U.S. patent application number 11/287203 was filed with the patent office on 2006-05-04 for method of producing individualized vehicle parts, particularly individualized vehicle body skin parts consisting of series-produced vehicle body skin parts, as well as vehicle body skin parts manufactured by this method.
This patent application is currently assigned to Bayerische Motoren Werke Aktiengesellschaft. Invention is credited to Stefan Bartscher, Maik Hammer, Gero Kempf, Tobias Loebel.
Application Number | 20060090530 11/287203 |
Document ID | / |
Family ID | 33482249 |
Filed Date | 2006-05-04 |
United States Patent
Application |
20060090530 |
Kind Code |
A1 |
Hammer; Maik ; et
al. |
May 4, 2006 |
Method of producing individualized vehicle parts, particularly
individualized vehicle body skin parts consisting of
series-produced vehicle body skin parts, as well as vehicle body
skin parts manufactured by this method
Abstract
A method for producing vehicle parts is provided, particularly
shell parts for vehicles, according to which a three-dimensionally
preformed semi-finished or finished standard part, especially a
standard shell part, is produced for a serially manufactured
vehicle type. An individualized part is then produced from the
preformed standard part by subsequently embossing a
three-dimensional contour into the standard part by use of a
mandrel-type reshaping tool which is pressed against the standard
part from one side while being displaced relative to the standard
part.
Inventors: |
Hammer; Maik; (Eisenach,
DE) ; Kempf; Gero; (Taufkirchen, DE) ;
Bartscher; Stefan; (Muenchen, DE) ; Loebel;
Tobias; (Chemnitz, DE) |
Correspondence
Address: |
CROWELL & MORING LLP;INTELLECTUAL PROPERTY GROUP
P.O. BOX 14300
WASHINGTON
DC
20044-4300
US
|
Assignee: |
Bayerische Motoren Werke
Aktiengesellschaft
Muenchen
DE
80809
|
Family ID: |
33482249 |
Appl. No.: |
11/287203 |
Filed: |
November 28, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP04/01403 |
Feb 14, 2004 |
|
|
|
11287203 |
Nov 28, 2005 |
|
|
|
Current U.S.
Class: |
72/75 ;
72/125 |
Current CPC
Class: |
B21D 22/26 20130101;
B21D 22/18 20130101 |
Class at
Publication: |
072/075 ;
072/125 |
International
Class: |
B21D 17/04 20060101
B21D017/04 |
Foreign Application Data
Date |
Code |
Application Number |
May 28, 2003 |
DE |
103 24244.9 |
Claims
1. A method of producing a vehicle part, the method comprising the
acts of: producing, from a starting material, a three-dimensional
preformed serial part for a vehicle model manufactured in a series
production, the preformed serial part being at least one of a
semi-finished and finished serial part for the vehicle model
manufactured in the series production; pressing a mandrel-type
forming tool against one side of the preformed serial part and
simultaneously moving the mandrel-type forming tool relative to the
serial part to impress an additional three-dimensional contour in
the serial part to produce an individualized part from the serial
part.
2. The method according to claim 1, wherein the individualized
vehicle part produced is at least one of a vehicle body skin part
and a series-produced vehicle body skin part.
3. The method according to claim 2, wherein the starting material
is a metal sheet, and the serial part, as well as the body skin
part to be produced therefrom, each are sheet metal parts.
4. The method according to claim 2, wherein the starting material
is a plastic material, and the serial part, as well as the body
skin part to be produced therefrom, each are plastic parts.
5. The method according to claim 2, wherein the starting material
is a thermoplastic material.
6. The method according to claim 4, wherein the starting material
is a thermoplastic material.
7. The method according to claim 2, wherein the series-produced
body part is held by a holding device in edge areas of the
series-produced body part during deforming by the mandrel-type
forming tool.
8. The method according to claim 7, wherein the holding device has
a plurality of holding points.
9. The method according to claim 8, wherein the holding points are
each formed by a suction-cup-type holding element, which hold the
serial part via a vacuum.
10. The method according to claim 7, wherein the serial part is
held during deforming by the mandrel-type forming tool exclusively
in its edge areas by the holding device and is neither supported
nor otherwise held in the component areas situated in-between.
11. The method according to claim 7, wherein the serial part is
held by the holding device during deforming by the mandrel-type
forming tool and, in a component area situated in-between, is
supported at least at one point by a counterholder, which is
arranged on the side of the serial part situated opposite the
mandrel-type forming tool.
12. The method according to claim 11, wherein the counterholder is
a die-type component which acts as a negative mold with respect to
the three-dimensional contour to be produced.
