Note: Descriptions are shown in the official language in which they were submitted.
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QUICK CH~NGE TOOLING METHOD l~ND APPA~$US
Backqround and Field of Invention
This invention relates to tube hen~; ng
apparatus, and more particularly relates to a novel
and improved method and apparatus for ~uickly and
accurately changing die sets for different-sized
tubing to be bent or for different types of tube
h~nr~; ng operations.
Tube bending operations require precise
alignment between a bend die, pressure die and
clamping die for each si~e of tube to be bent. In
many cases, a wiper die is required along with a
mandrel which is inserted into the tube portion to be
bent. In the standard bending operation, holders are
provided on the bend die table which are movable into
engagement with the bend and clamping dies, and the
pressure die is advanced linearly as the bend die is
rotated with the tube to be bent being securely
clamped in complementary grooves therebetween to
undergo bending and assume the configuration of the
grooves as pressure is applied. In many tube bending
operations, a mandrel must be inserted into the tube
to be bent in order to prevent wrinkling or collapse
of the portion of the tube being bent; and in many
cases, a wiper die is employed in cooperation with the
pressure die to regulate the pressure applied to the
tubing during the bending operation.
In changing the various dies for different-
sized tubing, the st~n~rd practice has been toindividually remove the dies and reassemble a new die
set onto the table which is time-consuming and results
in considerable downtime. In certain tube bending
.
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applications, it has been proposed to be able to
remove more than one component part of the die set in
one step or to provide special devices to facilitate
replacement of the die set in an effort to reduce
downtime and, for example, reference is made to U.S.
Letters Patent Nos. 4,178,788 to R. T. Zollweg et al,
4,355,525 to J. W. Carson, 4,967,585 to S. Grimaldo,
5,148,695 to H. S. Ellis, 5,339,670 to A. Granelli,
5,426,965 to W. G. Hopf and 5,499,521 to M. E. Luikart
et al. Nevertheless, to the best of our knowledge, no
one has devised a one-step operation in which
component dies of the tube bending apparatus can be
removed from the bending table and stored in assembled
form so as to retain the same precise alignment and
relationship established from the previous bending
operation. In this way, the apparatus can be
remounted on the table as one unit and remain in the
desired relationship so as not to require extensive
set-up time in preparing for the next bending
operation for that particular sized tubing; and
further wherein the die set or kit is so assembled and
arranged as to facilitate automated removal and
reinstallation with respect to a standard die table as
well as the ability to rapidly and accurately locate
one or more die sets at one time with respect to the
bend die table.
SummarY of the Invention
It is therefore an object of the present
invention to provide for a novel and improved quick-
change tooling method and apparatus for tube bendingoperations.
It is another object of the present
invention to provide for a novel and improved means to
preassemble die sets employed in tube bending
operations into a unitary assembly which can be
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removed from and replaced on a tube bending table in
a one-step operation thereby ~ubstantially reducing
downtime between tube bending operations.
- It is a further object of the present
invention to provide for a novel and improved method
of preassembling tube bending dies into a unitary
assembly for one-step removal and replacement of die
sets into accurate alignment with the bender machine
for different sized tubing and different types of tube
bending operations.
It is a still further object of the present
invention to provide for a method of bending different
sized tubing wherein die sets for each sized tubing
are preassembled and can be automatically removed and
replaced with another die set without re~uiring
readjustment or realignment of the dies in each set.
In accordance with the present invention, a
preassembled die set has been devised for tube bending
apparatus wherein the die set is comprised of a bend
die, clamp die and pressure die adapted to be mounted
on a spindle of a tube bending table, the improvement
comprising first means releasably interconnecting the
pressure die and clamp die to the bend die in
predetermined, aligned relation to one another and to
the bend die, and handling means for engaging the die
set in order to simultaneously lift and remove said
dies comprising each die set from the table.
