The present invention relates to a process and apparatus or system
for making durable, heavy duty shank-hooks. More particularly this invention
pertains to a process for making heavy duty shank-hooks by employing the novel
apparatus or system developed as a special feature of the subject Application.
The system helps in developing a shank hook from a tested bloom of either
Class II or 20 MN2 or as per requirement of the customer which is transformed
into a forging bat capable of being bent and shaped into a shank hook as
mentioned above. Heavy duty shank hooks find extensive use in various fields
which are, inter alia, crane manufacture, ship building, overhead cranes, steel
plants, in ports/docks, in industrial establishments, in constructions/
erections, etc. In all such applications, the hooks used must be strong, durable
and capable of withstanding considerable stress and strain, apart from greater
lifting capacity without any sign of fatigue, deformity or structural weakness.
Overhead shank hooks available in the market till date are of light
capacity, usually not exceeding 100 tonnes in load test, as laid down in the
Indian Standards Specification IS-7847-1975 and IS-6294-1971. Such lifting tackles
are often insufficient or incapable of lifting heavier loads. With the advent of
heavy duty cranes and lifting equipments, the shank-hooks as available in the
market have been found to be inadequate.
Earlier, say 50 to 60 years back, overhead heavy duty lifting tackles like
shank hooks, shackles, links, yokes and the like were imported from abroad,
which were only forged, costly items and were in short supply. Non-technical
local fabricators of India took advantage of the situation and supplied hooks/
tackles made by slab cutting process with considerable margin of profit.
Heretofore hooks were made by one of the three procedures enumerated
below :

(i) by cutting the iron slab directly for imparting it the contour and
shape of a hook,
(ii) for heavy duty, hooks by adding a few pieces by welding and
imparting the shape of a hook or
(iii) by cutting an iron slab to assume a 'I' - shape and forging at the
shank portion only for satisfying a "microscopic test", but the
remaining portion of the hook formed by cutting in the form of
drawing and having the same remaining or retaining the structure
as in the original slab from which it is formed. Such a procedure
eliminates the cost of forging and bending process, and
simultaneously hoodwinking the inspection at the user's end, but
rendering the hook unsafe for working.
In the latter instance, microscopic grain structure will show the manner
in which the slab was rolled, but in the rounded portion the grain structure will
not follow the bend, rather the fabric or structure retains the flaws and becomes
susceptible to snapping or breaking unpredictably, particularly under enhanced
load conditions. The given structure of the hooks of present day procedure is not
at all compacted, like the forged material. Such abrupt and unpredictable
snapping of hook in its bent portion or lip is likely to result in serious
accidents, and hooks made this way easily developed fatigue leading to breakage
with disastrous consequences, causing injury or even loss of precious human
life.
The present invention aims at overcoming the shortcomings of the
conventional mode of making hooks, particularly shank hooks, by providing an
improved process and system for making such articles, which ensures safety in
handling enhanced load.

The principal object of this invention is to provide a process for making
durable hooks of varying capacities extensively used in various fields, e.g.
crane manufacture, ship building, overhead cranes, steel plants, in ports/docks,
in industrial establishments, in constructions/erections, etc., and a novel
system or apparatus for producing said heavy duty shank-hooks.
A further object of this invention is to provide a process for making heavy
duty shank hooks capable of lifting loads far in excess when compared to hooks
now in use.
A still further object of this invention is to provide a process for
preparing heavy duty hooks utilizing indigenous raw materials.
Another object of this invention is to provide an apparatus or system for
producing heavy duty shank-hooks capable of with standing considerable strain
and lifting heavy loads in excess of 200 mT, without showing any sign of material
fatigue with consequent breakage and adverse consequences.
Yet another object of this invention is to provide a system for producing
heavy duty shank-hooks made from indigenously available raw materials and by
using machineries designed and fabricated by the Applicants herein, which
obviate the need to use sophisticated imported machinery and/or attachments.
Still another object of this invention is to provide an apparatus or
system which is capable of imparting the desired shape to the shank hook using
a bat hammer-forged from a tested bloom by characteristic sequential operations.
The foregoing objects are achieved by the process of the present invention
for making durable, heavy duty shank-hooks of varying capacities, characterised
in that the said process comprises -

