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Патент USA US3039199

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June 19, 1962
2 Sheets-Sheet 1
Filed Dec. 17, 1956
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June 19, 1962
2 Sheets-Sheet 2
Filed Dec. 17, 1956
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United States Patent 0 ' "ice
_ Patented June 19, 1962
FIGURE 7 is a greatly enlarged diagrammatic view
showing the way in which the strip is formed around a
post and the way in which the ?ange is held during the
Frank J. Kennedy, Pittsburgh, Pa., assignor, by mesne as
signments, to H. K. Porter Company, Inc., Pittsburgh,
bending of the strip around the post;
FIGURE 8 is a sectional View, on a reduced scale
from FIGURE 7, showing the way in which the edges
Pa., a corporation of Delaware
of the strip are secured together after removal from the
apparatus shown in FIGURE 1 ; and
FIGURE 9 is a sectional view showing the completed
This invention relates to the thread protectors which 10 thread protector, but with a modi?ed type of seam from
that shown in FIGURE 8.
are screwed over the ends of pipes to protect the threads
Filed Dec. 17, 1956, Ser. No. 628,762
6 Claims. (Cl. 29-534)
in shipment, storage, and subsequent handling prior to
Pipes are commonly sold in standard lengths and with
both ends threaded. A coupling is ordinarily supplied
The thread protectors of this invention are preferably
made from strip stock which is supplied in a reel 11.
actual use.
The strip material is metal and preferably hot rolled
15 steel, this being a satisfactory and economical material
for the thread protector. Eighteen carbon steel has been
found to be particularly satisfactory but this is described
merely as an illustration, and the invention is not limited
with each pipe and this coupling is screwed over the
threads at one end of the pipe. Protection is needed for
the threads on the other end, and it is usual to have some
to such steel, and may even use other kinds of metal such
as strip aluminum. 'It is, of course, necessary that the
kind of inexpensive ?tting which is used only for the
purpose of protecting the threads prior to the time that
material be malleable. The height and thickness of the
strip depends upon the size of the thread protector to
For moderate and large sizes of pipe, thread protectors
be made and upon the depth of threads and mechanical
of suf?cient strength to protect the threads adequately
strength desired in the ?nal product.
have been of such high cost that economic considerations
The metal strip as it comes from the reel 11 is indi
required that they be returned to the pipe mill for reuse. 25
the pipe is brought to the location Where it is to be used.
cated by the reference character '12. It is advanced
through the apparatus with .a step-by-step movement.
Any suitable apparatus for this purpose can be used. The
drawing shows a clutch 14 in a slide block 15 which
This has not always been satisfactory because it entails
the inconvenience and cost of gathering and shipping
discarded protectors and the expense of reconditioning
those damaged in service.
runs along a guideway 16.
It is an object of this invention to provide a method
of making thread protectors from less expensive stock
way 16 by a cam 18 having a groove therein.
and at greatly reduced labor cost. The thread protectors
groove of the cam 18.
duced cost that when made of light gage stock they can
Another object of the invention is to provide an im
proved method for making thread protectors from ?at
stock and with a minimum of hand labor. The method
A cam
follower 20, extending from the clutch 14, ?ts into the
made in accordance with this invention are of such re
be scrapped after one use.
The clutch 14 and slide
block 15 are reciprocated back and forth along the guide
The cam 18 is supported by an axle 22 extending
through a bearing 24. The axle 22 is rotated by a worm
wheel 26 driven by a worm 28 on a main drive shaft 30.
A motor 32 rotates the main drive shaft 30. The feed
mechanism described is merely representative of step-by
cutting, shaping and bending the stock to make the 40 step mechanism for advancing the strip 12 successively
by uniform strokes.
The strip 12 is fed to a ?rst work station designated
Another object is to provide a thread protector of such
generally by the reference character 35. At this work
construction that it can be made on a multi-slide machine
‘station 35, a punch 36 is reciprocated back and forth
and by the method of this invention.
Other objects, features, and advantages of the invention 45 in a bearing 37 by a groove cam 38 on a drive shaft 39.
preferably includes the use of a multi-slide machine for
will appear or be pointed out as the description proceeds.
