Note: Descriptions are shown in the official language in which they were submitted.
CA 02363050 2001-11-27
ORBITAL WELDING APPARATUS AND CLAMPING ASSEMBLY THEREFOR
This is a divisional application of Canadian Patent
Application Serial No. 2, 054, 558, filed on October 30, 1991, and
entitled "Orbital Welding Apparatus".
Backcrround of the Invention
The subject invention is directed toward the art of
welding and, more particularly, to an orbital welding apparatus
for circular products such as tubes or rods.
The invention is especially suited for incorporation in
apparatus for welding small diameter tubing in closely confined
spaces and will be described with reference thereto. It should
be appreciated, however, that the invention is capable of
broader application and could be used in many different welding
devices of widely varying sizes for many purposes.
Orbital arc welding equipment is often used to weld
tubing and piping for use in fluid handling and processing
systems. Currently, there is significant interest in welding
small diameter tubing, fittings, and control equipment such as
valves, filters, and the like to form small, compact control and
processing systems. Frequently, the various components must be
welded in confined and nearly inaccessible areas. In addition,
system designers are desirous of reducing, to the greatest
extent possible, the size of the processing and control systems
by reducing the distance between components. Much effort has
been expended in miniaturizing tube fittings and system
components; however, the space required by the welding apparatus
has been a significant limitation on further system size
reduction.
CA 02363050 2001-11-27
The subject invention provides a unique combination of
features which allows welds to be made in extremely confined spaces
and under conditions which have heretofore prevented use of orbital
welding equipment. The invention makes it possible to obtain the
maximum system size reduction benefits through the use of
miniaturized fittings and components.
Brief Description of the Invention
In accordance with one aspect of the invention there is
provided an orbital welding apparatus which comprises a first
housing defining a weld head assembly and including a circular
rotor disposed therein for rotation about a first axis. A welding
electrode is carried by the rotor and extends radially inward
toward the first axis. Suitable drive gears are carried in the
first housing for rotating the rotor about the first axis and a
first drive shaft is drivingly connected to the gears and extends
from the first housing in a direction perpendicular to the first
axis. A second housing separate from the first housing forms a
power transmission and has a second drive shaft extending
therefrom. A flexible drive shaft means connects the first drive
shaft and the second drive shaft to conduct rotary drive forces
from the first drive shaft to the second drive shaft while
permitting the relative orientations of the first and second
housings to be freely adjustable. A third separate and independent
housing carries an electric drive motor and forms a power drive
2
CA 02363050 2001-11-27
motor module with a rotary output shaft. Releasable connecting
means are provided for quickly connecting the third housing with
the second housing for permitting connection and disconnection of
the rotary output shaft of the motor module with the second drive
shaft so that the motor module can be manually connected and
disconnected from the transmission and weld head assemblies quickly
and easily.
The described arrangement permits the same motor module
or power unit to be quickly changed between weld heads intended for
welding tubing of different sizes. Moreover, because the weld head
is connected to the transmission housing through a flexible drive,
the motor module can have various desired orientations relative to
the weld head module and the weld head module can be placed in
extremely confined quarters without requiring that the motor module
be associated therewith in a particular orientation.
In accordance with a more limited aspect, there is a gas
line extending through the flexible drive shaft meats to the
housing to allow gas to be supplied to the weld head.
Additionally, a gas supply connection extends through the motor
module housing. A valued connecting arrangement joins the gas line
in the motor module with the gas line in the flexible drive shaft
whenever a motor module is connected thereto. Preferably, the
valued connecting arrangement opens automatically when the motor
module is connected to the flexible drive shaft.
In accordance with a further aspect of the invention,
there are electrical power cables also extending through the
3
CA 02363050 2001-11-27
flexible drive shaft. Suitable electrical connectors are provided
so that power connection takes place automatically when the motor
module is connected to the flexible drive shaft. Thus, when
changing orbital weld head modules, there is an automatic
connection of both the gas and the electric power necessary for the
operation of the weld head assembly.
