U.S. patent application number 11/355203 was filed with the patent office on 2006-09-14 for expansion device for hollow bodies.
Invention is credited to Helmut Rothenberger.
Application Number | 20060201228 11/355203 |
Document ID | / |
Family ID | 36481361 |
Filed Date | 2006-09-14 |
United States Patent
Application |
20060201228 |
Kind Code |
A1 |
Rothenberger; Helmut |
September 14, 2006 |
Expansion device for hollow bodies
Abstract
An expansion device for hollow bodies, such as pipe ends having
a base body (1) in which a bore (11) for the axial guidance of a
displaceable, a tapering spreading member (10) is disposed, and
having an expansion head (13) which contains a thimble ring (14),
and sector-shaped spreader jaws (15) and is releasably joined to
the base body (1). The spreader jaws (15) are guided for radial
displacement in the thimble ring (14) by the axial movement of the
spreading member, and friction surfaces are provided with a coating
of a hard material to reduce attrition. In one embodiment at least
the portion of the spreading member (10) that acts upon the
spreader jaws (15) is provided with a coating (18) made of the hard
material, e.g., titanium nitride (TiN).
Inventors: |
Rothenberger; Helmut;
(Konigstein, DE) |
Correspondence
Address: |
FULBRIGHT & JAWORSKI, LLP
666 FIFTH AVE
NEW YORK
NY
10103-3198
US
|
Family ID: |
36481361 |
Appl. No.: |
11/355203 |
Filed: |
February 15, 2006 |
Current U.S.
Class: |
72/393 |
Current CPC
Class: |
B21D 41/021
20130101 |
Class at
Publication: |
072/393 |
International
Class: |
B21D 41/02 20060101
B21D041/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2005 |
DE |
10 2005 010 494.0 |
Claims
1-9. (canceled)
10. An expansion device for hollow bodies comprising a basic body
in which a bore is disposed for the axial guidance of a
displaceable, tapering spreading member; an expansion head which
contains a thimble ring with sector-shaped spreading jaws and is
releasably fastened to the basic body; wherein the spreading jaws
are guided for radial displacement in the thimble ring by the axial
movement of the spreading member, and wherein slide surfaces are
provided with an attrition reducing coating of a hard material,
wherein at least the portion of the spreading member acting on the
spreading jaws is provided with the coating of the hard
material.
11. The expansion device according to claim 10, wherein the hard
material comprises titanium nitride (TiN).
12. The expansion device according to claim 10, wherein the coated
surface of the spreading member has a conical surface.
13. The expansion device according to claim 10, wherein the
spreading member is fastened replaceably to a driving rod which is
positioned in the bore of the basic body.
14. The expansion device according to claim 10, wherein interior
surfaces of the spreading jaws are made as sectors of a conical
surface and are coated with the hard material.
15. The expansion device according to claim 14, wherein the hard
material comprises titanium nitride (TiN).
16. The expansion device according to claim 10, wherein the
exterior surfaces of the spreading jaws are configured as sectors
of a cylinder surface and are coated with the hard material.
17. The expansion device according to claim 16, wherein the hard
material consists of titanium nitride (TiN).
18. The expansion device according to claim 10, wherein the coating
is applied by a process selected from the group consisting of
physical vapor depositions (PVD), chemical vapor deposition (CVD)
and physico-chemical vapor deposition (PCVD).
Description
FIELD OF THE INVENTION
[0001] The invention relates to an expansion device for hollow
bodies.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] On account of the very complex geometric and friction
conditions, which are explained at length in the detailed
description, the spreading member in particular is subject to high
and irregularly distributed stresses which definitely shorten the
desired service life of the device.
[0003] An expansion device of the kind in question of the plier
type has been known since 1970 through U.S. Pat. No. 3,550,424. The
document deals with the problem that enormous internal stresses are
produced in the manual device and that to overcome them a staged
drive is to be used for the hand lever so as to reduce the manual
stresses. But it is not the stresses involved in the system and the
resultant wear that are reduced thereby, but the far greatest part
of such stresses are caused by steel-on-steel friction. Since about
the same time such devices have come on the market world-wide in
great numbers.
