Rolling mill, hot rolling system, rolling method and rolling mill revamping method

A rolling mill in which a pair of work rolls and a pair of back-up rolls for respectively supporting the work rolls are provided as work roll and back-up roll combinations on a rolling stand, wherein the back-up rolls are constructed in such a manner that axes thereof are not inclined in a horizontal plane while the work rolls are constructed in such a manner that axes thereof can be inclined in a horizontal plane relative to the back-up rolls such that the axes of the work rolls cross the axes of the back-up rolls and such that the axes of the work rolls cross each other, wherein a lubricant supply device is provided for supplying a lubricant between the work roll and the back-up roll of each combination, and wherein a system is provided for controlling an angle at which said work rolls cross each other, said cross angle controlling system including thrust force detectors for detecting thrust forces acting on said back-up rolls and on said work rolls, cross-angle controlling devices for setting and controlling the work roll cross angle, said lubricant supply device including a lubricant header through which lubricant can be sprayed to effect lubrication between the work roll and the back-up roll of each combination, said cross angle controlling system further including lubricant flow rate detector apparatus for detecting rate of flow of the lubricant through said lubricant supply device, devices for detecting and controlling the pressure at which the lubricant is sprayed through said lubricant header, said thrust force detectors being operative to generate a signal either when the thrust force acting on at least one of said back-up rolls exceeds an allowable maximum magnitude determined based on supporting machine structure or when the thrust force acting on at least one of said work rolls exceeds an allowable maximum magnitude determined based on the supporting machine structure, said cross angle controlling system further including a controller responsive to the signal from said thrust force detectors to warn an operator and control said cross-angle controlling system such that the work roll cross angle is reduced.

A hot rolling system of the type that has a rough rolling mill and a finish rolling mill, wherein a rolling mill is provided in an upstream stage of said finish rolling mill and comprises a pair of work rolls and a pair of back-up rolls for respectively supporting the work rolls, said work rolls being arranged such that their axes can be inclined in a horizontal plane such that a rolling of a material to be rolled is carried out with the axes of said work rolls crossing each other, wherein:

• said back-up rolls are arranged such that the axes of said back-up rolls are disposed in a horizontal plane and fixed in a direction substantially perpendicular to a direction of rolling of said material;
• said work rolls are supported such that respective angles of inclination of respective work rolls are controllable so that the axes of said work rolls cross the axes of said back-up rolls and also cross a line perpendicular to the direction of rolling of said material;
• said work rolls and said back-up rolls are arranged such that a first thrust force acts from each back-up roll to an associated work roll in a direction opposite to a direction in which a second thrust force acts from said material to the work roll so that an actual thrust force acting on the work roll is equal to a difference between said first and second thrust forces;
• and
• a lubricant supply device is provided for supplying an axial thrust reducing lubricant to a zone between each work roll having its axis crossing the axis of an associated back-up roll and the back-up roll with which said work roll is in direct contact, to thereby maintain axial thrust reducing lubrication in said zone, whereby the actual thrust force is reduced by the lubrication in said zone between the work roll and the back-up roll.

A method of revamping a 4-high rolling mill of the type that has a pair of rolling stands, a pair of work rolls and a pair of back-up rolls respectively supporting said work rolls, said method comprising the steps of:

• providing roll displacing means on at least one of said rolling stands so that said roll displacing means displaces said work rolls such that their axes are inclined in a horizontal plane and such that the angles of inclination of respective work rolls are controlled so that the axes of said work rolls cross each other and cross respective axes of respective ones of the back-up rolls;
• arranging said back-up rolls such that the axes of said back-up rolls are disposed in a horizontal plane and fixed in a direction substantially perpendicular to a direction of rolling of said material;
• supporting said work rolls such that respective angles of inclination of respective work rolls are controllable so that the axes of said work rolls cross the axes of said back-up rolls and also cross a line perpendicular to the direction of rolling of said material;
• arranging said work rolls and said back-up rolls such that a first thrust force acts from each back-up roll to an associated work roll in a direction opposite to a direction in which a second thrust force acts from said material to the work roll so that an actual thrust force acting on the work roll is equal to a difference between said first and second thrust forces;
• and
• providing a lubricant supply device for supplying an axial thrust reducing lubricant to a zone between each work roll having its axis crossing the axis of an associated back-up roll and the back-up roll with which said work roll is in direct contact, to thereby maintain axial thrust reducing lubrication in said zone, whereby the actual thrust force is reduced by the lubrication in said zone between the work roll and the back-up roll, whereby said rolling mill is revamped into a type in which the work rolls can be inclined and be operated without excessive axial thrust forces on said work rolls.

