Characteristics of Cold Rolliong in Consideration of Negative Forward Slip Ratio

(Received on February 8, 1994)

Toshiyuki SIIIRAISIII, Hiroyasu YAMAMOTO, jyun HASHIMOTO and Teruhide N11TOME

Forward slip ratios in tandem cold mills become negative after too much cold rolling with- out change of work rolls. Such cold rolling conditions can not stand up in the traditional theory using Coulomb's law of friction. From the experiments and analytical simulations of cold rolling with a 4-high mill, the relation between the relative speed ratio and the fric- tion coefficient is clarified.The friction coefficient increases as the relative speed ratio increases. The theory using such a relation stands up in the condition of negative forward slip ratios.The calculated values such as rolling load,rolling torque and forward slip ratios are consistent with experimental ones.

Keywords:sheet rolling, experimental analysis, cold rolling,forward slip ratio,load,torque,friction coefficient,relative speed ratio.



Characteristics of UR-E-UF Tandem Reverse Rolling for H-Beams

(Received on February 28, 1994)

Yoshiaki KUSABA, Haruo YAMAGTJCHI, Hiroshi SHIKANO and Hideo KIYOTOU

The authors have developed a new rolling method for H-beams, in this method, three stands, which consist of a universal roughing (UR) stand, an edging (E) stand, and a uni- versal finishing (UF) stand are arranged in tandem and H-beams are reverse-rolled through these stands. To produce H-beams by this layout, width-adjustable horizontal roll is ap- plied to the UF stand. In this paper, rolling characteristics of the present methods are examined by UR-E-UF model rolling experiments and FEM analyes of beamblank-deformation at breakdown passes. As the result, the rolling rate is increased by 35 %, compared with the conventional mill-layout of UR-E and UF.

Keywords:H-beam, universal rolling, tandem mill, adjustable roll, expermental analysis



Dynamic Simulation of Integrated Processes in the Cold Mill Complex

(Received on March 8, 1994)

Susumu YAMAGUCHI and Hiroji BABA

A dynamic simulation program which makes possible the exact prediction of production capabili- ties of integrated production lines In a cold mill complex, such as, continuous annealing lines and continuous descaling and cold rolling mills, is developed. The program is able to simulate the strip behavior in the integrated processing lines and helps to determine the optimum speci- fications of the complicated production lines.

Keywords:simulation, lntegratetl processing line, process design.i-olling



Roll Surface Temperature and Heat Flow in Cold Rolling

(Received on April 1, 1994)

Takeshi YONEYAMA, Takeshi HORI, Hiroshi KIMURA, Ikuya HOSHINO and Misao KOKUBO

Temperature and heat flux on the roll surface have been measured in aluminum cold rolling. The influence of several factors on the temperature increase and heat flow at the arc of contact between roll and strip has been investigated. Heat flow from the strip to the roll surface in the arc of contact gradually decreases with the gradual increase of the roll surface temperature in the rolling process of a coil. Heat flow and its rate in the total heat generation increases as the high flow stress of the strip increases the rolling force. Coating on the roll surface reduces the heat flow to the roll. The numerical result of the increase of roll surface temperature and heat flow using the rolling force and rolling power approximately agrees with the measured data.

Keywords:rolling, temperature, measurement, heat flow, aluminum



Forming of a Spur Gear by Use of a Liquid Lubricant
- Precision Cold Die Forging of Actual Gear Toothed Products Utilizing Divided Flows I

(Received on May 25, 1994)

Kyoichi OHGA, Hiroyuki ANDO and Kazuyoshi KONDO

A new precision cold die forging process, a combination of the conventional closed die forging with the process utilizing divided material flows, is applied to an actual steel spur machine gear. A low carbon steel, a chromium alloyed steel and a Ni Cr No steel of SNCK are examined as the test material. A commercially available liquid lubricant is newly adopted. Steel gear parts are forged successfully even with the liquid lubricant as well as with the traditional complicat- ed soap and phosphate lubricant. Therefore, the treatment will be much more simplified. The fill- ing up process into a toothed die cavity is not so much influenced by the variation of the test material. It is concluded that a good shaped product can be obtained under the working pressure as high as three times of the flow resistance. When SNCH is used, a spur gear product with the tooth width of five times the module, can be rorged precisely under the compressive stress of 2700HPa without any intermediate annealing and any re-lublication treatment.

