Nozzle movement system for laser machining equipment

Disclosed is a nozzle movement system for a laser machining equipment for moving the nozzle of a CNC laser machining equipment when carrying out a three-dimensional machining of a machining surface of a workpiece. A hand coordinate system composed of the axial direction of the nozzle and the plane perpendicular to the axis of the nozzle is provided, and a movement command on the hand coordinate system is output by using a machine operation panel (31). A matrix creation means (38) creates a conversion matrix from the hand coordinate system to a basic coordinate system, based on the rotational position data stored in registers (39a, 39b) of an .alpha.-axis and .beta.-axis exhibiting the attitude of the nozzle. A coordinate conversion means (37) converts movement commands (.DELTA.xh, .DELTA.yh and .DELTA.zh) on the hand coordinate system to amounts of movement (.DELTA.x, .DELTA.y and .DELTA.z) on the basic coordinate system, by using the conversion matrix, and moves the nozzle. With this arrangement, the nozzle can be simply moved without changing the distance between the nozzle and the machining surface of a workpiece. Further, the distance between the nozzle and the workpiece can be adjusted by moving the nozzle perpendicularly with respect to the machining surface.

DESCRIPTION 
1. Technical Field 
The present invention relates to a nozzle movement system for a laser 
machining equipment, by which the nozzle of a CNC laser machining 
equipment for carrying out a three-dimensional machining is moved with 
respect to a machining surface, and more specifically, to a nozzle 
movement surface for a laser machining equipment by which a nozzle can be 
easily moved along the plane surface of a workpiece. 
2. Background Art 
A NCN laser machining equipment composed of a combination of a laser 
oscillator and a numerical control apparatus (CNC) is widely used. In 
particular, a machining of a complex configuration can be carried out at a 
high speed by a non-contact system, due to a combination of the 
characteristics of the laser machining equipment by which a machining can 
be carried out at a high speed and the characteristics of the numerical 
control apparatus (CNC) by which a complex contour can be controlled. 
Particularly, a CNC laser machining equipment capable of carrying out a 
three-dimensional machining which cannot be carried out by a conventional 
punch press, nibbling machine and the like is put to practical use. 
To carry out a three-dimensional machining by the CNC laser machining 
equipment, the attitude of the nozzle at an extreme end must be 
controlled, in addition to a control of X-, Y- and Z-axes, and the control 
axes used for this purpose are referred to as an .alpha.-axis and 
.beta.-axis. The attitude of the nozzle is controlled by a zero offset 
type control or an offset type control. 
In this three-dimensional laser machining equipment, a machining program is 
created by moving a nozzle on the surfaces of an actual workpiece and 
teaching machining points. At this time, the attitude of the nozzle is 
controlled so that the nozzle is perpendicular to a machining surface of 
the workpiece, and a predetermined distance is maintained between the 
nozzle and the machining surface. This is carried out to ensure that a 
laser beam is focused on a given position on the plane surface of the 
workpiece. 
To achieve the above object, when the machining points are taught, the 
nozzle must be moved in the same direction as that in which the surface of 
the workpiece is machined, while maintaining the predetermined distance 
between the machining surface and the nozzle. Further, when the distance 
between the nozzle and the workpiece is adjusted, the nozzle must be moved 
perpendicularly with respect to the machining surface. 
Nevertheless, if the plane surface of the workpiece to be subjected to a 
three-dimensional machining is not parallel to the X-Y plane, the attitude 
of the nozzle does not coincide with the axis of a basic coordinate, i.e., 
the nozzle is inclined. Therefore, it is very difficult to control the 
movement of the nozzle by using a usual operation panel by which movements 
in the X-, Y- and Z-axis directions are carried out in a basic coordinate 
system while maintaining a predetermined distance between the nozzle and 
the machining surface of the workpiece. Further, it is very difficult to 
adjust the distance between the nozzle and the machining surface by using 
the usual operation panel. 
DISCLOSURE OF THE INVENTION 
Taking the above into consideration, an object of the present invention is 
to provide a nozzle movement system for a laser machining equipment, by 
which a nozzle can be moved while maintaining a predetermined distance 
between the nozzle and the machining surface of a workpiece. 
