U.S. patent application number 09/848837 was filed with the patent office on 2001-09-06 for apparatus for forming tapered spiral tubes.
Invention is credited to Davis, Paul K., Marquis, James A., Miller, Robert E..
Application Number | 20010018839 09/848837 |
Document ID | / |
Family ID | 21758666 |
Filed Date | 2001-09-06 |
United States Patent
Application |
20010018839 |
Kind Code |
A1 |
Miller, Robert E. ; et
al. |
September 6, 2001 |
Apparatus for forming tapered spiral tubes
Abstract
Apparatus for forming tapered spiral tubes from strips, is
disclosed. The apparatus comprises a spiral tube forming system for
forming a strip into a spiral tube; a strip infeed system adapted
for feeding a strip to the pipe forming system; and
computer-controlled means for continuously varying the angular
orientation of the tube forming system relative to the strip infeed
system to selectively vary the diameter of the forming tube. The
selective variation of the diameter includes linearly tapered and
curved profiles, as well as constant (unchanging) diameter profiles
and combinations thereof.
Inventors: |
Miller, Robert E.;
(Lafayette, CA) ; Marquis, James A.; (Lafayette,
CA) ; Davis, Paul K.; (Auburn, CA) |
Correspondence
Address: |
LAW OFFICES OF PHILIP DALTON
236 WEST PORTAL AVE., NO. 15
SAN FRANCISCO
CA
94127-1423
US
|
Family ID: |
21758666 |
Appl. No.: |
09/848837 |
Filed: |
May 3, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09848837 |
May 3, 2001 |
|
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09013171 |
Jan 27, 1998 |
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Current U.S.
Class: |
72/49 |
Current CPC
Class: |
B21C 37/124 20130101;
B21C 37/128 20130101; B21C 37/12 20130101; B21C 37/126
20130101 |
Class at
Publication: |
72/49 |
International
Class: |
B21C 037/12 |
Claims
What is claimed is:
1. Apparatus for forming tapered spiral tubes from strips,
comprising: a spiral tube forming system for forming a strip into a
spiral tube; a strip infeed system adapted for feeding a strip to
the tube forming system; the tube forming system and the strip
infeed system being adapted for pivotal movement relative to one
another to vary the angle therebetween; a motor drive system for
effecting said pivotal movement between the strip infeed system and
the tube forming system; and a computer system operatively
connected to the motor drive system for operating the motor drive
system to selectively vary the diameter of the forming tube.
2. Apparatus for forming tapered spiral tubes from metal strips,
comprising: a spiral tube forming system for forming a metal strip
into a spiral tube; a strip infeed system adapted for feeding a
metal strip to the tube forming system and further adapted for
pivotal movement relative to the tube forming system to vary the
angle therebetween; a motor drive system operatively connected to
the strip infeed system for effecting said pivotal movement; and a
computer system operatively connected to the motor drive system for
operating the motor drive system to selectively vary the diameter
of the forming tube.
3. Apparatus for forming tapered spiral tubes from metal strips,
comprising: a tube forming system for forming a metal strip into a
spiral tube, said tube forming system comprising cooperating lead
roll, buttress roll and mandrel sets; a strip infeed system adapted
for feeding a metal strip to the lead roll set of said tube forming
system; the strip infeed system and said tube forming system being
oriented at an angle .THETA.) therebetween; the strip infeed system
being mounted on wheels for pivotal movement relative to said tube
forming system to vary the angle .THETA.; a motor drive system
operatively connected to the strip infeed system for effecting said
pivotal movement; and a computer system operatively connected to
the motor drive system for operating the motor drive system to
selectively vary the diameter of the forming tube.
4. The apparatus of claim 3, wherein the lead and buttress roll
sets are articulated.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to spiral tubes and
pipes formed by spiralled, joined strips.
[0003] 2. Definitions and Applicability
[0004] The present invention is applicable to spiral tubular
products generally, including both tubes and pipes. Frequently here
for brevity, we use one word or the other, but it is understood the
invention is applicable to both. Also, although the exemplary
system forms smooth wall tubular products, it will be readily
apparent to those familiar with the technology that the invention
is applicable, in addition to smooth wall tubular products, to
profiled (including sinusoidal or corrugated) tubular products.
