Innovative concept of coiling machine integrated with rolling mill to replace the stirrup making practices

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 04 Issue: 10 | Oct-2015, Available @ http://www.ijret.org 448
INNOVATIVE CONCEPT OF COILING MACHINE INTEGRATED
WITH ROLLING MILL TO REPLACE THE STIRRUP MAKING
PRACTICES
T.A. Madankar 1
, M.M.Gupta 2
, J.P. Modak 3
1
Research Scholar & Assistant Professor, Department of Industrial Engg, Shri. Ramdeobaba College of Engineering
& Management, Nagpur, India. Madankarta@Rknec.Edu
2
Professor, Department of Mechanical Engg., Shri. Ramdeobaba College of Engineering & Management, Nagpur,
India.Guptamm@Rknec.Edu
3
Emeritus Professor & Dean (R&D), Department of Mechanical Engg., Priyadarshani College of Engg, Nagpur,
India. Jpmodak@Gmail.Com
Abstract:
Building Construction Involves Use Of Stirrups To Give Strength To Columns And Beams And Are Widely Used In Various
Shapes In Steel Reinforcement. It Is Regular Practice To Make Stirrups On Construction Sites. Existing Engineering Standards
Recommend Use Of Continuous Helical Coil For Better Strength Of Structure But It Is Having A Very Rudimentary Level Of
Technology. Hence This Work Focuses On Developing A Coiling Machine As An Integrated System Of The Rolling Mill Where
The Steel Bars Are Produced. The Integrated Coiling Machine Will Overcome Almost All Problems And Limitations Associated
With Manual Stirrup Making And Even Of Semiautomatic And Full Automatic Stirrup Making Machines. This Paper Embarks On
Integration Of Stirrup Making Activity With Rolling Mill So As To Take The Advantages Of Plastic Deformation Of Steel At
Elevated Temperature, Imbibing The Metallurgical And Mechanical Properties And Eliminating Residual Stresses Compared To
Todays Stirrup Making Practices.
Key Words: - Stirrup, Rolling Mill, Helical Coil, Coil
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1. INTRODUCTION
Civil structure without reinforcement is beyond imagination.
Concrete material is several times strong in compression but
weak in tension. If a concrete block is subjected to shear
stress, failure may occur by diagonal tension. To safeguard
the concrete structure against such failure, reinforcement is
required. This reinforcement is called shear reinforcement
which is provided by the element called as stirrup or lateral-
tie. Stirrup is one of the indispensable elements of
reinforced cement concrete used for avoiding sagging of
horizontal beam and buckling of vertical column along with
the longitudinal member of it.
According to need of shapes of column and beams various
shapes of stirrups are used such as rectangular, square,
circular, triangular, hexagonal, etc. made out of, 8mm,
10mm, 12mm either in plain mild steel or torr steel. Steel
used for reinforcement is Fe 250, Fe 415, Fe 500 or
equivalent grade of steel. Existing engineering standards
recommend use of continuous coil for better strength [1]. It
out-ways reduction in strength because of discrete stirrups.
The reinforcement structures using various shapes of
stirrups are as shown in following figures.
Fig.1.1RectangularStirrups Fig.1.2 Circular Stirrups
Fig.1.3LongStructurewith
Fig.1.4 Helical Coil Stirrup Circular Stirrups

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Fig.1.5 Structure with Continuous Helical Coil
Making a continuous coil on construction site experiences
large difficulty. In the same way making it in factory
involved loading and unloading of bars and additional
transportation. Special feeding mechanism is needed to feed
the bar in stirrup making mechanism which is also used for
coiling the bar. Especially it is cold working process.
Therefore it consumes more power[2].
Instead of taking the bar on construction site or in the stirrup
making factory, the continuous coiling can be done at the
outlet of last stand of rolling mill. The attempt is made to
utilize the momentum gain by the bar due to rolling action
of the rollers for feeding it in coiling mechanism. The entire
process is carried out at elevated temperature. Thus heat
reduces the yield point due to softening of metal thereby is
an assurance of reduction in power requirement. This work
will examine the possibility of integration
2. PRESENT SCENARIO:-
Now days many types of mechanical equipments are used in
the construction processes. This mechanization allows an
extensive gain in saving of time, high productivity,
uniformity of product, eliminate or minimize human
intensive process, reduce health hazards, minimize the
wastage and reduce overall cost of product. However,
considerable amount of work on the construction side is
being done either by manual labor or semi- automated
machine. Similarly stirrups are made manually. Semi
automated or fully automated processes are also used for
manufacturing the stirrups. These processes are carried out
either on construction site or in the factory.
Various methods are used for making stirrups. The manual
process of making stirrups is extensively used in civil
construction. In this process of stirrup making, the specified
length of M.S. round bar is cut as per required size of
stirrup. The operator uses a wooden block as a platform for
bending on which three nails are fixed, around which the
bending takes place. The cut bar is passed horizontally
between the nails up to the chalk mark and bent using a
lever, about the nail through an required angle. After
completing one bend the operator lifts and reposition the bar
for the next bending. In this way the operator makes all the
required bends for making one stirrup. Number of specified
length of bars are cut from standard length of bar and last
piece of it may be wastage of process. Rectangular stirrup
making process is shown in Fig. 1.6.
Fig. 1.6 Rectangular Stirrup Making Process
(Conventional Process)
Semiautomatic machines for manufacturing of stirrups are
readily available in the market. The few machine
manufacturers are Consolidated Machine–Mumbai, RJS
Steel Fabricators LLC–Atlanta–Georgia, etc. Semiautomatic
processes are also designed & developed by researchers.
Vanalkar A.V.et.al., [2,3,4,5,6] designed & developed
semiautomatic motorized stirrup making machine. The
required length of bar is cut and placed in feeding
mechanism which further feed the bar to bending machine.
With the help of cam and follower mechanism the number
of require bends are given with specified angle to the bar for
making the stirrup. Such a machine not only increases the
production rate but also avoids the fatigue and muscular
disorder of the operator.
Fully automated machines controlled by computer are the
latest generation machine for making the stirrups and
commonly available in the market. Orient Agency-
Mumbai(India), Alibaba group-China, Xuchang Fengyida
Machinary Manufacturing Co. Ltd., China, etc are the
leading manufacturer in this area[1]. The roll of bar is
received from rolling mill. The complete roll is kept on
stand to feed the bar in machine with the help of feeding
mechanism. Massive power is required to feed the bar in
stirrup making mechanism. Bending mechanism provides
bends according to specified program prepared on computer.

