Note: Descriptions are shown in the official language in which they were submitted.
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PRE-CRUSH DIE ASSEMBLY AND METHOD
Background of the Invention
The present invention relates to a pre-crush die assembly for
controlled deformation of a tubular member, such as, for example, a pipe or
conduit having a circular or non-circular cross-section, to be used in a
subsequent hydroforming operation.
Hydroforming is the known process of shaping usually a hollow tubular
metallic member within a closed mold by subjecting the hollow metallic
member to high internal fluid pressure. The high internal fluid pressure
permanently deforms the metallic member against the mold surfaces of the
closed mold. Hydroforming is used on a large scale for manufacture of frame
components for road vehicles and finds application in other manufacturing
and industrial processes where a tubular product is formed to very precise
dimensions.
One problem associated with hydroforming is known as pinching.
Pinching occurs when the outside walls of the tubular member are scraped
and deformed during insertion of the tubular member into the dies. Pinching
mostly occurs where the die cavity configuration will not accept, without
forced engagement, a tubular member that is bent to a considerable degree
and/or has a cross-sectional dimension considerably larger than that of the
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die cavity. This pinching may result in the walls of the tubular member
weakening and being subject to rupturing during the hydroforming process.
Accordingly, there is a need to provide a pre-crush tool that partially
deforms the tubular member prior to insertion of the tubular member into the
die cavity to prevent scraping and weakening of the wall of the tubular
member.
Brief Description of the Invention
In the present invention, a pre-crush die assembly is utilized for
controlled deforming of at least a portion of a tubular member to be used in a
subsequent hydroforming operation. The tubular member has a centerline
extending therethrough. The pre-crush die assembly comprises at least two
dies that move interdependently towards each other to deform the tubular
member on opposite sides thereof equally about the centerline of the tubular
member where the tubular member is being pre-crushed. The dies only act
against that portion of the tubular member to be pre-crushed and the dies do
not act against those portions of the tubular member not to be pre-crushed.
By interdependent movement it is meant that the dies are constructed
to move in unison towards and away from each other in opposing directions
of equal distance.
In one embodiment of the invention, a pre-crush die assembly is
utilized for controlling deforming of at least a portion of a tubular member
to
be used in a subsequent hydroforming operation. The tubular member has a
centerline extending therethrough and the pre-crush die assembly comprises
a support table and a sub-assembly. The support table supports the tubular
member relative therewith. The sub-assembly is mounted to the support
table for movement relative thereto. The sub-assembly comprises a first die
and a second die both adapted to move relative to the support table and
interdependently of each other between an open position and a closing
position deforming the portion of the tubular member. In the open position,
the first and second dies are positioned in spaced non-contacting relation to
opposing sides of the tubular member. The first and second dies move
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interdependently in opposing directions towards each other into the closing
position to continuously maintain the first and second dies equidistant from
the centerline of the tubular member adjacent the portion of the tubular
member being deformed.
It is envisaged that if the first and second dies are free to float relative
to the support table the first and second dies can self-align equidistant from
the tubular member as the two dies engage the tubular member.
Alternatively, the first and second dies are positioned in the open position
equidistant from the centerline of the tubular member adjacent the portion of
the tubular member to be deformed.
The term support table as used herein means any structure that is
capable of supporting the dies for relative movement with respect to one
another and the support table.
In an embodiment the first and second dies are the only dies utilized in
the pre-crush assembly. Alternatively the first and second dies may form one
die pair or one die of a set of dies used in the pre-crush assembly.
In another aspect there is provided a method of controlled deformation
of at least a portion of a tubular member to be used in a subsequent
hydroforming operation by first and second dies, the method comprises the
steps of:
positioning the tubular member between the first and second dies in
spaced non-contacting relation therewith; and
interdependently moving the first and second dies towards each other
to engage and deform the tubular member while continuously maintaining the
first and second dies equidistant from the centerline of the tubular member
adjacent the portion of the tubular member being deformed.
