The progress of wear-resistant plate leveling technology
In the process of hot and cold rolling of wear-resistant plates. Efforts to improve the shape of the plate are extensive. The main purpose in rolling is to make the wear-resistant plate reach a predetermined thickness and shape. At the same time to ensure the flatness of the wear plate. In the flattening process after rolling, the wear-resistant plate should meet the flatness requirements of the final use, and improve the performance and coating quality of the wear-resistant plate. Increase the yield and productivity of the formation process. In order to improve the flatness of the wear-resistant plate, different forms of leveling technology are applied to make the wear-resistant plate obtain a specific shape for further rolling.
In the rolling process. A series of plate defects may occur on the strip. There are three main forms, the first is the difference in surface area between the surface and the surface of the wear-resistant plate. Such as residual deformation after winding or sickle bending and lateral bending. The second is the difference in the length of the wear plate, such as edge waves (unilateral or bilateral waves), intermediate waves, longitudinal warping and distortion. The third defect is the difference in section thickness or bad section shape.
Stretch straightening and roll leveling can correct the first two defects. The last defect cannot be solved by leveling but should be solved in the rolling process. Uneven plate thickness can cause certain problems in longitudinal shear slitting, which will be discussed later. This paper looks at the application of stretch straightening and roll levelling, as well as some common and uncommon levelling methods, including the special case of non-sheet production.
Treatment of wear-resistant plate after rolling
After the steel strip is rolled. Several uncoiling, rewinding and heat treatment processes are required before final shipment. In these processes, stretch straightening and roll leveling are used many times. To change the shape of the wear plate.
After leaving the hot mill, carbon steel and stainless steel coils are usually acid-washed before further cold rolling. Secondary straightening is used in most modern pickling lines to improve the flatness of the wear plate, reduce warping and help break scales. Placing a puller straightener at the inlet of the pickling line can remove some iron scales and improve pickling efficiency. The improvement of flatness of wear-resistant plate in the process of acid washing can better open the plate and reduce the noise of strip steel. Reduced warping allows the strip to pass quickly through the pickling line without plate problems. When the tape is welded with a high-quality welding machine, the lead and tail parts of the poorly shaped steel can be straightened to the same quality as the main body of the steel coil. The iron scale powder can fall into the wet slag mud or the floating dust can be absorbed and removed by the ducted dust suction system.
Stretch straightener on finishing line
After cold rolling, the final thickness of the wear-resistant plate has reached, and the steel coil may have various plate shape defects, which has potential danger to the downstream process. Most modern high-yield treatment lines are fitted with tensioning equipment at the inlet end and operate at a constant speed range. The flatness of the steel strip at the end of the coating line should be selected to ensure that the distribution of the coating is uniform to prevent scratches or contact marks due to poor plate shape. Stretch straightening before coating is done to provide a flat substrate for uniform coating. Tension straightening, such as in the coating line, may damage the coating quality if a large amount of leveling is required.
The opportunity to check the flatness of the wear plate after flattening is limited in the high-speed continuous processing line, and this inspection is limited to the low-speed vertical processing line or the sample is cut at the outlet end of the processing line. On-line flatness check is affected by strip tension, and the cost is higher, which still needs to be studied. Empirical forecasting devices are becoming standardized, yielding repeatable results for the same raw materials.
Roller straightener
The working principle of roller straightening on the feed line, which is mostly used for final finishing and further processing, is that under zero tension, the wear-resistant plate is repeatedly bent, and the outer metal of the plate on the cross section of the steel strip produces a certain yield, forming a relatively flat product. The metal in the actinium plate does not yield, and this straightening method cannot make the whole wear-resistant plate produce fixed elongation. Certain areas of the width of the material bend at a smaller radius, allowing shorter or more taut parts to stretch. Elongation in these areas is limited to the outer metal of the steel strip, as opposed to stretching straightening. The end product can achieve a higher level of flatness. The resulting residual stress can be removed by further bending or shearing. Roller straightening can correct the first and second defects of the wear plate, but it cannot correct warping. Side warping and middle waves can be corrected by working rollers of different levels. By adjusting the vertical position of the support roll. Cause a set of rollers to be bent to a fixed shape at the top.
