U.S. patent application number 12/202018 was filed with the patent office on 2009-03-05 for method and apparatus for producing stepped hollow shafts or stepped cylindrical hollow members by transverse rolling.
This patent application is currently assigned to ThyssenKrupp Bilstein Suspension GmbH. Invention is credited to Hans Dziemballa, Thomas Ficker, Andre Hardtmann, Mario Houska, Lutz Manke.
Application Number | 20090056400 12/202018 |
Document ID | / |
Family ID | 39942038 |
Filed Date | 2009-03-05 |
United States Patent
Application |
20090056400 |
Kind Code |
A1 |
Dziemballa; Hans ; et
al. |
March 5, 2009 |
METHOD AND APPARATUS FOR PRODUCING STEPPED HOLLOW SHAFTS OR STEPPED
CYLINDRICAL HOLLOW MEMBERS BY TRANSVERSE ROLLING
Abstract
The invention relates to a method and a device for transversely
rolling stepped hollow shafts or cylindrical hollow parts from a
pipe. The invention achieves the object of rolling stepped hollow
shafts of the most varied dimensions and also of greater lengths in
a flexible manner from a pipe using a small number of simple tools.
In accordance with the invention, the object is achieved by virtue
of the fact that rolling tools which can be radially advanced and
are disposed in a planet-like manner around the workpiece are used
to roll the contour of the transition from a central diameter in
one portion of the workpiece to the central diameter in the
adjacent portion by means of co-ordinated control of the radial
advance of the rolling tools and the axial feed of the workpiece,
and a mandrel head having an outer diameter which is adapted to the
smallest inner diameter of the two portions is disposed underneath
the rolling tools.
Inventors: |
Dziemballa; Hans; (Iserlohn,
DE) ; Manke; Lutz; (Hagen, DE) ; Houska;
Mario; (Sebnitz, DE) ; Ficker; Thomas;
(Langenberg, DE) ; Hardtmann; Andre; (Dresden,
DE) |
Correspondence
Address: |
CROWELL & MORING LLP;INTELLECTUAL PROPERTY GROUP
P.O. BOX 14300
WASHINGTON
DC
20044-4300
US
|
Assignee: |
ThyssenKrupp Bilstein Suspension
GmbH
Ennepetal
DE
|
Family ID: |
39942038 |
Appl. No.: |
12/202018 |
Filed: |
August 29, 2008 |
Current U.S.
Class: |
72/100 ;
72/96 |
Current CPC
Class: |
B21D 22/16 20130101;
B21H 1/18 20130101 |
Class at
Publication: |
72/100 ;
72/96 |
International
Class: |
B21D 19/00 20060101
B21D019/00; B21B 19/08 20060101 B21B019/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2007 |
DE |
10 2007 041 149.0 |
Claims
1) Method of transversely rolling stepped hollow shafts or
cylindrical hollow parts from a pipe with rolling tools which can
be advanced radially and are disposed in a planet-like manner
around the workpiece, axial feed between the workpiece and rolling
tools and a mandrel, wherein the rolling tools are used to roll the
contour of the transition from a central diameter in one portion of
the workpiece to the central diameter in the adjacent portion by
means of co-ordinated control of the radial advance of the rolling
tools and the axial feed, and a mandrel head having an outer
diameter which is adapted to the smallest inner diameter of the two
portions is disposed underneath the rolling tools.
2) Method as claimed in claim 1, wherein the rolling tools comprise
a cylindrical smoothing shoulder and a conical forming
shoulder.
3) Method as claimed in claim 1, wherein in addition to the
clearance required for the axial mobility of the mandrel head in
the workpiece, a flexing clearance of at least 0.1 mm is provided
between the outer diameter of the mandrel head and the
corresponding smallest inner diameter of the workpiece.
4) Method as claimed in claim 1, wherein the workpiece is
externally supported against transverse forces at least one site by
support rollers.
5) Method as claimed in claim 1, wherein the workpiece is turned
when changing from one portion to the next.
6) Method as claimed in claim 1, wherein the rolling tools are
turned when changing from one portion to the next.
7) Method as claimed in claim 1, wherein prior to rolling a portion
the workpiece is heated in the region of the next forming
portion.
