Ferrule, coupling and process

A ferrule for use with a male stem which together define a coupling for flexible hose, the ferrule including a sleeve having an inside surface from which extend a plurality of longitudinally oriented ribs that are circumferentially spaced from each other. The ferrule is preferably made by extruding a metal tube and forming a plurality of longitudinal ribs, circumferentially spaced from each other along thetube inside surface; and cutting the tube in desired lengths to define ferrules.

BACKGROUND OF THE INVENTION 
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 longitudinal ribs formed on its inside 
surface. 
Couplings post assembled to 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. The coupling is retained by 
pinching the hose end between the ferrule and stem. This is accomplished 
by either the effects of radially reducing the size of the ferrule or a 
radial increase in the male stem. 
Sealing and retaining a coupling to a high pressure hose subjected to 
impulses may be accomplished by using a serrated stem with a ferrule 
locking collar. The ferrule may be pre-attached such as by crimping an end 
portion to the collar so that the annular hose receiving cavity is formed 
or a separate ferrule with an internal collar may be provided to attach 
behind the stem collar when the ferrule is crimped. 
Circumferential or helical ribs or threads are oftentimes provided on the 
inside of the ferrule to cause undulations in or to make surface contact 
with a twined hose reinforcement in conjunction with a serrated stem. 
The ferrule locking collar, serrated stem, and ferrule with either helical 
or annular ribs represent techniques used to withstand high end forces 
while simultaneously providing a coupling hose seal. For example, a 
coupling for use with a one-half inch (I.D.) hose having an 8,000 psi 
burst pressure must withstand end forces of approximately 3/4 ton without 
leaking. Some ferrules using helical or circumferential ribs require the 
cover to be skived from the hose so the ribs can make direct surface 
contact with a reinforcement such as braided wire. Other ferrules have 
sharp annular or helical ribs which cut through the cover and make surface 
contact with the reinforcement during a crimping operation. In either 
case, the ferrules are sometimes difficult to install over a flared 
reinforcement at the hose end when annular or helical ribs of the ferrule 
circumferentially engage the reinforcement. Also, such ferrules are 
oftentimes expensive because the ferrule must be turned from bar stock to 
the desired configuration. 
The ferrule of the invention is intended for use with the various types of 
couplings and the process for making the ferrule eliminates several 
machining operations. 
SUMMARY OF THE INVENTION 
In accordance with the invention, a ferrule for use with a hose coupling is 
provided as a sleeve with a plurality of longitudinal ribs extending from 
its inside surface. The ribs are circumferentially spaced from each other. 
In use, the ferrule is arranged coaxially with a male stem. The ferrule 
and stem define an annular cavity for receiving a hose end. A plurality of 
teeth are formed at one end of the sleeve from the ribs to define a 
serrated collar that attaches behind a collar of the stem to secure the 
ferrule (such as when crimping the ferrule). 
The ferrule may be made by extruding a tube and forming a plurality of 
longitudinal ribs along its inside surface. Ferrules of desired length are 
cut from the tube. Optionally, one end of the ferrule may be internally 
chamfered. 
The longitudinally oriented ribs of the ferrule pinch the hose in 
cooperation with the male stem and provide a hydraulic seal. Unexpectedly, 
the longitudinal ribs of the ferrule of the invention do not provide a 
leakage path for hose effluent. The ribs provide sufficient surface 
contact with the hose reinforcement for coupling retention and the ferrule 
makes sufficient pressure contact with the stem to provide the necessary 
sealing capability. 
An object of the invention is to provide a hose ferrule which does not 
require extensive machining operations but yet exhibits comparable 
hydraulic performance to an extensively machined ferrule when subjected to 
rigorous pressure cycling such as exemplified by SAE 100Rl hose standards.

