1. Surface before processing
Since rolling is a processing method using roller rolling, the surface roughness after processing is affected by the height and shape of the raised part (that is, the state before processing).
If the surface is rough before processing (high convex part and deep concave part), the convex part cannot be completely buried in the concave part, resulting in rough surface.
In addition, the shape of the raised portion also affects the processed surface. When the regular concave-convex shape is cut by a lathe or a boring sheet, and the height is easy to roll, an ideal surface can be obtained. Generally, the better the surface condition before processing, the better the surface condition after processing, and the wear of the rolling head is also less. If necessary, a process can be added.
2. Dimensions before processing
Since rolling is a processing method using rollers, the diameter of the workpiece before and after processing will change (the inner diameter will be enlarged, and the outer diameter will be reduced). In order to be able to process to within the dimensional tolerance range, this change should be considered to determine the size of the previous process. The amount of change in diameter is related to the material, hardness, and rolling amount of the workpiece, so Z initially determines its size after 2 to 3 trial machining.
3. Drive machinery
The standard model of rolling head has Morse taper mounting part and parallel mounting part. Rolling processing is different from cutting processing. It does not require high torque and can also be used on low-power machine tools. It can be installed on drilling machines, lathes, hexagonal lathes, boring machines, drills and other equipment for processing without special equipment. ?
4. Lubrication and cleaning
Since the rolling process is processed by roller rolling, fine dust will be generated. Dust not only affects the surface quality, but also accelerates the wear of the rolling head, so it is necessary to inject a large amount of cutting fluid to remove the dust. The cutting fluid with low viscosity should be used when rolling. Although cutting fluid with high viscosity has good lubricity, it has poor cleaning performance and is not suitable for rolling processing. The company has special rolling lubricants for rolling processing. As long as 5% of the rolling lubricants are mixed with low-viscosity cutting fluids, its outstanding performance can be exerted.
5. The wall thickness of the processed part
Rolling is to use rollers to roll the surface of the processed part to densify it. Therefore, in order to be able to withstand the processing pressure, the part to be processed should have a sufficient wall thickness (20% of the inner diameter). When the wall thickness is too thin or partly thin, undulations or decrease in roundness will occur after processing.
This problem is usually solved by the following methods: ①Reduce the amount of rolling; ②Use a clamp to support the outer periphery; ③To implement rolling processing before thinning the wall thickness.
6. Hardness of the processed part
The upper limit of the hardness of the workpiece that can be processed by the rolling head is 40HRC, but the rolling head is also specially designed for processing high-hardness workpieces (the upper limit of hardness is 55HRC). When rolling high-hardness workpieces, the machining part is subjected to high pressure and the tool life is shortened. Therefore, in order to obtain the required precision of the machined surface, the main measure is to reduce the amount of rolling.
7. Speed and feed
Rotate the rolling head to the right for rolling processing; the rolling head can also be fixed, and the same result can be obtained by rotating the workpiece. The speed and feed rate vary according to the machining diameter.
8. The part that cannot be rolled
When rolling blind holes and stepped shafts with a rolling head, there are the following parts that cannot be processed: ①The arc part of the front end of the roller; ②The distance from the front end of the roller to the front end of the bracket; ③The gap between the front end of the bracket and the end surface of the processed part ; In order to make the part Z that cannot be processed by rolling be small, after the tool diameter is set, the mandrel at the front end of the roller shall be ground off or the protrusion of the head shall be kept at the same position as the front end of the roller.