(a) selecting a bloom and subjecting it to close scrutiny to detect any
deformities, microcracks and/or blow holes;
(b) forging the bloom with a heavy duty steam hammer after bringing the
said bloom to a plastic state by heating and forming a bat therewith;
(c) welding at least two clamps/hooks and reheating the bat in an open
hearth furnace to a temperature of around 1200°C, allowing the said
bat to soak for a period varying between 1 and 8 hours, depending on
the capacity and dimension of the hook;
(d) bending the bat obtained from step (c) with the help of a 'press-
jack' and claim working on the principle of stringed bow while the
said bat is still in plastic condition;
(e) cooling the forged and bend bat by allowing it to stand for 24 hours
and attain an equilibrium state;
(f) relieving bending stress in the bat from step (e) by gas cutting in
the bent locations and placing the same in an open-hearth furnace to
attain a plastic state;
(g) subjecting the bat from step (f) in plastic state to another round
of bending with the help of "pull-jack" after removal from the
furnace, followed by cooling to ambient temperature;
(h) back-bending the partially bent bat to impart a desired profile with
a "press-jack" and a suitable template conforming to the desired
dimensions of the hook in its final shape, size and configuration,
and

(i) normalizing, annealing, machining and polishing the hook in its
final form.
The subject invention also relates to an apparatus or system for making
durable, heavy duty shank-hooks, characterized in that the said system comprises
in combination -
i) a hammer-forging unit for converting a tested bloom into a bat;
ii) a "press-jack" unit for bending the forged bat to impart a
"0" - shape;
iii) a steel plate formed/shaped as per the drawing of the final product
serving as the template to determine and ensure different dimensions
of the product in the course of "heat";
iv) a pulling jack for shaping the bent body by closed bending to impart
a hook form;
(v) a plurality of holding means for shaping/developing the product
further and
(vi) a back-bending unit for imparting the desired shape to the shank
hook.
The pulling jack referred to above carries claims, which in turn are
attached/affixed to the two ends of the bat, which helps in exerting pull to
bring the hot portion of the forged bat into a bent shape.
In preparing hooks, including heavy duty hooks, in accordance with the

process of the present invention, the first important step in the selection of
proper raw material. One can select raw materials conforming to either British
Standard Class II or Indian Standard 20 mn2, the latter being preferred.
The raw material may be of the following different forms -
(i) ingots - its microstructure as per ASTM is 2-3 per sq.inch;
(ii) rolled slab - as per ASTM its microstructure stands at around
3-4 per sq.inch, and
(iii) hammer forged bat - when such bat is formed from a bloom following
hammer forging, the microstructure as per ASTM has a value of
around 6-8.
Taking into account the direction of microflow, in ingots there is no
specific direction due to coarse grain. In rolled slab, it flows in the direction
of rolling, but in the case of bloom-forged bat, when it is bent in the shape of
a hook, the microflow will follow the contour of the hook's body.
Such variation in the direction of microflow in the bloom-forged bat
results in enhancement of both strength and elasticity, rendering the hooks
capable of handling/lifting much greater quantum of load.
Before sending the bloom to hammer forging, the raw material is subjected
to both chemical and ultrasonic tests to detect deformities and microcracks, if
any. The bloom is sent for hammer forging and bat formation after it clears the
tests.
The approval and tested bloom is forged with a heavy steam hammer after

bringing the bloom to a plastic state by heating in an oil-fired furnace at
around 1200°C. After forging the bat from an oversized bloom, the grain structure
may be ascertained and conducting ultrasonic test thereof is a necessity. The
width and thickness of the forged bat are normally kept at dimensions in excess
of the final article, namely, hook, to accommodate shrinkage while bending and
also for relieving the bend stress.
After forming the bat by forging, two clamps/hooks are welded at two ends
of the forged bat which is then placed in an open hearth furnace and heated to
around 1200°C with hard coke. After soaking for a period varying between 1 and 8
hours, depending on the capacity and dimension of the hook, the bat is bent with
the help of a "press-jack" and chain working on the principle of a stringed bow
while the said bat is still in plastic condition. The bent and forged bat is
allowed to cool to ambient temperature for around 24 hours for further operation
and also to regain equilibrium.
The second phase of operation is initiated by relieving the bending stress
with the step of gas cutting. Thereafter the article was placed in aforesaid
furnace, heated to reach a plastic condition and then subjected to another round
of bending with the help of "pull-jack". The bent article is removed from the
furnace and allowed to cool to ambient temperature.
Finally the back bending of the article for imparting the final bent
profile is carried out by using a "press-jack" with a template conforming to the
desired dimensions of the hook in its final shape, size and configuration. The
hook thus formed is dressed/machined to remove rough edges and burrs and then
subjected to ultrasonic test to detect any flaw or crack(s) in the finished
product.