Preferably, the handling means is defined by lift
means operative to lift each die set from the table
and replace with another die set by lowering the other
die set onto the table and locating it in prealigned
relation to the table. Furthermore, each preassembled
die set preferably includes a straight or bent tube
corresponding to the size of tube to be bent that
re~;nc in the die set in order to permit the
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connecting means to maintain the dies of each set in
aligned relation to one another. Many tube bending
operations require the use of a wiper die and mandrel
and which elements may also comprise a part of each
presassembled die set when needed.
The method of changing die sets in
accordance with the present invention comprises the
steps of interconnecting each of the die sets in
prealigned relation to one another for bending a
selected size of tube, mounting a selected one of the
die sets on a spindle support of a tube bending
machine with the pressure die and clamp die aligned
with one another and with the bend die, positioning
clamp and pressure die holders into engagement with
~S the one die set and releasing the connectors from
engagement with the one die set, bending one or more
tubes of a selected size by inserting into facing tube
grooves between the clamp die, pressure die and bend
die and rotating the bend die to bend the tube so
inserted, and releasing the clamp and pressure die
holders and connecting the connectors to releasably
interconnect the dies of the one die set followed by
lifting the one die set and removing from the spindle
support. Preferably, a tube corresponding to the size
of tube to be bent is left in the one die set prior to
removal so that the dies maintain their prealigned
relation when stored and later replaced on the spindle
for another tube bending operation of that size tube.
The above and other objects of the present
invention will become more readily appreciated and
understood from a consideration of the following
detailed description of preferred and modified forms
of the present invention when taken together with the
accompanying drawings in which:
~rief DescriPtion of the Drawinqs
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Figure 1 is a perspective view illustrating
- a conventional form of tube bending machine including
a die set consisting of a bend die, clamp die,
pressure die and wiper die in assembled relation to
5the machine with a mandrel inside of a tube to be
bent;
Figure 2 is a top plan view of a pre~erred
form of preassembled die set including a tube to be
bent;
10Figure 3 is a longitudinal sectional view of
a preferred form of mandrel disconnect for a mandrel
inserted into each tube to be bent;
Figure 4 is a top plan view of a lift
~ch~nism for removal and replacement of a
15preassembled die set in accordance with the present
invention);
Figure 5 is a side view in elevation of the
preferred form of lift ?~h~nism shown in Figure 4;
Figure 6 is a top plan view of a modified
20form of preassembled die set in accordance with the
present invention;
Figure 7 is a cross-sectional view of the
die set shown in Figure 6; and
Figure 8 is a cross-sectional view in more
25detail of the mounting of the wiper die arm on the
spindle.
Detailed Description of Preferred Embodiment
There is shown in Figure 1 a conventional
tube bending machine 10 having a main upper bed or
30table surface 12 upon which is mounted a mandrel
retract cylinder 14 having a plunger 16 affixed to an
end of z mandrel rod 18 for insertion of a mandrel,
not shown, into a tube T. A spindle 20 projects
upwardly from a swing arm 21 in order to control
35rotational movement of the swing arm 21 around
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overhanging portion 24 of the machine. Although not
shown, typically the machine 10 includes a degree of
bend adjustment which is regulated by an electronic
control panel, in accordance with the degree of bend
desired. An associated clamping die holder 26 which
is slidable on a way 28. Additionally, a pressure die
holder 30 is slidable on way 32, the clamp die holder
26 and pressure die holder 30 being movable into and
away from the dies to be described in a well-known
manner. One suitable form of tube bending machine is
the TBH-40, manufactured and sold by Tools For
Bending, Inc. of Denver, Colorado.
A preferred form of die set 11 is
illustrated in Figure 2 and is broadly comprised of a
bend die 34, a clamp die 35, pressure die 36 and wiper
die 37. Each of the dies 34 to 37 is of conventional
construction. For example, the bend die 34 is in the
form of a generally U-shaped block of hardened tool
steel or alloy steel, heat-treated and nitrided, a
tube groove 38 in its outer peripheral wall between
spaced, parallel top and bottom surfaces, and a semi-
circular end portion 34' as shown in Figure 1. The
clamp die 35 is in the form of a generally rectangular
block having a tube groove 39 in one side wall in
facing relation to one side of the bend die, the tube
groove 39 being complementary to the groove 38 in the
bend die. Typically the tube grooves of the bend die
34 and clamp die 35 are of generally semi-circular
configuration conforming to the size and configuration
of the tube T so that each encircles one-half of the
tube. ~ locking screw 42 in the clamp die holder 26
serves to adjust or tighten the clamp die 35 against
one side of the bend die 34 with the tube T interposed
therebetween during a tube bending operation.
