U.S. patent application number 11/668645 was filed with the patent office on 2007-05-31 for method and apparatus for marking workpieces.
Invention is credited to Albrecht Schneider.
Application Number | 20070122224 11/668645 |
Document ID | / |
Family ID | 27214103 |
Filed Date | 2007-05-31 |
United States Patent
Application |
20070122224 |
Kind Code |
A1 |
Schneider; Albrecht |
May 31, 2007 |
METHOD AND APPARATUS FOR MARKING WORKPIECES
Abstract
A method and an apparatus are provided for marking a
sheet-shaped workpiece using a marking tool. The marking tool is
mounted in a punch holder of a punch press and a counter-support is
fixed in place on a side opposite of a marking surface of the
workpiece to be marked. The surface of the workpiece is marked by
displacing the workpiece in its plane while engaging the marking
tool with the workpiece. In one form, a support roller provides
counter-support. In another form, an elastic element is
cooperatively associated with the punch stroke of the punch press
to translate an exactly defined contact pressure force between the
tool tip and the workpiece to be marked.
Inventors: |
Schneider; Albrecht;
(Oberursel, DE) |
Correspondence
Address: |
STITES & HARBISON PLLC
1199 NORTH FAIRFAX STREET
SUITE 900
ALEXANDRIA
VA
22314
US
|
Family ID: |
27214103 |
Appl. No.: |
11/668645 |
Filed: |
January 30, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10747216 |
Dec 30, 2003 |
7168364 |
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11668645 |
Jan 30, 2007 |
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09881678 |
Jun 18, 2001 |
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10747216 |
Dec 30, 2003 |
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09688094 |
Oct 16, 2000 |
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09881678 |
Jun 18, 2001 |
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Current U.S.
Class: |
400/134 |
Current CPC
Class: |
Y10T 29/5116 20150115;
B41J 3/385 20130101; Y10T 83/0348 20150401; Y10T 83/0333 20150401;
B21C 51/005 20130101; Y10T 83/0304 20150401; B21D 17/02 20130101;
B44B 5/0019 20130101; Y10T 83/023 20150401; Y10T 83/02
20150401 |
Class at
Publication: |
400/134 |
International
Class: |
B41J 3/38 20060101
B41J003/38 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 14, 1999 |
DE |
199 49 552.1 |
Oct 7, 2000 |
DE |
100 49 701.2 |
Claims
1. An device for marking a sheet-shaped workpiece, comprising: a
tool holder having a support and adapted to be mounted in a punch
press and constructed to receive at its upper end a force of a
punch press to move the support downwardly, a marking tool mounted
in the support and having a sheet marking tip at its lower end, and
an elastic element operatively mounted in the device between the
support and the marking tool, the support being movable downwardly
by a force received from a punching press, until the marking tip
engages the workpiece, after which further downward movement of the
support compresses the elastic element to cause the marking tip to
increase its force against the workpiece.
2. The device of claim 1, including a pressure plate located in the
support and positioned to receive the force of the elastic element
and transfer such force to the marking tool.
3. The device of claim 2, including a guide insert mounted at the
lower end of the guide support and a tool shaft extending from the
pressure plate, through the guide insert to the marking tip.
4. The device of claim 1, including a driving head positioned to
receive a force of a punching press and transfer such force to the
support.
5. The device of claim 4, including a guide bushing positioned to
transfer a force of a punching press from the driving head to the
support.
6. The device of claim 1, including a counter-support located on
the opposite side of the workpiece from the marking tip.
7. The device of claim 1, wherein the counter-support includes at
least one rotatable support roller or support ball.
8. The device of claim 1, in combination with a punching press in
which the device is disposed.
9. The device of claim 1, wherein the elastic element is a metallic
spring.
10. The device of claim 1, wherein the elastic element is a
pneumatic spring.
11. The device of claim 1, wherein the elastic element is a
hydraulic spring.
12. The device of claim 1, wherein the marking tip is selected from
the group consisting of diamond, boron nitride, or a hard
alloy.
13. The device of claim 1, wherein the support is adjustable to
vary the position of the marking tip and/or the pre-stress of the
elastic element.
14. The device of claim 1, wherein the marking tool comprises an
ink point for writing a marking on the surface of the workpiece.
Description
FIELD OF THE INVENTION
[0001] This application is a continuation of application Ser. No.
