U.S. patent application number 10/173722 was filed with the patent office on 2003-12-18 for perforated spiral pipe.
This patent application is currently assigned to Helix International, Inc.. Invention is credited to Castricum, Wilhelmus P.H..
Application Number | 20030230127 10/173722 |
Document ID | / |
Family ID | 29733418 |
Filed Date | 2003-12-18 |
United States Patent
Application |
20030230127 |
Kind Code |
A1 |
Castricum, Wilhelmus P.H. |
December 18, 2003 |
Perforated spiral pipe
Abstract
An improved filter pipe is disclosed, and also an improved
apparatus is disclosed for making the improved filter pipe. The
apparatus is meant for perforating, forming and cutting spirally
formed pipe, particularly spiral pipes having a diameter of
approximately one inch or more. The filter pipe has a unique
corrugated or fluted configuration that adds section modulus to the
pipe, potentially allowing for the use of thinner sheet metal in
manufacturing such pipes and in filters made from such pipes. A
machine for manufacturing the spiral pipe may include special
machinery for forming the unique corrugated or fluted
configuration.
Inventors: |
Castricum, Wilhelmus P.H.;
(Ormond Beach, FL) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60611
US
|
Assignee: |
Helix International, Inc.
|
Family ID: |
29733418 |
Appl. No.: |
10/173722 |
Filed: |
June 18, 2002 |
Current U.S.
Class: |
72/49 |
Current CPC
Class: |
B01D 29/111 20130101;
B01D 29/333 20130101; B21C 37/126 20130101; B21C 37/121 20130101;
B21C 37/124 20130101; B21C 37/127 20130101 |
Class at
Publication: |
72/49 |
International
Class: |
B21C 037/12 |
Claims
What is claimed is:
1. An apparatus for forming spiral pipe from a metal strip, the
apparatus comprising: forming rollers for forming lateral edge
portions of the metal strip; a forming head having a lateral bore;
a forming tool extending into the lateral bore of the forming head;
a closing assembly for coupling and compressing lateral edge
portions of the metal strip into a lockseam of a pipe; and rollers
for perforating the metal strip and driving the metal strip around
the forming tool, against an interior surface of the forming head,
and in an axial direction, wherein the lateral edge portions of the
strip mate and are coupled and compressed to form a lockseam and
provide a continuous spiral pipe.
2. The apparatus of claim 1, wherein the rollers for perforating
yield perforations selected from the group consisting of square and
rectangular perforations.
3. The apparatus of claim 1 wherein the rollers for perforating the
metal strip and driving the metal strip comprise a first set and a
second set of rollers.
4. The apparatus of claim 1 wherein the forming tool extending into
the lateral bore of the forming head is a mandrel and the closing
assembly includes at least one roller protruding through an opening
in the top of the forming head.
5. The apparatus of claim 1 wherein the forming tool is a boom
extending into the lateral bore of the forming head and the closing
assembly includes a support roller inside the forming head and a
clinching roller.
6. The apparatus of claim 1, further comprising a cutting assembly
for cutting a pipe section from the spiral pipe.
7. An apparatus for forming spiral pipe from a strip of metal, the
apparatus comprising: rollers for forming edge portions of the
strip; a forming head for providing an external guide for the metal
strip, the forming head having an entrance for the metal strip and
an interior surface which has a predetermined radius of curvature;
a mandrel rotatable about its centerline, positioned inside the
forming head, the mandrel providing a guide for an interior surface
of the metal strip and a compression surface for forming a lock
seam; rollers for perforating and driving the metal strip into the
forming head entrance, around the mandrel, against the interior
surface of the forming head, and in an axial direction, wherein the
edges of the strip mate to form a spiral cylinder, the rollers for
perforating and driving only contacting the metal strip prior to
entry into the forming head entrance; and a closing assembly
external to the mandrel for deforming and coupling the mated edges
of the strip to form a lockseam in a spiral pipe.
8. The apparatus of claim 7, wherein the rollers for perforating
yield perforations selected from the group consisting of square and
rectangular perforations.
9. The apparatus of claim 7 wherein the rollers for perforating and
driving the metal strip comprise a first and a second set of
rollers, each of the sets of rollers for performing one of
perforating and driving the metal strip.
10. The apparatus of claim 7, further comprising a cutting assembly
for cutting a pipe section from the spiral pipe.
11. A method of forming a filter pipe, the method comprising:
drawing a strip of sheet metal into a forming machine; forming seal
forms on a first edge and a second edge of the sheet metal; drawing
the metal and forming perforations in the sheet metal after the
seal forms are formed; forming the strip into a spiral; sealing the
first and second edge of the sheet metal into a lockseam; and
cutting a filter pipe from the formed strip.
12. The method of claim 11, wherein the perforations are
substantially in the form selected from the group consisting of a
rectangle and a square.
13. The method of claim 11, wherein the perforations are severed
from the sheet metal.
14. The method of claim 11, wherein the perforations are retained
on the sheet metal and are raised from a surface of the sheet metal
to a height of from about one to about three times a thickness of
the sheet metal.
15. The method of claim 11, wherein the perforations are from about
thirty percent to about seventy percent of a surface area of the
filter pipe.
16. The method of claim 11, wherein a thickness of the sheet metal
is from about 0.010 inch to about 0.030 inch (from about 0.25 mm to
about 0.76 mm).
17. The method of claim 11, wherein the step of perforating the
metal is completed before the step of drawing the metal.
18. A punch for perforating sheet metal, the punch comprising: a
roller having a plurality of protrusions radially extending from
the roller, the protrusions arranged in at least two
circumferential rows on the roller, the at least two
circumferential rows staggered on a circumference of the roller,
wherein the protrusions cause at least one of openings,
perforations and corrugations in the sheet metal.
19. A combination of the punch according to claim 18 and a die, the
die comprising a roller and at least two grooves for mating with
the protrusions.
20. The combination of claim 19, further comprising a drive gear on
at least one of the punch and the die.
21. The punch according to claim 18, wherein the at least two
circumferential rows are staggered at an angle of from about ten
degrees to about thirty degrees.
22. The punch according to claim 18, wherein the protrusions form
at least one of openings, perforations and corrugations in the
sheet metal, but does not sever scrap from the sheet metal.
23. The punch according to claim 18, wherein the protrusions form
at least one of openings, perforations and corrugations in the
sheet metal, and do sever scrap from the sheet metal.
24. The punch according to claim 18, wherein the plurality of
protrusions have sharp edges on two sides and radiused edges on two
sides.
25. The punch according to claim 18, wherein a depth of the punch
is from about two to about four times the thickness of the sheet
metal.
26. A filter pipe, comprising: sheet metal having a first edge and
a second edge, and also having a first end and a second end; a
lock-seam formed by locking the first edge to the second edge, in
forming a spiral-shaped pipe; and a plurality of perforations in
the filter pipe allowing communication between an inside of the
filter pipe and an outside of the filter pipe, at least one side of
the perforations forming an angle from about ten to about forty
degrees to a plane of the sheet metal.
27. The filter pipe of claim 26, wherein an outside diameter of the
pipe is from about 0.5 inches to about 1.5 inches.
28. The filter pipe of claim 26, where the perforations are about
thirty percent to about sixty percent of a surface area of the
filter pipe.
29. The filter pipe of claim 26, wherein the perforations are
substantially in a form selected from a group consisting of a
rectangle and a square.
30. An oil filter further comprising the filter pipe of claim 26.
Description
FIELD OF THE INVENTION
[0001] This invention relates to an improved apparatus for
producing spirally formed pipe, particularly spiral pipes having a
diameter of approximately one inch or more.