In one embodiment, the sub-assembly further comprises a first
carriage for supporting the first die and a second carriage for supporting the
second die. The support table comprises a guide trackway along which the
first and second carriages move.
In another embodiment, the first and second carriages each comprises
at least one elongate rail having an elongate groove extending along its
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length and the guide trackway comprises guide members mounted to the
support table each having an edge surface portion extending into and along
the elongate groove of the elongate rail.
In one embodiment, the sub-assembly comprises a first set of rails
adapted to slide relative to the support table, a second set of rails
interspaced
with the first set of rails and adapted to slide relative to the support table
in
directions opposite to those of the first rails. The first die is mounted to
the
first set of rails, and the second die is mounted to the second set of rails.
In another embodiment, the sub-assembly further comprises a first
mounting plate connected for movement with the second set of rails and at
least one first hydraulic cylinder mounted to the first mounting plate and
coupled with the first die. The at least one first hydraulic cylinder is
adapted
to expand and contract causing during expansion the first and second dies to
move interdependently, via the first mounting plate and the first and second
rails into the closing position.
In another embodiment, the sub-assembly is a closed loop sub-
assembly further comprising a second mounting plate connected for
movement with the first set of rails spaced along the first and second rails
from the first mounting plate. The sub-assembly further comprises at least
one second hydraulic cylinder mounted to the second mounting plate and
coupled with the second die. The at least one second hydraulic cylinder is
adapted to expand and contract in unison with the expansion and contraction
of the at least one first hydraulic cylinder whereby expansion of the at least
one second hydraulic cylinder causes the first and second dies to move
interdependently, via the second mounting plate and the first and second rails
into the closing position. It is envisaged that the second hydraulic cylinder
is
connected either directly to the second die or indirectly to the second die in
the event the second die comprises a second slave die.
In another embodiment the first and second rails each have an
elongate groove extending along its length and the support table has fixedly
mounted thereto guide members each having edge surface portions slidingly
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extending into and along the elongate groove of each of the first and second
rails.
1n yet another embodiment, the pre-crush die further comprises at least
one drive coupler mechanically coupling the first and second rails whereby
the first and second dies are further maintained equidistant from the
centerline of the tubular member adjacent the portion of the tubular member
to be deformed during interdependent movement of the first and second dies
and first and second rails. The drive coupler in effect improves the tolerance
of accuracy in the interdependent movement of the first and second dies.
In another embodiment the at least one drive coupler comprises a first
toothed rack mounted to the first rail, a second toothed rack mounted to the
second rail, and a toothed pinion mounted to the support table for rotation
therewith. The toothed pinion is mounted in meshing relation with the first
and second toothed racks.
Brief Description of the Drawings
For a better understanding of the nature and objects of the present
invention reference may be had by way of example to the accompanying
diagrammatic drawings.
Figures 1A and 1 B are schematic drawings of the present invention;
Figure 2 is a perspective view of an embodiment of the present
invention;
Figure 3 is a partial perspective view of the sub-assembly of the
embodiment of Figure 2; and,
Figure 4 is another partial perspective view of the sub-assembly of the
embodiment of Figure 2.
Detailed Description
The present invention relates to a pre-crush die assembly for
controlled deformation of a tubular member, such as, for example, a pipe or
conduit having a circular or non-circular cross-section, to be used in a
subsequent hydroforming operation.