13. The method according to claim 1, wherein the mandrel-type
forming tool has a smooth, convexly curved tool tip.
14. The method according to claim 1, wherein the tool tip of the
mandrel-type forming tool is formed by a rotatably disposed ball,
which rolls on the serial part during the working of the serial
part.
15. The method according to claim 1, wherein the mandrel-type
forming tool has an adjustable tool tip whose width transversely to
the moving direction of the mandrel-type forming tool is changed
relative to the serial part during the working operation.
16. The method according to claim 1, wherein the mandrel-type
forming tool is heated during deforming of the serial part at least
in an area of the tool tip.
17. The method according to claim 1, wherein the serial part is
heated by a heat source during deformation.
18. The method according to claim 1, wherein the forming tool is
rotated about a longitudinal axis of the forming tool during
deformation of the serial part.
19. The method according to claim 1, wherein the forming mandrel is
oscillated about an longitudinal axis of the forming mandrel during
deformation of the serial part.
20. The method according to claim 1, wherein design-relevant,
line-type characteristic contours are impressed into the serial
part by use of the mandrel-type forming tool.
21. The method according to claim 1, wherein the serial part is a
pressed piece, which is produced by using a mold-type tool.
22. The method according to claim 1, wherein the serial part is a
sheet metal part produced by deep drawing.
23. The method according to claim 1, wherein a contour already
existing in the serial part is redrawn or deepened by reworking
with the mandrel-type forming tool.
24. The method according to claim 1, wherein the serial part is one
of a front opening hood, a tailgate, a door, a side part, a fender,
or a roof.
25. The method according to claim 1, wherein the mandrel-type
forming tool is arranged on an arm of a robot.
26. The method according to claim 1, wherein the mandrel-type
forming tool is part of a CNC machine tool.
27. The method according to claim 1, wherein, during working of the
serial part, the mandrel-type forming tool rotates about its
longitudinal axis, whereby a drilling-friction-type contact occurs
between a tip of the forming mandrel and the serial part.
28. The method according to claim 1, wherein, during deformation,
the serial part is held such that its geometry in its edge areas is
not changed with respect to its starting condition.
29. The method according to claim 28, wherein connection
measurements or gap measurements, which occur during a later
installation into a vehicle body shell, do not change with respect
to the serial part in its starting condition.
30. The method according to claim 1, wherein the three-dimensional
contour to be additionally produced in the serial part is produced
by a one-time moving of the mandrel-type forming tool in a single
pass.
31. The method according to claim 1, wherein the three-dimensional
contour to be additionally produced in the serial part is produced
by a repeated moving and incremental application of the
mandrel-type forming tool.
32. The method according to claim 31, wherein the mandrel-type
forming tool is applied from one reworking pass to the next
reworking pass essentially perpendicularly with respect to the
serial part, so that the contour is deepened from one reworking
pass to the next.
33. The method according to claim 31, wherein, from one reworking
pass to the next reworking pass, the mandrel-type forming tool is
applied essentially transversely to the moving direction of the
forming tool, so that the contour is widened from one reworking
pass to the next.
34. The method according to claim 32, wherein, from one reworking
pass to the next reworking pass, the mandrel-type forming tool is
applied essentially transversely to the moving direction of the
forming tool, so that the contour is widened from one reworking
pass to the next.
35. A vehicle body skin part which is produced from a serial part
according to the method of claim 1.
36. A vehicle body skin part according to claim 35, wherein the
serial part is made of sheet metal.
37. The vehicle body skin part according to claim 35, wherein the
serial part is made of a plastic material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The application is a continuation of PCT Application No.
PCT/EP2004/01403 filed on Feb. 14, 2004 which claims priority to
Germany Application 10324244.9-14 filed on May 28, 2003.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] The present invention relates to a method of producing
vehicle body skin parts, as well as to a vehicle body skin part
produced by this method.
[0003] Vehicle body parts, such as engine hoods, roofs, fenders,
side panels, trunk lids, etc. are normally produced by deep drawing
from flat starting metal sheets. As known, the tools of
deep-drawing presses are very expensive and can, therefore, be used
economically only for relatively large piece numbers. In addition,
the sheet geometries which can be produced by means of conventional
deep-drawing presses are limited with respect to their complexity.
However, vehicle designers demand increasingly broader design
ranges, which demands cannot always be met by means of conventional
deep-drawing tools. Modern vehicle designs are characterized, for
example, by transitions between convex and concave component
sections, as well as by greatly accentuated characteristic lines or
edges with partially very narrow radii of curvature. This already
occasionally limits manufacturing possibilities when conventional
deep-drawing methods are used.
