U.S. patent number RE31,042 [Application Number 06/199,631] was granted by the patent office on 1982-09-28 for laser cutting head attachment for punch presses.
This patent grant is currently assigned to Houdaille Industries, Inc.. Invention is credited to Victor T. Carbone, Stephen C. Clark.
United States Patent |
RE31,042 |
Clark , et al. |
September 28, 1982 |
Laser cutting head attachment for punch presses
Abstract
A turret punch machine tool equipped with controlled automatic
x-y axis workpiece movement mechanisms for moving the workpiece
over a stationary work table section adjacent a punching station is
provided with a separate laser beam generator and with a tool frame
carried vertically retractable and extendable laser cutting head in
optical communication with the beam generator. The beam generator
is capable of producing both laser pulses of varying duration and
spacing or a continuous beam. The cutting head is provided with two
gas inputs one for use with the continuous beam, a second for use
with the pulse beam, and controls are provided to automatically
provide varying combinations of use of the punch and laser.
Inventors: |
Clark; Stephen C. (East
Amherst, NY), Carbone; Victor T. (Cheektowaga, NY) |
Assignee: |
Houdaille Industries, Inc. (Ft.
Lauderdale, FL)
|
Family
ID: |
26894976 |
Appl.
No.: |
06/199,631 |
Filed: |
October 22, 1980 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
937754 |
Aug 29, 1978 |
04201905 |
May 6, 1980 |
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Current U.S.
Class: |
219/121.67;
219/121.6; 219/121.78; 219/121.82; 219/121.84; 219/68 |
Current CPC
Class: |
B21D
28/12 (20130101); B23K 26/0093 (20130101); B23K
26/123 (20130101); B23K 26/1436 (20151001); B23K
26/1476 (20130101); B23K 26/064 (20151001); B23K
26/142 (20151001); B23K 26/1435 (20130101) |
Current International
Class: |
B21D
28/02 (20060101); B21D 28/12 (20060101); B23K
26/14 (20060101); B23K 26/08 (20060101); B23K
026/00 () |
Field of
Search: |
;219/68,121L,121LM,121LG,121LN,121LU,121LY,121FS,121LK
;83/410,552 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Panelmaster CNC Model 848, Catalog 848-77, W. A. Whitney, pp. 1-8,
copyright 1977. .
IEEE Journal of Quantum Electronics, vol. QE-10, No. 2, pp.
179-185, Feb. 1974, "Metal Processing With a High-Power CO.sub.2
Laser", by E. Locke, R. Hella. .
Optics and Laser Technology, vol. 5, No. 6, Dec. 1973, pp. 256-265,
"Printing of Part Numbers Using a High Power Laser Beam", by G.
Holzinger, K. Kosanke, W. Menz. .
Jemma Mechanika a Optika, vol. 20, No. 11, pp. 329-333, Nov. 1975,
"A Laser Drilling Machine", by Vavrouch et al. .
The Fabricator, Sep./Oct. 1976, pp. 1, 20, 22, 23, 30, "Lasers:
Applications for Metal Processing", by Neil Forbes. .
American Machinist, Jul. 1, 1975, pp. 41-56, "Lasers in
Metalworking", by George Schaffer. .
Manufacturing Engineering & Management, Dec. 1974, pp. 26-28,
"Advent of the Job-Shop Laser", Edited by Bernard Feinberg. .
Optical Spectra, Apr. 1975, "The Laser is a Processor", by Rivie
Levin. .
"Photon Sources: Innovators for Manufacturing Through Laser
Technology", Sales Brochure Published by Photon Sources, Inc.,
Livonia, Michigan, Jan. 1978. .
Messr Griesheim GmbH, Feb. 1974, "The Lasers Future in Metalwork",
by Manfred Hoffman, Reprint from IPC Science & Technology Press
Ltd., Guilford Surrey, Jan. 1974. .
Messr. Griesheim GmbH, Jun. 1975, "Economic Cutting With CO.sub.2
-Lasers", Reprint From Schweissen und Schneide, vol. 3/75, Pub. by
DVS-Verlag Dusseldorf. .
"Strippit," Sales Brochure published by Strippit, Houdaille, Akron,
N.Y., 1972..
|
Primary Examiner: Reynolds; B. A.
Assistant Examiner: Paschall; M.
Attorney, Agent or Firm: Hill, Van Santen, Steadman, Chiara
& Simpson
Claims
We claim as our invention:
1. In a machine tool punch press having a main frame, main frame
carried upper and lower spaced rotatable turrets respectively
carrying punch tools and die tools, a main frame carried vertically
reciprocatable punch ram stationed at a work station, a worktable
extending outwardly from adjacent the lower turret at least to the
sides and front thereof having at least a stationary portion
adjacent the lower turret, the stationary portion aligned with the
work station and spaced to a side thereof, a central automatic
control controlling the turrets and punch ram and further
controlling workpiece movement apparatus effective to move a
workpiece with respect to at least the stationary portion of the
worktable and the work station, the improvement of:
(a) a vertically movable laser cutting head carried by the main
frame above the stationary portion of the worktable, the cutting
head including a hollow tip assembly adjacent the bottom thereof
and a beam focusing optical means adjustably fixably spaced from a
bottom of the tip assembly and vertically movable with the cutting
head,
(b) a laser beam generator, the laser beam generator being spaced
from the machine tool punch press and main frame and being
substantially isolated therefrom whereby vibration of the machine
tool punch press is isolated from the beam generator,
(c) an optical beam pathway interconnecting the cutting head and
the laser beam generator, the pathway including beam bending optics
directing a laser beam through the tip, an opening through the
stationary portion of the worktable aligned with the laser beam
eminating from the hollow tip,
(d) a control means automatically alternatively controlling
punching operation and laser operation from said central automatic
control, said control means including means for vertically moving
the cutting head in dependent relationship to selection of laser
operation, said control means being a portion of said central
control.