A method of controlling a rolling mill of the type that has a pair of work rolls and a pair of back-up rolls for respectively supporting the work rolls being provided on a rolling stand, said work rolls being arranged such that their axes can be inclined in a horizontal plane such that a rolling of a material to be rolled is carried out with the axes of said work rolls crossing each other, said back-up rolls being arranged such that the axes of said back-up rolls are disposed in a horizontal plane and fixed in a direction substantially perpendicular to a direction of rolling of said material, said work rolls being supported such that respective angles of inclination of respective work rolls are controllable so that the axes of said work rolls cross the axes of said back-up rolls and also cross a line perpendicular to the direction of rolling of said material, said work rolls and said back-up rolls being arranged such that a first thrust force acts from each back-up roll to an associated work roll in a direction opposite to a direction in which a second thrust force acts from said material to the work roll so that an actual thrust force acting on the work roll is equal to a difference between said first and second thrust forces, and a lubricant supply device is provided for supplying an axial thrust reducing lubricant to a zone between each work roll having its axis crossing the axis of an associated back-up roll and the back-up roll with which said work roll is in direct contact, to thereby maintain axial thrust reducing lubrication in said zone, whereby the actual thrust force is reduced by the lubrication in said zone between the work roll and the back-up roll, said method comprising the steps of:

• controlling the respective angles of inclination of said work rolls in accordance with a rolling condition in a rolling of a material such that the respective angles of inclination of said work rolls are changed during the rolling operation;
• and
• controlling the supply of said lubricant in accordance with the rolling condition.

A rolling mill comprising:

• a pair of work rolls;
• a pair of back-up rolls for supporting the work rolls, with said back-up rolls being provided as work roll and back-up roll combinations on a rolling stand, axes of the back-up rolls not being inclined in a horizontal plane and axes of the work rolls being configured and supported to be inclined in a horizontal plane relative to the back up rolls such that the axes of the work rolls cross the axes of the back-up rolls and such that the axes of the work rolls cross each other;
• a lubricant supply device for supplying a lubricant between the work roll and back-up roll of each combination;
• and
• a controller configured to vary the amount and type of supplied lubricant as a function of a respective angle between an axis of a work roll and a line perpendicular to a direction of rolling.

A rolling mill comprising:

• a pair of work rolls which each have a rotational work roll axis,
• a pair of back-up rolls for respectively supporting the work rolls, said back-up rolls each having a rotational back-up roll axis,
• said work rolls being supported during rolling operations with their respective rotational work roll axes crossed with respect to one another and crossed with respect to respective associated back-up roll axes, said work rolls and said back-up rolls being arranged such that a first thrust force acts from each back-up roll to an associated work roll in a direction opposite to a direction in which a second thrust force acts from said material to the work roll so that an actual thrust force acting on the work roll is equal to a difference between said first and second thrust forces;
• and
• a lubricant supply device is provided for supplying an axial thrust reducing lubricant to a zone between each work roll having its axis crossing the axis of an associated back-up roll and the back-up roll with which said work roll is in direct contact, to thereby maintain axial thrust reducing lubrication in said zone, whereby the actual thrust force is reduced by the lubrication in said zone between the work roll and the back-up roll.

A method of rolling a strip of material in a rolling mill of the type comprising:

• a pair of work rolls which each have a rotational work roll axis,
• a pair of back-up rolls for respectively supporting the work rolls, said back-up rolls each having a rotational back-up roll axis,
• said work rolls being supported during rolling operations with their respective rotational work roll axes crossed with respect to one another and crossed with respect to respective associated back-up roll axes, said work rolls and said back-up rolls being arranged such that a first thrust force acts from each back-up roll to an associated work roll in a direction opposite to a direction in which a second thrust force acts from said material to the work roll so that an actual thrust force acting on the work roll is equal to a difference between said first and second thrust forces;
• and
• a lubricant supply device being provided for supplying an axial thrust reducing lubricant to a zone between each work roll having its axis crossing the axis of an associated back-up roll and the back-up roll with which said work roll is in direct contact, to thereby maintain axial thrust reducing lubrication in said zone, whereby the actual thrust force is reduced by the lubrication in said zone between the work roll and the back-up roll
• said method comprising:
• operating said rolling mill by pressing said work rolls against said strip of material with a rolling pressure,
• and supplying axial thrust reducing lubricant between said respective back-up rolls and work rolls to thereby assure maintenance of said resultant axial thrust forces acting on the work rolls at a value less than a predetermined percentage of the rolling pressure exerted on the material being rolled during rolling operations.

