External seal device for tube hydroforming

A seal device for a hydroforming press includes a housing having a bore and a seal carrier slidable within the housing bore. The seal carrier has a bore which fits closely outside of the end of tube to be hydroformed. A V-shaped locator rigidly mounted relative to the housing aligns the end of the tube placed thereon with the carrier bore. A carrier actuator is operable to move the seal carrier between a retracted position away from the end of the tube to an extended position over the end of the tube. A resilient elastomeric annular seal carried by the seal carrier encircles the outer surface of the tube. A seal actuator carried on the seal carrier compresses the seal upon relative movement between the seal actuator and the seal carrier. A stop is engaged by the seal actuator as the seal carrier approaches the extended position so that subsequent further movement of the seal carrier compresses the seal against the tube. The locator and a tube backup fixed to an upper bed of the press encircle the tube when the press is closed, reacting against the tube when it is pressurized. A travel limit block provides a reaction member against which the locator reacts to prevent relative movement between the seal device and the press during forming.

TECHNICAL FIELD 
This invention relates to a seal device for sealing engagement on the outer 
surface of a tube in a hydroforming press. 
BACKGROUND OF THE INVENTION 
It is well known, in the prior art, that a tube may be hydroformed to a 
desired complex tubular shape. The tube is placed between a pair of dies 
having cavities which define the desired resultant shape of the tube. The 
ends of the tube are accessible through the die and a seal is connected to 
the ends of the tube so that pressurized fluid injected into the tube 
forces the tube to expand and conform to the shape defined by the die 
cavity. It is also known to mount the dies in a press so that a lower die 
is stationary on the lower bed of the press and the upper die moves up and 
down with the upper bed of the press to permit loading and unloading of 
the tubes from the die. 
U.S. Pat. No. 5,233,054, assigned to the assignee of this invention, 
provides improvements in the press apparatus and in the mounting of a seal 
unit or seal device on the press. U.S. Pat. No. 5,233,856, assigned to the 
assignee of this invention, provides an improved seal device for sealing 
engagement on the outer surface of the tube end in a hydroforming process. 
U.S. patent application Ser. No. 08/071,411, filed Jun. 4, 1993, assigned 
to the assignee of this invention, entitled "External Seal Device for 
Hydroforming" also discloses a similar seal device having an actuator with 
a removable end facilitating seal replacement. 
The present invention provides a new and improved seal device having 
locator means for aligning the tube end with the seal device. 
SUMMARY OF THE INVENTION 
A seal device sealingly engages on an outer surface of an end of a tube to 
be hydroformed within a die cavity formed between a pair of dies. The seal 
device includes a seal carrier having an opening adapted for close fitting 
installation over the end of the tube. A carrier actuator is operable to 
move the seal carrier between a retracted position withdrawn away from the 
end of the tube and an extended position in which the seal carrier is 
installed over the end of the tube. 
A V-shaped locator is linked by mounting means to the seal carrier and has 
surfaces aligning the end of the tube placed thereon with the opening of 
the seal carrier. A resilient elastomeric annular seal is carried by the 
seal carrier within the opening thereof and encircles the outer surface of 
the tube. A seal actuator is slidably carried on the seal carrier and is 
adapted to compress the seal upon relative movement between the seal 
actuator and the seal carrier so that the seal is forced radially inward 
to sealingly engage the outer surface of the tube. A stop element is 
engaged by the seal actuator as the seal carrier approaches the extended 
position so that the seal actuator is stopped against further movement and 
further movement of the seal carrier to the extended position then 
compresses the seal about the outer surface of the tube.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
U.S. Pat. No. 5,233,854, filed May 29, 1992, assigned to the assignee of 
the present invention is hereby incorporated by reference. 
A press has a first or lower die 10 and a second or upper die 12 mounted to 
corresponding lower and upper press beds 14 and 16. The press is operable 
to move the second die 12 along a first axis 18 between an open position 
shown in FIG. 1 and a closed position shown in FIG. 2. With the second die 
12 in the open position, a tube 20 to be hydroformed is held between the 
first and second dies 10, 12 by a robot or other suitable mechanism. A 
seal unit or seal device 22, is provided for sealing engagement on an 
outer surface 24 of an end of the tube 20 and for communicating pressure 
fluid into the tube 20. 
An elevator 26 is suspended above the lower press bed 14 by springs 28 
between the elevator 26 and the press bed 14. 
