TUBING CONNECTOR, METHOD OF MANUFACTURE, AND METHOD OF ASSEMBLY

Related Application

The present application claims the benefit of U.S. Provisional Application No. 60/917,880 filed May 14, 2007, which is incorporated herein in its entirety by reference.

Field of the Invention

This invention relates to couplings for plastic tubing, more particularly the application relates to couplings for handling ultra pure fluids used, for example, in the semiconductor processing industry, methods of manufacturing such couplings, and methods of assembly of such couplings.

Backfiround of the Invention

Numerous industries use tubing and fittings of fluoropolymers, e.g., perfluoroalkoxy (PFA), polytetrafluoroethylene (PTFE), and other synthetic resins, for the transfer of various fluids in extreme temperatures and conditions. These fluoropolymer fittings offer extraordinary corrosion resistance and high purity which make the materials ideal for the semiconductor processing industry. However, such plastic fittings and tubings, in that they are made of plastic rather than traditional materials such as stainless steel, bronze and copper, do not have the rigidity and strength of conventional fittings. Thus particular connection configurations that may work very well with metal fittings and metal tubing, do not work adequately when made from polymer and particularly fluoropolymer materials. To maintain a clean and non-hazardous process it is essential that the fittings provided for coupling sections of tubing are not easily disconnected and that the integrity of tubing/fitting interface is maintained. Various types of fluoropolymer fittings have been provided for these purposes.

One standard type of fitting known as FLARETEK® fitting, available from the assignee of this application, provides for a fitting body, having a nose with a rounded tip and cylindrical section, and a threaded portion at the base of the nose. A fitting nut is typically placed on the tubing before the tubing end is flared. The end portion of tubing with the flared end is placed over the nose section and the fitting nut is slid over and secured to the fitting body axially compressing the flared end on the nose by the collar of the nut creating a seal between the inside surface of the tubing and nose. When assembled

the nut extends completely over the flared section. The seal is created around the substantially cylindrical nose but is principally at the tip of the nose. In these fittings, the inside diameter of the flared section is slightly greater that the outside diameter of the non- flared portion of the tubing. The tubing flare forms an exaggerated s-shape with the flared section axially extending and having a constant diameter. The flare is formed by heating the end of the tubing and expanding same on an appropriately shaped form.

Such flared fitting bodies have the nose portion including the portions which seal exposed when they are unassembled subjecting the fitting bodies to potential damage. Similarly, the exterior threads are also exposed subjecting them to possible damage. However in certain applications it would be desirable to have a flared fitting that offers further advantages such as additional secondary sealing, a fitting in which the sealing surfaces of fitting body are not exposed when the fitting is unassembled, and moreover that provides more protection to the sealing components when assembled.

Another coupling that has gained acceptance in these applications is reflected in U.S. Patent Nos. 5,154,453 and 5,743,572. These fittings are known as Pillar fittings and utilize a very high tolerenced ring insert that is inserted and retained into a tubing end. The insert forces the tubing into a bulbous shape on the exterior and has a cylindrical bore on the interior of the insert. The bulbous shape provides an excellent shape for sealing with a fitting but requires a permanently placed insert to maintain the bulbous shape. The deformed tubing end with the insert is engaged into another highly tolerenced fitting body and is secured thereto with a nut that engages with threading on the exterior of the fitting body. The nut provides axial force to the bulbous shape opposite the tip of the tubing end to seal the tubing end and insert to the fitting body. Although these fittings provide a coupling of high integrity, particularly provided by the bulbous exterior of the tubing, they are difficult to manufacture to the exacting tolerances needed.

Summary of the Invention

A coupling utilizes a polymer tubing end portion with an expanded end, such as a bulbous shape on the exterior and a corresponding interior bulbous shape, the tubing end portion engages with a fitting body with a bulbous exterior surface and an annular slot adjacent to the bulbous exterior surface, the tubing end portion and fitting are coupled together with a nut that pulls the tubing end portion and fitting body together. The slot has

opposing annular surfaces, in preferred embodiments, the slot has a converging portion where both surfaces are parallel with respect to one another and converge radially inward.

In a preferred embodiment of the invention, the polymer is resilient and has a memory such that the bulbous shape at the tubing end portion may be formed by inserting and withdrawing a bulbous mandrel into the tubing end to be joined. The bulbous shape has a maximum radius away from the tip of the tubing end portion. The operation of insertion and withdrawal of the mandrel can conveniently be accomplished at room temperature. Preferably the mandrel is inserted by first securing a gripping ring assembly to the exterior of the tubing distally position from where the bulbous portion will be formed opposite the tip of the tubing end portion, and utilizing the gripping ring assembly to secure the tubing while the mandrel is being inserted and remove to preform the bulbous shape. Preferably the gripping ring assembly is permanently attached and also provides a engagement member for a nut when the tubing end portion is attached to the fitting body. The gripping ring assembly may have a gripping ring with plurality of axially extending fingers, spaced circumferentially, with gripping teeth at the ends of the fingers. A second locking ring portion slides radially onto the gripping ring with a wedge action to press the gripping teeth into the exterior of the tubing. The gripping ring assembly may have an exterior facing cam wedge surface to allow the nut to slide over the assembled gripping ring assembly and be retained thereon.