The bend die includes a bore dimensioned to
,
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receive the upper end of the spindle 20 and a mounting
- plate 21 is keyed to the lower end of the spindle 20.
One or more jam nuts 23 are threaded onto the upper
end of the spindle 20 to retain the bend die 34
securely in position. The bottom surface of the die,
as shown in Figure 1, is recessed at 40 to define a
~ keyway aligned with a corresponding keyway in the
upper surface of the mounting plate 21 for the purpose
of receiving a key 40' when the dies are installed in
a manner to be described on the bending machine 10.
In normal practice, the clamp die 35 is individually
positioned on the clamp die holder 26 and, with the
tube T held in the bend die 34, the clamp die is
advanced by the clamp die holder 26 against the tube
and adjusted for vertical alignment as well as for
parallel contact with the entire length of the die 35
along the bend die 34.
The pressure die 36 is elongated and of
generally rectangular cross-section except for a tube
groove 44 along one side wall in facing relation to
the bend die tube groove 38 and a wiper die tube
groove 46. The pressure die 36 is aligned in end-to-
end relation to the clamp die and is advanced by the
pressure die holder 30 into engagement with the tube
T and adjusted for vertical alignment as well as for
constant pressure with the tube T along its length.
The wiper die 37 is typically employed when
a mandrel is required for the bending operation and is
of elongated configuration and of generally
rectangular cross-section but including the tube
groove 46 which engages the tube T on the same side as
the bend die 34. The wiper die 37 includes an arcuate
end portion 48 which is of a corresponding curvature
to the end portion 34' of the bend die 34 and is
advanced as far as pQssible into engagement with the
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bend die 34, then abutting or secured to a wiper die
holder 49. The wiper die holder is affixed in a
conventional manner to the ta~le 12 of the bending
mac~line 10 and has an upstanding leg to which the
wiper die may be secured by suitable fasteners.
Again, when individually used, the wiper die must ~e
adjusted for rake and vertical alignment.
The die set is completed by a mandrel 50
which is inserted into the tube and attached to the
leading end of the mandrel rod 18. Typically, the
mandrel 50 is made up of a series of balls which are
free to follow the curvature of the tube T when being
bent while supporting the interior wall surface of the
tube T to prevent collapse or wrinkling. Typically,
the mandrel must be inserted into the tube and
adjusted lengthwise by trial and error until the
optimum point of extension through the tube is
reached.
In the conventional die set as hereinbefore
described, the customary practice is to reassemble
each individual die 34-37 as well as the mandrel 50 in
position on the bending machine and follow the
necessary adjustment procedure to establish the
desired pressure on the tube to be bent as well as
vertical and tangential alignment of the dies and is
therefore time-consuming and results in substantial
downtime. In certain bending operations, a wiper die
is not re~uired and, for example, in some bending
applications it is not necessary to employ a wiper die
or mandrel, for example, as disclosed in our U.S.
Letters Patent No. 4,765,168 for MET~OD AND APPARATUS
FOR BENDING TUBING. In any event, depending upon the
particular tube ~ending requirements, the present
invention enables preassembly of the components making
up the die set so that the entire die set can be
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mounted on the spindle and properly aligned in a one-
step operation not requiring the preliminary
adjustment procedures as described. To this end, as
shown in Figure 2, the clamp die 35 and bend die 34
are releasably interconnected by draw latches 52
affixed to the top surfaces of the dies 34 and 35 at
longit~ lly spaced intervals across interfacing
edges of the respective members; or the edges may be
interlocked in a well-known ~nner. Preferably, each
latch 52 includes a keeper on the top surface of the
clamp die having a hooked end or return 54, and a
toggle-type latch member 55 affixed to the top surface
of the bend die 34 with a loop-shaped end 56 which can
be passed over the hook end 54 by pivoting of a toggle
member 57. The keeper 53 and latch 55 are permanently
affixed to the top surfaces of the respective ~mhers
by suitable fasteners, such as, screws, not shown.