[0004] Through DE 38 26 187 A1, in the course of the further
development of such expansion devices a likewise generic expansion
tool with a toggle lever drive and an adjustable adapter ring has
become known. Due to the adapter ring it is possible to even out
the influence of axial tolerance errors, but in the range between
the spreading member and the spreader jaws and the wear produced
therein, this has no influence, however, on the stresses in the
area between the spreading member and the spreader jaws and the
wear they cause, and no attrition-reducing surface coating is
disclosed.
[0005] In the ROMPP CHEMIE LEXIKON, Georg Thieme Verlag Stuttgart,
New York, 1995, vol. T-Z, pages 4631-4632, under "Titannitrid,"
(titanium nitride) it is known in the prior art to use this
material for thin layers, as a hard substance for protection
against wear on fine machine bearings, antifriction bearings,
cutting tools and the like and for lining reaction vessels for
molten metals and for coating watch cases and decorative goods. In
the cases last mentioned, the gilt look of the coating is probably
a deciding factor. Nothing is said about its use in the case of
complex conditions of stress and friction between the critical
parts of expansion devices.
[0006] DE 103 43 869 B3 discloses a standing device for an
expansion lance of unspecific length for tubular hollow shapes, in
which a hydraulic liquid, a so-called fluid, expands the expanding
lance. The latter is held perpendicular in a clamping and holding
device, which is arranged preferably in one piece, over a pressure
distributing block with an introduction top. The introduction top
has a through bore whose upper end is widened by a first conical
surface and forms an insertion aid. At the bottom end of the
expansion lance a double cone is held by means of a cap nut, the
lower conical part cooperating with a second conical surface which
is likewise arranged in the pressure distributing block, which thus
has two hollow conical surfaces. The entire combination of convex
and conical surfaces forms nothing more than a liquid-tight
high-pressure connection within the stationary apparatus. For the
creation of high resistance to pressure and attrition it is stated
that the pressure distributing block can be provided with a hard
surface coating of, for example, titanium nitride. However, no
transition from surface pressure on edges or linear pressures takes
place at the contact surfaces. Also, the surfaces in contact in the
area of the titanium nitride coating do not participate in the
expansion process but form only a pressure-resistant coating. Such
a device is neither provided nor suitable for a hand tool.
[0007] It is known through DE 26 54 102 C2, in the case of a
replaceable expansion head, to provide a screw cap and the
expansion jaws at the places at which friction occurs, with a
slippery coating, such as hard chromium for example. This
recommendation, however, disregards the fact that, in the case of
the frequently expensive basic apparatus which is designed for a
plurality of different and also accessory expansion heads, an often
greater wear occurs, especially when expansion jaws coated
accordingly, are in frictional engagement with the unprotected
spreading member of the basic unit. The protective coating of a
component of a pair of parts in frictional engagement always
conflicts with an unprotected component, especially when the latter
is especially endangered due to its slender geometry.
[0008] It is to be noted in this case that such apparatus have been
on the market since the middle of the 1960's, i.e., about 40 years.
The visible parts, including the screw cap or sleeve, which are
visible externally and under stress are already always
chrome-plated, and mainly for reasons of appearance, in conjunction
with protection against contact with the hand and with other tools
or tool kits of craftsmen. In those days pipe connections were
still made mainly threaded couplings and threading dies. Expansion
technology, however, has become much more widespread in recent
years. The hidden or barely visible parts, such as the spreading
member and its completely concealed internal guidance are still
uninfluenced thereby. The inventor has found that this is an
obstacle in the way of the increasingly wide use of expansion
technology. The economic success of the present invention is a
credit to the inventor.
[0009] It is therefore the object of the invention to present an
expansion device as described above, by which, in spite of its very
complex geometric shape and friction conditions which are explained
in detail in the description, the service life and life expectancy
of the expansion device and especially of the spreading member of
the system is clearly prolonged.
[0010] The present invention provides a solution of the
aforementioned problem.
[0011] The aforementioned problem is completely solved by the
present invention. In particular, an expansion device as described
above is provided by which, despite its very complex geometric
shape and friction conditions, which are explained at length in the
detailed description, the service life of the expansion device and
especially of the spreading member of the system is definitely
lengthened.