10/747,216 filed Dec. 30, 2003, which is a continuation of
application Ser. No. 09/881,678 filed Jun. 18, 2001, which is a
continuation-in-part of prior application Ser. No. 09/688,094 filed
Oct. 16, 2000.
[0002] The present invention relates to a method and an apparatus
for marking workpieces on a punching press, wherein the marking
tool is forced by means of the punching stroke either against the
surface of the workpiece or a certain depth into the surface of the
workpiece. The workpiece, which is generally a piece of flat sheet
metal, is displaced within its plane in order to create a straight
or curved marking line.
BACKGROUND OF THE INVENTION
[0003] There is an increasing demand for altering the surface of
workpieces, including as one example, providing workpieces with
individual identifications. In this connection the use of stamping
dies is not always practical because the stamping is often also
visible on the back of sheet metal workpiece. Difficulties in
connection with stamping dies occur particularly when it is
intended to punch parts of different lengths out of a sheet metal
workpiece (e.g., in order to minimize waste) and wherein a certain
orientation of the marking on the workpiece is desirable.
[0004] A known method for marking sheet metal consists of embossing
dot matrices to produce an alpha-numeric symbol with the aid of a
pointed embossing tool. The workpiece must be moved stepwise after
each dot has been embossed. This results in a multitude of required
stamping stroke cycles, just to represent a single symbol. Besides
the large amount of required time and the increased wear of the
driving mechanism for the stroke, which is driven in a quasi
load-free manner, the loud noise is considered to be a
disadvantage. A coarser dot matrix does simplify the marking
process, but it also results in a more unsatisfactory matrix.
[0005] A qualitatively appealing marking can be achieved by
inscribing markings into the surface of the workpiece, wherein no
waviness or "rear embossing" will occur. Borries Markiersystem GmbH
of Pliezhausen, for example, offers a machine, by means of which
inscribing the desired identification is possible by displacing a
tip forced into the surface of the workpiece in accordance with the
contours of the marking.
[0006] It would seem that in principle one could employ such a
known marking device in a punch press. However, if this were done,
the space available for the main punching operation would be
reduced and the progress of the main punching operation would be
made more difficult. Also, this marking device could only operate
within a limited portion of the area of the punch press so that
movement of the sheet metal workpiece in order to apply markings on
different areas thereof would become more difficult.
SUMMARY OF THE INVENTION
[0007] It is an object of the present invention to create an
improved apparatus for altering the surface of a sheet metal
workpiece, which apparatus can be integrated into a punching
process in a punch press.
[0008] This object is attained in accordance with the invention by
a method and an apparatus wherein a tool is equipped with a tip
which, after having been forced against or into the surface of the
workpiece, is maintained at a fixed position, at which time the
workpiece is displaced in its plane in accordance with the desired
result, and thereafter the tip is moved away from the workpiece to
its rest position.
[0009] The principles of the present invention can be utilized to
mark workpieces in many different ways. For example, a tool can be
forced to a certain depth into the surface of the workpiece for an
inscribing action. Or, a tool can be forced against the surface,
without going beneath the surface, for the purpose of marking the
surface. In another application, if the workpiece has a protective
plastic cover over a metal base, such as a sheet metal base, a tool
can be utilized to cut the plastic cover, while not altering the
underlying metal sheet. These various applications of the present
invention will be referred to as marking the workpiece, and the
different apparatus and tools will be referred to as marking tools,
or marking apparatus.
[0010] The production of markings of any arbitrary symbol or shape
on or in the workpiece surface is made possible by means of the
marking tool being placed on the punch press without any
additional, space-consuming devices. At the same time a marking
method is optimally integrated into the punching process so that,
for example with a turret punch press, a sheet metal workpiece is
first marked at the desired locations and thereafter is finished by
means of the tools seated in other holders of the punch press. The
marking tool may be arranged in a punch tool holder so that the
marking can be made from above the workpiece. The orientation of
the marking can be determined by means of the software which
controls the workpiece driving mechanism.
[0011] It is also advantageous in connection with the operation of
the invention that the tool tip need be moved only once into its
marking position, so that the number of punch strokes which must be
performed by the punch press is considerably reduced. The results
are reduced noise generation and reduced wear of the stroke driving
mechanism.
[0012] In one preferred embodiment of the invention, at least a
portion of the punch stroke is absorbed by an elastic element which
extends between a table for seating the workpiece and the punch
tool holder.