8) Device for transversely rolling stepped hollow shafts or
cylindrical hollow parts from a tube with rolling tools which can
be radially advanced and are disposed in a planet-like manner
around the workpiece, devices for producing an axial feed between
the workpiece and the rolling tools and a mandrel, wherein the
control of the radial advance of the rolling tools and the control
of the axial feed between the rolling tools and the workpiece are
coupled together by a program control and a mandrel head having the
outer diameter which is adapted to the smallest inner diameter of
the two portions is disposed approximately below the rolling
tools.
9) Device as claimed in claim 8, wherein the rolling tools comprise
a cylindrical smoothing shoulder and a conical forming
shoulder.
10) Device as claimed in claim 9, wherein the free edge of the
smoothing shoulder is rounded off with a radius r of 0.5 to 3
mm.
11) Device as claimed in claim 8, wherein the mandrel consists of a
mandrel head and a mandrel shaft which is reduced in diameter with
respect to the mandrel head.
12) Device as claimed in claim 11, wherein the mandrel head length
corresponds approximately to the axial width of the rolling
tools.
13) Device as claimed in claim 11, wherein the mandrel head is
cylindrical.
14) Device as claimed in claim 8, wherein in addition to the
clearance required for the axial mobility of the mandrel head in
the workpiece, a flexing clearance of at least 0.1 mm is provided
between the outer diameter of the mandrel head and the
corresponding smallest inner diameter of the workpiece.
15) Device as claimed in claim 8, wherein the workpiece is mounted
between support rollers which can be radially advanced.
16) Device as claimed in claim 15, wherein in each case three
support rollers are disposed in one plane in a planet-like manner
around the workpiece and these three support rollers are mounted in
a stand.
17) Device as claimed in claim 16, wherein the stand is disposed in
an axially displaceable manner in a guide (11) lying in parallel
with the workpiece axis.
18) Device as claimed in claim 17, wherein at least one stand also
travels at the axial speed of the workpiece part, to which it is
allocated.
19) Device as claimed in claim 18, wherein the travelling stand is
allocated an axial drive and the control thereof is connected to
the program control.
20) Device as claimed in claim 16, wherein at least one stand is
disposed in a stationary manner in the vicinity of the rolling
tools.
21) Device as claimed in claim 8, wherein the rolling carriage (5)
is axially displaceable.
Description
[0001] The invention relates to a method and a device for
transversely rolling stepped hollow shafts or cylindrical hollow
parts from a pipe. In particular, pipe blanks for manufacturing
divided and undivided pipe stabilisers for motor vehicles can be
produced in an advantageous manner. They are characterised by
virtue of the fact that they have variable diameters and wall
thicknesses in regions over their longitudinal axis, which on the
one hand leads to a reduction in component weight and on the other
hand permits optimal usage of the installation space available.
Furthermore, the load-adapted cross-sections permit a uniform
tension distribution and thus optimal usage of the material used.
When utilising the invention for the pipe-stabiliser application,
further advantages can be achieved by eliminating wall thickness
fluctuations in the pipe used and by improving the material quality
of the pipe surfaces by stretching any decarburization regions
present and so-called "phosphate edges".
[0002] Various solutions for transversely rolling stepped hollow
shafts or hollow bodies or cup-shaped hollow parts over a mandrel
are already known.
[0003] In accordance with DD 99 521 A or even DE 199 05 038 A1, the
blank is axially compressed between wedge-shaped tools with inner
forming tools at the same time during the rolling process and is
rolled out starting from the centre to form a double-sided
cup-shaped hollow body. The outer contour of the inner forming
tools (mandrels) corresponds to the inner contour of the hollow
body.
[0004] In the broadest sense, the solutions for rolling bearing
seats and outer toothings (EP 0 248 983 A1 or DE 199 58 343 A1) or
inner toothings (e.g. U.S. Pat. No. 5,765,419) are classified in
this group of transverse rolling with profiled mandrels or
transverse rolling tools.
[0005] Longer hollow shafts are reduced substantially only in wall
thickness on a continuously cylindrical mandrel, either
continuously (WO 02/55226 A1 or DE 20 04 444 C3) or in sections (DE
101 15 815 A1). The last solution is a type of transverse rolling
of a stepped hollow shaft. However, only the outer diameter of the
hollow shaft is stepped in sections. The inner diameter is
unchanged over its entire length and corresponds to the outer
diameter of the mandrel.
[0006] In order to produce a pipe-shaped stabiliser for motor
vehicles by forming, rotary swaging can be utilised. However, it is
not particularly productive in spite of high technical outlay.