Correspondingly, the pressure die 36 and wiper die 37
are releasably interconnected to one another by latch
members 52 at longitudinally spaced intervals.
Preferably, the latch elements 54 include an adjusting
mechanism to regulate the amount of pressure exerted
by the latch in drawing the dies together when in the
closed or latched position so that fine adjustments
can be made once the latches are permanently installed
or affixed onto the dies. In this relation, the
desired amount of pressure between dies is established
with an appropriate sized tube T inserted between the
interfacing or complementary tube grooves. One
suitable form of draw latch is the OJOP Latch sold by
Paul Moore Company of Cincinnati, Ohio, and it will be
evident that other forms of latches, clamps or bolts
may be utilized to retain the dies in their exact
aligned operating position with respect to one
another.
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As further shown in Figure 2, in
establishing vertical adjustment of the clamp die 35
and pressure die 36 with respect to one another and to
the bend die, a series of conventional hanger brackets
are provided including a clamp die hanger bracket 60
located somewha~ intermediately between the clamp die
latches 52, one side of the bracket 60 fastened to the
top surface of the clamp die and the other side
overhanging the clamp die holder 26. The fasteners
may take the form of vertical adjustment screws which
serve to properly position the clamp die with its top
surface flush with that of the bend die 34. In
addition, the clamp die bracket 60 includes a half-
round mounting shaft, not shown, which locates the
clamp die 35 in relation to tangent of bend. In a
similar manner, hanger brackets 60' are mounted on the
pressure die 36 at spaced longitudinal intervals with
overhanging portions of each hanger bracket affixed to
pressure die spacer bar 66, as shown in Figure 1.
Additionally, lift rings 68 are anchored at spaced
intervals to the dies 34-37 to facilitate lifting of
the die set onto and from the bending machine, such
as, by means of an overhead crane or a lift mechanism
of the type hereinafter described and shown in Figures
4 and 5.
In order to insert the mandrel 50 into the
tube to be bent, a mandrel locator 70 is mounted on
the end of the mandrel rod 18, as shown in Figure 3,
the locator 70 including a threaded counterbore 72 to
receive a threaded end of the mandrel rod 18 with a
lock nut 73 disposed at the entrance to the
counterbore. A second counterbore 74 is oppositely
directed to the first counterbore and somewhat
enlarged to receive a cylindrical extension 75 of the
mandrel 50. The mandrel itself is standard and
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includes a series of generally ball-shaped joints 76
as illustrated in Figure Z; and the extension 75 is
releasably attached to the locator 70 by a locking pin
78 exten~;~g transversely acrosc the counterbore 74
and through a transverse bore in the extension 75.
Suitable 0-rings 80 are disposed at opposite ends of
the locking pin as well as between the counterbore 74
and extension 75, and a lube passage 81 extends
centrally through the rod 18, intermedia~e wall of the
locator, extension 7~ and mandrel 50 to permit
injection of a suitable lubricant into the passages
80' leading to the outer periphery of the mandrel 50.
The mandrel locator 70 facilitates installation o~ the
mandrel into the tube to be bent and remains with the
preassembled die set so that all that is necessary is
to insert the cylindrical extension 75 into the
counterbore 74 and engage locking pin 78.
