Method of attaching an end of a hose and hose coupling

Abstract: A ferrule (10) for attaching a hose end portion (38) to a male-stem (32), the ferrule (10) having a tubular socket portion (12) that retains a bendable sleevelike insert (14,60) having substantially a C-shape when viewed in cross-section. Oppositely facing circumjacent edges (28,30,62,64) of the C-shaped insert (14,60) may have teeth (66) as a means for interdigitating with each other when the ferrule (60) is used to couple hose (38).

Description: The invention relates to attachable couplings of the male-stem, ferrule type for use with reinforced, flexible hose but more particularly, the invention relates to a ferrule with an insert for gripping a hose end. Couplings of the type that are post assembled to an end of a finished hose product typically have a male-stem portion that is insertable into a hose end and a ferrule that is concentric with the male-stem. Together, the male-stem and ferrule define an annular cavity for receiving a hose end. A coupling is retained by pinching the hose end in the annular cavity between the ferrule and stem such as by either radially reducing some part or element of the ferrule or by radially increasing the size of the male-stem. Some couplings are of the reusable type and use a mechanical means of the coupling such as threaded members that activate means for pinching a hose against a stem. An example of such a reusable coupling appears in European Patent 0 241 656 where a plurality of coaxial rings having alternating frustoconical surfaces are axially pressed together by a threaded member to wedge alternate rings radially inwardly. The so wedged rings pinch a hose against a stem. Such reusable couplings are usually expensive because the co-acting parts forming the coupling are typically machined from the barstock. Furthermore, the amount of pinching cannot be precisely controlled for a range of hoses when the coupling is attached to a hose. Crushable types of ferrules that may be of different sizes for different hose constructions having the same bore size are preferred for accurately controlling how an end of a hose is pinched. The present invention is directed to radially reducing the size of the ferrule by crushing it to a smaller diameter as by crimping using a plurality of closely arranged die fingers. Oftentimes, a serrated stem with a ferrule locking collar is used for high pressure hoses that are subjected to pressure impulses. For convenience of assembly, a ferrule may be pre-attached to a stem such as by crimping an end portion of the ferrule to the ferrule locking collar. While preattachment of a ferrule to a stem has advantages associated with reducing the number of parts for assembly to a hose, it introduces a disadvantage as to the number of parts required for a line of hose sizes because some hoses require the same size stem but different size ferrules. For example, three different size ferrules may be used with the same size stem for coupling a 1.27 cm (.5 in.) ID hose having different tube, reinforcement, and cover combinations. Consequently, some manufacturers prefer to select an appropriate ferrule for a hose when it is to be crimped on a hose so as to minimize inventory. In GB-A-2199100 a radially crushable type hose end fitting is disclosed. Such hose end fittings have been known for many years but that disclosed in this specification has an external sleeve made up of an outer shell member and a number of internal tubular inner members Each of these members is tubular and each is provided with a flange of the same diameter as the external diameter of the end portion of the tube. Because of the construction of the inner tubular members, there can be no question of this radially swageable product being used for a range of tubes having the same internal diameter but different external diameters. In accordance with one aspect of the invention, we provide a method of attaching an end of a hose of any one of a range of hoses having the same inside diameter but different external diameters to a hose coupling having a serrated stem comprising the steps of: (a) locating a ferrule, which has a tubular socket portion (12) with an insert having a C-shaped cross-section located therein and which insert has an internal diameter greater than the external diameter of the end of the hose with the largest external diameter in the range of hoses, over the serrated stem of the hose end coupling, (b) inserting the serrated stem into the end of the selected hose, so that the insert, which has hose gripping means on its internal face, and which has edges with square cut teeth, the teeth on one edge being longitudinally offset with respect to the teeth on the other edge, so that the insert generally surrounds the end of the hose, and (c) deforming the insert into locking engagement with the hose end so as clampingly to engage the hose end with the serrated stem, characterised in that: (d) deformation of the