Flexible metal hose connector and method for forming same

Abstract: An end fitting is secured to a flexible metal hose comprised of a corrugated tube enclosed in a tubular braid in a manner that provides a single weld operation. An end of the hose is cut to bring the tube and braid ends into alignment. Thereafter, an end fitting is moved over the hose end and radially swaged into gripping engagement with the hose. A circumferential deep penetration weld integrally secures all the components, namely, the tube, the braid, and the fitting.

Description: This invention relates to a method of preparing a flexible metal hose and securing a fitting thereto, as well as to the metal hose and the fitting assembly obtained thereby. The flexible metal hose comprises an inner corrugated tube which is covered by a braid. Any one of a number of fluid fittings may be secured to an end of the flexible metal hose, and it is envisioned that opposite ends of the flexible metal hose may even incorporate different types of fittings. The assembly finds application in installing flexible loops that allow for thermal expansion, misalignment, intermittent flexing, or continuous flexure, for example as may be caused by vibration. Of course, and as will be readily understood, it may also be used for static bend arrangements. These uses and the environment are merely exemplary, and it will be appreciated that the invention may be advantageously employed in still other environments and applications. A conventional, prior art method of assembling a flexible metal hose connector incorporates two separate welding operations. As used herein the term "welding" is to be accorded its broadest interpretation and encompasses various types of welding as well as the concepts of brazing and soldering. An alternate expression for welding is fusion bonding and these terms will generally be used synonymously. According to one prior art method of assembling flexible metal hose, the corrugated tube and the braided sheath are terminated at a desired location. A sleeve is then advanced over the metal braid and aligned with the terminal ends of the tube and braid. A first weld, known as a cap weld, joins the sleeve, braid, and tube together. Thereafter, a fitting is advanced into abutting engagement with the first weld area, and a second weld, particularly a fillet weld, joins the external periphery of the fitting to the terminal end of the metal hose, i.e., the welded sleeve, braid, and tube. Although this method of assembly has been used with a tremendous amount of commercial success, a primary drawback is that it relies on the skill of the individual welder. Variations may occur from one metal hose connector to another, whether assembled by the same or different welders. For example, the welder secures the tube, braid, and sleeve together in the first weld step. These three components may not be concentrically secured together, or one of the components may not be effectively secured to the other two components. The welder must also provide a generally planar surface to adapt the intermediate assembly to receipt of the fitting. Again, such steps are labor intensive and subject to variation from one completed flexible metal hose connector to another. A number of other methods have been proposed in prior art patents. These include U.S. Patent Nos. 2,172,532 - Fentress; 2,473,879 - Guarnaschelli; 4,527,819 - Desilets, et al.; 3,740,832 - Toepper; 2,028,600-Guarnaschelli; 2,444,988 - Guarnaschelli; and 2,300,547-Guarnaschelli. FR-A-2590349 discloses the preambles of claims 1 and 5. In US-A-3023496, a single weld is used to weld together a two-part fitting and to weld a shoulder of the fitting to an end face of an axially-crushed end of a hose. FR-A-1144381 discloses a penetration weld. According to a first aspect of the present invention, there is provided a method of securing a one-piece metal fitting to an end of a flexible cylindrical metal hose wherein the flexible metal hose includes a corrugated tube with a braid received over the tube, and the metal fitting includes a generally cylindrical first body section having a first end and a second end with a cylindrical bore sized to closely receive the end of the flexible metal hose and extending axially inwardly from the first end toward the second end to define a continuous cylindrical side wall terminating in a radially inwardly extending shoulder, the method comprising the steps of: a) cutting the end of the hose to terminate the corrugated tube and the braid perpendicular to the axis of the hose; b) inserting the cut end of the hose into the cylindrical bore of the fitting to bring the cut end into engagement with the shoulder, and c) deforming the first body section radially inward to mechanically interlock the braid, tube and fitting together, characterised in that the side wall of the first body section is of a relatively uniform first thickness from the first end to a first point spaced a short distance from the shoulder and a substantially thinner second thickness from the first point to the shoulder, and in that the method further comprises the step of: d) welding with a deep penetration weld in a continuous circumferential path the fitting to the braid and tube in the area of the thinner second thickness of the first body section from the first point to the shoulder. According to a second aspect of the