In a preferred embodiment, a connection is made by radially expanding a tubular end portion, with the radial expansion extending axially over an axial distance of at least 2 times the original radii of the tubing. In a preferred embodiment from the tip of the end portion, after the radial expansion, the radius of the tubing portion increases initially from the tip with the measured radii moving away from the tip and then decreases to the original tubing radius. In a particular embodiment, the expansion is performed at room temperature, or at a temperature from 60 degrees Fahrenheit to 90 degrees Fahrenheit.

In a particular embodiment the tubing end portion is radially expanded by a mandrel that the mandrel having an insertion head with a tip having a tapered portion, and a cylindrical portion or a bulbous portion with a radial dimension greater than the inside dimension of the tubing. The mandrel may be fully inserted during the expansion so that the decreasing radius portion of the mandrel is at least at the tip of the tubing end portion.

In a preferred embodiment, the fitting body has an exterior threaded portion, a bulbous shaped male portion, partially covered by the threaded portion, the bulbous portion and threaded portion defining an annular slot that converges inwardly and is sized to sealingly receive the tubing end with the preformed bulbous shape. The method also includes a technique to manufacture the undercut portion of the annular slot that converges radially inward.

In certain embodiments, the fitting body may be formed of two portions, an inner body portion and an outer body portion. The inner portion having a fluid flow bore and surface, the bulbous exterior surface and the inner surface that faces outwardly of the two surfaces of the annular groove. The outer portion having the outer surface that faces inwardly, and in a preferred embodiment, a threaded

An advantage of the invention is that manufacturing tolerences are not as strict as with other bulbous connectors. Moreover, fewer leakpaths are presented than in other connectors that use bulbous connections.

An aspect of the invention is that the bulbous shape can surprisingly be formed in desireable polymers, such as perfluoroalkosy (PFA) by the simple insertion and withdrawal of a mandrel that has a bulbous shape slightly larger than the remaining bulbous shape. The maximum diameter portion of the mandrel is inserted past the tip a desired distance and is then withdrawn. The memory of the PFA retains a reduced shadow version of the bulbous shape of the mandrel and significantly has the tip at a lesser diameter than maximum diameter of the bulbous shape. Without inside support of the bulbous shape, over a period of a plurality of hours the bulbous shape will fade and return to the original or near original shape of the tubing end portion. The connection between the bulbous shaped tubing end portion and the cooperating fitting is accomplished typically momentarily, that is a few minutes, after making the bulbous shape so the return to the original shape is not an issue. This delayed resiliency, or memory of the original tubular shape, is a positive feature in that it serves to maintain the seal between the inside surface of the bulbous portion of the tubing end portion and the outside sealing surface of the fitting body portion.

A further advantage is that the bulbous shape of the tubing end can be formed manually with simple tools. A further advantage is that the undercut portion of the fitting

can unexpectedly be injected molded and with minimal moving parts (mold inserts) in the mold.

An aspect of the invention is a method of making a connection between a PFA polymer tubing end portion and a polymer fitting by cold forming the end portion utilizing a mandrel to conform to a annular recess in the polymer fitting.

An aspect of the invention herein is a method of making a fluid flow connection as described and illustrated herein.

Aspects of the invention herein include the individual components and the method of forming or manufacturing same. Specifically the bulbous tubing end portion and the fitting with the bulbous exterior sealing surface and annular slot which may be converging. The fitting may be formed by injection molding or machined from two pieces if PTFE is utilized.

An aspect of the invention herein is a fluid flow valves, sensors, filter bodies, manifolds, flow controllers with a component of the connection described and illustrated herein.

An aspect of the invention herein are the tools to accomplish the manufacture and/or assembly of the components and/or connector described and illustrated herein, as well as a kit comprising same.

Description of the Figures

Figure 1 is a cross-sectional view of a coupling according to embodiments of the invention herein.

Figure 2 is a perspective view of a tubing portion with the bulbous portion, and gripping ring assembly, and nut thereon ready and a cooperating fitting body integral with a generalized fluid flow component body according to embodiments of the invention.

Figure 3 is a cross-section of a fitting body, tubing end portion ready for coupling according to embodiments of the invention.

Figure 4 is a perspective view of a locking ring assembly according to embodiments of the inventions.

Figure 5 is a perspective view of a nut on a tubing end portion prior to forming the bulbous portion.

Figure 6 is a cross sectional view of another embodiment of a coupling.

