Improvements in the Manufacture of Hollow Soft Rubber Articles.
Year: 1895

page_text: Date of Application, 17th Dec., 1895-Accepted, 8th Feb., 1896
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Hollow Soft Rubber
Articles.
We, HENRY GOODRICH WOLCOTT and JOHN PHILIP RIDER, both of
Fishkill Landing, County of Dutchess, State of New York, United States of
America, Gentlemen, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
This invention relates more especially to the manufacture of soft rubber balls,
although it will, from the following Specification, be clear to those skilled in the
art, that it may be applied with equal advantage to the manufacture of other
hollow articles of soft rubber or like material, and hence, while we shall confine our
description, to the process and mechanism employed by us in the manufacture of
rubber balls we do not wish to be limited to this particular manufacture.
In the manufacture of articles of this kind heretofore, it has been customary to
form the articles from sheet material or stock, usually soft-rubber in a more or
less unvulcanized state, but preferably containing the materials for facilitating
vulcanization and for giving the rubber a suitable body for the purposes intended.
The stock has usually been first cut into proper shape to form a ball, or take the
desired shape by inflation in which shape it is vulcanized in the ordinary manner.
When balls are being manufactured it is customary to place between the sheets a
small quantity of carbonate of ammonia or water, which when heated in the process
of vulcanization will form a gas to expand or inflate the article so as to fill the
vulcanizing mold and give a proper set to the stock as is well understood by those
skilled in the art. Such processes have usually been carried out by hand and while
machinery has been utilized to some extent the process where machinery was so
utilized has been very different and need not be dwelt upon berein further than
to say, that the articles are made in sections or halves adapted to be united after
being formed separately.
The old processes, such as above described are unsatisfactory because of the fact
that it is quite impossible to form the seams between the edges of the sheets
uniform in all instances, the result being that in the most economical manufacture,
approximately ten per cent. of the goods were lost. The defects in the seams can
only be seen after vulcanization by which process the material is greatly reduced
in value for manufacturing purposes.
We have in our present invention aimed to materially reduce the cost of pro-
duction, and overcome the objections in the old processes by reducing the number
of defective articles, and enabling the defects to be seen before the process of
vulcanization when the stock has not been materially injured for manufacturing
purposes. The process which we pursue is as follows: We first superpose sheets
of stock from which the ball is to be formed, clamp or confine the two sheets
together in a circular line, leaving the portion of the stock within the circle of
proper size to form a ball of the desired diameter, then while the sheets are so
clamped we inflate the portion within the confined area and while in its inflated
condition, sever the same from the sheets of stock by a pressure sufficient to cut
the stock and unite the edges of the confined portion.
In the condition in which the stock is worked the edges will be united auto-
geneously by pressure or if preferred, a cementing material may be placed between
the sheets of stock.

page_text: In the condition described the article may be handled and transferred to the
vulcanizing mold in the ordinary manner and should the seam uniting the sheet be
defective it will be known by the speedy collapse of the article before vulcanization.
The process contemplated by us involves the further step of so supporting the
stock during the process of inflation that the walls of the article shall be uniformly
stretched or attenuated and the seam between the sheets thickened to give
additional strength, which steps will be hereinafter more fully explained in
connection with the description of the mechanism which we have described for
carrying our invention into practice.
Referring to the accompanying drawings:
Figure 1 is a front elevation of a machine designed for carrying our invention
into practice.
Figure 2 is an elevation looking at the left hand side with portions broken away
to illustrate more clearly the parts concealed thereby.
Figure 3 is a similar view looking at the right hand side of the machine.
Figure 4 is a top plan view of one of the molds or dies.
Figure 5 is a vertical section through the same, and
Figure 6 is a sectional view of a modification.
Figure 7 is a sectional view of a ball made by our method.
Figure 8 is a sectional view through the dies when the dams have been brought
together and the ball inflated, but before the injector is withdrawn.
Figure 9 is an enlarged view of one side of the dies with the parts in the same
position.
Figure 10 is a view similar to Figure 9, with the injector withdrawn to the
position it occupies when pressure is reduced.
Figure 11 is a similar view with the dies brought together and the rubber stock
severed.
Figures 12 and 13 are detail elevations showing the mechanism for operating the
anvil locking bolts, Figure 12 showing the dies and heads opened widely and
Figure 13 as the dies separate and the inclines in engagement with the cranks to
withdraw the bolts and allow the anvils to advance and discharge the balls.
Figure 14 is an elevation of the valve controlling the air pressure.
Figure 15 is a view of a portion of Figure 2 drawn to an enlarged scale.
Like letters of reference in the several figures indicate the same parts.