2. A device according to claim 1 including at least one gas supply
system actuatable to deliver gas under pressure to the interior of
the hollow tip, said gas supply system including a supply of
exothermic reaction producing gas, said control means including
means for activating the gas system in dependent relation to
selection of laser operation.
3. A device according to claim 2 including at least two gas supply
systems independently actuatable to deliver gas under pressure to
the tip interior, a first of the systems supplying an exothermic
reaction producing gas and a second of the systems supplying a gas
of a lesser exothermic reaction capability than the gas of the
first of the systems, the laser beam generator having selectable,
continuous and pulsed operation modes, the control means including
means for selecting one of said modes and means for selecting
actuation of one or another of said gas supply systems.
4. A device according to claim 3 wherein the control means includes
means for lowering said cutting head to an operating position from
an elevated storage position in dependent response to selection of
laser operation.
5. In a machine tool punch press having a main frame, main frame
carried upper and lower spaced rotatable turrets respectively
carrying punch tools and die tools, a main frame carried vertically
reciprocatable punch ram stationed at a work station, a worktable
extending outwardly from adjacent the lower turret at least to the
sides and front thereof having at least a stationary portion
adjacent the lower turret, the stationary portion aligned with the
work station and spaced to a side thereof, a central automatic
control controlling the turrets and punch ram and further
controlling workpiece movement apparatus effective to move a
workpiece with respect to at least the stationary portion of the
worktable and the work station, the improvement of:
(a) a vertically movable laser cutting head carried by the main
frame above the stationary portion of the worktable, the cutting
head including a hollow tip assembly adjacent a bottom thereof and
a beam focusing optical means vertically movable with the cutting
head,
(b) at least two gas supply systems independently actuatable to
deliver gas under pressure to the tip interior, a first of the
systems supplying an exothermic reaction producing gas,
(c) a laser beam generator, the laser beam generator being spaced
from the machine tool punch press and main frame and being
substantially isolated therefrom whereby vibration of the machine
tool punch press is isolated from the beam generator,
(d) an optical beam pathway interconnecting the cutting head and
laser beam generator,
(e) control means automatically alternatively controlling punching
operation and laser operation from said central automatic control,
said control means including means for activating a selected one of
the gas systems.
6. In a machine tool punch press having a main frame, main frame
carried upper and lower spaced rotatable turrets respectively
carrying punch tools and die tools, a main frame carried vertically
reciproctable punch ram stationed at a work station, a worktable
extending outwardly from adjacent the lower turret at least to the
sides and front thereof having at least a stationary portion
adjacent the lower turret, the stationary portion aligned with the
work station and spaced to a side thereof, a central automatic
control controlling the turrets and punch ram and further
controlling workpiece movement apparatus effective to move a
workpiece with respect to at least the stationary portion of the
worktable and the work station, the improvement of:
(a) a vertically movable laser cutting head carried by the main
frame above the stationary portion of the worktable, the cutting
head including a hollow tip assembly adjacent a bottom thereof and
a beam focusing optical means vertically movable with the cutting
head,
(b) at least two gas supply systems independently actuatable to
deliver gas under pressure to the tip interior, first of the
systems supplying an exothermic reaction producing gas,
(c) a laser beam generator, the laser beam generator being spaced
from the machine tool punch press and main frame and being
substantially isolated therefrom whereby vibration of the machine
tool punch press is isolated from the beam generator,
(d) an optical beam pathway interconnecting the cutting head and
laser beam generator,
(e) control means automatically alternatively controlling punching
operation and laser operation from said central automatic control,
said control means including means for activating a selected one of
the gas systems in dependent relationship to selection of the one
of the operating modes of the laser. .Iadd. 7. In a machine tool
punch press having a frame, frame carried upper and lower spaced
rotatable turrets respectively carrying punch tools and die tools,
a frame carried vertically reciprocatable punch ram stationed at a
work station, a worktable extending outwardly from adjacent the
lower turret at least to the sides and front thereof having at
least a stationary portion adjacent the lower turret, the
stationary portion aligned with the work station and spaced to a
side thereof, a central automatic control controlling the turrets
and punch ram and further controlling workpiece movement apparatus
effective to move a workpiece with respect to at least the
stationary portion of the worktable at the work station, the
improvement of:
(a) a vertically movable laser cutting head carried in fixed
relation to said frame above the stationary portion of the
worktable, the cutting head including a hollow tip assembly
adjacent the bottom thereof and a beam focusing optical means
adjustably fixably spaced from a bottom of the tip assembly and
vertically movable with the cutting head,
(b) a laser beam generator, the laser beam generator being spaced
from the machine tool punch press and frame and being substantially
isolated therefrom whereby vibration of the machine tool punch
press is isolated from the beam generator,
(c) an optical beam pathway interconnecting the cutting head and
the laser beam generator, the pathway including beam bending optics
directing a laser beam through the tip, an opening through the
stationary portion of the worktable aligned with the laser beam
emanating from the hollow tip,
(d) a control means automatically alternatively controlling
punching operation and laser operation from said central automatic
control, said control means including means for vertically moving
the cutting head in dependent relationship to selection of laser
operation, said control means
being a portion of said central control. .Iaddend..Iadd. 8. In a
machine tool punch press having a main frame, main frame carried
upper and lower spaced tool holders respectively carrying punch
tools and die tools, a main frame carried vertically reciprocatable
punch ram stationed at a work station, a worktable extending
outwardly from adjacent the lower tool holder at least to the sides
and front thereof having at least a stationary portion adjacent the
lower tool holder, the stationary portion aligned with the work
station and spaced to a side thereof, a central automatic control
