Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PRODUCTION OF THREADED METAL RODS_FûR MAKING U-BOLTS
Background of The Invention
In the manufacture of large steel U-bolts of the type,
for example, used to secure a semi-trailer body to a wheel supported
S frame or to secure a leaf spring to a wheel supported axle, it is
common to cut a long steel rod having a diameter, for example, between
3/8 inch and l-l/4 inches into rod sections or shorter rods each of
which is threaded along opposite end portions while the rod remains
straight. The threaded straight rods are then successively inserted
into a hydraulically or power operated rod bending machine which bends
or cold-forms each rod around a U-shaped mandrel to produce a U-bolt.
In order to position each rod within the bending machine,
the operator may use a tape measure to position the rod so that the
mid-point of the rod is aligned with the center of the mandrel. This
measuring operation requ7res significant time. Some bending machines
are also equipped with an adjustable stop which is used for locating
one end of each rod to position the rod properly within the bending
; machine. When rods of dlfferent lengths are successively formed into
U-bolts, it is necessary to adjust the end stop according to the length
of each rod. Sometimes it is necessary to adjust the end stop frequently
since the rods are commonly bent in sets of two or four rods, and
each set may have a different length.
It has been found that as a result of a machine operator
making an inaccurate measurement of the length of a rod or an incorrect
25: adjustment of the end stop, a number of straight rods are formed into
U-bolts without having the center point of the straight rod aligned
precisely with the center plane of the rod bending machine. As a
result, the U-bolts are formed with one leg longer than the other,
and frequently, the improperly bent U-bolts cannot be used and must
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~ 30 be scrapped since the bolts cannot be restraightened and reformed.
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Summary of The Invention
The present invention is directed to the production of
metal U-bolts and provides for a more efficient and economical method
of producing U-bolts by substantially reducing the scrap rate of incorrect-
S ly formed or bent U-bolts and significantly reducing the bending t7me.
The method of the invention eliminates the need for measuring each
straight threaded rod before bending it into a U-bolt or eliminates
the need for adjusting an end stop for each straight rod according
to the length of the rod.
In general these advantages are provided in accordance
with one embodiment of the invention by permanently marking each straight
threaded rod to indicate the longitudinal center point or radial center
plane of the rod. The marking or mark on each rod provides the rod
with an easily visable indTcator of the radially extending center
plane of the rod and the mark is simply aligned with a mark located
on the center of the mandrel of the rod bending machine prior to
bending the straight threaded rod into a U-bolt.
Other features and advantages of the Invention will be
apparent from the following descrip~70n the accompanying drawing
and the appended claims.
Brief Description of The Drawing
FIG. 1 is a perspective view of a straight metal rod having
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opposite threaded end portions and a center portion with a permanent
mark indicating the long1tudinal center of the rod in accordance with
the Invention;
FIG. 2 is an enlarged fragmentary perspective view of the
center portion of the rod shown in FIG. 1 and illustrating the permanent
mark for indicating the center plane of the rod;
FIG-~3 is a diagrammatic view of a device for applying
;30 ~ ~ the~permanent center indicating mark on the rod shown in FIGS. 1 and 2;
FIG 4 ls an elevational view of one form of rod bending machine
for producing a U-bolt;
FIG. 5 is a side view of a U-bolt formed with the rod shown
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in FIG. 1;
FIG~ 6 is a perspective view similar to FI~. 1 and showing
a threaded rod having another form of center indicating mark;
FIG. 7 is a diagrammatic end view of a machine f`or marking
a supply of threaded rods;
FIG. 8 is 8 diagrammatic perspective view of the marking
operation shown in FIG. 7;
FIG. 9 is a fragmentary perspective view of a threaded rod and
showing the marking of the rod in accordance with a modification of the
invention; and
FIG. 10 is a diagrammatic view similar to FIG. 7 and illustrating
the marking of the rod shown in FIG. 9.
Description of the Preferred Embodiments
Referring to FIG. 1, a cylindrical metal or steel rod 10
has a smooth cylindrical outer surface forming a center portion 12 between
oposite threaded end portions 14. As mentioned above, the threaded
metal rods are commonly manufactured in a wide range of diarneters, for
example, from 3/8 inch to 1-1/4 inches and in different steel compositions
according to the uses or applications of the rods after they are bent
2û or cold-formed into U-bolts such as the U-bolt 15 illustrated in FIG. 5.
In accordance with the present invention, the rod 1û has
a diameter of at least one half inch and a visual indicating mark 20
which identifies the longitudinal center of the rod 10 or the radially
extending center plane. As shown in FIG. 2, one type of center indicating
mark 20 is formed by two axially spaced and circurnfersntially extending
knurls 22 which are embossed or impre8sed into the outer cylindrical
surface of the rod 10. An identification or code number 24 extends
circumferentially between the knurls 22 and lies within the radially
extending center plane of the rod 10. Preferably, the number 24 identifies
the particular steel used for forming the straight rod 10. However,
the circumferentially extending number 24 may also identify other information,
such as the diameter and length of the rod 10 ur the part number for
the final U-bolt 15 or the date of manufacture.