The machine illustrated is designed for the formation of a series of balls at each
operation, but it will be understood that the number formed at one operation is
inmaterial. The letter A indicates the frame of the machine having at the top
ways B, for a sliding head B₁ adapted to be moved vertically by means of the
connecting rods B' extending down on each side and operated by cranks B on the
ends of a shaft B extending transversely of the machine. This shaft is driven
intermittingly as will be presently described, the motion being derived through the
train of gears C C C C³, the latter being mounted on a shaft C' driven by fast
and loose pulleys C.
In the lower face of the sliding head B¹ there is mounted a series of concave
molds or dies E and immediately below them on the cross table or support F is a
corresponding series of dies E¹, said upper and lower dies registering with each
other and adapted when the sliding head is brought down, to come together with
sufficient force to sever the stock located between them.
Around the edges of each of the dies there is located a dam or clamp, the
clamps on the upper and lower dies being adapted to come together in advance of
the edges of the dies themselves, and to yield slightly or to a sufficient degree to
allow the edges of the dies to come together. In the preferred construction these
clamps take the form of annular collars G sliding directly on the dies and having
their clamp faces held normally projected slightly beyond the edge of the dies by
means of relatively heavy springs G¹ as shown clearly in Figure 5.
In the operation of the machine it is designed as just stated that the clamps
shall come together in advance of the moids, and at the moment when the clamps

page_text: have gripped the stock firmnly we inflate the balls or the portion of the stock held
between the clamps by means of injectors, which latter, for convenience, are in the
form of relatively fine hollow needles H carried by a tube H' connected through a
flexible tube H with a source of pressure supply, and adapted through mechanical
connections to be presently described, to be advanced between the superposed
sheets of stock and between the lips of the clamps, the latter exerting sufficient
pressure to prevent the escape of air, but at the same time allowing the needle or
injector to be withdrawn without difficulty. The needles of the injectors preferably
enter the clamps at one side of the center or tangentially in order that the hole
left thereby may be more readily closed by the pressure of the clamps after the
needle is withdrawn.
The source of pressure supply is preferably a receiver formed by the framing of
the machine, which is all hollow and supplied through a pipe 18 by an air pump I
operated by a crank arm I' on the shaft c. A safety valve I2 is provided on the
hollow frame to guard against excess of pressure and a pressure gage 13 at the top
of the frame indicates to the operator the pressure existing at the instant of
inflation. To advance the injector carrying tube H¹ it is mounted to move in
ways Hat each side of the machine and is connected by a link H with a bell
crank H operated through a link H from a foot treadle H.
The process as carried out with the mechanism thus far described is as follows:
A sheet of rubber is laid on the lower dies and the injectors advanced so as to
project within the circle of the clamps, a small portion of carbonate of ammonia or
water being placed within the circle, and another sheet of rubber laid over the top
of the injectors. The sliding head is then caused, to descend until the two clamps
are pressed together with sufficient force to prevent the escape of air from within
the clamps, when pressure is admitted through the injectors, preferably by the
manipulation of a valve W at one end of the injector support. This forces the
portions of the sheets of rubber confined by the clamps in opposite directions
and fills the dies, giving the portions confined within the clamps a somewhat
spherical shape. When this has been done the injectors are withdrawn beyond
the edge of the clamps and the motion of the sliding head is completed the
pressure on the clamps increased and the edges of the dies or molds brought
together. The clamps prevent any of the material from flowing outward, and in
fact as they come together they force a portion of the material or stock inward
and consequently as none of the material can flow outward when the edges of the
dies approach, it is of necessity caused to flow inward and unites autogeneously
in the form of a relatively thick seam, the projection of which is on the inside of
the completed article, as shown clearly at S, Figure 7. The dies are brought
together with sufficient force to sever the two sheets of stock, and when the dies
are again separated, the articles may be removed and replaced in the ordinary
molds for vulcanization.
It is found in practical operation that the sheets of rubber or stock when inflated.
within the clamps and dies, will expaud more at the center or polar portions,
considering the point of union as the equator, the result being that these portions
of the article are made much thinner and when inflated after vulcanization will
cause the article to assume au ovoid shape. To prevent this, and secure a perfectly
equal attenuation or stretching of the stock throughout the whole area, we provide
a means for supporting that portion of the stock constituting the polar portions
while the zones nearer the center or line of union are expanded. By reference to
Figure 5 and Figures 8, 9, 10 and 11, it will be seen that each die is provided with
a central anvil K preferably movable and held advanced by a spring K' to the
position shown in dotted lines.