As a further step in forming the desired shank-hook, gas cutting is
carried out to set the press-jack to form the back of the end product and two
small holders/hooks are welded to the back side of the hook for facilitating
subsequent operations.
For imparting final desired shape to the shank-hook, the press jack unit
mounted on a base steel block is deployed along with two chains affixed to the
said small hooks to exert pressure for finally shaping the hook. These small
hooks are removed once the operations are over.
The approved finished product is sent for normalizing followed by
annealing, and the annealed product is despatched to customer after machining
and polishing as and when necessary.
The present invention will be more particularly illustrated by means of
the accompanying drawings wherein -
Fig.l shows the press jack unit for initiating the bending operation of
the forging bat.
Fig.2 shows the pulling jack unit for closing the two ends of the bat to
the shape of the shank hook.
Fig.3 shows the shank-hook carrying two small hooks welded in position for
facilitating final operation and also indicating locations where
curved portion of the shank-hook is formed by gas cutting in desired
locations and
Fig.4 shows formation of the end product by employing a bat-bending system
which is closely similar to press-jack system.

In Fig.1, (1) is the forging bat, usually hammer forged from 20 mn2 or as
per requirement of the customer tested bloom, (2) is the chain, (3) is the
'press-jack', (4) is the front attachment of block (popularly termed "jogan" in
Kolkata), (5) stands for hooks welded to the front and rear shanks of the bat and
(6) is the base block - like bar of piece of bloom (usually termed as "back
jogan") on which the "press-jack" unit is supported.
In Fig.2, (7) is the pulling-jack unit, and (1), (2) and (5) have the same
significance as stated above.
Referring to Fig.3, (5) shows the locations where small hooks are welded
for affixing chain(s) to exert pressure while effecting final back bending, (8)
indicates the position where gas cutting may be needed for imparting a desired
rounded shape to the shank hook.
In Fig.4, the apparatus set-up illustrates the final back-bending of the
shank-hook with press jack in which (1 ) shows the lip of the hook the formed
groove, (2),(3),(4), (5) and (6) have the same significance as given in Fig.l,
(9) is the original position of the shank and (10) is the new position of the
shank bent to a desired angle for arriving at the final product with desired
degree of accuracy.
As for the material of construction of the shank-hook, Class II or 20 mn2
or as per requirement of the customer tested blooms have been found to be
suitable and satisfactory, which can be subjected to bending and bringing to the
desired shape for arriving at heavy duty shank-hooks. It has been observed that
most acceptable starting (mother) material for any type of hook should be one
wherein percentages of P, S, Si and other impurities are comparatively lower in
comparison to general steel.
The tensile strength of best grade steel is expected not to exceed
46000 lbs/sq.in. Mild steel with about 0.15 percent C has a tensile strength

nearly double this amount. It has also been found that ductility and toughness
of wrought iron is greater than that of ordinary steel. As per the Indian
Standard, in 20 mn2 steel manganese is 1.30 to 1.70, Carbon is 0.16 to 0.24, and
silicon is 0.35 (max), which is considered to be the best material for hooks.
The designs of the different units of the apparatus or system are unique
and these were fabricated and assembled with utmost care. For making a shank-
hook capable of lifting a load in excess of 125 mT, a heavy duty "press-jack" is
needed to bend a hammer forged bat. The body materials for the "press jack" unit
was En 36, screw of En 36 and nut of En 24 or En 9. To ensure a smooth working,
a thrush bearing was placed between the nut and the body, and also in its screw's
locking system with the body in order to bend the hook's bat, its weight varying
between 100 kg and 6 mT.
As regards the "pull-jack" unit, the body was made of 20 mn2 for enhanced
elongation, screw of En 24 and nut of En 9. The back plate was of class IV, and
the hooks deployed had the same capacity as those in 'press-jack'. A thrush
bearing was provided between the nut and back plate.
Differing capacities of press jacks, chains, shackles, pull-jack etc.
were fabricated for handling heavy duty and super heavy duty works, e.g. from
5 mT - 32 mT, from 40 mT - 63 mT and from 80 mT - 125 mT, respectively.
Varying nature and dimensions of base block placed horizontally in the
set-up of the apparatus may be formed from cut-pieces of billet or bloom, such
as, for example -
(i) base block of billets or blooms measuring -
(a) 4" x 4" x 3' - are normally used for 5 tons - 25 tons attachments
considered to be "light duty" in a set;