present invention, there is provided a flexible metal hose and end fitting assembly comprising: a hose including a hollow tube having a longitudinal axis defined by corrugations substantially equally spaced apart in an axial direction with a braid received over the tube, the braid and the tube terminating perpendicular to the longitudinal axis of the tube and defining an end of the hose; and a one-piece metal end fitting comprising a cylindrical first body section having a cylindrical bore extending axially thereinto and closely receiving the end of the hose, the bore terminating in a radially inwardly extending shoulder which engages the end of the hose; the first body section of the fitting being deformed radially inward to mechanically grip the hose; characterised in that: a groove extends circumferentially about the first body section and along the bottom of the groove is a deep penetration weld which is adjacent the shoulder and welds the fitting to the end of the hose such that the ends of the tube and braid of the hose are located inwardly beyond the weld; and the radial inward deformation of the first body section is on the side of the weld axially opposite the shoulder. A non-limiting embodiment of the present invention will now be described with reference to the accompanying drawings, in which:- FIGURE 1 is a cross-sectional view through an end fitting and a hose end to which it is to be connected; FIGURE 2 is a cross-sectional view through the fitting and hose end of FIGURE 1 showing the hose end being inserted into the fitting; FIGURE 3 is a cross-sectional view through the fitting and hose end showing the fitting body being swaged into gripping engagement with the hose end; FIGURE 4 is a view taken on line 18-18 of FIGURE 3; FIGURE 5 is a cross-sectional view showing the fitting after the crimping operation and preparatory to the welding operation; and FIGURE 6 is a cross-sectional view through the hose end and fitting after completion of the welding operation. The FIGURES show a flexible metal hose A' to which is secured a fitting 90. More particularly, and with reference to FIGURES 1 and 2, the flexible metal hose A' comprises an inner corrugated tube 10' and a surrounding sheath or metal braid 12'. As shown, the corrugated tubing is defined by a series of concentric corrugations, although it will be understood that in other applications helical corrugations may be used with equal success. Generally, the corrugations are equally spaced apart in the longitudinal direction whether helical or concentric corrugations are used. Further, according to a preferred arrangement, the hose is a type 316 stainless steel, while the braid is a type 321 stainless steel. As will be readily understood by one skilled in the art, these materials are exemplary only since still other materials may be suitable for different purposes. Ends 14', 16' of the tube and braid, respectively, are terminated in any well known manner. The fitting 90 is a one-piece, machined end fitting component preferably formed from stainless steel and having a somewhat cylindrical main body section 92 and a reduced diameter cylindrical tube adapter end portion 94. This end portion could, however, be any desired type of end or fitting body. At the right-hand end of the main body 92, there is a cylindrical bore 96 which has a diameter d that is only slightly greater than the outer diameter of the braided flexible metal hose A'. The diameter d is selected so as to allow the hose A' to be closely and snugly received therein during the subsequent assembly steps. The bore 96 terminates in a radially inward extending shoulder portion 98. A transition section 100 joins the bore 96 with the reduced diameter outlet bore 102 formed centrally of the outlet end portion 94. The inlet end to the bore 96 is preferably provided with a peripheral chamfer 104 that removes burrs and can assist in the installation of the braided flexible metal hose into position. A radially extending flange portion 106 acts to reinforce the inlet end of bore 96 and serves to provide a holding and locating means for subsequent operations. The side wall surrounding the bore 96 has a first thickness T and a reduced second thickness T 1 that produces a groove 93 adjacent the area of the shoulder 98. The purpose for this thinner grooved section will subsequently be described in some detail and explained with reference to the practice of the method used for joining the end fitting 90 to the flexible metal hose A'. The portion to the left of groove 93 and shoulder portion 98 (as viewed in FIGURES 1 and 2) are relatively heavy and thick. In accordance with the subject method, the first step is to cut the braided flexible metal hose A' to its desired length. In making the cut, it is not necessary to cut through the corrugated tubing at any particular location. The hose, including the braid and the corrugated tubing, can be cut at a crest, root, or flank of a convolution of the corrugated tubing 10'. The cut should be performed, however, in such a way as to leave the end of the braid covering 12' clean and without a frayed end. This can be easily accomplished with friction cutoff blades that are in general use in industry for cutting metal tubing and the like. It is desirable, but not absolutely necessary, for the ends of the tube and braid to terminate generally in the same plane. After the end of