U.S. patent number RE33,774 [Application Number 07/554,457] was granted by the patent office on 1991-12-24 for coordinate measuring and testing machine.
This patent grant is currently assigned to Wegu-Messtechnik GmbH. Invention is credited to Werner H. Gurny.
United States Patent |
RE33,774 |
Gurny |
December 24, 1991 |
Coordinate measuring and testing machine
Abstract
Multi-coordinate measuring and testing machine which is
essentially constituted from a fundamental machine unit, a scanning
or sensing system which is movable in at least two coordinate
directions, and a machine-controlling unit. The scanning or sensing
system is constructed as a multi-sensor system and is constituted
from a mechanical sensing head or probe with at least one stylus
and/or a video scanner and/or a laser scanner which are controlled
from a microprocessor and operate independently of each other, and
which are selectively either individually actuatable by means of
software connected thereto, or can be coupled to each other in a
dual or triple combination.
Inventors: |
Gurny; Werner H. (Wadgassen,
DE) |
Assignee: |
Wegu-Messtechnik GmbH
(Wadgassen, DE)
|
Family
ID: |
6348596 |
Appl.
No.: |
07/554,457 |
Filed: |
July 19, 1990 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
317617 |
Mar 1, 1989 |
04908951 |
Mar 20, 1990 |
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Foreign Application Priority Data
Current U.S.
Class: |
33/503; 33/1M;
33/505; 348/142; 356/609; 33/504; 702/168; 702/167 |
Current CPC
Class: |
G01B
11/005 (20130101); G01B 21/04 (20130101) |
Current International
Class: |
G01B
21/02 (20060101); G01B 11/00 (20060101); G01B
21/04 (20060101); G01B 007/03 (); G01B 007/28 ();
G01B 011/03 (); G01B 011/24 () |
Field of
Search: |
;33/503,504,505,1M
;364/560,561,562 ;358/96,107 ;356/376,394 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0206744 |
|
Dec 1986 |
|
EP |
|
3616812 |
|
Nov 1987 |
|
DE |
|
3725347 |
|
Feb 1988 |
|
DE |
|
60-224009 |
|
Jul 1985 |
|
JP |
|
61-2008 |
|
Feb 1986 |
|
JP |
|
61-31909 |
|
Apr 1986 |
|
JP |
|
62-245109 |
|
May 1987 |
|
JP |
|
1277014 |
|
Jun 1972 |
|
GB |
|
2190487 |
|
Nov 1987 |
|
GB |
|
Other References
Technical Journal, Industrieanzeiger, H.103/104, 1987, p. 56. .
Technical Journal, Industrieanzeiger, No. 56, 1984, pp. 113-119,
Kap. 2.2, FIG. 3, 8. .
Technical Journal, Sensor Review, Oct. 1987, p. 174. .
Technical Journal, Technisches Messen tm, 53, 1986, pp. 286-292.
.
Technical Journal, Technische Rundschau, 40, 1985, pp.
28-37..
|
Primary Examiner: Cuchlinski, Jr.; William A.
Assistant Examiner: Gutierrez; Diego F. F.
Attorney, Agent or Firm: Wood, Herron & Evans
Claims
What is claimed is:
1. Multi-coordinate measuring and testing installation, comprising
a fundamental machine unit; a scanning system .Iadd.mounted upon
said fundamental machine unit and .Iaddend.movable in at least two
coordinate directions; and a machine control unit .Iadd.for
inputting commands for controlling operation of said scanning
system.Iaddend., said scanning system being a multi-sensor scanning
system constituted of a mechanical probe having at least one
sensing stylus, a video scanner and a laser scanner; a
microprocessor .Iadd.interconnected with said machine control unit
.Iaddend.for controlling said sensing stylus and .[.scanner.].
.Iadd.scanners .Iaddend.so as to be operable independently of each
other and being selectively actuatable .[.along.]. .Iadd.alone
.Iaddend.through software or coupleable to each other in a dual or
triple operative combination, said video scanner and the laser
scanner being arranged on a common beam path for detecting the same
measuring point on a workpiece.
2. An installation as claimed in claim 1, wherein a single said
software is provided for the actuation of the entire multi-sensor
scanning system.
3. An installation as claimed in claim 1, comprising two spindles
movable in a Z-coordinate direction, one said spindle mounting the
mechanical probe having sensing styl; and said other spindle
mounting said video scanner and said laser scanner.
4. An installation as claimed in claim 3, wherein said spindles are
arranged on a common measuring carriage.
5. .[.Am.]. .Iadd.An .Iaddend.installation as claimed in claim 3,
wherein a measuring carriage is provided for each said spindle,
said spindles being movable in synchronism and also separately of
each other in selectively the same or different coordinate
directions.
6. An installation as claimed in claim 4 or 5, wherein said laser
scanner is employable in a scanning operation and also in
autofocus.