insert into locking engagement with the hose end is achieved by radially crushing the ferrule into engagement with the insert throughout its length to cause substantially uniform bending of the insert throughout its length to a desired diameter, whereby said hose gripping means are moved into gripping engagement with the outer surface of the end of the hose throughout the length of the insert, and the teeth are moved together and at least partially interdigitate with each other, and the hose end is deformed to be gripped by the gripping means and to grip the serrated stem throughout the length of the insert. In accordance with another aspect of the invention, we provide a hose coupling comprising a tubular member having a first end for connection to a fitting and a serrated male stem at a second end thereof for location within an end of a hose which can be selected from a range of hoses each having the same internal diameter but all having different external diameters, a ferrule having a tubular socket portion with an internal diameter adapted to receive an end of the hose, and a radially crushable sleeve-like insert of generally circular cross-section for retention in the socket portion and having a length generally corresponding to that of the socket portion and having an external diameter such that it fits within said socket portion, there being hose gripping means on the inner surface of the insert, characterised in that the insert is of C-shape and has square cut teeth on opposed longitudinal edges thereof, the teeth on one edge being longitudinally offset with respect to the teeth on the other edge of the insert, and in that the socket portion of the ferrule is radially crushable to a desired diameter and into crimping engagement with the hose end over the whole length of the insert, so that the teeth move together and the teeth on one edge at least partially interdigitate with the teeth on the other edge and so that the hose gripping means deform the out surface of the hose end portion and the inner surface of the hose end portion is caused to be deformed into gripping engagement with the serrated stem, regardless of the external diameter of the hose end portion. The socket portion of the ferrule may be made by die casting, machining barstock, swaging preformed tubing, or stamping and deep drawing flat stock to form a tubular member. The bendable sleeve-like insert may be made by machining barstock, injection moulding, extruding flat stock material and rolling it into a C-shape, or rolling a flat member into a strip and then bending it into a C-shape. In use, the ferrule may be preattached to a male-stem and accommodate a range of hose outsize diameters and embedded, hose reinforcements such as wire braid. The insert when used bends to a substantially round shape in contrast to a polygonal shape of prior art ferrules of the crushable type. Another advantage of the invention is that leakage of hose effluent is minimized by eliminating potential leak paths formed at apexes of a polygon shaped ferrule when crimped. A preferred embodiment of the present invention is now described by way of example with reference to the accompanying drawings, wherein: Fig. 1 is a side view of one form of ferrule which is outside the scope of the invention with the ferrule shown in one half axial cross-section; Fig. 2 is a view taken along the line 2-2 of Fig. 1 but showing the ferrule in full cross-section; Fig. 3 is a partial isometric view showing an insert-preform of the ferrule of Figure 1 and 2; Fig. 4 is a view of the preform of Fig. 3 bent into a sleevelike C-shape as well as a sleevelike insert that is injection moulded or machined; Fig. 5 is a partially cutaway and sectional side view of a coupled hose assembly incorporating the ferrule of Figure 1 prior to ferrule crimping; Fig. 6 is a view similar to that of Fig. 5 but showing the ferrule crimped onto a hose; Fig. 7 is a cross-sectional view taken along the line 7-7 of Fig. 6; Fig. 8 is a view similar to Fig. 7 but showing a prior art coupling with ribs formed as an integral part of the ferrule; Fig. 9 is a developed partial, internal view taken generally in the direction of 9-9 of Fig. 2 and showing circumjacently, spaced-apart edges of the C-shaped insert along its length; Fig. 10 is a view similar to that of Fig. 9 but showing the circumjacently, spaced-apart edges of the C-shaped insert after crimping such as illustrated in Fig. 6; Fig. 11 is a view similar to that of Fig. 9 but showing an alternate form of the C-shaped insert used in a ferrule according to the present invention; Fig. 12 is a view showing the inert of Fig. 11 after the coupling is crimped such as illustrated in Fig. 6; Fig. 13 is a view similar to Fig. 12 but showing the insert crimped to a smaller diameter; and Fig. 14 is a chart comparing prior art ferrule rib internal diameters with rib diameters for this invention. Referring to Figs. 1 and 2, the ferrule 10 shown therein has a tubular