09-01-2017· Before dual motor drives, rolls had to be ground the same diameter. If one roll needs to be ground, the opposing roll must be ground at the same diameter. Four-high mills are very common for steel, aluminum, copper, and any high production metal rolling. One disadvantage of a 4-high mill
24-12-2018· As per the requirement of the process and arrangement of the rolls, the rolling mill rolls can be divided into the following categories: 1.Two High Rolling Mills It consists of two rollers, which rotate in the opposite direction for the desired movement of 2.Three High Rolling Mills
A four high rolling mill is used for reducing material to minute thicknesses. Through the use of backup rolls, the issues of roll deflection can be avoided and smaller work rolls can be used. The reduction in work roll diameter reduces overall separating force required
Section rolling mills 1,6-2,5; Plate mills 2,0-2,8; 4-hi mills a) 3-5 (for work rolls); b) 0,9-2,5 (for back up rolls). Roll neck length usually equals to roll diameter. Diameter of roll necks with antifriction and friction (close type) bearings shall be in accordance with design.
The diameter of the 4-high work rolls amounts to approximately 1:4 in relation to the barrel length. This type of rolling mill is mainly used in offline applications for cold rolling of soft and medium strip and for a wide range of strip widths, as well as for break-down rolling in offline applications.
24-12-2018· As per the requirement of the process and arrangement of the rolls, the rolling mill rolls can be divided into the following categories: 1.Two High Rolling Mills It consists of two rollers, which rotate in the opposite direction for the desired movement of 2.Three High Rolling Mills The Three
A four high rolling mill is used for reducing material to minute thicknesses. Through the use of backup rolls, the issues of roll deflection can be avoided and smaller work rolls can be used. The reduction in work roll diameter reduces overall separating force required for reductions; reduces the overall energy needed for reducing the material and produces more consistent thickness output.
As the name suggests the 4 Hi mill employs 4 rolls, two these are the work rolls and the other two are the backup rolls. The rolls between which the cold rolling actually takes lace is called the work roll. The OD of the work rolls is between 208 to 225 mm or 145 to 155 mm, while the backup roll may be 575 to 610 mm.
3. Four High Rolling Mills: In this type of mill, there are four parallel rolls one by another. In this operation, the rotation of the first and the fourth rolls take place in the opposite direction of the second and the third rolls. The second and third rolls are smaller to provide rigidity in necessity. So those are known as back up rolls.
Tandem rolling is also known as continuous rolling in which two or more set of four high rolling mill arranged in a series in which each set is called stand. These stands are arranged so they can roll the work piece in decreasing cross section. It is used for rolling thick work piece in single pass.
The four-high rolling mill consists of four rollers, two of which are working rollers (small diameter) and the other two are backing up rollers (larger diameter). The all four rollers are arranged above one another in a vertical plane. Also, the backup rollers always have larger diameters than those of the working rollers.
Good figures for rod and bar mills are 90 % to 93 %, for structural mills, the good mill utilization figures are 75 % to 78 %. If a mill rolls 80 % of the calendar year, that is 365 x 24 x 0.80 = 7008 hours. If the mill rolls 800,000 tons per year, it runs at an average production rate of 114.16 tons/hour.
The industrial application verified the new taper roll shifting strategy, as both the edge drop and high spots were alleviated and the rolling length of a schedule was extended by about 10 km.
iv) Tendem or Continuous rolling Mill :-It consists of a number of non reversing two-high rolling mills arrange one after other. So that the material can be passed through all of them in sequence.It is suitable for mass production work only, because for smaller quantities quick changes of set upwill be required and they will consume lot of labor and work.