BACKGROUND
[0002] A large potential for small diameter spiral pipes exists in
the filter market, such as automobile oil filters. These filters
typically have a perforated inner metal cylinder that is
approximately one inch in diameter. Because pipes such as those
used in oil filters need to be accurately and cleanly cut in large
quantities, a pipe forming and cutting apparatus capable of fast
and accurate cuts is necessary. There are several known ways to
form and cut a pipe. A pipe may be formed by spirally or helically
winding a continuous strip of metal, and joining adjacent edges of
the wound strip to form a spiral lockseam in the pipe. In some pipe
forming and cutting machines, the spirally formed pipe is cut by
moving a knife outside the pipe into an overlapping position with a
knife inside the pipe. Other types of spiral pipe forming and
cutting machines use multiple knives or rotate the knives around
the pipe to cut the pipe into sections.
[0003] The performance of the oil filter depends on the performance
of the spiral pipe, typically an oil outlet at the center of the
filter, where a strong flow of oil must be maintained for engine
performance, and a strong filter must be maintained to resist
pressure and insure functioning of the filter. Oil inflow is
typically achieved by perforating the spiral formed pipe, that is,
by punching holes in the inlet pipe so that oil can flow from the
pipe into a downstream filter element. The filter element is
typically paper, but need not be, and may be made from any of a
number of other materials. The perforations in the center pipe
necessary for the filter to function may be achieved in one or more
of several ways. The strip or coil used for the central pipe may be
perforated off-line, that is, in a separate operation.
[0004] Prior art perforations and machinery for perforating sheet
metal typically included punches and dies that performed a unit
operation off-line before the strip was fed into the spiral tube
forming machine. A typical prior art punch 105 is depicted in FIG.
11b. The punch 105 is V-shaped, having a low portion 104 and two
high portions 114. The punch forces strip or sheet metal into a
die, such as the die 115 depicted in FIG. 11a. As shown in FIG.
11c, these tools produce perforated sheet metal 107. The surface of
the sheet metal 108 is pierced by V-shaped perforations 109. These
perforations allow communication between one side of the metal and
the opposite side, necessary for a filter. Typically, surface 108
becomes the outer surface of the filter pipe which is later formed,
while the pierced portions 108 remain on the inside.
[0005] There are several drawbacks to the prior system and method.
For example, the V-shaped punch is prone to chipping and breaking.
This method results in very high tool wear, when chipping 106 or
other damage occurs on the punch 105. Also, the configuration of
the perforation, with two "high points" 114 and their separation
from sheet metal surface 108, does not strengthen the pipe, but
instead may form weak points, where the metal is stressed and may
tear. In addition, to maintain flow of oil or other fluid medium,
there must be sufficient distance between the pipe itself and the
"tips" 114 of the V. The tips can be no further away from the sheet
metal surface 108 than the tensile strength of the metal will
allow, or there will be tears in the resulting pipe. This could
lead to uncontrolled flow of oil or other medium.
[0006] What is needed is an improved way to perforate and form
sheet metal for filter pipe with a pattern that yields longer tool
life and does not require an off-line operation. What is needed is
a better way to form perforated filter pipe.
BRIEF SUMMARY
[0007] One aspect of the invention is a filter pipe. The filter
pipe comprises sheet metal having a first edge and a second edge,
and having a first end and a second end. The pipe also comprises a
lock seam formed by locking the first edge to the second edge in
forming a spiral-shaped pipe. The filter pipe also has a plurality
of perforations or flutes, the perforations or flutes allowing
communication between an inside of the filter pipe and an outside
of the filter pipe. At least one side of the perforations forms an
angle of from about ten to about forty degrees to a plane of the
sheet metal. In one embodiment, the perforations or flutes are
generally in the shape of a rectangle or a square, joined to the
sheet metal with two sloping sides and two open sides, the open
sides allowing communication between an inside of the filter pipe
and an outside of the filter pipe.
[0008] Another aspect of the invention is a method for forming a
filter pipe. The method comprises drawing a strip of sheet metal
into a forming machine, and forming seal forms on a first edge and
a second edge of the sheet metal. The method also includes drawing
the metal and forming perforations or flutes in the sheet metal,
after the edges are formed. The method then forms the strip into a
spiral. The first and second edges of the sheet metal are sealed to
each other to form a lockseam. The pipe is then cut to a desired
length.
[0009] Another aspect of the invention is an apparatus for forming
a spiral pipe from a metal strip. The apparatus comprises rollers
for forming lateral edge portions of the metal strip. The apparatus
comprises a forming head having a lateral bore for guiding for the
metal strip into a spiral pipe. The apparatus further comprises a
forming tool extending into the lateral bore of the forming head.
The apparatus also comprises a closing assembly for coupling and
compressing lateral edge portions of the metal strip into a
lockseam of a pipe. The apparatus also has rollers for perforating
and driving the metal strip around the forming tool, against an
interior surface of the forming head, and in an axial direction,
wherein the lateral edge portions of the strip mate and are coupled
and compressed by the closing assembly to form a lockseam and
provide a continuous spiral pipe.
[0010] Another aspect of the invention is a punch for perforating
sheet metal. The punch comprises a roller having a plurality of
protrusions radially extending from the roller, the protrusions
arranged in at least two circumferential rows on the roller, the at
least two rows staggered on a circumference of the roller, wherein
the protrusions cause at least one of openings, perforations and
corrugations in the sheet metal, but do not cause portions of the
sheet metal to separate from the sheet metal. There are many ways
to practice the invention. These and many other aspects of the
invention will become apparent from the drawings below and the
detailed descriptions of the preferred embodiments.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0011] FIG. 1 is a perspective view of the back and right sides of
a preferred embodiment of the present invention.
[0012] FIG. 2 is an elevation view of the back side of FIG. 1.
[0013] FIG. 3 is a plan view of FIG. 1.
[0014] FIG. 4 is an elevation view of the right side of FIG. 1.
[0015] FIG. 5 is a left side, elevational view of the forming head
assembly of FIG. 1.
[0016] FIG. 6 is an front, elevational view of the forming head
assembly of FIG. 1.
[0017] FIG. 7 is a plan view of the top side of the forming head
assembly of FIG. 1.
[0018] FIGS. 8 and 14 are side elevational views of a part of a
spiral pipe forming machine forming a part of the present
invention.
[0019] FIGS. 9a-9d are sectional views of the edge forming and
corrugation rollers that are used in the spiral pipe forming
machine, with the strip edge configuration illustrated between the
rollers.
[0020] FIG. 10 is a sectional view of the guide plates and clamping
members that are used in the spiral pipe forming machine.
[0021] FIGS. 11a-11c depict a prior art punch and die set useful
for making perforations in sheet metal.
[0022] FIGS. 12a-12g depict perforated coilstock and filter pipe
according to a variety of embodiments of perforations or
flutes.
[0023] FIGS. 13a-13e depict upper and lower rollers useful in the
present invention for driving and perforating coil stock.
[0024] FIG. 15 is a front, sectional view of an upper bracket and
pipe support assembly for use in the apparatus of FIG. 1.
[0025] FIG. 16 is a cross-sectional view taken along line 12-12 of
FIG. 15.
[0026] FIG. 17 is a fragmentary side view of the upper bracket and
pipe support assembly of FIG. 15 with the outer knife in a cutting
position.
[0027] FIG. 18 is a fragmentary side view of the upper bracket and
pipe support assembly of FIG. 15 with the outer knife in a stand-by
position.
[0028] FIG. 19 is a front sectional view of a support assembly for
use in the apparatus of FIG. 1.
[0029] FIG. 20 is a magnified view of inset A of FIG. 19.
[0030] FIG. 21 is an alternate embodiment of a pipe-making
machine.
[0031] FIG. 22 depicts a method for making a perforated spiral
pipe.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0032] Referring now to the drawings, FIGS. 1 and 2 depict the
spiral pipe forming apparatus 10 useful in making pipes according
to the present invention. Many elements of the pipe forming machine
10 are conventional, and are described in greater detail in U.S.
