MANDREL WITH ELASTIC SLEEVE UTILIZING HYDRAULIC PRESSURE FOR HYDROFORMING HOLLOW METAL CYLINDERS

Abstract

A mandrel with an elastic sleeve utilizing hydraulic pressure for hydroforming hollow metal cylinders is disclosed. This invention simplifies the manufacturing process of the hydroforming device and reduces the associated cost, through the use of fluid pressures upon the elastic sleeve that biases forcefully against the interior of the metal cylinder being shaped. In the case where containment of the hydorforming fluid is desired, so as to prevent any contamination of the interior of the cylinder being shaped, this technology can provide that containment more reliably. The elastic sleeve material used is reasonably flexible, and more durable than other materials used in related devices.

Description

FIELD OF INVENTION

This invention relates to the use of fluid pressures to radially hydroform a metal cylinder into the precise shape and dimensions required for the finished product, including an elastic sleeve that expands against the interior of the cylinder to attain its precise required dimension.

BACKGROUND OF THE INVENTION

When using a fluid to radially hydroform a metal cylinder, it is often desirable to keep the fluid self-contained for various reasons including but not limited to contamination of the material to be formed, loss of a valuable fluid, or contamination of surrounding environment with said fluid.

Other methods for hydroforming metal cylinders can be more expensive and complex to manufacture. Other methods for hydroforming may also not contain the fluid used for the hydoforming process. Many forms of apparatus used to hydroform metal cylinders rely on a soft material such as an O-ring to be in intimate contact with the mandrel OD and the cylinder ID before, during and after hydroforming. This can lead to considerable resistance and require high amounts of force to insert and remove the apparatus. The O-rings are vulnerable to cuts and tears during the insertion process which leads to premature O-ring failure and insufficient retention of the pressure required to hydroform the metal cylinder.

The inventor herein has obtained various prior United States patents relating to the technology of a System and Method for Radially Expanding Hollow Cylindrical Objects, such as can be seen in his U.S. Pat. No. 9,468,966. He has also obtained U.S. Pat. No. 9,027,601, upon Hydraulically Installed Tube Plug, Tube Plug Installation Tooling, and Installation System and Method.

SUMMARY OF THE INVENTION

This invention contemplates the hydroforming of hollow metal cylinders, and attains such through the expansion of an elastic sleeve maintained within the cylinder and subjected to substantial fluid compression for attaining the reshaping of the subject's cylinder from the use of hydraulically stimulating pressures through the application of the subject matter and mechanics of this invention.

The present embodiment accomplishes the above objectives. The apparatus utilizing an elastic sleeve does not rely on trapped fluid between the mandrel OD and the cylinder ID to hydroform the cylinder. There are no O-rings or soft seal materials required to be in intimate contact with the cylinder ID prior to introducing the fluid for the hydroforming process or after its completion. This eliminates the requirement for soft seal material in the annular space between the apparatus and the metal cylinder that is to be hydroformed along with the issue of cuts and tears associated with such soft materials. This also eliminates the high forces that may be required to insert and remove the hydroforming apparatus.

It includes a hard metal mandrel shaft inside an elastic sleeve. The mandrel shaft shall provide a means of positioning and retaining the elastic sleeve in a precise location axially along the mandrel in itself thus defining an expansion zone. Preferably this will be accomplished with a combination of bushings and locking nuts and manufactured from an inelastic material such as metal. The mandrel shaft shall have an axial path in its center intersecting with a radial path that exits within the boundaries of the elastic sleeve. This path will be used as a means of introducing pressurized fluid into the annular space between the mandrel OD and the elastic sleeve ID. The mandrel shaft will have an annular grooves located between the source of the pressurized fluid exiting the mandrel shaft and prior to each end of the elastic sleeve. A soft elastic material such as an O-ring shall reside in the annular groove to provide a seal between the mandrel shaft OD and the elastic sleeve ID.