the hose A' is cut to bring the braid and inner corrugated tube 10' into general alignment, the end portion is slipped into the counterbore 96 of the end fitting to bring the end of the hose A' into engagement with the inner shoulder 98. FIGURE 2 shows the hose A' in its desired located position within the end fitting 90. Preferably, a tool such as the two-part assembly ring 110 is used to facilitate the installation of the hose A' into located position within the end fitting 90. The assembly ring 110 comprises two half ring elements 110a and 110b that are shaped so as to provide a conical entrance mouth 112 leading to a circular gripping portion 114. Note that the gripping portion 114 is contoured so as to tightly engage and hold the fitting 90 in alignment with the conical guide mouth 112. The two halves 110a and 110b are, of course, suitably mounted so as to be movable in a radial gripping direction toward the fitting 90 and suitably held therein during the tubing installation process. After the flexible metal hose A' is firmly seated in the end fitting 90, the end fitting is crimped radially inward circumferentially about the larger diameter end portion circumferentially thereabout in the area adjacent the groove at the transition between the thick and thin walled portions. The crimping or radial inward swaging is preferably carried out in the manner best understood by reference to FIGURES 3 and 4. As shown therein, a support stop element 115 is provided with a central opening 116 sized to closely receive the smaller diameter end portion 94 of the fitting 90. A suitable conically shaped mouth 118 is arranged to engage the tapered transition wall 90a of fitting 90. This functions in conjunction with assembly ring 110 and serves as a stop and additional support for the tube and fitting end during the crimping operation. Preferably, the crimping or swaging is accomplished through the use of eight radially movable crimping fingers formed, for example, from tool steel and having the end face configuration best shown in FIGURE 3. Preferably, there are eight of the crimp fingers positioned and shaped generally as shown in FIGURE 4. They are movable radial between the radially closed position shown in FIGURE 4 and a radial outward or open position which is shown in FIGURE 3. Inward movement of the crimp fingers 120 is accomplished through any suitable manual or power actuated means having sufficient power to compress the circumferential wall of the large diameter end of fitting 90 to the general shape shown in FIGURE 5. This causes the wall to be deformed to the shape shown and to move inwardly and firmly and tightly grip the flexible metal hose A' and assure good contact between the inner wall of the bore 96 and the flexible metal hose A'. Additionally, the braided portion 12' firmly engages the corrugated inner tube 10'. Thereafter, the juncture between the tube and the fitting is deep penetration welded totally circumferentially about the end at the location shown above the thin walled and grooved portion 93 of the sleeve adjacent the end wall 98 . If the weld is properly made to the desired penetration, the penetration joins the tube, the braid, and the end fitting together in a leak-tight manner. The deep penetration makes the weld more independent of the phase or pitch of the convoluted hose. The resulting welded fitting is as shown in FIGURE 6. The geometry of the fitting 90 is important and produces an improved function and appearance of the resulting product. In particular, the thin wall area at the bottom of groove 93 allows easier deep penetration of the weld. The thicker walls on both sides of the groove act as heat sinks. These confine the weld puddle edge in a way that keeps the puddle under control and prevents undesired dripping and movement of the molten material. This results in improvement of the weld in terms of strength and uniformity, as well as in terms of appearance. Note that, as shown in FIGURE 6, the welded area generally assumes a smoothly contoured groove configuration. In addition to the above, it should be noted that the relationship between the end wall or shoulder 98 and the groove 93 assures that the ends of the tube and braid of the flexible metal hose A' are located inwardly beyond the point where the weld is applied. This prevents the braid from being omitted from the weld. The consistent braid inclusion is an improvement relative to prior techniques. The cap weld arrangement of prior art arrangements is eliminated and only the single weld is required to join the fitting to the hose. Thus, in the final product, the braid, tube and fitting become integrally joined in the welding operation. Although the process has been described as an autogenous weld, i.e., not requiring a filler wire or material for the fusion bonding, it will be understood by those skilled in the art that a filler wire may be used. The above-described process results in a flexible metal hose with an integral fitting in which all components of the assembly are joined together by a single weld. The described method substantially reduces the time required to join a fitting to a flexible metal hose and overcomes much of the variability encountered with prior art methods. The permanent welded connection avoids problems associated with corrosive fluids, shock from pressure surges, temperature cycling, and system vibration.