[0004] The so-called "dieless forming technology", which is known,
for example, from U.S. Pat. No. 6,216,508 B1, uses a completely
different approach. As the name indicates, the metal sheet forming
takes place in a "dieless" manner; that is, without a mold, in the
conventional sense. In the case of the dieless forming, as
described in U.S. Pat. No. 6,216,508 B1, a flat sheet metal blank
is clamped in its edge area into a holding device. For the forming
process, a forming mandrel is used, which is arranged essentially
perpendicularly with respect to the clamped-in sheet metal blank
and may be moved in the X- and Y-direction. An advancing movement
in the Z-direction is possible, either by moving the advancing
mandrel or by perpendicularly moving the sheet metal blank clamped
in the holding device.
[0005] The basic principle of dieless forming, as known from U.S.
Pat. No. 6,216,508 B1, consists of the fact that a flat sheet metal
blank, that is, a metal sheet which is not preformed, is formed
into a three-dimensional component by use of the forming mandrel.
For this purpose, the forming mandrel is pressed against the sheet
metal blank. By meandering or spirally moving along the entire
sheet metal blank, a three-dimensional sheet metal part can be
produced by an incremental advancing of the forming mandrel. In
comparison to conventional deep-drawing methods, it is an advantage
of this dieless forming method that also very complex component
geometries may be produced.
[0006] However, a significant disadvantage of the dieless forming
method described in U.S. Pat. No. 6,216,508 B1 is the very long
production time. When a large complex sheet metal part, such as a
body part for a vehicle, is to be produced from a flat sheet metal
blank by this dieless forming method, it is extremely time
consuming. In the case of the dieless forming method described in
U.S. Pat. No. 6,216,508 B1, the forming mandrel has to move in a
meandering or spiral manner along the entire sheet metal blank from
one contour to the other, which takes a very long time in
comparison to conventional deep drawing. The production of a
vehicle body part, for example, of an engine hood, takes a few
seconds or fractions of seconds by means of a conventional
deep-drawing process. If one were to try to produce such a vehicle
body part by the dieless forming method as described in U.S. Pat.
No. 6,216,508 B1, this would take several minutes, depending on the
component, even up to several hours.
[0007] Another problem occurring during the production of complete
components by use of the dieless forming method is the fact that
very considerable changes occur in the crystal structure of a metal
sheet during the incremental deformation of the metal sheet, that
is, during a "track-by-track" deformation. Tests have shown that
often considerable roughnesses occur in the case of more complex
vehicle body parts, which are produced from flat, that is, not
preformed, starting metal sheets completely by "dieless forming".
The roughnesses of the component surface are frequently so
extensive that, as a rule, the sheet metal part cannot be painted
immediately after its production but has to be reworked at high
expenditures before painting; for example, by a leveling-out and
grinding of the surface or by other "smoothing work". On the whole,
the dieless forming technology has been confronted by numerous
unsolved problems. The dieless forming process has, therefore, not
been successful for use in motor vehicle construction, particularly
in the series production of motor vehicle parts.
[0008] As mentioned above, there is the dilemma that arbitrarily
complex motor vehicle designs cannot be produced by means of
conventional deep-drawing methods. Another problem consists of the
fact that, because of the expensive tools, deep-drawing methods are
economical only in large-scale productions, that is, starting at
certain minimum batch sizes.
[0009] Particularly in the case of premium vehicles, many customers
have very specific equipment-related wishes which cannot always be
satisfied by means of the conventionally offered special equipment
program. Even today, many vehicle manufacturers offer so-called
"individual or small-series vehicles" for individual vehicle types.
However, with respect to the vehicle body area, these individual or
small-series vehicles frequently do not differ, or differ only a
little from, the normal production vehicles. The reason is that an
individual design of the vehicle body skin so far has not been
possible in a cost-effective manner. Today, the "individualization"
of such vehicles in comparison to conventional vehicles is
frequently limited to the offer of unusual materials for the
interior as well as to unusual colors.
[0010] An aspect of the invention is to provide a method by which
components, particularly, skin components for vehicles, and
particularly those for small-series or miniseries vehicles, may be
produced individually and, at the same time, cost-effectively
corresponding to the customer's wishes, or to provide a body skin
part which meets these requirements.