In the case where containment of the hydroforming fluid is desired, this technology can provide that containment more reliably. The elastic sleeve material used is more durable than other materials used in similar devices, thus allowing more expansions, and reducing the amount of unproductive time spent replacing tooling parts. This embodiment simplifies the manufacturing process of the hydoforming device and reduces the associated cost. Other features and advantages of the embodiment will become more apparent in the following drawings and detailed description.

The object of this invention is to eliminate the need for soft material seals between the expansion apparatus OD and the ID of the metal cylinder by radially hydroformed along with the concern for cuts and tears associated with the use of these seals. To reduce the operator fatigue associated with inserting and removing an apparatus that utilizes the soft seals previously discussed. To provide an apparatus that contains the pressurized fluid during operation and returns it automatically to its source when the pressure is reduced. To reduce the cost of manufacturing by simplifying the design of the apparatus and increase the reliability.

Other objects and purposes for the subject matter of this invention may occur to those skilled in the art upon review of the disclosure as provided herein. Such variations, if within the spirit of this invention, are intended to be encompassed within the scope of any claims to patent protection issuing from this application.

BRIEF DESCRIPTION OF THE DRAWINGS

In referring to the drawings:

FIG. 1 is an exploded prospective view of a disassembled mandrel assembly;

FIG. 2 is a longitudinal cross section of a mandrel assembly positioned in a tube located in a tube sheet ready to begin expanding;

FIG. 3 is an enlarged longitudinal cross section of the overlapping mating surfaces of an elastic sleeve and a sleeve retaining bushing;

FIG. 4 is a longitudinal cross section of the overlapping mating surfaces of an elastic sleeve and a sleeve retaining bushing described in the second embodiment; and

FIG. 5. is a longitudinal cross section of the overlapping mating surfaces of an elastic sleeve and a sleeve retaining bushing described in the third embodiment.

VARIOUS COMPONENTS OF THE INVENTION

• M. Mandrel Assembly
• 1. Mandrel Shaft
• 2. Reduced OD of Mandrel Shaft between Annular Grooves
• 3. 3a & 3b—Threaded Sections
• 4. 4a & 4b—Annular Grooves
• 5. High Pressure Connector
• 6. Recessed Section
• 7. Polyurethane Back-up ring
• 8. O-ring
• 9. 9a & 9b—O-rings
• 10. Elastic Sleeve
• 11. Sleeve Retainer Bushing 11a & 11b
• 12. Spacer washers 12a & 12b
• 13. Nuts 13a & 13b
• 14. Axial Passageway
• 15. Radial Passageway
• 17. Mandrel Adapter—Threaded
• 20. Mandrel Assembly Sleeve retaining bushing
• 21. Bushing Threads
• 22. Locking nut
• 23. Sleeve retaining bushing
• 24. Sleeve internal threads

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Description of the First Embodiment

Referring to FIG. 1 and FIG. 2, a mandrel assembly is made up of the following components. The components are made of appropriate high strength materials such as, but not limited to, steel, stainless steel, titanium, high strength metal alloys and plastic ceramics. An elastic sleeve, usually of a polymer, and made of polyurethane or similar materials with good machining and high elasticity properties. The choice of materials can vary based on the application and environmental requirements that the assembly may be used in it.

