Compensating hose fitting
BACKGROUND OF THE INVENTION 
     This invention relates to permanent hose fittings of the socket and insert type which are crimped or swaged onto hose having inner and outer layers of rubber-like material and one or more intermediate layers of wire reinforcement. 
     Both permanent and reusable hose fittings are well known in the art and typically are characterized further as being of the skive or no-skive variety referring to whether the outer cover of the hose is removed or not to achieve a desired engagement between the inner surface of the socket and the reinforcement or outer cover material. It is the usual practice with relatively high pressure rubber hose to assure that a direct engagement is made between the socket and wire reinforcement so that a secure grip is made upon the hose. This can be done either by the prior step of skiving the hose to expose the reinforcement or by the use of projections on the interior surface of the socket which penetrate the cover and directly engage the reinforcement. 
     One example of a permanent hose fitting is shown in U.S. Pat. No. 4,106,526. This typifies one form of prior art device in which the hose is prepared for coupling by skiving of the outer cover. 
     Another form of prior art is described in U.S. Pat. No. 3,287,033, this being a reusable type fitting in which the socket is threaded over the cover of the hose and the insert later added. This art is significant however in that the hose need not be prepared by skiving, in that threads on the socket are designed to cut through the cover and directly engage the wire reinforcement. In this arrangement the socket threads are relatively strong and are adapted to bite into and deflect the wire reinforcement in a preferred undulating pattern between the socket projections which provides a superior grip by utilizing the sharp edges of the socket thread. 
     One form of permanent fitting adapted to pierce the cover and engage the reinforcement of the hose is shown in U.S. Pat. No. 4,064,614, wherein pyramidal barbs are employed. These barbs are sharply pointed and have a sturdy base and would tend to move radially into the reinforcement upon crimping or swaging without deflecting either the reinforcement or the barbs. 
     Another form of permanently attachable fitting is disclosed in U.S. Pat. No. 2,797,111 wherein again, generally radially disposed projections are included in the socket to engage the reinforcement. The projections deform upon crimping or swaging in some embodiments apparently in an uncontrolled manner. Further the projections are in the form of threads which slice into the cover upon initial placement of the fitting. 
     SUMMARY OF THE INVENTION 
     The permanent fitting of the instant invention is of the non-skive type and may be utilized in a crimped or swaged assembly and is designed primarily for field attachment. The fitting includes a socket and insert, the socket having a plurality of inner, axially spaced annular projections which are adapted to pierce the cover of the hose, engage the reinforcement and be bent in a controlled manner into a preferred gripping orientation. The projections are shaped to control bending and have inner and outer flanks and a relatively blunt tip, but sharp intersecting edges therebetween. In one embodiment of the invention the outer flanks are disposed at an angle of about 20° with respect to a transverse plane, leaning toward the inner portion of the socket and adapted to be bent even further upon engagement with the reinforcement. 
     This controlled bending provides a device for accommodating for variations in hose sizes and for machining or crimping differences in the metal fitting. It allows for the use of a limited number of crimp diameters when working with different sized hose in both single and plural layer reinforcement styles. Further, a superior inner crimp configuration of more nearly circular shape is achieved with this hose fitting by means of heat treatment of the metal. This is provided by process annealing of the socket to achieve a desired softness so that even though a polygonal outer surface occurs in crimping, a more circular inner configuration is produced, providing superior integrity for the fitting. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a longitudinal view of the crimped fitting of the invention, partly in cross section, showing an end portion of a hose secured therein; 
     FIG. 2 is an enlarged sectional view of a portion of the crimped fitting with hose secured therein, showing the relationship of the socket prior to crimping, in dashed lines; 
     FIG. 3 is an end view of the crimped fitting taken along the lines of 3--3 of FIG. 1, showing the relationship between outer and inner surfaces; and 
     FIG. 4 is an enlarged sectional view of a portion of the fitting prior to crimping. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, the hose fitting 10 of this invention is shown in crimped form as comprising a body member 11 having a connector nut 12 crimped thereto at one end for attachment to an external device utilizing fluid under pressure, an integral insert portion 14 at the other end, and a communicating bore 15. Wrench flats 16 in the form of a hex are disposed in the central port of the body member as is annular groove 18, receiving end ring 19 of socket member 20. The end of a hose 21 is shown crimped within the fitting 10 and as seen more clearly in FIG. 2 consists of an inner core 22, a section of wire reinforcement 24, and outer cover 25. 
