U.S. patent application number 16/595125 was filed with the patent office on 2020-01-30 for eddy current separation of blanks for the automated destacking of aluminum sheet.
This patent application is currently assigned to Ford Motor Company. The applicant listed for this patent is Ford Motor Company. Invention is credited to Seth Avery, Ralph Conrad, Randal Dively, Andrey Ilinich, Franco Leonardi, S. George Luckey, JR., Patrick McCleer.
Application Number | 20200030869 16/595125 |
Document ID | / |
Family ID | 68694986 |
Filed Date | 2020-01-30 |
United States Patent
Application |
20200030869 |
Kind Code |
A1 |
Dively; Randal ; et
al. |
January 30, 2020 |
EDDY CURRENT SEPARATION OF BLANKS FOR THE AUTOMATED DESTACKING OF
ALUMINUM SHEET
Abstract
A method of separating blanks from a stack includes positioning
a magnetic field generator in a fixed location proximate a
peripheral edge of an upper portion of the stack, activating the
magnetic field generator such that eddy currents are generated and
result in a force vector in a direction away from a top-most blank
of the stack, and pushing a blank, or multiple blanks, immediately
below the top-most blank away from the top-most blank by the eddy
currents.
Inventors: |
Dively; Randal; (Monroe,
MI) ; Conrad; Ralph; (South Lyon, MI) ;
Luckey, JR.; S. George; (Dearborn, MI) ; Ilinich;
Andrey; (Novi, MI) ; Leonardi; Franco;
(Dearborn Heights, MI) ; Avery; Seth; (Livonia,
MI) ; McCleer; Patrick; (Jackson, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ford Motor Company |
Dearborn |
MI |
US |
|
|
Assignee: |
Ford Motor Company
Dearborn
MI
|
Family ID: |
68694986 |
Appl. No.: |
16/595125 |
Filed: |
October 7, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15993460 |
May 30, 2018 |
|
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16595125 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B21D 43/24 20130101 |
International
Class: |
B21D 43/24 20060101
B21D043/24 |
Claims
1. A method of separating a blank from a stack of blanks
comprising: positioning a magnetic field generator in a fixed
location proximate a peripheral edge of an upper portion of the
stack; activating the magnetic field generator such that eddy
currents are generated and result in a force vector in a direction
away from a top-most blank; and pushing, by the magnetic field
generator, at least one blank immediately below the top-most blank
away from the top-most blank after the top-most blank is lifted by
an external device, wherein the magnetic field generator is
disposed relative to the stack in a way such that the force vector
is applied on the at least one blank to separate the at least one
blank from the top-most blank before the top-most blank and the at
least one blank are completely separated from remaining blanks of
the stack.
2. The method according to claim 1, wherein the blanks are an
aluminum alloy material.
3. The method according to claim 1, wherein the magnetic field
generator is an electromagnet.
4. The method according to claim 1, wherein the magnetic field
generator is a rotating assembly of permanent magnets having
alternating north and south poles.
5. The method according to claim 1 further comprising injecting air
into a side of the stack as the individual blanks are separated by
the eddy currents.
6. The method according to claim 1, wherein a width of the blanks
is between about 25 mm to about 3000 mm, a length of the blanks is
between about 25 mm to about 3000 mm, a thickness of each blank is
between about 0.5 mm to about 6.0 mm, and a height of the stack of
blanks is between about 1 mm to about 2000 mm.
7. The method according to claim 1 further comprising a step of
moving the top-most blank to a subsequent manufacturing
operation.
8. The method according to claim 1, wherein only one sheet at a
time is displaced by the magnetic field generator.
9. The method according to claim 1, wherein the gravitational
direction is between 90 degrees and 75 degrees as measured from a
normal face of a blank.
10. An apparatus for separating blanks from a stack comprising: a
fixed magnetic field generator; a jig configured to hold and
translate the stack of blanks past the fixed magnetic generator
such that a peripheral edge of an upper portion of the stack is
continually positioned proximate the fixed magnetic field
generator; and a position sensor for detecting a position of the
jig, wherein eddy currents from the fixed magnetic field generator
force an unwanted blank immediately below a top-most blank of the
stack to be separated from the top-most blank of the stack and to
fall with gravity after the top-most blank is lifted by an external
device, and wherein the fixed magnetic field generator is disposed
relative to the stack in a way such that the eddy currents separate
the unwanted blank from the top-most blank before the top-most
blank and the unwanted blank are completely separated from
remaining blanks of the stack.