A mandrel shaft 1 is made up of an appropriate high strength material and is generally formed of a uniform diameter along its length where it joins with reduced diameter threaded sections 3a & 3b, and a further reduced diameter high pressure connection 5 outboard of threaded section 3b. This allows components mounted thereon to be slid off and replaced when required. Annular grooves 4a & 4b are formed in the major diameter section of the mandrel shaft 1. The mandrel shaft OD 2 between the annular grooves 4a & 4b is of a reduced OD slightly less than the major OD outboard of the grooves 4a & 4b. O-rings 9a & 9b which are made of a suitably soft material as known in the art encircle the mandrel shaft 1 and sit in the annular grooves 4a & 4b. The high pressure connection 5 is capable of joining the shaft to a variable pressure fluid supply up to 60,000 psi and has an annular recess 6 formed in it. A polyurethane backup ring 7 and O-ring 8, which is made of a suitably soft material, sits in the annular recess 6. The inner diameters of backup 7 and O-ring 8 must be slightly smaller than the annular recess 6 diameter. The outer diameter of backup 7 must be slightly smaller than the major diameter of the high pressure connector 5. The outer diameter of O-ring 8 must be slightly larger than the major diameter of the high pressure connector 5. An elastic sleeve 10 made of an appropriate material, as aforesaid, with good machining and elastic properties with an ID slightly larger than the mandrel shaft 1 major diameter allows it to slide in an axial direction on the mandrel shaft 1. The elastic sleeve 10 major OD is equal to the sleeve retainer bushings 11a & 11b OD. Sleeve retainer bushings 11a & 11b are made of an appropriate high strength material with an ID slightly larger than the OD of the mandrel shaft 1, has a major diameter to allow it to slide freely in an axial direction on the mandrel shaft 1. The mating surfaces 16a & 16b of the elastic sleeve 10 and sleeve retainer bushing 11a & 11b that overrides and join with the elastic expander 10 surfaces are an interference fit. The elastic sleeve 10 and sleeve retainer bushing 11a & 11b mating surfaces 16a & 16b can be an overlapping bevel surface, an overlapping step surface, or overlapping interlocking mating surfaces 16a as depicted in FIG. 3.

Outboard and adjacent to the sleeve retainer bushings 11a & 11b are retaining washers 12a & 12b are made of an appropriate high strength material with an ID slightly larger than the OD of the threaded sections 3a & 3b of the mandrel shaft 1, and an OD equal to the OD of the sleeve retainer bushings 11a& 11b. Outboard and adjacent to retaining washers 12a & 12b are nuts 13a & 13b that are secured in threaded engagement with threaded sections 3a & 3b of the mandrel shaft 1 and limits the axial movement of the components on the mandrel shaft 1 locking them in place. The mandrel shaft 1 has an axial oriented central bore 14 that intersects with a radially oriented bore 15 to provide a path for the pressurized fluid to reach the annular void between the mandrel shaft 1 and the elastic sleeve 10. Various configurations of high pressure adapters can be threaded onto the threaded end 3b of the mandrel to connect the mandrel shaft 1 to a high pressure fluid source.

The adapter 17, shown in FIG. 1 and FIG. 2, is shown as an example only and is not the sole means of connecting the mandrel shaft 1 to a high pressure fluid source. A high pressure flexible hose (not shown) may be attached directly to the mandrel assembly through an appropriately threaded mandrel adapter and used to supply pressurized fluid. This configuration allows for positioning the mandrel down a tube to a predetermined position from the tube end to hydroform the tube. The mandrel shaft 1 can be modified by continuing the axial passageway 14 through the mandrel shaft 1 instead of stopping it mid-shaft, and a high pressure connection 5 added to the threaded section 3a, may work appropriately at that end of the mandrel. This allows multiple mandrel assemblies of varying lengths to be interconnected end to end with interconnections of varying lengths. When activated, multiple locations can be hydroformed at similar or varying expansion lengths at the same time. The mandrel shaft 1 can include a safety vent passageway that allows the mandrel to be safely used to hydroform a hollow cylinder with a blind hole. The mandrel can be attached to a hand-held mandrel holder or a robotically controlled mandrel holder by changing the configuration of the mandrel adapter connections. An adjustable stop collar can be attached to the mandrel adapter by threads to facilitate fine adjustments in the mandrel insertion placement.

