Electric heating – Metal heating – By arc
Reexamination Certificate
2001-09-05
2003-08-19
Elve, M. Alexandra (Department: 1725)
Electric heating
Metal heating
By arc
C219S121830
Reexamination Certificate
active
06608282
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to machine tools, more particularly relates to apparatus for automatically loading machine tools, and in particular to an apparatus for automatically loading machine tools which operate on sheet or plate including a CNC punch press machine tool, a CNC punch press machine tool having a thermal cutting apparatus such as a plasma torch or a laser, a plasma cutting machine tool or a laser cutting machine tool.
BACKGROUND OF THE INVENTION
FIGS. 1 and 2
are provided for background, and show a well-known type of punch press with thermal cutting capability, associated with a loader mechanism. The punch press is representative of the broad range of machine tools with which a loader according to the present invention can be associated. In greater detail,
FIG. 1
shows machine tool
1
, a CNC punch press having a loading apparatus
2
. CNC punch press
1
has an X-axis
3
based on a rail
3
′ supported by bracket
4
and pedestals
5
and
5
′, carrying a translatable table
6
.
Translatable table
6
is driven by a servomotor and ballscrew that cannot be seen and carries two workclamps
7
and
7
′ for gripping the work, and several sets of punching tools
8
. The Y-axis is defined by a frame
9
carrying a translatable punching cylinder
10
and a translatable die support
11
. Punching cylinder
10
is driven via a servomotor
200
connected by coupling
201
to ballscrew
202
. At the left side and connected to the mounting plate of punching cylinder
10
is a plasma torch
203
for cutting large holes and the outer boundary of parts from workpiece
17
. Below and to the immediate left of torch
203
is a drop leaf table apparatus
204
for removal of small parts after they have been cut from material
17
. An electrical cabinet houses the CNC
12
along with other electrical controls, and operator station
13
provides the man/machine interface for machine tool
1
. Worktable
14
on the right side of frame
9
and worktable
15
on the left side of frame
9
and drop leaf table
204
are adapted with ball transfers
16
to support the material
17
to be processed. Material
17
is flat, rectangular metal sheet and plate.
In operation, material
17
is gripped by workclamps
7
and
7
′ and moved and positioned under CNC control along X axis
3
while punching cylinder
10
and die support
11
are moved and positioned under CNC control along the Y-axis. The work is positioned and tools are selected according to a part program processed by the CNC
12
. At commanded positions the CNC
12
cycles punching cylinder
10
to punch a hole in the work. After all holes have been punched the CNC
12
in like manner positions the plasma torch
203
to commanded positions, lowers plasma torch
203
to the work
17
, ignites plasma torch
203
then coordinates the velocity and motion of the X and Y axes to move plasma torch
203
along a described path to create a hole or to cut a part from material
17
. Small parts cut from the material are unloaded via drop leaf table
204
and large parts are removed manually, with the assist of a hoist or crane, or by other means.
A supply of material
17
is staged on loading apparatus
2
at the right side of machine tool
1
. Loading apparatus
2
typically includes a base
77
′ having a freestanding column
18
supporting a power driven cantilevered beam
19
, pivotable at the proximal end of cantilevered beam
19
about supporting point
20
. Cantilevered beam
19
is often further strengthened by a support rod
21
, connected to cantilevered beam
19
at
22
and pivotally connected to column
18
directly above and inline with supporting point
20
. Carried at the distal end of cantilevered beam
19
is a pivotable member
23
, which is pivotable about bearing
24
. In the illustrated embodiment two bearings
24
are mounted to plates
24
′ bolted to the distal end of beam
19
, one attached to the upper side of beam
19
and one to the bottom side of beam
19
. The angular position of pivotable member
23
relative to machine tool
1
is fixed by a four bar linkage to stabilize the pivotable member
23
so as to maintain the long side of rectangular material
17
generally parallel to the X axis
3
of machine tool
1
.
The first bar of the four bar linkage is attachment plate
25
, which is connected to freestanding column
18
. The second bar is bar
26
pivotally connected to attachment plate
25
and pivotally connected to pivotable member
23
. The third bar is bar
27
pivotally connected to attachment plate
25
and pivotally connected to pivotable member
23
. The fourth bar is the pivotable member or extension
23
.
In the present embodiment, part handling apparatus generally indicated at
29
a
include mast
28
which is carried by and connected to pivotable member
23
, and is adapted to support and vertically translate load beam
29
via cylinder
30
. Bars
31
are adjustably connected to load beam
29
and are adapted with vacuum cups
31
′ to pick up material
17
.
The powered drive for the cantilevered beam
19
is shown as a cylinder
32
, which is pivotally connected at
33
to a plate
34
attached to freestanding column
18
, and pivotally connected to cantilevered beam
19
at
35
. Curved line
36
traces the path of the center of the mast as cantilevered beam
19
is pivoted by cylinder
32
. Line
37
generally traces the path of the front edge of material
17
as it is transferred from the staging position to worktable
14
and workclamps
7
and
7
′ of machine tool
When commanded to load a sheet of material, cylinder
30
lowers the vacuum cups to the supply of material
17
. A sensor detects the presence of a sheet for pickup. The vacuum cups are engaged to grip the top sheet, cylinder
30
lifts the load beam picking up the top sheet of material, cylinder
32
pivots cantilevered beam
19
clockwise until the sheet is over worktable
14
, cylinder
30
lowers the load beam and attached sheet to the surface of worktable
14
, cylinder
32
pivots cantilevered beam clockwise to urge the sheet into the workclamps and toward workclamp registration surfaces
39
′ and
39
. Sensors associated with workclamp registration surfaces detect the sheet is loaded and cause the workclamps to grip the sheet. Then the vacuum cups release the sheet, cylinder
30
lifts the load beam and vacuum cups above the sheet, and cylinder
32
pivots cantilevered beam
19
counterclockwise positioning it once more over material
17
at the staging area.
While loader apparatus
2
can reliably deliver sheets of material to worktable
14
of machine tool
1
, it cannot reliably load the material into workclamps
7
and
7
′ in a registered orientation. If the sheet
17
in the supply stack is perfectly aligned with the X-axis of the machine tool, the four bar linkage is designed to deliver the sheets to the workclamps in parallel alignment with the X-axis as desired. But very often the sheet in the supply stack is not perfectly aligned, and therefore delivery into the workclamps is not reliably accomplished.
FIG. 2
is an enlarged drawing of the material loading side of machine tool
1
showing a fragment of machine tool
1
. Like objects are identified with the same numbers as in FIG.
1
. Workpiece
17
,
FIG. 2
, is shown residing in an angular relationship to the X-axis of machine tool
1
. Such conditions can occur several ways. The sheet may have been improperly stacked in preparation, the stack of material may have been jostled during transport, or the stack may have been improperly loaded on the loader staging station.
Workpiece
17
′,
FIG. 2
, represents workpiece
17
after it is loaded on worktable
14
. Note that the left end of sheet
17
′ is in contact with registration surface
39
′ while the right end is not in contact with registration surface
39
. Loader
2
is a typical machine tool quality device with typical machine tool accuracy and repeatability, and it therefore lacks adequate co
Julian Alfred J.
Schaaf Sidney B.
Tomlinson Michael A.
Elve M. Alexandra
Leydig , Voit & Mayer, Ltd.
W.A. Whitney Co.
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