socket portion 12 that retains an insert 14 as a means for gripping a hose end portion. The socket portion of the ferrule has a cylindrical surface portion 16 and the insert has an outside cylindrical surface portion 18 where the cylindrical portions are positioned juxtaposed each other. The insert is retained in the socket by means of internal shoulder portions 19, 20 which have an inside diameter that is less than the outside diameter of the insert. The ferrule may optionally include a collar portion 22 as a means for pre or post attaching the ferrule to a locking collar of a male-stem. That part of the ferrule that includes the socket portion 16 may be made such as by machining from barstock, swaging or drawing a preformed tubular member, or by deep drawing and stamping flat sheet stock into a tubular shape. It is preferably formed from sheet stock for economical considerations. The sleevelike C-shaped insert includes hose gripping means on its inside surface for griping a hose end in the form of a plurality of circumferentially oriented ribs 24, 26, where some of the ribs 24 may have a greater height than other ribs 26. The insert may be made of any suitable material for gripping hose such as plastic, alloys with aluminium, and alloys with iron. The insert may be made by several different processes such as by machining it from barstock, injection molding it to a substantially C-shape shown in Fig. 4, or optionally and for economical reasons, it may be made from an elongate strip of material. Referring to Figs. 3 and 4, an elongate strip of material may be formed such as by extrusion or rolling where the strip includes a plurality of substantially parallel ribs 24, 26 which have a desired height and become means for gripping an end portion of a hose. The elongate strip is severed to a desired Length where the severed strip forms an insert-preform 27 have a length L equal to a desired circumferential length for the insert. The insert preform is rolled or bent into a C-shape as when viewed in cross-section, to define the insert with substantially circumferentially oriented ribs. The so formed insert has spaced apart edges 28, 30 along its length. The spacing between the edges is predetermined to accommodate a particular hose diameter after the ferrule is crimped. In service, the above described ferrule 10, and the ferrule of the invention, are used with a male-stem 32 which may have a locking collar 34 and a serrated stem 36 for coupling a hose 38 as shown in Figs. 5 and 6. A locking collar is typically used for hoses used in high pressure service applications. In lower pressure applications, the locking collar is not needed. The ferrule may be prepositioned over and attached to the male-stem such as by crimping it to the locking collar of the stem. This positions the ferrule substantially concentric with the stem to define an annular hose-end cavity. Such crimping retains the ferrule by bending 40 the ferrule collar 22 behind the stem locking collar 34. Alternately, the ferrule and male-stem may be stocked as two separate pieces and later attached together when coupled to a hose during crimping. A hose 38 having a tube 42, twined reinforcement 44, and cover 46 is pushed onto the serrated stem 36 as illustrated in Fig. 6. The ferrule is crushed as by crimping it with a plurality of closely arranged die fingers of a crimping apparatus, not shown, where the so crimped ferrule is illustrated by Figs. 6 and 7. As the socket portion is crushed, it slightly elongates as it is reduced in diameter. The socket portion presses radially inwardly against the sleevelike inset during the crushing process which bends the C-shaped member into substantially a round shape as shown in Fig. 7 even though the socket portion is distorted and includes a plurality of longitudinal ribs 48 formed of the socket portion and between adjacent die fingers during crimping. The spaced apart edges 28, 30 of the insert close together during the crimping operation whereby they, in some cases, may touch each other along their peripheral length. As shown in Fig. 7, the hose, and ribs formed of the insert, both bend and take a substantially round shape as does the tube, reinforcement, and cover of the hose. In contrast, and as illustrated by the prior art ferrule 50 of Fig. 8, integral ribs 52 formed of socket portion 54 distort to a substantially polygonal shape where the number of sides of the polygon are equal to the number of die fingers used in the crimping process. A straight side 55 of a polygon is formed justaposed a longitudinal rib 56 which is formed during the crimping process. It is believed that the apexes of the polygon and reinforcement form leak paths for seepage of hose effluent. The developed partial views of Figs. 9 and 10 are illustrative of how the spaced apart edges 28, 30 of the sleevelike insert 14 are initally separated (Fig. 9) before the ferrule is crimped and how the circumjacent edges 28,30 come together (Fig. 