Keywords:cold die forging, forming limit, divided material flows, Lwo steps method, steel@material, spur gear, liquid lubricant, low working pressure.



Effect of Draw-in Control of Flange by Localized Drawbead in Press Forming of Model Engine Oil-pan
A Study of Drawbead Clamping of Flange in Press Forming of Sheet Metal V

(Received oii June 1, 1994)

Masayasu KoilMA

Effect of the restraint of flange draw-in by localized drawbead on failures in deep drawing of such a part with a large difference in depth as an engine oil-pan is investigated experimentally by using a laboratory die of model oil-pan. During early stage of drawing, the excess of flange draw-in into the shallow die cavity caused by preceding flange draw-in into the deep die cavity grows wrinkles in transition region where the depth ch4nges. The drawbead arranged along the edge of die cavity near the transition region is effective to reduce the excess of flange draw-in toward the ,A,rinkling region. The amount of wrinkle, evaluated by the excess of profile length of the line crossing the wrinkling region, delreases with the increase in the area of longitudinal section of bead. The drawbead has also a function of controlling the thickness reduction at the potential fracture portion on the wall of the transition region.

Keywords:sheet metal forming, deep drawing, oil-pan, localized drawbead, transition wrinkles, flange wrinkles.



Evaluation of the Cooling Effect Based on the Measurement of Roll Surface Temperature and Heat Flux

(Received on April 1, 1994)

Takeshi YONEYAMA, Takeshi HORI, Hiroshi KimURA, Ikuya HOSHINO and Misao KOKUBO

Roll surface temperature and heat flux at the contact with coolant have been directly measured by the temperature sensor embedded on the roll surface. Heat flux is large at the region where the coolant dashes against the roll surface but relatively low at the other region where the coolant flows on the surface. Heat flux from the roll to coolant is accelerated by the temperature difference between the coolant and the roll surface and by the flow rate of the coolant. Differences by the spray types of flat and oval nozzles and efficiency of the twist angle of the spray have been investigated froni the temperature data. Heat transfer coefficient in each spray has been estimated froni the comparison between the measure data and the numerical analysis. Local heat transfer effect will be evaluated by these direct measurements of temperature and heat flux on the roll surface in actual rolling.

Keywords:rolling, measurement, temperature, heat transfer, cooling, sensor



Effect of Expanding Type Pre-Forming on Cross-Sectional Shapes of Square Steel Pipes Formed by Extroll-Forming

(Received on April 13, 1994)

Yoshitomi ONODA, Takuo NAGAMACHI, Sadao KIMURA and Takeo KITAWAKI

In order to manufacture square steel pipes (I 50, 152, 154mm in height, SUS304) which have small outer radius and small thickness change of each comer zone by an extroll-forming mill, an expanding type pre-forming process is introduced for imposing the peripheral bending under tension on the designated portions of round pipes (190.7mm in outer diameter, 3.9mm in wall thickness) that correspond to the comer zones of finished products. The main tools of the pre-former are the retainer with four punches arranged at equal angle (90') and the axially movable tapered mandrel. Cross-sectional shapes (thickness strain, outer and inner curvatures of comer zones, flatness of sides) of the formed square steel pipes are investigated and compared with the results obtained by the conventional extroll-forming. The results show that the cross-sectional shapes of the fon-ned pipes can be remarkably improved by introducing the pre-forming process.