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Referring to Figures 1 A and 1 B there is shown a schematic view of the
pre-crush die sub-assembly 10. The sub-assembly 10 comprises a first die12
and a second die 14. The dies 12 and 14 are carried by carriages 16 and 18
respectively. Each of the dies 12 and 14 has a corresponding hydraulic
cylinder 20 and 22 coupled to it. The hydraulic cylinders 20 and 22 each
have a cylinder portion 24 and a piston portion 26 and are run by a hydraulic
power pack (not shown). The piston portion 26 is coupled to the
corresponding die 12, 14. The cylinders 24 of each of the hydraulic cylinder
is 20, 22 is connected to a corresponding carriage 16, 18. In this manner, a
closed loop sub-assembly 10 is provided. In the open position shown in Fig
1 B, a tubular member 30 is shown located between the die faces 11, 13 of
dies 12 and 14. The tubular member 30 has a centerline 32 that is positioned
equidistant from each of the die faces 11, 13 of dies 12 and 14. During the
expansion of the hydraulic cylinders 20 and 22, the dies 12 and 14 are moved
into a closed or closing position whereby the die faces 11, 13 of the dies 12,
14 engage and deform corresponding surface portions 15, 17 of the tubular
member 30. The expansion of the hydraulic cylinders 20, 22 also acts on the
carriages 16 and 18 to push the carriages apart resulting in the die faces 11,
13 of the dies 12 and 14 moving towards each other in opposing directions to
continuously maintain the first and second dies 12, 14 equidistant from the
centerline 32 of the tubular member 30.
In Figures 1A and 1B, the pre-crush die sub-assembly 10 has been
shown to be free floating. It should be understood that this sub-assembly
would normally be mounted to a support table (not shown) for sliding
movement with the support table. In this respect, the support table would
include trackways along which the carriages 16 and 18 would travel in a
guided manner.
Referring to Figures 2 through 4, there is shown a pre-crush die
assembly 40 for controlled deformation of a first tubular member 42 and a
second tubular member 44. The tubular members 42 and 44 each have a
respective centerline 46 and 48 shown in dotted line extending through the
tubular member. The tubular members 42 and 46 are shown to comprise
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bent pipe of similar configuration. The end portions 50 of the tubular
members 42 and 44 are shown mounted within fastening devices or
releasable clamp devices 52. The clamp devices 52 are provided with a
receiving cradle 54 into which the tubular members 42 and 44 are received.
The clamp device 52 has an arm member 56 that is adapted to move into a
clamping position with the tube end portions 50. The clamping devices 52 are
positioned on support table 58 so as to support the first and second tubular
members 42 and 44 relative with and to the support table 58. As shown in
Figure 1, the first and second tubular members 42 and 44 are supported
relative with the support table 58 above a top plate 64.
The support table 58 comprises a base frame structure 60 that
includes legs 62. Mounted to the top of the base frame structure 60 is a top
plate 64. The top plate 64 has a series of wear plates 66 mounted thereon.
In particular, the wear plates 66 extend from the end portions 72 of the top
plate 64 and terminate before the middle of the top plate 64. Each of the
wear plates is held in place by guide members or guide brackets 68 which are
secured by means of bolts 70 that pass through the guide brackets 68 and
wear plates 66 and through the top plate 64 of the support table 58. Each of
the guide brackets 68 has a protruding track edge portion 74, the purpose of
which will be described hereinafter.
A closed loop sub-assembly 80 is mounted relative to the top plate 64
of the support table 58 for movement relative to the support table 58.
The sub-assembly includes a first set of two rails 82 and a second set
of three rails 84 inter-spaced from the first set of rails 82. Each of the
rails 82
and 84 is adapted to rest and slide on two wear plates 66 whereby the length
of the rails 82 and 84 extend across and move along the length of the support
table top plate 64. Each of the rails 82 and 84 is adapted to slide relative
to
two rail plates 66. Each of the rails 82 and 84 has an elongate groove 86 that
extends along the length of the rail. The track edge portion 74 extends into
the recessed groove to limit the sliding motion of the rails 82 and 84 in
opposing directions along the length of the support table 58.
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The second set of rails 84 are interconnected by a first mounting plate
88. The first mounting plate 88 is provided with a series of bolts 90 that
extend through the first mounting plate 88 and are secured within threaded
apertures in the second set of rails 84. Accordingly, the first mounting plate
88 acts to group the second set of rails 84 for uniform motion.