Pat. No. 5,636,541, issued Jun. 10, 1997. The disclosure in that
patent is incorporated by reference herein, and made a part hereof.
Many of the parts disclosed therein can be used in the present pipe
forming machine 10 with some adaptation to accommodate the one and
one-half inch wide strip 15 and its particular edge and the flutes
or corrugation/perforation configurations that are used in the
present pipe forming machine 10.
[0033] FIGS. 8 and 14 depict some of the elements of pipe forming
machines 10, 100. The machine 10, 100 includes a frame 11 and a
control cabinet 12. A control panel 13 contains a plurality of
control elements 14, such as knobs, gauges and dials, for
controlling and monitoring the operation of the pipe forming
machine 10, 100 and the slitter 75. The functions of the various
control elements are described in U.S. Pat. No. 4,706,481, issued
Nov. 17, 1987. The disclosures contained in that patent are hereby
incorporated by reference in their entirety.
[0034] A continuous metal strip 15 is fed into the frame 11 of the
pipe forming machine 10, 100. To make one inch diameter filter
pipe, the strip 15 is preferably 1.5 inches wide. If the pipe
diameter increases, a wider strip 15 can be used and is preferred.
The metal strip 15 passes through a roller housing 16 that contains
a plurality of rollers that bend the edges of the strip 15a into a
predetermined shape for forming a lockseam. FIGS. 9a-9d show the
upper edge forming rollers 16-u and the lower edge forming rollers
16-l that are preferably used for forming the strip edges in
forming filter pipe. The strip 15 first passes through the rollers
shown in FIG. 9a, and successively through the rollers shown in
FIG. 9b through FIG. 9d. Further information about the function and
operation of the edge forming rollers is disclosed in U.S. Pat. No.
4,567,742, which is hereby incorporated by reference in its
entirety and made a part hereof.
[0035] Returning to FIGS. 8 and 14, a lower drive roller 17 and an
upper drive roller 18 are rotatably mounted in the frame 11. The
drive rollers cooperate to pull the metal strip 15 into the frame
11 and through the roller housing 16. The two drive rollers 17, 18
then push the metal strip 15 between the upper guide plates 19 and
lower guide plates 20. The width of the drive rollers 17, 18 and
the guide plates should be adapted to conform to the width of the
strip 15. As shown in FIG. 10, the lower guide plates 20 are
secured to the frame 11 by bolts 20a. The lower guide plate 20 also
contains grooves to accommodate the edges formed in the strip 15.
Clamps 20b are pivotally connected to a base 20c that is attached
to the frame 11. The clamps 20b hold the upper guide plates 19
against the lower guide plates 20.
[0036] The strip 15 can be perforated before entering the pipe
forming machine 10, or in the pipe forming machine 10 with
perforating drive rollers 17, 18. In FIG. 8, lower drive roller 17
and upper drive roller 18 are perforating rollers that also drive
the strip through the pipe-forming machine. In FIG. 14, there are
two sets of rollers, first set 17 and 18, and second set 17b and
18b. Either configuration may be used to drive the strip through
the pipe forming machine and will also perforate the rollers as
desired.
[0037] An improved perforation extends the metal no more than
necessary and also strengthens the metal by adding "corrugations."
FIG. 12a depicts strip 15 with "square" flutes or perforations 15b,
each having two sloping sides 15c and two openings 15d. The sloping
sides 15c provide continuity of metal and insure that the ribs will
continue to form a continuum with the strip, that is, a continuous
piece of sheet metal, with no welds or other means for attaching.
The openings 15d will allow oil or other medium being filtered to
communicate from one side to the other when the spiral pipe is used
as the central pipe in a filter.
[0038] In a preferred embodiment, the flutes or perforations 15b
are substantially in the form of a square or a rectangle. The angle
formed by the plane of the sheet metal and the sloping sides 15c
may be any angle consistent with good tooling and manufacturing
practices. The perforations may be formed by drawing or punching
the metal to a depth of from about two times to about four times
the thickness of the metal, with a depth of about three times
preferred. This technique is sufficient to enable perforations that
are large enough for good medium flow through a filter made from
the filter pipe. The resulting flutes or perforations are also
sufficient to "corrugate" or "reinforce" the filter pipe with added
dimensional stability. By limiting the draw or deformation of
metal, this process also prevents or at least limits tearing the
metal at corners of the perforations.
[0039] Using perforations or flutes 15b as shown in FIG. 12a may
result in a strengthened filter pipe section 23a because of the
reinforcing nature of the apertures 15b, as shown in the filter
pipe section 23a in FIG. 12b. Rather than being arranged in rows
perpendicular to a longitudinal axis of the metal strip,
perforations may be formed at an angle C to a horizontal axis of
the sheet metal. That is, each row of perforations may be staggered
from the adjacent rows by a portion of a perforation, thus forming
an "angle" or circumferential distance from the adjacent rows.
Thus, each row of perforations is offset from the other rows,
preventing stress concentrations in the metal and in the resulting
pipe. The pipe section 23a has been formed into a spiral shape with
lock seams 23b. A cross sectional view of pipe section 23a is shown
in FIG. 12c, in which the filter pipe section 23a has an outside
surface 23c, an inside surface 23d, and the perforations 15b
preferably reside on the inside of the pipe section 23a. In other
embodiments, the perforations may be on the outside. Flutes or
perforations formed as a rectangle or square are preferred.
[0040] In one embodiment, the indentations or perforations have a
pitch from about 1/4 inch to about 1/2 inch, as shown in FIG. 12a.
A pitch of about 0.365 inch to 0.375 inch is particularly
preferred. Indentations from about 0.25 inches square to about
0.375 inches square are preferred, as are rectangular indentations
having sides of about this size. The axial spacing of the
indentations may vary, as does the pitch. There should be
sufficient space between the indentations or perforations to insure
the strength of the resulting filter pipe. Areas between
indentations are preferably from at least about 0.100 inches to
about 0.200 inches. The sheet metal resulting from this processing
desirably uses a considerable extent of its available surface area
for these flutes, indentations, apertures, or perforations. The
perforations preferably occupy from about thirty to about seventy
percent of the surface area of the sheet metal, not including the
edges of the sheet metal devoted to the lock seams or the forms on
the edges that are later made into lock seams. Calculations to
determine the area devoted to these features may include the
transitions, such as sloping sides 15c as part of the area of the
perforations or indentations 15b. Although the embodiment of FIG.
12a illustrates uniformly spaced perforations of a uniform shape, a
mixture of perforation shapes fabricated in the same pipe with any
of a number of spacings or patterns between perforations is also
contemplated.
[0041] The preferred embodiments described above cause a separation
or kerf between surfaces of the sheet metal strip that is
perforated, but no metal is actually severed from the metal strip
and no pieces of scrap are generated. In addition to the
indentations described above, other perforations and indentations
may be used in embodiments of the present invention. Fluid
communication between the outside and inside of the filter pipe may
be achieved by processes that result in complete separation of
pieces or metal from the metal strip, that is, processes that
generate scrap from the sheet metal, and thus from the resulting
pipe. Therefore, for purposes of this disclosure, perforation means
a penetration or an opening in sheet metal whether scrap is
generated or not. Besides the square and rectangular retained
perforations, other openings in the sheet metal, and therefore the
resulting pipe, are meant to be included in the present disclosure.
For instance, FIG. 12d shows a triangular perforation in sheet
metal 15, the perforation retained on the sheet metal. FIG. 12e
shows a polygonal perforation in sheet metal, again retained on the
sheet metal. FIG. 12f depicts a perforation in which the scrap 15e
is severed from the sheet metal 15; such a configuration will work
but is less preferred and may also be in the prior art. FIG. 12g
includes another configuration in which the perforation is raised
from sheet metal 15 and scrap 15e is severed from the sheet metal.
