U.S. patent number 3,837,205 [Application Number 05/384,441] was granted by the patent office on 1974-09-24 for process for cold forming a metal tube with an inwardly thickened end.
Invention is credited to Joseph A. Simon.
United States Patent |
3,837,205 |
Simon |
September 24, 1974 |
PROCESS FOR COLD FORMING A METAL TUBE WITH AN INWARDLY THICKENED
END
Abstract
Placing a short tubular metal blank into an open die, having an
inner, annular extrusion shoulder, and partially pressing the blank
through the shoulder to extrude an elongated, uniform wall
thickness tube portion. Then placing a second blank into the die in
end to end contact with the remaining portion of the first blank,
and pressing the second blank similarly part way through the die
extrusion shoulder to simultaneously extrude the remaining portion
of the first blank through the shoulder to form it with the same OD
as its first extruded portion, but with a smaller ID, to form an
inwardly thickened end portion on the extruded part, while also
extruding the uniform wall thickness portion on the second blank,
and then repeating the cycle.
Inventors: |
Simon; Joseph A. (Grosse Point
Farms, MI) |
Family
ID: |
23517329 |
Appl.
No.: |
05/384,441 |
Filed: |
August 1, 1973 |
Current U.S.
Class: |
72/260; 74/607;
72/370.02 |
Current CPC
Class: |
B21C
23/14 (20130101); B21K 1/06 (20130101); Y10T
74/2188 (20150115) |
Current International
Class: |
B21C
23/02 (20060101); B21K 1/06 (20060101); B21C
23/14 (20060101); B21c 025/08 () |
Field of
Search: |
;72/253,267,260,370,367 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Lanham; C. W.
Assistant Examiner: Rogers; Robert M.
Attorney, Agent or Firm: Cullen, Settle, Sloman &
Cantor
Claims
Having fully described an operative embodiment of this invention, I
now claim:
1. A process for extruding a tubular metal part having an inwardly
flared end portion, in a press, having a support base and a
pressure ram movable towards said base, comprising:
positioning a relatively short tubular blank within a die mounted
upon the base in alignment with the ram, the die having an open
inlet end with a blank receiving portion and an outlet end having
an inwardly extending annular shoulder whose inner cross-sectional
dimension is smaller than that of the blank receiving portion to
form an extrusion throat, and with the die being open at the outlet
end for passing the extruded blank therethrough;
ram pushing the blank partway through the die shoulder for thereby
extruding a portion of the blank therethrough to form a
substantially uniform, relatively thin wall tubular barrel portion
on the blank, with the end portion of the blank remaining in the
die blank receiving portion thereby forming an outwardly flared,
that is, thicker outwardly extending wall portion on the blank
end;
next, inserting a second, identical blank into the die blank
receiving portion in end to end contact with the first mentioned
blank;
then ram pushing the second blank towards the die shoulder, thereby
forcing the said end portion of the first mentioned blank
completely through the die shoulder and out of the die outlet
opening, to simultaneously force the thicker wall portion thereof
to move radially inwardly, that is, causing the thicker wall
portion to reverse and extend inwardly relative to the said barrel
portion, so that the now finished extruded first blank is formed as
an elongated tube of uniform external cross-section and with its
inner cross-sectional shape having a portion which is of smaller
cross-sectional size at an end of the tube, relative to the inner
cross-sectional size of the remaining portion of the tube;
and then continuing the ram pushing of said second blank to repeat
the steps of pushing the blank partway through the die shoulder and
then repeating the cycles of inserting a new blank and ram pressing
for thereby continually extruding such tubular parts.
2. A process as defined in claim 1, and including the step of
accurately sizing the inner cross-sectional periphery of the
tubular part by connecting upon the ram a pre-sized punch portion
so that the ram punch portion is arranged within the blank opening
and extends through the shoulder during the ram pushing of the
blank through the shoulder for controlling and holding the inward
movement of the metal material during its extrusion through the
shoulder.
3. A process as defined in claim 2, and including the step of
accurately sizing the inner smaller cross-sectional periphery,
namely, that of the thickened end, by applying a second, smaller
size punch portion upon the free end of the first mentioned punch
and locating said second punch portion within the shoulder during
the time that the ram pushes the second blank to correspondingly
push the remaining first blank portion through the shoulder.
Description
BACKGROUND OF INVENTION
The invention herein relates to a process for cold forming or
extruding a metal tube having a thickened or inwardly flanged end.