The subject invention also provides an improved tube
clamping assembly for use with the weld head to told the
cylindrical tube ends in axially aligned abutting relationship
l0 while the welding is performed to join the tube ends. The clamp
assembly generally comprises a rectangular base with an opening
extending therethrough defining a path of movement for slidably
receiving the orbital weld head. A first pair of transversely
spaced clamp arms extend from the base on opposite sides of the
base opening. A second pair of transversely spaced clamp arms
extend from the base on opposite sides of the opening in alignment
with the first pair of clamp arms. The first and second pairs of
arms include cooperating clamp jaws for gripping on opposite sides
of the tube ends and maintaining them coaxially aligned with a
first axis. The second pair of arms are mounted for pivotal
movement about a second axis which extends parallel to the first
axis and is in a common plane therewith which is aligned with the
path of movement of the weld head into the opening in the base
member. Additionally, actuating means are provided for moving the
second pair of clamp arms between their open and closed positions.
Further, in the closed position, the clamp arms mate along a line
4
CA 02363050 2001-11-27
which includes the common plane.
The described arrangement of the arms opening in the
manner described allows the clamp assembly to be moved into
position around tubes confined in corners and closely adjacent
walls since the movement of the clamping of the arms takes up a
minimum amount of space and does not require any significant amount
of space in the area beyond the outermost extent of the arms. That
is, the clamp arms engage in the manner of a pair of pliers being
moved into position on the tubing. Access to the side of the
tubing opposite the weld head is not required. Further, the design
requires a minimum amount of space on the lateral sides of the
clamp assembly.
A further aspect of the invention contemplates that the
arms of the clamp assembly are moved between their open and closed
position through the use of a cam actuating assembly wherein the
assembly is located in an enclosed position between the arms and
the base plate in a concealed and confined manner and wherein the
operating portions of the actuating means are located at a position
spaced remotely from the outer end of the clamp assembly. Thus,
when used in confined spaces, the actuating means are readily
operable even though the clamp elements are enclosed and confined
by surrounding environmental structure.
In accordance with another aspect of the invention, the
operating portions of the clamp assembly actuating means are
arranged such that when the orbital weld head assembly is in
operating position in the clamp assembly, interengaging portions
5
CA 02363050 2001-11-27
t
prevent opening or operating of the clamp arms. Thus, tt~e clamp
arms cannot inadvertently open during a welding operation.
As is apparent from the foregoing, a primary object of
the invention is the provision of an orbital welding apparatus
which is capable of being used in extremely confined spaces and
which can weld extremely small fittings and produce miniaturized
piping and control systems.
A further object of the invention is the provision of an
orbital welding apparatus of the general type described wherein the
l0 various modules used to make up the system can be oriented at
selectively different arrangements relative to one another while
the unit is being fitted to the components being welded and while
the apparatus in use and actually making a weld.
A further object is the provision of a system of the type
described wherein the same power and control module can be used
with a variety of different weld head modules so that the system is
capable welding tubing of many different sizes while being operated
off a single power module.
A further object of the invention is the provision of a
system of the general type described wherein a flexible drive
connection conveys rotary power, electrical power, and weld
environment gas simultaneously and wherein connection and
disconnection of the power unit from the weld head assembly
automatically connects and disconnects not only the rotary power
but also the electrical power and weld environment gas.