(b) 5" x 5" x 4'
or
6" x 6" x 5' - are normally used for 30 tons - 80 tons attachments
considered to be "medium duty" in a set;
(c) 12" x 14" x 6' - are normally used for 100 tons - 125 tons
attachments considered to be "heavy duty" in a set;
Satisfactory performance of the hook will depend largely on the nature of
steel, wherein percentage of phosphorus, sulphur, silicon and other impurities
are comparatively low in comparison to ordinary steel. The tensile strength of
good quality steel should not exceed 46000 lbs/sq.in. Mild steel with around
0.15% carbon has tensile strength nearly double this value. However, ductility
and toughness of wrought iron have been found to be greater than ordinary steel.
British Standard (B.S.) stipulates that steel conforming to Class II and
En 3A are preferred materials for use in a hook, an approximate composition of
which is given below :

As steel conforming to British Standard were although readily available
in India, but Indian Standard Institution stepped in and after prolonged
experimentation laid down an Indian Standard, IS-4367-1967, and concluded that
20 mn2 is the preferred metarial for use in a hook which should have the
undernoted composition :


From the foregoing analysis it may be noted that percentages of manganese and
silicon are higher in 20 mn2 in comparison to British Standards, but it shows
better results of elasticity, tensile strength, breaking load and toughness in
comparision to B.S. materials.
A few other parameters to be taken into consideration for evaluating the
performance of a hook are given below :
(i) Lifting Capacity Cp : Maximum value of the mass which the
hook is authorized to support in general service when its axis of
traction is vertical.
(ii) Proof load Fc : Force applied in a static 'Tensile
Test' which the hook shall sustain without showing permanent
deformation or other visible defects.
(iiij Grade of hook : The grade of hook is determined by
the mechanical properties of the finished hook and not simply by the
strength of the materials. Each grade is identified by a letter in
the series M, P, S, T, V.
For grade 'M' the mean stress at the specified minimum breaking load is
400 N/mm2, for grade 'S' 630 N/mm2, for grade 'T' 800 N/mm2, for grade 'V'
1000 N/mm2, (as per I.S. 7847-1975)


In the case of heavy duty, the parameters will have to be changed from light to
heavy capacity as per IS - 6294-1971, the figures for which are given below :

But hooks produced by forged bat-bending process envolved in accordance
with this invention have been found to work far in excess of the proof load as
laid down by Indian Standards without compromising or forsaking safety factors.
Hooks made in accordance with the process of this invention, suppose 125 tons,
are capable of lifting/handling loads in excess of 250 mT without a single

instance of failure, repture, cracks or breakage.
Next, the undernoted tables give experimental figures for (i) time
required for final back bending of shank hook, (ii) normalizing temperature,
(iii) annealing temperature and (iv) period of soaking, depending on the
capacity (tonnage) of the hook produced by the process of this invention.
Table I
Time needed to effect bending of forged bats heated to 1200°C to attain a plastic
state.

As discussed earlier, hooks bent to attain the desired shape, size
and configuration are subjected to the steps of 'normalizing', followed by
'annealing'. For effecting normalizing the hook is slowly heated in an
electrical furnace to a temperature of around 50°C, held for a predetermined
period depending upon the capacity of the hook and then removed from furnace
and cooled under ambient conditions.
The following data show the relationship in a tabular form.


Following 'normalizing' the hook is 'annealed' by reheating in an
electrical furnace to a temperature of around 50°C for a predetermined
"soaking time", followed by slow cooling by allowing the hook to remain in
the furnace in a closed condition after being switched off it cools down to
ambient. The relationship between 'capacity' and 'soaking time' has been
shown above in Table II.
The hook normalized and annealed as described above is thereafter taken
for machining and polishing, usually by grinding, so as to arrive at a final form
and then sent for a "load test" before being despatched to the customer.
Contrary to the specifications laid down by Indian Standards Institution
from time to time, "the hammer-forged, bat-bending hooks" prepared in accordance
with the present invention exhibit normal working load far exceeding the values
recommended for conventional heavy duty hooks, as will be seen from the data
given below in Table III :


In point of fact, with a heavy duty shank hook made by the process of this
invention no breakage or deformity was observed even with five fold of working
load enhancement in the destructive load, thereby asserting safety of the
aforementioned shank hooks.
The characteristic features and consequent advantages of the shank hooks
made by the process of this invention may be summarised as follows :
(i) The hooks are of considerable strength and power, gaining enhanced
stability and are not easily breakable.
(ii) Elasticity is more as evidenced in the course of bending step and
grain structure is lot more compact to the tune of 6-8 ASTM.

