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Claims  |
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What is claimed is:
1. A tracer control system, for a tracer head which traces the surface of a
model and outputs data signals representative of the model traced, in
which the tracing direction and feedrate of the tracer head are calculated
from said data signals derived from said tracer head, and in which said
tracing direction and said feedrate are used to achieve tracing controls;
the tracer control system comprising an input device for externally
inputting input data defining a desired tracing operation, a memory means,
operatively connected to said input device, for storing said input data,
and a processor means, operatively connected to said memory means and said
tracer head for reading said input data defining a desired tracing
operation and for controlling a tracing path wherein the data stored in
said memory means includes desired feed rate data and desired position
data for defining the desired tracing operation, wherein the data stored
in said memory means is modified by rewriting the content of said memory
means, and wherein the content of said memory means may be modified during
the tracing operation.
2. A tracer control system according to claim 1, wherein when operating in
a manual feed mode, the data stored in the memory means includes position
data for defining a desired tracing operation, and wherein said position
data is manually inputted as current position data.
3. A tracing machine, having a tracer control system and a cutting means
for cutting a workpiece, comprising:
data processing means for receiving, storing and outputting data defining a
desired tracing operation;
tracer control means, operatively connected to said data processing means,
for receiving an output from said data processing means and for providing
a plurality of output control signals;
tracing means, operatively connected to said tracer control means and said
data processing means, for tracing a model and cutting a workpiece, for
providing a plurality of displacement signals to said tracer control
means, and for providing a tracer head position signal to said data
processing means;
wherein said data processing means comprises:
operator panel means for manually providing an adjusted speed signal for
adjusting the speed of said tracing operation;
a data input unit, operatively connected to said operator panel means, for
receiving said adjusted speed signal and said data defining said desired
tracing operation;
a keyboard means, operatively connected to said data input unit, for
manually inputting said data defining said desired tracing operation;
a memory means, operatively connected to said data input unit, for storing
said data defining said desired tracing operation and said adjusted speed
signal;
a central processing unit, operatively connected to said memory means and
said data input unit, for outputting said data defining said desired
tracing operation and said adjusted speed signal;
a data output unit, operatively connected to said central processing unit
and said keyboard means, for outputting said data defining said desired
tracing operation and said adjusted speed signal, said data defining said
desired tracing operation including approach axis data, lowering speed
data, reference displacement data, approach direction data and approach
speed data;
and wherein said tracer control means comprises:
a displacement calculation circuit, operatively connected to said tracing
means, for receiving said plurality of displacement signals and for
providing a composite displacement signal output;
an indexing circuit, operatively connected to said data output unit and
said tracing means, for receiving said plurality of displacement signals
and for providing a pair of displacement direction signals at its output;
a first digital to analog converter, operatively connected to said data
output unit, for receiving said reference displacement data and for
providing a first analog output representative of said reference
displacement data;
an adder circuit, operatively connected to said first digital to analog
converter and to said displacement calculation circuit, for providing a
difference signal output representative of the difference between said
composite displacement signal output and said first analog output;
a second digital to analog converter, operatively connected to said data
output unit, for receiving said lowering speed data and for providing a
second analog output;
a first velocity control circuit, operatively connected to said adder, for
receiving said difference signal output and for providing a reference
direction speed signal output;
a second velocity control circuit, operatively connected to said adder,
said data output unit, and said second digital to analog converter, for
receiving said second analog output and said difference signal output and
for providing a tangential direction speed signal output;
a comparator circuit, operatively connected between said first velocity
control circuit and said data input unit, for providing an approach end
signal output to said input unit when said difference signal output equals
zero;
a distribution circuit, operatively connected to said first and second
velocity control circuits and said indexing circuit, for receiving said
reference direction speed signal output, said tangential direction speed
signal output, and said pair of displacement direction signals, and for
providing command speed signals at its output;
a manual operation control circuit, operatively connected to said data
output unit, for providing an alternative manual mode of operation;
an analog gate circuit, operatively connected to said first velocity
control circuit, said distribution circuit, and said manual operation
control circuit, for receiving said command speed signals and said
reference direction speed signal output, and for providing a gated command
speed signal output;
first, second and third amplifiers, operatively connected to said analog
gate circuit, for receiving said gated command signal output and for
providing first, second and third amplified outputs;
and wherein said tracing means comprises:
first, second and third servo motors, operatively connected to said first,
second and third amplifiers, respectively, said first, second and third
servo motors selectively driven in response to said gated command signal
output;
a tracer member, having a tracer head and said cutter means, operatively
connected to said first, second and third servo motors, and to said
displacement calculation circuit, said tracer head and said cutter means
moved by said first, second and third servo members;
first, second and third position detector means, operatively connected to
said first, second and third servo motors, respectively, for detecting the
position of said tracer head and for providing first, second and third
pulse outputs, respectively;
first, second and third reversible counters, operatively connected to said
first, second and third position detectors, respectively, and operatively
connected to said data input unit, for counting said first, second and
third pulse outputs and for providing a current position output to said
data input unit, whereby said data defining a desired tracing operation is
outputted from said data output unit and said tracer control means
controls said tracing means in dependence upon said data defining said
desired tracing operation.