[0013] Since punch presses are designed for very high processing
forces, with high precision and almost load-free, it can be very
difficult under certain circumstances to move the stroke driving
mechanism into a precisely defined position. To compensate for
this, it is possible by an elastic element to achieve considerably
more precise movement of the tool tip on or into the surface of the
workpiece. In the process, the elastic element translates the
relatively large punch stroke of the punch press into an exactly
defined contact pressure force of the tool tip, which leads to the
desired marking position.
[0014] In a further preferred embodiment of the invention at least
one marking is formed as a center mark, wherein, following pressing
the tool tip, the workpiece is maintained in its predefined
position until the marking tool is retracted.
[0015] It is desirable for some applications to be able to set a
center mark on the workpiece, for example in order to be able to
position or center bolts or pins which are to be welded onto the
workpiece. The provision of the center mark can be integrated into
the marking process and apparatus in accordance with the invention,
wherein it might be advantageous if, in connection with a center
mark, the tool tip were pressed deeper into the workpiece than the
usual inscribing depth.
[0016] For example, when making a center mark it is possible in a
further development of the invention that by different positioning
of the tool tip with respect to a counter-support, for example, the
spring travel of the tool tip reaches its maximum before it has
reached the deepest depth in the workpiece. While making surface
marks or inscribing are performed by means of a resilient tool tip,
the latter rests against a stop when making a center mark.
[0017] It has been shown to be practical to guide the workpiece by
means of at least one support roller which may be elastically
spring-loaded in the area of the workpiece support table since,
among other things, the support roller provides the required
support for the workpiece while not hampering the displacement of
the workpiece.
[0018] In one preferred embodiment, the present invention comprises
at least one marking tool disposed in a punch press where the
marking tool includes a tool tip, a guide bush axially supporting a
support, and a marking tool elastic element operatively connecting
a drive head to the tool tip. At least one counter-support is
located opposite the marking tool and fixed in place on a side
opposite of a marking surface of a workpiece to be marked. When the
apparatus has a workpiece disposed between the marking tool and the
counter-support, the marking tool is operable to be pressed onto or
into a marking surface of the workpiece against a restoring force
of the marking tool elastic element and mark the workpiece when the
workpiece is translated in its plane.
[0019] In another form of the present invention, an apparatus for
marking a sheet shaped workpiece comprises at least one marking
tool fixed in place in a punch holder of a punch press and at least
one counter-support fixed in place on the side of the workpiece
located opposite the marking tool such that a workpiece can be
disposed between the marking tool and a counter-support. The
marking tool has a tool tip which can be pressed into or onto the
workpiece against a restoring force of an elastic element. The
elastic element is cooperatively associated with a punch stroke of
the punch press to provide an exactly defined contact pressure
force between the tool tip and a workpiece to be marked.
[0020] The counter-support preferably comprises at least one
rotatable roller. The counter-support roller along with workpiece
support table rollers facilitate movement of the workpiece during
marking. Moreover the counter-support roller provides mobility
without damage to the workpiece surface, and minimizes frictional
losses such that they occur only at the contact point between the
workpiece and counter-support roller.
[0021] For an inscribing marking tool, a tool with a cone shaped
tip is used. The tip is preferably forced into the workpiece
surface, so that an inscribing force is achieved regardless of the
direction of movement. Shapes which are not round are also
conceivable. Moreover, the inscribing element may cut grooves of
different thicknesses into the workpiece surface.
[0022] In accordance with yet another preferred embodiment, the
marking tool has an adjustable support, by means of which the
position of the tool tip and/or the prestress of its elastic
element can be adjusted.
[0023] The adjustable support makes possible the individual
adaptation of the contact depth, for example in order to improve
the clarity of the shapes formed in the workpiece, or to make
possible an adaptation to the material of the workpiece.
[0024] As mentioned above, with the present invention, it is
possible to make a marking such as an ink marking or the like on
the surface of the sheet metal instead of inscribing the marking
into the sheet metal. Making an ink marking would use the same
method and apparatus as described above with respect to inscribing
except that the method and the equipment would be adjusted such
that the marking tools such as a pen or the like would simply be
forced with sufficient pressure against the surface of the
workpiece, as opposed to entering into the surface of the
workpiece. Any suitable pen could be used including for example, a
ball-point pen, a roller ball pen, a felt tip pen or a grease
pencil.