This drive shaft is driven by a worm wheel 26 meshing
with a worm 28 on the main drive shaft 30. There is
In the drawing, forming a part hereof, in which like
a die 42 on the other side of the strip from the punch
reference characters indicate corresponding parts in all
36 and the die 42 has a recessed face 44 for receiving the
the views;
FIGURE 1 is a diagrammatic top view, mostly in sec 50 punch 36. The cam 38 operates in timed relation with
the feed mechanism so that the punch 36 advances against
tion, showing a multislide machine equipped for perform
the strip 12 during a portion of the cycle when the strip
ing most of the steps for making thread Protectors in
is stationary.
accordance with this invention;
In the preferred operation of the invention, the punch
FIGURE 2 is greatly enlarged side view showing the
strip after it has been punched at the ?rst work station 55 36 notches the strip 12 vas shown in FIGURE 2. Notches
47 and 48 are punched in the upper and lower edges, re
of the apparatus shown in FIGURE 1;
FIGURE 3 is an enlarged, transverse sectional view
spectively, of the strip 12; and an opening 50 is punched
showing the position of the strip and adjacent parts at
through the mid portion of the strip. This opening 50 is
the second work station of the apparatus shown in FIG
shaped so that a dove tail tab 52 is left at one side of
URE 1 before the die has closed;
60 the opening 50‘ and a dove tail cut-out 54 is left on the
FIGURE 4 is a view corresponding to FIGURE 3 but
other side of the opening. The two portions of the strip
showing the shape of the strip and the position of the
that are left between the opening 50 and the top and bot
parts after the die has closed;
tom notches 47 and 48 are for the purpose of keeping the
FIGURE 5 is an enlarged, transverse sectional view
showing the strip and adjacent parts of the apparatus 65 strip in one piece during its travel through subsequent
‘work stations. This permits better control of the strip
at the third work station and before the die has closed;
and also permits it to be effectively fed through all work
FIGURE 6 is a view corresponding to FIGURE 5 but
stations by a single feed mechanism. At the end of the
showing the shape of the strip and the position of the
work stations these sections of strip between the opening
:parts after the die has closed;
50 and the top and bottom notches 47 and 48 are re
in the ?nished thread protector. It is the throat which is
threaded in the ?nal product, and this makes the c0n~
stant diameter of the middle portion of the formed thread
moved, as will be more fully explained.
One step of the feed mechanism ‘advances a cut-out
portion of the strip from the punch 36 to the ‘left-hand end
of a second Work station 55. The next operation of the
feed mechanism advances the length of strip‘ behind this
cut-out into the work station 55, the length of the work
station being equal to the length of the feed stroke which
is in turn equal to the length of strip to be used for mak
ing one thread protector.
protector desirable.
The next step of advancement of the strip 12 carries
the blank in the work station 76 to a location where the
forward end of the blank is between a punch 97 on one
side of the strip and a die 98 on the other side of the
strip. The punch 97 is stationary, being connected with
10 a ?xed frame 100; and the die 598 is moved toward and
At the work station 55 there is a die consisting of a
from the punch to displace the strip 12 against the
relatively ?xed element 57 and a movable element 58.
punch. This movement of the strip causes the punch
The movable element is attached to and guided by dowels
to sever the strip by punching out the two remaining parts
60 which slide in bearings in a ?xed frame 62. The mov
of the strip above and below the opening 501 (FIG
able die element 58 is advanced against the relatively 15 URE 2).
?xed die element 57 by a cam 64. There are springs 66
The die 98 slides in bearings in a ?xed frame ‘102. A
for rbringing the movable die element 58 back as the cam
cam 104 advances the die 98, and a spring 186 retracts
64 continues to rotate. The cam 64 is secured to a shaft
the die. The cam 104 is rotated by a shaft 108, and the
68 rotated by a worm wheel 26 which meshes with a
shaft 108 is rotated by a worm wheel 26 meshing with a
worm 28 on the main drive shaft 30. The cam 64 ad
worm 28 on the main drive shaft 30'.
vances the movable die element 58 to force the strip
The blank which is beyond the punch 97, and which
against the relatively ?xed vdie element 57 at the time in
is severed from the strip 12 by this ?nal punching opera
the cycle when the strip 12 is stationary.
tion, is indicated by the reference character 12'. A post
FIGURE 3 shows the strip 12 against the die element
112 is located at a mid point between the ends of the
57 and held against upward movement by a guide 70 at 25 blank 12’ and in contact with one side of the blank.