11. The apparatus according to claim 10, wherein the magnetic field
generator includes a polyphase winding.
12. The apparatus according to claim 10, wherein the magnetic field
generator is a rotating assembly of permanent magnets having
alternating north and south poles.
13. The apparatus according to claim 10 further comprising an air
knife configured to inject air into the stack as the unwanted blank
is separated by the eddy currents.
14. The apparatus according to claim 10 further comprising a
transport mechanism configured to move the top-most blank to a
subsequent manufacturing operation.
15. The apparatus according to claim 14, wherein the transport
mechanism comprises a plurality of suction cups configured to hold
the top-most blank of the stack.
16. The apparatus according to claim 14, wherein the transport
mechanism comprises a robot with an end effector to hold the stack
of blanks.
17. The apparatus according to claim 10 further comprising a
controller configured to transmit signals to the jig for
translational movement.
18. The apparatus according to claim 17, wherein the position
sensor is in communication with the controller to transmit the
position of the jig to the controller.
19. The apparatus according to claim 10, wherein the stack of
blanks is not injected with any current by way of physical
contact.
20. The apparatus according to claim 10 wherein the eddy currents
result in a force vector in a direction between 90 degrees and 75
degrees as measured from a normal face of a blank.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of and claims the benefit
of U.S. application Ser. No. 15/993,460, filed May 30, 2018, and
titled "Eddy Current Separation of Blanks for the Automated
Destacking of Aluminum Sheet," the content of which is incorporated
herein by reference in its entirety.
FIELD
[0002] The present disclosure relates to a material handling
machine and method, and more particularly to an apparatus and a
method for separating blanks.
BACKGROUND
[0003] The statements in this section merely provide background
information related to the present disclosure and may not
constitute prior art.
[0004] In a material forming operation, such as a stamping
operation, a stack of blanks is generally positioned in proximity
to a stamping press and automatically fed into a stamping press by
a material handling machine, such as a material handling robot.
Tool and die surfaces of the stamping press receive the blanks and
form the blanks into a desired shape. The robot includes an
end-effector, which is moved to a position above the stack of
blanks, grasps and lifts the uppermost blank from the stack, and
feeds the uppermost blank into the stamping press.
[0005] To facilitate the grasping operation of the end-effector,
the stack of blanks may be de-stacked or separated before the
end-effector grasps the uppermost blank. The typical de-stacking
method is not suitable for high-volume manufacturing cycle time
which requires automated, rapid, and robust blank de-stacking. If
two or more blanks are picked up by the robot, the system
experiences a disruption and stops the production line, resulting
in downtime of the manufacturing process.
[0006] Moreover, the typical de-stacking method is not suitable for
picking up a variety of blank materials and of varying dimensions.
For example, a typical de-stacking method that works with steel
blanks may not work with aluminum blanks.
[0007] These issues associated with de-stacking equipment relative
to material blanks, and the limitation of only certain materials
being handled, are addressed by the present disclosure.
SUMMARY
[0008] In one form, a method of separating a blank from a stack of
blanks is provided, which includes positioning a magnetic field
generator in a fixed location proximate a peripheral edge of an
upper portion of the stack, activating the magnetic field generator
such that eddy currents are generated and result in a force vector
in a direction away from a top-most blank, and pushing a blank, or
multiple blanks, immediately below the top-most blank away from the
top-most blank by the eddy currents.
[0009] In other features, the blanks are an aluminum alloy
material, and the magnetic field generator is an electromagnet. The
magnetic field generator is a rotating assembly of permanent
magnets having alternating north and south poles. The method
further includes injecting air into a side of the stack as the
individual blanks are separated by the eddy currents, and moving
the top-most blank to a subsequent manufacturing operation. Only
one sheet at a time is displaced by the magnetic field generator. A
width of the blanks is between about 25 mm to about 3000 mm, a
length of the blanks is between about 25 mm to about 3000 mm, a
thickness of each blank is between about 0.5 mm to about 6.0 mm,
and a height of the stack of blanks is between about 1 mm to about
2000 mm. The gravitational direction is between 90 degrees and 75
degrees as measured from a normal face of a blank.