[0011] The present invention meets these needs by providing a
method for producing vehicle body parts, wherein a
three-dimensionally preformed, semifinished or finished serial part
is produced from a starting material for a vehicle model
manufactured in a series production. An individualized part is
produced from the preformed serial part by way of a mandrel-type
forming tool, which is pressed from one side against the serial
part and is simultaneously moved relative to the serial part in
order to additionally impress a three-dimensional contour in the
serial part. Advantageous embodiments and further developments of
the invention are described and claimed herein.
[0012] As mentioned above, the basic principle of the dieless
forming method is known per se and is described in the initially
mentioned U.S. Pat. No. 6,216,508 B1. It is explicitly pointed out
that the entire technical content of U.S. Pat. No. 6,216,508 B1 is
to be the object of the present patent application even if the
present invention is not aimed at the method described in U.S. Pat.
No. 6,216,508 B1. Thus, if required, it should be possible to fall
back in the examination procedure of the present patent application
on all characteristics disclosed in U.S. Pat. No. 6,216,508 B1
alone or in combination with other characteristics of U.S. Pat. No.
6,216,508 B1 or of the present text. The dieless forming method per
se therefore does not have to be explained in all details in the
present text. Accordingly, applicants expressly incorporate by
reference the content of U.S. Pat. No. 6,216,508.
[0013] Although the following description of the invention
primarily relates to serial skin parts made of sheet metal, it is
explicitly pointed out that the invention is not limited to
workpieces made of sheet metal. The invention can basically be used
for all types of components, such as structural parts. The
invention is also not limited to components made of sheet metal. On
the contrary, it is also possible to use the invention for
workpieces made of plastic material, particularly parts made of a
thermoplastic material or other materials.
[0014] The present invention primarily consists of meeting
individual customers' wishes in that a "serial skin part" is
"individualized" by use of a finishing using a "forming tool" which
is pressed against the serial skin part and is moved relative to
the serial skin part.
[0015] A significant difference with respect to U.S. Pat. No.
6,216,508 B1 consists of the fact that the reworking takes place on
a "preformed serial part", which in its entirety is specifically
not produced according to the method described in U.S. Pat. No.
6,216,508 B1, but by another production method, such as deep
drawing. Only a partial area, or several partial areas, of this
preformed serial part are reworked by use of the above-mentioned
forming tool, but not the entire serial part.
[0016] Before the installation into a vehicle body shell, the
preformed "serial part", which may already be a semifinished or
finished vehicle body shell part, is additionally impressed by
means of a "reworking" with a "geometry" or "contour" deviating
from conventional series-produced vehicles. In this manner,
characteristic lines, writing patterns, or the like, may be
impressed into semifinished or finished vehicle body shell parts,
such as front opening hoods, tailgates, doors, side panels,
fenders, roofs, etc. In addition, characteristic lines or component
edges already present in the serial skin part may be redrawn or
deepened and therefore made to be more pronounced than would be
possible, or is possible, in the case of the serial skin parts used
for conventional series-produced vehicles. By way of such a
reworking by using a forming tool, an infinite number of design
modifications may be produced from conventional serial skin parts,
specifically in a manner which is cost-effective to a degree never
before thought possible. In that serial-like vehicles are offered
in small series or as individual vehicles, the customers' wishes
for an individualization existing particularly in the case of
high-priced vehicles may be met more easily. As a result of such a
differentiation, vehicles obtain an individual "design character"
and, therefore, are clearly visually different from other vehicles
of the respective vehicle type.
[0017] Tests have shown that, in contrast to the production of
complete sheet metal parts from flat starting metal sheets by
dieless forming, as described in U.S. Pat. No. 6,216,508 B1, in the
case of only a reworking of already "preformed" sheet metal parts
(serial skin parts), the initially described surface problems do
not occur. The reason is that, particularly in the case of a
"slight" reworking, for example, when producing characteristic
lines or when accentuating already present component structures,
only a relatively slight change occurs in the crystal structure of
the metal sheet. The surface quality in the area of such
characteristic lines, which were produced by a reworking according
to the invention, is so good that a high-expenditure surface after
treatment, as required in the state of the art, is superfluous. The
component may therefore be subjected to the conventional painting
process immediately after the reworking.
[0018] The invention is explicitly not limited to the production of
skin parts for small-series vehicles or individual vehicles. In the
course of their product service life, vehicles are frequently
subjected to a "model update"--a so-called "facelift". Within the
scope of model updates, the skin parts of the vehicles are
occasionally also updated to a certain extent or made more
attractive. Up to now, it has been necessary in this case to
procure new pressing tools or correspondingly adapt existing
pressing tools to the new design, which is always connected with
very high tool costs. By use of the method explained in detail
below, it now becomes possible to update or rework vehicle skin
parts produced by means of the "old" pressing tools. In this
manner, additional characteristic lines, elevations, etc. may be
impressed into the "old" skin parts, which permits a "model
facelift" at significantly lower costs than previously.