Various types of lift ?ch~nisms can be
employed for installation and removal of the die set
11 with respect to the bending machine. A lift
mech~n; ~r 84 is illustrated in Figures 4 and 5 having
an adapter frame 86 and a base 87 provided with spaced
openings 88 for insertion of tines F of a standard
forklift truck, not shown. An upper swivel mount 90
on the frame 86 carries a plurality of support arms
92, 93 and 94 for horizontal swinging movement about
the vertical axis of the swivel mount 90. Each of the
arms 92-94 carries radially spaced electromagne~s 96
each of which is suspended from a lift collar 98 and
adjustably secured to one of the arms 92-94 by lock
screws 99.
A locating key lOo is disposed at the
leading end of the base 87 in order to rapidly and
accurately locate the die set to a home position on
the bending machine. The locating key 100 is inserted
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into the keyway 40 of the bend die 34 to be placed or
installed on the bending machine with the
electromagnets 96 energized and brought into
engagement with the top surfaces of the bend die 34,
clamp die 35 and pressure die 36. The support arms 92
and 94 are disposed at 90~ from one another, and the
ele~LLo ~gnets 96 are adjusted along the length o~ the
respective arms to engage spaced surface portions on
the top surfaces of the dies 34 to 37. The
intermediate bar 93 may be employed when necessary to
balance heavy off-center die sets, and the
electromagnets 96 can be energized from the control
panel of the forklift. The lift mechanism 84 is
specifically adaptable for use in lifting die sets
without the necessity of placing lift rings 68 in the
die sets, for example, as shown in Figure 2.
In order to place or install a die set onto
the bending machine, the lift mPch~nism 84 is advanced
to a position above a selected die set in storage and
the support arms lowered until the electromagnets move
into engagement with the top surfaces of the dies 34-
37 as described. The electromagnets are then
energized and the die set lifted and transferred over
to the bending machine with the bend die 34 aligned
over the spindle 20 and the locating key 100 aligned
with the keyway 40. As the die set is lowered over
the spindle, the clamp and pressure die brackets 60
are lowered over their respective die holders which
have been advanced toward the bend die 34, and the
bend die 34 is secured in the usual manner to the
spindle 20 by one or more jam nuts 23. The mandrel
50, if required, is secured to the mandrel rod 16 in
the manner described. The wiper die 37, if required,
is secured to the wiper die holder 49 for radial
support. After the dies have been secured, the
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latches 52 are released and the clamp die 35 and
- pressure die 36 are retracted to a pre-bend position
following which the tube T is removed. If a mandrel
- was required for the particular die set selected, it
will have remained in the tube T and, as noted
earlier, is secured to the mandrel rod. The mandrel
50 is therefore retracted from the tube by the retract
cylinder 14 and the straight or bent tube T used to
help hold ~he die set together as an assembly is also
lo removed. A new tube T to be bent is inserted into the
die set and the mandrel 50 inserted into a new tube T.
In the manner described, each die set or
assembly is installed on the tube bending machine with
all of the dies in the same exact alignment as when
they were removed and therefore does not require the
customary individual locating and adjustment of each
of the dies. Accordingly, in a manner of minutes, the
installed die set is operational and tube bending
operations can be resumed. When the job is completed,
somewhat the reverse procedure is followed in the
removal of the die set from the bending machine.
Again, a bent or straight tube corresponding to the
size of tube T to be bent by the particular die set is
left in place, the latches 52 connected and the clamp
die and pressure die holders 26 and 30, respectively,
are released. Assuming that no lift rings 68 are
provided, the lift mech~ni~ 84 is advanced into
position over the die set and the arms 92 and 94
lowered into engagement with the top surfaces of the
dies. The lift collars on the arms 92 and 94 are
suitably adjusted to place their electromagnets 96 at
appropriate positions corresponding to the location of
the lift rings 68 as shown in Figure 2, and the
electromagnets are energized to lift the die set after
removal of the jamb nut(s) 23 from the spindle 20.
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14
The arms 92 and 94 are then raised to lift the die set
off of the bending machine table and the arms 92-~4
are rotated 90~ and the new tooling set lowered in
place on the bender as previously described. The
removed die set is transferred back to storage for the
next production run.
