IMPROVEMENTS IN MACHINES FOR BORING AND TAPPING PIPE FITTINGS
Year: 1884

page_text: I FREDERICK GRINNELL, of the City and County of Providence, State of Rhode
Island, United States of America, Gentleman, do hereby declare the nature of
my invention for "IMPROVEMENTS IN MACHINES FOR BORING AND TAPPING PIPE
FITTINGS" and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
My invention relates to machines for boring and tapping pipe fittings, such as
elbows in which two screw threads of the same or different size are cut at right
angles to cach other and T-pieces in which three outlets are tapped with screw
threads to receive three pipes of the same or different diameters, and also other
similar fittings having more than one outlet or screw-threaded opening into which
pipes are to be fitted.
My invention consists in the peculiar and novel construction of the machine by
which simplicity of construction, and greater accuracy in cutting the screw-threads
are attained, and my invention further. consists in the peculiar and novel
construction of the leading-screw, all as hereinafter set forth.
In the various fittings, used to connect steam, water, and other similar pipes, the
screw-threads must be cut with the greatest possible care and accuracy in order
that the screw-connection may be able not only to sustain the usual strains incident
to other screw-connections, such as are made in rods and other similar devices, but
these connections must be capable of sustaining strains from very high internal
pressure within the pipes and also from the varying strains due to expansion and
contraction, in order that the slightest leakage inay be avoided and that the
connections may remain tight for an indefinite length of time.
.
The tapping of two or more outlets in pipe-fittings requires the expenditure of
a great deal of power, particularly when such fittings are of large diameters, and
the sudden applications and cessations of power produce great strains not only
upon the machine but also upon the shafting and other connections by which the
power is transmitted from the motor to the machine. It is one of the objects of
this invention to avoid such strains upon the machine and its driving connections,
and to this purpose I construct the machine with two sets of mandrels, holders, and
gears so arranged that while the taps of one set are cutting the threads, those of the
other set are running back and two fittings are being operated upon simultaneously.

page_text: It is also necessary, in cutting threaded pipe-fittings, that the surface upon which
the thread is to be cut should be perfectly clean and that the rough skin of the
metal should be removed to allow the cutters to properly enter the metal; this
I accomplish by a peculiar and novel construction of the tap, as hereinafter set
forth.
Another object of my invention is to hold the fittings against the twisting action
of the taps, and this I accomplish by the peculiar and novel construction of the
holding-device and also of the machine-frame, as hereinafter described.
A further object of my invention is to so construct the machine that one operator
can conveniently attend to the tapping of two fittings, and also to double the
product or capacity of the machine by adding the gears for another set of taps;
whilst the strength of the required gears and shafts is not greater than would be
employed in a single machine. This I accomplish by constructing the machine
with two decks placed one above the other and both before the operator; the
arrangement being such that whilst the taps of one deck are cutting the threads
the taps of the other deck are being withdrawn.
In the accompanying drawings-
Figure 1 is a plan view of the machine, showing the three mandrels and their
supporting sleeves and the connections thereof with the central supporting-plato ;
the hand-wheel being removed.
Fig. 2 is a sectional view of the machine, showing the two sets of mandrels.
Fig. 3 is a side view of the machine, showing the mandrel-driving gears.
Fig. 4 is a front view of the machine.
Fig. 5 is a top view of the same, showing the hand-wheel for securing the pipe-
fittings.
Fig. 6 is an end view of the machine.
Fig. 7 is a side view of one of the larger taps.
Fig. 8 is an end elevation of the same.
Fig. 9 is a sectional view, partly in elevation, of the sleeve and the leading-screw,
the mandrel, and the driving-gear supported in the sleeve.
Fig. 10 is a side view of one of the smaller taps:
Fig. 11 is an end view of the same.
Fig. 12 is an end view of one of the larger taps.
Fig. 13 is a front view of one of the tap-rings.
In the said drawings A designates the upper and A¹ the lower table on which
the pipe fittings are supported. These tables are of such size as to accommodate
fittings of various sizes and are made very strong. The tables are provided with
the flanges a which are placed so as to fit securely against the planed faces of the
standards B to which they are firmly and rigidly bolted. The standards B, the
sleeves C, and the standards D form one frame and three of these frames are used
to support the machine; all of the three frames being firmly bolted to the three
sides of the tables A, A¹, so as to form a three-part support for all of the working
parts of the machine. By this arrangement the front part of the frame is left
open and unobstructed, so that one operator can easily attend to both sets of
tapping-devices. The tables A, A¹, are each provided with a raised rim to form
a receptacle for the oil, that is supplied in a continuous flow to the taps, and these
receptacles are connected by means of pipes with a well from which the oil, after
being strained, is again supplied by a pump. For the purpose of accurately and
quickly centering the pipe-fittings the tables A, A, are each provided with sockets
into which the bolsters a², to hold tho fittings, are placed so as to insure the exact
alignment, both vertically and horizontally of the sockets with the axes of the
three mandrels. The mandrels E, which carry the taps, are eack provided with
the screw-thread E' having the exact pitch of the threads on the taps, so that, on
turning the mandrel in either direction, the tap is fed to, or withdrawn from, its
work without faulty action. The screw E¹ is threaded in the nut E² which is
secured in the sleeve C and bears against the end of said sleeve which forms part
of the standard B; therefore the thrust of the arbór or mandrel is against the
+