[0007] It is the object of the invention to provide a solution with
which stepped hollow shafts or cylindrical hollow parts with the
most varied dimensions and also longer lengths can be rolled in a
flexible manner from a pipe using a small number of simple
tools.
[0008] The object is achieved in accordance with the invention by
virtue of the fact that by means of rolling tools which can be
radially advanced and are disposed in a planet-like manner around
the workpiece the contour of the transition from a central diameter
in one portion of the workpiece to the central diameter in an
adjacent portion is rolled by means of co-ordinated control of
radial advance of the rolling tools and axial feed of the workpiece
and a mandrel head having an outer diameter which is adapted to the
smallest inner diameter of the two portions is disposed underneath
the rolling tools.
[0009] It has been found that these transitions can also be rolled
without the assistance of a mandrel whose outer profile corresponds
to the inner profile of the transition. At the beginning of a
transition from a large central diameter to a smaller one, the
outer periphery of the mandrel head does not lie against the inner
periphery of the workpiece at the instantaneous forming site. Only
towards the end of this transition and during rolling of continuous
portions having a constant inner diameter does the mandrel perform
its typical function. For this purpose, it is disposed underneath
the rolling tools.
[0010] Tests have demonstrated that it is possible to produce a
pipe-shaped stabiliser for motor vehicles with two regions, which
are stepped on the end side, and one long central part, which is
reduced in diameter and wall thickness, from a pipe having a length
of 1.6 m, ca. 22 mm outer diameter and a wall thickness of ca. 4
mm. The process is very productive. It is fundamentally possible to
produce the stabiliser in a clamping system.
[0011] The friction between the workpiece and the mandrel head is
restricted to a minimum. This is achieved on the one hand by a
relatively short mandrel head and on the other hand by means of a
clearance fit, which is typical for displacement, between the outer
and inner diameters of the mandrel head and the workpiece.
Moreover, in addition to this clearance a further clearance of at
least 0.1 mm is preferably provided which promotes forming and is
to be defined as flexing clearance.
[0012] The forming procedure is further assisted by virtue of the
fact that the workpiece is mounted in support rollers.
[0013] Preferably, three support rollers are disposed in each case
in one plane in a planet-like manner around the workpiece and are
mounted in a stand. They can be radially advanced onto the
workpiece. The stands are displaceable in parallel with the
workpiece axis. At least one stand is disposed in a stationary
manner in proximity to the rolling tools. Particularly in the case
of longer workpieces, at least one further stand is provided which
preferably moves simultaneously with the workpiece end, to which it
is allocated. Overall, the support rollers serve to absorb the
"transverse forces" which result from the forming procedure and
which are not neutralised by the rolling tools and the active part
of the rolling mandrel. Such remaining transverse forces also occur
primarily during rolling of the transitions. Moreover, they support
the weight of the workpiece parts which protrude over the active
(engaged) part of the rolling mandrel.
[0014] Preferably, the forming procedure is performed using rolling
tools which have a smoothing shoulder and a forming shoulder,
wherein preferably the free edge of the smoothing shoulder is
rounded off with a radius of 0.5 to 3 mm. Primarily, the short
transitions are rolled with this edge. In order to roll transitions
which on one portion are short on both sides, the workpiece is
preferably turned.
[0015] Portions having greater wall thicknesses and consisting of
materials which are difficult to form (e.g. high-tensile steels)
are heated prior to rolling.
[0016] Further features in accordance with the invention are
described in the claims and in the exemplified embodiment.
[0017] The invention will be demonstrated hereinunder in several
exemplified embodiments. In the drawings,
[0018] FIG. 1 shows a plan view of a device in accordance with the
invention,
[0019] FIG. 2 shows an enlarged section of FIG. 1,
[0020] FIG. 3 shows the section "Z" of FIG. 2,
[0021] FIGS. 4a to 4h show the stepwise formation of a pipe into a
hollow shaft.
[0022] The device for transversely rolling stepped hollow shafts
from a pipe as shown in FIG. 1 has an approximately cross-shaped
outline in the plan view shown in FIG. 1. A rolling spindle drive
4, a rolling mandrel bearing 7, a rolling mandrel 8, the workpiece
1, support rollers 9, a clamping device 6 and an axial rolling
carriage 5 are disposed in parallel with the axis of the workpiece
1 (the pipe to be formed or the resulting hollow shaft) from right
to left.
