The main cutting motion is the rotation of the machining tool. When machining on a horizontal milling machine, the plane is formed by the cutting edge on the outer surface of the milling cutter. When machining on a vertical milling machine, the plane is formed by the end edge of the milling cutter. Yes, increasing the speed of the milling machine tool can effectively obtain a higher cutting speed, so the efficiency of production and processing is higher. However, because the cutter teeth of the milling cutter cut into and cut out of the device to form an impact, vibration is prone to occur during the cutting process, which limits the quality of surface processing. Such impacts also aggravate tool wear and damage to tools, and often lead to embrittlement of cemented carbide tools. During the period of cutting in and out of the workpiece, a certain amount of cooling can be obtained, so relatively speaking, the heat dissipation conditions are better. According to the direction of the main movement speed during milling, the direction of the main movement speed is opposite or the same as the feed direction of the workpiece, which can be divided into up-milling and Down milling two kinds;
A, up milling
It can avoid the movement phenomenon that occurs during down milling. During up milling, the cutting thickness gradually increases from zero. Therefore, the cutting edge begins to experience a stage of squeezing and sliding on the hardened machined surface, which intensifies the wear of the tool, and at the same time , When up-milling, the milling force will lift the workpiece, which is easy to cause vibration, which is the disadvantage of up-milling;
B, down milling
The horizontal separation of the milling force is the same as the feed direction of the workpiece. There is generally a gap between the workpiece mounting table and the feed screw and the fixed nut. Therefore, the cutting force is likely to cause the workpiece and the workpiece mounting table to move forward together, allowing the workpiece to move forward. Sudden increase in feed rate causes the phenomenon of "knife hitting". When milling workpieces with hardness on the surface such as castings and forgings, the down milling cutter teeth first base the workpiece on the hard skin layer, which accelerates the wear of the milling cutter.
The accuracy of milling processing can generally achieve IT8-IT7, and the surface roughness can generally achieve 6.3-1.6um. Ordinary milling processing can generally only be applied to plane processing, and a relatively fixed curved surface can also be processed with a forming milling cutter. A CNC milling machine can use software to control several axes through a CNC system to perform linkage in a certain relationship, and milling is more complicated. For curved surfaces, ball-end milling cutters are generally used at this time. The CNC milling machine has special significance for processing complex workpieces such as impeller products and mechanical pages, mold cores and cavities. Precision stamping parts, new energy stamping parts, metal stamping dies
Using rotary turning to form a turning movement. When the tool moves along the parallel axis of rotation, an inner and outer cylindrical surface is formed, and the tool moves along the oblique line that intersects the axis to form a tapered surface. On CNC lathes, controlling the tool to feed along a curve can form a specific rotating surface. Using forming tools, it can also process a rotating surface when performing transverse feed. Turning is often used for threaded surface, end face and eccentric shaft processing. The precision of turning processing is generally IT8-IT7, and the surface roughness is 6.3-1.6um. , When precision turning, it can achieve IT6-IT5, and the roughness can achieve 0.4-0.1um. Turning processing has the characteristics of high processing efficiency, stable processing and simple tools.
Grinding is the processing of a workpiece with a grinding wheel or other abrasive tools. This type of processing is relatively common. Its main movement is the rotation of the grinding wheel. The grinding process of the grinding wheel is actually the cutting, engraving and sliding of the surface of the workpiece by the abrasive particles. The comprehensive performance of this effect, during the grinding process, the abrasive particles themselves are gradually blunt from sharp, which makes the cutting effect worse and the cutting force becomes larger. When the cutting force exceeds the strength of the binder, the blunt abrasive grains fall off, exposing a new layer of abrasive grains, forming the "self-sharpening" of the grinding wheel. However, cutting and crushing abrasive particles will still block the grinding wheel. Therefore, after grinding for a period of time, the grinding wheel needs to be corrected with a diamond turning tool.
