Fitting for pressurized fluid lines and method for making same

A hydraulic fitting (20,120,220,320,420,520,620,720,820) [of the type for connecting pressurized fluid-conveying members includes a tubular member (22,122,222,322,422,522,622,722,822) having opposite distal ends and defining a fluid passage (24,124,224,324,424,524,624,724,824) extending between the ends of the tubular member (22,122,222,322,422,522,622,722,822).] includes [T]threaded connection portions (26,126,226,326,426,526,626,726,826) [are provided on each end of the tubular member (22,122,222,322,422,522,622,722,822) for connecting the fitting (20,120,220,320,420,520,620,720,820) with hydraulic fluid lines and the like.], and [S]sealing portions (28,128,228,328,428,528,628,728,828) [are formed] adjacent the connecting portions (26,126,226,326,426,526,626,726,826) for perfecting a fluid-tight seal between the fitting (20,120,220,320,420,520,620,720,820) and [the] associated fluid lines. A central body member (34,134,234,334,434,534,634,734,834) is disposed about the tubular member (22,122,222,322,422,522,622,722,822) and presents one or more pairs of flats (36,136,236,336,436,536,636,736,836). The tubular member (22,122,22,322,422,522,622,722,822) and connecting portions (26,126,226,326,426,526,626,726,826) are formed from a single piece of round metal bar stock, whereas the body member (34,134,234,334,434,534,634,734,834) is formed from a molded plastic material. A method is also provided for making the fitting (20,120,220,320,420,520,620,720,820).

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to fittings of the type used for 
interconnecting hydraulic, pneumatic, and other high pressure fluid lines 
and their associated hardware. 
2. Description of the Prior Art 
Fittings are often used when it is necessary to connect pressurized fluid 
lines with one another and/or with associated hardware, such as actuators, 
manifolds, and the like. Fittings of this type typically include a tubular 
member defining a fluid passage, threaded connection portions on the ends 
of the tubular member for connecting the fitting with associated fluid 
lines, sealing portions adjacent the ends for perfecting a fluid-tight 
seal between the fitting and the associated fluid lines, and a central 
body portion formed radially larger than the tubular member and presenting 
at least one pair of diametrically opposed flats for engaging a wrench 
when connecting the fitting with the fluid lines or for mounting within 
brackets of a standard fluid line clamping system for preventing rotation 
of the fitting within the brackets. 
A fitting used in such applications must have sufficient structural 
integrity to provide a leak-proof connection under high pressures. Thus, 
such fittings are commonly fabricated from any of a number of well-known 
metallic materials such as aluminum, steel, brass, etc. Examples of such 
fittings are those shown in Air-Way Manufacturing Company's Bulletin 
Number 105-78 of Olivet, Mich. Other examples include those disclosed in 
U.S. Pat. Nos. 3,414,220 granted Dec. 3, 1968 and 4,878,696 granted Nov. 
7, 1989, both to Walker. 
With all of these prior art fittings, the entire fitting is fabricated from 
metal, including the enlarged body portion. The body portion is either 
machined from bar stock and then brazed to the tubular member or, when 
possible, machined integrally with the tubular member. Examples of each 
are shown in the aforementioned Air-Way Bulletin. When forming the tubular 
member and body portion as one piece, it is common practice to begin with 
a piece of bar stock having a size and shape of the body portion. The 
one-piece fittings referenced above are made from hexagonal bar stock. The 
bar stock is then machined to form the radially smaller tubular member and 
threaded connection portions of the fitting. Examples of such fittings 
include numbers 070201, and 070119 shown in the aforementioned Air-Way 
Bulletin. Another example of this one-piece fitting for use with a 
standard plural line clamping system is shown in the previously cited 
Walker U.S. Pat. No. 4,878,696. 
Although certain benefits are realized by machining the body portion and 
tubular member as one piece rather than forming the body separately from 
the tubular member and then brazing them together, (e.g., there are no 
weld joints which are prone to leaking), this type of fitting is still 
deficient in that a large amount of material is wasted by machining the 
radially smaller tubular member and threaded connection portions of the 
fitting from the oversized bar stock or forgings. 
U.S. Pat. No. 4,854,613 to Reece et al, granted Aug. 8, 1989 discloses a 
plastic fitting having a metal internal liner. Although there is less 
wasted metal with this type of fitting over the above-described prior art 
fittings, this fitting is deficient in that the threaded connection 
portions are made from the plastic material which may be unsuitable for 
some high pressure applications. 