Keywords:roll forming, tube fon-ning, extroll-forming, pre-forming, round welded steel pipe, square pipe, non-driven grooved rolls.



Rolling of T-Shaped Profiled Metal Strip by Calibered Satellite Roll Method
-Studies on Satellite-Mill Rolling VI

(Received on May 11, 1994)

fliroshi UTSUNOMIYA and Yoshihiro SAITO

The satellite mill is used for rolling of T-shaped profiled aluminum strips from flat strips. The mill consists of one central roll and five satellite rolls arranged along the periphery of the central roll. Passing through five gaps between a central roll and satellite rolls, flat strips are continuously rolled into profiled strips. All these rolls are driven at an equal peripheral speed in order to restrain elongation and to promote transverse metal flow. Some rolling experiments have been performed on the mill with a flat central roll and calibered satellite rolls (calibered satellite roll method). The deformation and force characteristics are investigated. Experimental results are compared with those obtained by conventional caliber rolling and with those obtained by calibered central roll method. The main results are as follows. (1) In the satellite-mill rolling, the elongation is restrained, the lateral spread is enhanced and the profile of cross section is much improved. (2) The transverse metal flow in the calibered satellite roll method is larger than that in the calibered central roll method.

Keywords: section rolling, profiled strip, deformation-load property, satellite mill, calibered satellite roll method.



Numerical Analysis for predicting Dimensional Accuracy under Thermal Influence during Repeated Forward-Backward Cold Extrusion

(Received on June 10, 1994)

Tooru KAWABE, Takeshi KATO, Hideo TOKUMITsu and Tomovuki WADA

An improved analytical method is proposed with the aim to predict the dimensional accuracy of cold forged products in repeating operation. The method gives optimum operation and better understandings of the process, and minimizes harmful influences of the heat accumulated in die assemblies on the dimension of products. The principal procedure is composed by combining the coupled analyzer of deformation and heat conduction for single operation with the thermal analyzer for repeating operation. The main aim of the method is the full computational simulation of dimensional change of products in forward-backward cold extrusion processes from the beginning to quasi-steady states under thermal cyclic influences. Some characteristics obtained by the numerical simulations concerning temperature rise and thermal stress of workpieces/products and die assemblies indicate the effective perfon-nance of the proposed method more satisfactory than that of the previous model.

Keywords:cold forging, numerical analysis, thermal influence, final shape, product accuracy.



Influence of Environmental Temperature on Elastic Modulus of Polymers

(Received on June 29, 1994)

Tetsuya AYA, Toshio NAKAYAMA and Yuzuru FujITA

A spherical model associated with the scaler potential theory was proposed by the authors to understand the effect of hydrostatic pressure on the elastic module of poIymers, previousIy. In the present paper, the modeI is extended to predict and anaIyze the infIuence of environmentaI temperature The extended theory agrees w i th the experimental data and explains the influense of environmentaI temperature. As the environmental temperature rises, the elastic modulus decreases in the authors' expriment as well as in other cases. According to this theory, the result is explained in terms of the change in the potential shape with temperature. The polymers tested are high-density polyethylene (HDPE), poly (vinylidene fluoride) (PVdF), polyoxymethylene (POM) , polyamideimide (PAI) and polyetheretherketone (PEEK).

Keywords:tension test, polymer, environmental temperature, hydrostatic pressure, elastic modulus,Young's modulus, intermolecular force, potential theory, elastic deformation,glass-transition temperature



Forming of Tooth Parts by Fully Enclosed Die Forging with Punch Indenter

(Received on June 30, 1994)

Keiou NISHIMURA, Tadasu MURAKAMI, Hiroo TAKAHASHI and Yoshiaki SEKIMOTO

Fully enclosed die forging with punch indenter has advantage of lower forming load than conventional closed die forging, because stressing area on the former is smaller than the latter. Deformation behavior in a forming of tooth parts from cylindrical billet by fully enclosed die forging with punch indenter is investigated. The material used is pure aluminum and pure lead. on this forming, deformation process is divided three steps, (I)first stage is before reaching the tip of material to end of die cavity,(II)second stage is filling the material to lower region of die cavity, (III)third stage is filling the material to upper region of die cavity. Normalized forging stress required almost full filling die cavity is 10 times by yield stress of formed materials.

