IMPROVEMENTS. IN TUBE EXPANDERS
Year: 1888

page_text: I, CHARLES. HENRY ROBINSON, of the City of St. Paul, in the County of Ramsey,
and State of Minnesota, in the United States of America, Machinist do hereby declare
the nature of my said Invention for "IMPROVEMENTS. IN TUBE EXPANDERS" and in
what manner the same is to be performed to be particularly described and ascertained
in and by the following statement reference being had to the accompanying sheet of
drawings and to the letters and figures marked thereon :-
:
The present invention relates to tube expanders used for expanding the tubes of
boilers and the like, to make them fit tightly in the flue sheets or heads of the boilor.
The expander in its general construction comprises a metallic head cast of a single
piece of metal with a series of equi-distant radial channels, which all open into an
interior central longitudinal bore. In each of these radial channels is located an
expanding roller which is greater in diameter than the thickness of the head between
its central bore and its outer surface, so that the rollers may project within the central
bore and also at the same time beyond the outer surface of the head. The expander
is operated by means of a tapering mandrel which enters the central bore and forcés
out the expanding rollers. As the mandrel is forced inward it is rotated thus
turning the expander head and bringing the rollers in contact with the entire inner
periphery of the tube in which the expander is inserted. The expander and its novel
features are illustrated in the accompanying drawings, in which
Fig. 1, is a side view of the expander complete, a portion of the tapering expanding
mandrel being shown in position therein. Fig. 2, is a central vertical longitudinal
section of the expander. Fig. 3, is a cross section in a plane indicated by the
line 3-3 in Fig. 1. Fig. 4, is a cross section in a plane indicated by the line 4-4
in Fig. 2, showing the mandrel also in section. Fig. 5, is a perspective view of the
expander head with the expanding rollers and its supporting collar removed: Fig. 6,
is a perspective of one of the expanding rollers in detail...
.
A, represents the main body or head portion of the expander having its lower
portion B, reduced and encircled by a collar C, the latter fitting loosely upon and
adapted to be rotated freely around the reduced portion B, but prevented from being
moved longitudinally thereon by a set screw a, fitting into a circumferential groove b,

page_text: I
in the reduced portion B. The collar C, is provided with lugs c, c, projecting from
opposite sides of its periphery to form stops to rest against the flue sheets or boiler
head and support the expander in its proper place in the tube during the process of
expanding the same.
The head A, with its reduced portion B, is formed preferably by casting in a single
solid piece having a central longitudinal bore D, and channels E, E, extending radially
and laterally, through the head, and communicating with said central bore. Into
each of these channels is inserted an expanding roller F, each roller being greater
in diameter than the thickness of the metal of the head between its exterior surface
and the central bore, so that when arranged as shown in Fig. 4, the rollers will project
into the central bore and also beyond the exterior surface of the head. The upper
end of each expanding roller is formed with a circular recess of cavity d, and into
this cavity or recess the lower end of a stop pin e, enters, the. latter being preferably
a screw which tapped down through the top of the head with its lower point projecting
into one of the.radial.channels E. The stop pins.thus.prevent the rollers, from falling
out of the radial channels when the implement is not in use.
In Fig. 2, one of the expanding rollers is shown in section with the lower point of
its stop pin projecting down into the cavity or recess d. The roller in this figure is
shown in its outermost position:
In Fig. 3, one of the expanding rollers is shown in its outermost position, one at
its innermost position, and the remaining roller at an intermediate position, to
illustrate the extent to which the rollers are free to move. The extent of movement
it will be noted is determined by the diameter of the recesses or cavities in the ends
of the rollers.
In using this implement the expander head is inserted into the tube to be expanded
with the lugs c, c, resting against the flue sheet or boiler head. A tapered mandrel G
is then driven in from the outside through the central bore of the head. The head is
'smaller in diameter than the interior diameter of the tube to be expanded so that only
the expanding rollers come in contact with the interior surface of the tube, and the
mandrel being smaller in diameter than the central bore, acts only on the rollers and
forces them outwardly against the interior surface of the tube. The mandrel is then
rotated in the head carrying with it the head which turns in the collar C, and also
the expanding rollers which are thus brought in contact with all portions of the
interior surface of the tube and press it very tightly against the edge of the flue
sheet or boiler head, thus forming a steam tight joint between the tube and flue sheet
or boiler head.
Three of the expanding rollers are shown in the head which is the number usually
and preferably employed, but a greater number may be employed if desirable.
By forming the head in a single piece of metal the implement is produced at the
minimum cost, while at the same time it is stronger and more durable than if made
in two or more parts connected by screws or rivets.
A great advantage is also attained by the means employed for preventing the
expander rollers from falling out of the radial channels consisting in the largo circular
cavities or recesses in the upper ends of the rollers into which the lower points of the
stop pins project.
These stop pins are never subjected to a greater strain than the weight of the rollers,
and that only when the implement is not in use or is being carried about. The rollers
can never come in contact with the stop pins when the implement is in use, as will be
readily understood from the construction shown, the strains being all borne by the
solid metal of the head.
✓ Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner. the same is to be performed I declare that what I
*claim is :
1. In a tube expander a head having a central longitudinal bore and channels
extending radially and laterally through said head, and communicating with said

page_text: each of said rollers having on one end a cavity or recess, and stop pins inserted through
the head of the tube expander with their ends entering the recesses in said rollers,
substantially as set forth.
2. In a tube expander, a head cast or formed in a single piece having a central
longitudinal bore, and channels extending radially and laterally through said head
and communicating with said central bore, in combination with expanding rollers
located in said radial channels each of said rollers having on one end a cavity or
recess, and stop pins inserted through the head of the tube expander with their onds
entering the recesses in said rollers substantially as set forth.
3. In a tube expander, a head having a central longitudinal bore and channels
extending radially and laterally through said head and communicating with said
central bore in combination with expanding rollers located in said radial channels,
each of said rollers having on one end a cavity or recess and having its opposite
end plain and square, and stop pins inserted through the head of the tube expander
with their ends entering the recesses in said rollers, substantially as set forth.
4. As a new article of manufacture, an expanding roller for a tube expander, said
roller having one end plain and square, and having a cavity or recess in the opposite
end, substantially as and for the purpose set forth.