While the process herein may be used to form tubes for a variety of
purposes, it is particularly adaptable in the manufacture of rear
axles for trucks, such as is commonly called a "Salesbury axle." In
such type axles, it is common to forge or machine or both, an
elongated tube having an end portion of reduced outer and inner
diameters and formed with steps or shoulders for connection to
wheel bearings and the like. The main portion of the axle is formed
as a relatively thin wall uniform diameter tube and the opposite
end is formed with an inwardly directed flange or thickened
portion. Such end is normally inserted into a socket formed on a
housing, such as a truck differential housing.
The forming of such a type axle requires a number of forging steps
and then a number of machining steps to provide the accurate sizes
required and also proper surface finishings. Since the axle is made
of one piece of metal, a number of compromises as to the type of
metal selected and the proper heat treating, must be made to
maximize the different strength and other characteristics required
from the opposite ends of the axle.
Hence, the process herein is concerned with the manufacturing of
part of such a type axle, namely, the body or barrel portion with
the thickened end, wherein such an axle may be made in two parts
rather than in one as is conventional, to thereby reduce
manufacturing steps and costs and provide for a better product.
Such process may also be used to produce metal parts which
generally are uniformly tubular in shape with an inwardly extending
flange or thickened portion at one end.
SUMMARY OF INVENTION
The invention herein contemplates forming a uniform cross-section
tube with an inwardly directed flange or thickened portion at one
end, starting with a short, tubular blank which is cold formed or
extruded through a die in a press. The die, mounted upon a press
bed, is formed with an open blank receiving portion, beneath which
is an annular shoulder or extrusion throat with a smaller opening
through which the blank may be extruded. The press ram is provided
with a ram punch member for pressing the blank through the shoulder
and its opening.
The process herein includes first pressing the blank partially
through the extrusion shoulder so that a substantial portion of the
blank is extruded into a uniform, relatively thin wall, tubular
section, leaving an outwardly flanged remaining blank portion in
the die blank receiving part. Then a new blank is placed into the
die and it too is pressed downwardly through the shoulder or die
opening. In so doing, the previous, partially pressed blank is
pushed through the extrusion shoulder. As it goes through, its
thickened outwardly directed flange portion cold flows inwardly to
form an inwardly thickened or flanged portion.
Meanwhile, the new blank is partially extruded and takes the place
of the preceding blank. Then the cycle is repeated by again adding
a new blank, etc. Thus, each new blank acts as if it is part of the
ram punch, making the contact with the preceding blank and
consequently permitting much faster production as compared to a
single blank by blank operation, but also reducing wear and
breakage of the ram punch itself.
The ram punch may be provided with properly sized, smaller
extension members which fit into the blank for sizing the inner
diameters of the blank during the extrusion thereof. Hence, the
finished product can be held to a very accurate tolerance with
respect to its OD and ID, thereby eliminating machining and surface
finishing steps which have been required in the past, in connection
with forming such devices by forging or machining processes.
Where the finished product is to be used as a portion of the above
mentioned Salesbury type axle, the axle portion containing the
various stepped configurations and the like, may be separately
made, as for example, by the process described in my prior U.S.
Pat. No. 3,739,620, issued June 19, 1973 for a Process for Forming
a Flared End Tubular Metal Part.
The two separate pieces, namely, the piece made by the invention of
this application and the second piece may then be welded together
such as by means of inserting the end of one into the other and
spinning one piece relative to the other to generate sufficieint
friction and heat for a good spin formed weld. In this way, a
finished axle or similar device may be made, with the advantage
that the two pieces may be separately made of separate types of
metal and/or separately heat treated to thereby improve the desired
strength and characteristics of each end portion of the finished
part.
These and other objects and advantages of this invention will
become apparent upon reading the following description, of which
the attached drawings form a part.
DESCRIPTION OF DRAWINGS
FIG. 1 is a cross-sectional view of a truck axle made in accordance
with the invention herein.
FIG. 2 is a view similar to FIG. 1 but shows the two parts of the
axle separated.
FIG. 3 illustrates in cross-section, the press apparatus for
carrying out the process herein, with the ram opened and a blank
ready for insertion into the die.
FIG. 4 schematically illustrates the position of the blank in the
die with the ram moved downwardly.
FIGS. 5-8 show successive steps in the process.