[0025] Alternatively, a marking tool made of brass, plastic or any
other material which is incapable of cutting the workpiece may be
utilized for the purpose of marking a shape in a protective
covering placed over the workpiece without damaging the
workpiece.
[0026] Thus, it is an object of the present invention to provide a
new and improved method and apparatus for marking a workpiece,
wherein the apparatus is incorporated within a punch press.
[0027] It is another object of the present invention to provide a
new and improved method and apparatus for marking a sheet-shaped
workpiece in conjunction with a punch press, wherein the marking
can be either inscribed into the surface of the workpiece, made as
an ink marking on the surface of the workpiece or made as a cut in
a protective covering placed over the workpiece.
[0028] It is a further object of the present invention to provide a
new and improved method and apparatus for marking a sheet-shaped
workpiece in conjunction with a punch press where an elastic
element is associated with the punch stroke of the punch press to
translate an exactly defined contact pressure force between a
marking tool tip and a workpiece to be marked.
[0029] These and other objects of the present invention will become
more apparent from the detailed description to follow.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The invention will now be described in detail with respect
to preferred embodiments of the invention wherein:
[0031] FIG. 1 is a central cross sectional view of a marking tool
for insertion into a punch holder of a punching press; and
[0032] FIG. 2 is an enlarged view of a portion of FIG. 1, but
showing a modification thereof.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0033] Referring now to the drawings, like elements are represented
by like numerals throughout the several views.
[0034] Referring to FIG. 1, the marking tool has a guide bush 14,
in which a support 16 is axially guided, and a driving head 20,
which are in engagement with each other via a threaded connection
22. By means of a guide insert 24, the support 16 holds a marking
tool 26, Which is axially movable with respect to the support 16
and has a tool shaft 28 which is guided in an appropriately fitted
bore 30 of the guide insert 24, a pressure plate 32, formed at the
top of the shaft 28, as well as an inscribing element 34, seated on
the free lower end of the shaft 28. The tip 34 of the marking tool
can be of different constructions, depending on the type of mark to
be made. In a first embodiment, the tip 34 may be made of a hard
material and shaped as a pointed cone to be used as an inscribing
element. As an inscribing element, 34 can be made, for example, of
a diamond, boron nitride, a hard metal, or an otherwise suitable
material for inscribing the respective workpiece.
[0035] The axial mobility of the marking tool 26 in relation to the
support 16 is limited by a first shoulder 36 of a bore 38 in the
support 16, and by the top 40 of the guide insert 24 inserted into
the bore 38. A compression spring 44, arranged under prestress
between a second shoulder 42 and the pressure plate 32, urges the
pressure plate 32 downwardly against the top 40 of the guide insert
24.
[0036] In the exemplary embodiment represented, the workpiece 12 is
a sheet metal plate which rests on a counter-support 46 with a
rotatably seated ball 48, wherein the contact point between the
workpiece 12 and the ball 48 lies exactly in alignment with the
inscribing element 34.
[0037] In a preferred form, the workpiece 12 is guided by means of
support rollers, such as support rollers 50 mounted in workpiece
support table 54. Rollers 50 are elastically spring-loaded by
compression springs 52.
[0038] To inscribe a symbol on the workpiece 12, the workpiece is
first appropriately aligned with the marking tool 10. Thereafter,
lowering of the marking tool 26 is started by actuating the stroke
driving mechanism of the punch press, which acts on the driving
head 20, wherein the guide bush 14 is urged against the support 16
by means of a shoulder 49. In the course of the downward movement
of the support 16 the marking tool 26 is initially moved along
until the element 34 rests on the surface to be cut. The continued
downward movement of the support 16 leads to compression of the
compression spring 44, and therefore the pressure exerted on the
pressure plate 32 steadily increases. Where the element 34 is a
diamond tip, it will actually penetrate the surface of the
workpiece as a result of the pressure exerted by the compression
spring. Maximum penetration depth is reached at the end of the
punch stroke. The compression spring 44 provides for precise
movement of the tool tip 34 on or into the surface of workpiece 12.
During marking, the compression spring 44 translates a relatively
large punch stroke of the punch press into an exactly defined
contact pressure force of the tool tip 34 which leads to a desired
marking position.