A rolling mill stand comprising:

• a pair of work rolls;
• a pair of back-up rolls for supporting the work rolls, axes of the back-up rolls not being adjustably inclined in a horizontal plane and axes of the work rolls being configured and supported to be adjustably inclined in a horizontal plane relative to the back-up rolls such that the axes of the work rolls cross the axes of the back-up rolls and such that the axes of the work rolls cross each other, said work rolls and said back-up rolls being arranged such that a first thrust force acts from each back-up roll to an associated work roll in a direction opposite to a direction in which a second thrust force acts from said material to the work roll so that an actual thrust force acting on the work roll is equal to a difference between said first and second thrust forces;
• and
• a lubricant supply device is provided for supplying an axial thrust reducing lubricant to a zone between each work roll having its axis crossing the axis of an associated back-up roll and the back-up roll with which said work roll is in direct contact, to thereby maintain axial thrust reducing lubrication in said zone, whereby the actual thrust force is reduced by the lubrication in said zone between the work roll and the back-up roll.

A rolling mill in which a pair of work rolls and a pair of back-up rolls for respectively supporting the work rolls are provided on a rolling stand and said work rolls are arranged such that their axes can be adjustably inclined in a horizontal plane such that a rolling of a material to be rolled is carried out with the axes of said work rolls crossing each other;

• wherein said work rolls are supported such that respective angles of inclination of respective work rolls are controllable so that the axes of said work rolls cross the axes of said back-up rolls and also cross a line perpendicular to the direction of rolling of said material;
• wherein said work rolls and said back-up rolls are arranged such that a first thrust force acts from each back-up roll to an associated work roll in a direction opposite to the direction in which a second thrust force acts from said material to the work roll so that an actual thrust force acting on the work roll is equal to a difference between said first and second thrust forces;
• and
• a lubricant supply device is provided for supplying an axial thrust reducing lubricant to a zone between each work roll having its axis crossing the axis of an associated back-up roll and the back-up roll with which said work roll is in direct contact, to thereby maintain axial thrust reducing lubrication in said zone, whereby the actual thrust force is reduced by the lubrication in said zone between the work roll and the back-up roll.

A method of making rolled strip material comprising:

• providing strip material,
• rolling said strip material in a rolling mill stand having a pair of work rolls and back-up rolls supporting the work rolls,
• said rolling includes adjustably inclining axes of the work rolls with respect to one another and with respect to axes of said back-up rolls to thereby control crown of the strip material being rolled,
• wherein said work rolls and said back-up rolls are arranged such that a first thrust force acts from each back-up roll to an associated work roll in a direction opposite to the direction in which a second thrust force acts from said material to the work roll so that an actual thrust force acting on the work roll is equal to a difference between said first and second thrust forces, and
• supplying an axial thrust reducing lubricant to a zone between each work roll having its axis crossing the axis of an associated back-up roll and the back-up roll with which said work roll is in direct contact, to thereby maintain axial thrust reducing lubrication in said zone, whereby the actual thrust force is reduced by the lubrication in said zone between the work roll and the back-up roll.

A rolling mill stand comprising:

• a first work roll rotatable about a first work roll axis,
• a second work roll rotatable about a second work roll axis,
• said first and second work rolls being engageable with respective opposite sides of a material strip to roll said material strip during rolling operations with said material strip traveling between the work rolls,
• a first back-up roll rotatable about a first back-up roll axis and supportingly engageable with said first work roll at a side of said second work roll opposite the material strip being rolled,
• a second back-up roll rotatable about a second back-up roll axis and supportingly engageable with said second work roll at a side of said second work roll opposite the material strip being rolled,
• said first and second work rolls being supported to be adjustably inclined with respect to one another and to the first and second back-up rolls during rolling operations such that radial planes through the respective first and second work roll axes cross each other and cross respective radial planes through the respective first and second back-up roll axes, whereby each of said work rolls experiences an actual axial thrust force equal to a difference between axial thrust forces in one axial direction from the material strip being rolled and in an opposite axial direction from a respective associated back-up roll,
• an axial thrust force reducing lubricant supplied to a zone between each work roll having its axis crossing the axis of an associated back-up roll and the back-up roll with which said work roll is in direct contact, to thereby maintain axial thrust reducing lubrication in said zone, whereby the actual thrust force is reduced by the lubrication in said zone between the work roll and the back-up roll, and
• a further lubricant having a different composition than the axial thrust reducing lubricant between the work rolls and the material strip being rolled,
• whereby the axial thrust force reducing lubricant reduces the actual axial thrust forces on said work rolls facilitating rolling operations with said adjustably inclined work rolls.