Improvements in Cycle Chain Rivets, and in the Process of . Making same.
Year: 1897

page_text: Date of Application, 23rd Nov., 1897-Accepted, 2nd Apr., 1898
COMPLETE SPECIFICATION.
Improvements in Cycle Chain Rivets, and in the Process of .
Making same.
I, HUMPHREY HARRINGTON, of No. 1704, Ash Street, in the City of Indianapolis,
County of Marion and State of Indiana, U.S.A., Mechanical Engineer, do hereby
declare the nature of this invention to be as follows:-
The wire froin which the rivets or studs are manufactured is of soft iron or low
steel. It is treated by straightening and machining to reduce the portions which are
to serve as the necks, and to cut off the rivets to the proper lengths. I then apply
on each reduced end a close-fitting cap of copper, and introduce the rivets thus
capped, into a carbon bath composed preferably of broken bone, and heat the whole
for such a period, say one hour, as will induce a moderately high steel over the
remaining surface. This gives a peculiar condition of the mid-length or body,―this
important main portion having an interior of low steel or soft iron, and a considerable
In this operation some of the caps
thickness at the surface of moderately high steel.
will become loosened and detached, and in order to secure uniformity in the final
riveting, I allow the whole to cool, and take off by hand or by agitation as with a
threshing machine and winnower, all the caps from the rivets and separate them.
The rivets thus prepared are subsequently placed in a tight case and the entire
surfaces of such nearly completed rivets are then treated by heating for a brief
period with a highly carbonizing chemical as cyanide of potassium or prussiate of
potash, after which the rivets are suddenly cooled in water or oil.
The rivets are of the ordinary form and appearance when completed, and may be
worked in all respects in the ordinary way, each with the body sufficiently longer than
the width of the block to relieve them from any pressure between the side plates,-
except that the operation of riveting or heading the ends after the parts of the chain
have been assembled, requires to be conducted with more vigor in consequence of the
hardness of a thin coating on the surface of the necks and ends. The chain when
completed appears in all respects like the ordinary chain.
The chain works the same as a chain made of iron or low steel except that it will
better endure wear by reason of the peculiar steel coating on the mid-length or body
of the rivet, having not only the coating of moderately high steel which is due to the
first, but also having the extreme outer portion of such coating still harder steel, due
to the later treatment with chemicals.
In the accompanying drawings
-
Figures 1 to 6 are central longitudinal sections through the same rivet at different
stages, some of the figures showing additional parts correspondingly sectioned.
Fig. 1 represents a rivet of soft iron or low steel before the commencement of my
treatment.
Fig. 2 shows the same after the caps have been applied.
Fig. 3 shows the same after the capped rivets have been exposed to heat with the
broken bone or other moderately carbonizing inmaterial.
Fig. 4 shows the same after that treatment is completed and the caps have been
removed.

page_text: Fig. 5 shows the same after the second carbonizing. The rivet is now completed.
Fig. 6 shows the same after the rivet has been brought into its proper relation to
the center block and to the side plates, and the ends have been riveted.
Figures 7 and 8 are central sections of the apparatus employed.
Fig. 7 is a section of the closed case in which the first carbonizing is
effected.
Fig. 8 is a section showing the vessel in which the second carbonizing is
effected.
Similar letters of reference indicate corresponding parts in all the figures where
they appear.
Referring to Figures 1, 2, 3, 4 and 5, A is the soft iron or low steel, and A' is a
moderate thickness on the exterior thereof, which has been raised to a moderately
steelified condition, capable of being considerably hardened by sudden cooling, but
not quite up to the condition of tool steel.
Figure 1 shows the partially manufactured rivet after its necks have been machined
down and the wire cut off into proper lengths for rivets.
These
Figure 2 shows a rivet after its ends have been defended. There must be previously
provided a liberal quantity of caps B of a sufficient length to match on the necks.
I have in my experiments used such caps as carry the fulminate in fire arms.
empty copper caps are practically proof against the penetration of carbon, and
although carbon will creep somewhat under the cap so that a high steel condition will
obtain at the junction of the neck with the body, gradually weakening for some little
distance out on the neck, the ends will be soft. I stratify the rivets thus capped
with broken bone or other moderately carbonizing material in closed vessels and
expose to a red heat for about an hour.
A quantity of the rivets thus far advanced are next placed in a suitable vessel M,
(see Fig. 8) with cyanide of potassium or prussiate of potash, and heated to a cherry
red, when they are withdrawn from the fire and poured into a tank of water or oil,
not shown. The useful effect of the treatment with the chemical is to raise the
steelified condition on the surface of the body still higher. The highly carbonized
condition thus induced does not extend inward to the same depth as the more mode-
rately carbonized coating A¹. This thin high steel coating over the whole surface is
marked A2, (see Figures 5 and 6). The rivet retains its original soft condition in
the interior and has a fairly hardened condition on the exterior of the body to a
considerable depth with the further quality that a thin portion A on the exterior of
the body is still more hard, because of the higher condition of the steel induced by
the chemical, and will therefore allow the rivet to wear longer.
Figure 5 shows the rivet after the thin coating of very high steel has been induced
over the whole surface, and before the riveting.
Figure 6 shows the same after the parts have been assembled and the heading of
the rivet has been effected. In the healing operation the soft material in the
interior is spread at the ends carrying with it the intensely hard but very thin surface
coating A, which hard coating is a slight but only slight obstacle to the riveting
process.
The apparatus for effecting the first surface carbonizing is as follows:-
Referring to Figure 7,
D is a cylindrical case of cast iron screw-threaded to receive a cap at each end.
One cap D¹, may be permanently set; the other, De, should be removable. Both are
made to fit with tolerable tightness.
To properly charge the case D, it is set upright and the upper cover D² removed;
the properly mixed rivets and broken bone are poured in until the case is nearly
filled with the materials in the loose condition. The cover D2 being applied, atten-
tion may be given to the next case and so on.
These cases are put in the highly heated oven or furnace and rolled a little from
time to time during the one hour or longer which it is found expedient to subject
them to this treatment; the cases are then removed and preferably piled together

