Screen bar, bar screen and method for producing a screen bar

Patent metadata

Field	Value
Publication number	US-2016368024-A1
Application number	US-201414900316-A
Country	US
Kind code	A1
Filing date	Jun 13, 2014
Priority date	Jun 24, 2013
Publication date	Dec 22, 2016
Grant date	—

Abstract

A screen bar for a bar screen may comprise a steel composite sheet having at least three steel layers: a top layer, a core layer, and a bottom layer. The top, core, and bottom steel layers may be interconnected by roll cladding in a non-releasable manner. In some examples, the core steel layer may have a higher deformability than the top steel layer and the bottom steel layer. Likewise, the top steel layer and the bottom steel layer may have higher hardnesses than the core steel layer. Such screen bars have extended service life and can be manufactured more cost effectively, amongst other benefits. Methods for manufacturing such screen bars may involve a variety of steps including hot rolling and/or heat-treating.

First claim

1 .- 10 . (canceled)

11 . A screen bar for a bar screen, the screen bar comprising:
a steel composite sheet comprising a top steel layer, a core steel layer, and a bottom steel layer, wherein the top steel layer, the core steel layer, and the bottom steel layer are non-releasably interconnected by roll cladding, wherein the core steel layer has a higher deformability than the top steel layer and the bottom steel layer, wherein the top steel layer and the bottom steel layer have higher hardnesses than the core steel layer.

12 . The screen bar of claim 11 wherein a thickness of the core steel layer is at least 40 percent of a total thickness of the steel composite sheet.

13 . The screen bar of claim 11 wherein the core steel layer comprises at least two layers that are positioned adjacent to one another and are interconnected by roll cladding.

14 . The screen bar of claim 11 wherein the top steel layer and the bottom steel layer consist of martensitic steel.

15 . The screen bar of claim 14 wherein a hardness of the top steel layer and a hardness of the bottom steel layer exceed 500 HBW.

16 . The screen bar of claim 14 wherein a composition of the top and bottom steel layers contains iron, impurities, and in percentage by weight 0.35-0.45% C, 0.15-0.30% Si, 0.75-0.95% Mn, 0.07-0.1% Al, 0.8-0.95% Cr, 0.017-0.028% Nb, 0.15-0.28% Mo, 1.1-1.3% Ni, 0.0015-0.0035% B, and 0.0007-0.0030% Ca.

17 . The screen bar of claim 11 wherein a hardness of the core steel layer is 350-500 HBW.

18 . The screen bar of claim 11 wherein a composition of the core steel layer contains iron, impurities, and in percentage by weight 0.16-0.22% C, 0.15-0.40% Si, 0.90-1.45% Mn, 0.02-0.1 Al, 0.45-1.05% Cr, up to 0.033% Nb, up to 0.65% Mo, up to 2.0% Ni, up to 0.0035% B, and 0.0007-0.0030% Ca.

19 . A bar screen having at least one screen bar according to claim 11 .

20 . A method for manufacturing the screen bar according to claim 11 , the method comprising:
providing a first hot-rolled steel plate that forms the core steel layer of the steel composite sheet; providing two hot-rolled steel plates that form the top steel layer and the bottom steel layer of the steel composite sheet; positioning the steel plates into a stack such that the core steel layer is placed above the bottom steel layer and such that the top steel layer is placed above the core steel layer; connecting the bottom steel layer, the core steel layer, and the top steel layer of the stack in a fixed non-releasable manner; heating the stack to an initial temperature for hot rolling; hot rolling the stack; and cutting the screen bar from the stack.

21 . The method for manufacturing the screen bar according to claim 20 , the method further comprising cleaning and straightening faces of the steel plates.

22 . The method for manufacturing the screen bar according to claim 20 , the method further comprising:
hot rolling the stack by reheating the stack to the initial temperature between any sub-steps of the hot rolling step; heat-treating the stack, wherein the heat-treating comprises:
heating the stack to a temperature that is above a highest of Ac3 temperatures for steel types corresponding to the bottom steel layer, the core steel layer, and the top steel layer;
quenching the stack at a rate sufficient to generate hardened structures in the bottom and top steel layers of the stack; and
tempering the quenched stack.

