Effect of Tension Leveller at Entrance Section of Pickling Line

(Received oil October 7, 1993)

Yoshiyuki KASEDA, Takeshi MASUI, Tsuyoshi NUNOKAWA and Mamoru NISHINO

Tension levellers which are effective to correct flatness defects of thin strips, are widely used for recoiling and shear lines. 'De utilization of a tension leveller is gradually expanded to continuous annealing lines, continuous galvanizing lines, and such like. In this report, the ability of descaling was compared between a rolling mill and a tension leveller at the entrance section of a pickling line. From the model tests, it was confirmed that it is possible to flatten hot rolled strips directly without causing sur-face defects. The hot rolled strips become flat as cold ones. It was made clear that levelling has same effect on descaling as rolling. It is also effective to prevent strip wander- ing in the line because strip camber is corrected simultaneously. Utilizing a tension leveller for the existing pickl- ing line, hot rolled strips which were flat as cold rolled strips, were produced. Productivity was also increased by the stable operation of the line.

Keywords:shape correction, tension leveller, model simulation, descaling, pickling line, strip camber, hot rolled@strip



Springback Analysis of Stretch-Bent Sheet Metal and Experimental Verification
Springback Analysis of Sheet Metal I

(Received on November 16, 1993)

Toshihiko KUWABARA, Susumu TAKAHASHI, Kohji AKIYAMA, Kenji ITO and Yohsuke MIYASHITA

A program code for predicting springback of a metal strip subjected to stretch-bending is developed . The calcula- tion method of this code is based on the modified total strain theory proposed by Baba and Tozawa and is applica- ble to the normal anisotropic material with the n-th power hardening law. Two types of stretch-bending experiment, bending after stretching (TM) and re-stretching after TM-process (TMT), are per-formed using Al-killed steel sheet (SPCE) and sheet aluminum alloy (A5182-0), and the amount of springback is compared with the calculated re- sults. The results obtained are as follows: 1) the experimental results are in good agreement with analytical results for a wide range of bending radii and loading conditions; 2) the n- and F-values to be used in the springback analy- sis should be determined from the same strain range on an uniaxial stress-strain curve as that caused in the actual bent strip; 3) TMT-process is effective in reducing springback; 4) the amount of springback decreases with increas- ing the n-value and the Young's modulus or with decreasing the revalue and the F-value of the specimen. 5) This program code is also effective in predicting the springback of products having plural bending radii.

Keywords:stretch-bending, springback, numerical / experimental analysis, material property



Analysis of Cross and Longitudinal Buckle in Sheet Metal Rolling

(Received on February 14, 1994)

Kazutake KOMORI

In sheet metal rolling, shape defects called 'cross buckle' or 'longitudinal buckle' sometimes appear. They are many wrinkles like washboards, direction of the crest line of the former inclines at a certain degree to the rolling direction, while that of the latter is parallel to the rolling direction. In this paiper, analysis of the cross and the longitudinal buckle is performed by the theory of buckling. First, we obtain stress distribution of three dimensional sheet metal rolling near the exit cross section in the roll gap. Next, we calculate residual stress distribution near the exit cross section out of the roll gap. Further, analysis of buckling of a sheet is performed under the residual stress distribution, types of buckle, distance between neighboring two wrinkles and inclination of the crest line of the wrinkles to the width direction are obtained. We compare analytical results with published experimental ones, and find that the former agree well with the latter. ]fence, we prove that the method of analysis is appropriate, and that the cause of the cross and the longitudinal buckle is the residual stress distribution near the exit cross section out of the roll gap.

Keywords:strip rolling, numerical analysis, sliape defect, elastic buckling, residual stress, front tension.



Deformation Analysis of the Mechanical Variable Crown Roll
Development of the New Variable Crown (VC) Roll 2

(Received on March 4, 1994)

Atsushi TomIZAWA, Takeshi MASUI, and Eij'l IIIROOKA

It is indispensable to establish an optimum design method of a sleeve and bearings to achieve durability and reliability of the mechanical Variable Crown Roll(New VC Roll). In this paper, a defomiation model of the New VC Roll, which provides basic data for design, has been developed. Main results are as follows. (1) Rigidity of bearing was measured in model experimental apparatus and an equivalent Young's modulus of bearing was deriv- ed. (2) The deformations of a four high mill with the New VC back up roll subjected to load were analyzed by the finite element method (FEM). In this FEM model, a work roll, a sleeve, bearings and an arbor are divided in- to finite elements and contact on each part is taken into account. (3) The calculated bearing load and sleeve sur- face stress agreed sufficiently with those measured in the practical rolling mill. (4) It is a key technology to sup- press contact stress concentrations b@een sleeve and bearing outer race in the New VC Roll. A FEM model was proposed and influences of outer race shape on contact stress are shown.