Figures 7 through 10 illustrate the technique of forming the bulbous shape in the tubing end portion in cross section.

Figures 11 through 13 are views of a manually operated tool suitable for installing the gripping ring assembly on the tubing portion and suitable for inserting and removing the mandrel according to embodiments of the invention, illustrated with the connector components.

Detailed Description of the Invention

Referring to Figures 1, 2, and 3, the principal components of the coupling 12 or connector are illustrated. Tubing 18 having a tubing end portion 20 has a continual wall 21 with a bulging or bulbous portion 22 having a bulbous exterior surface 24, a bulbous interior surface 26, a tip 28 with an opening 29, and a non-deformed or uniform radius portion 30. The tip has an inside diameter dl and radius rl . The tubing has an inside radius r2 which is also the inside radius of the uniform radius portion. The inside radius of the bulbous portion increases as the distance from the tip increases to the point of maximum radius as illustrated by radius r3. The inside radius of the bulbous portion then decreases to the tubing radius r2 or may go slightly lower that the tubing radius due to the gripping ring assembly discussed below.

Said tubing end portion 20 is engageable or engaged in the various views with a fitting body portion 32. The fitting body portion 32 may be integral with a fluid flow component body portion 34, such as a valve body, a manifold, a flow controller, a filter body, a tee, a sensor body, or other components. The fitting body portion 32 has a nose 35 with a outside or external radius r4, a bulging or bulbous portion 36 with an externally facing sealing surface configured as an exterior facing bulbous surface 38 having an outside radius r5. A substantially cylindrical bore 40 with an axis α constituting a fluid flow passageway extends through the fitting body portion 32. The bore will preferably have a radius r6 equal to the tubing radius r2. The fitting body portion has an annular slot 42 for receiving and sealing with the tubing end portion tip 28. The slot has an outwardly facing surface 43, an inwardly facing surface 44, and a slot bottom 45, all of which can provide sealing engagement with corresponding surfaces of the tubing end portion to

effectuate the seal of the coupling to prevent leakage of the coupling. The exterior facing bulbous surface 38 is contiguous and coextensive with the outwardly facing surface of the annular slot.

Referring to Figures 1 , 3, and 4, a gripping ring assembly 52 secured on the tubing portion has a gripping ring 54 with axially extending and radially flexing gripping claws 55, separated by gaps 56, and a wedge locking ring 58 that cooperates with the gripping ring. The gripping ring also may have a locator tab 56 that mates with an aperture 57 on the locking ring. Wedge shaped locking tabs 59 on the gripping ring may be provided to lock the assembly together on the exterior surface of the tubing.

Referring to the figures, a nut 60 with inwardly facing threads 62 engages the exterior threads 70 of the fitting body. The nut has a stop surface 74 which engages a flange 76 on the body portion. Also wedge or cam portions 61 may extend from the locking ring or alternatively the gripping ring to provide a locking action with the nut 60 to retain or fix the axial position of the nut on the tubing end portion where the gripping ring assembly is secured. Moreover, the axial fixation of the nut on the tubing end portion allows the unscrewing of the nut from the fitting portion to pull the bulbous portion of the tubing end portion off of the bulbous portion of the fitting portion. A pusher portion 80 of the nut engages the gripping ring assembly 52 and thereby the tubing end portion. Flats 82 may be provided to aid in screwing the nut onto the fitting.

Figures 2 and 3 illustrate the coupling ready to be assembly into a connection of high integrity. Figure 1 is the "made" high integrity connection. Note the nut 60 freely rotates on the tubing end portion 20. The bulbous portion 22 of the tubing portion confronts and contacts the nose of the fitting body, at which contact point the nut 60 may be threadingly engaged with the exterior threads of the fitting body portion. Rotation of the nut then urges the bulbous portion of the tubing end portion forward (toward the fitting body) by way of axial contact with the gripping ring assembly such that the bulbous portion 22 of the tubing portion slides over and sealingly engages with the bulbous portion 36 of the fitting body and said tubing end portion is sealingly engaged in the slot 142 of the fitting body.

Significantly, in preferred embodiments, the inside radius rl of the tip 28 of the tubing end portion is greater that the outside radius of the nose of the fitting body portion 32 allowing easy guiding and orientation of the tubing portion to facilitate the engagement

of the tubing portion around the fitting body portion bulbous portion. Note that in certain embodiments, the outside radius r4 of the bulbous portion of the fitting body portion is greater that the inside radius rl of the tip 28. This necessitates some expansion of the opening of the tip when the components are engaged together. Also preferably, the inside radius of the inside bulbous surface r3 is less that the outside radius r5 of the bulbous portion of the fitting body portion which facilitates a secure sealing engagement between the respective surfaces, that is, the inside bulbous surface of the tubing end portion and the outside bulbous surface of the bulbous portion of the fitting body portion.