Claims: A method of securing a one-piece metal fitting (90) to an end of a flexible cylindrical metal hose (A') wherein the flexible metal hose includes a corrugated tube (10') with a braid (12') received over the tube, and the metal fitting (90) includes a generally cylindrical first body section (92) having a first end and a second end with a cylindrical bore (96) sized to closely receive the end of the flexible metal hose (A') and extending axially inwardly from the first end toward the second end to define a continuous cylindrical side wall terminating in a radially inwardly extending shoulder (98), the method comprising the steps of: a) cutting the end of the hose (A') to terminate the corrugated tube (10') and the braid (12') perpendicular to the axis of the hose; b) inserting the cut end of the hose (A') into the cylindrical bore (96) of the fitting (90) to bring the cut end into engagement with the shoulder (98); and c) deforming the first body section (92) radially inward to mechanically interlock the braid (12'), tube (10') and fitting (90) together; characterised in that the side wall of the first body section (92) is of a relatively uniform first thickness (T) from the first end to a first point spaced a short distance from the shoulder (98) and a substantially thinner second thickness (T 1 ) from the first point to the shoulder (98), and in that the method further comprises the step of: d) welding with a deep penetration weld in a continuous circumferential path the fitting (90) to the braid (12') and tube (10') in the area of the thinner second thickness (T 1 ) of the first body section (92) from the first point to the shoulder (98). The method as set forth in claim 1 wherein the step of deforming the first body section (92) comprises swaging the first body section radially inward uniformly about the outer circumference. The method as set forth in claim 1 or 2 wherein the cylindrical bore (96) is of uniform diameter (d) and the substantially thinner second thickness (T 1 ) of the first body section (92) is the result of a reduction of the outer diameter of the first body section in the area of the shoulder (98). The method as set forth in any one of claims I to 3 wherein the cutting step comprises cutting the end of the hose (A') to terminate the corrugated tube (10') and the braid (12') in substantially the same plane perpendicular to the axis of the hose. A flexible metal hose and end fitting assembly comprising: a hose (A') including a hollow tube (10') having a longitudinal axis defined by corrugations substantially equally spaced apart in an axial direction with a braid (12') received over the tube, the braid and the tube terminating perpendicular to the longitudinal axis of the tube and defining an end of the hose; and a one-piece metal end fitting (90) comprising a cylindrical first body section (92) having a cylindrical bore (96) extending axially thereinto and closely receiving the end of the hose (A'), the bore terminating in a radially inwardly extending shoulder (98) which engages the end of the hose; the first body section (92) of the fitting (90) being deformed radially inward to mechanically grip the hose (A'); characterised in that: a groove (93) extends circumferentially about the first body section (92) and along the bottom of the groove is a deep penetration weld which is adjacent the shoulder (98) and welds the fitting (90) to the end of the hose (A') such that the ends of the tube (10') and braid (12') of the hose (A') are located inwardly beyond the weld; and the radial inward deformation of the first body section (92) is on the side of the weld axially opposite the shoulder (98).

Inventors: KRECZKO GREGORY, ZABORSZKI STEPHEN J, KRECZKO, GREGORY, ZABORSZKI, STEPHEN J.
Applicants: SWAGELOK QUICK CONNECT CO, SWAGELOK QUICK-CONNECT CO.
Application year: 1995
Main classification: F16L33
IPC codes: F16L33, F16L13, F16L11, F16L21