When pressure is admitted between the sheets of material, it causes the portions
of the material between the edges of the anvil and edges of the die to be first
expanded then, as the pressure increases, or the portions mentioned have become
expanded sufficiently, the anvils will be forced back and the polar portions will
be expanded, the anvil retreating and forming the bottom portions of the dies.

page_text: The anvils are prevented from advancing and again compressing the articles when
the pressure is relieved by bolts k working through the sides of the dies and
adapted to engage a shoulder k¹ in the body of the anvil when the latter are
retracted.
These bolts are adapted to be released by being connected with cranks kon
shafts having operating cranks *, Figures 2 and 3, and Figures 12 and 13, with
which inclines kk on the frame and sliding head respectively engage. These
inclines engage the releasing cranks as the sliding head moves upward and after
it is sufficiently separated to allow the articles to be removed, the result being that
the anvils are held retracted during the time the articles are being completed, but
are advanced to disengage the formed article and are ready for the formation of
other articles as soon as the dies are separated.
It has been further developed in the practical operation of the machine and in
the practice of the method set forth, that if a sufficient pressure is admitted
between the sheets held by the clamps to force the same outward and give a
proper attenuation of the walls and this pressure is maintained until the dies are
opened, it is apt to cause such an expansion as would either distort or endanger
the article by opening or weakening the seams or else cause it to more than
fill the vulcanizing mold or fill the same irregularly, and with a view to over-
coming this, we first admit sufficient pressure to properly expand the article
and then reduce the pressure leaving only sufficient pressure to give the articles
an approximately spherical shape, relying on the usual ammonia or equivalent to
give the necessary expansion or inflation during vulcanization. For this purpose
the valve controlling the admission of pressure to the injectors is made in the
form of a pressure reducing valve and in operation after pressure has been
admitted to the injectors a reverse motion of the valve cuts off the pressure
supply and opens the injectors to the atmosphere through the pressure reducing
valve, which being set at the proper point will allow the pressure in the several
articles to instantly drop the air flowing back through the injectors.
The movements of the injectors may be controlled so as to prevent any
possibility of their being caught by the edges of the dies or clamps through
automatic mechanism, which will, after pressure is admitted, first withdraw the
injectors just beyond the edges of the clamps, without, however, withdrawing them
from the opening formed by then between the sheets of rubber so as to prevent the
pressure from escaping until the clamps and edges of the dies are brought together.
For this purpose the injectors are preferably retracted by spring pressure, a
spring L being provided at one end for this purpose, and a pawl L' co-operating
with notches on a segment L² serves to hold the injectors advanced. The
notches are so positioned that one of them will co-operate with the pawl when the
injectors are fully advanced, the second when the injectors are withdrawn just
beyond the edge of the clamps and the third when the injectors are fully with-
drawn. The pawl is released by pins L³ carried by a gear wheel L* journaled ou
the frame and driven by a pinion L' on the shaft c of the main train. The
pins L L are so positioned that as the wheel L' is rotated one will engage the
pawl at the proper instant to allow the injectors to retreat to the proper point
shown in Figure 10 just before the final manipulation of the pressure valve and
when this has been done and the clamps brought together the second will engage
the pawl and allow the injectors to fully retreat out of the way of the manipulation
of the stock.
By reference to Figures 3 and 14, it will be seen that the valve is automatically
operated to cut off the pressure and open communication, through the pressure
regulator, with the external air. The valve (W) is made in the form of a three
way cock controlled by the arm W adapted to be elevated by spring pressure and
depressed by a foot W carried by the upper head. When the upper head
descends to the position shown in Figure 9 the foot and valve occupy the position
shown in full lines Figure 14, with air pressure from the reservoir open to the
needles and when the needles are retracted to the position shown in Figure 10 the.

page_text: valve being on the needle carrying bar moves back to the position shown in dotted
lines Figure 14 the arm We slips off the foot W and the valve is shifted to cut off
the pressure and open the needles to the external air through the pressure
regulating valve W. This latter is of any ordinary construction and needs no
special description.
As before intimated, it is preferable to have the sliding head operated inter-
mittingly and if reference be had to Figures 2, 3 and 15 it will be seen that on the
shaft B we mount rigidly a disk M having teeth m and the gear wheel C is
provided on one of its spokes with a pawl N adapted to engage with said teeth m
locking the gear wheel and shaft for simultaneous rotation. This pawl is held in
engagement with the teeth only during a portion of each revolution of the gear
wheel, and consequently, operates the sliding head during only a portion of such
movement. The mechanism for holding the pawl in engagement consists of a
curved guide O adjustably mounted on a circular or rim-like portion O' of the
frame through the medium of slots and bolts o and preferably extends somewhat
more than half way around the shaft. The end of the pawl rides inside of this
curved guide O as shown in Figure 15 (dotted lines on the left) being thereby held
in engagement with the disk, but when the pawl has advanced beyond the guide it
yields or turns back and releases the disk. The pawl remains out of operation until
its rear end strikes the rounded end of the curved guide as shown in dotted lines on
the right in Figure 15 when it is again moved into operative position and will
engage the lower tooth.