tached to the die element ‘57. The movable die element 58
has a springdloaded hold-down 72 and a forming punch
There is a bending tool 114 on the other side of the blank,
and this tool 114 has a recessed face 116 shaped to bend
the blank 12' around the post 112 into the dotted line
relatively ?xed die element 57, the hold down 72 comes
position shown in FIGURE 1.
into contact with the strip 12 ?rst and holds the strip 30
The bending tool 114 slides in a guide way 118, and
?rmly in position. ' The form punch 74 advances into
is advanced by a cam 120 on a shaft 122 with a worm
contact with the lower part of the strip 12 and forms it
wheel 126. This worm wheel is rotated by a worm 28
to the contour of the die elements 57 and 58, ‘as shown
on the main drive shaft 30. The bending tool 114 is
in FIGURE 4.
retracted by springs 130 attached at one end to lugs 132
Thus the strip 12, after operation of the die at the 35 on the bending tool 114 and at their other ends to ?xed
As the movable die element 58 moves toward the
second work station, has its lower end portion bent in
wardly to form a ?ange 75. This ?ange 75 extends along
the full length of each part of the strip which is to be
anchors 134.
with the ?ange 75 and the portion of the strip 12 just
albove the ?ange 75. The movable die element 78 also
tab 52 (FIGURE 2) is made slightly oversize with respect
has a formed punch 92 with a contour complementary to
FIGURE 7 shows the way in which the bending tool
114 exerts pressure against the blank 12' to bend it around
After the blank 12’ has been bent around the post into
the dotted line position shown in FIGURE 1, a second
used to make a thread protector, that is, the ?ange 75 ex
cam-operated tool 140 is moved into contact with the
40 left hand portion of the blank 12’ to bend the blank
tends for the full length of each blank.
Beyond the second work station 55 (FIGURE 1) there
around the upper left hand quadrant of the post 112.
is a third work station 76. This work station includes a
This bending tool 140 slides in a bearing 142 of a ?xed
relatively ?xed die element 77 and a movable die element
78 vsupported by dowels 80 which slide in bearings in a
A third cam-operated bending ‘tool 145 slides in a bear
?xed frame 82.
45 ing 146 and into contact with the right hand portion of
The movable die element 78 is advanced toward the
the blank 12' to bend the blank around the upper right
relatively ?xed die element 77 by a cam 84, and the mov
hand quadrant of the post 112. A fourth bending tool
able die element 78 is retracted by springs 86. The cam
150 slides in a bearing 152, and is moved into contact
'84 is secured to a drive shaft 88 driven by a worm wheel
with the confronting end portions of the blank between
26 meshing with a worm 28 on the main drive shaft 30. 50 the tools 140 and 145. The radial pressure from the
FIGURE 5 shows the contour of the die elements 77
tool 150 forces the dove tail projection 52 (FIGURE 2)
and 78. The relatively ?xed die element 77 is shaped
into the dove tail groove 54 and thus secures the opposite
so that the ?ange 75 extends'under a clearance provided
ends of the blank 12’ together. When using a tab and
for the purpose. The movable die element 78‘ has a
dove tail groove to connect the ends of the blank, a sub
spring-loaded hold-down 90 which is shaped to contact 55 stantial pressure by the tool 150 is necessary because the
that of the relatively ?xed die element 77. After the
to the dove tail groove 54 in order to obtain a force ?t.
spring-loaded hold-down 90 has gripped the lower portion 60 the post 112. The tool 114 has a bottom lip 156 which
of the strip 12, further advancing movement of the mov~
holds the ?ange 75 to prevent it from straightening out
able die element 78 causes the formed punch 92 to deform
the strip 12 to the contours of the die element 77 as
shown in FIGURE 6.
as the blank 112 is bent around the post. Because of
the stiffness of the metal of the blank 12', it is not neces
sary to shape the post 112 to ?t the convex surface of
Thus when the strip 12 leaves the third work station, 65 the inside of the blank. The tool 114 has a center por
the portion of the strip above the ?ange 75 has a cross
tion which contacts with the mid portion of the blank
section which may be described as “concavo‘dconvex.”