[0019] Another significant advantage of the invention consists of
the fact that a corresponding "reworking station" may be integrated
without any problem into an existing production line. Serial parts
which are intended for individual vehicles or for individualized
vehicles are reworked in the "reworking station". Serial parts for
conventional series-produced vehicles pass through the reworking
station without being reworked. Naturally, a reworking according to
the invention is also contemplated outside the production line in
separate working stations.
[0020] As mentioned above, the basic principle of the method
according to the invention consists of impressing a
three-dimensional contour into a sheet metal part by use of a
forming tool which may, for example, have a mandrel-type design. In
the following, the forming tool is also called a "forming mandrel"
which, however, should not be understood to be limiting with
respect to a certain tool shape.
[0021] During the reworking of a component, the "forming mandrel",
by means of its end, which may be constructed, for example, as a
point or as a rounded tip, is pressed against the component.
Simultaneously, the component and the forming mandrel are displaced
relative to one another. As a result, corresponding to the geometry
of the end of the forming mandrel and as a function of the contact
pressure force as well as the "clamped-in or supported condition"
of the component to be worked, a "shaping-in or shaping-out" or
very generally a three-dimensional contour is produced. The contour
to be produced may, for example, have the shape of a groove, of an
elevation, or another shape.
[0022] The invention comprises a "one-curve reworking" as well as,
to a certain extent, an "incremental reworking".
[0023] During the "one-curve reworking", the forming tool used is
applied to the component to be reworked, is pressed against the
component, and is subsequently moved in a single movement relative
to the component. The reworking therefore takes place in that the
forming tool is moved "in one pass", whereby the desired geometry,
for example, an elevation, a characteristic line, or the like, is
impressed into the component.
[0024] In contrast, during the "incremental reworking", the forming
tool is moved several times relative to the component to be
reworked and is applied incrementally. A geometry, such as an
elevation, produced in a first reworking operation, may be
deepened, that is, be made more pronounced, by a corresponding
application movement--essentially perpendicular to the component to
be reworked--in another reworking operation. As an alternative or
in addition, a geometry, such as an elevation, produced by a first
reworking operation may be "broadened" and in this manner made more
pronounced by a slight displacement of the forming tool relative to
the component and essentially transversely to the moving direction
of the first reworking operation. By a meandering guidance of the
forming mandrel or by a repeated moving-along on "reworking
trajectories" situated closely side-by-side, larger
three-dimensional shaped-out sections, such as pronounced intake
channels, of the "power domes" of an engine hood, or very generally
structural elevations may also be produced.
[0025] However, as mentioned above, the invention is not directed,
as in U.S. Pat. No. 6,216,508 B1, to the production of complete
vehicle body parts by the dieless forming method. This would be
much too time-consuming and uneconomical. On the contrary, the
present invention consists of the "additional" working or
individualization of individual areas of semifinished or finished
components, particularly body shell parts.
[0026] In this context, "finished" means that the body shell part
would be finished for a painting operation, but before that
painting operation is reworked in one component area or in several
component areas. However, in principle, it is also contemplated to
"individualize" or differentiate already finished painted serial
body skin components by a reworking according to the invention.
"Semifinished" means that, after the reworking according to the
invention, the body shell part is reworked further; for example, by
after treating the surface, trimming or edging of component edges,
drilling of holes, threading, or the like, and is painted only
subsequently.
[0027] Before the reworking according to the invention, the serial
skin part or the body shell part is clamped into a holding device.
The holding device may, for example, be formed by a plurality of
individual "holding points" or "holding sections". It is also
contemplated to use suction-cup-type holding elements.
Suction-cup-type holding elements have the advantage that the
danger of damage to the body skin sheet metal part, particularly
the danger of damaging the component surface, during the
clamping-in and during the working is reduced because the workpiece
is not clamped between two holding elements, but rather is fixed by
a vacuum.
[0028] Preferably, the workpiece, that is, the serial body skin
part, is clamped in before the reworking in such a manner that its
geometry in the edge area is not changed by the reworking. In other
words, connection measurements or gap measurements, which occur
during the later installation of the body skin parts into a vehicle
body, should not be changed by the reworking in comparison to the
"normal series-produced vehicle".