controlling the tool holders and punch ram and further controlling
workpiece movement apparatus effective to move a workpiece with
respect to at least the stationary portion of the worktable and the
work station, the improvement of:
(a) a vertically movable laser cutting head carried by the main
frame above the stationary portion of the worktable, the cutting
head including a hollow tip assembly adjacent the bottom thereof
and a beam focusing optical means adjustably fixably spaced from a
bottom of the tip assembly and vertically movable with the cutting
head,
(b) a laser beam generator, the laser beam generator being spaced
from the machine tool punch press and main frame and being
substantially isolated therefrom whereby vibration of the machine
tool punch press is isolated from the beam generator,
(c) an optical beam pathway interconnecting the cutting head and
the laser beam generator, the pathway including beam bending optics
directing a laser beam through the tip, an opening through the
stationary portion of the worktable aligned with the laser beam
emanating from the hollow tip,
(d) a control means automatically alternatively controlling
punching operation and laser operation from said central automatic
control, said control means including means for vertically moving
the cutting head in dependent relationship to selection of laser
operation, said control means
being a portion of said central control. .Iaddend..Iadd. 9. In a
machine tool punch press having a frame means, said frame means
carrying upper and lower spaced tool holders respectively carrying
punch tools and die tools, said frame means carrying a vertically
reciprocatable punch ram stationed at a work station, a worktable
extending outwardly from adjacent the lower tool holder at least to
the sides and front thereof having at least a stationary portion
adjacent the lower tool holder, the stationary portion aligned with
the work station and spaced to a side thereof, a central automatic
control controlling the tool holders and punch ram and further
controlling workpiece movement apparatus effective to move a
workpiece with respect to at least the stationary portion of
worktable and the work station, the improvement of:
(a) a vertically movable laser cutting head carried in fixed
relationship to said frame means above the stationary portion of
the worktable, the cutting head including a hollow tip assembly
adjacent the bottom thereof and a beam focusing optical means
adjustably fixably spaced from a bottom of the tip assembly and
vertically movable with the cutting head,
(b) a laser beam generator, the laser beam generator being spaced
from the machine tool punch press and frame means and being
substantially isolated therefrom whereby vibration of the machine
tool punch press is isolated from the beam generator,
(c) an optical beam pathway interconnecting the cutting head and
the laser beam generator, the pathway including beam bending optics
directing a laser beam through the tip, an opening through the
stationary portion of the worktable aligned with the laser beam
emanating from the hollow tip,
(d) a control means automatically alternatively controlling
punching operation and laser operation from said central automatic
control, said control means including means for vertically moving
the cutting head in dependent relationship to selection of laser
operation, said control means
being a portion of said central control. .Iaddend..Iadd. 10. In a
machine tool punch press having a frame means, said frame means
carrying upper and lower spaced tool holding means respectively
carrying punch tools and die tools, said frame means carrying a
vertically reciprocatable punch ram stationed at a work station, a
worktable extending outwardly from adjacent the lower tool holding
means at least to the sides and front thereof having at least a
stationary portion adjacent the lower tool holding means, the
stationary portion aligned with the work station and spaced to a
side thereof, a central automatic control controlling the tool
holding means and punch ram and further controlling workpiece
movement apparatus effective to move a workpiece with respect to at
least the stationary portion of the worktable and the work station,
the improvement of:
(a) a vertically movable laser cutting head carried in fixed
relationship to said frame means above the stationary portion of
the worktable, the cutting head including a hollow tip assembly
adjacent a bottom thereof and a beam focusing optical means
vertically movable with the cutting head,
(b) at least two gas supply systems independently actuatable to
deliver gas under pressure to the tip interior, a first of the
systems supplying an exothermic reaction producing gas,
(c) a laser beam generator, the laser beam generator being spaced
from the machine tool punch press and main frame and being
substantially isolated therefrom whereby vibration of the machine
tool punch press is isolated from the beam generator,
(d) an optical beam pathway interconnecting the cutting head and
laser beam generator,
(e) control means automatically alternatively controlling punching
operation and laser operation from said central automatic control,
said control means including means for activating a selected one of
the gas
systems. .Iaddend..Iadd. 11. In a machine tool punch press having a
main frame, main frame carried upper and lower spaced tool holders
respectively carrying punch tools and die tools, a main frame
carried vertically reciprocable punch ram stationed at a work
station, a worktable extending outwardly from adjacent the lower
tool holder at least to the sides and front thereof having at least
a stationary portion adjacent the lower tool holder, the stationary
portion aligned with the work station and spaced to a side thereof,
a central automatic control controlling workpiece movement
apparatus effective to move a workpiece with respect to at least
the stationary portion of the worktable and the work station, the
improvement of:
(a) a vertically movable laser cutting head carried by the main
frame above the stationary portion of the worktable, the cutting
head including a hollow tip assembly adjacent a bottom thereof and
a beam focusing optical means vertically movable with the cutting
head,
(b) at least two gas supply systems independently actuatable to
deliver gas under pressure to the tip interior, first of the
systems supplying an exothermic reaction producing gas,
(c) a laser beam generator, the laser beam generator being spaced
from the machine tool punch press and main frame and being
substantially isolated therefrom whereby vibration of the machine
tool punch press is isolated from the beam generator,
(d) an optical beam pathway interconnecting the cutting head and
laser beam generator,
(e) control means automatically alternatively controlling punching
operation and laser operation from said central automatic control,
said control means including means for activating a selected one of
the gas systems in dependent relationship to selection of the one
of the operating modes of the laser. .Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to machine tools and more particularly to a
turret punch press equipped with a laser cutting and marking
assembly.