4. A tracing machine, having a tracer control system and a cutting means
for cutting a workpiece, comprising:
data processing means for receiving, storing and outputting data defining a
desired tracing operation;
tracer control means, operatively connected to said data processing means,
for receiving an output from said data processing means, and for providing
a plurality of output control signals;
tracing means, operatively connected to said tracer control means and said
data processing means, for tracing a model and cutting a workpiece, for
providing a plurality of displacement signals to said tracer control
means, and for providing a tracer head position signal to said data
processing means;
wherein said data processing means comprises:
operator panel means for manually providing an adjusted speed signal for
adjusting the speed of said tracing operation;
a data input unit, operatively connected to said operator panel means and
to said tracing means, for receiving said adjusted speed signal and for
receiving said data defining said desired tracing operation;
a keyboard means, operatively connected to said data input unit, for
manually inputting said data defining said desired tracing operation;
a memory means, operatively connected to said data input unit, for storing
said data defining said desired tracing operation and said adjusted speed
signal;
a central processing unit, operatively connected to said memory means and
said data input unit for outputting said data defining said desired
tracing operation and said adjusted speed signal;
a data output unit, operatively connected between said central processing
unit and said tracer control means for providing said data defining said
desired tracing operation and said adjusted speed signal to said tracer
control means, whereby said data defining said desired tracing operation
is outputted from said data output unit and said tracer control means
controls said tracing means in dependence upon said data defining the
desired tracing operation.
5. A tracing machine as set forth in claim 4, wherein said tracer control
means comprises:
a displacement calculation circuit, operatively connected to said tracing
means, for receiving said plurality of displacement signals and for
providing a composite displacement signal output, wherein said data
defining said tracing operation includes approach axis data, lowering
speed data, reference displacement data, approach direction data, and
approach speed data.
6. A tracing machine as set forth in claim 5, wherein said tracer control
means further comprises:
an adder circuit, operatively connected to said data output unit and to
said displacement calculation circuit, for providing a difference signal
output representative of the difference between said composite
displacement signal output and said reference displacement data;
a comparator circuit, operatively connected between said displacement
calculation circuit and said data input unit, for providing an approach
and signal output to said data input unit when said difference signal
output equals zero;
a distribution circuit, operatively connected to said displacement
calculation circuit, for providing command speed signals at its output;
a manual operation control circuit, operatively connected to said data
output unit, for providing an alternative manual mode of operation;
an analog gate circuit, operatively connected to said distribution circuit,
said data output unit, said tracing means, and said manual operation
control circuit, for receiving said common speed signals and for providing
a gated command speed signal output to said tracing means.
7. A tracing machine as set forth in claim 6, wherein said tracing means
comprises:
a tracer member, having a tracer head and said cutter means, operatively
connected to said analog gate circuit, for performing a tracing operation
and cutting a workpiece;
position detector means, operatively connected between said tracer member
and said data input unit, for detecting the position of said tracer head
and for providing said tracer head position signal. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a tracer control system which enables arbitrary
setting of the tracing path of a tracer head.
2. Description of the Prior Art
In conventional tracer control systems, limit switches are provided for
defining the tracing path of a tracer head, for example, the range of
tracing in the x-y plane. The limit switches are actuated by the movement
of a tracing machine, by which a predetermined pick feed is carried out
and then the direction of tracing is reversed, thus performing the tracing
operation. By repeating such operations to trace a model with a stylus of
a tracer head, a workpiece is machined. Accordingly, the positions of the
limit switches must be adjusted in accordance with the size of the model,
and the limit switches are mechanically actuated, so that the reliability
of the tracing operation is relatively low.
SUMMARY OF THE INVENTION
This invention is to provide a tracer control system which is free from the
abovementioned defects of the prior art and in which data for a tracing
operation is previously inputted and stored in a memory to control the
tracing path and in which the tracing path can be set, as desired, in
accordance with a change in input data.
