Outer circle turning, end face turning, inner hole turning, tool selection guide!
1, Outer circle turning
Ordinary cylindrical turning is the process of machining the outer surface of a part to obtain the required dimensional, positional accuracy, and surface quality. Ordinary cylindrical turning tools are divided into 95 °, 90 °, 75 °, 60 °, 45 °, etc. according to the main deviation angle of the tool. The 90 ° and 95 ° main deviation angle tools have larger axial force and smaller radial force when cutting, making them suitable for turning slender shaft parts. The 75 °, 60 °, and 45 ° main deviation angle tools are suitable for turning the outer circle of short and coarse parts, and the 45 ° main deviation angle tools can also perform 45 ° chamfering turning.
The economy of negative angle blade turning tools is better than that of positive angle blade turning tools, while positive angle blade turning tools have sharp edges and light and fast cutting. However, the size of positive angle blades is generally small and only suitable for small back feed and small feed processing. Negative angle blades can be manufactured with larger sizes and can be used for large back feed and large feed processing. The tool tip strength is also better than that of positive angle blades (blades with the same shape, size, and tool tip arc). The strength of blade edges varies with different shapes, the effective cutting edge length varies, and the number of available tool tips also varies.
2, End face turning
End face turning refers to the cutting of the workpiece's end face by the main cutting edge.
1. Precautions for the end face of the vehicle
1) The tip of the turning tool should be aligned with the center of the workpiece to avoid leaving a protrusion in the center of the end face that is turned.
2) When the back cutting amount is large, it is easy to puncture the end face of the biased cutting tool. Selection of back cutting amount ap: ap=0.5-3mm for rough turning,
During precision machining, ap=0.05-0.2mm.
3) The diameter of the end face changes from the outside to the center, and the cutting speed also changes. When calculating the cutting speed, it must be calculated based on the maximum diameter of the end face.
4) When there is a concave or convex center on the end face with a larger diameter, the turning tool, square tool holder, and the large sliding plate should be checked for tightness. To ensure accurate lateral feed of the turning tool, the middle sliding plate should be fastened to the bed and the back cutting amount should be adjusted with a small tool holder.
5) When the end face quality requirements are high, the last cut should be cut from the center outward.
2. Quality analysis of vehicle end face
1) Uneven end face, resulting in convex and concave phenomena or leaving a "small head" in the center of the end face; The reason is that the installation of the turning tool is incorrect, the tool tip is not aligned with the center of the workpiece, the back cutting amount is too large, and there is a gap in the lathe caused by the movement of the sliding plate.
2) Poor surface roughness. The reason is that the turning tool is not sharp, the manual tool movement is uneven or too fast, and the automatic feed rate is not selected properly.
3, Internal hole turning
The characteristic of inner hole turning is that in a semi closed state, it is difficult to observe the chip removal situation, which affects the machining quality. Deep hole cutting often causes vibration of the tool holder, resulting in rapid wear of the cutting edge. Hard alloy tool holders are used for small diameter hole cutting, and vibration reducing tool holders are used for medium and above diameters.
When performing cylindrical turning, the length of the workpiece and the selected tool holder size do not affect the tool overhang, and therefore can withstand the cutting forces generated during machining. When boring and turning inner holes, the depth of the hole determines the overhang, so the aperture and length of the part have great limitations on the selection of cutting tools.
