Analysis: 8 major requirements for workpiece technology before rolling

Since rolling processing is a processing method that uses roller rolling, the surface roughness after processing is affected by the height and shape of the protrusions (that is, the state before processing)

1. Appearance before processing

Because rolling processing is a processing method using roller rolling, the surface roughness after processing is affected by the height and shape of the protrusions (that is, the state before processing).

If the surface condition is rough before processing (the convex part is high and the concave part is deep), the convex part cannot be completely buried in the concave part, resulting in a rough surface.

In addition, the shape of the raised part also affects the appearance after processing. When the regular concave-convex shape is cut by a lathe or a boring sheet, and the height is easy to roll, the most ideal appearance can be obtained. The better the appearance before ordinary processing, the better the appearance after processing, and the wear of the rolling head is also less. If required, a process can be added.

2. Dimensions before processing

Because rolling processing is a processing method that uses roller rolling, the diameter of the workpiece will change before and after processing (the inner diameter will expand, and the outer diameter will decrease). In order to be able to process to the size tolerance range, the size of the previous process should be determined by considering this amount of change. The amount of change in diameter is related to the material, hardness, and rolling amount of the workpiece, so the size is determined after the initial stop of 2 to 3 trial machining.

3. Drive machinery

The standard models of the rolling head include 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 with low-power machine tools. It can be installed on drilling machines, lathes, hexagonal lathes, boring machines, drills and other equipment to stop processing without special equipment.

4. Smooth and clean

Because the rolling process uses roller rolling to stop the process, fine dust will be generated. Dust not only affects the appearance 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. High-viscosity cutting fluids have good smoothness, but poor cleaning performance and are not suitable for rolling.

5. Processing local wall thickness

Rolling processing is the use of rollers to process the local surface to make it dense. Therefore, in order to be able to accept the processing pressure, the part to be processed should have sufficient wall thickness (20% of the inner diameter). When the wall thickness is too thin or the part is thin, the undulation or roundness will occur after processing.

Usually the following methods are used to deal with this problem: ①Reduce the amount of rolling; ②Use fixtures to support the outer circumference; ③Use rolling processing before thinning the wall thickness.

6. Hardness of processed parts

The upper limit of 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 processing high-hardness workpieces, the tool life is shortened due to the high pressure in the processing part. Therefore, in order to obtain the required precision of the machined surface, the main measure is to reduce the amount of rolling.

7. Speed u200bu200band feed

Rotate the rolling head to the right to stop rolling processing; the rolling head can also be fixed, and the same result can be obtained by rotating the workpiece. Rotation speed and feed speed vary according to the machining diameter.

8. The part that cannot be rolled

When using the rolling head to stop the rolling processing of blind holes and stepped shafts, there are the following parts that cannot be processed: ①The arc part of the front end of the roller; ②The interval between the front end of the roller and the front end of the bracket; ③The front end of the bracket to the processing part The gap in the end surface; in order to minimize the part where the rolling process cannot be stopped, after the tool diameter is determined, the mandrel at the front end of the roller will be ground off or the protrusion of the head will be kept at the same position as the front end of the roller.