Rolling Characteristics of 4-Roll Mandrel Mill

(Received on September 13, 1993)

Toshio IMAE and Ken-ichi YAMAMOTO

A new type 4-roll mandrel mill is developed. The rolling characteristics of the mill are experimentally investigated. A model mill with 5 stands tandem is used in the experiment of hot steel rolling. The effects of rolling speed on rolling force, rolling torque, and thrust force of the mandrel bar in the 4-roll mill are as same as those in the 2-roll mill. The elongation can be controlled in the same manner as the 2-roll mill. The advantages of the 4-roll mandrel mill over the conventional 2-roll mandrel mill are as follows: (1) The bulge width of a shell can be kept constant more easily. (2) The tail end flare decreases remarkably. The 4-roll groove stand was installed in the final #8 stand in a practical mandrel mill instead of the conventional 2-roll stand. A crop loss of 50% decreases in comparison with that of the conventional mill.

Keywords:rolling, tube rolling, mandrel mill, 4-roll mill, seamless tubes, roll groove design, pass schedule



Intelligent CAD System for Cold Forging Using Fuzzy Theory
-Sorting Structure of Case Bases and Reasoning Engines II -

(Received on October 12, 1993)

Tsutao KATAYAMA, Ken-ichi AKAMATSU, Ryuichi YOKOGAWA, Kouji OKAMOTO and Kei HARA

in this work, we attempt to develop an intelligent CAD system by which designers can determine desirable forming processes of cold forging even if they have little experience with respect to forging process design. In the previous paper, it was reported that the developed system is able to design forming processes for two axi symmetric piercing hollow products by the case base and the fuzzy pattern matching . This paper deals with establishment of the sorting structure of the case bases and the reasoning engines and the selecting method of a case base and reasoning engine suitable for a product. By using this method together with the previously proposed method, it is shown that development of a generalized system is possible.

Keywords:cold forging, intelligent CAD system, case base, reasoning engine, fuzzy pattern matching, sorting structure.



Three-Dimensional Simulation Technique Based on Rigid-Plastic FEM for Asymmetric Shape Rolling and Application to Angle RollingƒBR„-Development of Computational Simulation System for Shape Rolling Processes I

(Received on November 9, 1993)

Jun YANAGIMOTO, Manabu KIUCHI, Kazuyoshi SHIBATA and Yukio INOUE

The computer aided simulation system for rolling, named "CORMILL (Computational Rolling Mill) System," is extended by introducing a new contact analysis method. In this method, the interference between workpiece and rolls is adjusted by moving the nodal points on the upper and lower surfaces of workpiece in the direction normal to the roll surfaces. The extended CORMILL System, which is based on Lagrange multiplier rigid-plastic FEM, is capable of analyzing various three-dimensional steady-state deformations including both bending and elongation of workpieces at roll gaps in asymmetric shape rolling processes. It is applied to a series of simulations of breakdown and finishing passes for angle rolling. The three- dimensional geometry at roll gap, contact pressure distributions and rolling force are calculated. It can be concluded that the present analysis system is capable of providing useful information and data for the design of pass schedules in shape rolling.

Keywords:numerical analysis, rigid-plastic FEM, angle shape rolling



Fundamental Deformation Behavior of Plane Strain Indentation by Using Punches of Rectangular Section

(Received on October 27, 1993)

Tsutomu OKADA, Kazunori KATO and Tadao MUROTA

Plastic forming of deep holes by indentation includes various difficulties about accuracy of a formed product, collapse strength of a punch, etc. . In this paper, experimental and theoretical studies have been performed about deformation behavior in plane strain indentation of one and two punches, and the following results are obtained. (1) In one punch indentation, two deformation stages exist --- an initial unsteady deformation and the steady stage after that. And forming accuracy of the wall of a hole is rather low at the former stage. (2) The punch stroke at the transition state into steady deformation stage is decreased by applying no lubricant at container surface and the accuracy of a hole is improved. (3) Similar two deformation stages also exist in two punches indentation. The punch stroke at the transition state into steady deformation about the region between a punch and a container wall is rather large. (4) Brief deformation behavior about two punches indentation are made clear by using upper bound analysis in wide ranges of forming conditions.

Keywords:forging, two punches indentation, plane strain deformation, upper bound analysis, deformation behavior, forming accuracy, moire method.



Forming Precision in Plane Strain Indentation of Rectangular Section Twin Punches

(Received on November 22, 1993)

Tsutomu OKADA, Kazunori KATO and Tadao MUROTA

In twin punches indentation, the interference of deformation around each punch is caused and deformation property becomes complicated. In this paper, the forming precision of a plane strain indentation of twin punches is studied and the following results are obtained. (1) In a strain hardening material, precision of both side walls of a hole becomes much better than that in a non-hardening material, though height of walls becomes shorter a little. (2) Precision of the outer wall of a hole is improved by holding the material at out-side of the hole in no deformation state, which is achieved by applying lubricant to punches and no lubricant to a container. (3) Precision of the wall of a hole is also improved by providing small radius at edges of a punch. (4) Ratios of material flow rates at inner and outer sides of a punch are calculated at various frictional conditions by an upper bound approach and they are expressed as contours in wide range of forming conditions.