SUMMARY OF THE INVENTION AND ADVANTAGES 
A fitting of the type for providing a fluid-tight connection between 
pressurized fluid conveying members comprises a tubular member having 
opposite distal ends and defining a fluid passage extending between the 
ends, threaded connection means adjacent each end of the tubular member 
for threadably connecting the fitting with associated pressurized fluid 
conveying members, sealing means adjacent the connection means for 
perfecting a fluid-tight seal between the fitting and the associated 
pressurized fluid conveying members, and a body member formed radially 
larger than the connection means and tubular member and fixedly disposed 
thereabout. The invention is characterized by the tubular member and 
connection means being fabricated from a first metal material and the body 
portion being formed separately from the tubular member from a second 
moldable material different from the first material. 
A method is also provided for making a fitting for high pressure fluid line 
applications. The method includes forming a tubular member out of a first 
metal material having opposite distal ends and forming a fluid passage 
within the tubular member extending between the ends thereof. Threaded 
connection portions are formed of the same first metal material on the 
ends of the tubular member for providing a threaded connection with 
associated high-pressure fluid conveying members. Sealing portions are 
formed adjacent the ends of the tubular member for providing a fluid-tight 
seal between the fitting and the associated high pressure fluid conveying 
members. A body member is formed radially larger than the tubular member 
and connection portions out of a second moldable material different than 
the first metal material and is fixedly disposed about the tubular member. 
The subject fitting has many advantages over the prior art fittings. 
Firstly, the subject fitting accounts for the tremendous amount of waste 
associated with forming the prior art one-piece type fittings. The subject 
fitting significantly reduces material waste by forming the radially 
larger body portion as a separate molded member rather than as an integral 
structure of the fitting. Thus, initially smaller size bar stock may be 
used to form the tubular member and connection portions as compared with 
the oversized bar stock material used with the prior art fittings. 
Another advantage of the subject fitting is that the body portion can be 
molded from a lightweight material such as plastics to produce a 
relatively lighter weight fitting. 
Yet another advantage of the subject invention is that the configuration of 
the body portion is not limited to the size and shapes of commercially 
available bar stock as with the prior art one-piece fittings. The molded 
body portion can be of whatever size and shape as required by the specific 
application. 
Still another advantage of the subject fitting is that it is less expensive 
to produce. The lower cost can be attributed to less waste, less machining 
time and the use of less costly materials.

DETAILED DESCRIPTION OF THE DRAWINGS 
The subject invention generally relates to fittings of the type for 
connecting two or more fluid lines together or for connecting fluid lines 
with its associated hardware, such as actuators, manifolds, and the like. 
These fittings are particularly suitable as hydraulic fittings for machine 
tools and the like but may be equally suitable for other high pressure 
fluid applications. 
Turning now to the enclosed figures, a first embodiment of a fitting 
constructed in accordance with the present invention is generally shown at 
20 in FIGS. 1 and 2. The fitting 20 comprises a tubular member 22 having 
opposite distal ends and defining a fluid passage 24 extending between the 
ends of the tubular member 22. The tubular member 22 of FIGS. 1 and 2 is 
constructed from a single, continuous piece of round metal bar stock 
(i.e., bar stock having a circular cross-section). In the alternative, a 
forged piece of stock could be used. The particular type of metal selected 
will depend on the specific application, but may include such metals as 
brass, steel, aluminum, and the like. The fluid passage 24 is preferably 
bored into the fitting 22 by a conventional machining operation. 
Each end of the tubular member 22 is formed with threaded connection means 
26 for threadably connecting the fitting 20 with associated pressurized 
fluid conveying members (not shown), including high pressure fluid lines 
and associated hardware such as manifolds, actuators and the like. The 
threaded connection means 26 are preferably threaded connection portions 
or regions 26 (i.e., screw threads) machined integrally on the exterior 
surface of the tubular member 22 near or at each end of the fitting 20 out 
of the same piece of round bar stock material. If the screw threads 26 are 
to be external male threads 26 as shown, the bar stock selected should be 
large enough to accommodate these threads 26. The threads 26 could also be 
of the internal female type (not shown). 
The fitting 20 further includes sealing means 28 formed adjacent the 
connection means 26 for perfecting a fluid-tight seal between the fitting 
20 and the associated pressurized fluid conveying members (not shown). The 
sealing means 28 may comprise a 37 degree or 45 degree flare or conical 
surface 30 formed on one or both ends of a fitting 20. This is shown to 
the left of FIGS. 1 and 2. Alternatively, a male O-ring type seal may be 
used. The O-ring seal is formed as a flat, perpendicular O-ring seat or 
surface 32 on the fitting 20 as shown to the right of FIGS. 1 and 2. An 
O-ring 33 is disposed about the tubular member 22 adjacent the O-ring seat 
32 for perfecting a fluid-tight seal between the fitting 20 and its 
associated pressurized fluid conveying members (not shown). 
