Square tube forming method and square tube forming device

Abstract

To enhance forming performance enhanced in square tube forming of forming a round tube into a square tube by passing the round tube through a plurality of roll stands arranged in a raw tube forming direction. To give a high degree of multi-usability to a square tube forming device. To suppress the entire length of a roll stand array. A first flat roll stand 20A and a second flat roll stand 20B of rolling directions orthogonal to each other are arranged alternately in a forming direction to form a roll stand array 10. Each of the roll stands 20A and 20B includes roll gap adjusting means by which a rolling amount is independently settable, and one of the first flat roll stand 20A and the second flat roll stand 20B adjacent to each other is driven to rotate by roll driving means 40. A forming rolling amount distribution is allocated individually as a rolling amount at each of the roll stands 20A and 20B. The forming rolling amount distribution is determined in advance for stands from a first-stage stand to a final-stage stand in response to the outer diameter, thickness, and material of a forming target raw tube and an intended dimension of a square tube as a product.

1 . A square tube forming method of forming a round tube of any diameter as a forming target raw tube into a square tube of any dimension as a product by passing the round tube through a plurality of stages of roll stands arranged in a raw tube forming direction, comprising:
 using a flat roll stand array in which a first flat roll stand and a second flat roll stand of rolling directions orthogonal to each other are arranged alternately in a forming direction for a tube member and in which a rolling amount at each roll stand is independently settable;   allocating a forming rolling amount distribution individually as a rolling amount at each roll stand in the flat roll stand array, the forming rolling amount distribution being determined in advance for the stands from a first-stage stand to a final-stage stand in response to the outer diameter, thickness, and material of the forming target raw tube to be used and an intended dimension of the square tube as a product; and   forming into the square tube as a product having the intended dimension by rotationally driving two-direction roll in all the stages of at least one of the first flat roll stand and the second flat roll stand adjacent to each other to apply thrust to the forming target raw tube, and causing the forming target raw tube to be subjected to bending forming using two-direction rolls at each roll stand.   
     
     
         2 . The square tube forming method according to  claim 1 , wherein
 at one or a plurality of roll stands in a part of the flat roll stand array, thrust is applied to the tube member by forming an arc-like recess at a flat roll, the recess having a larger curvature than a roll contact surface R of the tube member to pass through the one or plurality of roll stands.   
     
     
         3 . The square tube forming method according to  claim 1 , wherein
 gap adjusting motors in a pair intended for the first flat roll stand and the second flat roll stand in a pair adjacent to each other are arranged to be movable along the flat roll stand array, and are shared between the first flat roll stands and the second flat roll stands in a plurality of pairs in the flat roll stand array.   
     
     
         4 .- 6 . (canceled)