6
CA 02363050 2001-11-27
7
Brief Description of the Drawings
The invention may take physical form in certain parts and
arrangement of parts, preferred and alternate embodiments of which
will be described in detail in the specification and illustrated in
the accompanying drawings which form a part hereof, and wi~erein:
FIGURE 1 is a pictorial view showing the overall
construction and arrangement of the orbital welding assembly of the
subject invention:
FIGURES 2 and 2A are exploded pictorial views of the
transmission and orbital weld head units, respectively, which
together make up module B of the assembly illustrated in FIGURE 1;
FIGURE 3 is an exploded pictorial view of the drive motor
module A of the assembly illustrated in FIGURE 1;
FIGURE 4 is an exploded pictorial view of the tube
clamping and holding module C of the assembly illustrated in FIGURE
1;
FIGURES 5 - 8 are partial side elevational views of the
tube clamping and holding module, somewhat diagrammatic, showing
the operation of the clamp arm actuating mechanism:
FIGURE 9 is a cross-sectional view taken on line 9-9 of
FIGURE 1 and showing the mounting and side loading arrangement for
the electrode holder: and,
FIGURES 10 and 10A are pictorial views (partially in
cross-section) illustrating the manner in which the motor module is
joined to the transmission module;
7
CA 02363050 2001-11-27
Detailed Description of the Preferred Embodiment
Referring more particularly to the drawings wherein the
showings are for the purposes of illustrating a preferred
embodiment of the invention only, and not for the purpose of
limiting same, FIGURE 1 shows the overall construction and
arrangement of an orbital welding assembly formed according to the
subject invention and comprising a motor and drive module.A which
is arranged releasably connected to a transmission and welding head
module H which is associated with a tube clamp and holding module
Merely by way.of explanation and general background, the
various modules are arranged to be quickly and rapidly assembled
and disassembled so that, for example; the -motor and drive module
A can be used with different transmission and weld head modules H.
For example, a single motor and drive module can be used with a
variety of different sizes of transmission and weld lead modules.
Additionally, and for further example, the tube clamp god bolding
assembly C is quickly and easily releasable from the transmission
and welding head assembly H such that it can be separately
connected to and positioned relative to the tubing to be joined and
a multiple number of such tube clamping and holding units or
modules can be used with a single transmission and weld head module
to allow welding to take place while additional tube ends are
clamped in alignment by additional clamping and holding modules in
preparation for welding operation.
More specifically, and as best shown in FIGURE 3, the
8
CA 02363050 2001-11-27
motor and drive module comprises a relatively elongated mousing
assembly l0 formed by a pair of clam shell type housing halves 12
and 14 (shown in FIGURE 1) and a traverse end plate 16. The
components 12, 14 and 16 are formed from any suitable material such
as a non-conductive thermoplastic or other non-conductive material
having adequate strength and wear characteristics. An elongated
small diameter electric motor i8 is supported within the housing by
having its output end suitably connected to the end plate 16. The
drive shaft 20 of motor 18 extends freely through a suitable
opening in the end plate 16 into a comparatively large diameter
counterbvred section 22. A drive connection element 24 is pinned
or otherwise positively connected to the drive shaft 20 and,has an,
enlarged diameter end portion 26 which carries axially extending
pins 28. The pins 28 are retained in portion 26 and provide a
rotary drive connection with the transmission and weld head module
in a manner subsequently to be described.
At the opposite end of the housing assembly l0 there is
provided a central inlet opening or passage 3o through which the
electrical power lines or cables 32 and 34 enter the motor drive
housing. Also entering through the opening 30 is a gas supply line
36 which supplies an inert gas to provide a suitable inert gas
atmosphere about the welding operation which takes place in the
weld head module. Many different types of gas are used to provide
the necessary inert atmosphere and such are well known in the art.
The gas line 36 is connected to the head or end plate 16
and a flow line 38 is provided through the head end for connection
9
CA 02363050 2001-11-27
with the transmission and weld head module. A check valve 39 is
provided in flow line or opening 38 as down in FIGURE 7Ø In the
preferred embodiment, the check valve 39 is a simple ball member
39a which is biased toward a seated, sealed position by a spring
39b. The ball member 39a is moved open against the bias of spring
39b when the motor and drive module A is joined to the transmission
and welding head module as will subsequently be described.
As also seen in Figure 10, the power cables 32 and 34
are provided at their ends with electrical socket connectors 40
that, as will become apparent, allow a simple plug-in connection
with the cooperating elements of the transmission and weld head
module in a manner which will subsequently be discussed. The
arrangement of the socket type connectors 4o is conventional and
they are suitably retained in the end plate 16 while being
insulated therefrom.