A housing 30 of the seal device 22 is rigidly mounted to the elevator 26. A 
seal carrier 32 is slidably disposed within a cylindrical bore 34 in the 
housing 30. The seal carrier 32 has a carrier bore 36 adapted to closely 
fit over the end of the tube 20. 
A carrier actuator 38, such as might be provided by a hydraulic cylinder, 
operably moves the seal carrier 32 between a retracted position (not 
shown) withdrawn away from the end of the tube 20 and an extended 
position, as in FIG. 1 and FIG. 2, in which the seal carrier 32 is 
installed over the end of the tube 20. 
A seal actuator 100 is slidably carried on the seal 32 and is limited in 
available axial travel relative to the seal carrier 32 by a stop bolt 102 
projecting radially inward from the seal actuator and slidably received in 
a slot 104 in the seal carrier. An annular, resilient elastomeric seal 106 
is captured between a distal end 108 of the seal carrier and a radially 
inward directed annular lip 110 at outboard end 112 of the seal actuator 
100. The seal actuator 100 engages a stop element 114 rigidly mounted on 
the elevator 26 before the seal carrier 32 achieves its extended position 
so that further movement of the seal carrier to its extended position 
compresses the seal 106 inwardly to sealingly engage the outer surface of 
the tube 20. 
The seal carrier 32 has an annular tube support 40 mounted within the 
carrier bore 36 to extend inside the tube 20 when the seal carrier 32 is 
extended. 
A filter comprising a sieve element 42 disposed between two reinforcing 
plates 44, 46 is optionally mounted within the annular tube support 40. 
The plates 44, 46 each have a plurality of apertures 48 in alignment with 
the apertures 48 in the other plate. 
A V-shaped locator 50, best seen in FIG. 3, is rigidly mounted to the 
elevator 26 between the housing 30 and the dies 10, 12. The V-shaped 
locator 50 has surfaces 51 which align the end of the tube 20 placed 
thereon with the carrier bore 36. The locator 50 is open toward the second 
die 12. The V-shaped locator 50 also has a rounded bottom 53 complementary 
to the tube 20. 
A tube backup 52, best seen in FIG. 3, is fixed relative to the second die 
12 and has a concave surface 54 complementary to the tube 20 aligned with 
and facing the open V-shaped locator 50. 
A travel limit block 56, shown in FIG. 1 and FIG. 2, is fixed relative to 
the first die 10, underneath the elevator 26 with the springs 28 and 
generally in line with the locator 50. 
The seal device 22 operates as follows. The robot loading the tube 20 into 
the press lowers the end of the tube 20 onto the V-shaped locator 50. 
Tangential contact between the tube 20 and the V-shaped locator 50 
positions the end of the tube 20 with respect to the carrier bore 36. 
The carrier actuator 38 moves the seal carrier 32 over the end of the tube 
20. The seal device 22 sealingly engages an outer surface 24 of the tube 
20, as shown in FIG. 1 and FIG. 2. 
The second die 12 moves from the open position downward toward the closed 
position. A pusher block 58, moving with the second die 12, engages the 
housing 30, so that with continued movement of the second die 12 to the 
closed position the seal device 22, elevator 26 and the V-shaped locator 
50 will be moved downward as a unit with the second die 12 as the springs 
28 permit. This continues until the second die 12 reaches the closed 
position. With the second die 12 in the closed position, the V-shaped 
locator 50 and the tube backup 52 encircle the tube 20 therebetween. This 
puts an underside 60 of the elevator 26 very close to or in contact with 
the travel limit block 56. 
The tube 20 is filled with hydraulic fluid. Fluid entering the tube 20 
passes through the filter in the annular tube support 40. When the 
hydraulic fluid in the tube 20 is pressurized, the tube 20 reacts against 
the encircling tube backup 52 and V-shaped locator 50. The tube backup 52 
directs its portion of the reaction into the upper bed 16 of the press. 
The V-shaped locator 50 directs its portion of the reaction into the 
elevator 26, which in turn reacts principally against the travel limit 
block 56, and ultimately against the lower bed 14 of the press. The travel 
limit block 56 prevents further spring deflection, thereby maintaining the 
position of the elevator 26 and the seal device 22 during high pressure 
forming. 
After the tube 20 has been hydroformed, the fluid in the tube 20 is drained 
off through the seal carrier 32, passing through the filter which protects 
fluid controls from debris suspended in the returning fluid. 
The improved positioning provided by the V-shaped locator 50 offers a cost 
benefit which can be realized by permitting more generous tolerances for 
any required bending of tubes to be hydroformed and for the positioning of 
the tube 20 between the dies 10, 12 by the robot.