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Any kind of shape of stirrup can be manufactured. The coil
stirrup may also be produced. Basically it is cold working
process. These machines are versatile in nature as various
shapes of stirrups can be made. Macello Del. F. patented
concept of automated stirrup making machine in 1979[7].
The rate of production in manual stirrup making process is
50 to 60 stirrups per hour & 100 to 150 numbers per hour in
semiautomatic machine depending on size of stirrups
[2,3,4]. The production rate also goes up to the 400
numbers per hour, whereas fully automated machine
produces more than 700 stirrups per hour [8].
3. LIMITATIONS IN PRESENT METHODS OF
STIRRUP MAKING:-
Facility of manufacturing the coil stirrup is not available in
manual or semi-automated processes. Ordinarily stirrup
making is the cold working process. It is observed that hair
cracks are developed on outer face of the bar during bending
in cold working process which drastically reduces strength
of stirrup. Reduction in size of bar and induction of residual
stresses in the bar during bending further reduces the
strength of material. Muscular disorder in operator,
inaccuracy in work, limited production rate, non- uniformity
in product, more time consumption, etc are the drawbacks in
manual stirrup making process. Transportation of long bar,
loading and unloading, shifting of bars at the stirrup making
factory, again shifting of stirrups to the construction site, etc
are the activities associated with present method of stirrup
making.
4.PROPOSED METHOD OF MANUFACTURING
HELICAL COIL STIRRUPS:-
In this paper, it is proposed that the bar coming out from the
last stand of rolling mill can be turned into coil by
integrating the coiling mechanism with rolling mill. The
emphasize is given for making the circular continuous coil
due to its simplicity in bending in the form of smooth
curvature. The outer fiber of bar is in tension whereas inner
fiber experiences the compression. To retain the given
curvature to the bar, it is essential to take the fibers at plastic
region of stress-strain curve. Elevated temperature of bar
lowers the yield point and hardness of the metal. The
analysis during bending is done for determining the strain
energy induced in the various sizes of the bar. Thereby net
power required for coiling is estimated. The amount of the
forces required for taking the sufficient fibers to the plastic
region is taken into account. The work encompass the
synchronization of hot rolled bar to be received at coiling
station. Due care should be taken while handling the bar
because of high temperature and high speed of bar.
Typically with hot condition, handling of the metal is
hazardous. It is observed that the linear speed of the bar is
between 3.5 to 4.0 m/s along with the temperature around
6000
C, at the last stand of rolling mill. Considering all above
mentioned issues the two basic types of mechanisms are
proposed. One is drum coiling mechanism and another one
is dowel mechanism as shown in the figure 4.1 and 4.2
respectively.
Fig 4.1 Drum Coiling Mechanism
Fig 4.2 Dowel Mechanism
In drum coiling mechanism, a stationary saddle is used to
turn the bar over the surface of rotary cylindrical drum. The
arrangement is made to feed the bar in the gap between
saddle and drum. The drum is mounted on the shaft from
one end where as the end is kept open to remove the coil
from mechanism. The spinning speed of drum is needed to
synchronize with the linear speed of bar coming out from
rolling mill. In dowel mechanism, the dowels are used to
coil the bar by shifting the position of dowels with reference
to rigid guide. The dowels are mounted on positioning plate.
The bar coming out from rolling mill is fed to the stationary
guide. Maintaining the straightness and providing the rigid
support to the bar while bending by the dowels is the
functional requirement of the guide. As soon as the bar
reaches in the gap between the dowels, positioning plate
provides the required position to the dowels for turning the
straight bar into coil as shown in fig 4.2. Coil collector is
kept below the coil for collecting it. Both the mechanisms
have their merits and demerits. Drum coil mechanism has its
own limitation of producing the different diameter of coils
as per the need of civil construction. The series of limited
varying diameters of drums is to be kept for the production
of different diameters of coils. Changing the drum for every
required change in diameter consumes the manpower and
time. Maintenance and balancing is another issue with the
drum mechanism. Dowel mechanism overcomes the
limitations of first mechanism. The change in diameter of
coil is obtained by only changing the relative position of
dowels. Therefore set up time to change from one diameter
to another is absolutely zero. All limitations of drum coil
mechanisms are overcome by dowel mechanism. The
mechanism to be deployed should support high mechanical
working with securities and safety.