Other end fitting configurations and combinations thereof known to the 
industry are also contemplated such as those illustrated in the Air-Way 
Manufacturing Co. Bulletin #105-78, and the ones described are just 
exemplary. 
The fitting 20 further includes a body member or portion 34 formed radially 
larger than the tubular member 22 and threaded connection portions 26 and 
fixedly disposed about the tubular member 22. The body member 34 defines 
tool engaging surfaces 36 for engaging a wrench or other support during 
installation of the fitting 22. The body member 34 of FIGS. 1 and 2 has a 
hexagonal cross-section and presents three sets of diametrically opposed 
flats 36 as the tool engaging surfaces 36. These flats 36 are adapted for 
engaging a wrench or similar device when connecting the fitting 20 with 
the associated fluid lines. The body member may take on any of a number of 
different shapes suitable for a particular application. 
The body member 34 is formed separate from the tubular member 22 and of a 
second different material than the tubular member 22. More specifically, 
the body member 34 is formed of a rigid moldable plastic material and is 
molded about the tubular member 22 to define a distinct portion of the 
fitting 20 fixedly joined to the tubular member 22. The plastic material 
could include polymers, resins, or similar materials which could withstand 
the forces applied to the body member 22 by the wrench during installation 
and servicing of the fitting 20. 
As can be seen best in FIG. 2, the O-ring seat 32 may also be molded 
integrally with the body member 34 out of the same material. 
The fitting 20 also includes mechanical bonding means 38 formed integrally 
on the outer surface of the tubular member 20 for mechanically bonding 
with the body member 34 upon molding the same about the tubular member 20. 
The mechanical bonding means 38 comprises a gripping surface in the form 
of a knurled surface 38 formed on the outer surface of the tubular member 
22 intermediate the ends thereof. The knurled surface 38 presents a 
pattern of crisscrossing grooves and ridges which mechanically interlock 
with the molded body member 34 to prevent relative axial and rotational 
movement between the body member 34 and the tubular member 22. 
Turning now to FIGS. 3 and 4, a second embodiment of a fitting constructed 
in accordance with the present invention is generally shown at 120, 
wherein like numerals are used to represent like parts, but are offset by 
increments of 100 throughout the Figures to distinguish the various 
embodiments of the present invention. The materials used for the tubular 
member, connection portion and body member for each of the various 
embodiments to be described below are preferably the same as those used in 
the first embodiment of FIGS. 1 and 2 described above. 
The fitting 120 is identical to the fitting 20 of the first embodiment 
except that it is bent so that a 45 degree elbow 140 is formed 
intermediate the ends of the tubular member 122. That is, the tubular 
member 122 of FIGS. 3 and 4 is bent or angled 45.degree. away from its 
central axis so that a 135.degree. angle is formed between the tube ends. 
Fittings having this angular relationship are commonly referred to in the 
industry as "45.degree. fitting", as exemplified by the identification of 
such fitting types in the above-mentioned Air-way Bulletin #105-78. 
Bending the tubular member 122 preferably takes place prior to molding the 
body member 134 about the tubular member 122. In fact, the body member 134 
is molded about the elbow 140 and is itself shaped with an elbow to 
conform with the tubular member 122. This one-piece 45 degree fitting 120 
provides a smooth, uninterrupted fluid passage 124 within the fitting 120. 
Two alternative 45 degree elbow fittings are illustrated in FIG. 5 and 6. 
The fitting 220 of FIG. 5 comprises a two-piece tubular member 222 having 
first 242 and second 244 leg sections formed of round metal bar stock and 
directly joined to one another to form the 45 degree elbow 240. To form 
the elbow 240, the adjoining ends of the leg sections 242,244 are each cut 
at a 22.5 degree angle and then joined together (such as by brazing) to 
create the desired 45 degree elbow 240. The threaded connection portions 
226 and flared sealing portions 228 are preferably formed on the 
individual leg sections 242,244 prior to joining the leg sections 242,244 
together. The body member 234 is molded about the elbow 240 in the same 
manner as with the previously described 45 degree fitting 120. 
The fitting 320 of FIG. 6 comprises a three-piece 45 degree tubular member 
322 having first and second leg sections 342,344 formed of round metal bar 
stock and joined together by a separate third elbow piece 346. With this 
type of fitting 320, the leg sections 342,344 are first formed with the 
threaded connection portions 326 and flared sealing portions 328 and then 
joined to the separate and distinct elbow piece 346 which is bent or 
curved 45 degree to establish the desired 45 degree elbow 340 in the 
fitting 320. The leg sections 342,344 and elbow piece 346 may be welded or 
brazed together in the same manner as the leg sections 242,244 of the 
two-piece 45 degree fitting 220 of FIG. 5. Once the leg sections 342,344 
and elbow piece 346 are joined, the body member 334 is molded about the 
elbow 340 in the same manner as previously described. 