[0039] In some applications, it is desirable to use an element 34
which is not capable of penetrating the surface of the workpiece
12. Here, instead of utilizing a diamond tip, the element 34 is
constructed from a material which does not penetrate the workpiece.
It is often desirable to protect the workpiece 12 from inadvertent
scratches or other blemishes which can occur during processing. For
example, if the workpiece is stainless steel and will ultimately be
used in the manufacture of an appliance or the like, the workpiece
12 may be covered with a plastic film or other protective covering
during the hole punching or cutting operations. In order to create
holes in the workpiece 12 in such cases, it is desirable to remove
areas of the protective covering where the workpiece 12 will
eventually be cut by a punch or a laser. This is necessary because
the protective covering may interfere with the accuracy of such
cuts in the workpiece 12. In order to cut holes in the protective
covering without damaging the workpiece 12, a marking element 34
constructed from plastic or brass, or another material which is too
soft to penetrate the workpiece may be utilized. Thus, when
pressure is exerted by the compression spring 44, the element 34
will penetrate the surface of the protective covering (not shown),
but will not penetrate the surface of the workpiece 12.
[0040] An adjustment of the penetration depth of the element 34
(when used as an inscribing element) can be performed by a relative
turning of the driving head 20 in relation to the support 16. This
changes the effective total combined length of support 16 and
driving head 20. With this increased length of the support 16 and
driving head 20 the element 34 reaches the surface to be cut
earlier in the punch stroke and the pressure built up by means of
the compression spring 44 becomes correspondingly greater.
[0041] As an inscribing marking tool, as soon as the element 34
reaches its inscribing position, the stroke driving mechanism of
the punch press is blocked. Conversely, if the stroke driving
mechanism of the punch press did not permit the marking tool to
stop in the inscribing position, a separate detent device must be
provided between the support 16 and the guide bush 14. With the
element 34 held down, the workpiece 12 is now displaced in its
plane in order to form the contours of the symbol or shape to be
inscribed, wherein any arbitrary orientation of the symbol or shape
is possible by an appropriate control of the workpiece driving
mechanism. When the symbol or shape has been completely inscribed,
the stroke driving mechanism is reversed, wherein first the support
16 is moved away from the workpiece 12 because of the diminishing
pressure force by the compression spring 44 and, following the
contact of the pressure plate 32 with the top 40 of the guide
insert 24, the element 34 is lifted off the workpiece 12. The
workpiece 12 is appropriately horizontally displaced within its
plane and the inscribing process is repeated for inscribing
additional symbols or shapes.
[0042] During the horizontal displacement of the workpiece 12, the
roller ball 48 of the counter-support 46 follows this movement,
wherein an optimal counter-support directly in alignment with the
inscribing element 34 always exists. Because the roller ball 48
turns, sliding movements against the underside of the workpiece 12
are prevented, so that the underside of the workpiece 12 is not
detrimentally affected.
[0043] Where the marking tool of FIG. 1 is used in a punch press
the guide bush 14 is adapted to the tool holder and the driving
head 20 is adapted to the stroke driving mechanism of the punch
press.
[0044] The compression spring 44 can be replaced with a
pneumatically or hydraulically operating pressure spring.
[0045] FIG. 2 illustrates a modification of the present invention
wherein, instead of an inscribing element, there is provided an ink
point 134 for marking the surface of the workpiece 12 without
penetrating same. Ink point 134 is shown at the lower end of a
shaft 134 mounted in guide insert 24 of FIG. 1. All of the above
described features of all embodiments of the invention can utilize
an ink point 134 to mark the surface of a workpiece in place of the
previously described elements for inscribing the workpiece and/or
forming a center mark. As would be understood by one of ordinary
skill in the art, when using an ink marking point 134, one would
simply adjust movements of all of the other movable parts such that
instead of penetrating the workpiece, the apparatus would move the
ink point 134 to a position where it exerted sufficient force onto
the workpiece to form an ink marking. As with the other
embodiments, the workpiece 12 could then be displaced horizontally
within its plane so as to form an ink shape or symbol of straight
or curved lines. Any type of known ink point could be used such as
a ball-point, a roller ball point, a felt tip or a grease
pencil.
[0046] Although the invention has been described in considerable
detail with respect to preferred embodiments thereof, it will be
apparent that the invention is capable of numerous modifications
and variations, apparent to those skilled in the art, without
departing from the spirit and scope of the invention.
* * * * *