U.S. patent application number 09/783647 was filed with the patent office on 2001-09-13 for mechanical pipe expander.
Invention is credited to Hausler, Karl Heinz, Kolbe, Manfred, Toputh, Arno.
Application Number | 20010020381 09/783647 |
Document ID | / |
Family ID | 7632256 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010020381 |
Kind Code |
A1 |
Kolbe, Manfred ; et
al. |
September 13, 2001 |
Mechanical pipe expander
Abstract
A mechanical pipe expander with a pyramidal polyhedron and with
segments which are arranged on the circumferential surfaces of the
polyhedron and can be moved radially by axially displacing the
polyhedron relative to the segments. A wear lining is arranged
between each of the surfaces of the polyhedron and each respective
segment.
Inventors: |
Kolbe, Manfred;
(Monchengladbach, DE) ; Toputh, Arno;
(Monchengladbach, DE) ; Hausler, Karl Heinz;
(Korschenbroich, DE) |
Correspondence
Address: |
Thomas C. Pontani, Esq.
Cohen, Pontani, Lieberman & Pavane
Suite 1210
551 Fifth Avenue
New York
NY
10176
US
|
Family ID: |
7632256 |
Appl. No.: |
09/783647 |
Filed: |
February 14, 2001 |
Current U.S.
Class: |
72/393 |
Current CPC
Class: |
B21D 39/20 20130101 |
Class at
Publication: |
72/393 |
International
Class: |
B21D 041/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 18, 2000 |
DE |
100 08 688.8 |
Claims
We claim:
1. A mechanical pipe expander comprising a pyramid polyhedron
having a central axis and circumferential surfaces; segments
arranged on the circumferential surfaces of the polyhedron, which
segments are moved radially by relative axial movement of the
polyhedron; and a wear-resistant lining between each of the
circumferential surfaces and each respective segment.
2. The mechanical pipe expander as claimed in claim 1, wherein the
wear-resistant lining is made of a carbon fiber composite, with a
polymer matrix.
3. The mechanical pipe expander as claimed in claim 2, wherein
graphite powder is added to the matrix, in such an amount as to
give a coefficient of friction between 0.10 and 0.15 for the wear
lining.
4. The mechanical pipe expander as claimed in claim 1, wherein the
segments have axial end faces which are provided with the
wear-resistant linings.
5. The mechanical pipe expander as claimed in claim 1, wherein the
pyramidal polyhedron is a truncated pyramid.
6. The mechanical pipe expander as claimed in claim 1, wherein the
polyhedron has an octogonal cross-section.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a mechanical pipe expander with a
pyramidal polyhedron and with segments which are arranged on the
jacket surfaces of the polyhedron and can be moved radially by
means of an axial displacement of the polyhedron relative to the
segments.
[0003] 2. Description of the Related Art
[0004] Expanders of this type are used in the production of large
welded steel pipes. After welding, the pipes are widened slightly
in diameter in order to calibrate the internal diameter, to round
the pipes, and to increase the apparent yield strength by
cold-forming. Since the pipe materials are sometimes of
considerable strength and the pipes can have thick walls,
extraordinarily high forces occur upon expansion. For this reason,
pipes measuring up to 18 meters in length are widened in
stages.
[0005] DE-AS 22 64 207 discloses a suitable expander for this
purpose. The actual expander head comprises a pyramidal polyhedron
which has individual segments arranged on its surfaces. By
displacing the polyhedron relative to the segments, these can be
moved radially so that the diameter of the expander head increases
or decreases.
[0006] Another expander is known from U.S. Pat. No. 4,064,730,
which document particularly concerns the guiding of the segments on
the polyhedron.
[0007] On account of the very high forces, high surface pressures
occur in the guide tracks. This leads to a situation where only
selected and expensive material pairings, for example hardened and
ground cold-work steel on hardened and ground alloyed gray cast
iron, can take up such surface pressures. In addition, the running
surfaces have to be lubricated with a special oil in order to keep
the wear within reasonable limits. The oil must be easy to wash off
since it wets the pipes on the insides and has to be removed from
them. Special oils of this kind are expensive, so that high
production costs result from the wear on the tools and from these
oil costs.
SUMMARY OF THE INVENTION
[0008] It is therefore an object of the invention to make available
a mechanical pipe expander in which the wear on the surfaces moving
relative to each other can be reduced and in which the use of
lubricating oil in these areas can be dispensed with.
[0009] In a pipe expander of the generic type, this object is
achieved by arranging a wear-resistant lining between the surfaces
of the polyhedron and the segments.
[0010] This wear lining is preferably made of a carbon fiber
composite with a polymer matrix.
[0011] Graphite powder is preferably added to the matrix,
specifically in such an amount as to give a coefficient friction of
between 0.10 and 0.15 for the wear-resistant lining.
[0012] Such a wear lining can additionally also be arranged on the
end faces of the segments.
[0013] By using the wear-resistant lining according to the
invention, not only is it possible to do without the expensive
special oil for lubricating the sliding surfaces, but in addition
comparatively less expensive materials can be used both for the
segments and for the polyhedron. A further advantage of omitting
the oil lubrication is that washing the pipes after expansion
requires less outlay. Lastly, wear no longer occurs on the segments
and on the polyhedron, so that only the wear-resistant linings
themselves have to be replaced.
[0014] Using the wear-resistant lining according to the invention
has a final added advantage. If sets of wear linings of different
thicknesses are kept available, the diameter range within which the
mechanical pipe expander can be used can be substantially
increased, without having to make changes to the segments or to the
polyhedron itself.
[0015] Other objects and features of the present invention will
become apparent from the following detailed description considered
in conjunction with the accompanying drawings. It is to be
understood, however, that the drawings are designed solely for
purposes of illustration and not as a definition of the limits of
the invention, for which reference should be made to the appended
claims. It should be further understood that the drawings are not
necessarily drawn to scale and that, unless otherwise indicated,
they are merely intended to conceptually illustrate the structures
and procedures described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 shows a simplified longitudinal section through a
pipe expander, and
[0017] FIG. 2 shows a corresponding transverse section.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0018] The pipe expander 1 has a polyhedron 2 (here a truncated
pyramid having an octogonal cross-section) which can be axially
displaced by means of a pull rod 6. Segments 3 are arranged on the
circumferential surfaces of the polyhedron. A wear-resistant lining
5 is in each case arranged between the opposing sliding surfaces of
the segments 3 and the polyhedron 2. An additional wear-resistant
lining 5 is also present on the end face of each segment 3. In
order to hold the wear-resistant linings 5 in position,
corresponding recesses can be provided on the underside of the
segments 3. As is known, by means of an axial displacement of the
polyhedron 2 relative to the segments 3, these are moved radially
outward so that in this way expansion of the pipe 4 is
possible.
[0019] Thus, while there have shown and described and pointed out
fundamental novel features of the invention as applied to a
preferred embodiment thereof, it will be understood that various
omissions and substitutions and changes in the form and details of
the devices illustrated, and in their operation, may be made by
those skilled in the art without departing from the spirit of the
invention. For example, it is expressly intended that all
combinations of those elements and/or method steps which perform
substantially the same function in substantially the same way to
achieve the same results are within the scope of the invention.
Moreover, it should be recognized that structures and/or elements
and/or method steps shown and/or described in connection with any
disclosed form or embodiment of the invention may be incorporated
in any other disclosed or described or suggested form or embodiment
as a general matter of design choice. It is the intention,
therefore, to be limited only as indicated by the scope of the
claims appended hereto.
* * * * *