Note: Descriptions are shown in the official language in which they were submitted.
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This application is a divisional o~ S.N. 246,670
~iled 26 February 1976 and is directed to an improved tong-and~
bit combination while the parent application is directed to ~-~
an improved bit and a specific tong-and-bit combinat~on.
This invention relates to improved ~its for ingot
tongs, to improved tong-and-bit combinations, and to an
mproved method o~ handling ingots to increase bit li~e, `
Conventional practice in~handling and transporting
metal ingots, which weigh several tons and may be at elevated
temperatures, is to engage the ingot with tongs carried by
a suitable crane. The tongs have opposed~relatively movable
arms which carry ~its for biting into the side ~aces of the
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ingot and thus gripping and supporting the ingot. Usually bits
are formed of steel, such as AISI 1030 and 4140, and have ~-~
shanks fixed in bores in the tong arms, sometimes within `~
bushings inserted in the ;
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bores. the most c~omron way of fastenincJ a bi-t to a tong arm is by use of a
pin inserted through a transverse hole in the shank the outside faoe of the
arm. The bit has a wedge-shaped or conical point at its inside end, the apex
angle of which most aomronly is less than a right angle.
~its used heretofore have been short-lived, and normally must be
replaced after each turn. A steel bit should be water-oooled after each ingot
is carried, or its life is even shorter. Use of a pin to fasten the bit to the
arm necessitates that the bit shank protrude beyond the outside face of the
arm. A prDtruding shank may strike refractory walls of a soaking pit in which
the ingot is heated and damage these walls. There has been no provision for
adjusting the distance by which the point protrudes fram the inside face of
the arm for handling ingots of different sizes. The indentations left in ingot
surfaces by relatively sharp pointed bits may cause defects which must be
removed by scarfing or machining. The bit point wears almost exclusively at
its upper surface, but there is no provision for rotating the bit and thus -~
distributing the wear.
The present mvèntion provides an improved bit and improved tong-and-
bit combinations which overcame the foregoing disadvantages and greatly
prolong bit life. The present invention particularly provides improv0d tong-
and-bit combinations in which the bit can rotate relative to the tong arm to
distribute wear around the circumference of the point.
mus, in one aspect, the invention provides a bit for ingot tongs, the
bit comprising a cylindrical head, a single blunt conical point, and a cylindri-cal, or slightly tapered, shank all formed as an integral casting, the shank
having an end opposite its head, a transverse hole and lengthwise grooves in itsouter surface extending fram the ends of the hole to the end of the shank, the
hole being adapted to receive a ~d and the grooves to receive bent portions of
the rod to serve as fastening means for the bit.
In apother aspect the invention provides in combination, a tong arm,
a bit~ and næzn~ fastening the bit to the tong arm; the tong arm having a recess
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in its outside face and a kore extendiny frcm the bottam of the reoess to the
inside face; the bit camprising a cylindrical head, a single, blunt, conical
point, and a cylindrical or slightly tapered shank all formed as an i~tegral
casting, the shank having a transverse hole and lenythwise gmoves in its
outer surfaoe extending from the ends of the hole to its outside end; the
fastem ng means comprising a bushing fixed in the bore and rotatably receiv-
ing the shank, a rod bent to U-shape received in the hole and the grooves, a
retainer plate overlying the outside end of the bushing and having holes
through which the rod being bent flat against the retainer plate, and at
least one washer interposed between the inside end of the bushing and the
head; the retainer plate and the bent end portions of the rod being confined ;~
within the recess to avoid protrusions fmm the outside fa oe of the tong arm;
the washer permitting ad~ustment in the distance by which the point protrudes
from the inside face of the tong arm.
In yet another aspect the mvention provides in cc~binatiGn a bit, a
tong arm, and means fasteniny said bit to said tony arm; the bit camprisiny a
cylindrical head, a single blunt conical point, and a cylindrical or slightly
tapered shank all formed as an integral casting; the tong anm having inside
and outside faces and a bore extending therethrough; the fastening means
cGmprising a bushing fixed within the bore and receiving the shank, and
means on the shank confined between the faces of the tong arm retaining the
shank within the bushing; the head and the poin~ protruding from the inside
face of the tong arm; the shank being rotatable within the bushiny, whereby
wear on the point is distributed ar~und the circumference.
In the drawings:
Figure 1 is a partly diagrammatic side elevational view of an ingot
and tongs engaged therewith.
Figure 2 is a vertical sectional view on a larger scale of the lower
end of a tong anm and bit constnucted in accordance with our invention;
Figure 3 is an elevational view from the left of Figure 2;
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Figure 4 is a vertical sectional view similar to Fi~ure 2,
but showing a modification;
Figure 5 is a side elevational view of a tong arm and bit
illustrating a procedure by which we determine when our bit has
worn excessively; and
Figure 6 is a diagrammatic view of an ingot and tongs
illustrating our handling method
Figure 1 shows a conventional ingot 10 and tongs 12 for
handling and transporting the ingot. The tongs include a pair
of opposed relatively movable arms 13 and a mechanism 14,
not shown in detail, for operating the arms. The arms are
equipped with bits 15 constructed in accordance with our
invention for engaging the side faces of the ingot. Our
bits, of course, are not limited to use with tongs of the
particular construction illustrated.