[0023] Rolling tools 3 are provided at the forming site. They are
mounted in radial rolling carriages 2. These rolling carriages can
be displaced transversely with the respect to the workpiece 1. The
rolling tools 3 are radially advanced therewith. For this purpose,
they have a dedicated, preferably hydraulic, drive. The rolling
tools 3 are driven about axes in parallel with the workpiece axis
by means of the rolling spindle drive 4. During forming, the
workpiece 1 is pulled with the axial rolling carriage 5 to the left
and at the same time is rotated with the rolling tools 3. The
clamping device 6 for clamping the workpiece 1 is located on the
axial rolling carriage 5. The forces for pulling the workpiece 1
are applied against the rolling tools 3 by two hydraulic pistons
which are disposed in a pivotable manner in the axial rolling
carriage 5.
[0024] As shown more clearly in FIG. 2, a carriage guide 11 is
disposed underneath the workpiece 1. Stands 12 which each have
three support rollers 9 are disposed in a displaceable manner on
this carriage guide. The support rollers 9 surround the workpiece 1
in a planet-like manner and can be advanced radially onto the
respective outer diameter of the workpiece 1. The stand 12a in
direct proximity to the rolling tools 3 is stationary. The stands
12b which are further away from the rolling tools 3 move with the
workpiece 1 (see the double arrow under the stands 12b). Their
spaced interval from the rolling tools 3 changes continuously
during forming. The movement direction of the workpiece 1 is shown
on the left-hand side by an arrow.
[0025] Any remaining transverse forces applied to the workpiece 1
immediately adjacent to the forming site and in each case at the
furthest spaced interval from the forming site are absorbed by the
support rollers 9.
[0026] As shown in FIG. 3, the free edge of the smoothing shoulder
of the rolling tool 3 is rounded off with a radius r.
[0027] FIGS. 4a to 4h illustrate the sequence of forming a hollow
shaft which has multiple steps in its central part.
[0028] In each case, the workpiece 1 is clamped in the clamping
device 6 and is pulled the distance of a feeding path s.sub.ax. The
rolling tools 3 are advanced radially by the distance s.sub.r. The
respective path length is indicated by the length of the arrow. The
direction is given by + and -. During axial feeding, + in the
drawing denotes the movement to the left (in the direction of
tension of the clamping device 6). The radial advance of the
rolling tools in the direction of the workpiece axis is denoted by
+, and the opposite direction is denoted by -. Rolling mandrels 8a
to 8c which have an outer diameter corresponding to the respective
smallest inner diameter of the workpiece are used. The mandrel head
has not been illustrated.
[0029] In FIG. 4a, the workpiece is still the original pipe. It is
already clamped. Rolling tools 3 and rolling mandrels are not in
engagement.
[0030] In FIG. 4b, a first transition from the previous diameter to
a smaller central diameter is rolled. The rolling tools 3 are
advanced with +s.sub.r. The workpiece 1 is pulled the distance of a
small axial feed path. The large diameter mandrel 8a is disposed
underneath the forming site. At the beginning of the transition,
the inner periphery of the workpiece 1 is not yet supported by the
mandrel 8b.
[0031] In the next step (FIG. 4c), the position of the rolling
tools 3 is no longer radially adjusted. The workpiece is pulled the
distance of a relatively long feed path (see arrow size of
+s.sub.ax).
[0032] In the steps 4d and 4e (cf. FIGS. 4d and 4e), further
step-formation similar to that performed in steps 4b and 4c is
carried out but with the medium diameter rolling mandrel 8b.
[0033] FIGS. 4f and 4g illustrate on the one hand a repetition of
the above-described forming steps with the smallest diameter
rolling mandrel 8c. A feature of FIG. 4g is that a conical
transition is rolled. A small axial feed +s.sub.ax is coupled with
a negative small advance -s.sub.r of the rolling tools. The rolling
mandrel is still located underneath the rolling tools 3 but at the
instantaneous forming site is still only in radial proximity to the
inner periphery of the workpiece 1.
[0034] In the final stage, FIG. 4h, the hollow shaft is completely
rolled. The rolling tools are disengaged.
[0035] In practical tests, a hollow shaft was rolled from an
approximately 1.5 m long pipe consisting of 34MnB5 having an outer
diameter of about 25 mm and an wall thickness of about 4 mm. In a
central portion (ca. 400 mm long) and at the two ends (ca. 200 mm
long), the pipe was stepped by about 2 mm at the outer diameter.
The wall thickness of the stepped parts was reduced by about 1 mm.
The forming portions were heated. The average rolling temperature
was 600.degree. C.
* * * * *