[0012] As a result of further development of the invention, it is
especially advantageous if, either individually or in
combination:
[0013] the hard material consists of titanium nitride (TiN);
[0014] the coated surface of the spreading member is a conical
surface;
[0015] the spreading member is replaceably fastened to a driving
bar which is mounted in the bore of the base body;
[0016] the inside surfaces of the spreader jaws are configured as
sectors of a conical surface and are likewise coated with the hard
substance; and
[0017] the coating is made by a method from the group of the
physical (PVD), chemical (CVD) and physicochemical (PCVD) gas phase
depositions.
[0018] Examples of embodiments of the invention, their manner of
operation, and additional advantages are further explained below
with reference to FIGS. 1 to 4.
[0019] FIG. 1 is a partial axial section and an exploded
representation of the drive end of a first embodiment of an
expanding hand plier;
[0020] FIG. 2 is section of FIG. 1 on an enlarged scale and in a
complete axial sectional representation;
[0021] FIG. 3 shows an axial section taken through a tube end
enlarged and expanded with the device according to FIG. 2; and
[0022] FIG. 4 shows a section similar to FIG. 2 through a second
embodiment, but with a coated spreader cone interchangeable with a
driving bar on the housing side.
DETAILED DESCRIPTION
[0023] In FIG. 1 a basic body 1 is shown which forms a guide
housing to which is fastened a first hand lever 2 extending away in
a radial plane. Parts 1 and 2 can also be made as a contiguous
unit. The basic body 1 has two projecting fork parts 3 formed
therefor t, of which only the back fork is shown. A pivot pin 4
passes through the fork parts 3 and its axis vertically intersects
the system axis A-A. A second hand lever 5 is articulated on the
pivot pin 4 between the fork parts 3, which has a slot-like recess
5a of its own between the fork parts 3. Between the hand levers 2
and 5 is disposed a downstop 6, which consists of a threaded shaft
6a and a cap nut 6b with knurling 6c. The mounting of the downstop
6 can optionally be done in the hand lever 2 or in the base body
1.
[0024] The recess 5a is penetrated in turn by a pivot pin 7 which
can be rotated by turning the hand lever 5 around the pin 4. The
pivot pin 7 bears within the recess 5a a toggle lever 8 which acts,
through an additional pin 9 vertically intersecting the system axis
A-A, on a spreading member 10. The pivot pins 4, 7 and 9 are
disposed parallel to one another. The spreading member 10 contains
three sections, namely another fork-like section 10a in the wings
of which the axis pin 9 is journaled, a cylindrical section 10b,
and a spreading section 10c which causes the spreading action
described below. The spreading member 10 is guided in a bore 11 in
the basic body 1, which is coaxial with system axis A-A. The toggle
lever serves both for the expanding and for the positive withdrawal
of the spreading member which the spreader jaws follow in the
transverse direction.
[0025] The basic body 1 bears on an external screw thread 1a of its
own (FIG. 2), an adapter ring 12 coaxial with the system axis A-A,
having an external screw thread 12a and knurling 12b. Spreading
section 10c of the spreading member 10 which is shown as having a
cone shape in the figures, is axially movable out of the basic body
1 and adapter 12 under the effect of the toggle lever 8. Spreading
section 10c of spreading member 10 has an increasing or decreasing
cross-section corresponding to extension or retraction forces
applied thereto. Spreading section 10c may be of any suitable
shape, typically conical or pyramidal form, and cooperates with
essentially complementary contact faces of the jaws. Due to contact
with the pipe, spreading section 10c typically receives the most
wear of any part of the device. The downstop 6 prevents the pins 4,
7 and 9 from getting into an outstretched position in which the
stresses, of course, approach infinity.
[0026] An expansion head 13 can be replaceably threaded on the
basic body 1 and it, has a thimble ring 14 and a set of identical
sector-shaped spreader jaws 15 guided radially within the thimble
ring 14. By way of example, six spreader jaws 15 whose outer
surfaces in their outspread position assume the form of a
cylindrical surface with a diameter D, while radial gaps 16 are
opened between the spreader jaws. This diameter D determines the
inside diameter of a widened or expanded end of a pipe 17 (FIG. 3).