As Figures 2 and 3 show, our bit 15 includes a cylindrical
head 18, a conical point 19, and a cylindrical or slightly
tapered shank 20 all formed as an integral casting. Although
the bit can be of one of the usual steel compositions, we
prefer to use a more durable metal, preferably a nickel alloy
or a cobalt alloy. The best material we have found is "Inconnel
713C", which is a nickel alloy containing nominally 12.5%
chromium, 4.2~ molybdenum, 6.1% aluminum and small amounts
of titanium and zirconium. The tong arm 13 has a recess 21 in -~
its outside face and a bore 22 which extends from the bottom of
the recess to the inside face. Preferably the bore 22 has a
counterbore 23 at the inside face and receives a flanged bushing
24, which is press-fi~ted or otherwise immovably fixed in the
arm. Preferably also the bushing has an external circumferential
groove at the bottom of the recess 21 in which we insert a retain-
er ring 25. We interpose one or more washers 26 between the bit
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head 18 and the inside end of the bushiny. The bushing and
washer conveniently are of the same metal, such as 4140 steel,
but in use the washer, rather than the bushing, is exposed to
the heat of the ingot and absorbs the mo~t wear. Consequentl~
we find it seldom is necessary to replace the bushing, which is
more difficult to remove and replace than the washer.
The bit shank 20 has a transverse hole 29, preferably ~ -
located along a diameter near its outside end, and a pair of
opposed lengthwise grooves 30, which extend along its outer face
from the ends of the hole to-the outside end of the shank. ~
Before inserting the bit in the bushing 24, we insert a rod 31 -
through hole 29 and bend the rod to a U-shape so that it -
lies within grooves 30. After inserting the bit, we place -
a retainer plate 32 over the outside end of the bushing axially
spaced from the end of the shank 20. Plate 32 has holes 33 posi-
tioned to receive the two legs of rod 31. We complete the ass- ~
embly by bending the end of the rod flat against the outside face ~ -
of plate 32 and tack-welding them. The plate and rod ends
lie entirely within recess 21 of the tong arm 13 and thus do not
protrude to a position where they can strike and damage re-
fractories. We can add more washers 26 or use washers of
different thickness to adjust the distance by which the point
19 protrudes from the inside face of the tong arm. The point
should protrude farther when the tongs are used for handling
smaller ingots. Also as the point wears and is dressed, as
hereinafter explained, we may add washers to compensate.
Figure 4 shows a modification in the fastening
means which we utilize for mounting our bit on a tong arm 36
lacking a recess in its outside face. The parts are similarly
constructed, except that we rely on the press-fit alone to hold
a bushing 37 within a bore 38 in the tong arm. The retainer
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plate and rod lie within the bore, thus ~avoiding any protrusion
from the outside face of the arm. This modification is par-
ticularly useful for applying our bit to an existing tong arm
which is not constructed especially for our bit.
Initially the end of point 19 is rounded on a radius
of at least about one-half inch and preferably has an apex
angle greater than a right angle, for example about 100.
Although we do not claim it as our invention, our experience
has shown that a point thus proportioned penetrates the sur-
faces of an ingot to the extent necessary to grip and support the -
ingot, but the indentations which it leaves do not ordinarily
cause defects. As the point wears in use, it becomes progress-
ively blunter; that is, the radius progressively increases. We
have observed that a bit is still serv'ceable when the radius
of the point increases to about 1-3/8 inch, but that it no
longer is serviceable when the radius ~e~ches about 1-5~8 i~nch. `~
Preferably we use a gauge 41 constructed as shown in
Figure 5 to determine whether a bit is still serviceable
after a period of use. The gauge has a central contact area 42
and two side contact areas 43. We place the gauge over the
point as shown in Figure 5. If the central contact area 42 ~ `
makes contact with the apex of the point, the bit is serviceable~
If the side contact areas 43 make contact with the conical sides
of the point and the central contact area fails to make contact
with the apex, as shown in Figure 5, the bit no ionger is service-
able. Preferably the head 18 of our bit has an axial length
sufficient that the point can be dressed about four times
after it has become too blunt by the measurement described. As
the head becomes thinner, washers 26 can be added or a thicker
washer used to return the point to its original position.
Figure 6 illustrates our handling method. The ~hank 20
of the bit is freely rotatable in the bushing 24. When the
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tongs 12 pick up an ingot 10, they normally contact the ingot
slightly off center. In Figure 6 the distance x from the point
of engagement to the left side is slightly greater than the -~
distance y to the right side. Consequently the ingot assumes
a position slightly askew from upright. When the tongs set
the ingot on a surface 44, the ingot returns to an upright ~ ;
position and rotates clockwise through a small arc. The bits
15 rotate with the ingot. Thus they move to a position in
which a fresh area of the point 19 faces upwardly. The bit
la also tends to rotate whenever the point scrapes across the sur~
face of an ingot as the tongs pick up or disengage the ingot.
With repeated use, all areas of the point eventually face
upwardly in turn, whereby the point wears uniformly around its
full circumference. We need not water-cool the bit after
each use.
From the foregoing description, it is seen that our
invention affords an improved bit and tong-and-bit combination
which greatly prolong the useful life of a bit. This
benefit is achieved by forming the bit of a more durable metal,
2Q by distributing wear around the circumference of the point,
and by proportioning the head and point so that the point can
be repeatedly dressed after it becomes too blunt. Our ~
combination also avoids any protrusion from the outside -- -
- faces of the tong arms, and makes it possible to adjust the dis-
tance by which the point protrudes from the inside faces.
Our handling method assures that the bit rotates with each use
to distribute wear. Although the preferred nickel alloy of
which we form the bit is substantially more costly then steel,
our invention reduces the total cost for bits many fold.