A second mounting plate 100 is mounted to the first set of rails 82 by
means of bolts 102 that pass through the surface of the second mounting
plate 100 and the threaded apertures located in the first set of rails 82. In
effect, the second mounting plate 100 acts to group the first set of rails 82
and for uniform motion.
The sub-assembly 80 further includes two spaced apart servomotors
104 that are mounted to the first mounting plate 88. Servomotors 104 have a
cylinder portion 106 and a piston portion 108. The hydraulic cylinders 104 are
in effect hydraulically driven piston cylinders. The cylinder 106 of the
hydraulic cylinders 104 are each connected by a frame bracket 110 which is
secured by bolts 112 to the first mounting plate 88.
Similarly, a pair of second hydraulic cylinders 114 are mounted to the
second mounting plate 100. The second hydraulic cylinders 114 comprise a
cylinder portion 116 and a piston portion 118. The second hydraulic cylinders
114 are surrounded by a frame bracket 120 and connected to the second
mounting plate 100 by bolts 122.
The closed loop sub-assembly 80 further comprises a first master die
124 and a first slave die 126 mounted to the first set of rails 82 between the
first and second mounting plates 88, 100. The first master die 124 and the
first slave die 126 are mounted by suitable means, such as, for example bolts
123 passing through the first set of rails 82 and into the dies 124, 126 or
alternatively the dies 124, 126 have protruding key members that are inserted
into receiving slots in the rails (124, 126).
The closed loop sub-assembly 80 further comprises a second master
die 128 and a second slave die 130 mounted to the second set of rails 84
between the first and second mounting plates 88, 100.
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By mounting of the first master die 124 and the first slave die 126 to
the first set of rails 82, the first master die 124 and the first slave die
126 are
adapted to move in unison relative to each other with the first set of rails
82.
By mounting the second master die 128 and the second slave die 130 to the
second set of rails 84, the second master die 128 and the second slave die
130 are adapted to move in unison with each other and with movement of the
second set of rails 84.
The pistons 108 of the first hydraulic cylinders 104 are connected via a
bracket 132 to the first master die 124. Similarly, the piston 118 of the
second hydraulic cylinders 114 are each connected through a bracket 134
with the second master die 128.
As shown in Figure 2, the first master die 124 has a punch surface 136
opposite to a punch surface 138 of the second slave die 130. Similarly, the
first slave die 126 has a punch surface 140 that is opposed to or across from
the punch surface 142 of the second master die 130. Punch surfaces 136
and 138 may be said to be complimentary to each other as they will in effect
have opposing contours. For example where the contour of one die punch
surface is concave the other would be convex. Similarly, each of the punch
surfaces 140 and 142 of the first slave die 126 and second master die 128
are complimentary.
During operation, the first and second tubular members 42 and 44 are
secured by the clamping devices 52 with the closed loop sub-assembly 80 in
its open position. This is shown substantially in Figure 2. In the open
position, the first master die 126 and the second slave die 130 are positioned
on opposing sides of the first tubular member 42. The first master die 124
and the second slave die 130 are spaced in non-contacting relation to the
first
tubular member 42 equidistant from the centerline 46 of the first tubular
member 42 adjacent the portion of the first tubular member 42 to be
deformed. By the portion it is meant that the first master die 124 and the
second slave die 130 may not deform the entire length of the tubular member
42 but only selected portions of this member 42. As a consequence it is only
necessary that the punch surfaces of the first master die 124 and the second
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slave die 130 that come into contact with the portions of the first tubular
member 42 be maintained equidistant from the centerline 46 of the first
tubular member 42 adjacent that portion to be deformed.
The second master die 128 and the first slave die 126 in the open
position shown in Figure 2 are positioned on opposing sides of the second
tubular member 44 in non-contacting relation therewith. The second master
die 128 and the first slave die 126 are positioned equidistant from the
centerline 48 of the second tubular member 44 adjacent the portion of the
second tubular member 44 to be deformed.