The adapter 12 can be omitted if the object is to provide the basic
body with a smaller expansion head 13. In such a case the expansion
head 13 is threaded directly onto the thread on the basic body
1.
[0027] Spreader jaws 15 have on the inside sector-shaped conical
surfaces which are only in a single and very specific position with
respect to one another in a common conical or envelope surface. The
reason for this lies in the process of the manufacture of the
workpiece, e.g., machining or precision casting. The workpiece is
afterward sawn through diametrically or axis-parallelly with
deliberate loss of material so that the above-mentioned radial gaps
16 are formed. Furthermore, the expansion heads 13 and the depth to
which they are threaded onto the basic body 1 are subject to
tolerances.
[0028] Spreading member 10, however, has but a single conical
surface. As a result, when an expansion is performed, positions on
the surface of the spreading member 10 have to be traversed
involving linear and edge pressures with infinite values.
Furthermore, when the pipe 17 is expanded, sliding movements also
occur which take place with increasing stresses, because as the
expanding material flows it solidifies due to the nature of the
material, which results in great wear on the spreading member
10.
[0029] As seen by viewing FIGS. 2 and 3 together, the conditions of
force and friction at the free ends of the spreading member 10 and
spreading jaws are especially critical. The greatest forces occur
at very small contact surfaces or lines. Here, furthermore, those
deformation forces from the area of transition 17b between the pipe
17 and the pipe end 17a add up at a point which is not supported by
the spreading jaws.
[0030] The result, however, is that the spreading member of the
prior art has to be replaced more often, resulting, in the case of
a one-piece spreading member, in complicated disassembly and
reassembly of the device.
[0031] The preceding part of this description applies to the state
of the art; the description of the invention follows.
[0032] A coating 18 is provided on the surface of the conical
section 10c of the spreading member 10, coating 18 is highlighted
by thick lines and is made preferably of titanium nitride (TiN).
Thus the service life of the expansion device is increased to a
multiple, which is of special importance since repair at the point
of use is, as a rule, impossible.
[0033] FIG. 2 now shows, continuing the above numbering, additional
details of the tool. Thus, it is shown that the coating of the
spreading member can extend also onto the cylindrical section 10b
of the spreading member. This has the further advantage that even
the wearing effect of the transverse forces produced by the toggle
lever 8 on the spreading member guiding means can be counteracted.
It is furthermore shown that the spreading jaws are guided by
rivets 19 in the thimble ring. The conversion of the axial motion
of the spreading member 10 to radial motions of the spreading jaws
is indicated by arrows.
[0034] FIG. 3 shows, as already indicated above, an axial section
taken through a pipe end 17a which has been widened or expanded
with the device shown in FIG. 2. An unexpanded pipe 17 is to be
inserted into this pipe end and soldered there. During the
diametrical enlargement the inside surface of the pipe 17 slides
due to the enlargement of the circumference onto the external
surfaces of the spreading jaws 15. It is, therefore, an additional
advantage to provide these external surfaces and, if desired, also
the inside surfaces of the spreading jaws, with the aforesaid hard
coating.
[0035] FIG. 4 shows an axial section similar to FIG. 2, but with
the difference that the spreading member 20 consists of a conical
part coated likewise to withstand attrition, which is threaded
replaceably by means of a threaded connection into a driving rod 22
on the housing side. Into the basic body 1 a transition piece 23 is
threaded by means of a threaded connection 24 and has a transition
piece 23 with a cylindrical recess 23a into which the end of the
spreading member 20 can be withdrawn. This embodiment has the
additional advantage that, if the driving rod 22 is made
accordingly, an uncoated spreading cone can be replaced with a
spreading member 20 coated pursuant to the invention, which also
permits retrofitting.
[0036] The spreading member 20 can be driven by a toggle lever not
shown here, or by a combination of rack and pinion, or by a cam. It
is also possible, however, to provide an electromechanical or
electrohydraulic driving device.
* * * * *