The unlocking or releasing of the crank shaft and main gear takes place twice
during one movement of the sliding head. The lower intermission takes place the
instant the clamps first bite on the rubber. The time of intermission is sufficient
to inflate the ball and subsequently to allow the surplus air to escape by the
valve.
The upper intermission takes place when the head is near the extreme upper limit
of its motion and affords the operator time to remove the balls, strip off the surplus
rubber remaining on the clamps and place fresh sheets in position upon the clamps
for subsequent operation.
Obviously the speed of the machine determines the length of the intermission,
but it is to be noted that no intermission is necessary if the machine is to be run
slowly and furthermore, if so desired, any of the ordinary mechanical expedients for
reducing the motion periodically may be employed or the whole mechanism may be
stopped periodically and again thrown into operation manually by any of the
ordinary well known means.
The particular form of dam or clamp for preventing the outward flow of the stock
may be varied if so desired, and in fact elastic clamps such as rubber rings P,
Figure 6, might be employed to good advantage.
To secure a stronger seam we may bevel the edges of the dies as in Figures 9, 10
and 11 or said edges may have annular concavities such as Q, Figure 6, which serve
to grip portions of the respective sheets between them and subject the same to
excessive pressure, thereby securing a perfect welding or autogeneous union of the
edges on the outer side which in connection with the thickening and flowing
together of the material at the junction makes it even more certain that a perfect
seam shall be secured.
Obviously where balls or other articles are to be manufactured for inflation after
vulcanization, the sections of stock placed within the dies are provided with soft
rubber valves or equivalent devices and the balls or articles formed in the
ordinary manner. So too, it will be understood that while we have described our
invention as applied in the manufacture of rubber balls, it will be found especially
advantageous in the manufacture of irregularly shaped articles, such as dolls and
the like.
The seam in the finished and vulcanized ball has the edges upset or thickened on
the inside as shown clearly in Figure 7 and hence the chances of separating or.
tearing apart at this. point is reduced to the minimum.

page_text: The form of the seam leaves no rough or free edges on the inside of the ball as
in the lap joint constructions nor does it have the inherent weakness of the plain
-seam with abutted edges.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :
1. The herein described art of manufacturing hollow articles of elastic material
consisting of euperposing sheets of stock or material from which the article
is to be formed, confining the sheets together along the line they are to be
united separating the sheets in the confined area to set or form the stock and
finally uniting the sheets along the edge of the confined area; substantially as
.described.
2. The herein described art of forming hollow articles of elastic material
consisting in superposing sheets of material from which the article is to be formed
confining the sheets together along the line they are to be united, inflating the
confined area and finally while so inflated uniting the sheets along the edge of the
confined area; substantially as described.
3. The herein described art of manufacturing hollow articles of elastic material
consisting in forming the article ready for inflation, then inflating it and
-simultaneously supporting those portions subjected to the greatest tension, whereby
a uniform expansion or attenuation of the material is secured; substantially as
.described.
4. The herein described art of manufacturing hollow articles of elastic material
consisting in forming the article ready for inflation, then inflating it and simul-
taneously supporting with a yielding pressure those portions subjected to the greatest
tension, whereby a uniform expansion or attenuation of the material is secured;
substantially as described.
5. The herein described art of manufacturing hollow articles of elastic material
consisting in superposing sheets of the material from which the article is to be
formed, clamping the sheets together on a line approximating the shape of the
article and finally uniting the sheets autogeneously and severing the same from
the surrounding material by pressure applied within the clamped area whereby the
material displaced is forced inward to form a seam with thickened or upset edges
on the inner side; substantially as described.
6. The herein described art of manufacturing hollow articles of elastic material
consisting in superposing sheets of the material from which the article is to be
formed confining the sheets together along the line they are to be united, inflating
the confined area and simultaneously supporting those portions subjected to
greatest tension to secure a uniform attenuation, and finally severing the sheets
while inflated by pressure applied within the confined area whereby the material
-displaced is caused to flow inward and form upset or thickened seams; substantially
as described.
7. In a machine for making hollow articles of elastic material, the combination
with the co-operating concave dies having co-operating severing edges for
severing the material held between them and clamping dams surrounding the
edges of said dies and having co-operating clamping edges for clamping the
material, of inflating injectors movable toward and from the dies; substantially as
.described.