DESCRIPTION OF PREFERRED EMBODIMENTS 
Referring to FIGS. 1 and 2, the ferrule 10 of the invention includes a 
sleeve 12 having an inside surface 14 from which project a plurality of 
longitudinal ribs 16. The ribs may either be circumferentially 
asymmetrically spaced, or more preferably, the ribs are circumferentially 
symmetrically spaced. The ribs are substantially straight and generally 
axially oriented with the sleeve axis. The substantially straight ribs 
extend longitudinally preferably a major length of the sleeve. 
The cross section of the rib and inside surface of the sleeve are chosen to 
be compatible with the hose to be coupled. The ribs may have a generally 
triangular cross section 18 and form an apex which may be used to bite 
through the cover of a hose to make surface contact with an embedded 
reinforcement as will later be explanied. For some types of hoses, for 
example plastic hose, it is desirable for the ribs not to penetrate the 
cover. In this situation, ribs having a sector cross section 20 such as 
exemplified by FIG. 4 may be used. The sleeve may have any desired inside 
surface shape. For example, the inside surface may be generally chordal 22 
between the ribs such as shown in FIG. 4 or it may be substantially 
cylindrical such as shown in all other Figures. 
In some coupling applications, it is desirable that at least one end of the 
sleeve has an internal chamfer 24 which forms a stress relief for a 
coupled hose. Additionally, the internal chamber of the sleeve may be 
extended to bevel 26 the end portions of the ribs. Various combinations of 
chamfering and beveling may be used with chamfering to obtain a desired 
stress relieve such as shown for example in FIG. 3. 
The other end of the sleeve may be used to define means for attaching the 
sleeve to a locking collar of a hose stem. For example, an internal collar 
28 may be formed on the sleeve (FIG. 3). Optionally, a transverse groove 
30 may be formed in the end portions of the ribs as shown in FIG. 2 to 
define a serrated collar 32 for attaching to the locking collar of a stem. 
The so-formed groove then defines a plurality of teeth 34 that may engage 
the locking collar. The teeth may be formed by machining, but more 
preferably, the teeth are formed during a crimping operation as will later 
be explained. 
The ferrules of FIGS. 1-4 may be formed by any of the known ferrule 
producing techniques such as by machining, broaching, cold forming or 
turning. However, the economical advantages of the invention are most 
significantly realized when the sleeves and ribs are simultaneously 
extruded. 
Referring to FIG. 5, the ferrules are made by extruding a tube 36 while 
forming a plurality of circumferentially spaced, longitudinal ribs 16 
along the inside surface 14 of the tube. The outside of the tube may be 
cylindrical as shown or have any desired extrudable shape. Any of the 
extrudable high modulus materials may be used such as steel, aluminum, 
magnesium, brass and plastic. The tube is then cut into desired lengths L 
to define a plurality of ferrules. The cutting may be accomplished in any 
known manner such as by turning, sawing or shearing. A turning operation 
allows the economic forming of an internal chamfer on one or both ends of 
the ferrule at minimum cost. The turning operation also allows beveling 
end portions of the ribs as an extension of the internal chamfer should it 
be desired. Similarly, circumferentially spaced teeth may be formed from 
the ribs by machining the transverse groove 30 to define the internal 
serrated collar. 
In service, the ferrule is used with a male stem 38 having a locking collar 
40 and optionally, a serrated stem 41 for coupling a hose 42 having a tube 
44, twined reinforcement 46 and cover 48 as shown in FIGS. 6, 7 and 9. The 
locking collar is used when the service applications require high pressure 
operation. In lower hose pressure applications, the teeth may not be so 
formed and the locking collar need not be used. The ferrule may be 
prepositioned on and attached to the male stem by crimping around the 
ferrule attaching collar. This positions the ferrule substantially 
concentric with the stem to define an annular hose-end cavity. The 
crimping extrudes portions of the ribs around the locking collar to define 
the teeth 34. 
Optionally, but preferably, the ferrule is not preattached to the stem, but 
rather it is inserted over the hose end and the stem is inserted in the 
hose bore as shown in FIG. 6. The ferrule is crimped against the locking 
collar which forms the locking teeth 34, behind the collar 40 as shown in 
FIGS. 7 and 8. When sharp ribs are used, they cut through the hose cover 
and make surface contact with the reinforcement. A wire reinforcement will 
partially embed 50 into the ribs. The ribs should be from about 33 percent 
to about 75 percent of the thickness of the hose cover to cut through the 
cover and contact the reinforcement. The ribs contact the reinforcement 
pushing it radially inward which displaces portions of the cover and tube 
to make the reinforcement assume a polygonal shape 52 as shown in FIG. 9. 
This forces the tube in tight relationship with the stem to effect a seal 
therewith. The teeth 34 hold the ferrule to the collar 40 while the ribs 
16 grip the reinforcement 46 securing the hose 42 to the ferrule 10. 
The foregoing procedure was described for a "noskive" operation. If 
desired, the cover may be removed to expose the reinforcement so that the 
ribs do not have to cut through the cover. The rib height and shape may 
have to be changed. 
When a textile reinforced hose is used, the ribs as shown in the ferrule of 
FIG. 4 are preferred since contact with the reinforcement is probably to 
be avoided. The sector-shaped ribs displace the cover tube and 
reinforcement to effectively retain the stem. 
To illustrate; a satisfactory ferrule for use with SAE 100Rl wire braid 
hose is designed to operate at 2,000 psi working pressure and have an 
8,000 psi burst with a minimum 150,000 cycle life, the following ferrule 
was used: 
Sleeve I.D., mm: 24.1 
Sleeve O.D., mm: 27.9 
Rib Height, mm: 2.0 
Crimp O.D., mm: 23.9 
The ferrule was used with a prior art serrated stem and exhibited 
satisfactory performance. 
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.