page_text: face of the standard B and is as close to the pipe-fitting to be operated upon as
is compatible with the working of the machine. The standards B, B, are firmly
bolted to the tables A, A¹, and therefore the yielding of the machine to the thrust
of the arbor or mandrel, and the consequent stripping of the thread, when the
machine is reversed, are avoided. The mandrel E is provided with the spline e
which enters a groove in the hub f of the driving-gear F the bearing of which is
in the sleeve C and which is beld in place by the ring f¹ made in two parts or half-
sections, as is shown in figure 9. The mandrel E, being turned by the gear F, is
free to move laterally and is guided by the screw-thread E'. One of the mandrels E
and nuts E may be readily removed and replaced by another similar mandrel and
nut, or the screw-thread El may be formed on a sleeve which is to be secured to
the mandrel E, so that, in exchanging one screw-tap for another; the mandrel
proper would not have to be removed.
The machine is driven by an open belt which is placed on the pulley G, and by
n crossed belt which is placed on the pulley G¹; either one or the other of these
belts being on the loose pulley G2 when the machine is running. This arrange-
ment for reversing the machine may, however, be placed on a counter-shaft, or
arranged in any of the well known methods for driving in reverso directions
at will
Secured to the driving-shaft is the small gear-pinion g which meshes into the
gear g¹ for driving the machine at its normal rate of working-speed. A larger
gear-pinion g is also secured to the driving-shaft and meshes with the gear g³
when the machine is to be run at a speed higher than its normal speed. At one end
of the shaft which carries the gears g', g³, is mounted a gear-pinion g' which meshes
with the gear f¹, and the latter meshes in turn with the gear F, so that the six
mandrels are all driven simultaneously. The beveled gears g³, g³, are secured
movably upon the driving-shaft by means of splines and the front one of these
gears is put into engagement with the beveled gears go when right-hand threads
are to be cut. The beveled gears gº are mounted fixedly on a shaft which extends
transversely to the driving-shaft, and the shaft which carries the gears g also
carries at each end a gear-pinion which meshes into the corresponding gear F¹.
When left-hand threads are to be cut the rear beveled gear g³ is put into
engagement with the beveled gears go. By these changes in the gears 95, 9º, the
motion of the machine is reversed for cutting left and right hand threads. Any
of the usual arrangements may be employed for moving the gears gas above
described.
H, H, are the hand-wheels by which the screw for holding the fitting is operated,
and h', ', are slides which pass through slots in the standards B and rest on the
sleeves C, C, as is shown in figures 2, and 3. These slides are provided with stops
and act as anchors, when inserted between the screw and the bolsters h, and take
up all of the strain caused by the entrance of one tap before the others have
entered, or by unequal resistance in the tapping.
i designates a bar or pin which carries the larger tap I and said bar is arranged
to fit into a socket in the end of the mandrel E. The bar i is formed with a
tapered cylindrical enlargement which fits into a central tapering socket formed
through the cylindrical body of the tap I, and said body is secured from turning
upon the bari by a key or pin which is inserted between a depression on the
enlargement and a similar depression on the side of the socket. Upon the
circumference of the tap-body are formed a series of longitudinal grooves or
depressions placed parallel with each other and having slight lateral extensions or
undercuts at their bottoms. These grooves extend the full length of the tap-body
and are open at each end and form sockets for a series of chasers and cutters,
presently to be described. designates a ring which surrounds the bar i and rests
against the rear end of the tap-body to which the ring is secured by set-screws.
Thus the ring forms a firm backing for the cutters. The front face of the
backing-ring is formed with a series of radial grooves or depressions into which
the rear ends of the chasers and cutters, before mentioned, rest; thus bracing tho