The configuration shown in FIG. 12g may require a two-step
operation, preferably a first punching step to sever the scrap and
a second drawing step to form the raised portion or dimple in the
sheet metal. Two sets of perforating rollers, as shown in FIG. 14,
may be used for these operations. The punches should register
within 0.001-0.002 inches of each other. This configuration allows
a "dimpling" effect on the resulting pipe, less than a "corrugating
effect," but still useful in lending dimensional stability. All the
above configurations, and their equivalents, are meant to be
included in the embodiments of the invention
[0042] Machinery to create these flutes or perforations is also
revealed herein. The drive rollers 17, 18 may be used as a punch
and die to perforate the strip 15 as it enters the pipe forming
machine 10. In a preferred embodiment, the lower drive roll is the
punch and the upper drive roll acts as a die, although in other
embodiments, the upper and lower drive rolls may be reversed. FIGS.
13a and 13b depict drive rollers 17 and 18 formed as a punch and
die, respectively. In FIG. 13a, the upper drive roller 18 has 6
lands or raised surfaces 18a with 5 grooves or lower surfaces
between the lands, for receiving and forming sheet metal pushed
into the die by punch 17 with raised surfaces 17a.
[0043] FIG. 13c depicts one such raised surface 17a, with corner
radii R on two sides and forming an angle B with the surface of the
punch. Corner radii R and angle B will be reproduced in the sheet
metal or strip that is perforated by drive rollers 17, 18. In one
embodiment, angle B is from about 15 degrees to about 30 thirty
degrees, but other angles may also be used. The radius used in the
corner is preferably 0.040 inches, but may also take on other
values as desired, and radii from about 0.010 inches to about 0.060
inches may also be used. The raised surface of FIG. 13c will
produce the perforation or corrugation depicted in FIG. 12a. The
other two sides S of raised surface 17a have sharp edges for
piercing and separating portions of a strip of sheet metal passing
between rollers 13a and 13b. The raised surface 17a will preferably
have a depth (or height) of about two to three times the thickness
of the metal strip to be processed through the rollers. The raised
surfaces of the punch of FIG. 13a and the die of FIG. 13b cause the
sheet metal to deform on radiused edges and cause separation or
kerf on sharp edges, between the plane of the sheet metal and the
corrugation formed. In preferred embodiments, there is no severing
of the metal from the metal strip and thus no pieces of scrap
produced.
[0044] In a preferred embodiment, as shown in FIG. 13c, the raised
surface 17a is configured with rounded corners having radii R so
that sheet metal will deform but not separate where the surface
comes in contact with each corner radius R and will only separate
where sharp edges S of the raised surface come in contact with the
metal strip. An advantage of this configuration is that wear on the
roller is reduced and there are no narrow, sharp regions on the
teeth or raised surfaces that might chip or dull quickly. Further,
the resulting square or rectangular perforations produced by the
rollers of FIGS. 13a and 13b have parallel openings or separations
on two opposite sides while leaving the sheet metal connected on
the other two opposite sides, shown in FIG. 12a. The invention is
meant to include any technique consistent with sheet metal arts and
good manufacturing practices.
[0045] Particulars about the flutes or perforations may be varied
as desired. In one preferred embodiment, the raised surfaces 17a
are staggered circumferentially as shown in FIG. 13b, and also
shown earlier in FIG. 12b, at an angle C to an axis of the drive
roller. In one embodiment, the angle may be about fifteen degrees.
Other punches or perforating drive rollers may use other angles.
This design staggers the impact and the load of the sheet metal
formation on the drive rollers and may help "average" the effective
instantaneous load over each turn or partial turn of the drive
rollers.
[0046] The drive rollers will typically be part of a larger set of
tools used within the pipe-forming machinery. As shown in FIGS. 13d
and 13e, the drive rollers are part of an assembly or combination.
FIG. 13d depicts a die assembly 130, which is preferably used in an
upper roller assembly. The die assembly 130 comprises a roller 131
and a die 132, the die having at least two grooves 138 for mating
with punches from another roller assembly. The die 132 is mated to
the roller 131 with a key 137 and a lock ring 133. There may also
be a spacer ring 136 to space the assembly 130 in the pipe forming
machine. There may preferably also be a gear 134 for driving the
assembly and a second spacing ring 135. The assembly 130 is
preferably mounted on a shaft through the center (not shown) for
driving or being driven by conventional driving components within
the pipe-forming machine 10.
[0047] A mating roller assembly 140 shown in FIG. 13e provides
punches for the die of FIG. 13d. Assembly 140 is preferably used in
a lower roller assembly. The assembly is similar, except for the
protrusions that this assembly provides. There is a roller 141 and
a punch 142, mated by key 149 and lock ring 143. The punch 142 has
at least two rows of protrusions 142'. There is a spacer ring 146
for proper spacing of the assembly 140 within the pipe-forming
machine. There is preferably a gear 144, mating with gear 134 for
driving the assembly, and a second spacing ring 145. The gears and
their drivetrain should be designed and assembled to be
backlash-free. The assembly 140 is preferably mounted on a shaft
through the center (not shown) for driving or being driven by
conventional driving components.
[0048] The sheet metal used for filter pipe is preferably
tin-plated or cold-rolled steel, although the invention is not
limited to this embodiment. Typical alloys that may be suitable
include 1010 and 1020, in thicknesses from about 0.010 inches to
about 0.030 inches. Galvanized steel, stainless steel, and other
alloys may also be used. Coilstock thicker or thinner may also be
used consistent with the strength and performance desired from the
finished pipe. The flutes or perforations used are preferably drawn
to a depth or height less than about five times the thickness of
the sheet metal used, and preferably about two or three times the
thickness of the sheet metal. For example, if SAE 1020 strip 0.020
inches thick is being perforated, the gap between the bottom
surface of the sheet metal and the bottom surface of the
perforation is desirably about 0.040 inches (twice the metal
thickness) and the perforation itself is also displaced an
additional 0.020 inches (the thickness of the metal). The gap and
the thickness of the metal combine for a total displacement of
three times the thickness of the metal. Other perforation
dimensions are also possible, and may further depend on whether the
user desires to remove or retain the perforation or aperture.
[0049] Referring now to FIGS. 1 through 5, a forming head assembly
21 and a mandrel assembly 22 with cover plates 65, 67 cooperate to
form the perforated metal strip 15 into a spiral pipe 23. The
forming head assembly 21 includes a base 27 which is detachably
secured to a forming head table 28. A clamp 26 is used to secure
the forming head base 27 to the forming head table 28. As best
shown in FIGS. 5 and 6, the forming head assembly 21 also includes
a forming head 29 which is bolted to the forming head base 27. The
forming head 29 is enclosed around a lateral bore 30. In one
embodiment, the metal strip 15 is formed inside of the lateral bore
30 into a spiral pipe having a diameter of approximately one inch
to about five inches. Helical grooves 32 are provided for the
formed edges 15a of the strip 15 and the resulting lockseam 24.
Grooves 32 help guide the helically-wound strip 15 and spiral pipe
23 through the forming head 29. The inner diameter of the lateral
bore 30 determines the outer diameter of the spiral pipe 23. If the
diameter of the spiral pipe is to be varied, a forming head 29 with
a different diameter lateral bore 30 should be used.
Interchangeable forming heads with different diameter lateral bores
can be used in a preferred embodiment of the present invention. In
one embodiment, the pipe forming apparatus of the present invention
may be used to make spiral filter pipe one to two inches in
diameter from a one and one-half inch wide perforated metal strip
15. It is expected that spiral pipe as small as one-half inch (1/2
inch) in diameter can be made with the pipe forming apparatus 10 of
the present invention. The present invention is not limited to
making perforated filter pipe and may also be modified to produce
larger or smaller pipe diameters using wider strip.
