The present invention relates to a hydroforming seal apparatus and method and more particularly a two mode hydroforming seal and method by which the hydroforming cycle time can be shortened while making high quality hydroformed tubes.
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 hydroforming dies having cavities which define the desired resultant shape of the tube. Pressurized hydroforming fluid is then introduced into the tube to expand the tube outwardly into the cavities.
It often occurs that the complex shape of the cavities require that the tube be preformed to an approximate shape of the cavities before the tube is placed into the dies. The prior art has recognized that the pre-forming of the tube can be avoided by positioning the tube between the dies and then filling the tube with fluid under a modest pressure so that the dies can then be closed and the pressure of the fluid residing within the dies will provide sufficient internal support to the tube walls to thereby prevent undesired collapse or other injury to the tube as the tube is forced into the cavities by the closing dies. Thus, although the pre-filling of the tube before closing the dies can avoid the necessity for pre-forming the tube, the hydroforming seals can be subjected to increased stress and wear which can cause an increase in machine down time for seal maintenance.
It is also well known that the complexity of the cavities in the hydroforming dies can result in the need to axially feed the tube into the die cavity as the hydroforming pressures are increased to expand the tube outwardly into the conformance with the complex shapes of the die cavity. This axial feeding under high pressure condition can also cause stress and wear on the seals.
In view of the foregoing, it would be desirable to provide further improvements in hydroforming seals and methods in order to achieve further improvements in the reliability of the sealing of the ends of the tubes as well as improved cycle times for the filling of the tube, and the closing of the dies, and the introduction of high pressure fluid and axial feeding of the tube into the complex shape of the dies.
A hydroforming seal and method includes a nozzle for insertion into the tube, the nozzle being a radially expandable O-ring seal for sealing with the bore of the tube, a conical tapered surface for sealing with the bore of the tube, and a radial shoulder for engagement with the end of the tube. The O-ring seal is expanded to seal the tube and pressurized fluid is added sufficient to support the interior of the tube while the dies are closed and the tube is thereby bent and forced into the die cavity without collapse or injury to the tube by the closing dies. The O-ring seal is then contracted to a non-sealing position and the conical tapered surface provides metal-to-metal sealing while the hydroforming pressure is applied to expand the tube outwardly into the die cavities and the end of the tube is axially fed into the die by the engagement of the radial shoulder with the end face of the tube.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of certain exemplary embodiments is merely exemplary in nature and is not intended to limit the invention, its application, or uses.
Referring to
A seal unit, generally indicated at 26, is mounted on the lower bed 12 of the press 10 by an elevator mechanism 28 that includes an elevator base 32 supported on springs 34. The seal unit 26 has a housing 36 mounted on the elevator base 32 and made of a sleeve 37, right end cap 38 and left end cap 39 that are bolted or welded together. The housing 36 has a cylinder bore 42. A feed piston 44 slides inside the cylinder bore 42 and has a feed rod 46 attached to the feed piston 44 and extending toward the hydroforming dies 16 and 18. The feed rod 46 carries a nozzle unit, generally indicated at 48.
The nozzle unit 48 is best seen in the enlarged view of
The seal actuator 62 has a central fluid bore 92 that communicates with a central fluid bore 94 provided in the rod portion 74 of piston 66. A pipe 96 is connected to the central fluid bore 94 so that hydroforming fluid can be introduced into the tube 22, as will be discussed in detail hereinafter.
The leftward end of the seal actuator 62 has a groove 98 formed by a cylindrical wall 100 and a conical ramp 102. An elastomeric o-ring seal 106 resides in the groove 98. The leftward end of the nozzle housing 52 has a conical ramp 108 that faces toward the conical ramp 102 of the seal actuator 62.
The leftward end of the nozzle housing 52 also has a cylindrical tapered seal surface 110 that is sized to be press fit into the end face 24 of the tube 22, and a radial shoulder 112 that will press against the end of the tube 22 when the cylindrical tapered seal surface 110 is pressed into sealing engagement with the bore 23 of the tube 22. As seen in
Referring again to
In
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Thus, it is seen that a dual mode nozzle has been provided in which an elastomeric O-ring seal is used to seal the end of the tube during the relatively lower fluid pressures needed to support the interior of the tube during the forced lowering of the tube 22 into the cavities of the hydroform dies 16 and 18. The metal-to-metal seal provided by the tapered conical seal surface 110 and radial shoulder 112 will be relied upon to seal the tube at the substantially higher fluid pressures that are required to hydroform and expand the tube into its final shape. By contracting the O-ring seal away from the tube during the high pressure hydroforming, the life of the O-ring seal can be substantially improved as it is not employed to obtain sealing at the relatively much higher pressures used in the hydroforming and axial feeding. During the closing of the dies, the O-ring seal 106 has sealing capability and a sufficient flexibility to accommodate some movement of the tube as it is force fed into the die cavities upon the closure of the upper die 18.
It will be understood that the particular metal-to-metal seal shown herein is just one example of the metal-to-metal seals known in the prior art, and that the invention herein is not limited to the particular example of a metal-to-metal seal shown herein. In some cases, the radial shoulder 112 will be stepped or otherwise shaped to effectively seal against the end face 24 of the tube.
Number | Name | Date | Kind |
---|---|---|---|
4393674 | Rasmussen | Jul 1983 | A |
5233854 | Bowman et al. | Aug 1993 | A |
5357774 | Klages et al. | Oct 1994 | A |
5445002 | Cudini et al. | Aug 1995 | A |
5511404 | Klages et al. | Apr 1996 | A |
6397449 | Mason et al. | Jun 2002 | B1 |
6532785 | Gmurowski | Mar 2003 | B1 |