[0010] According to other features, the magnetic field generator
includes a polyphase winding. The magnetic field generator is a
rotating assembly of permanent magnets having alternating north and
south poles. The apparatus may further include an air knife
configured to inject air into the stack as the blank is separated
by the eddy currents, a transport mechanism configured to move the
top-most blank to a subsequent manufacturing operation, a
controller configured to transmit signals to the jig for
translational movement, and a position sensor in communication with
the controller to transmit a position of the jig to the controller.
In one form, the transport mechanism includes a plurality of
suction cups configured to hold the top-most blank of the stack,
and a robot with an end effector to hold the stack of blanks.
Advantageously, the stack of blanks is not injected with any
current by way of physical contact. In one form, the eddy currents
result in a force vector in a direction between 90 degrees and 75
degrees as measured from a normal face of a blank.
[0011] Further areas of applicability will become apparent from the
description provided herein. It should be understood that the
description and specific examples are intended for purposes of
illustration only and are not intended to limit the scope of the
present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The present disclosure will become more fully understood
from the detailed description and the accompanying drawings,
wherein:
[0013] FIG. 1 is a schematic view of an apparatus for separating a
blank from a stack of blanks constructed in accordance with the
teachings of the present disclosure;
[0014] FIG. 2 is a schematic view of one form of a magnetic field
generator operable with the apparatus of FIG. 1 according to the
teachings of the present disclosure;
[0015] FIG. 3 is a schematic view of a stack of blanks and one
variation of a magnetic field generator operable with the apparatus
of FIG. 1 according to the teachings of the present disclosure;
[0016] FIG. 4 is a schematic view of a stack of blanks and another
variation of a magnetic field generator operable with the apparatus
of FIG. 1 according to the teachings of the present disclosure;
and
[0017] FIG. 5 is a flow diagram of a method for separating blanks
from a stack in accordance with the teachings of the present
disclosure.
[0018] Corresponding reference numerals indicate corresponding
parts throughout the several views of the drawings.
DETAILED DESCRIPTION
[0019] The following description is merely exemplary in nature and
is not intended to limit the present disclosure, application, or
uses.
[0020] Referring to FIG. 1, a material handling apparatus 10 for
separating a blank from a stack of blanks and for moving the
separated blank to a desired location in accordance with the
teachings of the present disclosure is shown. The material handling
apparatus 10 in one form is used as part of a stamping press (not
shown) in a manufacturing operation using conductive blanks, such
as aluminum and steel alloys. Generally, the material handling
apparatus 10 includes a transport mechanism, such as a robot 12, a
fixed magnetic field generator 16, an optional air knife 18, and a
jig 20 for holding and supporting the stack of blanks 22.
[0021] The robot 12 may include a robot arm 13 and an end-effector
14 attached to the robot arm 13. The end-effector 14 may include a
plurality of suction cups supplied with a vacuum via a hose 15 such
that the end-effector 14 applies a suction force and thereby
securely grasps and moves a separated blank from the stack of
blanks 22. Alternatively, the end-effector 14 may include a
multi-fingered gripper or any conventional means that can grasp and
move the separated blank. The separated blank is moved by the
end-effector 14 and fed into a stamping press (not shown), with the
robot arm 13 moving back and forth between the stamping press and
the stack of blanks 22 until all of the blanks in the stack have
been sequentially fed into the press. (Only portions of the robot
12 are shown via a schematic inset 11 for illustrative
simplicity).
[0022] As described in greater detail below, the magnetic field
generator 16 is used to remove unwanted blank(s) stuck to a
top-most blank 23 when the top-most blank 23 is grasped by an
end-effector 14 so that the top-most blank 23 can be separated from
the remaining blanks in the stack of blanks 22 to avoid inadvertent
separation of more than one blank by the end-effector 14. More
specifically, the end-effector 14, with its suction force, may
grasp more than one blank from the stack of blanks 22 at a time.