     Insert 14 is a generally tubular member and in the preferred embodiment of the invention is depicted as integral with body member 11, and including a plurality of axially spaced annular barbs 26. The configuration of the external surface of the insert may as well be smooth or ribbed or other convenient shape as the primary function of same is to provide support for the interior of the hose 21 and a seal therewith, rather than to assist appreciably in resisting pull-out of the hose. 
     Socket 20 primarily provides the gripping function of the fitting 10 through the action of projections 28 on the internal surface thereof. Socket 20 is generally tubular having ring 19 at the inner end thereof for effecting a tight interconnection with body member 11, however the socket 20 could be machined as well from material forming body member 11 to provide an integral structure. Groove 18 in body member 11 preferably includes tapered side wall 29 so as to provide an interference fit when ring 19 is compressed therein although this could be accomplished as well by providing a tapered wall on the ring 19, or on both the ring 19 and groove 18. 
     The interference fit or solid interlock between socket 20 and body member 11 is necessary to eliminate play or relative movement between the socket 20 and insert 14 once the hose assembly is made and pressure applied. Such movement, if not prevented, could greatly shorten the life of the assembly by causing &#34;working&#34; of the core tube 22, causing it to work itself out of the compressed area, wear or crack in fatigue. Also any relative movement between socket 20 and body member 11 allows striking of the parts every time that pressure is applied, subjecting the parts to fatigue and shear in service. 
     Socket 20 extends, prior to crimping as seen in dashed lines in FIG. 2, so that the free end 30 thereof generally overlies, but does not protrude beyond the end of insert 14, forming an annular recess between it and the insert 14 for receipt of hose 21. The inner surface of socket 20 includes a plurality of projections 28 which may be ring-like ribs, a spiral thread or threads or a very fast helical thread extending almost fully axially of the fitting. In the embodiment of the invention shown the projections 28 are threads having a very slow helix so that the projections 28 extend almost transversely of the axis of the fitting 10. A current preferred embodiment of the invention utilizes transverse ring-like ribs for the projections 28. 
     As seen most clearly in FIG. 4 each projection 28 includes an inner side or flank 31, an outer flank 32 and a tip portion 34 therebetween. Inner flank 32 is disposed at a slight angle 35 outwardly with respect to a plane transverse to the central axis of the fitting. This angle 35 is of a minimum taper just sufficient to supply clearance for machining purposes and is on the order of 10° or less, in this embodiment being 3°. Outer flank 32 is disposed at a greater angle 36, in this instance inwardly and being on the order of 20°. Both flanks 31, 32 intersect generally flat but relatively blunt tip portion 34 in relatively sharp edges 38, 39 respectively. 
     The depth dimension of the projections 28 is dependent upon the thickness and type of cover 24 of the hose 21 to which the fitting is to be joined. In this embodiment the depth of projection is on the order of 1/10 inch and it has been determined that the depth should be approximately 0.015 inch greater than the maximum thickness of the cover 25 at any point. 
     The profile for the projections 28 of angled flanks 31, 32 provides a biased profile creating a tendency for the projection to bend in a pre-selected direction when it is brought into contact with the reinforcement 23. As seen in FIG. 2 as projections 28 are moved inwardly to engage the reinforcement 23, they will be bent in a leftward direction tending to tighten the grip on the hose 21 to trap same within the annular recess, the projections assuming the positions depicted at 28a with the sharp edges 38, 39 thereof embedded in the reinforcement 23, and with the latter in a slight undulating configuration, between the projections 28, enhancing the bite by the edges 38, 39. 