10) as the socket portion is crushed as by crimping and the sleevelike insert is simultaneously bent to substantially a round shape around a hose end portion. The developed partial views of Figs. 11, 12 and 13 are illustrative of a preferred embodiment for a C-shaped sleevelike inset 60 forming part of a ferrule according to the invention where spaced apart edges 62, 64 are in the form of spaced square cut teeth where teeth 66 of one edge are offset from circumjacently spaced apart teeth 68 of the other edge. As particularly illustrated in Fig. 11, it is also preferred that a complete portion of one or more internal ribs 70, 72 are formed as part of each tooth. Also, the so formed rib portion of each tooth may be chamfered 74,76. The angle of the chamfer may optionally be chosen so that when the insert is bent to a round shape, the chamfer generally mates with the opposite edge of the sleeve. More importantly, the chamfer inhibits the insert from gouging the hose during the crimping process as the insert is bent to a round shape. The offset teeth define a means for interdigitating with each other and advantageously provide the ferrule with a crimp range to grip hose end portions that would otherwise require several different ferrules due to variations of hose constructions. Fig. 12 is illustrative of how the teeth interdigitate with the other as the socket portion is crushed and the insert is bent to a first crimping diameter of a range of crimping diameters. As illustrated, the teeth partially overlap each other. For a minimum crimping diameter, the teeth may fully interdigitate with each other so that the peripheries of the spaced end portions are in complete contact with each as illustrated in fig. 13. To illustrate one advantage of the invention of Figs. 11-13 over that of the prior art, four different 1.27 cm (0.5 inch) ID hoses where coupled with the same type of male-stem and three different prior art ferrules having different internal rib diameters. Referring to Fig. 14, the four types of hoses were: 2 wire braid, 24132.5 kPa (3500 psi); 1 wire braid, 13790 kPa (2000 psi); 2 wire braid, 24132.5 kPa (3500 psi); and 1 wire braid, 20685 kPa (3000 psi). Before coupling, two of the prior art ferrules had a minimum rib diameter of 2.30 cm (0.906 in.) while the other prior art ferrules had internal rib diameters of 2.25 cm (0.863 in.) and 2.11 cm (0.830 in.) respectively. The coupling of the invention had a minimum rib diameter of 2.30 cm (0.906 in.). The hoses were coupled with a stem and ferrule by crimping the ferrules to their recommended crimp outside diameter. After crimping, the minimum ferrule rib diameter was measured. In the case of the prior art ferrules, the minimum diameter between the polygonal flats of the ribs was measured as well as the larger diameter that occurs between the polygonal apexes. As shown on Fig. 14, the range between the diameters for the flats and apexes of polygonal shape is approximately 0.127 cm (0.05 in.) for each hose type. The same hose types were coupled with the ferrule of the invention and the same type of prior art stem where the ferrule was crimped to its previously determined (by test) most effective outside diameter; afterwards, the minimum inside diameter of the rib was measured for each of the four hose types. The insert used in the ferrule of the present invention was bent to a substantially round shape during crimping for each of the hoses to the diameters shown on Fig. 14. As chartered the minimum diameter for the present invention falls approximately about in the middle of the range for each of the prior art ferrules. All hoses were coupled using the same type of male-stem which included a locking collar as illustrated in Figs. 5 and 6. The hoses coupled with the ferrule of the present invention were pressure tested at 32172 kPa (4,666 psi) for over 1 million cycles where the ferrules exhibited substantially very little or no leakage during the test. Accordingly, one ferrule of the present invention was used to couple four different hose types where previously, three separate ferrules were used. This emphasizes another advantage of the invention and that is that a fewer number of ferrules need be inventoried to accommodate several different types of hoses. The reason that the ferrule of the invention may accommodate a range of hose sizes with little or no leakage is believed to be partially a result of the substantially rounded shape of the sleevelike insert after crimping; also, the rounded shape in combination with interdigitating teeth of the insert member permits several hose types to be accommodated with the same ferrule. In contrast, the prior art ferrules do not bend to a round shape, but rather, are bent to a polygonal shape as the socket is crushed as by crimping. The foregoing detailed description is made for purpose of illustration only and is not intended to limit the scope of the invention which is to be determined from the appended claims.