To attain the above object, according to the present invention, there is 
provided a nozzle movement system for a laser machining equipment, for 
moving the nozzle of a CNC laser machining equipment when carrying out a 
three-dimensional machining of a machining surface, the system comprising 
a movement-command means for outputting a movement command on a hand 
coordinate system composed of the axial direction of the nozzle and the 
plane perpendicular to the nozzle, by manually feeding the nozzle on the 
hand coordinate system, a matrix creation means for creating a matrix for 
converting the movement command to an amount of movement on a basic 
coordinate system based on the rotational position data of an .alpha.-axis 
and .beta.-axis for controlling the attitude of the nozzle, and a 
coordinate conversion means for converting the movement command to the 
amount of movement by using the matrix. 
The movement command means provides the hand coordinate system composed of 
the axial direction of the nozzle and the plane perpendicular to the axis 
of the nozzle, and outputs the movement command on the hand coordinate 
system. The movement command means can be arranged as a machine control 
panel. The matrix creation means creates the conversion matrix from the 
hand coordinate system to the basic coordinate system, based on the 
rotational position data of the .alpha.-axis and .beta.-axis exhibiting 
the attitude of the nozzle. The coordinate conversion means converts 
movement commands on the hand coordinate system to amounts of movement on 
the basic coordinate system by using the conversion matrix, and moves the 
nozzle. With this arrangement, the nozzle can be easily moved without 
changing the distance between the nozzle and the machining surface of a 
workpiece, and further, the distance between the nozzle and the workpiece 
can be adjusted by moving the nozzle perpendicularly with respect to the 
machining surface.

BEST MODE OF CARRYING OUT THE INVENTION 
An embodiment of the present invention will be described below with 
reference to the drawings. 
FIG. 2 shows the relationship between a workpiece and a nozzle. The 
machining surface 102a of a workpiece 12 is inclined with respect to the 
X-Y plane 101 of a basic coordinate system, and therefore, the attitude of 
the nozzle 103 is controlled to be made perpendicular to the machining 
surface 102a. 
Here, the coordinate system formed by the machining surface 102a and the 
axis of the nozzle 103 is defined as a hand coordinate system and the 
coordinate axes thereof are represented by Xh, Yh and Zh, and the 
coordinate axes of the basic coordinate system are represented by X, Y and 
Z. 
For example, when a machining is carried out along a locus 104 on the 
machining surface 102a, the nozzle 103 must be moved so that a distance 
.DELTA.l between the nozzle 103 and the machining surface is maintained at 
a predetermined amount. This is carried out to ensure that the focus of a 
laser beam is at a desired depth from the machining surface 102a. 
Therefore, when the nozzle 103 can be moved on the hand coordinate system, 
the nozzle 103 need only be moved on the Xh-Yh plane of the hand 
coordinate system. Further, when the distance .DELTA.l between the nozzle 
103 and the machining surface 102a must be changed, the nozzle 103 need 
only be moved in the direction of the coordinate axis Zh. More 
specifically, according to the present invention, the movement of the 
nozzle 103 is controlled in such a manner that the nozzle 10 is moved on 
the hand coordinate system, and this movement is converted to the basic 
coordinate system (X, Y, Z). 
FIG. 3 is a block diagram of the hardware of a numerical control apparatus 
(CNC) for controlling a three-dimensional laser machining equipment, 
wherein 10 designates a numerical control apparatus. A processor 11, which 
serves as a central component for controlling the numerical control 
apparatus (CNC) 10 as a whole, reads a system program stored in a ROM 12 
through a bus 21 and controls the numerical control apparatus (CNC) 10 as 
a whole according to the system program. A RAM 13 stores temporary 
calculation data, display data and the like; an SRAM is used as the RAM 
13. A CMOS 14 stores laser machining conditions, amounts of pitch error 
correction, machining programs, parameters and the like. This data is 
maintained as is even after a power supply to the numerical control 
apparatus (CNC) 10 is cut off, because the CMOS 14 is supplied with power 
from a battery and is a non-volatile memory. 