DETAILED DESCRIPTION
FIGS. 1 and 2 illustrate a hollow, tubular axle 10, commonly
referred to as a "Salesbury axle" and typically used as the rear
axle of a light truck. Such axles typically are formed with a
reduced or configured end portion 11 having various diametrical
portions for receiving and engaging with wheel or bearing parts,
and an elongated tubular central or barrel portion 12 having an
inwardly flared or inwardly thickened end portion 13. Such axles
have in the past been manufactured in one piece through a variety
of forging and/or machining operations.
The process herein contemplates forming the axle in two separate
pieces, namely, a first piece 15 which encompasses the reduced end
portion 11, and a second piece 16 which includes the barrel portion
12 and the thickened portion 13. Thus, the two pieces are
separately made with the piece 16 made in accordance with the
process of this application and the piece 15 made by some other
process. To asemble the two pieces to make a complete axle, their
respective ends 17 and 18 may be abutted and welded together by a
suitable conventional welding processes.
The process herein contemplates maing the piece 16, or similarly
shaped pieces, from a metal blank 20 which is in the form of a
short, tubular piece of metal, such as steel. As shown in FIG. 3,
the manufacturing equipment includes a die 21 mounted upon a press
bed 22 of a convention press. The die has an upwardly opening blank
reciving chamber or portion 23, beneath which is an annular
extrusion should 24 to provide a central extrusion opening or
throat 25, beneath which is a relieved exit end opening 26. An
opening 17 in the bed or in blocks built up upon the bed provides
space for downward movement of the extrusion.
The die is aligned with a conventional press ram 30, which is
schematically shown as the press itself forms no part of the
invention herein. The ram includes a downwardly extending press ram
punch 31 sized to fit into the die opening 23. The punch also
includes a smaller diameter, downwardly extending sizing punch 32
and a second, even smaller diameter lower sizing punch 33.
With reference to FIGS. 3 through 8, the process herein includes
the following steps: First, as shown in FIG. 3, a blank 20 is
dropped into the die opening 23. The press ram 30 is then lowered,
as shown in FIG. 4, so that the lower end of the ram punch 31
engages the upper end of the blank and the sizing punch 32 extends
through the opening in the center of the blank. Next, as shown in
FIG. 5, the ram is moved downwardly against the press bed, to
extrude the blank partially through the extrusion shoulder and its
opening 25, thereby extruding a relatively thin wall, uniform
diameter wall thickness tube or barrel portion 12.
The downward movement of the ram is stopped before the blank is
completely extruded through the shoulder so as to leave an
enlargemenet or outwardly extending flange portion 35 within the
die opening 23, this portion being the unextruded portion of the
blank.
Next, the ram is retracted, i.e., lifted upwardly, and a new blank
20a, identical to the original blank 20 is dropped into the die
opening 23, as seen in FIG. 6. The new blank is now in end to end
contact with the upper end of the original blank 20, that is the
remaining enlarged portion 35 thereof.
Thereafter, as shown in FIG. 7, the ram is again lowered to press
the blank 20a downwardly into the die, which thereby presses the
original blank through the die opening completely. In this step,
the material which formed the remaining portion of the original
blank, that is the enlargement 35, is forced inwardly, now being
positioned in an inwardly directed enlargement, namely, the
thickened portion 13 whose ID is sized by the sizing punch 33.
Meanwhile, the ram continues moving downwardly, as shown in FIG. 8,
so that the second blank 20a is extruded, in the same way as was
the first blank, and simultaneously pushes the completely extruded
original piece downwardly and out of the die completely. The press
continues downwardly until the second blank assumes the shape and
position of the first blank as is illustrated in FIG. 5 and
thereafter a new blank is inserted as shown in FIG. 6 and the cycle
repeats.
Hence, as can be seen, each blank functions as a portion of the ram
to push the preceding blank during the time it itself is being
extruded. This permits rapid operation, as well as preserving the
press equipment and die against much of the normal wear which would
be encountered in a one-by-one blank pressing operation.
Essentially, the process herein is carried out with the metal being
cold. Actually, it is preferable to heat the metal so as to warm it
to a point below its metallurgical transition points to thus permit
easier flow of the metal under pressure and thereby reduce the
required ram pressure. Thus, by cold forming, it is meant that the
blanks are either at room temperature or at relatively low
temperatures, i.e., below transition points.
Although the figures illustrate the extrusion of a tube of circular
outer and inner diameters, the shape in cross-section of the tube
may be varied. In addition, it is possible in this process to form
inner or outer surface configurations on the tube, such as
longitudinally extending gear teeth, by suitably profiling either
the shoulder throat or opening 25 or the surfaces of the sizing
punches 32 and 33.
* * * * *