The fitting body 32 has the bulbous end and an opposite connecting end 110 that may be attached to other fluid components integrally or by way of conventional connections or by way of another connection as described herein. Said fitting body may be an integral part of a valve or a fluid flow measurement device or connection such as a tee or elbow. The fitting body has a threaded portion 132 which in conjunction with the bulbous portion 36 defines the inwardly converging slot 142. Said slot is sized for receiving the tip and a portion of the bulbous portion of the tubing end portion.

Referring to Figure 6, an alternative embodiment is illustrated in which the fitting body portion 210 is comprised of an inner portion 214 and an outer portion 216 that are threadingly coupled together and sealingly coupled at a dovetail connection 220. The inner portion and outer portion define the annular slot 222. Such a slot is very difficult to machine and where the fluid flow component body 230 is made of PTFE, which can't be conventionally molded, and is integral with the fitting body portion, the two portions allow this coupling configuration to be utilized. This figure also illustrates a correct coupling indicator ring 240, that may provide an audible or visual indication that the nut is sufficiently or properly tightened on the fitting body portion. The indicator ring 240 is received in a first circumferential groove 244 before assembly and when the nut is tightened on the fitting body portion the indicator ring abuts against a stop surface 248 of the fitting body portion and as the nut is further tightened, that is moved axially, the indicator ring is pushed and eventually "pops" audibly to the second circumferential groove 250. Coloration such as red stripes in the grooves may be added to facilitate visual indication of the sufficiency of lack thereof of the connection.

Figures 1 1, 12, 13 illustrates a suitable hand operated tool 300 which can be utilized for locking the securement ring to the gripping ring at a suitable position on the tubing end portion. The tubing end portion be secured axially with the U-shaped bracket

308. A mandrel 310 is illustrated which is internal in the cylinder 314 and is tightened by way of the manual nut 218 in order to create the bulbous end portion. The mandrel may then be backed out with same rotatable handle.

The mandrel inserted in a tubing end portion is illustrated in Figure 8. After removal of the mandrel, the tubing end portion retains the bulbous shape as illustrated in Figure 2. Surprisingly, the bulbous shape converges towards the end face 220 of the tubing end portion. A component is principally made of fluid polymers such as PFA or PTFE. The gripping ring may be made of a more rigid polymer such as PEEK (polyetheretherketone).

Referring to Figures 1-3 and 7-10, detailed steps in making and assembling a coupling in accord herewith are as follows: First the nut 60 is slid on an deformed tubing end portion 20 to be joined. Next, the gripping assembly 52 is suitably positioned on the tubing end portion intermediate the tubing end face and the nut. The locking ring 58 is secured over the gripping ring 54 to lock the gripping ring assembly into place on the exterior of the tubing end portion. A manual or automatic tool may be is utilized for this connection by providing the positioning and clamping. Such a manual hand tool or automatic tool may then be utilized to insert the mandrel 210 into the tubing end portion and then retracting same immediately to form the bulbous portion utilizing the gripping assembly to provide an axial support while the mandrel is inserted and withdrawn. Said operation may preferably be done at room temperature. The mandrel inserted in a tubing end portion is illustrated in Figure 8. After removal of the mandrel, the tubing end portion retains the bulbous shape as illustrated in Figures 10 and 2. Surprisingly, the bulbous shape converges towards the end face 220 of the tubing end portion. A component is principally made of fluid polymers such as PFA or PTFE. The gripping ring may be made of a more rigid polymer such as PEEK (polyetheretherketone).

The fitting body 32 may already be secured to a fluid flow component or fluid flow plumbing or may now be appropriately secured such as by a welding connection. The tubing end portion then is confronted with the bulbous portion of the fitting body and the nut 60 is engaged with the threads of the fitting body. Rotation of the nut onto the threaded body preferably until said nut engages the flange 76 of the fitting body moves the bulbous portion of the tubing end portion over the bulbous portion of the fitting body, expanding the opening at the tip, and sealingly engages the bulbous portion of the tubing end portion onto the bulbous portion of the fitting body portion and into the converging annular slot.

In certain embodiments, the tubing may be heated during the processing, such as before the mandrel is inserted or after the mandrel is inserted. Where the heating is done with the mandrel inserted as shown in Figure 9, the tubing may be allowed to cool before withdrawing the mandrel to better retain the bulbous shape.

Note that the fitting body may be injection molded with a central bore mold insert and a secondary removable molding insert shaped to the converging slot or recess 142. After the molten plastic is injected into the mold and allowed to cure the central bore insert may be removed which allows the secondary insert mold insert for the converging recess or slot to then be removed causing radial inward temporary flexing of the bulbous portion of the fitting body without significantly deforming said bulbous portion of the fitting body.

The present invention may be embodied in other specific forms without departing from the spirit of the essential attributes thereof; therefore, the illustrated embodiments should be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.