[0050] The forming head 29 mates with a removable inset 33. The
inset 33 is held in place by pins (not shown). The radius of
curvature of the removable inset 33 is smaller than the radius of
curvature of the lateral bore 30. The inner surface of the
removable inset 33 can be coated with a friction reducing material.
The removable inset 33 is intended to prevent the strip 15 from
locking up as it is driven around the lateral bore 30 of the
forming head 29.
[0051] Referring to FIGS. 5-7, a lock seam closing roller assembly
50 is positioned on top of the forming head 29. The rotational axis
of the lock seam roller head 52 is oriented in a laterally angled
position, as shown in FIGS. 5-7. The lock seam closing roller head
52 protrudes through an opening in the top of the forming head 29
and contacts the folded helically wound strip edges. The roller
head 52 is rotationally attached to an end of a shaft 51. Bearings
inside the roller head 52 allow the roller head to be passively
rotatable. The shaft 51 passes through an upper roller holder 53
that is attached to the top of the forming head 29 by threaded
bolts 54. The roller shaft 51 is also eccentric and has a hexagonal
end 51a that can be accessed through an opening in the upper roller
holder 53 (see FIG. 7). The lock seam roller head 52 can be
adjusted vertically relative to the helically wound strip 15 by
turning the hexagonal end 51a of the shaft 51. A set screw 56
adjusts the lock seam roller head 52 axially with respect to the
folded, helically-wound strip edges. A nut 55 holds the set screw
56 in place. In this top view of the forming head, bore 45 is shown
in phantom.
[0052] Referring to FIGS. 1, 2 and 5, the spiral pipe 23 is not
only formed inside the enclosed forming head 29, but at the same
time is formed around a completely cylindrical mandrel 60. The
clearance between the mandrel 60 and the surface of the lateral
bore 30 in the forming head 29 is approximately twice the thickness
of the metal strip, plus 0.006-0.003 inches each side. The closely
controlled clearance between the mandrel 60 and enclosed forming
head 29 provides greater accuracy in producing pipe having a
consistent diameter. If there is too much clearance, the strip 15
will buckle in the forming head. If there is too little clearance,
the strip 15 will lock up inside the forming head. For a more
detailed discussion of a suitable pipe forming apparatus, reference
is made to U.S. Pat. No. 4,924,684 issued May 15, 1990. The entire
disclosure of U.S. Pat. No. 4,924,684 is incorporated by reference.
The preferred embodiment of the present invention also includes an
apparatus for slitting the spiral pipe made with the pipe forming
apparatus 10. The present slitting apparatus 75 includes many
elements of the slitting apparatus disclosed in U.S. Pat. Nos.
4,706,481 and 4,924,684. The descriptions of the slitting apparatus
contained in these patents, as well as the disclosure in their
entirety, are hereby incorporated by reference.
[0053] Referring now to FIGS. 1-4 and 15-18, an inner knife 80 is
attached to a boom 81 with a bolt 82. A washer 83 is positioned
between the bolt 82 and the inner knife 80. The inner knife 80 has
an oversized central opening 84 (not shown), which permits the
position of the inner knife to be adjusted in any radial direction
relative to the inner surface of the spiral pipe 23. In general,
the knife 80 will be centered within the spiral pipe 23. It is
preferred that the inner knife can be centered within the pipe
without an oversized opening 84.
[0054] The boom 81 passes through the mandrel 60, and is free
floating within the mandrel 60. Thus, the boom 81 does not
necessarily rotate with the mandrel, but is designed to rotate only
during this slitting process. The boom is preferably passively
rotatable, i.e., it is rotationally driven by the overlapping inner
knife 80 and outer knife 110 during the slitting process. Other
embodiments are possible, however, wherein the boom is drivably
rotatable. To provide the passive rotation, the end of the boom 81
opposite the inner knife 80 is surrounded by combination
needle/thrust bearings (not shown). These needle/thrust bearings
can be obtained from IKO Bearings, of Arlington Heights, Ill. The
bearings are held in a boom holder assembly 86 by an annular
support member 87, a lock washer 88, and a lock nut 89.
[0055] The boom holder assembly 86 has an upper section 90 and a
lower section 91. Each section has a central semi-cylindrical
cavity which abuts the annular support member 87. The upper section
90 and the lower section 91 are clamped to each other by a
plurality of alien bolts 92. The lower section 91 is mounted on an
attachment block 93, and fixed thereto by alien bolts 94. The
attachment block 93 passes between guide shafts 95, and is secured
to a shaft connector 96 by alien bolts (not shown). A plurality of
alien bolts 97 squeezed together the ends of the shaft connector 96
around the guide shafts 95, so that the shaft connector 96 slides
axially with the guide shafts 95. The guide shafts 95 pass through
openings in the forming head table 28, and slide through the
bearing housings 98, which preferably include THK Slide Bearing SC
30 assemblies. There are four such bearing housings 98, each of
which is attached to the top of a mounting leg 99 by alien bolts
101. The four mounting legs 99 are provided to support the mandrel
assembly 22 and the slitting apparatus 75 at the correct height
with respect to the forming head table 28 and the pipe 23. The
mounting legs 99 are attached to the base plate 102 by alien bolts
103. The base plate 102 is attached to the pipe forming machine 10.
Oval pivot slots (not shown) are provided in the base plate 102, so
that the pipe cutting apparatus can be pivoted about the center of
the inner knife 80. Most of the bolts that connect the various
components of the boom assembly 86 pass through oval slots so that
the position of the components can be adjusted relative to each
other.
[0056] As can be seen in FIG. 1-4 and in FIGS. 15-18, an outer
knife 110 is generally positioned below the inner knife 80 and
outside of the pipe 23. The outer knife is held in a vertical
holder 111 by a lock washer and lock nut 114 that are connected to
the shaft of the knife. Bearings (not shown) permit the outer knife
110 to be passively rotatable, that is, rotationally driven by
contact with the rotating pipe 23. The vertical holder 111 is
attached to a slide bearing assembly 111a (not shown) (e.g., THK
Roller Table Type VRM 3105A). The slide bearing assembly 111a is
also attached to the central portion of a knife slide block 112.
The vertical holder 111 and outer knife 110 can thus slide up and
down relative to the knife slide block 112. The knife slide block
112 has two cylindrical openings through which the guide shafts 95
pass. A plurality of allen bolts 113 squeeze together the sides of
these openings around the shafts 95, so that the knife slide block
112 is also affixed to and slides axially with the guide shafts
95.
[0057] During the pipe forming process, the outer knife 110 should
be maintained in a standby position, where it will not interfere
with the spirally moving pipe 23. When it is time to cut the pipe,
the outer knife blade is moved to a cutting position, where it
punctures the spiral pipe 23 and overlaps the inner knife 80 (see,
e.g., FIG. 17).
[0058] The outer knife blade 110 is moved into and out of its
cutting position by the pneumatic cylinder assembly 116. This
assembly includes a pneumatic cylinder 117 that controls a piston
118. A lower clevis 119 is attached to the piston 118 and a set of
links 120, 121. The lower links 120 are pivotally connected to the
clevis 119 and an arm 122 which is integral with and extends from
the central portion of the knife slide block 112. The upper toggle
links 121 are pivotally connected to the clevis 119 and the bottom
of vertical holder 111. Thus, when the piston 118 is fully
extended, the vertical holder 111 and outer knife 110 will be
raised vertically into the cutting position where the cutting edges
of the inner and outer knives overlap and puncture the pipe 23. See
FIGS. 2, 4, and 17. When the piston 118 is retracted into cylinder
117, toggle links 120 and 121 will collapse and pull down the
vertical holder 111 and the outer knife 110 to the standby
position. See FIG. 1.