Briefly stated, in the tracer control system of this invention, data
defining the tracing operation is inputted from an input device and stored
in a memory, and the stored data is read out by a processor which controls
the tracing path of a tracer head tracing a model. The tracing operation
can be changed by modifying the stored data in the memory. Data defining
the tracing operation, which is obtained by a manual feed, can also be
stored in the memory.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram illustrating an embodiment of this invention;
FIG. 2 is a schematic diagram explanatory of an example of a tracing path;
FIG. 3 is a flowchart explanatory of the operation of the embodiment of
this invention; and
FIG. 4 is a schematic diagram explanatory of the tracing path in another
embodiment of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates in block form an embodiment of this invention. Reference
characters DG and IND respectively indicate a displacement calculation
circuit and an indexing circuit which are both supplied with displacement
signals .epsilon..sub.x, .epsilon..sub.y and .epsilon..sub.z derived from
a tracer head TR; ARN and ART designate speed control circuits; ADD
identifies an adder; DC denotes a distribution circuit; COMP represents a
comparator; GC shows an analog gate circuit; DRVX, DRVY and DRVZ refer to
amplifiers; MX, MY and MZ indicate servomotors; PCX, PCY and PCZ designate
position detectors; MDL identifies a model for machining; ST denotes a
stylus; CT represents a cutter; W shows a workpiece; MAC refers to a
tracing machine; CONTX, CONTY and CONTZ indicate reversible counters each
of which counts pulses from each of the position detectors PCX, PCY and
PCZ to indicate the current tracer head position; MAN designates a manual
operation control circuit; OPP identifies an operator panel; RS denotes a
setting dial for the tracing speed, etc.; BT1 and BT2 represent push
buttons; KB shows a keyboard; DSP refers to a display unit; DI indicates a
data input unit; MEM designates a memory composed of a data memory M1 and
a control program memory M2; DO identifies a data output unit; CPU denotes
a processor; and DA1 and DA2 represent D-A converters.
In accordance with displacement of the stylus ST held in contact with the
model MDL, the displacement signals .epsilon..sub.x, .epsilon..sub.y and
.epsilon..sub.z from the tracer head TR are applied to the displacement
calculation circuit DG and the indexing circuit IND to derive therefrom a
composite displacement signal .epsilon.=.sqroot..epsilon..sub.x
2+.epsilon..sub.y 2+.epsilon..sub.z 2 and displacement direction signals
sin .theta. and cos .theta., respectively. The composite displacement
signal .epsilon. is provided to the adder ADD to obtain a difference
.DELTA..epsilon. between the signal .epsilon. and a reference displacement
signal .epsilon..sub.0. The output from the adder ADD is supplied to the
velocity control circuits ARN and ART to produce a reference direction
speed signal V.sub.N and a tangential direction speed signal V.sub.T,
respectively. The output signals V.sub.N and V.sub.T from the speed
control circuits ARN and ART are both applied to the distribution circuit
DC to derive therefrom command speed signals based on the displacement
direction signals sin .theta. and cos .theta. supplied from the indexing
circuit IND. The command speed signal is applied to the analog gate
circuit GC and then provided to that one of the amplifiers DRVX, DRVY and
DRVZ which is selected by the analog gate circuit GC. The servo motors MX,
MY and MZ are selectively driven in response to the command speed signal
to operate the cutter CT and the tracer head TR together. Since the
abovementioned operation is well-known in the art, no detailed description
will be given.
In this invention, data for the tracing operation is inputted from the
keyboard KB and stored in the memory MEM, from which the stored data is
read out as the tracing operation proceeds, thereby controlling the
tracing path. Thus, this invention dispenses with limit switches, which
are required in the prior art, and permits easy setting and modification
of the tracing path. By way of example, the input data may be such as
shown in the following table.
TABLE 1
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Item Symbol Code
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Mode (Refer to A01
table 2)
Reference displace-
.epsilon..sub.o
A02
ment value
Approach axis X, Y, Z A03
Approach direction
+, - A04
Approach speed V.sub.AP F1
Tracing direction +, - A05
Tracing speed V.sub.TF F2
Pick feed direction
+, -
Pick feed speed V.sub.PF F3
Pick feed value P A06
Tracing stroke limit
L.sub.P X1
Tracing stroke limit
L.sub.N X2
Tracing control end
L.sub.TE Y1
Automatic return ON, OF A07
Automatic return speed
V.sub.AR F4
Automatic return L.sub.RP Z1
position
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TABLE 2.
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Mode Submode
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1 Manual tracing
2 Forward/reverse scan
tracing 45 degree tracing
3 Partial contour
tracing
4 360 degree contour
Axial pick feed
tracing Z-axis pick feed
5 Partial contour
tracing
6 3-dimensional
tracing
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In the case of achieving such a tracing operation as shown in FIG. 2 in
which the tracing operation starts from the point A towards the point a
and proceeds via the route [a-b-c- . . . u-v], with the tracing stroke
limit L.sub.P =X1,L.sub.N =X2, the pick feed value=P, the tracing control
end L.sub.TE =Y1 and the automatic return position L.sub.RP =Z1, and then
the tracing operation is automatically returned from the tracing control
end Y1 to the position Z1, control is performed in accordance with the
flow-chart shown in FIG. 3.