23 . The method for manufacturing the screen bar according to claim 20 , the method further comprising post-machining the screen bar cut from the stack.

24 . A method for manufacturing the screen bar according to claim 11 , the method comprising:
providing a first hot-rolled steel plate that forms the core steel layer of the steel composite sheet; providing two hot-rolled steel plates that form the top steel layer and the bottom steel layer of the steel composite sheet; cleaning and straightening faces of the steel plates; positioning the steel plates into a stack such that the core steel layer is placed above the bottom steel layer and such that the top steel layer is placed above the core steel layer; connecting the bottom steel layer, the core steel layer, and the top steel layer of the stack in a fixed non-releasable manner; heating the stack to an initial temperature for hot rolling; hot rolling the stack, wherein the stack is reheated to the initial temperature between any sub-steps of the hot rolling step; heat-treating the stack, wherein the heat-treating comprises:
heating the stack to a temperature that is above a highest of Ac3 temperatures for steel types corresponding to the bottom steel layer, the core steel layer, and the top steel layer;
quenching the stack at a rate sufficient to generate hardened structures in the bottom and top steel layers of the stack; and
tempering the quenched stack;
cutting the screen bar from the stack; and post-machining the screen bar cut from the stack.

25 . A method for manufacturing a screen bar, the method comprising:
providing a first hot-rolled steel plate as a core steel layer; providing two hot-rolled steel plates that form a top steel layer and a bottom steel layer; positioning the steel plates into a stack such that the core steel layer is placed above the bottom steel layer and such that the top steel layer is placed above the core steel layer; connecting the bottom steel layer, the core steel layer, and the top steel layer of the stack in a fixed non-releasable manner; heating the stack to an initial temperature for hot rolling; hot rolling the stack to form a steel composite sheet; and cutting the screen bar from the steel composite sheet.

26 . The method for manufacturing the screen bar according to claim 25 further comprising cleaning and straightening faces of the steel plates before positioning the steel plates into the stack.

27 . The method for manufacturing the screen bar according to claim 25 , the method further comprising:
hot rolling the stack to form the steel composite sheet by reheating the stack to the initial temperature between any sub-steps of the hot rolling step; heat-treating the stack, wherein the heat-treating comprises:
heating the stack to a temperature that is above a highest of Ac3 temperatures for steel types corresponding to the bottom steel layer, the core steel layer, and the top steel layer;
quenching the stack at a rate sufficient to generate hardened structures in the bottom and top steel layers of the stack; and
tempering the quenched stack.

28 . The method for manufacturing the screen bar according to claim 25 , the method further comprising post-machining the screen bar cut from the steel composite sheet.

29 . A method for manufacturing a screen bar, the method comprising:
providing a first hot-rolled steel plate as a core steel layer; providing two hot-rolled steel plates as a top steel layer and a bottom steel layer; cleaning and straightening faces of the steel plates; positioning the steel plates into a stack such that the core steel layer is placed above the bottom steel layer and such that the top steel layer is placed above the core steel layer; connecting the bottom steel layer, the core steel layer, and the top steel layer of the stack in a fixed non-releasable manner; heating the stack to an initial temperature for hot rolling; hot rolling the stack, wherein the stack is reheated to the initial temperature between any sub-steps of the hot rolling step; heat-treating the stack, w

Assignees

• Thyssenkrupp Steel Europe Ag
• Thyssenkrupp Ind Solutions Gmbh

Inventors

• Linke Natasja
• Kern Andreas
• Tschersich Hans-Joachim
• Leuschen Guido

Classifications

• C21D6/004

  containing Cr and Ni · CPC title

• C22C38/04

  containing manganese · CPC title

• C22C38/54

  with boron · CPC title

• C21D6/008

  containing Si · CPC title

• B23K2103/04

  Steel {or steel} alloys · CPC title