The magnetic field generator 16 generates a repulsive force F to
push any unwanted blank(s) that are stuck to the top-most blank 23
downward. The unwanted blanks that are stuck to the top-most blank
23 can be further separated with the assistance of gravitational
force G, rather than separating individual blanks as with
conventional blank separating equipment. Further, the individual
blanks are not physically touched by any equipment/components of
the material handling apparatus 10.
[0023] Referring to FIG. 2, the magnetic field generator 16 in one
form is a solenoid 17, which employs a polyphase winding to
generate a moving (translating) magnetic field M and eddy currents
19, which produce the force vector F that functions to separate an
unwanted blank that is stuck to the top-most blank 23, from the
top-most blank 23. In one form, the polyphase winding may be a
three phase winding. The magnetic field generator 16 is fixed and
is configured such that the force generated by the eddy currents 19
pushes any unwanted blank that is stuck to the top-most blank 23
downward as shown in FIG. 1, the separation of which is further
assisted by the gravitational force G. The direction of the
magnetic force produced by the eddy currents 19 of the magnetic
field generator 16 is determined by a charge and vector product of
the charge velocity and the magnetic field according to Equation
1:
F.sub.B=qv.times.B (Equation 1) where: [0024] F.sub.B=magnetic
force vector [0025] q=charge [0026] V=velocity vector of the charge
[0027] B=magnetic field vector
[0028] Accordingly, the magnetic field generator 16 is configured
such that the direction of the force of the eddy currents 19 to
separate an unwanted blank from the top-most blank 23 is downward,
in a gravitational direction G, as shown. The force F may be in the
range of 5 lbs to 200 lbs depending on the application, and may
vary further from these exemplary values.
[0029] The material handling apparatus 10 may optionally include a
controller 24 for actuating the jig 20 to move the stack of blanks
22 up and down along a Z-direction. The controller 24 is configured
to move the jig 20 and position the stack of blanks 22 to a
predetermined height relative to the stationary magnetic field
generator 16 for an optimum separation force between the unwanted
blank that is disposed immediately below the top-most blank 23 from
the top-most blank 23. The jig 20 moves the stack of blanks 22 from
an elevated position and progressively upwardly along the
Z-direction such that a peripheral edge of an upper portion of the
stack is continually positioned proximate the fixed magnetic field
generator 16. A position sensor 30 may be disposed at the jig 20
and in communication with the controller 24 to transmit a signal
corresponding to a position of the jig 20 to the controller 24.
[0030] Optionally, the air knife 18 is configured to inject air
into the stack of blanks 22 as the top-most blank 23 is sucked by
the end-effector 14 and the blank immediately below the top-most
blank 23 is separated from the top-most blank 23 by a repulsive
force F resulting from the local eddy currents of the magnetic
field generator 16. The robot 12 is configured to move the top-most
blank 23, which has been separated from the stack of blanks 22, to
a target site for a subsequent manufacturing operations.
[0031] Referring to FIG. 3, another form of a magnetic field
generator 16' is shown that is disposed adjacent to the stack of
blanks 22 and includes a rotor 25 and a plurality of magnets 26,
which are permanent magnets, to form a rotating assembly.
Similarly, the magnetic field generator 16' does not contact the
stack of the blanks 22. The plurality of magnets 26 are arranged to
extend in radial directions of the rotor 25 and are spaced apart in
the circumferential direction of the rotor 25, with north (N) and
south (S) poles alternately arranged.
[0032] Rotation of the magnets 26 with alternating polarities
results in a constantly changing magnetic field, which induces an
eddy current in a nearby conductor, i.e., within the edge of the
blanks 22. A magnetic force is equal to the product of an electric
current, a magnetic field, and a length of a given conductor, in
this instance the blank immediately below the top-most blank 23.