When grinding, because there are many blades, the processing is relatively stable and the processing accuracy is relatively high. The grinding machine is a finishing machine. The grinding accuracy can achieve IT6-IT4, and the surface roughness Ra can achieve 1.25-0.01um. It can reach 0.1-0.008um. Another feature of grinding is the ability to process hardened metal materials. Therefore, grinding is often used as the final processing procedure. During grinding, the heat generated is relatively large, and sufficient cutting fluid is required for cooling. According to different functions, grinding is generally divided into three processes: inner hole grinding, cylindrical grinding and flat grinding. Precision stamping parts, new energy stamping parts, metal stamping dies
4: Complex curved surface processing
Three-dimensional surface cutting processing mainly adopts copy milling and numerical control milling methods or special processing. Copy milling must have a prototype as a model. During the processing, the ball head is a copy head, which always contacts the prototype surface with a certain pressure. The movement of the profiling head is transformed into inductance, and the machining amplification controls the movement of the three axes of the milling machine to form the trajectory of the cutter head along the curved surface. Most milling cutters use ball-end milling cutters with the same radius as the profiling head. The emergence of CNC technology provides a more effective method for surface processing. When processing on a CNC milling machine or machining center, the ball-end milling cutter is used to point by point according to the coordinates. Value processing is complete. The advantage of using a machining center to process curved surfaces is that there is a tool magazine on the machining center, and the tools are generally more than a dozen or even more. For rough machining and finishing of curved surfaces, different tools can be used for different curvature radii of concave curved surfaces, and appropriate tools can also be selected. At the same time, various auxiliary surfaces, such as holes, threads, slots, etc., can be machined in one clamping. , This advantage fully guarantees the relative position accuracy of each surface.
When planing processing, the reciprocating linear motion of the purchased tool is the main cutting motion. Therefore, the speed of the planing process will not be very high, and the production efficiency will naturally be lower. Therefore, the planing process will be more stable than the milling process. The accuracy can generally achieve IT8-IT7, the surface roughness can achieve Ra6.3-1.6um, the flatness of fine planing processing can even reach 0.02/1000, and the surface roughness is 0.8-0.4um;
6: Tooth surface processing
Gear tooth surface processing methods are generally divided into two types, forming method and generating method. The machine tool used in the forming method to process the tooth surface is an ordinary milling machine, and the tool is a forming milling cutter, which requires two simple forming motions, the rotary motion and the linear motion of the tool. Commonly used machine tools for tooth surface processing by the generative method are generally gear shapers and gear hobbing machines.
Seven: Drilling and boring processing
On a drilling machine, using a drill bit to rotate holes is a common method for aperture processing. The accuracy of drilling is relatively low, generally only IT10 can be reached, and the surface roughness is generally 12.5-6.3um. The manufacturer’s general practice is to drill After the processing is completed, reaming and reaming are carried out for semi-finishing and finishing. Reaming uses a reaming drill, and reaming is generally processed with a reamer. The reaming accuracy is generally IT9-IT6, and the surface roughness is Ra1.6-0.4um. Whether it is reaming or reaming, the drill and reamer generally follow the axis of the original hole bottom hole, which cannot improve the position accuracy of the hole. Boring can correct the position of the hole. Generally, it can be done directly on a boring machine and a lathe. When boring on a boring machine, the boring tool is basically the same as the turning tool. The difference is that the workpiece does not move, the cutting tool rotates, and the accuracy of boring processing Generally IT9-IT7, the surface roughness is Ra6.3-0.8mm.
Eight: Special processing
The so-called special processing method refers to the general term of a series of processing methods that use chemical, physical or electrochemical methods to process workpiece materials, which are different from traditional cutting processing methods. These processing methods mainly include chemical processing (GHM), Electrochemical machining (ECH), electrochemical machining (ECMM), electric discharge machining (EDM), electrical contact machining (RHM), ultrasonic machining (USM), laser beam machining (LBM), ion beam machining (IBM), electronics Beam machining (EBM), plasma machining (PAM), electro-hydraulic machining (EHM), abrasive flow machining (AFM), abrasive jet machining (AJM), liquid jet machining (HDM) and various complex machining, etc.
Through the above summary and analysis, the main eight common machining methods are milling, turning, grinding, complex surface processing, planing, tooth surface processing, drilling and boring processing, special processing, etc. The types of machining that Shenzhen Hongweisheng Precision can handle are mainly milling, turning, and complex surface machining and tooth surface machining. The company has more than 100 high-precision CNC machining machines, and is also equipped with composites mentioned in special machining. The machining center has the processing performance of completing multiple processes in one clamping.