2. Prior Art
Automatic computer controlled turret punch machine tools are known
to the art wherein the machine tool is provided with computer
controlled work piece movement gripping devices which move the
workpiece accurately in both x and y axis directions with respect
to a punching station. Movement of the workpiece is generally done,
at least in part, over a stationry work table portion surrounding
the lower turret of the machine tool. Controls and mechanisms for
such workpiece movement have become so sophisticated that workpiece
movement speeds in excess of 1500 inches per minute on either axis
are known. Additionally, punch ram movements on the order of 400
strokes a minute are also known. Thus, modern computer controlled
turret punches represent highly versatile machine tools capable of
quickly and accurately providing sheet metal and plastics with
desired punched out areas. However, the versatility of such turret
punches is limited in that material can be removed from the
workpiece only by a punching type operation. Thus, when large areas
of the workpiece are to be removed, or when the workpiece is to be
subdivided into a number of separable workpieces, or when
relatively long or large diameter cuts are to be made, this can be
accomplished only by a series of slightly overlapping punching type
metal removal operations. This is generally referred to as
"nibbling". Although such overlapping material removal operations
can effectively be used to increase the versatility of a punch,
those operations have, at times, undesired consequences, such as
formation of burred edges, inability to produce highly accurate,
smooth arcuate side edges, relative slowness of operation, etc. As
a result, many cutting or shearing type operations are performed by
other machine tools in a subsequent operation which requires
additional workpiece handling.
In order to increase the ability of automatic punching equipment to
provide large and/or irregularly shaped holes in the workpiece, it
has been suggested to equip the punch press with a plasma arc
cutting torch. See for example U.S. Pat. No. 4,063,059. Such
cutting torches are frequently undesirable in that they have
inherent disadvantages such as relatively large kirfs, ragged edges
and large heat distort areas adjacent the cut.
Although it has been known to provide metal cutting machines
utilizing techniques other than plasma arc torches, including laser
beam cutting machines, such devices have not previously been
integrated with machine tool turret punches.
Among other reasons for the art to have not attempted a combination
of a laser cutting device and a machine tool turret punch is the
fact that during punching operations, the entire machine tool is
subjected to pounding vibrations. Since lasers are highly sensitive
devices, it has hitherto been thought that they would not be
adaptable for use in high shock and vibration locations.
It would, therefore, be an advance in the art to combine a laser
cutting tool with a machine tool computer controlled turret
punch.
Moreover, it is often times desirable to surface mark a workpiece
at a precisely predetermined position. Punching machines are
primarily designed for material removal and are not generally
capable of surface marking. The same is true with respect to
cutting lasers.
It would, therefore, be a further advance in the art to provide a
combination turret punch and laser cutting assembly having
capabilities of surface marking of workpieces.
Additionally, it would represent a major advance in the art of
machine tools to provide a single machine tool capable of high
speed, high accuracy workpiece punching, cutting, and surface
marking wherein all functions are controllable from a central
automatic control and wherein workpiece movement is accomplished by
a single mechanism so as to eliminate the necessity of workpiece
handling between operations.
SUMMARY OF THE INVENTION
It is a principal object of this invention to provide each of the
above enumerated advances.
More specifically, it is an object of this invention to provide a
combined automatic turret punching machine tool and automatic laser
cutting tool wherein both the punching tool and the cutting tool
share a common control and a common workpiece movement system.
It is an additional specific object of this invention to provide an
automatically controlled turret punch machine tool equipped with
laser cutting abilities wherein the laser is automatically
controllable to provide workpiece surface marking in addition to
workpiece cutting.
This invention utilizes, in parts, a prior art turret punch device
which can be chosen from among those presently available
representing the best state of the art.