page_text: chasers and cutters laterally. The ring is driven by the mandrel E and drives
the chasers and cutters, and this arrangement constitutes one of the peculiar and
advantageous features of the tap. In order to prevent the tap from turning on
the mandrel E the end of said mandrel is formed with a square shoulder c' which
enters a corresponding socket or depression 2 in the rear face of the ring .
The chasers and the cutters are cach formed with an elongated body of
greater depth at one end than at the other and also each with a lateral extension
on its under side to fit the extension in the corresponding socket in the tap-body.
The cutters are longer than the chasers, so as to extend somewhat in front of thie
latter for the purpose of boring the inner sides of the fitting in advance of the
chasers. The outer faces of the cutters are smoothand are also laterally inclined
so as to form a raised cutting-edge upon the advancing side of each cutter.
The small taps I', shown in figures 10 and 11, which do not require the degree
of security that the larger taps do, are each formed simply with a square shoulder
which fits into a square hole or socket in the end of the mandrel.
It will be seen that, by my improved construction, all of the strain is practically
borne by the tables A, A', and that but little strain is borne either by the frame
or by other parts of the machine. The alignment of the mandrels and tho strain
upon the latter and also the stability of the whole machine are secured by the two
tables. When the tables are sufficiently strong and the standards are properly
bolted to them, the machine will resist any strain, resulting from its required work,
without the least yielding.
It is obvious that various modifications may be made in details of construction
without departing from the essential spirit of my invention. Furthermore, by the
double-deck form of the machine, one set of taps is always cutting the threads
while the other set is being withdrawn, and, as the two fittings are one above the
other, one operator can easily attend to both sets of taps; thereby doubling the
amount of work which the operator can turn out in a given time. Moreover,
the vertical construction and the use of two tables require less room, while
producing greater stability than has heretofore been the case with machines of this
class.
Having thus particularly described and ascertained the nature of my invention,
and the manner in which the same is to be carried out, I declare that what I
claim is―
1st. In a tapping-machine, the combination with a table on which the fitting
is secured, of the mandrels E, E, having their thrust-bearings near the taps,
constructed to support the mandrels close to the work, as described.
2nd. In a tapping-machine, the combination with the sleeve in which the
mandrel is supported, of a thrust-bearing for the leading-screw placed at the end of
the sleeve near the work, as described.
3rd. The combination with the tables A, A'; of the standards B, B, and the
mandrels E, E, driven by suitable gearing constructed to form two sets of gearing
one above the other, as described.
4th. The combination with the mandrels E, E, and the gears F, F, of the beveled
gears g³, g³, secured to shafts provided with the pinions g', g, arranged to turn two
sets of taps in opposte directions, as described.
5th. The combination with the three frames B, D, provided with the sleeves C
constructed to support the mandrels E, E, and the gears F, F', of the tables A, A',
constructed to support the fittings to be tapped and to connect the frame, as
described.
6th. The combination with the bolsters a², and the holding-screw, of the slide h¹,
constructed to hold the fitting, as described.
7th. The combination with the sleeve C, the mandrel E provided with the screw-
thread E and the spline e, of the nut E² secured in the sleeve and bearing against
its face, and the gear F provided with the hub f extending into the sleeve C
constructed to turn the mandrol, as described.

page_text: Sth. The combination with the tap provided with the cutters and chasers, of the
ring provided with the radial grooves to receive the cutters and chasers and with
the recess fitting the end of the mandrel constructed to turn the tap through the
ring, as described.
בז
11
104
1000
HASELTINE, LAKE & Co.,
For the Applicant.