[0005] 3. Current State of the Relevant Field
[0006] Typically, spiral tubes and pipes are formed to a constant
diameter. The relevant factors (1) strip width, (2) angle of strip
entry into the rolls, and (3) the position of the pressure roll
relative to the other rolls, are held constant to maintain the
desired diameter. Several approaches are available in the
technology to prevent diameter deviations and thus maintain
diameter control in such a system. For example, commonly assigned
U.S. Pat. Nos. 3,650,015 and 3,940,962 describe equipment and
methods for forming spiral tubular products. The '015 patent
describes a unique free-forming approach for forming parallel wall
corrugated tubes. The '962 patent discloses methods and apparatus
for controlling the diameter of spiral tubing made with a
three-roll mill by displacing the joined edges of the helical
convolutions radially relative to the longitudinal axis of the
tubing to correct for diameter deviations. The '015 and '962 patent
are incorporated by reference.
SUMMARY OF THE INVENTION
[0007] In one aspect, the present invention is embodied in
apparatus for forming tapered spiral tubes from strips, which
comprises a tube forming system which forms a strip of material
such as metal into a spiral tube; and a strip infeed system which
is adapted for feeding a strip to the spiral tube forming system.
The tube forming system and the strip infeed system are adapted for
pivotal movement relative to one another to vary the helix angle
between these components and thus vary the diameter of the
resulting spiral tube. The apparatus further includes a drive
system for effecting the desired pivotal movement between the strip
infeed system and the tube forming system; and a computer system
which is operatively connected to the motor drive system for
operating the motor drive system to vary the helix angle as
required.
[0008] In another embodiment, the strip infeed system itself is
adapted for pivotal movement relative to the tube forming system to
vary the helix angle. In yet another embodiment, the strip infeed
system is mounted on wheels for pivotal movement relative to the
tube forming system to effect the desired variation of the helix
angle. In a preferred embodiment, the tube forming system is a
three roll system comprising cooperating lead roll, buttress roll
and mandrel sets.
[0009] Other aspects and embodiments of the present invention are
described in the specification, drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The above and other aspects of the invention are described
below in conjunction with the following drawings.
[0011] FIG. 1 is a simplified, schematic representation of one
embodiment of a taper tube spiral mill apparatus or system in
accordance with the present invention.
[0012] FIG. 2 is a simplified top plan view of a taper tube spiral
mill system in accordance with the present invention.
[0013] FIG. 3 is a side elevation view of the taper tube spiral
mill system of FIG. 2.
[0014] FIG. 4 is an end elevation view of the taper tube spiral
mill system of FIG. 2.
[0015] FIG. 5 is a chart showing the variation of tube diameter as
a function of the helix angle .THETA. as .THETA. is varied
linearly.
[0016] FIG. 6 is a chart showing the variation of tube diameter as
a function of the helix angle .THETA. as .THETA. is varied
sinusoidally.
[0017] FIG. 7 depicts an example of a tapered spiral tube or pipe
formed by the apparatus of FIGS. 1-4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] FIG. 1 is a simplified, schematic representation of one
embodiment 10 of a taper tube spiral mill system or apparatus in
accordance with the present invention. The mill apparatus 10
comprises (1) an infeed section or system 11 for continuously
unwinding a strip 16, FIG. 3, of material such metal, typically
carbon steel; (2) an exemplary three roll spiral tube-forming
machine system 12, for forming the strip into a spiral tube of
controlled, preferably constant slope, varying diameter; and (3) a
discharge section or system 13. The strip infeed section 11 feeds
the strip 16 (hereafter steel strip) into the three roll spiral
tube-forming machine system 12, where the strip is spirally wound
into a tube such as the illustrated tube 17, FIG. 7. The
illustrated apparatus 10 uses a smooth wall pipe mill. However, the
apparatus is applicable to form the various types of spiral pipes
or tubes, including smooth wall welded seam, smooth wall
lockseamed, corrugated lockseamed and corrugated welded seam pipes
or tubes.
[0019] The relationship between the width of a steel strip such as
the exemplary strip 16 and the diameter, d, of the resulting tube
such as 17 is given by the formula: 1 d = FSW sin
[0020] where: d= pipe diameter (see FIGS. 4 and 7),
[0021] FSW= finished strip width, and
[0022] .THETA.=the angle between the infeed section 11 and a line
14 perpendicular
[0023] to the spiral pipe discharge table (the helix angle).