At the entrance end to the housing assembly l0, the
cables 32, 34 and the gas line 36 are suitably enclosed by a
resilient protective hose member 37 which has its end clamped
between the housing half sections 12 and 14 (as shown in FIGURE 1).
Additionally, it should be noted that the housing sections are
releasably clamped together in any convenient manner such as
through the use of a plurality of socket head machine screws 42 or
the like.
Referring again to FIGURE l, it will be noted that the
motor and drive module A is connected with the transmission and
welding head module H through the use of a conventional over center
l0
CA 02363050 2001-11-27
type, lever actuated toggle or latch mechanism indicated generally
with the reference numeral 46. The use of such latch mechanisms is
well known and many different types of quick release connections
could equally well be used to allow positive connection of these
components while permitting ready disconnection when it i.s desired
to change the particular weld head assembly being used with the
motor and drive assembly or module A.
The Transmission and Weld Head Module Assembly H
Referring in particular to FIGURES 2 and 2A, the overall
construction and arrangement of the components which make up the
transmission and weld head module are shown in some detail in
exploded pictorial form. In general, the module H comprises a
transmission unit 50 and an orbital weld head unit 52. In the
subject embodiment and in the preferred form of the invention, the
transmission unit 50 and the weld head unit 52 are drivingly
interconnected by a flexible drive shaft assembly 54. However, in
certain environments and under certain conditions of operation, the
flexible drive shaft assembly 54 could be dispensed with and a
direct connection provided between the noted components. In
FIGURES 2 and 2A, the flexible drive shaft assembly 54 is shown as
of indeterminate length with opposite ends thereof shown connected
to each of the components 50, 52.
Referring more particularly to FIGURE 2, it will be seen
that the transmission unit 50 includes a three-part housing
11
CA 02363050 2001-11-27
including side elements or housing components 56 and 58 (see FIGURE
1) , which are basically mirror images of one another. The side
elements 56 and 58 cooperate to form a clam shell type housing
which is interconnected in a releasable manner to the end plate
member or wall 64 through the use of a suitable mechanical fastener
such as socket head machine screws 60. The outer configuration of
the housing as formed by the components 56, 58 has an overall size
and external shape which generally corresponds to the shape of the
motor module unit. More particularly, it should be noted that when
l0 assembled as shown in FIGURE 1, the outer end of the motor module
end plate 16 is closely received in the open end 62 of the.housing
of a transmission unit 50. This provides a close coupling and
sealing and encloses the electrical connections as well as the
drive elements.
Positioned within housing components 56, S8 and located
inwardly from the open outer end 62 is the rigid end plate member
69 which is also releasably connected to the housing components 56,
58 in any convenient manner such as through the use of machine
screws or the like (not shown). A counterbored section or opening
66 is formed in the end plate member 64 at the location shown. (See
Figure 10 also). Carried within this counterbored section 66 and
freely rotatable in suitable bearings located internally of the
opening 66 is a gear-like drive element or member 68. The external
periphery of the larger diameter end of the drive element 68 is
provided with a multiplicity of uniformly spaced, generally semi-
cylindrical recesses 70 which are sized and spaced so as to closely
12
CA 02363050 2001-11-27
and drivingly engage the axially extending pins 28 on the drive
connection element 24 (see FIGURE 3) when the units ire in the
coupled condition shown in FIGURE 1.
It should be noted that the opposite end of the housing
component 56, as well as housing component 58, include integral
wall sections formed to provide an outer end wall. The two dousing
components 56, 58 have mating semi-cylindrical recesses which
together define a cylindrical opening 72 which is sized to closely
receive the end 74 of the flexible drive shaft assembly 54. End 74
is a rigid metal collar and is clamped between the housing
components 56, 58 and held.therein through cooperating grooves as
illustrated.