High speed automatically controlled turret punch machine tools
known to the art include a generally C-shaped main frame having
upper and lower arms supporting rotatable turrets in closely spaced
opposed relationship. The upper turret carries a plurality of
punching tools whereas the lower turret carries a plurality of
mating dies. A ram mechanism carried by the upper frame arm
activates the punches. The machine tool is also provided with a
work table and with moving grippers which engage peripheral edges
of a workpiece and move the workpiece over the work table with
respect to a punching station located at the ram. Frequently,
portions of the work table move with the grippers, although it has
been known to use grippers which move totally independently of the
work table. In both cases, a central portion of the work table
immediately surrounding the lower turret is generally
stationary.
Such machine tools are substantially automated and are controlled
from a central processor which may be a computer, a paper tape
reader, a hard wire sequencer, or the like. Such control systems
automatically sequence turret rotation to present the desired set
of punch and die tools at the punching station, control workpiece
gripper movement to present the desired location of the workpiece
to the punching station, and control ram movement to activate the
selected punch.
This invention provides an automatically controlled turret punch
machine tool of the above type equipped with a laser cutting tool
and a common automatically controlled workpiece movement apparatus.
The laser cutting tool includes a laser beam generator, a laser
beam pathway and a cutting head assembly. The laser beam generator
is independent of the turret punch machine tool so as to be
unaffected by the jarring vibratory operation thereof. This cutting
head assembly is mounted to the upper arm of the punch frame
overlying a portion of the stationary portion of the work table.
The stationary portion of the work table is provided with an
opening therethrough to a receptacle positioned under the work
table. The receptacle is provided with a gas evacuation system and
a debris filtering screen.
The principles of this invention are believed utilizable with many
of the machine tool punches presently available on the market, and
specifically in association with automatically controlled turret
punch machine tools such as the model 1250 available from Strippit
Division of Houdaille Industries, Inc., Akron, New York, or of the
type shown in U.S. Pat. No. 4,096,774 issued June 27, 1978, the
teaching of which are herein incorporated by reference. For reasons
which appear more fully hereinafter, the preferred laser generator
is a gas laser, particularly a CO.sub.2 laser having both
continuous output and pulsed output modes such as are generally
available, for example, from Photon Sources of Livonia, Michigan as
model 300. Laser's having outputs from between approximately 300 to
1000 watts capable of cutting sheet metal from 22 gauge to 0.5
inches or larger are preferred.
A gas supply system is provided to the cutting head allowing
selective delivery from at least two different gas sources of gas
to the cutting head. One of the gases should be chosen from those
gases which cooperate with the laser cutting beam to form an
exothermic reaction to measurably increase the cutting speed and
ability of the laser. Another of the gases is preferably of the
type which produces little or no exothermic reaction. It has been
found that by using a reduced exothermic reaction gas, particularly
in association with a pulsed laser, that it is possible to surface
mark the workpiece rather than cutting through the workpiece. This
feature provides added versatility to the overall machine tool in
that the workpiece can now be provided with desired surfaced
markings such as, for example, parts numbers, accurately positioned
gauge marks for further machining operations, surface roughened
areas and other indicia.
A common control system is provided for controlling activation of
the laser, the cutting head, the gas supply systems, the receptacle
exhaust system, the punch and associated turrets, and the workpiece
movement control. Actual laser generation may be provided by a
separate control system which is actuated from the central
automatic control. It has been found that, due to the relatively
quick actuating ability of modern laser beam generators, that the
machine tool can be cycled back and forth between usage of the
laser and usage of the punch with relativey little time delay. In
order to avoid the possibility of any damage to the cutting head
assembly during normal operation of the punch, the cutting head is
vertically movable with respect to the work table so that when it
is not in operation, it may be lifted to a free clearance position.
When in the lowered, operating position, the cutting head assembly
is equipped with roller means riding on the workpiece thereby
assuring proper spacing of the focus lens of the cutting head from
the workpiece.
It is therefore an object of this invention to provide a combined
automatically controlled turret punch and laser cutting and marking
machine tool utilizing a common automatically controlled workpiece
movement system and workpiece support table in association with
commonly controlled laser cutting head and turret punch.
Other objects, features and advantages of the invention will be
readily apparent from the following description of preferred
embodiments thereof, taken in conjunction with the accompanying
drawings, although variations and modifications may be effected
without departing from the spirit and scope of the novel concepts
of the disclosure, and in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan of the machine tool of this invention.
FIG. 2 is a side plan view, partially in section, of the machine
tool of FIG. 1 taken along lines II--II.
FIG. 3 is a fragmentary partially sectional view taken along the
lines III--III FIG. 2.
FIG. 4 is a fragmentary partially sectional view of the laser
cutting head of this invention.
FIG. 5 is an enlarged fragmentary sectional diagrammatic view of
the working end of the laser cutting head illustrating a pulse mode
operation.
FIG. 6 is a block diagram view of controls for the machine tool of
this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
As illustrated in FIG. 1 the machine tool 10 of this invention
includes a work table 11, a main frame 12 mounting turrets 13 of a
turret punch, a workpiece movement assembly 14, a laser generator
15, a laser beam pathway 16, a laser cutting head assembly 17 and
an automatic control 18.