[0059] An upper clevis 123 is attached to the top of the cylinder
117. The upper clevis 123 is pivotally connected to a threaded
shaft 124. Nuts 125 secure the threaded shaft 124 to one end of a
cylinder support bracket 126. The other end of the cylinder support
bracket 126 is attached to the central position of the knife slide
block 112. The vertical holder 111 and slide bearing assembly 111a
(not shown) are connected to the opposite side of the knife slide
block 112. As a result of its connection to the knife slide block
112, the cylinder support bracket 126 and other components of the
pneumatic cylinder assembly 116 move axially with the guide shafts
95. The threaded shaft 124 of the pneumatic cylinder assembly 116
permits adjustment of the standby and cutting positions of the
lower knife 110.
[0060] As shown in FIG. 1, and also in FIGS. 15-18, the slitting
apparatus 75 of the present invention also includes a pipe support
assembly 230. The support assembly 230 includes a support sleeve
231 mounted on a sleeve holder 232. The sleeve is removably affixed
to the sleeve holder 232 by bolts 235. The sleeve holder 232 is
secured to an upper bracket 233 by bolts 234 extending vertically
through the sleeve holder 232 and upper bracket 233 such that it is
fixed in a radial direction with respect to the pipe 23.
[0061] During the pipe forming process, the support assembly 230 is
maintained in a fixed position where it does not interfere with the
spirally moving pipe 23 (see, e.g., FIGS. 16 and 18). When it is
time to cut the pipe and the outer knife 110 is moved to its
cutting position, the support sleeve 231 will keep the pipe from
being deflected where it contacts the spiral pipe (see, e.g., FIG.
17). The support sleeve 231 is positioned at the end of the pipe
and preferably surrounds the pipe. The support sleeve 231 thus
operates to prevent the boom 81 from deflecting upward or laterally
in response to the force exerted by the outer knife 110.
Additionally, the sleeve prevents the pipe material at the cut end
from flaring out as it is being cut.
[0062] With small diameter pipes (i.e., approximately 1 inch), it
is difficult to keep the boom 81 rigid when the outer knife 110
engages the pipe 23. If the boom 81 deflects away from the outer
knife 110 during the cutting process, the inner and outer knives
will move apart and will not overlap to cut the pipe. The support
sleeve 231, by limiting deflection of the pipe, maintains the inner
and outer knives in an overlapping relationship during the slitting
process. The support sleeve 231 is preferably constructed from a
heat-treated steel such as AlSI A2 steel. It may be noted that many
of the components of the pipe forming apparatus 10 and slitter
apparatus 75 are made of tool steel (58.degree.-62.degree. HRc),
CRS or Mehanite.
[0063] Referring to FIG. 15, the sleeve 231 substantially surrounds
the pipe material to be cut. The sleeve is configured such that a
predetermined distance, preferably 0.005 inch, is maintained
between the outer diameter of the pipe and the inner diameter of
the sleeve. The sleeve therefore preferably has an inner diameter
241 that is about 0.010 inches greater than the predetermined outer
diameter of the pipe being cut. Different size support sleeves 231
may be constructed to accommodate specific pipe diameter
requirements. In one embodiment, the sleeve 231 surrounds the
entire circumference of the pipe where the pipe enters the sleeve
and surrounds approximately 270 degrees of the pipe's circumference
leaving a gap where the outer knife engages the pipe. In another
embodiment, the sleeve may surround the entire circumference of the
pipe and not have a gap. When the embodiment of a sleeve with no
gap is used, the outer knife engages the pipe outside of the
sleeve.
[0064] FIGS. 16-18 illustrate the extended upper portion 236 of the
sleeve. The upper portion of the sleeve 232, opposite the outer
knife 110, preferably has a width of 1.5 inches extending axially
from approximately 1.3 inches behind the cutting edge of the inner
knife 80 toward the pipe forming portion of the apparatus to
approximately 0.2 inches past the cutting edge of the inner knife.
The sleeve also includes a beveled or tapered receiving edge 237.
The tapered receiving edge preferably extends around the entire
inner diameter of the sleeve and aids in guiding the pipe through
the sleeve. The recessed lower portion 238 of the sleeve 231
permits necessary clearance for the outer knife 110 to engage the
pipe 23.
[0065] As best shown in FIGS. 19 and 20, the support sleeve 231
also preferably includes an angled edge 244. The angled edge 244 is
positioned on one side of the recessed lower portion 238 of the
sleeve 231. When a section of pipe rotates between the inner and
outer knives during a cut, sharp or jagged edges may develop at the
newly formed pipe edges. The pipe forming and cutting apparatus 10
may jam due to the sharp edges catching on the sleeve 231 as the
newly cut edges are rotated in the sleeve. A more gradual
transition to the preferred 0.005 inch clearance between the sleeve
231 and pipe is accomplished with the angled edge 244. In one
embodiment, the angled edge 244 forms approximately a 15 degree
angle with the vertical axis. In other preferred embodiments, this
angle may be optimized for the type of material to be cut or for
different cutting applications. By providing a gradual transition
for a freshly cut edge of a pipe rotating in the sleeve, the angled
edge minimizes potential jamming difficulties.
[0066] The description so far has focused on pipe forming machines
using a mandrel inside the forming head, the metal strip being
wrapped around the mandrel by the forming head to form the filter
pipe. Other embodiments of pipe forming machines may also be used
to form pipes, especially those for pipes having larger diameter,
such as 2" to about 5" in diameter (from about 50 mm to about 125
mm). Certain embodiments are further described in U.S. Pat. No.
4,706,481, the contents of which are hereby incorporated by
reference. It is easier for large diameter pipes to utilize a boom
and an inside roller and an outside roller, rather than a mandrel
and forming head.
[0067] One embodiment of a machine with these features is depicted
in FIG. 21. A pipe forming machine 200 for forming larger diameter
pipe includes a boom 240 and a forming head 241. The forming head
241 is mounted to the forming head base 242 by clamping bars 249,
251 and bolts 253. In a preferred embodiment, the forming head base
is movable on guide rails 255. The forming head 241 curls the metal
strip 15 into a cylindrical spiral, whereby the opposing preformed
edges of the strip 15 mesh. The meshed edges are then compressed
between a support roller 243 and a clinching roller 245 to form a
lockseam. The metal strip, as described above for other pipe
forming machine embodiments, is continuously pushed by the drive
rollers so that a hollow cylindrical metal pipe is continuously
produced with a spiral lockseam. The clinching roller 245 is moved
into and out of its clinching position by a conventional hydraulic
cylinder assembly 247. The hydraulic cylinder assembly 247 includes
a yoke 257 which holds the clinching roller 245. The yoke is
appended to a piston rod 263 which slides in and out of cylinder
head 261. The cylinder head 261 is attached to the cylinder barrel
259 by bolts 265. The hydraulic cylinder assembly 247 provides the
pressure on clinching roller 245 to close the lockseam on the
filter pipe.
[0068] Referring again to FIG. 4, the support assembly 230
preferably attaches to the upper bracket 233 which is connected to
opposite ends of the knife slide block 112. The upper bracket 233
includes an overhead member 233-U bolted to the tops of two
vertical members 233-F and 233-B. The bolts pass through oval slots
in the overhead member 233-U, which permit angular adjustment of
the support sleeves position. The support sleeve is connected to
the overhead member 233-U via the sleeve holder 232 and support
bolts 234. Each vertical member of the upper bracket 233 includes
oval slots 233-S. These oval slots 233-S permit the height of the
overhead member 233-U, and hence the position of the support
assembly 230, to be adjusted. Although fixed in a radial direction
with respect to the pipe 23, the support sleeve 231 moves in the
axial direction of the pipe during the cutting operation because
the upper bracket 233 is connected to the guide shafts 95 via the
knife slide block 112. A slide 147 is provided to catch pipe
sections 23a that have been severed by the slitter apparatus 75.