An interface 15 is connected to a machine operation panel 13 that outputs 
teaching data as a moving command on the hand coordinate system. The 
operation of the machine operation panel 31, and the movement command, 
will be described later in detail. 
A programmable machine controller (PMC) 16 is incorporated in the CNC 10, 
and control a machine in accordance with a sequence program created in a 
ladder form. More specifically, the programmable machine controller (PMC) 
6 uses the sequence program to convert the command for an auxiliary gas 
and the like instructed by the machining program to a signal needed by the 
machine, and output same to the machining through an I/O unit 17. This 
output signal actuates magnets and the like, hydraulic valves, pneumatic 
valves, electric actuators, and the like of the machine. Further, the 
programmable machine controller (PMC) 16 receives signals from the limit 
switches and the machine operation panel of the machine, and supplies same 
to the processor 11 after a necessary processing of same. 
A graphic control circuit 18 converts digital data such as the present 
position of each axis, alarms, parameters, image data and the like to 
image signals and outputs same. These image signals are supplied to the 
display unit 26 of a CRT/MDI unit 25 and displayed thereat. An interface 
19 receives data from the keyboard 27 in the CRT/MDI unit 25 and supplies 
same to the processor 11. 
An interface 20 is connected to a manual pulse generator 32 and receives 
pulses therefrom. 
Each of the axis control circuits 41 to 45 receives a movement command for 
each axis from the processor 11, and outputs a command for each axis to 
each of the servo amplifiers 51 to 55, whereupon each of the servo 
amplifiers 51 to 55 receives the movement command and drives each of the 
servo motors 61 to 65 for the respective axes. Here, the servo motors 61 
to 65 drive the X-axis, Y-axis, Z-axis, .alpha.-axis and .beta.-axis. Each 
of the servo motors 61 to 65 contains a position detecting pulse coder, 
and position signals from the pulse coder are fed back as a pulse train. 
Further, this pulse train can be subjected to an F/V (frequency/speed) 
conversion to create a speed signal. The feedback line and speed feedback 
of these position signals are not shown in the Figure. 
A laser oscillating unit 80 is connected to an interface 71, and a laser 
oscillation output, oscillation frequency, pulse duty and the like are 
output therethrough by the numerical control apparatus 10. The laser 
oscillating unit 80 outputs a laser beam in accordance with these 
commands, and the laser beam is introduced to the nozzle and then focused 
on the workpiece for machining same. 
FIG. 4 is a partial arrangement diagram of an offset type nozzle head 
mechanism. An .alpha.-axis servo motor 1 drives the .alpha.-axis and a 
.beta.-axis servo motor 2 drives the .alpha.-axis. The laser beam 3 is 
introduced to the extreme end of a nozzle by a not shown reflection 
mirror, and irradiated to the workpiece. 
The .alpha.-axis is a rotation axis rotating about the Z-axis, and the 
rotation of the .alpha.-axis servo motor 1 causes a member 5 to be rotated 
of the .alpha.-axis servo motor 1 causes a member 5 to be rotated through 
gears 4a and 4b to thus control the rotation of the nozzle. The rotation 
of the .beta.-axis servo motor 2 causes an axis 7 to be rotated through 
gears 6a and 6b, and the rotation of the axis 7 causes an axis 9 to be 
rotated and controlled through bevel gears 8a and 8b. Designated at 9a is 
the nozzle fixed to the axis 9. 
FIG. 5 is a diagram explaining a method of determining a conversion matrix 
for converting the hand coordinate system to the basic coordinate system, 
wherein the nozzle is rotated by .alpha..degree. on the X-Y plane and the 
.beta.-axis is assumed to be rotated by .beta..degree. at tis position. 
Here, when the unit vectors of the Xh-, Yh- and Zh-axes on the hand 
coordinate system are represented on the basic coordinate system, 
respectively, by 
EQU u (u.sub.x, u.sub.y, u.sub.z) 
EQU v (v.sub.x, v.sub.y, v.sub.z) 
EQU w (w.sub.x, w.sub.y, w.sub.z), 
the respective elements are represented by 
EQU u.sub.x =cos.alpha. 
EQU u.sub.y =sin.alpha. 