The workpiece movement assembly 14 includes workpiece grippers 20
mounted on a carriage 21. The grippers 20 are movable in the x
directions illustrated whereas the carriage 21 is movable in the y
directions illustrated with respect to a punch work station 23
under the control of the control 18. The laser cutting head 17 is
offset in one axis direction from the punch station 23 so that the
cutting station 24 has one common axis position with respect to the
work station 23. For example, it has been found efficient to mount
the cutting station 24 on the y-axis 18 inches offset on the x-axis
thereby simplifying workpiece movement control so that the y-axis
movement control has a common reference point for both punch
operation and laser operation. The control is provided with dual
reference points in the x-axis direction so that the reference
point for laser operation can be, for example, x-axis center point
plus 18 inches. In this manner, as will be readily apparent to
those skilled in the art, movement of the workpiece WP by the
control 18 and workpiece movement assembly 14 when in the laser
mode is greatly simplified.
By mounting the laser generator 15 remote from the main frame 12,
it is assured that the jarring and vibration caused during
operation of the punch will not adversely affect the highly
sensitive laser generator. A laser beam pathway is provided through
the use of beam benders 30 which, in the embodiment illustrated,
with the laser generator mounted to the rear of the main frame 20,
first bend the laser beam 31 in a direction parallel with the
longitudinal axis of the main frame to a point immediately above
the cutter head and then bend the beam at a right angle downwardly
towards the work table 11. Such beam benders are commercially
available and, for example, model 452 beam bender assembly
available from Photon Sources, Livona, Michigan have been found
adequate. The beam pathway can be enclosed by a ducting or conduit
16a. The control 18 is also located remote from the main frame 12
and control conduit 33 is provided coupling the control 18 to the
control panel 35 of the machine tool and to the control panel 36 of
the laser beam generator.
As best shown in FIGS. 2, 3 and 4, the cutting head assembly 17 is
mounted to a flange area 40 of the main frame 12 extending to the
side in front of and above the turrets 13. The flange 40 is
positioned above a stationary portion 11a of the work table 11. The
cutting head assembly is mounted on a mounting plate 41 bolted to
the flange as at 42. A pair of spaced apart guide rods 44 are
received in bushings 45 affixed to a movable mount 46, the guide
rods being firmly affixed to the plate 41. In this manner the mount
46 is vertically movable and a hydraulic cylinder 47 attached to
plate 41 has a power arm 48 affixed to the member 46. In this
manner the major portions of the cutting head assembly can be
raised and lowered with respect to the workpiece WP. The cutting
head assembly includes a flexible conduit or coupling member 50
allowing movement of portions of the cutting head assembly upwardly
and downwardly with respect to the frame and stationary beam
bender.
The cutting head assembly terminates in a tip 52 having a cutting
end aperture 53 aligned with a focusing lens system 54 positioned
below the flexible coupling 50. Beam bender 30 is positioned above
the coupling 50 and may be affixed to and carried by the main
frame. In this manner a laser beam moving through pathway conduit
16 in the direction illustrated by arrow 60 of FIG. 4 is bent by
the beam bender 30, which may be a mirror, downwardly through the
cutting head, which has a hollow interior, through the focusing
lens 54 to the tip aperture 53. A shield 61 surrounds the tip and
carries a plurality of anti-friction balls 62 at its under surface.
The balls 62 ride on the workpiece WP maintaining the lens system
54 at a predetermined distance from the tip of the workpiece.
The cutting head assembly has a hollow conduit portion 64
intermediate the tip 52 and the lens 54. The hollow conduit portion
64 has gas entrance channel 65 to which gas lines 67 and 68 are
coupled through a selector valve 66 and appropriate fittings. The
gas lines 67 and 68 are in turn coupled with gas supply source
valves 69 and 70 which in turn are in communication with pressured
gas sources (not shown). The gas sources for lines 67 and 68 are
different with one gas source providing, preferably, a good
exothermic reaction during cutting. Such a gas source might, for
example, be oxygen while the other gas source preferably provides a
lesser or no exothermic reaction. In practice the second gas source
might, for example, be air or, if desired, an inert gas.
Positioned immediately below the tip 52 is an aperture 71 in the
stationary portion 11a of the work table 11. A flanged conduit tube
73 of larger internal diameter than the aperture 71 is affixed to
the under surface of the work table 11a aligned with the aperture
71. The conduit 73 extends downwardly into a waste recepticle 74
having a hollow chamber extending upwardly for some distance along
the length of the conduit 73, the chamber being larger than the
conduit. A gas evacuation system such as a blower 76 is ported to
the chamber surrounding the conduit 73 through a filter 77a which
may, for example, be a metal screen. The chamber surrounding the
conduit 73 is in turn in communication with a larger bottom chamber
77 below the end of tube 73, which may include a removable drawer,
for deposit of debris generated during cutting operations.
As previously explained the center line 24 of the cutting head
assembly is paralled to the punch station center line 23 and is
spaced therefrom approximately 18 inches in the x-axis direction
while being aligned in the y-axis direction. It has been found that
this 18 inch spacing allows clearance of the cutter head assembly
with respect to the periphery of the turrets while still
maintaining the cutter head assembly overlying the stationary
portion of the work table.
FIG. 4 illustrates operation of the system with the laser in a
continuous mode wherein the workpiece WP is being cut through by
the laser. FIG. 5 schematically illustrates operation of the laser
in a pulse mode where the workpiece WP is being surface marked by
the laser to a depth less than the thickness of the workpiece. It
has been found that by proper control of the laser and the gas
supply, the laser can be utilized for both workpiece cutting and
workpiece surface scribing. Since the workpiece movement control is
capable of simultaneous movement on both axes, substantially any
shape marking or cut can be accomplished with the laser.