[0029] Depending on the complexity of the component geometry to be
produced "additionally", during the reworking, the series-produced
body skin part may be held either exclusively by means of a holding
device, for example, in its edge area; in the case of more complex
component geometries or in the case of three-dimensional contours,
which have a considerable surface gradient, particularly in the
case of relatively "sharp" edges, one or more counterholders or
supported elements may be used. Such counterholders or supporting
elements are pressed from the side situated opposite the forming
mandrel, that is, "from behind" against the series-produced body
skin part. Edge-shaped or curved "supporting elements" may be used
as the counterholders. As an alternative thereto, the counterholder
may also have the shape of a "die", which has a "negative shape"
corresponding to a three-dimensional contour to be produced.
However, the use of such a counterholder is not a necessity.
[0030] If two counterholders are used, one counterholder is
preferably arranged in the moving direction of the forming tool on
the left beside the geometry to be produced, and the other
counterholder is preferably arranged on the right beside the
geometry to be produced. Even the selection or the change of the
mutual spacing of the counterholders and the lateral distance of
the counterholders from the geometry to be produced can influence
the shape of the geometry to be produced, which will be explained
in detail below.
[0031] The forming mandrel may, for example, have a smooth,
convexly curved tool tip. It may be symmetrical or asymmetrical.
The tool tip may also be formed by a rotatably disposed ball which
rolls on the series-produced skin part during the working of the
series-produced skin part, whereby the mechanical stressing of the
series-produced skin part is reduced in the forming area. As an
alternative, a "rolling mandrel" may also be used, in the case of
which the tool tip is formed by a wheel or by a roller. Multiple
mandrels or multiple-armed mandrels may also be used. However, the
forming mandrel must not necessarily have a round or rounded tip.
On the contrary, a forming mandrel with a relatively sharp-edged
tip may also be used. As an alternative, the tip may also end
flatly, be wheel-shaped, plow-shaped or similar to a hull shape. A
forming mandrel with a facetted tool tip is also contemplated.
[0032] The forming mandrel also does not necessarily have to
consist of steel or tool steel. Forming mandrels made of a plastic
material, of wood, ice, sand, concrete or other materials are also
contemplated. The tool tip of the forming mandrel may be hardened,
unhardened, coated or uncoated. It may, for example, be provided
with a wear-resistant single or hybrid coating. In this case, the
forming mandrel may be guided in up to six axes relative to the
component in order to achieve the desired "forming result". During
the reworking, the forming mandrel or the tool tip of the forming
mandrel may be rotated or oscillated also about the longitudinal
axis of the forming mandrel.
[0033] A forming mandrel with or without lubrication may be used. A
lubricating system may, for example, be integrated in the forming
mandrel. The lubricating system may also be arranged on the outside
on the forming mandrel. The lubricating system ensures that the
"working point", that is, the point at which the forming mandrel
touches the series-produced skin part, is continuously supplied
with sufficient lubricant. A lubricating oil can be used as the
lubricating fluid.
[0034] In addition, a forming mandrel may be used whose tool tip
can be adjusted during the working operation. It may, for example,
be provided that the width of the tool tip can be changed
transversely to the moving direction of the tool mandrel during the
working operation. In this manner, geometries of a variable
"broadness" may be produced in a single operation.
[0035] The moving speed at which the forming mandrel is moved
during the reworking relative to the series-produced vehicle body
skin part does not have to be constant. On the contrary, the moving
speed may be varied as a function of the momentary "degree of
deformation" of the series-produced skin part. At lower degrees of
deformation, a high moving speed can be selected; at higher degrees
of deformation, a lower moving speed can be selected.
[0036] During the working, the forming mandrel as well as the
"workpiece" may be heated or cooled or have an ambient temperature,
if required. In the case of series-produced vehicle body skin parts
made of sheet metal, but mainly in the case of "workpieces" made of
a plastic material, it may be advantageous to heat the forming
mandrel or the tool tip of the forming mandrel during the working
of the series-produced skin part. A heating of the forming mandrel
results in a feeding of heat into the area of the workpiece to be
formed, whereby its ductility is increased, which facilitates the
forming. Particularly in the case of plastic parts, this
facilitates the forming.
[0037] As an alternative or in addition thereto, the
series-produced skin part may also be preheated or heated directly
during the reworking. The series-produced skin part may be heated
by hot air, heat radiators, lasers or by another heat source.
Series-produced vehicle body skin parts may be preheated during the
reworking to barely below a material-specific "softening
temperature" and/or may be heated by means of a heated forming
mandrel or a point-type additional heating at the intervention
point locally to a suitable "forming temperature".
[0038] Before the reworking, the workpiece may also be pretreated
by other methods. It can, for example, be irradiated, coated,
etched, hardened, roughened, smoothed, polished, sprayed with a
lubricating liquid or ground. It can also be pretreated by
sand-blasting before the reworking.