Keywords:forging, experimentally analysis, fully enclosed die forging, tooth parts,metal flow, force



Microscopic Deformation and Fracture Behavior of Alumina Particle Reinforced Aluminum Matrix Composites

(Received on June 29, 1994)

Naoyuki KANETAKE, Masahiro NomURA and Takao CH0H

The in situ tensile test in a scanning electron microscope is done for A]203 particle reinforced 6061 aluminum composites to observe directly microscopic deforniation behavior durin(, tensile loadine. The composites are produced by powder extruding and melt stirring niethods. In the latter nictliod the composite is also extruded under the same condition as the former method. The chan!!c in microstructure of the composites is obscrvcd continuously during tensile loadina, and the fracture surface is analyzed. Some interface debondini! and particle fractures are initiated at the nican load between the yield and maximum tensile stresses in both composites. The microcracks do not propa(,ate because of ductility of the niiti-ix, but the nuiiibcr of new microcracks is increased with increasing strain, resulting, in occurrence of cracks at aliilost all particles at the maxiiiiuni loadinc, point. Both cracks due to interface debondin2 and particle fracture can be found in the powder extruded composite, and fine dimples of the matrix aluminum and a part of the ori-inal surface of the particle are observed on the debonded particle. Almost all cracks are due to the interface debondin- iii the nielt stiri-cd coniposite, and the very brittic fracture surface is obscrved on the debonded particle.

Keywords:nietal niatrix coniposite, tensile deformation, fracturc, microstructure.



Effect of Tensile Deformation on Mechanical Properties of Particle Reinforced Aluminum Composites

(Received on August 3, 1994)

Naoyuki KANETAKE, Hajime SAIKI and Takao CHOH

The chan2cs in niechanical properties and iiiicrostructurcs brought about by tensile deformation at room temperature are investigrated for Al203 and SiC particles reinforced 6061 alminum matrix composites. The composites are prepared by the powder extruding method. The tensile properties and microstructures are investigated for the composite speciniens which are subjected to various tensile pre-straining and subsequent heat treatment. The proof stress and tensile strencth are decreased with increasin- tensile pre-strain, and it is not dependent on the particle niaterial, size and the subsequent heat treatment. The uniform elongation is not affected by the pre-straining, while the total elongation namely the localized elongation is decreased with increasing tensile prestrain. The decreases in proof stress, tensile stren(,th and total elongation can be directly related with the de(yra- dation in the niicrostructure such as debondin- of interfaces and the particle fracture brought about by the tensile@pre-straining.

Keywords:Coniposite niaterial, Powder extrusion, Tensile deformation, Material property, Microstructure.



Numerical Analysis of a Circular Plate Clamped at the Periphery under the Shock Loading by Employing the Effects of Strain and Strain-Rate Hardening, and Thickness

(Received on August 15, 1994)

Masahiro FUJITA, Yasuo ISHIGORI, Minoru MOCHIHARA Hiroo OSAKA and Shigeru ITOH

The deformation process of a circular plate clamped at the periphery has been numerically analyzed by using the finite-difference method under the condition that the plate is uniformly pressurized by a shock loading. Two analytical results, such like the membrane and the plate shell, are discussed, and the difference of deformation mechanism is clearly indicated. It is worth while to note that the effect of the bending waves on the deformation mechanism is identified by the analysis. The effects of strain and strain-rate hardening on the deformation process are also confirmed.

Keywords:sheet metal forming, high-energy-rate forming, explosive forming, numerical@analysis, FDR, shock loading, free stretch forming, bending wave, deformation process