The slide 147 has a vertical flange 148 that is connected to the
cylinder support bracket 126. Thus, the slide 147 also moves in
unison with the cutting knives 80, 110 and support sleeve 231
during the cutting operation.
[0069] When the outer knife 110 punctures the pipe 23 and overlaps
the inner knife 80, the guide shaft system allows the axially
moving pipe to push the overlapping knives and the support sleeve,
and their connected components, in unison with the pipe. An axial
motion cylinder assembly 150 is provided to assist the axial
movement of the pipe cutting apparatus 75. As best shown in FIG. 2,
this assembly 150 includes a pneumatic cylinder 151 which is
supported by a piece of flat stock 152, and held in place by a nut
153. The flat stock 152 is attached to a mounting leg 99. The
piston 154 is secured to a second piece of flat stock 155 by a pair
of nuts 156. The second piece of flat stock 155 is bolted to the
central inner portion of the shaft connector 96. When air is
supplied to the cylinder 151 in one direction, the piston 154
extends out of the cylinder, and pushes the shaft connector 96, and
its connected components, in the axial direction of the pipe 23.
When the air to the cylinder 151 is reversed, the piston 154
retracts and pulls the inner and outer knives 80, 110, back to
their starting or "begin-cut" position.
[0070] A stop/shock-absorber mechanism 160 is provided to fix the
begin-cut position of the inner and outer knives. (See FIG. 2.)
This mechanism comprises a mounting plate 161 which is attached to
the forming head table 28. A commercially available
hydraulically-dampened plunger 162 extends through the mounting
plate 161 in the axial direction of the pipe. The plunger 162 is
held in place by nuts 163, which mate with the threaded portions of
the plunger 162. A plastic tip 164 is mounted on the piston (not
shown) of the plunger 162. The stop/shock-absorber assembly 160
serves two functions. First, it serves as a stop, which sets the
begin-cut position of the pipe slitting apparatus 75. When the
axial motion of the piston 154 fully retracts, a strip of flat
stock 165 attached to the upper bracket 233 comes to rest again the
plastic tip 164 of the fully retracted plunger 162 as shown in FIG.
2. Thus, the nuts and threaded portions of the plunger 162 can be
adjusted to set the begin-cut position. In the second function,
when the piston 154 extends and pushes the upper bracket 233 and
flat strip 165 away from the stop/shock-absorber mechanism 160, a
spring (not shown) in the plunger 162 pushes its piston (not shown)
and plastic tip 164 out of the plunger 162. When the upper bracket
233 and flat strip 165 return to the begin-cut operation, they will
push the plastic tip 164 and its piston into the plunger 162, until
the upper bracket 233 returns to the begin-cut position. While the
piston is pushed back into the plunger 162, it provides a hydraulic
cushion or shock-absorber effect on the upper bracket 233 and its
connected components.
[0071] A proximity sensor 170 is also mounted in the mounting plate
161 adjacent to the stop/shock absorber mechanism 160. The sensor
170 is connected to the slitter control circuit, and prevents the
slitting process from beginning if the slitter is not completely in
its begin-cut operation. If the slitter is not in its begin-cut
position and the slitting process begins, the axial motion piston
154 will reach its end of travel before the pipe 23 is fully
severed.
[0072] In the pipe forming machine 10 a perforated strip of metal
15 is pulled into the roller housing 16 by the drive rollers 17 and
18. In the roller housing 16, the strip is corrugated and the edges
of the strip are formed in the shapes desired to produce a spiral
lockseam. Drive rollers 17 and 18, or drive rollers 17, 17b, 18,
18b then perforate the strip and push the perforated, corrugated
and edge-formed strip through the guide plates 19 and 20 and into
the forming head assembly 21. The strip is driven around the
rotatable mandrel 60 and inside the lateral bore 30 of the forming
head 29. The metal strip is driven between the mandrel 60 and
inside the lateral bore 30 of the forming head 29. The metal strip
is driven between the mandrel 60 and forming head 29 in a helical
manner, so that the outer edges of the strip are positioned
adjacent to each other in helical fashion. The folding rollers 36
and 37 cooperate to fold the adjacent, mated edges of the helically
wound strip. The lockseam closing roller 52 compresses the folded
strip edges against the mandrel 60 to form a tight lockseam 24.
During the pipe forming operation, the mandrel 60 is passively
rotatable and pivotable, thereby eliminating friction that might
otherwise cause the helically wound strip and pipe to lock up
between the mandrel 60 and forming head 29.
[0073] As the spiral pipe production continues, the pipe 23 moves
out of the forming head block 29 in a helical fashion. That is, the
pipe 23 moves in its axial direction while it rotates. During the
pipe production process, the outer knife 110 is in its standby
position, as well as in the begin-cut position. Thus, the pneumatic
cylinder assemblies 116, 150 have their respective pistons fully
retracted. When the pipe 23 reaches its desired length, air is sent
to both of these pneumatic cylinder assemblies to fully extend
their respective positions. Thus, the pneumatic cylinder assembly
116 pushes the outer knife 110 upward so that it punctures the pipe
23 and overlaps the inner knife 80. The pneumatic cylinder assembly
150 extends its piston, which pushes all of the components and
outer knives and the support sleeve, in the axial direction of the
pipe. As the pipe forming machine 10 continues to produce the pipe
23 in a spiral manner, the pipe moves axially with, and rotates
between the overlapping inner knife 80 and the outer knife 110.
After the pipe completes one revolution, the section of the pipe
23a in front of the overlapping knives will be completely severed
and will fall into slide 147.
[0074] Once the cutting process is complete, the air supplied to
the pneumatic cylinder assemblies 116, 150 will be reversed. As a
result, the outer knife 110 will be returned to its standby
position, and the piston 154 will pull all the components connected
to the guide shafts 95, including both knives and the support
sleeve, back to the begin-cut position.
[0075] Referring now to FIGS. 2, 8 and 14, to operate the cutting
apparatus 75 in an automatic mode, an electrical encoder 27' is
coupled to the lower drive roller 17, or lower drive rollers 17 and
17b, of the pipe producing machine 10 by a pulley belt 28'. The
encoder 27' is adapted to generate pulses corresponding to the
number of rotations of the lower drive roller 17 or 17b. These
pulses are transmitted over a cable 29' to a control box 44'. The
control box 44' is programmed to check for a first pulse count
corresponding to the desired length of the pipe, a second pulse
count corresponding to a slow-down point for pipe production, and a
third pulse count corresponding to the amount of axial travel of
the pipe required for the pipe to be completely cut by the cutting
apparatus 75. Three counters 45', 46' and 47' are included in the
control box 44'. These counters can be incremented or decremented,
one pulse at a time. The first pulse count (i.e., pipe length) is
set with the first counter 45', the second pulse count (i.e.,
slow-down point) is set with the second counter 46', and the third
pulse count (i.e., cut length) is set with the third counter 47'.
The control box 44' sends pneumatic signals to the pneumatic
cylinders 117,151 over line 48' in response to the first, second
and third pulse counts.
[0076] The control box 44' also has four control switches 147',
148', 149', and 150'. A first control switch 147' selects manual or
automatic control of the pipe cutting apparatus 75. In the manual
mode, the second, third and fourth control switches 148', 149' and
150' are operable to manually actuate the pneumatic cylinders 117,
151. That is, the second control switch 148' may be used to move
the piston rod 118 in and out of its cylinder 117, and thereby move
the outer knife 110 into and out of its cutting position. The third
control switch 149' may be used to move the piston 154 in and out
of its cylinder 151, and hence slide the inner knife 80, outer
knife 110 and support sleeve 231 in the axial direction of the pipe
23. When the first control switch 147' is put into automatic mode,
the second, third and fourth control switches 148', 149' and 150'
are deactivated, and all three counters 45', 46' and 47' are reset
to zero. The pipe cutting apparatus 75 will automatically cut the
pipe 23 into sections 23a as pipe is produced on pipe forming
apparatus 10.