[0039] The reworking of the series-produced vehicle skin body part
preferably takes place in a fully automatically controlled manner.
The forming mandrel may either be constructed as a working tool of
a CNC machine tool, similar to U.S. Pat. No. 6,216,608 B1, or may
be arranged on an arm of a correspondingly programmed working
robot. Naturally, such a "working station" may also have additional
"tools", such as a laser cutting device, by means of which the body
skin part may additionally be trimmed.
[0040] Other objects, advantages and novel features of the present
invention will become apparent from the following detailed
description of the invention when considered in conjunction with
the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] FIG. 1 is a view of a vehicle body skin part having a form
elevation, which was produced by a reworking according to the
invention;
[0042] FIGS. 2, 3 are sectional views of the vehicle body skin part
of FIG. 1;
[0043] FIG. 4 is a view of the basic principle of the reworking of
a series-produced vehicle body skin part according to the
invention;
[0044] FIG. 5 is a view of the basic principle of the reworking
according to the invention when using a die-type counterholder;
[0045] FIGS. 6 to 8 are various cross-sectional views of a form
elevation impressed additionally into a prefabricated
component;
[0046] FIGS. 9 to 11 are views of embodiments in which the
component to be reworked is supported by counterholders;
[0047] FIG. 12 is a schematic representation of a possible movement
of the forming tool;
[0048] FIG. 13 is a view of an embodiment in which a front opening
hood is reworked; and
[0049] FIG. 14 is a view of a die-type counterholder.
DETAILED DESCRIPTION OF THE DRAWINGS
[0050] FIG. 1 illustrates a series-produced vehicle body skin part
1. The series-produced body skin part 1 of FIG. 1 is an "outer door
skin". A form elevation 2 was "additionally" formed into the
series-produced vehicle skin sheet metal part 1, which will be
explained in detail in connection with the following figures.
[0051] FIG. 2 is a sectional view of the skin part 1 of FIG. 1
along the intersection line A-A. The form elevation 2 has a length
l and a depth t. The depth t of the form elevation 2 has its
maximum in the area of the z-axis of FIG. 2 and decreases toward
the ends of the form elevation 2.
[0052] FIG. 3 is a cross-sectional view of the vehicle body skin
part 1 along the intersection line B-B of FIG. 1. It is shown that
the form elevation 2 is relatively sharp-edged. Very accentuated
characteristic lines of this type are difficult to produce or
cannot be produced at all by use of conventional deep-drawing
methods.
[0053] FIG. 4 schematically describes the reworking operation of
the series-produced vehicle body skin part 1. The series-produced
body skin part 1 is clamped into a holding device 3 (not shown in
detail) or is fixed on a holding device 3. In the embodiment
illustrated here, the series-produced vehicle body skin part 1 is
fixed on the holding device 3 only in its edge areas. Subsequently,
a forming mandrel 4 is guided onto the series-produced skin part 1
and is pressed with a defined contact pressure force against the
series-produced body skin part 1. In a next step, the forming
mandrel 4 is moved relative to the series-produced vehicle body
skin part 1 in the direction of the arrow 5. Simultaneously, an
"application movement" of the forming mandrel 4 relative to the
series-produced vehicle body skin part 1 takes place, whereby the
form elevation 2 is impressed into the series-produced body skin
part 1 by way of the tip 6 of the forming mandrel 4.
[0054] FIG. 5 shows an embodiment in which a counterpressure is
applied by means of a die-type counterholder 7 from the side of the
series-produced vehicle body skin part 1 situated opposite the
forming mandrel 4. Thus, the series-produced body skin part 1 is
supported by the die-type counterholder 7, which permits the
production of a sharp-edged contour, as illustrated in FIG. 5,
without any problem. The die-type counterholder may be a
component-specific tool or a "universal tool", which may also be
used for the individualization of other series-produced body skin
components.
[0055] FIGS. 6 to 8 are different cross-sectional views A-A, B-B
and C-C, respectively, of a form elevation 2 additionally impressed
into a series-produced skin part 1.
[0056] FIG. 6b is a cross-sectional view along the intersection
line A-A. FIGS. 6a, 6b illustrate an embodiment in which a very
accentuated form elevation 2 was additionally impressed in the
series-produced skin part 1, the "tip" of the form elevation 2
being slightly rounded.
[0057] FIG. 7b is the cross-sectional view B-B. In this area, the
form elevation 2 is less accentuated. In comparison to FIG. 6b, the
"tip" of the form elevation 2 has a greater radius of
curvature.