Keywords:sheet rolling, numerical analysis, FEM, Production system, flatness control, Lrown control



Two-Billets Extrusion with Modified Shape for Bonding Interface
Production of Clad Metals by Multi-Billets Extrusion 2

(Received on March 28, 1994)

Manabu KIUCHI and Michihiko HOSHINO

The multi-billets extrusion process, in which plural billets are extnided simultaneously and bonded into a unified product by using a specialiv designed guide-block, is developed. The guide-block makes the geometrn, of bonding interface between workpieces desirable for attaining mechanical bonding as ivell as metallurgical bonding. Through the experiments, Tin-Lead bonded sheets and A1050-(AI+10vo]%SiC)powder bonded sheets are made bN, this M.M.B. (Metallurgical Mechanical Bonding) process. Thc metal flows in M.M.B. process are investigated by using Plasticinc bilicts and the computer aided simulation technique based on the upper bound theorem. 'Me calculated results shoiv rather good agreement with the experimental measurements. Through the study, it becomes clear that M.M.B. process is capable of nianufacturing clad and/or bonded sheets of different materials.

Keywords:extrusion, metallurgical-bonding, mechanical bonding, clad sheet, 3-D upper bound anal)-sis.



Characterization of Two-Billets Extrusion for Making Clad Sheets
-Production of Clad Metals by Multi-Billets Extrusion 1

(Received on February 14, 1994)

Michihiko HOSHINO and Manabu KIUCHI

The multi-billet extrusion process has been investigated, in which plural billets are extruded simultaneously and bonded@into a unified product by using plural containers, punches, specially designed die and die holder. Experimeiitil investigation and mathematical simulation based on the upper bound theorem have been performed with aims to characterize this process As an example, two-billets extrusion for manufjeturing clad sheets have been tested and analysed. The calculated results conceming geometries of formed dead zones, flow bchaviour and extrusion pressure show rather good agreement with the experimental measurements. And the calculated results suggest that geometries of bonding interfaces are unsteady in the case of complcx extrusion from Tin and Lead billets. The mean yicld stress ratio of workpieces has much effect on the state of bonding and flow behaviour. Through the study, it has become clear that the proposed mathematical simulation method enables us to know the necessary conditions for simultaneous extrusion and bonding.

Keywords: multi-billet extrusion, bonding, clad sheet, upper bound analysis, 3-D analysis.



Adaptive Remeshing Method for Deformation/Thermal Coupled Rigid-Plastic Finite Element Analysis

(Received on April 20, 1994)

Nobuki YUKAWA, Takashi ISHIKAWA a d Koichiro NANBA

The adaptive remeshing technique is applied to the rigid-plastic finite element analysis coupled with the thermal analysis for simulation of materials forming processes. The error measures of both defor- mation analysis and thermal analysis are calculated. The difference of the distributions of two error measures, the change of the maximum error measure during the analysis of forming processes, and the meshes which control the maximum error measures of deformation or temperature below the limit val- ues, are discussed. Also an attempt to control both deformation and temperature errors measures si- multaneously is done.

Keywords: Numerical analysis, Finite element method, Forging, Extrusion, Adaptive remeshing



Three-Dimensional Coupled Simulation Technique for Roll Shift Mill and/or Roll Cross Mill and Its Application to the Rolling with Pair-Cross Mill

(Received on April 28, 1994)

Jun YANAGIMOTO, Manabu KIUCHI and Yasuyuki NISHIYAMA

The three-dimensional coupled simulation technique for roll shift mills and roll cross mills Is developed. This newly developed simulation technique, which is named as CORMILL System, is applicable to the analysis of various three-dimensional deformation characteristics of strips at roll gaps including cross-sectional symmetric metal flow with respect to the center of strip in width and thickness directions. CORMILL System is applied to a series of simulations in the hot strip rolling with pair-cross mill and rolling pressure distribution and lateral thickness distribution of rolled strip are successfully simulated. Through the investigation, it has become clear that rolling pressure distribution and lateral thickness distribution of rolled strip in the rolling with pair-cross mill are quite similar with those in the rolling with conventional 4-Hi mill with work roll crown which is equivalent to cross angle.