The flexible drive shaft assembly 54 is .a conventional
flexible drive assembly. The-outer housing or sheath 55 of this
flexible drive assembly is formed of a braided Teflon hose covered
with a stainless steel braided outer layer. Extending axially
through the center. of the outer hou sing or sheath 55 is the
flexible drive shaft element 76 which terminates in a rigid drive
connection or end 78. The space available within the outer housing
or sheath 55 is sized so as to be capable of holding the electrical
cables 32a and 34a. Additionally, there is sufficient spice
through the interior of the housing so as to allow free passage of
the gas line 36 connecting with opening 38 (as shown in FIGURE 3).
In this regard, a suitable opening 8o is formed through tine end
wall 64 at a location corresponding to opening 38 in the end wall
16 of the motor and drive module A. A suitable sealed connection
13
CA 02363050 2001-11-27
is provided between openings 80, 38 by an O-ring 8i wt~ict~ is
located in a recess about opening 80 and engaged by boss 38a which
extends out about opening 38 as shown in Figures 10 and 10A. It
should also be seen that the ends of cables 32A and 34A are
connected to suitable plug type electrical connectors 82 and 84
respectively. These connectors are of conventional design and are
suitably mounted in the end wall 64 at locations corresponding to
the locations of the socket connectors 40 of the motor module A.
The end 78 of the flexible drive shaft element 76 is
connected to the drive member 68 by a cooperating flat and a C-ring
or spring clip. The C-ring 86 and the flat 78A provide a rotary
drive connection in which the shaft end 78 can axially move by
sliding as is required when the flexible drive unit undergoes
substantial bending. As can be appreciated, the overall
arrangement thus far described allows rapid connection and
disconnection of the motor module from the transmission unit 50.
Additionally, as can be seen, the electrical and gas connections
are made automatically upon a simple plugging together of the two
components.
The orbital weld head is, as previously mentioned,
connected to the opposite end of the flexible drive shaft assembly
54. The details of construction of the weld head are best
illustrated in FIGURE 2A. As shown therein the orbital weld head
52 generally comprises an outer frame and housing 90 which is
defined by a pair of opposed body sections or members 92 and 94.
These sections are suitably molded or machined from a non-
14
CA 02363050 2001-11-27
conductive, high strength, high temperature resistant material.
The body sections 92, 94 are joined in mating relationship in any
suitable manner such as through the use of socket head machine
screws 96. It should be seen that the body sections 92, 94 each
include a first generally rectangular end portion or body section
92A and 94A respectively. These sections cooperate to define an
internal chamber of generally rectangular shape into which a right
angle drive assembly 96 is releasably received. 'fhe details and
arrangement of the drive assembly 96 will subsequently be
described. For the present, however, it should be noted that the
body members 92 and 94 each further include relatively thinner and
smaller generally rectangular sections or members 92H and 94H
respectively. These sections are arranged to house the gearing and
transmission elements for connecting rotary motion from the right
angle drive assembly 96 to the rotor or electrode holder 98. In
this regard, FIGURE 9 together with FIGURE 2A shows .the overall
arrangement for the electrode holder and the mounting thereof.
