Device and method for manufacturing hot-rolled sheet steel and device and method for sheet thickness pressing used for the device and method

A method for manufacturing a hot-rolled steel plate by plate thickness pressing, comprising the steps of:

• performing a thickness reduction process to a continuously cast slab having a plate thickness H to obtain a sheet bar in a roughing processing step;
• rolling said sheet bar to obtain a hot-rolled steel plate having a predetermined plate thickness in a finishing rolling processing step;
• and
• winding said hot-rolled steel plate after cooling in a winding step, wherein said roughing processing step at least partially includes processing said cast slab in a plate thickness press processing step using a pair of dies each of which has an inclined portion on an input side and a flat portion on an output side with a reduction ratio r in a plate thickness direction being not less than 30%, and a width reduction whose width reduction amount is equal to or above a width reduction amount determined by a function fn (r, H) applied to a material before said plate thickness press processing so that
• Width reduction amount=fn(r, H).

A manufacturing method for a hot-rolled steel plate by plate thickness pressing, comprising the steps of:

• processing a continuously cast slab by a plate thickness press process, wherein said press process has a reduction ratio in a plate thickness direction of not less than 0.5 and is applied to said continuously cast slab by using a pair of dies, each die having an inclined portion on an input side and a flat portion on an output side, and press process conditions are set within a range capable of satisfying the following inequalities represented by a contact length L of said inclined portion of each die and a material in a longitudinal direction, a feed amount f, a plate width W before processing, a volume V processed by said parallel portion of each die, a plate thickness h on said output side and a reduction strain ε;
• and
• applying continuous roughing rolling and subsequent finishing rolling to said slab after said press process to obtain a hot-rolled steel plate:
• εL/W<A
• Vε/(Wfh)<B
• where A and B are constants and A is not more than 0.6 and B is not more than 0.5.

A plate thickness pressing method for pressing a substantially rectangular material, comprising the steps of:

• pressing a substantially rectangular material in a widthwise direction to perform width adjustment;
• and
• subsequently applying plate thickness pressing in a plate thickness direction to said substantially rectangular material by using a die having a main processing surface consisting of at least an inclined portion on an input side and a parallel portion following said inclined portion with respect to said substantially rectangular material, wherein a non-steady width change amount ΔW and a non-steady length ΔL generated in at least one of a front end and a rear end of said substantially rectangular material by said plate thickness pressing are predicted by using the following expressions and said front end of said substantially rectangular material is preformed based on this prediction:
• ΔWH=f1(W,ε, Ldt), ΔWT=F2(W,ε, Ldt)
• ΔLH=g1(W, h, Ldt), ΔLT=g2(W, H, Ldt)
• where ΔWH is a predicted non-steady width change amount generated at said front end of said rectangular material in a moving direction by plate thickness pressing;
• ΔWT, a predicted non-steady width change amount generated at said rear end of said rectangular material in said moving direction by plate thickness pressing;
• ΔLH, a predicted non-steady length generated at said front end of said rectangular material in said moving direction by plate thickness pressing;
• ΔLT, a predicted non-steady length generated at said rear end of said rectangular material in said moving direction by plate thickness pressing;
• H, a plate thickness of said substantially rectangular material on a press input side;
• h, a plate thickness of said substantially rectangular material on a press output side;
• ε(=log(H/h)), a plate thickness strain;
• Ldt, a contact length of said material and said press die in a longitudinal direction;
• and W, a plate width of said substantially rectangular material.

A plate thickness pressing method for pressing a substantially rectangular material, comprising the steps of:

• preforming a substantially rectangular material by pressing in a widthwise direction to effect width adjustment to provide a distribution to a plate width of a steady portion of said substantially rectangular material in a width adjustment direction of plate thickness pressing;
• and
• subsequently applying plate thickness pressing to said substantially rectangular material in a plate thickness direction by using a die having a main processing surface consisting of at least an inclined portion on an input side and a parallel portion following said inclined portion with respect to said substantially rectangular material, wherein a steady portion plate width distribution amount dW generated by said plate thickness pressing and a pitch dL thereof are predicted by using the following expressions and said preforming are carried out based on this prediction:
• where, dW=F(V, W, h, f,ε)
• dL=G(H, h, f)
• H:
• a plate thickness of said substantially rectangular material on a press input side
• h:
• a plate thickness of said substantially rectangular material on a press output side
• ε(=log(H/h)):
• a plate thickness strain
• W:
• a plate width of said substantially rectangular material
• f:
• a feed amount of said substantially rectangular material at the time of plate thickness pressing
• V:
• a reduction volume of said parallel portion of said die.