12' to force it against the post 112 with su?icient pressure
In the construction shown, the cross section of the surface
to give the blank 12' a curvature equal to the outside
of the strip is bounded by straight lines which meet in
diameter of the post 112.
angular relation but the exact shape is not critical and 70 It is not necessary to have the post 112 undersize to
the concave-convex cross section may be generally curved
allow for spring back of the blank 12' because when the
instead of having the straight angular relation illustrated;
ends of the blank are fastened together by the dove tail
but it is desirable to have the intermediate portion of the
tab and groove, as previously explained, the blank 12’
strip generally straight so as to obtain a substantially uni
is held against any expansion.
form ‘diameter for a portion of the length of the “throat” 75
The post 112 can be shaped to ?t the inside surface
contour of the blank 12’ if desired, but it is preferred
to have the post 112 with sidewalls that taper slightly to
a smaller diameter at the lower end and without any
extension of the post into the clearance with the blank
12’ just above the ?ange 75. By having the straight
taper, as shown in FIGURE 7, the formed thread pro
tector can be stripped from the post 112 as soon as the
tools are Withdrawn, by a stripper ring 160 which is
cutting it from the strip to form a separated blank in
the ?nal bending station, bending each successive blank
in said ?nal bending station in a direction with the ?ange
extending inward, and holding the ?ange in its angular
relation to the rest of the strip during said bending, and
simultaneously with the operations at the other regions
on the uncut strip, continuing the bending of the blank to
a substantially circular shape with the opposite ends
pushed downwardly by operating links 162 when the
of the blank confronting one another at a seam of the
desired a continuous weld can be made along the whole
length of the seam 116, or the seam edges can be brazed
of a continuous mechanical process‘
time comes to strip the formed thread protector from 10 thread protector, the bending being in a direction to leave
the concove surface of the blank on the inside of the curve
the post 112.
to form the throat for the thread protector, and the bend
FIGURE 8 shows the thread protector, which will be
ing at the ?nal bending station being performed by
designated by the same reference character 12' as used
bringing forces against the blank at successive locations
for the blank, after the thread protector has been re
with the successive locations further along the blank
moved from the post. The confronting end faces of the
toward the ends thereof, the forming, cutting and bend
metal form a seam 166, and the edges of this seam are
ing being performed at adjacent work regions and as part
permanently connected together by spot welds 168. If
2. The method of making thread protectors as de
scribed -in claim 1 and in which the strip is cut to form
or otherwise bonded together. If the equipment is
ends for the blanks prior to any other operations on the
designed for the purpose, the spot welds 168 can be made
strip, but connections are left across the cuts and between
while the thread protector 12' is on the post around which
the ends of successive blanks so as to maintain the con
it is ‘formed, but generally the spot welding is done after
tinuity of the strip during subsequent operations, and the
removing the thread protector from the post.
The ?nal ‘operation in the manufacture of the thread 25 connecting portions are ?nally cut from the strip after
the forming operations on the strip and before the bend
protector is the chasing of threads 172 (FIGURE 9) in
ing of a blank to circular shape.
the inside surface of the throat, This thread corresponds
3. The method of making thread protectors as de
to the thread of the pipe on which the protector 12' is
scribed in claim 1, and in which the opposite ends of the
intended to be used. FIGURE 9 shows the pipe in phan
formed blank are connected together along at least a por
tom and the pipe is designated by the reference character
tion of the length of the seam between said ends, and the
175. It will be noted that the ?ange 75 extends inwardly
inside surface of the thread protector is then threaded
far enough to cover the end face of the pipe 175.
with threads of a size to screw on the pipe with which the
thread protector is intended to be used.
4. The method of making thread protectors as de
and may be brazed while on the forming post, but prefer 35
scribed in claim 1 and in which the strip is advanced
ably after removal from the post. If the seam edges
with a step-by-step feed and the ?ange is formed by the
spread after removal of the bending tools and the seam
application of pressure to the full length of a blank si
is not brazed until after removal from the post around
multaneously and while the strip is stationary, and after
which it is formed, then it is necessary to insert the thread
protector in a clamp which brings the seam edges together 40 the blank is advanced another step by the step-by-step
feed, the concave-convex cross section is imparted to the
again for brazing, welding or otherwise bonding them.
strip by force applied simultaneously to the full length of
The dove tail tab 52 and cut-out 54 of the preferred
FIGURE 9 shows the thread protector with a seam 177
having no dove tail connection. This seam 177 is brazed
the blank while the blank is stationary between feeding
construction has the outstanding advantage of providing a
steps, and holding forces are applied to the ?ange in
simple fastening for holding the seam together, and a
fastening which can be made and connected automatically 45 both a longitudinal and radial direction to prevent the
?ange from straightening out during the bending of the
as a part of the automatic cutting, shaping and bending
of the strip to form the thread protector as illustrated dia
metal of the blank to a circular shape.