     It is noted in FIG. 2 that as the socket 20 is deformed the projections 28 move not only radially inwardly but also axially outwardly. This is seen as projection 40 moving to the position of projection 40a, while projection 41, toward the outer end of the socket 21, moves even further axially to the position depicted at 41a. Such axial movement occurs due to the fact that the socket 21 elongates so it becomes smaller in diameter and that a cumulative effect is produced at the outer projections. This movement, however, causes the projections 28 to strike the reinforcement at a slight angle rather than absolutely perpendicular, and augments the bending tendency of the projections 28, provided by the biased profile effected by angled flanks 31, 32. 
     The dimension of tip 34 of projection 28 should be limited to control the bending effect and a width on the order of less than 1/32 inch between edges 38, 39 is appropriate for hose on the order of 3/8 inch inside diameter. For hose such as SAE standard 100R1, such dimensions would be suitable while the projections would be spaced axially apart on the order of 1/4 inch, on centers. 
     As previously indicated, projections 28 could as well be ring-like or transverse or in a faster helix and almost axial and with a similar biased profile provided by similar angled flanks, and produce much the same bending tendency and grip upon the reinforcement of the hose. Suitable modifications in dimensions might be necessary, however, the same general forces and relative movements between parts of the fitting 10 will occur to produce a similar gripping configuration. 
     One of the prime advantages of the fitting 10 of this invention is the compensation thus effected in accommodating for hose manufacturing and fitting machining tolerances. The projections 28 bite through the cover 24 of the hose 21 to engage the reinforcement 23 and then create the compensation in bending to a final position. The effect is that of &#34;pressure-crimping,&#34; a technique of assembly in which crimping is continued only until a predetermined &#34;pressure&#34; or force of resistance is realized. This type of crimping produces excellent results but is unsuited to unskilled use in the field, and it is advantageous that the fitting 10 of the instant invention achieves some of the same effects, without requiring force-sensing equipment, and the like. 
     But another advantage of the fitting 10 is the simplification afforded in the crimping operation, because of the compensation effect. For example, the same size fitting 10 can be provided for single braid or double braid hose such as the SAE standard 100R1 and 100R2 types. All that is required is that the crimp diameter of the fitting socket 21 be adjusted to accommodate the additional layer of wire braid or larger diameter of braid and in fact for the various hose sizes only one adjustment is required between single and double wire braids which can be used for all sizes. This greatly simplifies the procedures required of field personnel and reduces the chances for error. Without the compensation effect, adoption of a single adjustment to accommodate the additional layer of wire braid in all sizes would require compromise, being too great in the small sizes and too little in the large sizes. 
     It is important with any hose fitting that the socket be very nearly circular at the points where it grips the hose, to minimize leakage. In the crimping operation however, the individual crimp fingers tend to create a polygon on the inside surface rather than a circle, because of the point contacts on the outside diameter, rather than a continuous contact around the periphery. It has been determined however, that this tendency can be altered by proper heat treatment of the socket. If the socket 31 is left in the half-hard condition best suited to machining, a polygonal shape is produced at the inside surface, but if the socket 21 is properly annealed then the gripping surface becomes more circular after crimping. 
     As seen in FIG. 3, the outside surface of the socket 21 is a series of eight arcs 44 formed by the configuration of the crimp fingers of a crimping machine, joined by intermediate relief protrusions 45 caused by the lack of continuity between the crimp fingers, and which consists of material which has not been crimped as far as the arcs 44. The inner surface of the socket 21, between projections 28, shown in dashed lines 48, is generally polygonal and this configuration would also be produced at the tips 34 of the projections if half-hard steel were used for the socket 21. However, by annealing properly, the tip 34 location is generally circular, providing a superior grip upon the reinforcement 23. In a preferred embodiment of this invention, socket 21 is made of C12 L14 steel and is softened to a maximum of Rockwell B70 by process annealing.