A plate thickness pressing method for pressing a substantially rectangular material, comprising the steps of:

• preforming a substantially rectangular material by pressing in a widthwise direction to effect width adjustment;
• and
• subsequently applying plate thickness pressing to said substantially rectangular material in a plate thickness direction by using a die having a main processing surface consisting of at least an inclined portion on an input side and a parallel portion following said inclined portion with respect to said substantially rectangular material, wherein a non-steady width change amount ΔW and a non-steady length ΔL generated in at least one of a front end and a rear end of said substantially rectangular material by said plate thickness pressing and a width distribution dW of a steady portion and a pitch dL thereof are predicted by using the following expressions, said front end and said rear end of said substantially rectangular material are respectively preformed based on this prediction, and pre-forming for providing a plate width distribution of said steady portion of said substantially rectangular material is carried out:
• where ΔWH=f1(W, ε, Ldt), ΔWT=f2(W,ε,Ldt)
• ΔLH=g1(W, h, Ldt), ΔLT=g2(W, H, Ldt)
• dW=F(V, W, h, f,ε)
• dL=G(H, h, f)
• ΔWH is a predicted non-steady width change amount generated at said front end of said rectangular material in a moving direction by plate thickness pressing;
• ΔWT, a predicted non-steady width change amount generated at said rear end of said rectangular material in said moving direction by plate thickness pressing;
• ΔLH, a predicted non-steady length generated at said front end of said rectangular material in said moving direction by plate thickness pressing;
• ΔLT, a predicted non-steady length generated at said rear end of said rectangular material in said moving direction by plate thickness pressing;
• H, a plate thickness of said substantially rectangular material on a press input side;
• h, a plate thickness of said substantially rectangular material on a press output side;
• ε(=log(H/h)), a plate thickness strain;
• W, a plate width of said substantially rectangular material;
• f, a feed amount of said substantially rectangular material at the time of plate thickness pressing;
• V, a reduction volume of said parallel portion of said die;
• Ldt, a contact length of said substantially rectangular material and said press die in a longitudinal direction.

A plate thickness press apparatus comprising:

• a pair of dies, each die having a main processing surface consisting of at least an inclined portion on an input side and a parallel portion following said inclined portion with respect to a substantially rectangular material;
• means for feeding said substantially rectangular material to said pair of dies;
• a plate thickness pressing device for driving said pair of dies to press said substantially rectangular material in a plate thickness direction;
• and a vertical rolling mill which is provided on the pass line upstream side of said plate thickness pressing device and which operates to make small a gap change amount during processing and to form a sheet bar.

A plate thickness press apparatus comprising:

• a pair of dies, each die having a main processing surface consisting of at least an inclined portion on an input side and a parallel portion following said inclined portion with respect to a substantially rectangular material;
• means for feeding said substantially rectangular material to said pair of dies;
• a plate thickness pressing device for driving said pair of dies to press said substantially rectangular material in a plate thickness direction;
• and a widthwise direction pressing device which is provided on the pass line upstream side of said plate thickness pressing device and arranged at a position in tandem with said plate thickness pressing device, wherein said widthwise direction pressing device consists of a vertical rolling mill capable of changing an opening during processing.

A hot rolled slab forming method, comprising the steps of:

• providing a width reduction press on the downstream side of a thickness reduction press;
• subjecting a continuously cast hot slab to thickness reduction by said thickness reduction press;
• and
• then subjecting said slab to width reduction by said width reduction press after releasing said thickness reduction press.

A plate thickness pressing method for forging a hot slab, comprising the steps of:

• providing a hot slab;
• and
• forging said hot slab by bringing said hot slab into contact with a die having a main processing surface consisting of a tapered portion inclined in an input side direction at a taper angle of 10 to 30 degrees relative to a moving direction of said hot slab and a parallel portion which follows said tapered portion and is parallel to said moving direction,
• wherein a contact start surface of said hot slab and said die is a transition area between said tapered portion and said parallel portion and a part of said parallel portion, and provides a reduction amount of 50 mm, 100 mm, and 150 mm when a feed amount for said hot slab respectively ranges between 50-145 mm, 100-275 mm, and 150-425 mm.