page_text: and covered with ashes or other non-conductor, so that the cooling will be slow; but
if occasion arises for rapid work, the cap D can be removel and the cases emptied
and re-charged while hot. The rivets are now in the condition of being steelified
moderately to a considerable depth over the entire boly and to a less thickness a
short distance out on each neck but with the ends entirely soft. The portions which
have been steelified are not as high steel as is desired, and the object of the further
treatment is to raise a portion of the metal, that on the extreme outer surface of the
body, to a still higher condition.
The vessel M is used for the second carbonizing. See Figure 8. A cover N is
fitted on the vessel by a hinge N₁, and secured by a swinging catch P, hinged to the
cover at the point P'; and engaging under a lip or flange M on the vessel. This
cover allows the vessel to be shaken to facilitate the distribution of the chemical
among the rivets, and prevents the escape of the fumes which would otherwise be
annoying to the workmen, and are somewhat poisonous. With this hinged cover
and the fastening therefor, the quantity of chemical supplied for a given quantity of
rivets may be accuratety determined beforehand, and the heat of the vessel after one
treatment is over, may be utilized, putting a hand-full of cold rivets into the open
vessel, throwing the chemical upon those cold rivets and rapidly closing and securing
the cover. In such mode of operating the vessel may be agitated to effect the
thorough distribution of the chemical and the rivets, and they may be allowed to
remain for a longer period until practically the whole of the carbonizing effect of the
chemical is exhausted. This contributes to ensure a uniformity of thickness of the
high steel coating induced by the chemical. The opening of the apparatus is easy,
requiring simply a slight blow on the beveled under face of the locking catch P, to
liberate it and allow the vessel to be inverted and emptied.
The treatment with the chemical in the vessel M has the objectionable effect to
also coat the reduced necks and the offsets or shoulders at the junctions of the bodies
with the necks, and also the circular ends of the necks;-all are encumbered with a
thin coating of high steel, which, in the operation of sudden cooling to which it is
subjected, becomes hardened steel. But the thickness of this very high steel coating
is so slight that the disadvantage due to the hardness of the ends is of little
importance. Practice will determine for how long a period the operation should be
conducted. It should be such as to add appreciably to the hardness of the surface of
the body portion, and yet not be continued so long as to make an impracticable
thickness of hardened high steel on the ends which have to be subsequently distorted
by riveting or heading.
Modifications may be made without departing from the principle or sacrificing the
advantages of the invention. The first surface carbonizing may be carried to a
greater depth, but it is important not to have so thick a coating of steel on the necks,
and especially on the ends thereof, either from the first or the second carbonizing, as
will when the coating is hardened, offer serious difficulty in the riveting operation.
The joint between the hinged cover N and the main vessel M, in which the second.
carbonizing is effected, may be made loose and closed by a luting of soft clay.
It is preferable to effect the entire second carbonizing rapidly, as it conduces to
make the surface coating of high steel properly thin.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, what I claim is :-
1. In the process of manufacturing rivets for pitch-chains, first, turning down the
reduced necks and cutting off the rivets; second, covering tightly the reduced ends
and necks; third, carbonizing mildly the rema.ning surface; fourth, carbonizing
highly a thin coating over the entire surface of ti fully shaped rivets; and, fifth,
hardening by sudden cooling from a red heat, allustantially as herein specified.
2. A rivet for bicycle chains having a body and reduced ends, and composed of a
core of rivetable metal, a very hard surface layer over the body aud ends, and a layer
of intermediate hardness on the body between said core and surface layer said

page_text: intermediate layer being absent wholly or in large part from the reduced ends of the
rivet, substantially as described.
Dated don
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