EQU u.sub.z =0 
EQU u.sub.y =sin.alpha. 
EQU w.sub.x =sin.beta.*sin.alpha. 
EQU w.sub.y =sin.beta.*cos.alpha. 
EQU w.sub.z =cos.beta. 
The unit vector v of the Yh-axis can be calculated as the outer product of 
the unit vector u and the unit vector w, and therefore, the following 
expression can be obtained. 
EQU v.sub.x =w.sub.y *u.sub.z -w.sub.z *u.sub.y 
EQU v.sub.y =w.sub.z *u.sub.x -w.sub.x *u.sub.z 
EQU v.sub.z =w.sub.x *u.sub.y -w.sub.y *u.sub.x 
As a result, a conversion matrix A can be represented by the following 
expression. 
##EQU1## 
The conversion from the hand coordinate system to the basic coordinate 
system can be represented by the following expression. 
EQU [.DELTA.X.DELTA.Y.DELTA.Z].sup.T =A[.DELTA.xh.DELTA.yh.DELTA.zh].sup.T 
FIG. 1 is a block diagram of a process for converting a movement command of 
the hand coordinate system to an amount movement of the basic coordinate 
system. The machine operation panel 31 includes jog buttons 32a, 32b, 33a, 
34a and 34b for moving the nozzle in each coordinate axis direction. When 
a switch 35 is set to the left (H), these buttons output moving commands 
for the hand coordinated system, and when the switch is set to the right 
(B) conversely, these buttons output moving commands for the basic 
coordinate system. 
When the jog button 32a (+X) is operated, assuming that the changing switch 
35 is set to the left (H), a movement command .DELTA.xh can be output by 
which the nozzle is moved in the Xh-axis direction on the machining 
surface, without changing the distance between the nozzle and the 
machining surface. Further, when the button 34a (+Z) is operated, a 
movement command .DELTA.zh can be output by which the nozzle is moved in 
the Zh-axis direction perpendicular to the machining surface. Here, the 
jog button 32a and the like are operated for moving the nozzle to the next 
machining point. Next, when a switch 36 is depressed, movement commands 
.DELTA.xh, .DELTA.yh, and .DELTA.zh on the hand coordinate axis are output 
by the microprocessor contained in the machine operation panel 31. 
Conversely, the rotation angles of the .alpha.-axis and .beta.-axis are 
stored in registers 39a and 39b and a matrix creation means 38 calculates 
and determines the above conversion matrix A from these rotation angles. A 
coordinate conversion means 37 converts the movement commands .DELTA.xh, 
.DELTA.yh and .DELTA.zh from the machine operation panel 31 to the amounts 
of movement .DELTA.x, .DELTA.y, and .DELTA.z on the basic coordinate 
system, by using the matrix A, and outputs same to the axis control 
circuits 51, 52 and 53, respectively. 
As described above, the above teaching operation can be simply carried out 
without changing the distance between the nozzle and the machining surface 
in such a manner that movement commands are output on the hand coordinate 
system, and are converted to the amounts of movement on the basic 
coordinate system by the conversion matrix. Further, the nozzle can be 
moved in the direction perpendicular to the machining surface, and thus 
the distance between the nozzle and the machining surface can be easily 
adjusted. 
Although the movement command is output from the machine operation panel in 
the above description, the machine operation panel can output only an 
operation signal for the jog button, whereas a movement command on the 
hand coordinate system is created and converted to an amount of movement 
on the basic coordinate system in the numerical control apparatus. 
Further, the nozzle is described above as an offset type nozzle, but 
similar operation also can be carried out by a zero offset type nozzle. In 
this case, however, the a zero offset type conversion matrix must be 
prepared. 
As described above, according to the present invention, since a movement 
command on the hand coordinate system is output from the machine operation 
panel and converted to a movement command on the basic coordinate system 
by the conversion matrix, the position of the nozzle can be simply 
controlled without changing the distance between the machining surface and 
the nozzle. Further, the distance between the nozzle and the machining 
surface can be easily adjusted. 
Consequently, the creation of a machining program is simplified and the 
time necessary for creating the machining program is shortened.