More particularly, each of the sections 92H and 94B cooperate to
define a tube receiving through opening 100 and a laterally open
entrance area 102. This arrangement allows the tube ends to be
positioned in abutment and the weld head moved laterally thereover
to bring the abutted tube ends into alignment with the electrode
holder at the location necessary for performing the weld. The tube
ends are suitably held in proper alignment and position by the tube
holding and clamping assembly C in a manner subsequently to be
described. As shown, the rotor or electrode holder 98 is
CA 02363050 2001-11-27
-r
generally circular in shape but has an open side or opening 104
which is of a width sufficient to allow the holder to pass over the
exterior diameter of the particular size of tubing which the weld
head 52 is intended to weld. Both sides of the rotor or electrode
holder 98 have a continuous convex configuration as illustrated to
define a circular guide surfaces 106, 1o8. In the embodiment under
consideration, the electrode holder 98 is formed from a relatively
hard copper; however, any suitable wear resistant and electrically
conductive material could be used. The body section 92B is
provided with an inwardly extending machined groove 110 which is
concentric with the opening l00 and provides a guide track which
receives the guide surface 106. In the body section 94H, there is
a circular recess 112 which is coaxial with the opening loo and is
machined to receive a circular brush member 114. The brush member
114 has a circular shape with its upper surface shaped to form a
complementary guide track for the guide surface 108 on the rotor or
electrode holder 98. The surface is identified with the numeral
1i6 and extends circumferentially about the opening loo. The brush
member 114 is connected through an electrical bus bar 118 with a
connector 120 which is joined to the end of the power cable 34A
(shown in FIGURE 2). The power cable 32A (shown in FIGURE 2) is
electrically connected with a plug element 122 which extends
outwardly adjacent the sections 92B and 9.4H as illustrated in
FIGURE 2A. This completes an electrical circuit from cable 32A to
the tube holding and clamping module C in a manner subsequently to
be described.
16
CA 02363050 2001-11-27
The electrode holder 9s carries a suitable tungsten
electrode 126 which is adjustably clamped i.n the bolder by ~ set
screw 128. As can be appreciated, rotation of the electrode holder
about the axis of opening loo allows a weld to be performed on
abutting tube ends suitably positioned within the opening loo in a
manner well known in the art.
The rotation of the electrode holder 98 is accomplished
through a gear train connected with the right angle drive assembly
96. In this regard, it should be noted that the outer periphery of
the electrode holder 98 is provided with gear teeth 130 which mate
with corresponding teeth carried. on the individual mating gears 132
and 134. Gears 132 and 134 are positioned as shown and carried on
suitable axles and bearings mounted. in the section. 94B as
illustrated. Drive gear 136 is in driving engagement with the
gears 132 and 134 to provide two separate drive trains from the
right angle drive unit 96. This allows drive to be maintained even
though the electrode holder 98 includes the opening 104. That is,
the gears 132 and 134 are spaced apart a distance greater than the
opening 104 so that one or the other of the gears is always in
contact with the geared periphery of the electrode holder 98 at all
times. The drive gear 136 is, of course, in driving engagement
with the output gear 140 of the right angle drive assembly 96.
It should be noted that the right angle drive assembly 96
includes a machined block frame or housing element 142 which is
preferably formed from a high strength thermoplastic and sized to
be closely received and located by the recesses formed within the
17
CA 02363050 2001-11-27
body sections 92A and 94A in the manner illustrated. The output
gear 140 is suitably carr ied a bearing and pin assembly which
on
extends bottom of the housing or frame element
upwardly
from
the
142. A bevel gear element 144 formed integrally with the output
is
gear 140 and mates with a corresponding
bevel
gear
146
mounted
horizontally in a pair of bearings 148. The bearings 148 are
suitably received in an opening 151 formed at the right hind end of
block 142. The drive lug from the flexible drive element 76 is
received in the interior of the shaft joined to the bevel gear 146
and is connected therewith through the use of a C-ring 152. This
connection is also arranged to allow axial movement of the shaft
portion 150 relative to the bevel gear 146 to permit axial movement
as required during bending of the flexible drive cable 54. This
connection is merely flats formed on the sides of shaft portion 150
which slidably engage the C-ring 152. By forming the right angle
drive unit as a separate component with its own frame, maintenance,
repair, and replacement of the drive is simplified.
The exterior housing of the flexible drive cable. assembly
54 is connected at its end through a metal sleeve or end portion
156 that is clamped between the body sections 92A and 94A and
joined thereto through a socket head maclnine screw 158.
In addition, connecting means 153 is provided to provide
section 92a. Connecting means 153 is hinged to body section 92a
with pin means 155.