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The rod center indicating mark 20 is preferably applied
to the rod before the end portions are threaded and after the rod
is cut to a predetermined length from a longer steel rod. A supply
of the rods 10 successively receive the mark 20 within a machine or
power operated device wherein each of the rods 10 is rotatably supported
by a set of cradle forming rollers 26 (FIG. 3) mounted on frame members
27. An elongated metal dye 30 has two parallel rows of parallel teeth
31 and is moved linearly by a double acting fluid cylinder 32 into
tangential engagement with the rod 10 so that the teeth 31 form the
circumferentially extending knurls 22. T,He'dye 30 also carries a
row of outwardly projecting characters (not shown) located between
the rows of teeth 31, and the characters form or impress the code
number 24 within the outer surface of the rod 10. A series of backup
rollers 34 are supported in a row by a frame member 36 and function to
gu7de the dye 30 so that the teeth 31 and the outwardly projecting
characters are pressed into the outer surface of the rod 10 to deform
: or emboss the metal.
After a supply of rods 10 are successively embossed with
corresponding marks 20,and the outer end portions of the rods are
threaded to form the threaded end port70ns 14, the rods are ready
to be successlvely cold-formed or bent into U-bolts. One form of
'~ rod bendlng 0achlne 40 Is Illustrated In FIG. 4. The bending machine
~' 40 Includes a base plate or beam 42 which supports an interchangeable
steel die or'mandrel'44 having a U-shaped rod locating groove 46.
;~ 25 The'mandrel 44, or an adJacent movable bar clamping block, has a mark
' or indicator 48 which identifiès the center plane of the bending machine
40 or bending operatTon. '
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~ A carriage 52 is supported by the'base plate 42 for recip-
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~ rocating movement~In response to actuat'ion of a double acting
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fluid cylinder 54. The carriage 52 includes a set of lever arms 56 which
are pivotally supported by corresponding pivot pins 57. The lower end
portions of the arms 56 carry a corresponding pair of grooved forming
rollers 5g, and the upper end portions of the arms 56 support pivotal
nuts 62 which receive oppositely threaded end portions of a rotatable
adjusting screw 64. A set of crank arms 66 are secured to opposite ends
of the screw 64 and provide for adjusting or pivoting the arms 56 and
adjusting the spacing between the forming rollers 59 according to the
size or width of the selected mandrel 44.
As illustrated in FIG. 4, a supply of the rods lO shown in
FIG. l are successively inserted into the bending machine 40 where each
rod lO rests on the grooved mandrel 44. The code number 24 of the mark
20 is aligned with the center indicator 48 on the mandrel 44, as shown
in FIG. 4. The cylinder 54 is then actuated to move the carriage 52 towards
the mandrel 44 so that the rollers 59 form or bend the rod around the
mandrel 44 to form the U-bolt l5. After the carriage 52 is retracted,
the U-bolt is removed from the mandrel 44, and the next straight rod lO
15 Inserted Into the bending machine 40.
FIG. 6 illustrates another cyltndrical metal or steel rod 80
which is constructed substantially the same as the steel rod lO and has
opposite threaded end portions 82. The rod 80 has a smooth outer surface
83 which is provided with a center indicating mark 84 in the form of an
ink stripe extending circumferentially completely around the rod. The
ink stripe 84 Is applied to the rod after the cylindrical outer surface
83 is cleaned, and the color of the ink provides a distincttve contrast
with the color of the rod 80, such as, for example, a yellow ink stripe
on the dark gray color of the steel rod.
~ enter 7ndicating marks 84 are successively applied to a supply
of rods 80 with a marking machine having a marking head 85 which is generally
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illustrated in FIG. 7. The rods 80 are supplied to the marking head 85
on an inclined ramp 88 and are successively transferred by a transfer
mechanism (not shown) to a cradle support formed by a set of axially
spaced pairs of freely rotating cradle rollers 92. The rollers 92 are
supported by a carriage 95 which moves vertically to bring each rod 80
into contact with a printing wheel 96 forming part of ~he marking head 85
of the marking machine. The printing wheel 96 receives ink from a transfer
wheel 98 which in turn receives ink from an applicating wheel 102
projecting into an ink supply reservoir 104.
The printing wheel 96 and the wheels 98 and 102 are driven
by a drive 106 such as an air motor and gear reducer unit. As each rod
8~ is moved into contact with the printing wheel 96 by upward movement
of the carriage 95 the driven wheel 96 rotates the rod 80 supported by
the cradle rollers 92 while also applying or printing the circumferentially
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extending stripe or center indicating mark 84 on the rod. After the print-
lng operation the carriage 94 is lowered and the printed rod 80 is
transferred laterally from the cradle rollers 92 by the transfer mechanism
to a ramp 110 which collects the printed rods 80 each havtng a center
indicating mark 84.