FIG. 6 illustrates by a block diagram layout, a simplified view of
the controls for the machine tool of this invention. The controls
include the central NC controller 18, the laser associated controls
36 and various command and feedback sensors and valves. For
purposes of illustration only, the central control 18, which may
include a micro-processor or the like, can be pictured as having
three sections; 18a for control of the laser, 18b for control of
the workpiece movement apparatus and 18c for control of the punch
including the ram and turrets. The section 18a includes a mode
selector 100, a gas selector 102, an overall laser control 103 and
a safety stop on/off section 104. The workpiece movement control
includes a location section 105 which stores information relative
to the present location of the workpiece movement apparatus and the
like, a workpiece actuator 106 and may also include a time delay
107 which may also be a part of section 18a. The section 18c
includes punch ram controls 108 and turret rotation controls 109.
The laser includes a pulse mode section 111 and a continuous mode
section 112 as well as a laser beam generator section 113. The
pulse mode section includes time controls 114 for controlling both
the timing between pulses and the duration of pulses.
The mode selector 103 is utilized to select between laser pulse
operation or continuous operation. It may provide the necessary
inputs by any desired means and, for example, in the diagrammatic
view is shown as providing an input 120 to the gas selector 102
which in turn provides inputs either to gas control valve 70 or gas
control valve 69 which in turn provide inputs either to the pulse
mode or the continuous mode for setting the laser generator 113.
The mode control may activate the time delay 107. The time delay
107 is activated only when the laser is in the cut or continuous
mode and functions to delay actuation of the workpiece movement
assembly 14 by a preselected amount. This is to enable the laser to
cut through the workpiece prior to initiation of movement of the
workpiece. It has been found that the laser takes a longer quantum
of time to make an initial through-cut than it does to cut an equal
amount of material after the initial through-cut has been made.
When the mode has been selected and either valve 70 or valve 69
have been opened supplying gas to the cutting head 17, and either
activating or not activating the time delay 107, the laser control
103 is activated. Laser control 103 activates the laser generator
113 through safety on/off 104. Safety on/off 104 receives
information feedback from the gas lines as at 121 creating an all
stop condition if a low pressure is sensed. The laser control 103,
also operates the cutting head position. That provides a feedback,
as at 126 to the safety on/off 104 such that the laser generator
113 cannot be activated in the cutting head up position. The
cutting head thus must be lowered before activation of the laser,
the blower 76 may be activated as a result of lowering of the
cutting head or may be controlled by the gas system. Laser
activation also, as indicated at 127 inhibits actuation of the ram.
If desired an inhibitor signal can also be provided to the turret
control 109, however, since the laser does not in any way interfere
with the turret, turret selection for rotation of the next tool set
to the punching station can be accomplished simultaneously with the
use of the laser unless it is desired to inhibit actuation of the
turret during movement of the workpiece. When a command signal sent
to the laser by line 128 fails to actuate the laser generator 113,
as, for example, during a low power situation, that failure is
inputed by line 129 to the on/off safety 104 to produce an "all
stop" condition.
It will be appreciated by those skilled in the art from the above
that modifications to the control system of existing NC turret
machine tools in order to provide for addition of laser cutting
abilities according to this invention is relatively simple. It will
further be appreciated that the time delay block 107 is not needed
when the laser is being used for surface marking and the pulse mode
is selected.
The time delay 107 is necessary for proper utilization of the
cutting mode of the laser, however, the quantum of the time delay
differs for differing materials and workpiece thicknesses.
Therefore, in a further modification of the system, the time delay
107 can be provided as a separate programmable clock function
within the controller 18. In that instance, the time delay function
may either delay activation of workpiece movement after initiation
of the laser or, may be used as a separate laser beam terminator
which, when programmed by an additional command provides automatic
laser shut off after expiration of the programmed time period.
By integrating the time delay with the laser activation, as opposed
to the workpiece movement mechanism, an additional function is
provided. Frequently workpieces must be bored with very small
diameter openings. Although extremely small diameter punches are
available, they are expensive and, in some environments have high
failure rates. Because of the very small diameter of the laser
beam, it can also be used to provide through-cuts of small
dimension.
As further shown in FIG. 6, activation of the laser by the laser
control 103 also inputs a signal 130 to the workpiece control
indicating that the cutting head has been lowered. The signal 130
may, if desired, be input directly from a micro-switch or other
sensing device associated with the cutting head. The function of
the signal 130 is to initiate a safety within the workpiece
movement control preventing movement of the workpiece grippers 20
into the area underlying the cutting head so as to prevent damage
to the grippers. This feature can alternatively be supplied by a
sensing means associated with the grippers cabable of contacting
the lowered cutting head upon movement of the grippers to a
position adjacent the cutting head. A signal from such a sensor can
then be fed back to the control either creating an all stop
condition or activating an over-riding program to terminate
operation of the laser, reposition the grippers, reactivate the
laser and continue workpiece movement.
It is to be understood that the proper design of the cutter head
will result in a very small clearance relationship between the
bottom of the cutter head shield and the top of the workpiece such
that the safety system for the grippers should be activated before
the grippers have reached a position of possible contact with the
cutter head.