[0024] If the helix angle .THETA. and the finished strip width,
FSW, of the strip 16 being fed into the machine stay constant, the
pipe diameter will also remain constant. However, if the helix
angle .THETA. is varied while the finished strip width remains
constant, the diameter of the tube produced will vary according to
the above formula. If .THETA. is varied while the mill is running,
that is, while strip 16 is continuously fed into the mill and
formed, a tapered tube of changing diameter will result. More
specifically, if the helix angle .THETA. of the mill is increased
as the mill is running, the diameter of the tube will decrease.
Conversely, if the helix angle .THETA. is decreased, the diameter
of the tube will increase.
[0025] Referring now to FIGS. 2-4, in one embodiment according to
the present invention, the taper tube spiral mill system 10
comprises an elongated mill base 18 on which is mounted the
components of the strip infeed system 11. Wheels 19-19, FIG. 3, are
mounted on the bottom side of the mill base 18 and permit the base
to be rolled along the shop floor. A motor-driven screw jack 21 is
connected to the mill base for moving the base bidirectionally to
pivot the infeed system 11 as indicated by arrow 15, FIGS. 1 and 2,
and vary the helix angle .THETA.. The infeed system 11 includes a
conventional uncoiler 22 which is mounted on the mill base 18. A
coil of the steel strip 16 is wrapped around the uncoiler and plays
out along the infeed section 11 to the spiral tube-forming machine
12. (Strip 16 is omitted in FIG. 2 to facilitate viewing the
components of the system.) The strip exiting the uncoiler 22 is fed
to a conventional coil end joiner 23, which squares the trailing
and leading ends of consecutive strips and welds the ends to form
the continuous strip 16.. From there the strip 16 is driven through
the main mill drive system 24, which comprises a plurality of
stands or pairs of rolls, each having an upper roll and a lower
roll. The pairs of rolls receive the strip 16 and drive it into the
spiral machine system 12. Preferably, the spiral machine system 12
comprises three sets of rolls, a lead roll set 25, FIG. 4, a
mandrel set 26, and a buttress roll set 27. As discussed below,
preferably the lead roll set and the buttress roll set are
articulated. The three roll apparatus bends the strip 16 into
spiral tube 17. In the illustrated up curve system 10, the inner
roll of the inner and outer rolls (upper and lower rolls) which
comprise the mandrel roll set 26 serves as a fulcrum. As the strip
16 is driven forward by the drive roll system 24, the opposing lead
roll set and buttress roll set curl the continuously advancing
strip 16 around the mandrel set 26, upwardly in the direction of
arrow 36, in an arc which describes the selected diameter relative
to the center axis 35 of the tube.
[0026] The desired pipe diameter, d, and specifically, the desired
varied diameter profile is effected by a computer or programmable
logic controller system 29, FIG. 2, which is connected to an
electrical motor that drives the screw jack mechanism. The computer
is programmed to control the winding and unwinding of the screw
jack and thus bidirectionally move the infeed section 11 and alter
(increase and decrease) the helix angle .THETA. as required as the
strip 16 is fed to the spiral machine 12. Thus, the
computer-controlled drive system can continuously control
(increase, decrease and/or maintain constant) the helix angle
.THETA..
[0027] As indicated in the above formula, the diameter of the tube
is inversely proportional to the sine of the helix angle .THETA..
Referring to FIG. 5, when the helix angle .THETA. is varied
linearly, as indicated by curve 42, the sides of the tube are not
straight or linear; rather they have a sinusoidal curvature and the
tube diameter varies sinusoidally, as indicated by curve 43. FIG. 6
illustrates that by varying the helix angle .THETA. according to a
sinusoidal profile, curve 44, during the tube formation process,
the tube can have straight sides and the diameter varies linearly,
curve 45. Thus, to obtain a linearly varying, or curved, or
constant diameter profile, the computer 29 is programmed to drive
the screw jack so that the helix angle .THETA. varies sinusoidally,
or linearly, or is maintained constant. In addition, the computer
system 29 can control the helix angle .THETA. to provide
combinations of these profiles along a given tube, that is to
provide different profiles, including positive and negative linear
and curved slopes, along different sections of a tube. In short,
preferably the tube walls are linearly tapered, forming concentric
circles of increasing or decreasing diameter centered about and
perpendicular to axis 35, see FIG. 7. However, the illustrated
apparatus can be used to form constant radius parallel wall tubular
products, or irregularly tapered tubular products, or curved wall
products, or combination products in which different sections have
different wall profiles selected from parallel and/or linearly
tapered and/or curved and/or irregularly tapered.