The Tube Clam~inq and Holdinq_Module C
18
CA 02363050 2001-11-27
The module C can best be understood by reference to
FIGURE 4 which shows the module in somewhat of an exploded
pictorial view. Broadly, the tube clamping and holding module is
designed so as to be of minimum size capable of performing the
function to thereby allow it to be used in extremely tight cramped
spaced and to assembly miniature tube fittings in extremely compact
small assemblies. The module is preferably formed from a high
strength metal such as stainless steel and generally comprises a
l0 first substantially rectangular base assembly 16o comprising a pair
of side members 162 which are joined by end members 164. The base
defines a rectangular opening 166 which is sized to closely but
slidably.receive members 92B and 94B of the weld head assembly 90.
FIGURE 1 shows the weld head 90 and the fixture block module C in
the assembled condition: When in this assembled condition, the
members 92H and 94H extend through the base assembly 160. such that
the opening 100 is located outwardly thereof or to the left as
viewed in FIGURE 4. Additionally, it should be understood that the
base includes a boss with an opening yr socket to receive plug.
element 122 (see FIGURE 2A) to assure a good electrical connection
with electrical cable 32a.
Associated with the base element 160 are a pair of
outwardly extending clamp arms 168 which are joined to the base or
formed integrally therewith to extend perpendicularly outward on
opposite sides of the opening 1s6 to closely enclose the members
92H and 94H of the weld head assembly 90. In the embodiment under
19
CA 02363050 2002-11-13
consideration, the pair of arms 168 are rigidly positioned and
interconnected by a cross piece 170. Associated with the first
pair of arms 168 is a second pair of clamp arms 172 which extend
outwardly from the base assembly 160 in opposed aligned
relationship with the first pair of arms 168. As will
subsequently be described, each of the arms 172 are mounted for
independent pivotal movement relative to the arms 168. The
actual mounting and actuating mechanism will subsequently be
described. However, it should be noted that each arm of the
first pair of arms, as well as each arm of the second pair of
arms, carries a tube clamp jaw 174. Although they could vary in
construction, each of the claim jaws 174 are identical and are
of generally semi-circular shape and define a semi-cylindrical
clamp face 176. The individual jaws 174 are provided with
internal machined cuts 178 to produce resilient clamp portions
such that the clamp faces themselves can resiliently engage the
periphery of the tube ends being clamped. This design are
resilient nature of the clamp faces is the subject of a prior
U.S. Patent No. 4,868,367 and commonly assigned U.S. Patent No.
4,973,823 issued on November 27, 1990 for "Collet Assembly for
Cylindrical Workpieces". Each of the individual clamp jaws is
provided on its outer surface with a flange 180 which is engaged
with a corresponding counterbore 182 formed in the circular
recess into which it is respectively received in the
corresponding arm element. Preferably, the individual clamp
jaws are welded or otherwise positively connected in position in
their respective clamp arms.
CA 02363050 2001-11-27
It should be noted that each of the jaws is located such that when
the movable second set of clamp arms 172 is actuated to the closed
position illustrated in FIGURE 1, the clamp jaws define spaced
apart tube holding cylindrical sections which are located closely
adjacent and coaxial with the electrode holder 98 of the weld head
assembly 90. Additionally, it is preferable that the individual
arms of the first and second sets of arms be provided with means to
assure proper mating and alignment when they are in the tube
clamping or closed position illustrated. For ttnis purpose, the
arms 172 are provided along their mating edge with a tongue element
18~ which is arranged to be received within a corresponding groove
186 formed along the mating edge of the first pair of arms 168.
Thus, when the arms are in the closed or tube clamping position,
these cooperating tongues and grooves assure proper alignment of
the individual arms relative to the orbital weld head 90.
Of particular importance to the tube clamping and holding
module C is the manner in which the movable arms 172 are mounted
and actuated. As illustrated in FIGURE 4, each of the.arms 172 are
independently mounted for rotation about an axis 188 which extends
transversely through the opening 166 and generally perpendicular to
the path of insert movement of the weld head into the module C.
This path of movement is illustrated generally by the arrow 190.
