High speed machining (HSM) is the most important advanced manufacturing technology in die and mould manufacturing, which is high efficiency, high quality and low consumption. A series of problems in conventional cutting are solved by the application of high speed machining.
Compared with the traditional cutting process, the cutting speed and feed speed are increased by a series of steps, and the cutting mechanism is changed fundamentally. Compared with traditional cutting, high-speed machining has taken an essential leap, the metal removal rate per unit power is increased by 30% ~ 40% , the cutting force is reduced by 30% , the cutting life of the tool is increased by 70% , and the cutting heat left on the workpiece is greatly reduced, the low-order cutting vibration almost disappears.
With the increase of cutting speed, the removal rate of raw material per unit time increases, the cutting time decreases, and the processing efficiency increases, which shortens the manufacturing cycle and improves the market competitiveness of products. At the same time, the cutting force is reduced and the chips are removed at high speed, the cutting force and thermal stress deformation of the workpiece are reduced, and the possibility of cutting thin-walled parts with poor rigidity is improved. Due to the reduction of cutting force and the increase of rotating speed, the working frequency of the cutting system is far away from the low natural frequency of the machine tool, and the Surface roughness of the workpiece is most sensitive to the low natural frequency, thus reducing the Surface roughness.
In the process of machining high hardened steel parts (hrc45 ~ 65) of dies, high speed can be used to replace electric machining and grinding and polishing, which avoids electrode manufacturing and time-consuming electric machining, and greatly reduces the amount of fitter's grinding and polishing. Some of the market more and more need of thin-walled die workpiece, high-speed milling can be successfully completed. And in high-speed milling CNC machining center, mold clamping can complete multi-step processing. These advantages are very suitable in industries such as mould with fast capital turnover, urgent delivery time and fierce product competition.
The high-speed machining system is mainly composed of high-speed machining center, high-performance tool clamping system, high-speed tool, high-speed cam software system, etc. , high speed machining is essentially a big systems engineering. With the development of cutting tool technology, high speed machining can be used to process Alloy Steel (HRC & GT; 30) , and is widely used to process parts such as stamping dies and injection moulds in automobile and electronic component products. The definition of high speed machining depends on the type of workpiece material to be machined. For example, high-speed machining of alloy steel uses a cutting speed of 500m / Min, which is the normal milling speed when machining aluminum alloys.
With the expansion of the application of high speed machining, the research of new tool materials, the improvement of tool design structure, the creation of new NC tool path strategy and the improvement of cutting conditions are also improved. In addition, the computer-aided simulation technology of cutting process has also appeared, which is very useful to predict the temperature, stress and prolong the service life of cutting tools. Casting, stamping, hot pressing and injection molding applications represent the expansion of high-speed applications of cast iron, cast steel and alloy steel. The leading countries in the industry in die and mold manufacturing, development time spent most of the machining and polishing processes. The machining and polishing of stamping die or casting die account for about 2 / 3 of the total machining cost, and high-speed milling can be used to shorten the development cycle and reduce the processing cost.
High speed is being used more and more widely in industry because of its obvious advantages over traditional processing, specifically the following characteristics:
(1) more efficient production.
High-speed machining allows the use of a larger feed rate, compared with conventional cutting 5 to 10 times higher, unit time material removal rate can be increased by 3 to 6 times. Processing time can be greatly reduced when a large number of metal parts need to be removed.
(2) reduce cutting force by at least 30% .
Because of the extremely shallow cutting depth and narrow cutting width used at high speed, the cutting force is small, compared with conventional cutting, cutting force can be reduced by at least 30% , which can reduce machining deformation for less rigid parts, it makes it possible to cut some thin-walled fine workpieces.
(3) the quality of processing has been improved.
Because the exciting frequency of cutting tool is far away from the natural frequency of the process system, the forced vibration of the process system can not be caused, and the better processing state can be ensured. Because the cutting depth, cutting width and cutting force are very small, the deformation of tool and workpiece is small, the accuracy of dimension is kept, the cutting failure layer is thin, the residual stress is small, and the high precision and low roughness machining is realized.
From the dynamic analysis of the frequency formation, it can be seen that the reduction of the cutting force will reduce the amplitude of the vibration (i. e. forced vibration) caused by the cutting force, and the increase of the rotation speed will make the working frequency of the cutting system far away from the natural frequency of the machine tool, avoid the occurrence of resonance; therefore high speed can greatly reduce the processing Surface roughness, improve the processing quality.
(4) to reduce energy consumption in processing and save manufacturing resources.
Due to the high metal removal rate per unit power, low energy consumption and the short time of the workpiece in production, the utilization of energy and equipment is improved, and the proportion of cutting process in the total resources of the manufacturing system is reduced, meeting the requirements of sustainable development.
(5) simplified the process flow.
The quenched material can not be processed by conventional cutting. The quenched deformation must be repaired manually or solved by electrical discharge machining. At high speed, the quenched material can be processed directly. In many cases, the electrical discharge machining process can be completely eliminated, the surface hardening problem caused by electrical discharge machining is eliminated, and the artificial finishing process is reduced or eliminated.