5. The method of making a thread protector having a
grammatically in FIGURES 1-7.
?aring entrance with a smooth inside surface for receiv
The preferred construction has been illustrated and
described, but changes and modi?cations can be made 50 ing the end of the pipe on which the thread protector is
to be used, and with a throat at the inner end of the
diverging entrance, threads on the throat for screwing
over the pipe and an enlarged diameter portion beyond
the throat with clearance from the ends of the threads
of the pipe on which the protector is screwed, which
method comprises feeding a ?at strip of hot-rolled steel
which has a ?ared entrance at one end, an inwardly ex
to a ?rst work station, cutting the strip at the ?rst station
tending ?ange at the other end, and a throat intermedi
to provide a dove-tail projection and a complementary
ate the ends, which method comprises feeding a continu
dove tail groove on opposite sides of the cut and with the
ous length of ?at strip in successive steps each of which
is equal to the length of strip required to make a pro 60 cut discontinuous along the height of the strip so that
successive blanks produced by cuts at the different regions
tector, advancing different portions of the strip by one
along the length of the strip are connected together in
of said feeding steps in a substantially straight line to and
end-to-end relation, advancing the strip with a step-by
through successive work regions and bringing a new
step motion in successive steps each of which is equal to
length of the strip to a ?rst work region, operating on
di?erent portions of the strip while in said straight line 65 the length of strip required to make a protector, applying
reciprocating pressure to the strip between feeding steps
and at the different work regions to form a ?ange ex
and along the full length of a blank to form a ?ange
tending lengthwise along one edge of the strip at one
along the entire length of one longitudinal edge of the
Working region, and to form a portion of the remaining
and some features can be used in different combinations
without departing from the invention as de?ned in the
What is claimed is:
1. The method of making thread protectors, each of
height of the strip with a concavo-convex cross section
blank, forming the strip at another work station by apply
extending lengthwise of the strip, advancing an end por
tion of the strip to a ?nal bending station into positions
to be operated upon by tools at said ?nal bending sta
tion and while said end portion with its ?anged edge and
ing force which bends the strip above the ?ange to a
concavo-convex cross section along the entire length of
the blank, cutting the connection between successive
blanks after the forming operations, bending each blank
concavo-convex cross section remains attached to the rest
as it is severed from the strip to a circular shape and hold
of the strip, and with said end portion so positioned,
ing the ?ange in its angular relation to the rest of the
strip during said bending, continuing the bending until
the opposite ends of the blank confront one another along
a seam, the bending being performed by maintaining
resisting force against the inside of the bend and by
applying radial forces inwardly at different angular loca 5
tions successively around the circular contour to Which
the blank is bent, bonding the seam edge together along
at least a portion of the length of the seam, and then
threading the throat of the protector to ?t the threads
of a pipe with which the protector is intended to be used. 10
6. The method of making a thread protector as de
scribed in claim 5 and in which the ends of the blank
on opposite sides of the seam are locked together as a
part of the bending operation and the seam is then per
manently bonded by spot Welding at spaced regions along 15
its length.
References Cited in the ?le of this patent
Blakey ______________ __ Jan. 27,
Schweinert et a1. ______ __ Apr. 30, 1907
Cable _______________ __ Aug. 15,
Shrum et a1. _________ __ Aug. 23,
Klocke ______________ __ Dec. 30,
Engstrom ____________ __ Nov. 26,
Keller _______________ __ Aug. 9,
Kennedy _____________ __ Mar. 6,
Clark ________________ -_ Sept. 9,
Peter et al. ___________ __ Feb. 22,
Houck ______________ _.. Sept. 11,
Ellzey _______________ .._. Mar. 26,
Borton _______________ __ Dec. 2,
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