During the processing of the parts, a certain degree of roughness will be formed on the surface of the parts, which is very unfavorable to the normal use of the parts. The factors that affect the surface roughness of parts include the influence of tool geometry, the influence of accumulated cutting edges, the influence of workpiece material, the influence of processing conditions, and the influence of vibration. The following will describe the factors that affect the surface roughness of parts.
1. The influence of tool geometry
A tool is a tool used to cut parts. During the cutting process, the contact between the tool and the part is the most sufficient, so the tool has the greatest impact on the surface roughness of the part. Appropriately increasing the rake angle of the tool geometry can reduce it to a greater extent. Surface roughness of small parts, but excessively increasing the rake angle of the tool geometry will increase the surface roughness. This is difficult to control in the actual process, and easily causes the surface roughness of the parts to be greatly affected. When the front angle is constant, the larger the back angle, the sharper the cutter and easier cutting. Properly increasing the relief angle can reduce the friction and extrusion between the blade face and the surface of the part, so that the surface friction of the part can be effectively reduced.
But when the clearance angle is too large, cutting vibration will occur, which will increase the surface friction of the part. However, the proper clearance angle is also difficult to grasp in actual operation, so it is easy to increase the surface roughness of the part in actual operation. In addition, the surface roughness of the tool's rake face and flank face also has a certain influence. If the roughness of the tool's rake face and flank face is smaller, the surface roughness of the part will be smaller. Because the smoother the front and rear surfaces of the tool, the sharper it is, and it is not easy to produce gaps during the cutting process, which reduces the surface roughness of the parts. It can be seen that the geometry of the tool has a very important influence on the surface roughness of the parts, so the medicine focuses on this influence factor in the process of reducing the surface roughness of the parts.
2. The impact of accumulated tumor
An accumulated tumor refers to that during the metal cutting process, some metal falling from the workpiece will be cold-welded and layered on the rake face. This will form a very hard metal deposit, this metal deposit Its hardness is 2 to 3 times that of the workpiece, which can replace the cutting edge for cutting, but it will gradually fall off during the continuous cutting process. This metal deposit refers to the built-up edge. The shape of the built-up tumor is irregular, and its size may change with the cutting of the workpiece so that the surface roughness of the part will increase during the cutting process of the workpiece, and the accumulation of the built-up tumor will fall extremely during the process. It may adhere to the surface of the workpiece, so that the surface roughness of the part will increase significantly, thereby affecting the performance of the part.
3. The influence of workpiece material
In the process of cutting the workpiece, its surface roughness has a great influence on its material. Some workpiece materials are not suitable for cutting, so serious damage is likely to occur during the cutting process, and the surface roughness of the workpiece is even more unobtainable. Effective control will greatly reduce the performance of the workpiece. In addition, thermal processing will be carried out during the cutting process of the workpiece, so that the quality of the workpiece will be better and the service life of the workpiece will be longer.
4. The influence of processing conditions
In the cutting process of the workpiece, the processing conditions also have a greater impact on the surface roughness. The first is the cutting speed. Generally, the cutting speed is prone to buildup in the medium speed section, so the medium speed section should be avoided during the processing. It is necessary to increase or decrease the cutting speed reasonably according to the actual situation. In addition, in order to reduce the surface roughness of the workpiece, the sharpness of the tool can be increased, so that the tool is smoother during the cutting of the workpiece. Cooling lubricating fluid is also used in the process of workpiece processing. The main function of cooling lubricating fluid is to reduce the friction between the tool and the chips, thereby reducing the friction between the tool and the processing surface, and making the surface roughness of the workpiece smaller.
5. The effect of vibration
The vibration will also occur during machining, which is mainly due to the periodic displacement of the tool to the workpiece during the cutting process so that traces similar to ripples will be formed on the surface of the workpiece. In addition, there will be a certain amount of vibration inside the machine tool during the cutting of the workpiece, which will make the cutting process of the workpiece unbalanced, and its manifestation is that the surface friction of the processed workpiece increases.