[0028] Illustratively, at least two methods can be used to vary the
mill helix angle (.THETA.). First, and preferably, as described
above, the helix angle (.THETA.) of the mill can be varied using
the electrically driven screw jack mechanism 21, which is driven by
a motor whose output speed is controlled by the programmable motor
controller. The programmable motor controller can be programmed to
vary the motor speed continuously according to any required
profile. Alternatively, the helix angle (.THETA.) of the mill can
be varied using a rack and pinion drive (or a traction wheel drive)
whose driving speed is varied using by the programmable motor
controller. The driving unit will be mounted to the infeed section
mill base with the rack mounted to the floor.
[0029] The prior art approach described previously uses apparatus
which is referenced to the center line or axis of the constant
diameter tube. In contrast, and referring to FIGS. 4 and 7, to
facilitate manufacturing of varied diameter tubular products, the
present invention preferably uses a common pass line 31, which is
defined by the upper (inner) mandrel roll, FIG. 4, and corresponds
approximately to the bottom center line 32 of the tube 17, FIG. 7.
In a presently preferred arrangement, to maintain the required
location and orientation as the diameter changes, the lead and
buttress roll sets are articulated.
[0030] Instead of the illustrated up curve machine, a down curve
machine may be preferred for forming large diameter spiral tubes.
In the down curve arrangement, the three forming rolls and common
pass line 33 are located at the top of the machine and the
advancing strip 16 curls downward from the top center line 34 of
the tube, FIG. 7, in the direction opposite to that of arrow
36.
[0031] Presently, the system 10 can be used for tubular products
having diameters as small as about 5 inches and to form tubular
products which taper as much as approximately 0.25 inches per foot
of tube length.
[0032] Various types of spiral edge joining and fastening
approaches and materials can be used, including lockseam, submerged
arc welding and high speed welding. Lockseam joining is similar to
that used for spiral corrugated rib pipe product, but with the
lockseam on inside of tube to provide a smooth exterior. It may be
advantageous to use a precoating on steel strip materials to
protect from corrosion. Precoating materials include zinc and/or
aluminum and/or polymers and/or combinations thereof. The submerged
arc welding is the same as for spiral constant diameter pipes. This
involves welding inside and out. Uncoated, mild steel can be used.
Finally, but not exhaustively, high speed weld uses high frequency
contact resistance welding developing a mash lap type of weld
wherein the two strip edges are heated to a plastic state and
pressed one into the other from a top and bottom position. This
system could utilize both precoated zinc strips and uncoated
metals.
[0033] Please note, using the common pass line manufacturing
approach, before separation into individual tubes, the profile of
the continuously formed tube looks somewhat like a saw. One side of
the tube structure is flat and the other side has tapered "saw
teeth" corresponding to the different tapered tubes or tube
sections included in the continuous tube structure. For the
illustrated up curve machine and its bottom common pass line, the
bottom of the continuous tube is flat and the top has the saw tooth
appearance. Referring to FIG. 7 (which depicts one tapered section
or tube), the tube axes 35 of the individual tapered tubes or
tapered tube sections and the associated diameters of the tubes are
oriented at complementary, non-perpendicular acute angles to the
horizontal common pass line 31 (32). This orientation is taken into
account during separation into the individual tubes. For example,
to make each end cut of a tube perpendicular to the pipe axis 35,
one approach is to use a double cut-off process with plasma torches
or with a mechanical cut-off such as friction saws or rotary
cutting tools.
[0034] Regardless of the method used to vary the helix angle
(.THETA.) of the mill, the result will be a tapered tube such as
17, FIG. 7, the final shape of which is controlled by varying the
helix angle (.THETA.) of the mill according to a schedule derived
from the above formula.
[0035] The present invention has been described in terms of a
preferred and other embodiments. The invention, however, is not
limited to the embodiments described and depicted. One familiar
with the art to which the present invention pertains will
appreciate from the embodiments disclosed here, that the present
invention is applicable in general to spiral tubular products,
including corrugated, ribbed and smooth wall spiral tubular
products. The invention is defined by the claims appended
hereto.
* * * * *