of vibration will destroy the relative correct position of the tool and the workpiece, and reduce the surface processing quality and milling efficiency. For a long time, cutting chatter has been a major research topic in the machinery manufacturing industry and milling processing.
Parts finishing is an algorithm based on curved surfaces. For multi-curved models, the lifting of the milling cutter should be reduced as much as possible. This requires that the generated milling tool path be within the same angular range or require different allowances in the axial and radial directions.
Ultra-precision cutting started with SPDT technology, which is supported by air bearing spindles, pneumatic slides, high rigidity, high-precision tools, feedback control, and environmental temperature control to obtain nano-level surface roughness. Diamond cutters are mostly used, which are widely used in the processing of copper flat and aspheric optical elements, plexiglass, plastic products (such as camera plastic lenses, contact lens lenses, etc.), ceramics and composite materials.
The machining center performs multi-process (turning, milling, drilling, boring, tapping, etc.) and multi-face composite processing on prismatic parts through automatic tool change and table indexing. Practice has proved that the composite machining center is indeed beneficial to solve the shortcomings of long delivery time, low resource utilization, more products in process and slow capital turnover of small and medium-sized machinery manufacturing enterprises. Turning and milling combined processing has thus gained more and more common applications in industrial production.
Difficult-to-machine materials are materials with poor turning and milling workability. Performance of this material is greater than or less indicators (HB> 250, σb> 1000 MPa, δ> 30%, αk> 100 MPa, K <41.8 W / mk) one or more, are all difficult to cut materials. It can also be measured by phenomena in the cutting process (cutting force, cutting heat, tool wear and tool durability, processed surface quality and chip control, etc.).
Cutting is roughly divided into turning, milling, and center-tooth-based cutting (end face cutting of drills and end mills, etc.). The cutting heat of these cutting processes has different effects on the cutting edge. Turning is a continuous cutting, the cutting force on the tip does not change significantly, and the cutting heat continuously acts on the cutting edge; Milling is a kind of intermittent cutting, and the milling force is intermittently acting on the tip of the blade, and vibration will occur during milling. The heat effect on the cutting edge is the heating during cutting and the cooling during non-cutting alternately, and the total amount of heat received is less than during turning.
Cemented carbide is prepared by powder metallurgy with tool steel or alloy steel as the binder phase and refractory metal carbides (mainly WC, TiC) as the hard phase. Its structure is characterized by the fine hard phase grains dispersedly distributed in the steel base. The hard phase in the alloy mainly endows the material with high hardness and high wear resistance, and the binder phase in turn endows the material with the properties of steel. Therefore, the steel-bonded cemented carbide has the comprehensive properties of steel and cemented carbide, and it has been widely used in various fields.
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