Another form of die set is illustrated in
Figures 6 to 8 which is of a type primarily designed
for large-radius tube bending. In this form, a
circular bend die 110 is mounted on a spindle 112, and
the bend die includes a circular tube groove 114 and
a clamp insert 116 provided with a tube groove 117
which extends tangentially of the tube groove 114. A
clamp die 120 and pressure die 122 are disposed
alongside the bend die 110 such that the clamp die
tube groove 123 and pressure die tube groove 124 are
aligned in facing relation to the bend die tube groove
114 as well as the insert tube groove 117. The wiper
die 126 having a tube groove 127 forms a tangential
extension of the insert 116. The tube grooves 123 to
124 are also aligned with one another along a common
tangent, and a tube T' is inserted between the facing
tube grooves 123, 124 and 117, 127.
The wiper die 126 is joined to the bend die
110 by a wiper die arm 128, the arm 128 being in the
form of a flat plate provided with an opening at its
forward end to receive an upper end of the spindle
112. The wiper die arm 128 extends rearwardly beyond
the rear edge of the spindle 112, and an L-shaped
crossbar 130 is attached to the rearward end of the
arm 128. The crossbar 130 extends transversely from
the arm 128 toward the wiper die 126 and has a
vertical leg 132 joined to the wiper die 126 by
fasteners 134 through slotted openings 135 into one
side of the wiper die 126. The upper horizontal leg
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136 of the crossbar 130 is secured to the wiper die
arm 128 by fasteners 138 exte~;ng through slotted
openings 139 of the leg.
The wiper die 12G is of the same type as
shown in Figure 2, it being understood that different
types of wiper dies can be used, such as, wiper die
tips, round-back wipers or self-sust~ g tip wiper
dies. The clamp insert 117 and wiper die 126 are
releasably interconnected to a clamp die 120 and
pressure die 122, respectively, by draw latches 52'
which correspond to the latches s2 shown in Figure 2
but are shown in the released position in Figure 6
after the die set has been installed on the spindle
112. Figure 6 also illustrates the mounting and
disposition of hanger brackets 60' between the top
surfaces of the clamp die 120 and clamp die holder 26'
as well as between the pressure die 122 and spacer bar
140 which is interposed in a well-known manner between
the pressure die 122 and pressure die holder 30.
Figures 7 and 8 illustrate in somewhat more
detail mounting of the die set of Figure 6 on the
spindle 112, the spindle including a generally sleeve-
like adapter 142 ext~n~ing upwardly from the lower
threaded end 143 of the spindle to upper threaded end
144. The upper end of the adapter 142 is externally
threaded to receive a jam nut 145 to securely affix
the wiper die arm 128 on the top surface of the bend
die 110 with compression bearings 147 and 148
therebetween. A spindle jam nut 150 is securely made
up on the threaded end 144 to fix the adapter 142
along with the wiper arm 128 and bend die 110 securely
in position with respect to the spindle 112.
It will be apparent from the ~oregoing that
stacked tool sets having two or more families of dies
of any size or shape can be removed, transferred and
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16
relocated on the bender as a complete assembly with
each die securely locked in a required bending
position to produce an acceptable bent part. Although
latches have been described for interconnecting the
die sets, it will be apparent that other types of
releasable interconnecting elements may be employed,
such as, clamps or bolts in retaining the dies in
exact aligned operating position with respect to one
another. If desired, suitable load cells, not shown
may be located behind the clamp and pressure dies, as
well as the wiper die, if used, that indicate the
optimum force required to produce an acceptable bent
part. Bend data records of the necessary forces for
specific bent parts facilitate accurate, ~uick clamp
1~ and pressure die pressure settings. The types of dies
sets herein set forth and described specifically in
relation to Figures 1, 2 and 7 to 9 are given more for
the purpose of illustration and not limitation and are
merely representative of various types of die set
assemblies that can be utilized in accordance with the
present invention.
It is therefore to be understood that while
preferred and modified forms of invention are herein
set forth and described, various modifications and
changes may be made therein without departing from the
spirit and scope of the present invention as appended
by the appended claims.