[0077] The control panel 13 is provided with an on/off switch for
the pipe cutting machine 75 and three speed adjustment knobs 135',
136' and 137'. The first speed adjustment knob 135' controls the
production speed of the pipe as it is formed with the pipe forming
machine 10. The second speed adjustment knob 136' controls the
speed at which the pipe is formed prior to the outer knife 110
moving from its standby position to its cutting position. In order
to consistently obtain pipe sections that are cut to the same
length, it is important that the pipe 23 travels at a constant,
relatively slow speed while the outer knife 110 moves from its
standby position to the cutting position. A relatively low speed
minimizes the effect of any pulse count errors on the length of the
pipe sections 23a. Thus, prior to moving the outer knife 110 to the
cutting position, it is preferred that the pipe production is
slowed from its fastest, most efficient production speed to a
transitional, "slow-down speed." The second speed adjustment knob
136' controls this speed. The third speed adjustment knob 137'
controls the speed of the pipe production while the outer knife 110
moves to, and is in, the cutting position where it cooperates with
the inner knife 80 and support sleeve 231 to cut the pipe 23. The
cutting speed is usually set at one-half the production speed, or
whatever speed is convenient. The speed control knobs 135', 136',
137' can be used to adjust the production speed, slow-down speed
and cutting speed of the pipe cutting apparatus 75 during both
manual and automatic modes of operation.
[0078] The cutting apparatus 75 operates in conjunction with the
pipe producing machine 10 in automatic mode in the following
manner. The spiral pipe forming process is initiated with the pipe
forming machine 10 in a known way. When the leading edge of the
pipe 23 begins to leave the forming head 29, the pipe producing
machine is temporarily halted, and the pipe cutting apparatus 75 is
energized by turning on the on/off switch on the control panel 13.
The pneumatic cylinder assemblies 116,150 are initialized to be in
their standby positions, so that the outer knife 110 does not
overlap the inner knife 80. The first counter 45', the second
counter 46', and the third counter 47' are set to zero. Air is sent
to the axial motion cylinder 151 to fully retract piston 154, so
that the inner and outer knives are in the begin-cut position.
[0079] Typically, the pipe cutting apparatus 75 will be initially
operated in its manual mode to cut a few sections of pipe to
determine the optimum positional adjustments for the inner knife
80, outer knife 110 and support sleeve 231. The pipe cutting
apparatus 75 then run in and out of automatic mode a few times to
find the optimum settings for the production speed, slow-down
speed, cutting speed, and the pulse counts for the pipe length,
slow-down point, and cut length. Once these variables are
determined, the pipe cutting apparatus 75 is ready for continuous
automatic operation.
[0080] In a typical example of automatic operation, the first
counter 45' may be set to 1250 pulses for pipe length, the second
counter 46' may be set to 1100 pulses for the slow-down point, and
the third counter 47' may be set to 375 pulses for the cut length.
A cutting cycle begins by resetting all three counters 45', 46',
47' to zero, and by cutting the part of the pipe 23 that extends
past the inner and outer knives will in the begin-cut position.
This part of the pipe will be referred to as the "leading
section".
[0081] When the pulse count is at zero in all three counters, the
control box 44' sends a first pneumatic pulse signal, via line 48',
to the pneumatic cylinder assembly 116. The piston 118 is thereby
energized and pushed downward to its extended position. The outer
knife 110 is thereby moved to the cutting position where the
cutting edges of the inner and outer knives puncture the pipe 23.
The first pneumatic pulse signal also reverses the direction of air
supplied to the axial motion cylinder 151, so that the piston 154
pushes the shaft connector 96, and all components connected to the
guide shafts 95, axially with the pipe. The pipe forming machine 10
continues to produce the pipe 23 in a spiral manner. The pipe 23
thus moves axially with, and rotates between, the overlapping inner
knife 80 and the outer knife 110. The encoder 27' generates a train
of pulses that correspond to the length of the next section of pipe
being formed, which has its leading edge at the overlapping knives.
This section of pipe will be referred to as the "new section." All
three counters 45', 46', 47' count in unison as the new section of
pipe is formed and the leading section of pipe is severed.
[0082] The guide shafts 95 allow the inner and outer knives to move
in the axial direction of the pipe under the forces provided by the
new section of pipe pushing on the overlapping knives and the
extension of the axial motion piston 154. Thus, the inner knife 80,
outer knife 110 and support sleeve 231 cooperate to cut the
complete circumference of the leading section of pipe as the pipe
moves axially and rotates between the inner and outer knives. The
third pulse count will be set at the number of pulses corresponding
to the axial travel corresponding to slightly more than one pipe
rotation. It is generally preferred to have a little overlap in the
cut to assure that the leading pipe section is completely
severed.
[0083] When the third pulse count is reached, the third counter 47'
stops counting, but the first and second counters 45' and 46'
continue to count as the new section of pipe continues to be
produced. Also, the control box 44' sends a second pneumatic pulse
signal to the pneumatic cylinder assemblies 116,150 along line 48'.
This second pneumatic signal indicates that the cutting process is
completed, and thus operates the pneumatic cylinders 117, 151 to
fully retract their respective pistons. The outer knife 110 is then
moved to its standby position. The air supplied to the cylinder 151
is also reversed, so that the piston 154 pulls the cutting assembly
75 mounted on the guide shafts 95 back to its begin-cut position.
When the third pulse count is reached, the new section of pipe also
stops being produced at the cutting speed, and begins to be formed
at the production speed.
[0084] The new section of pipe will continue to be produced at the
production speed, and the first and second counters 45', 46' will
continue to count pulses, until the second pulse count is achieved.
At that time, the slowdown point will be reached. The second
counter 45' will stop counting, and the new section of pipe will be
formed at the slow-down speed. The new section of pipe will
continue to be formed at the slow-down speed, and the first counter
45' will continue to count pulses, until the first pulse count is
reached. The first pulse count indicates that the new section of
pipe has reached its desired length. When the first pulse count is
reached, all three counters are reset to zero, and cutting process
just described is repeated for the new section of pipe. The same
cutting process will continue to be repeated as additional sections
of pipe are produced.
[0085] The control scheme just described for the pipe cutting
machine 75 is preferred because the pulse counts for the pipe
length, slowdown point and cut length can be set independently, and
the cut length is automatically accounted for in the pipe length.
Moreover, the foregoing control scheme is preferred for cutting the
spiral pipe into sections up to approximately five feet in length.
For longer sections of pipe, the first pulse counter can be
eliminated, and a limit switch connected to the pipe runoff table
can be used to indicate that the desired pipe length has been
reached. Other control schemes and considerations are disclosed in
U.S. Pat. No. 4,823,579 issued Apr. 25, 1989. The control schemes
disclosed in that patent, as well as all other disclosures in that
patent, are hereby incorporated by reference.
[0086] The invention may be practiced in many ways. One embodiment
of the invention is a method of forming a perforated spiral pipe.
One step of the method is to draw coilstock or a strip of sheet
metal into a machine for forming spiral pipe. A second step is to
form indentations or perforations in the strip, which may be formed
by the same drive rollers that propel the strip into the machine.
The method includes one or more steps of forming seal forms on the
edges of the strip, and then forming the strip into a spiral. The
edges of the strip are then sealed to form a lockseam, and a
desired length of pipe is cut and released from the machine. The
method may include other steps as desired for further finishing the
pipe so produced.
[0087] It should be understood that changes and modifications to
the preferred embodiment described above will be apparent to those
skilled in the art. It is intended that the foregoing description
be regarded as illustrative rather than limiting, and that it is
the following claims, including all equivalents, which are intended
to define the scope of the invention.
* * * * *