The short stress rolling mill is a profile rolling mill with a short stress loop of the working machine. The stress loop of the working stand refers to the neutral line of the elastic deformation section of the stressed parts in the rolling mill after the rolling force is applied to the rolling mill. The length of the stress loop is the sum of the lengths of the stressed parts in the rolling mill. The elastic deformation produced by each stressed part in the rolling stand is directly proportional to its sectional area and inversely proportional to its length. The shorter the stress loop in the stand, the smaller the elastic deformation produced, the greater the stiffness of the rolling mill (see the stiffness coefficient of the rolling mill), and the higher the accuracy of the rolled products.

1. Two Ways to Shorten the Stress Return Line of the Rolling Mill
1.1 change the form of the bearing structure of the rolling mill, that is, reduce the number of bearing parts in the rolling mill stand. For example, the stress loop can be shortened by shortening the length of the stressed parts.

1.2 change the transmission path of the force, such as making the rolling force not directly act on the upper part of the housing window, but on the column close to the rolling mill, so as to shorten the stress loop.

The short stress line rolling mill is mainly used to transform the horizontal rolling mill, develop the double short stress line rolling mill (see the double short stress line finishing mill) and study the vertical short stress line rolling mill. It is built on the continuous rolling production line arranged at Pingyi interchange.

2. Advantages of Short Stress Line Mill
2.1 The high rigidity of the rolling mill ensures the high accuracy of the product, and it is easy to realize negative deviation rolling.

2.2 Symmetrical adjustment can be realized. This is of great significance to stabilize the operation, improve the operation rate, save the time for maintenance and replacement of the guide beam, reduce the operation accidents, avoid the process accidents such as bending, impact and winding of rolled pieces, and improve the service life of the guide.

2.3 Since the rolling mill has changed the transmission path of force and changed the concentrated load of the pressing screw into the distributed load distributed on both sides of the bearing pedestal, the bearing and bearing pedestal are better stressed, and the bearing life is increased by more than 1.5 times compared with the ordinary rolling mill, thus reducing the product cost.

2.4 The roll system of this type of rolling mill shall be pre-installed and adjusted before roll replacement, and the new roll system can be replaced about 10min after shutdown. And the adjusted new roll system can ensure that the products are qualified after rolling one or two pieces of steel. Therefore, the mill has good pre-adjusting performance, fast roll change and high yield.

A short stress line mill, also known as a housingless mill, is a kind of high rigidity mill. When used as a section steel mill, it should not only have high radial rigidity, but also have high axial rigidity. At present, many types of short stress line rolling mills have been developed in China, such as GY type, HB type, CW type, SY type, GW type and DW type. Among them, there are three representative types, namely, GY type short stress line rolling mill, Hb type no frame rolling mill and SY type high rigidity rolling mill. These rolling mills are self-developed with reference to the P-60 type no housing rolling mill in Sweden and in combination with their different conditions. Therefore, their main stress line structures are similar, except for some differences in the support mode and some specific structures, and each has its own characteristics.