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European Journal of Applied Sciences – Vol. 11, No. 6
Publication Date: December 25, 2023
DOI:10.14738/aivp.116.15795
Yang, C.-C., Nguyen, H. Q., & Wang, K.-H. (2023). The Forming Analysis of SCM440 Alloy Steel Hexagon Head Flange Bolts.
European Journal of Applied Sciences, Vol - 11(6). 01-13.
Services for Science and Education – United Kingdom
The Forming Analysis of SCM440 Alloy Steel Hexagon Head Flange
Bolts
Chih-Cheng Yang
Department of Mechanical and Automation Engineering, Kao
Yuan University, Taiwan
Hong Quy Nguyen
Graduate School of Metal Technology Industry, Kao Yuan
University, Taiwan
Kuo-Hsiang Wang
Graduate School of Mechatronic Science and Technology, Kao
Yuan University, Taiwan
ABSTRACT
In this study, a multi-stage cold forming process for the manufacture of hexagon
head flange bolts is studied numerically with SCM440 alloy steel. The cold forming
process through five stages includes forward extrusion, two upsetting operations,
hexagonal trimming and circular trimming. The numerical study of cold forming is
conducted using the code of DEFORM-3D. The formability of the workpiece is
studied, such as the effect on forming force responses, maximum forming forces,
effective stress and strain distributions and metal flow pattern. In the five-stage
forming process, in the two upsetting and one hexagonal trimming forming stages,
the effective stresses in the head of the workpiece are significantly high, and the
effective strains are also significantly high due to large deformation. The flow line
distributions are also very complex in which the flow lines in the trimming region
of the upset head are severely bent, highly compacted, and eventually fractured
due to excessive trimming. For the maximum axial forming force, the fourth stage,
which the head of the workpiece is heavily trimmed into a thick hexagonal shape,
is 1,360.4kN which is the largest among the five stages due to the large amount of
trimming. However, for the forming energy, the second stage, which the workpiece
is upset into a conical shape, is 9,841.0J which is the largest among the five stages
due to longer acted axial forming stroke. The total maximum axial forming forces
from the first to the last stages are 3,608.8kN and the total forming energies are
about 26.16kJ.
Keywords: cold forming, hexagon head flange bolt, formability, forming force.
INTRODUCTION
In the field of modern industry, bolts play an important role as an indispensable connecting
component in the manufacturing and maintenance of mechanical equipment. The SCM 440
alloy steel hexagon head flange bolts are high-strength bolts widely used in critical
applications. The cold forming process involves mechanical issues and is affected by material
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European Journal of Applied Sciences (EJAS) Vol. 11, Issue 6, December-2023
properties. Cold forming is performed at room temperature and is commonly used in many
industries, especially in the manufacture of fasteners and specialty parts.
In the cold forming process, punches and dies are subjected to high stresses. Predicting
forming forces and stresses is important for design of punch and die and the selection of
forming machine. Many cold forming applications use numerical simulation to predict and
analyze forming designs. Altan and Knoerr [1] applied the 2D finite element method to
investigate suck-in type extrusion defects, bevel gear forging, stress analysis of forging tools
and multi-stage cold forging designs. Lee et al. [2] designed a process sequence for multi-stage
cold forging with the rigid-plastic finite element method to form a constant-velocity joint
housing with shaft. They investigated velocity distributions, effective strain distributions, and
forging loads, which are useful information in process design. Joun et al. [3] proposed a
numerical simulation technique for the forging process with a spring-attached die. A penalty
rigid-viscoplastic finite element method was applied together with an iterative force- balancing method. They investigated significance of metal flow lines for quality control and
the effects of spring-attached dies on the metal flow lines and the decrease in forming load.
Roque and Button [4] applied the application of a commercial general finite element software
of ANSYS to model a forming operation. They developed models to simulate the ring
compression test and to simulate an upsetting operation which was one stage of the
automotive starter parts manufacturing process. McCormack and Monaghan [5] numerically
analyzed the cold-forging process of a hexagonal head bolt using the finite-element analysis
(FEA) code of DEFORM. The FEA analysis indicated that the highest stress concentration
occurred within the body of the tool and not along the contact surfaces.
A three-stage cold forging process to form the spline shape in the head of an aerospace
fastener was proposed by MacCormack and Monaghan [6]. They gained insight into the
operation by numerically analyzing the strain, damage, and flow patterns for all three stages.
In order to analyze the formability of the multi-stage forging process, Park et al. [7] applied
the finite element method to establish a systematic process analysis method for the multi- stage forming of a constant velocity joint outer race. Farhoumand and Ebrahimi [8] applied
the FE code ABAQUS to the analysis of the forward-backward-radial extrusion process to
investigate the influence of geometric parameters such as die corner radius and gap height
and process conditions such as friction on the process. The numerical results are compared
with experimental data in terms of forming loads and material flow in different regions. The
hardness distribution of the longitudinal section of the product was used to verify the strain
distribution obtained from the numerical analysis. Paćko et al. [9] presented an application of
the finite element analysis for prediction and optimization of a bolt forming process. The
investigated bolt forming process consisted of six stages including cutting, three upsetting
stages, backward extrusion, and trimming. Several tool modifications were proposed and
analyzed employing numerical simulation. Jafarzadeh et al. [10] applied the FE code of
DEFORM-3D to study the transverse extrusion process to analyze the effects of some
important geometric parameters such as initial billet dimensions, gap height and friction
conditions on the required forging load, material flow pattern and effective plastic strain
distribution. They showed that the gap height had the greatest influence on the forming load
and material flow. This study analyzed and compared 4 and 5 stages of fasteners. They used
the FE code of DEFORM-3D to inspect the effective stresses, strains and velocities of objects