FIG. 5 illustrates use of the laser in the pulse mode. It has been
found that by choosing the proper pulse duration and pulse
separation time, a continuous scroll line can be formed on the
surface of most workpieces. However, by lengthening the time
between pulses, a spaced dash marking can also be accomplished.
Actual command control for use of the laser is relatively simple
and a typical program may include the following commands:
G63-Prepare to Mark
Selects assist gas for marking and places mode of laser in
"Pulse".
G64-Prepare to Cut
Selects assist gas for cutting and places mode of laser in
"Continuous".
G.phi..phi.-Cancels G63 or G64 and places control back in
"point-to-point" positioning mode.
M63-Assist Gas On
Applies gas selected via G63 or G64 to nozzle of cutting head.
M64-Assist Gas Off.
M65-Head Down
Causes cutting head to lower to surface of work sheet.
M66-Head Up
Raises cutting head to stored up position.
M67-Beam Off
May be used to command beam off. However, the beam is automatically
turned off when axes are "IN POSITION" or when a programmed time
delay is completed.
M68-Beam On
Turns laser beam on. Command is non-modal and must be repeated each
time beam on is required.
It will be appreciated that the G commands are preparation commands
whereas the M commands are execution commands.
A typical command sequence for operation of the machine tool to
provide both a linear cut, then a workpiece movement and punch
operation, then a scribed circle and, finally, a further punch
operation might be as follows:
______________________________________ Block Commands
______________________________________ 001 G64 M63 M65 002 G.phi.4
X.phi.2 M68 003 G.phi.1 X.phi.5 Y.phi.5 M68 F008 004 M64 M66 005
G.phi..phi. X1.phi. Y1.phi. G68 006 G63 M63 M65 007 G.phi.2 X.phi.3
Y.phi.3 I.phi.3 F.phi.1.phi. M68 008 X.phi.3 Y-.phi.3 J.phi.3 M68
009 X-.phi.3 Y-.phi.3 I.phi.3 M68 010 X-.phi.3 Y.phi.3 J.phi.3 M68
011 M64 M66 012 G.phi..phi. X.phi.1 Y.phi.1 G68
______________________________________
In considering the above sequence it is to be assumed that at the
end of each block there is a block end signal instructing the
processor to read the next block. The above sequence will provide
the following control of the machine tool.
______________________________________ Block 001 G64 M63 M65 (1)
Laser mode is selected for "continuous" cutting and oxygen is
selected as assist gas (2) Gas is applied to cutting head tip (3)
Cutting head is lowered to workpiece Block 002 G04 X02 M68 (1)
Laser beam is turned on and allowed to penetrate sheet metal. After
a delay of (2) (25) = 50 milli- seconds, the laser beam is
automatically turned off Block 003 G01 X95 Y95 M68 F008 (1) Laser
beam is turned on and workpiece is moved at 80 IPM (F008) at a
45.degree. angle in the x plus and y plus direction (2) Upon
completion of the move, the laser beam is automatically turned off
Block 004 M64 M66 (1) The assist gas is turned off (2) The cutting
head is raised Block 005 G00 X10 Y10 G68 (1) The control is placed
back in a point-to-point mode (2) A 10 inch move in x and y takes
place (3) After completion of this move, a "punch" operation (G68)
takes place Block 006 G63 M63 M65 (1) Laser mode is selected for
"Pulse" and air is selected as assist gas in preparation for
marking (2) Gas is turned on and applied to tip (3) Cutting head is
lowered Block 007 G02 X03 Y03 I03 F010 M68 (1) Laser beam is turned
on and workpiece moves in circular arc at a rate of 100 IPM along
the path (2) After completion of this arc, laser beam is turned off
Block 008 Circle is completed with update of tape Block 009
information occurring at the end of each Block 010 quarter circle
Block 011 M64 M66 (1) Asisst gas is turned off (2) Cutting head is
raised Block 011 G00 X01 Y01 G68 (1) The control is placed back in
point-to-point mode and motion is x and y is followed by "punch"
operation ______________________________________
Although not shown on the drawings, it will be apparent to those
skilled in the art that the various systems herein include
necessary equipment such as pressure sensors in the gas supply
systems, position sensors, such as micro-switches in the cutting
head assembly, and the like.
It further should be appreciated that the laser cutting head is
substantially shock isolated from the punch frame although mounted
on and carried by the punch frame. To this end, the air cylinder 47
operates in the manner of a hydraulic cushion. Additionally the
bars 44 may be provided with both top and bottom springs engaging
the bushings 45. The springs cooperate with the air cylinder
support to shock isolate the cutting head. This is desirable in
view of the fact that the focusing lens system 54 is provided in
the cutting head and, therefore, is carried by the machine tool
rather than being provided in the isolated beam generator.
It will therefore be seen from the above that our invention
provides a machine tool having automatically controlled punching,
cutting and surface marking capabilities utilizing either a turret
punch assembly or a laser cutting assembly each of which share a
common workpiece movement control.
Although the teachings of my invention have herein been discussed
with reference to specific theories and embodiments, it is to be
undertood that these are by way of illustration only and that
others may wish to utilize my invention in different designs or
applications.
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