8. In a machine for making hollow articles of elastic material, the combination
with the co-operating concave dies, of the clamping dams surrounding said dies,
movable with relation thereto and normally standing in advance of the edges, of
the dies, whereby the clamps may remain stationary while the dies advance and
means for inflating the article held by the dams; substantially as described.
9. In a machine for making hollow articles of elastic material, the combination
with the concave die and co-operating die, of an anvil arranged centrally of the
concave die for supporting the portion of the material subjected to the greatest

page_text: tension with means for inflating the article neid by the dies; Substantianty
described.
D
10. In a machine for making hollow articles of elastic material the combination
with the co-operating concave dies, and means for inflating the article therein, of
independent anvils arranged centrally of the dies for supporting the portions of
the material subjected to the greatest tension while being inflated; substantially as.
described.
11. In a machine for making hollow articles of elastic material, the combination.
with the co-operating concave dies, of yielding anvils located centrally of each of
said dies for supporting the portion of the material subjected to the greatest.
tension and a means for inflating the article within the dies; substantially as.
described.
12. In a machine for making hollow articles of elastic material, the combination.
with the co-operating concave dies and the yielding clamps surrounding the dies,.
of the supporting anvils arranged centrally of the dies and a means for inflating
the article within the dies; substantially as described.
13. In a machine for making hollow articles of elastic material, the combination
with the co-operating concave dies and the yielding clamps surrounding the dies, of
the yielding supporting anvils centrally located in the dies and a means for inflating
the article within the dies.; substantially as described.
14. In a machine for making hollow articles of elastic material, the combination
with the co-operating concave dies of the movable anvils forming the bottom of the
dies and locks for said anvils; substantially as described.
15. In a machine for making hollow articles of elastic material the combination
with the co-operating concave dies, of the spring pressed anvils forming the
bottom of the dies and the locks for holding the anvils retracted; substantially as.
described.
16. In a machine for making hollow articles of elastic material, the combination
with the dies movable toward and from each other, of the injector for inflating the
article movable toward and from the dies; substantially as described.
17. In a machine for making hollow articles of elastic material, the combination
with the dies movable toward and from each other and the yielding clamps.
surrounding the dies, of the injector for inflating the article adapted to rest between
the faces of the clamps; substantially as described.
18. In a machine for making hollow articles of elastic material, the combination
with the co-operating dies and injector for inflating the article in the dies, of a.
valve for allowing the pressure from the article to escape whereby the pressure.
may be reduced; substantially as described.
19. In a machine for making hollow articles of elastic material, the combination.
with the co-operating dies and injector for inflating the article in the dies, of a.
pressure reducing valve connected with the injector, whereby the pressure in.
the article may be reduced before its release from the dies; substantially as
described.
20. In a machine for making hollow articles of elastic material, the combination.
with the co-operating dies, mechanism for moving said dies toward and from each
other and spring pressed anvils in the dies, of bolts for holding said anvils retracted
when the dies are together, with means whereby the bolts are released automatically
by the separation of the dies to permit the anvils to advance; substantially as.
described.
21. In a machine for making hollow articles of elastic material, the combination
with the dies movable toward and from each other and the spring pressed anvils.
within said dies, of the bolts for holding said anvils retracted and the inclines for
withdrawing said bolts as the dies separate to allow the anvils to advance ;
substantially as described.
22. In a machine for making hollow articles of elastic material, the combination
with the dies movable toward and from each other, of the injector, a manually

page_text: operated treadle controlling said injector and a stop for arresting the backward
movement of said injector at an intermediate point; substantially as described.
23. In a machine for making hollow articles, the combination with the driving
mechanism and dies movable toward and from each other, of the injector a spring
for retracting and a manually operated treadle for controlling the advance of the
injector, and stops released by the driving mechanism for holding the injector
advanced; substantially as described.
24. In a machine for making hollow articles from soft rubber, the combination
with the stationary dies having the clamps surrounding the same, of the movable
dies having the clamps surrounding them, the sliding head carrying the movable
dies, the crank shaft. for reciprocating the sliding head, the driving gear and the
intermittingly operating clutch between the driving gear and shaft; substantially
as described.
25. In a machine for making hollow articles from soft rubber, the combination
with the stationary and movable dies and the sliding head carrying the movable
dies, of the crank shaft for reciprocating the sliding head, the toothed disk thereon,
the driving gear the pawl thereon adapted to engage the toothed disk and the fixed
guide for throwing the pawl into engagement; substantially as described.
Dated this 17th day of December 1805
W. P. THOMPSON & Co.,
Agents for the Applicants.