Upon depression of an approach button (not shown), the processor CPU reads
out data of the approach axis, the approach direction and the approach
speed from the memory MEM to apply a signal via the data output unit DO to
the analog gate circuit GC to actuate the amplifier DRVZ, causing the
servo motor MZ to lower the tracer head TR and the cutter CT. The lowering
speed of the tracer head TR and the cutter CT can be determined by data
supplied via the data output unit DO to the D-A converter DA2.
Before the stylus ST is lowered into contact with the model MDL, the
deflection signals .epsilon..sub.x, .epsilon..sub.y and .epsilon..sub.z
are zero, so that the difference signal .DELTA..epsilon. remains equal to
the nominal deflection signal .epsilon..sub.0. When the stylus has been
brought into contact with the model and the signal .epsilon. has become
equal to the reference displacement signal .epsilon..sub.0, the comparator
COMP detects that .DELTA..epsilon.=0, and provides an approach end signal
AE to the data input unit DI. When the processor CPU has read the approach
end signal AE to detect completion of the approach, the tracing operation
is initiated.
Upon starting of the tracing operation, the processor CPU reads data of the
tracing mode, the reference displacement value, the tracing direction and
the tracing speed to start tracing control. The reference displacement
data is converted by the D-A converter DA1 into the reference displacement
signal of an analog form for input to the adder AND. The servo motor MX is
driven in the direction dependent upon the tracing direction data. The
processor CPU also reads out the tracing stroke limits L.sub.P and L.sub.N
from the memory MEM to compare them with the content of the reversible
counter CONTX indicating the current position of the stylus ST.
For instance, in a one-way tracing operation, when the content of the
reversible counter CONT X is equal to the tracing stroke limit L.sub.N,
the axis is switched, and the processor CPU reads data of the pick feed
direction, the pick feed rate and the pick feed value P to control the
pick feed. When the content of the reversible counter CONT Y has become
equal to the pick feed value P after starting of the pick feed, the
processor CPU achieves a tracing return operation, i.e. tracing in the +
direction. Further, the processor CPU reads the tracing control end
position L.sub.TE to detect whether or not the tracing has reached there
during the pick feed operation.
If it is detected that the tracing has reached the tracing control end
position L.sub.TE during the pick feed operation, the processor CPU reads
out the data of the automatic return, the automatic return speed and the
automatic return position L.sub.RP from the memory MEM, and based on the
data of the automatic return being ON, the servo motor MZ is driven, and
when the content of the reversible counter CONTZ becomes equal to the
value of the automatic return position L.sub.RP, the tracing control is
completed.
The data of the tracing stroke limits L.sub.P and L.sub.N, the tracing
control end position L.sub.TE, the automatic return position L.sub.RP and
the pick feed value P, mentioned above, need not always be inputted from
the keyboard KB but may also be set in the memory MEM. That is, the
contents of the reversible counters actually obtained in the case of
tracing in the manual feed mode are set in the memory MEM.
Also it is possible to rewrite the data of the memory MEM during the
tracing operation. In other words, the tracing path can be modified at any
time. The rewrite is achieved, for example, by modifying input data from
the keyboard KB which is read and displayed on the display unit DSP. Thus,
the pick feed start position, that is, the tracing stroke limit L.sub.P or
L.sub.N, can be easily changed. In the case of changing the tracing speed,
the push button BT1 on the operator panel OPP is depressed to provide an
override and when the tracing speed has been adjusted by the actuation of
the setting dial RS to a value which is considered to be optimum for the
cutter CT, the push button BT2 is depressed to write the speed data in the
memory MEM. Thereafter, the tracing takes place at the newly set speed.
Also in the case of performing partial tracing, for example, from a start
point S1 to an end point E1 and from a start point S2 to an end point E2,
as shown in FIG. 2, tracing control can be achieved continuously by
predetermining the pick feed value and the tracing stroke limits for each
area of tracing. Moreover, modes of tracing operation can also be set so
that scan tracing is followed by contour tracing.
As has been described in the foregoing, in the present invention, data
defining tracing operations, such as shown in Tables 1 and 2, are inputted
from the keyboard KB and stored in the memory MEM and then read out
therefrom to perform arithmetic operations, decision operations, etc.
under the control of the processor CPU, thereby controlling the tracing
path. This invention does not require any mechanical limit switches, and
hence provides for enhanced reliability in tracing and permits a desired
setting of the tracing path. Furthermore, the tracing path can be changed
by rewriting the content of the memory MEM during tracing, so that tracer
machining can be achieved under optimum conditions.
It will be apparent that many modifications and variations may be effected
without departing from the scope of the novel concepts of this invention.
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