A technician would assemble the system as indicated above. The person would then insert the mandrel assembly into the material to be hydroformed. The person would actuate the power supply using either a remote operation switch on the mandrel holder handle or using a manual operation switch located on the power supply. Pressurized fluid would then be pumped from the power supply via a suitable umbilical capable of delivering the maximum rated output from the power supply's pump. The pressurized fluid will enter the mandrel via passageways 14 & 15 and enter the annular void between mandrel shaft 1 and the elastic expander 10. The pressurized fluid fills the void and exerts pressure radially on the elastic expander 10. The elastic expander 10 deforms radially exerting pressure on the metal cylinder, expanding it radially. The person would hold the switch until the indicators would indicate the hydroforming process is complete. When the hydroforming process is complete, the person would release the switch and then remove the mandrel assembly from the material.

Description of the Second Embodiment

Refer to FIG. 4. The sleeve retaining bushing 20 may have internal threads 21 to engage external threads on the locking nut 22, thereby combining the sleeve retaining bushing, retaining washer, and locking nut functions into one piece.

Description of the Third Embodiment

Refer to FIG. 5. The sleeve retaining bushing 23 used on the primary end of the mandrel (end nearest to the high pressure fluid source) may have internal threads 24 to match the threads on the mandrel shaft 1. It may have a major OD machined equal to or larger than the cylinder being expanded to facilitate precise positioning of the mandrel assembly, by indexing it off the end of the cylinder to be expanded. Thereby combining the sleeve retaining bushing, retaining washer, locking nut, and positioning collar functions into one piece.

Variations or modifications to the subject matter of this invention may occur to those skilled in the art upon review of the summary of the invention as provided herein, and upon undertaking a study of the description of its preferred embodiment, in view of the drawings. The subject matter of this invention as explained, is set forth for illustrative purposes only.

Claims

1. An apparatus for radially expanding a cylinder by hydroforming the same utilizing hydraulic pressure, comprising: a metal cylinder to be expanded;a mandrel provided for insertion into said metal cylinder in preparation for performance of the hydroforming function;an elastic sleeve provided upon the mandrel at least along a portion of its length, and said elastic sleeve arranged in contiguity with the interior of the cylinder to be hydroformed;said mandrel having an internal approximate axial pathway through which hydraulic fluids may insert during hydroforming, said mandrel having at least one approximate radial pathway extending from its axial pathway to the surface of the mandrel, and said pathways providing the means for introducing a pressurized fluid to the area between the mandrel and its elastic sleeve to expand the elastic sleeve against the interior of the cylinder being hydroformed interiorly thereof;seals provided between the elastic sleeve and the surface of the mandrel to seal in pressurized fluid during hydroforming;said mandrel at one end having an adapter to which a high pressure fluid source may connect therewith for introducing pressurized fluids into the mandrel in preparation for the performance of hydroforming process upon the associated metal cylinder.

2. The apparatus of claim 1 and including a series of O-rings provided upon said mandrel and the interior of said elastic sleeve to contain the pressurized fluids therein during performance of a hydroforming function.

3. The apparatus of claim 1, wherein said elastic sleeve slides onto said mandrel and contacts the O-rings operatively associated with said mandrel to form a hydraulic fluid pressure expansion zone between said elastic sleeve, and the exterior of said mandrel, to obtain expansion of the elastic cylinder when hydroforming a metal cylinder into an expanded shape.

4. The apparatus of claim 3, wherein said elastic sleeve extends over the substantial length of the said mandrel when assembled for a hydroforming operation.

5. The apparatus of claim 4, and including a bushing provided at each end of the elastic sleeve, and retaining washers and threaded nuts applied to each end of the mandrel to hold the said bushings in place against the ends of the elastic sleeve to assure retention of the pressurized hydraulic fluid during performance of a hydroforming operation.

6. The apparatus of claim 5, and including a back up ring provided between the end of the mandrel and within the adapter to maintain a seal of the pressurized fluid as it enters into the mandrel during performance of a hydroforming function.

7. The apparatus of claim 6, and including a further O-ring provided to form the seal between the adapter and the proximate end of the mandrel to assure fluid sealing at that position.

8. The apparatus of claim 1, wherein said elastic sleeve is formed of a polymer.

9. The apparatus of claim 8, said polymer is a polyurethane.