Keywords: forging, twin punches indentation, plane strain deformation, upper bound analysis, deformation property, forming precision, moire method.



On Flow Pattern around Flow Front and Occurrence of Flowless Layers in Ceramic Injection Molding

(Received on November 25, 1993)

Ren Haw CHEN, Kazunori KATO, and Koichi ISHIHARA

The flow pattern in the longitudinal section of the barflow of a ceramic slurry has been examined by using tracers of a row of small holes, which are drilled in a specimen before an injection and whose locations after the injection are measured with a microscope. The pressure distribution in a die cavity are measured with pin type sensors. It is found that the flow pattern is quite different from that of a polymer melt. (1) Material near the flow front moves without deformation. It may possibly cause a welding defect because of cooling of the front. (2) Flowless layers are occurred along die surfaces and material flows only in the central part of the die cavity. This flow property causes considerable increase of pressure loss along the material flow. (3) Flow properties are examined concerning material temperature, die temperature and injection rate. Results of numerical calculation are in good agreement with the experiment. The analysis in this paper is useful for an approximate estimation of flow properties.

Keywords:injection molding, ceramics, friction property, flowless layer, fountain flow



Spreading of Flat Strip by the Convex Satellite Roll Method
-Studies on Satellite-Mill Rolling V

(Received on November 26, 1993)

Hiroshi UTSUNOMIYA, YOShihiro SAITO and Kosei MORITA

A new method which can spread the width of narrow flat strip is developed. The method is named "convex satellite roll method". The mill consists of one large flat cen- tral roll and five small satellite rolls arranged along the periphery of the central roll. Strips are continuously rolled through the five gaps between central roll and satellite rolls. All rolls are driven at equal peripheral speeds in order to restrain the elongation of strips. In the convex satellite roll method, each satellite roll has a different projection. At the first stage, a thin part is formed at the center of the strip. The thin part is widened step by step, and a wide flat strip is obtained finally. The deformation and force characteristics are investigated and compared with those in conventional rolling and with those obtained by the concave satellite roll method, in which grooved satellite rolls are used. The lateral spread by the convex satellite roll method is smaller than that obtained by the concave satellite roll method. However, the deformation of the strip rolled by the concave satellite roll method is more homogeneous.

Keywords: strip rolling, lateral spread, satellite mill, convex satellite roll method.



Drawbead Forces in Drawing of Sheet Metal@through Double Beads
A Study of Drawbead Clamping of Flange in Press Forming of Sheet Metal IV

(Received on July 9, 1993)

Masayasu KojIMA

Characteristics of drawbead forces induced by double beads in press forming of sheet metal are investigated experimentally to compare with the case of single bead that has the same cross section as the double beads. It is found for the double beads that , in a blankholding process, vertical drawbead force of the inner bead is remarkably larger than that of the outer bead. 'Men , the sum of them is about three times as large as the vertical draw- bead force produced by the single bead alone. During drawing operation, drawbead lifting force of the inner bead is also larger than that of the outer bead because of the increase in tensile force to draw the flange in and through the outer bead. For identical blankholder loads , the sum of the drawbead lifting forces of the outer and inner beads equals twice that of the single one. Both drawbead lifting forces induced by the outer and inner beads equally increase when the blankholder load increases. Draw stress necessary to let the flange pass through the double beads becomes about 1.4 times that of the single one.

Keywords:sheet metal forming, drawbead, double beads, single bead, drawbead lifting force, draw stress.



Deformations of Aluminum Alloy Tubes under Forming of T-Fitting

(Received on December 27, 1993)

Sadakatsu FUCHIZAWA, Kazuyuki KITAMURA, Michiharu NARAZAKI, Minobu SUKIMOTO and Isao WATANABE,

Forming of T-fitting from aluminum alloy straight tube is investigated experimentally. Used materials are A6063 seamless tubes made by drawing with mandrel, whose tempers are 0 (annealed), T7 (solution heat treated and then stabilized) and H18 (strain hardened). The diameter and wall thickness of tube are 40mm and 2mm, respectively. A 30mm diameter branch is formed laterally by application of hydrostatic internal pressure and additional axial compression. The influence of the material properties of the tubes, the value of internal pressure and the amount of axial compression on the height and shape of the formed branch, thickness distribution and metal flow is examined. To form a sound, unbuckled branch, it is essential to use soft tube material and to compress the tube maintaining the internal pressure sufficiently high below the bursting pressure.

Keywords: tube forming, experimental analysis, aluminum alloy tube, T-fitting.