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This method produces coils in rolling mill, itself avoiding
transport for stirrup making and according to need it can be
cut to use as a individual stirrup or continuous helical coil.
The entire coil making process is carried out at elevated
temperature thereby helping in maintaining the metallurgical
and mechanical properties of material[9]. In addition to this
there is no wastage of bar due to continuous coiling process.
5. ADVANTAGES OF PROPOSED METHOD
The proposed method of manufacturing the coiling stirrup
gives the following advantages:-
[1]. Hot condition of bar gives the advantages of bending
at low power in plastic region.
[2]. No necessity of feeding mechanism.
[3]. The large amount of power can be saved for making
the stirrups.
[4]. It avoids the hair cracks.
[5]. The coil passes through oblivious annealing, thereby
relieving the residual stresses. Therefore coil stirrup
has more strength than the stirrup produces in cold
working process.
[6]. Due consideration can be given in sizing of the bar at
the last stand of rolling mill for taking the care of
reduction in size of bar in bending.
[7]. Different diameter of coil can be manufactured only
by changing the position of bending pins.
[8]. Entire helical coil can be used as continuous stirrup.
[9]. As per the need, helical coil can be cut to make
conventional stirrups.
[10]. Coil so produced has reasonably small length
compare to original length of bar. Material handling
becomes convenient and easier. Commercial bars are
around 6 meters in length. The handling of long bars
are cumbersome.
[11]. Use of such coils reduces onsite working. It saves
labor and space.
[12]. Overall cost of stirrup could be reduced.
6. LIMITATIONS OF PROPOSED METHOD:-
Safety and synchronization with the rolling mill of speed of
bar at elevated temperature is a major limitation that needs
attention while designing coil making machine.
7. CONCLUSION
The integration of coiling mechanism with a rolling mill is a
novel approach and would be a revolution in the field of
stirrup making industry. It would provide a competitive edge
in construction industry by eliminating wastage of time,
material, money and energy involved ordinary stirrup
making practices. The quality stirrups would lead to
enhanced life of building structures as it would be produced
in hot condition i.e. in plastic form of material, where
mechanical and metallurgical properties are maintained to
best values and overcoming the problem of residual stresses
and surface cracks in ordinary stirrup making practices.
Hence it can be concluded that there is a need to develop
proposed coiling machine integrated with rolling mill.
REFERENCES
[1]. Indian Standard Code of Practice for Plain and
Reinforced Concrete (4th
Revision) - IS Code 456-
2000, BIS, New Delhi,(2000).
[2]. Padole P.M.& Vanalkar A.V., “Feeding System using
Gearised DC Motor For Stirrup Making Machine”,
Proceeding 10th
National Conference on Machines and
Mechanisms, Dec. 2001, IIT Kharagpur, India, pp.
255-260
[3]. Vanalkar A.V.& Padole P.M.,“ Design, Development
and Fabrication of Stirrup Making Machine‟,
Proceedings of 9th
national Conference on Machines
and mechanisms, December 1999, NACOMM 99, IIT,
Pawai, Mumbai, India, pp. 341-352
[4]. Vanalkar A.V.& Padole P.M.,“ Mechanism Synthesis
for Stirrup Making Mechine. Proceeding, 4th
International Conference on Mechanical Engineering,
ICME 2001, BUET, Dhaka, Bangladesh, pp271
[5]. Padole P.M.& Vanalkar A.V.,“ Optimum Design of
Mechanism for Stirrup Making Machine – A
Computer Approach”, 11th
National Conference on
Machines and Mechanisms, IIT, Chennai
[6]. A.V, Vanalkar et. al.,“ Development of stirrup making
machine”, International Journal of mechanism and
Machine Theory, (SLSMMT)2001,pp 37-39
[7]. United State Patent patented by Del. F. Marcello
(1979) [4]. file:///H:/Stirrup Making machine.
[8]. Ikhar S., Vanalkar A. and Modak J.P., “Formulation of
Field Data Based Model to Co-relate the Performance
of Stirrup Rod Cutting Operation with Independent
Variables of Activity”, Industrial Engineering Journal,
Vol. VI & Issue No. 3,pp40-44, March 2013
[9]. Outinen J. & Makelainen P, „ Mechanical Properties
of Structural Steel at Elevated Temperatures and After
Cooling down‟. Second International Workshop –
Structure in Fire, Christchurch, March 2002.

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