Once the clamping device 52 indicates that all end portions 50 of the
first and second tubular members 42, 44 are clamped in place, such as for
example by the use of limit switches 200, then the closed loop sub-assembly
is operated to pre-crush the tubular members 42 and 44. This is
accomplished by actuating the first and second hydraulic cylinders 104 and
114 at the same time to expand causing the pistons 108 and 118 to push
against the first master die 124 and the second master die 128. At the same
time the first mounting plate 88 may be displaced in a direction opposite to
the expansion of the first piston 108. Simila~iy, the second mounting plate
100 may be displaced in a direction opposite to the expansion of the piston
118. This is due to the closed loop effect of the first and second mounting
plates 88 and 100 being mounted to the second and first set of rails 84, 82,
respectively. Consequently the first master die 124 and the second slave die
130 move interdependently of each other via the first and second mounting
plates 88, 100 and the first and second rails 82, 84 in opposing directions
towards each other into a closing position engaging and deforming the first
tubular member 42. During this interdependent movement the first master die
124 and the second slave die 130 remain equidistant from the centerline 46
of the first tubular member 42 adjacent the portion of the first tubular
member
42 to be deformed. Similarly, the second master die 128 and the first slave
die 126 move interdependently of each other, via the first and second
mounting plates 88, 100 and the first and second sets of rails 82, 84, in
opposing directions towards each other into the closing position to deform the
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second tubular member 44. The second master die 128 and the first slave
die 126 remain equidistant from the centerline 48 of the second tubular
member 44 adjacent the portion of the second tubular member 44 being
deformed as the second master die 128 and the first slave die 126 move from
the open position to the closing position.
Additional limit switches (not shown) are utilized in order to determine
when the dies have reached their closing positions. Thereafter, the hydraulic
cylinders 104 and 114 may be contracted to move the dies from a closed
position back into an open position which is again monitored by limit switches
(not shown). At this time, the clamping devices 52 may be released to allow
the removal of the pre-crushed tubular members 42 and 44 from the die
assembly 40.
To further limit the closing of the dies, the table top plate 64 has an
end bracket 146 to which stops 148 are attached. The stops 148 at each end
of the support table 58 are adapted to engage one of the sets of rails 82, 84
that move towards the corresponding stops 148 to thereby limit movement of
the rails 82, 84 during the closing operation. The stops 82, 84 provide a
positive mechanical stop movement for the rails 82, 84. Mounted to the top of
each of the brackets 146 are protection guards 150.
It should be understood that the embodiment described deals with a
first master die and a second slave die. It is envisaged that more than one
slave dies could be utilized so that more than two tubular members could be
deformed at the same time. Alternatively, only master dies directly coupled to
the hydraulic cylinders may be utilized so that only a single tubular member
is
pre-crushed.
While the present invention provides for a uniform crushing of a tubular
member about the tubular members centerline, to improve the tolerance of
this symmetrical crushing about the centerline of the tubular member, the
embodiment further employs as shown in Figure 4 a pair of drive couplers
152 which mechanically couple one rail of each of the first and second sets of
rails 82, 84 so that the first master die 124 and first slave die 126 and the
second master die 128 and second slave die 130 are further maintained
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equidistant from the centerlines 46, 48 of the tubular members 42, 44 during
deformation. Each of the drive couplers 152 comprises a first tooth rack 160
mounted to one of the first set of rails 82 and a second tooth rack 162
mounted to one of the second set of rails 84. The drive coupler 156 further
includes a tooth pinion 166 mounted for rotation at axis 167 with the support
table 58 via plate 168. The teeth of the pinion 166 is located in meshing
relation with the teeth of the first and second toothed racks 168. As a
consequence, opposing motion of the first set of rails 82 relative to the
second set of rails 84 is governed by this drive coupler 156 to improve the
tolerance of the relative movement of the dies.
While the invention has been described in terms of various specific
embodiments, those skilled in the art will recognize that the invention can be
practiced with modifications within the spirit and scope of the claims.
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