FIGS. 7 through 10 show three additional embodiments of fittings 
420,520,620 constructed in accordance with the present invention. These 
fittings 420,520,620 are identical to the fittings 120,220,320 of FIGS. 3 
through 6, respectively, except that the fittings 420,520,620 are formed 
with a 90 degree elbow 440,540,640 rather than a 45 degree elbow 
440,540,640. The 90 degree elbow 440,540,640 may be formed in any one of 
the three ways described above for the 45 degree fittings 120,220,320 with 
the tubular member 422,522,622 comprising a one, two or three-piece 
tubular member 442,522,622 as illustrated in FIGS. 8, 9 and 10, 
respectively. 
FIGS. 11 through 13 show two special types of fittings 720,820 adapted to 
be mounted within a standard plural line clamping system 52 well-known to 
the art. These fittings, 720,820 are similar to those described in FIGS. 1 
through 10 above except that the fittings 720,820 include extra collar 
portions 762,862 for mounting the fittings within the clamping system 52, 
as will be described in more detail below. 
FIGS. 11 and 12 illustrate one of the two disclosed fittings 720 
constructed in accordance with the present invention and adapted to be 
mounted within the standard plural line clamping system 52 shown in FIG. 
14. This fitting 720 includes a one-piece tubular member 722 of round 
metal bar stock formed with a fluid passage 724 extending between opposite 
ends of the tubular member 722. The fitting 720 is provided with external 
male threaded portions 726 adjacent each end of the fitting 720 as the 
connection means 726 and further includes flared ends as the sealing means 
728. The tubular member 722 also includes a knurled, external surface area 
738 formed on the outer peripheral surface of the tubular member 722 
intermediate the ends thereof as the mechanical bonding means 738. 
Like the fitting 20 of FIGS. 1 through 2, the tubular member 722 is 
preferably formed from a single piece of round metal bar stock of a size 
large enough to form the threaded portions 726. Likewise, the fitting 720 
includes a body member 734 formed radially larger than the tubular member 
722 and disposed thereabout on the knurled surface 738 of the tubular 
member 722. The body member 734 can be made from the same materials 
described for the body members of FIGS. 1-10. The body member 734 is 
formed with a hexagonal cross section having three pairs of diametrically 
opposed tool engaging surfaces in the form of wrench flats 736. 
The fitting 720 is adapted to be mounted between a pair of inverted 
U-shaped brackets 50 of the standard plural line clamping system 52, with 
each bracket 50 including a pair of spaced apart side walls 52 and a 
connecting wall 54 therebetween. The flats 736 of the body member 734 are 
adapted to engage a pair of adjacent fasteners 56 of the clamping system 
52. The typical fasteners 56 for a standard plural line clamping system 52 
include internally threaded barrels or spacers 58 disposed within and 
separating the U-shaped brackets 50. Bolts 60 are then screwed into the 
threaded barrels 58 to clamp the brackets 50 together. When clamped 
between the brackets 50, the flats 736 of the body member 734 are in 
abutting contact with the threaded barrels 58 which prevents rotation of 
the fitting 720 within the brackets 50. 
The fitting 720 is further provided with two cylindrical collar portions 
762 formed radially smaller than the body member 734 and disposed on 
opposite axial sides of the body member 734. The collar portions 762 are 
preferably formed integrally with the body member 734 out of the same 
material. The cylindrical collar portions 762 are adapted to be clamped 
between a pair of opposed semi-cylindrical clamping seats 64 formed on the 
outermost extent of the side walls 54 of the brackets 50 to securely mount 
the fitting 720 between the brackets 50. 
FIG. 13 shows a fitting 820 which is identical to the fitting 720 of FIGS. 
11 and 12 except that the body member 834 has a different shape. The body 
member 834 is generally rectangular in cross section with two sides of the 
rectangle forming a pair of diametrically opposed wrench flats 836 and the 
other two sides being generally rounded 866. 
The invention has been described in an illustrative manner, and it is to be 
understood that the terminology which has been used is intended to be in 
the nature of words of description rather than of limitation. 
Obviously, many modifications and variations of the present invention are 
possible in light of the above teachings. It is, therefore, to be 
understood that within the scope of the appended claims wherein reference 
numerals are merely for convenience and are not to be in any way limiting, 
the invention may be practiced otherwise than as specifically described.