Claims: A method of attaching an end of a hose of any one of a range of hoses having the same inside diameter but different external diameters to a hose coupling having a serrated stem comprising the steps of: (a) locating a ferrule (10), which has a tubular socket portion (12) with an insert (60) having a C-shaped cross-section located therein and which insert has an internal diameter greater than the external diameter of the end of the hose with the largest external diameter in the range of hoses, over the serrated stem (36) of the hose end coupling (32), (b) inserting the serrated stem (36) into the end of the selected hose (38), so that the insert, which has hose gripping means (70, 72) on its internal face, and which has edges (62, 64) with square cut teeth (66, 68), the teeth (68) on one edge (62) being longitudinally offset with respect of the teeth (68) on the other edge (62), so that the insert generally surrounds the end of the hose, and (c) deforming the insert (60) into locking engagement with the hose end so as clampingly to engage the hose end with the serrated stem (36), characterised in that: (d) deformation of the insert into locking engagement with the hose end is achieved by radially crushing the ferrule into engagement with the insert (60) throughout its length to cause substantially uniform bending of the insert (60) throughout its length to a desired diameter, whereby said hose gripping means (70, 72) are moved into gripping engagement with the outer surface of the end of the hose throughout the length of the insert (60), and the teeth (66, 68) are moved together and at least partially interdigitate with each other, and the hose end is deformed to be gripped by the gripping means (70, 72) and to grip the serrated stem (36) throughout the length of the insert (60). A method according to claim 1, wherein the ferrule is provided with a collar portion (22) and including the step of attaching the ferrule to the hose coupling (30) by engaging the collar portion (22) behind a locking collar (34) on the hose coupling (30). A hose coupling comprising a tubular member having a first end for connection to a fitting and a serrated male stem (36) at a second end thereof for location within an end of a hose (38) which can be selected from a range of hoses each having the same internal diameter but all having different external diameters, a ferrule (10) having a tubular socket portion (12) with an internal diameter adapted to receive an end of the hose, and a radially crushable sleevelike insert (60) of generally circular cross-section for retention in the socket portion (12) and having a length generally corresponding to that of the socket portion (12) and having an external diameter such that it fits within said socket portion, there being hose gripping means (70, 72) on the inner surface of the insert (60), characterised in that the insert (60) is of C-shape and has square cut teeth (66, 68) on opposed longitudinal edges (62, 64) thereof, the teeth (68) on one edge (64) being longitudinally offset with respect to the teeth (66) on the other edge (62) of the insert (60), and in that the socket portion (12) of the ferrule (10) is radially crushable to a desired diameter and into crimping engagement with the hose end over the whole length of the insert, so that the teeth (66, 68) move together and the teeth (66) on one edge at least partially interdigitate with the teeth (68) on the other edge and so that the hose gripping means deform the outer surface of the hose end portion and the inner surface of the hose end portion is caused to be deformed into gripping engagement with the serrated stem (36), regardless of the external diameter of the hose end portion. A hose coupling as claimed in claim 3, wherein the gripping means includes a plurality of axially spaced apart and circumferential ribs (70, 72) formed of the inside surface portion of the sleevelike insert (60). A hose coupling as claimed in claim 4, wherein a complete portion of a rib (70, 72) is formed as part of each tooth (66, 68). A hose coupling as claimed in claim 5, wherein the portion of a rib (70, 72) formed as part of each tooth (66, 68) is chamfered (74, 76). A hose coupling as claimed in any one of claims 4-6, wherein the ribs (72, 74) near the axial end of the insert which is located inside the ferrule have a height that is greater than the height of the ribs near the opposite end of the insert. A hose coupling as claimed in any one of claims 3-7, wherein the insert (60) is retained in the socket portion (12) by means of internal shoulder portions formed at opposite axial ends of the socket portion (12), the shoulder portions having inside diameters that are less than the outside diameter of the insert (60). A hose coupling as claimed in any one of claims 3-8, wherein one end (40) of the ferrule (10) is crimped into a groove in the stem (36) for attaching the ferrule (10) to the stem (36). A hose coupling as claimed in any one of claims 3-9, wherein the insert (60) is made of a material selected from the group consisting of plastic, alloys with aluminium, and alloys with iron. A hose coupling as claimed in any one of claims 3-10, wherein the socket portion (12) has an inside cylindrical surface portion, and the insert has an outside cylindrical surface portion juxtaposed the inside cylindrical surface portion of the socket portion.

Inventors: SHAH DILIP K, SHAH, DILIP K.
Applicants: GATES RUBBER CO, THE GATES RUBBER COMPANY
Application year: 1992
Main classification: F16L33
IPC codes: F16L33