The interaction between the magnetic field generated by the magnet
field generator 16 and the eddy current in the blanks 22 generates
an opposing repulsive force F between the blanks 22 and the
rotating magnets 22 that serves to move the edge of the blank
immediately below the top-most blank 23 away from the top-most
blank 23. The blank immediately below the top-most blank 23 then
falls due to gravity. The repulsive force F is in a direction
defining an angle .theta. relative to the front face of the blank
22, which is between 75.degree. and 90.degree. in one form of the
present disclosure. The opposing repulsive force F produces a
targeted "blank fanning" effect in which the generated magnetic
force is produced in a controlled and targeted manner to separate
the blanks 22.
[0033] The magnitude of the opposing repulsive force F depends on
the rotational speed of the rotor 25, the magnetic field strength
of the magnets 26, and the diameter of the rotor 25. Therefore, the
repulsive force F resulting from the eddy currents and the magnetic
field may be carefully tuned according to the specifications of the
blanks 22 (e.g., size, thickness, material).
[0034] Referring to FIG. 4, another variant of the magnetic
generator 16'' constructed in accordance with the teaching of the
present disclosure includes an inclined surface 42 facing edges of
the stack of blanks 22, and an array of electromagnets 44 mounted
along the inclined surface 42 and disposed in close proximity to
the edge of the blanks 22. Similarly, the magnetic field generator
16'' does not contact the edges of the stack of blanks 22. The
array of electromagnets 44 are computer-controlled and are operable
to induce eddy currents within the edges of the blanks 22 by
changing the magnetic field generated by the array of
electromagnets 44. The computer (not shown) controls the array of
the electromagnets 44 such that the electromagnetic field moves in
reference to the edge of the blanks 22, thereby generating an
opposing repulsive force F between the blanks 22 and the array of
electromagnets 44. The electromagnetic field moves at an angle
.theta. between 90 and 75 degrees relative to the front face of the
blanks 22. The opposing repulsive force F in the blank edge serves
to push down the blank that is disposed immediately below the
top-most blank. Again, the unwanted blank immediately below the
top-most blank 23 is pushed down, in a gravitational direction.
This feature is one among several that distinguishes the teachings
of the present disclosure from those of the prior art. Further, the
material handing apparatus 10 and various forms of magnetic field
generators 16/16'/16'' advantageously do not inject any current by
way of physical contact into the stack of blanks 22, which results
in a simpler and more efficient operation to separate and move
blanks throughout various manufacturing operations such as
stamping.
[0035] Referring now to FIG. 5, a method 50 of separating a blank
from a stack of blanks 22 and moving a separated blank to a target
site starts with positioning a magnetic field generator 16 in a
fixed location proximate a peripheral edge of an upper portion of
the stack in step 52. A top-most blank is lifted by, for example,
an end-effector in step 54. The magnetic field generator is
activated such that eddy currents and a magnetic force vector
(i.e., a repulsive force) in a gravitational direction away from
the top-most blank 23 are generated in step 56. In one form, the
gravitational direction is between 90 degrees and 75 degrees as
measured from a front face of a blank, and as illustrated in FIGS.
2 and 3. Therefore, an unwanted blank that is stuck to the top-most
blank 23 is moved away from the top-most blank 23 in the
gravitational direction in step 58. Concurrently and optionally,
air may be injected into the stack as individual blanks are
separated by the repulsive force resulting from the eddy currents.
Finally, the top-most blank 23 that is separated from the stack is
moved to a subsequent manufacturing operation, which may be by the
robot 12 shown in FIG. 1 in step 60.
[0036] The blanks 22 may be any conductive materials where eddy
currents can be induced, such as aluminum alloys and steel alloys.
In one form of high-volume automotive production, a width of the
blanks is between about 25 mm to about 3000 mm, a length of the
blanks is between about 25 mm to about 300 mm, a thickness of each
blank is between about 0.5 mm to about 6.0 mm, and a height of the
stack of blanks is between about 6 mm to about 2000 mm.
[0037] The apparatus and the method of the present disclosure are
intended to eliminate the need for compressed air, dimple patterns,
or other typical methods to facilitate separation of the blanks in
stamping or other operations.
[0038] The description of the disclosure is merely exemplary in
nature and, thus, variations that do not depart from the substance
of the disclosure are intended to be within the scope of the
disclosure. Such variations are not to be regarded as a departure
from the spirit and scope of the disclosure.
* * * * *