In place of supporting the cradle rollers 92 by a vertical
movable carriage 94 the cradle rollers 92 may be supported in a fixed
position and the marking head 85 including printlng wheels 96, 98 and
102 and reservoir 104 may be supported for vertical or pivotal movement
so that the power driven printing wheel 96 moves downwardly into engage-
ment with each rod 80 after it is transferred to the cradle rollers 92.
,
In order for the marking machine to accommodate threaded rods of various
dIfferent lengths the rods may be guided down the supply ramp 88 by a
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pair of ad3ustable end guide plates and the end guide plates and the
corresponding pair of end cradle rollers 92 may be adjustable axially
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relative to the center pair of cradle rollers 92 and the marking head
85. As an alternative, the marking machine may be constructed so that
one pair of end cradle rollers 92 is fixed and the opposite end pair
of cradle rollers 92 is adjustable axially according to the length of
the threaded rods being supplied. In this construction, the supports
for the center pair of cradle rollers 92 and for the marking or printing
head 85 are supported for axial movement equal to one half of the axial
movement of the movable end pair of cradle rollers 92. This relative
adjustability is provided by the use of separate lead screws for each
of the movable components, with the lead screws being connected by an
endless chain for simultaneous rotation at a 2 to 1 ratio.
Referring to FIGS. 9 and 10 which illustrate another embodiment
of the invention, a cylindrical metal or steel rod 120 has a center
portion 122 with a smooth outer surface and opposite threaded end portions
124. The longitudinal center of the rod 120 is marked by a pressure
sensitive adhesive label 125 which is wrapped around the rod 120 with
overlapping end portions. The label 125 is printed with a longitudinally
extending line 128 of color contrasting ink and forms a circumferentially
extending Atripe or mark on the rod 120 within a radially extending
center plane. The label 125 is also repetitively printed with other
information which may be in the form of trademarks 132 and 134. The
thickness of the label 125 is exaggerated in FIG. 9 for purpose of
illustration.
As shown in FIG. 10, a succession of preprinted and die-cut
labels 125 are releasably carried by a carrier strip 136, and the combined
strip and labels are supplied in a roll 138. The pressure sensitive
labels 125 are successively attached to the center portions 122 of the
~- rods 120 with the aid of a transfer mechanism as described above in
connection with FIG. 7.
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After each rod 120 is elevated to the resilient outer surface
of an applicator wheel 142 driven by a motor 144, a label 125 is peeled
or separated from the carrier strip 136 around the peel edge of a stripping
blade or member 146. The carrier strip 136 is pulled around the member
146 by a rewind core or spool 148 driven by a motor 150 in timed relation
with the vertical movement of the transfer carriage 95. The applicator
wheel 142 is also rotated in timed relation with the rewind spool 148
so that each label 125 is pressed into firm contact with the outer cylin-
drical surface of a rod 120 as the label is peeled from the carrier
strip 136 and wrapped onto the rod.
From the drawing and the above description, it is apparent
that large diameter threaded rods produced in accordance with the invention
for making heavy duty U-bolts, provide desirable features and advantages.
As a primary advantage, the mark identifylng the longitudinal center
of each rod provides for quickly and accurately locating each rod within
~i a U-bolt bending machine and thereby provides for more efficiently producing
U-bolts. The center indicating mark on each rod also eliminates the
problem of inaccurately measuring each rod to locate the center of the
rod and the problem of adjusting a stop for positioning one end of each
rod within the bending machine, thereby significantly reducing the pro-
duction of defective or scrap U-bolts.
Another advantage is provided by extending the rod center
- indlcator or mark around the circumference of the rod, such as the mark
20 or 84 or 128, 80 that each rod may be guickly located within the
bending machine without reguiring that the rod be rotated to locate
~ ~ a ccnter identifying mark. In addition, the color contrasting ink forming
-~ ; the center indicating mark 84 or 128, provides for a permanent identiFi-
cation which may not be inadvertently removed. As mentioned above,
the rod center i~dcntifying mark may also be used to identify the heat
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number for the steel forming the rod and/or to provide other information
such as the manufacturer of the steel or date of marking.
While the methods of producing threaded metal rods for forming
U-bolts and the construction of the rods herein described constitute
preferred embodiments of the invention, it is to be understood that
the invention is not limited to these precise methods and rod constructions,
and that changes may be made therein without departing from the scope
and spirit of the invention as defined in the appended claims. For
example, each rod may be provided with a center indicating mark by stamping
or marking only a center portion of the rod surface in place of the
mark 20 or 84 or 128 which extends around the circumference of the rod.
The invention having thus been described, the following is
claimed:
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