[0058] FIG. 8b is the cross-sectional view C-C. In this area, the
form elevation 2 is again more accentuated. Similarly to FIG. 6b,
the "tip" of the form elevation 2 has a relatively small radius of
curvature.
[0059] FIG. 9 illustrates an embodiment in which, during the
reworking, the series-produced skin part 1 is supported by two
essentially equally wide counterholders 8, 9 from the side situated
opposite the forming mandrel 4. Reference number 1' indicates the
contour of the series-produced skin part before the reworking.
Here, the "tip" of the forming mandrel 4 is more accentuated than
in the case of the forming mandrel 4 illustrated in FIG. 10. The
counterholder 8 is arranged at a distance L1 from the "center" of
the form elevation to be produced or from the tip of the forming
mandrel 4; the counterholder 9 is arranged at a distance L2. The
counterholders 8, 9 therefore have a spacing L3 which is equal to
the sum of the spacings L1 and L2. Here, L1 is smaller than L2. The
supporting therefore takes place asymmetrically with respect to the
position of the tip of the forming mandrel 4. By changing the
spacings L1, L2 and L3 respectively, the supporting or clamping-in
condition of the series-produced skin part 1, and therefore, also
the form of the form elevation to be produced may be changed.
[0060] FIG. 10 shows an embodiment in which the counterholder 8 is
wider than the counterholder 9. Here, the supporting with respect
to the tip of the forming mandrel 4 takes place only slightly
asymmetrically. The reason is that L1 is only slightly larger than
L2. In comparison to FIG. 9, the tip of the forming mandrel 4 is
more blunt here, which results in a correspondingly less
accentuated form elevation.
[0061] FIG. 11 shows an embodiment in which the counterholders 8, 9
are arranged at a relatively small mutual distance L3. This permits
relatively large degrees of deformation and, as illustrated in the
drawing, the production of a relatively strongly accentuated form
elevation.
[0062] FIG. 12 shows the moving path of the forming mandrel on the
example of a series-produced vehicle skin part 1, such as an engine
hood, into which two characteristic lines 2a, 2b are impressed.
From a point 10 in space, which is here called the "starting point"
of the forming tool, the forming tool (not shown) is first lowered
onto the series-produced body skin part 1. Pressed against the
series-produced body skin part 1 while a suitable contact pressure
force is applied, the forming tool is then moved along the
characteristic line 2a to be produced. After the production of the
characteristic line 2a, the forming tool is lifted and reaches the
point 11 in space. From there, the forming tool is moved to point
12 in space. Subsequently, it is again lowered to the
series-produced body skin part 1 and is moved along the
characteristic line 2b to be produced. After the production of the
characteristic line 2b, the forming tool is lifted and reaches
point 13 in space.
[0063] FIG. 13 shows the "engine hood" 1 of FIG. 12 after the
production of the characteristic lines 2a and 2b. In addition,
according to the same method, a center elevation 2c was impressed
into the engine hood metal sheet, which elevation 2c protrudes
upward out of the engine hood, similar to the illustration in FIGS.
6 to 8.
[0064] FIG. 14 shows a die 14 which can be used for producing a
form elevation, such as the form elevation 2c of FIG. 13. The die
14 is pressed against the series-produced body skin part (not shown
here), specifically from the side situated opposite the forming
tool 4. The die 14 is provided for the partial supporting of the
forces exercised by the forming tool 4 upon the series-produced
body skin part. Similar to FIG. 14, the die 14 may be U-shaped;
that is, open on one side. As an alternative, it may also be closed
which is comparable to a plate with an oblong hole. However, the
invention is not limited to a certain die form but covers all die
forms.
[0065] As illustrated in FIG. 14, the inner edge of the die 14 is
flattened diagonally toward the interior in the "inlet area" of the
forming tool 4. In contrast, in the lateral areas 16 of the die 14,
the inner edge is essentially perpendicular to the supporting
surfaces 17, 18 of the die 14, which supporting surfaces 17, 18
press "from the rear" against the series-produced body skin part
during the reworking operation and in the process support the
forces exercised by the forming tool. For the purpose of
completeness, the moving path 19 of the forming tool should also be
mentioned, which extends essentially in the center with respect to
the two legs of the die 14.
[0066] The foregoing disclosure has been set forth merely to
illustrate the invention and is not intended to be limiting. Since
modifications of the disclosed embodiments incorporating the spirit
and substance of the invention may occur to persons skilled in the
art, the invention should be construed to include everything within
the scope of the appended claims and equivalents thereof.
* * * * *