(iii) The hooks are safe, reliable and of long life, rendering them highly
cost effective, which opens up a distinct possibility of an export
market by exploting the technology in countries abroad.
(iv) The novel apparatus or system of this invention and components
thereof can be fabricated from indigenously available raw
materials, and does not need any imported machineries or steel.
(v) The apparatus or system of this invention is extremely cost
effective and the procedure is environment - friendly.
Additional modifications and improvements of the present invention will be
apparent to those skilled in the art, and a preferred embosiment of the invention
has been disclosed by way of illustration. Thus, the particular combination of
components, parts and/or units described and illustrated herein is intended to
represent only one embodiment of the subject invention, and is not intended to
serve as limitations of alternative devices without departing from the spirit
and scope of the invention as recited hereinbefore.
Having described the inventionin detail with particular reference to the
illustrative drawings, it will now be more specifically defined by claims
appended hereafter.

We claim :
1. A process for making durable, heavy duty shank-hooks of varying capacities,
characterised in that the said process comprises -
(a) selecting a bloom and subjecting it to close scrutiny to detect any
deformities, microcracks and/or blow holes;
(b) forging the bloom with a heavy duty steam hammer after bringing the said
bloom to a plkastic state by heating and forming a bat therewith;
(c) welding at least two clamps/hooks and reheating the bat in an open hearth
furnace to a temperature of around 1200°C, allowing the said bat to soak
for a period varying between 1 and 8 hours, depending on the capacity and
dimension of the hook;
(d) bending the bat obtained from step (c) with the help of a 'press-jack' and
claim working on the principle of stringed bow while the said bat is still
in plastic condition;
(e) cooling the forged and bend bat by allowing it to stand for 24 hours and
attain an equilibrium state;
(f) relieving bending stress in the bat from step (e) by gas cutting in the
bent locations and placing the same in an open-hearth furnace to attain
a plastic state;
(g) subjecting the bat from step (f) in plastic state to another round of
bending with the help of "pull-jack" after removal from the furnace,
followed by cooling to ambient temperature;

(h) back-bending the partially bent bat to impart a desired profile with a
"press-jack" and a suitable template conforming to the desired dimensions
of the hook in its final shape, size and configuration, and
(i) normalizing, annealing, machining and polishing the hook in its final
form.
2. A process as claimed in Claim 1, wherein the selected bloom is subjected
to chemical, ultrasonic and/or radiographic tests to detect any defect(s) present
therein.
3. A process as claimed in Claims 1 and 2, wherein for effecting 'normalization',
the hook is slowly heated in an electrical furnace to a temperature of around
50°C, held there for a predetermined period depnding upon the capacity of the
hook, removed from furnace and cooled under ambient conditions.
4. A process as claimed in Claims 1 and 3, wherein 'annealing' of the hook
following normilization is effected by heating the normalized hook in an electrical
furnace to a temperature of around 50°C for a predetermined 'soaking time',
followed by slow cooling effected by allowing the hook to remain in the furnace
in a closed condition after being switched off till it attains the ambient
temperature.
5. A process for making durable, heavy duty shank-hooks, substantially as
hereinbefore described with particular reference to the accompanying drawings.
6. An apparatus or system for making durable, heavy duty shank-hooks,
characterized in that the said system comprises in combination -
(i) a hammer-forging unit for convering a tested bloom into a bat (1);

(ii) a "press-jack" unit (3] for bending the forged bat to impart a "U" - shape;
(iii) a steel plate formed/shaped as per the drawing of the final product
serving as the template to determine and ensure different dimensions of
the product in the course of "heat";
(iv) a pulling jack (7) for shaping the bent body by closed bending to impart
a hook form;.
(v) a plurality of holding means (2) for shaping/developing the product further
and
(vi) a back-bending unit (3) for imparting the desired shape to the shank hook.
7. An apparatus or system as claimed in Claim 6, wherein the holding means (2)
are hooks welded to the body of the itself for facilitating progressive shaping
of the bat to a shank-hook by utilizing said "press-jack" and "pulling jack".
8. An apparatus or system for making durable, heavy duty shank-hooks,
substantially as hereinbefore described and particularly illustrated by means of
the accompanying drawings.

Heretofore heavy duty hooks were made either by cutting iron
slab directly for imparting the shape of a hook or by welding metal pieces and
cutting to shape. A subsequent procedure adopted forging of the shank portion of
a T- shaped iron slab, following cutting of the body to attain hook-shape.
None of the above procedures could produce shank hooks capable of
lifting loads in excess of 150 tons and those in use ran the risk of rupture with
inherent danger of injury or even death of workmen.
The present invention attempts to overcome the prior art drawbacks
and provides an apparatus of system as claimed in Claim 6, wherein the holding
means (2) are hooks welded to the body of the itself for facilitating progressive
shaping of the bat to a shank-hook by utilizing said "press-jack" and "pulling
jack".
This invention also concerns a process for making such heavy duty
shank hooks.