Additionally, the two arms mate along a plane which includes the
axis of opening 100 of the weld head module 90 as well as the axis
188. It has been found that when the jaws can be opened in this
manner, the weld head and tube clamp assembly are capable of being
21
CA 02363050 2001-11-27
inserted into extremely confined areas and can make welds on tubes
located in structural corners and other confined areas not
otherwise weldable with typical prior art units.
Although the particular manner of mounting the movable
arms 172 could vary, in the subject embodiment a pair of shoulder
screws 192 are received through suitable openings formed in the
arms 172 and threadedly engaged with the sides 162 of the base
assembly 160. Each of the arms 172 are independently actuated by
a separate actuating means which takes the form in the subject
embodiment of separate cam actuating assembly 194 and 19411. These
cam actuating assemblies are independently operable a.nd move the
associated arm 172 independently between open and closed positions.
They are, however, mirror images of one another as can be readily
appreciated. For present purposes, a detailed description of the
assembly 194 and its method of operation should be understood as
equally applicable to assembly 194A subject to the understanding
that 194A is a mirror image of 194. Referring in particular to
FIGURES 4 - 8, the operation of the operating or actuating assembly
194 can be understood. Specifically, as shown, the actuating
assembly 194 includes a cam plate member 196 which is mounted for
pivotal movement about a pin 198 which is positioned such that the
axis of rotation of the cam plate member 196 is parallel to the
axis 188. The cam plate is located in an enclosed position between
the lateral side 162 and the associated arm 172 as best seen in
FIGURE 4. Each of the arms 172 includes a cam surface 20o which is
inclined as best shown in FIGURE 5. The cam surface 20o extends
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CA 02363050 2001-11-27
transversely of the arm and is engaged by an outwardly extending
cam lobe 202 carried on plate member 196. ndditi.omlly, tl~e
overall shape of plate member 196 is best illustrated in FIGURE 5
and includes a laterally extending handle portion or actuating
member 204 which is accessible from ttte end of the module C. The
cam plate 196 also carries a pin 205 wlo.ch extends outw~r.dly
through the arm 172. As best illustrated in FIGURES 4 and 5, the
arm includes a somewhat L-shaped opening 206 into which the pin 205
and the outer end of pivot pin 198 can extend.
Referring more particularly to FIGURES 5 - 8, the overall
operation of the actuating mechanism can best be understood.
FIGURE 5 shows the arm 172 in its tube clamping or closed position.
In this position, the cam lobe 202 is in somewhat of an over center
position and the pin 205 is spaced from the sides of the L-shaped
opening 206. If the actuating member 204 is pulled in the
direction of the arrow shown in FIGURE G, the pin 205 engages the
side of opening 206 as shown. With further movement in the
direction of the arrow, the cam plate is rotated rotating the pin
205 to engage the surface and drive the arm 172 in a counter-
clockwise direction. Continued movement moves the arm to a full
open non-clamping position as illustrated in FIGURE 8. In this
position, the spacing between the outer ends of the arms 172 and
the cooperating arms 168 are such as to allow the jaws to be moved
into and out of engagement with the tube ends which are being
welded or have just been welded. '
When the cam plate member is actuated in the opposite
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CA 02363050 2001-11-27
direction, the cam lobe 202 engages with tl~e surface 20o and
applies a closing force to move the associated arm 172 beck in a
clockwise direction to a closed direction as viewed in F.LGURFS 5 -
8. It should be noted that throughout this movement that a
positive drive takes place and when in the FIGURE 5 position, the
cam plate 196 i's generally in a slightly over center position so
that it tends to maintain its clamped position until it is manually
moved in the opening direction. It should be noted further that
during the closing operation, the pin 205 does not act to move the
arm 172.
The invention has been described with reference to the
preferred embodiment. Obviously, modifications and alterations
will occur to others upon a reading and understanding of this
specification. It is intended to include all such modifications
and alterations insofar as they come within the scope of the
appended claims or the equivalents thereof.
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