7. An installation as claimed in claim 6, wherein said laser
scanner during scanning operation non-contactingly follows the
surface contour of a workpiece being measured at a constant
distance therefrom along the X and Y-coordinate directions, said
laser scanning system comprising .[.two.]. .Iadd.first and second
.Iaddend.interlinked closed control circuits, .[.a.]. .Iadd.said
.Iaddend.first .[.said.]. control circuit determining the
transmitting power of the laser relative to the reflective
characteristics of the workpiece and in dependence upon a receiving
signal in a receiver controlling a transmission signal in a
transmitter, and .[.the.]..Iadd.said .Iaddend.second .[.said
superimposed.]. control circuit controlling the continual follow-up
of the measuring carriage and spindle in the Z-direction into an
optimum focusing plane.
8. An installation as claimed in claim 7, wherein said receiver
includes differentiating diodes for generating a differential
signal in conformance with the focusing setting of a lens, said
Z-axis being automatically positioned through a linear amplifier
and servomotor into the focusing plane.
9. An installation as claimed in claim 7, wherein said measuring
carriage and spindle for the Z-axis includes a measuring system
with a glass measuring rod, and the present position of elevation
is conveyed to a main computer.
10. An installation as claimed in claim 1, wherein the video
scanner receives measuring points along the external contour of the
workpiece said measuring points being determined by a digitalized
picture of a respective segment of the workpiece which is generated
by a video processor, the contours of said workpiece being
determinable along the X and Y-coordinates through edge tracing
routines in the digitalized picture, and the measuring points in
the Z-direction being formed with a focusing means and the camera
picture or a high-precision laser focusing system.
11. An installation as claimed in claim 1, wherein said mechanical
probe is selectively a switching or a measuring probe.
12. An installation as claimed in claim 4 or 5, wherein the
fundamental machine unit comprises a portal-like gantry structure
having a solid base, selectively including a measuring turntable
for receiving the workpiece, and a cross-carrier supporting the
measuring carriage for the spindles for longitudinal displacement
thereon in a direction of travel at right angles or equally
directed relative to said gantry structure, said measuring carriage
or carriages and the spindle or spindles being controllable from a
control panel and the obtained results of measurement being
recordable on a picture screen of a display unit or selectively on
a printer. .Iadd.
13. Multi-coordinate measuring and testing installation, comprising
a fundamental machine unit; a scanning system mounted upon said
fundamental machine unit and movable in at least two coordinate
directions; and a machine control unit for inputting commands for
controlling operation of said scanning system, said scanning system
being a multi-sensor scanning system consisting of a mechanical
probe having at least one sensing stylus, and a non-contacting
scanner selected from the class comprising a video scanner and a
laser scanner; a microprocessor interconnected with said machine
control unit for controlling said sensing stylus and said
non-contacting scanner so as to be operable independently of each
other and being selectively actuatable alone through software or
coupleable to each other in a dual operative combination. .Iaddend.
.Iadd.
14. An installation as claimed in claim 13, wherein a single said
software is provided for the actuation of the entire multi-sensor
scanning system. .Iaddend. .Iadd.15. An installation as claimed in
claim 13, comprising two spindles movable in a Z-coordinate
direction, one said spindle mounting said mechanical probe having
said sensing stylus; and said other spindle mounting said
non-contacting scanner. .Iaddend. .Iadd.16. An installation as
claimed in claim 15, wherein said spindles are arranged on a common
measuring carriage. .Iaddend. .Iadd.17. An installation as claimed
in claim 15, wherein a measuring carriage is provided for each said
spindle, said spindles being movable in synchronism and also
separately of each other in selectively the same or different
coordinate directions.
.Iaddend. .Iadd.18. An installation as claimed in claim 16 or 17,
wherein said non-contacting scanner is a laser scanner, said laser
scanner being employable in a scanning operation and also in
autofocus. .Iaddend. .Iadd.19. An installation as claimed in claim
18, wherein said laser scanner during scanning operation
non-contactingly follows the surface contour of a workpiece being
measured at a constant distance therefrom along the X and
Y-coordinate directions, said laser scanning system comprising
first and second interlinked closed control circuits, said first
control circuit determining the transmitting power of the laser
relative to the reflective characteristics of the workpiece and in
dependence upon a receiving signal in a receiver controlling a
transmission signal in a transmitter, and said second control
circuit controlling the continual follow-up of the measuring
carriage and spindle in the Z-direction into an optimum focusing
plane. .Iaddend. .Iadd.20. An installation as claimed in claim 19,
wherein said receiver includes differentiating diodes for
generating a differential signal in conformance with the focusing
setting of a lens, said Z-axis being automatically positioned
through a liner amplifier and servomotor into the focusing plane.
.Iaddend. .Iadd.21. An installation as claimed in claim 20, wherein
said measuring carriage and spindle for the Z-axis includes a
measuring system with a glass measuring rod, and the present
position of elevation
is conveyed to a main computer. .Iaddend. .Iadd.22. An installation
as claimed in claim 13, wherein said non-contacting scanner is a
video scanner, said video scanner receiving measuring points along
the external contour of the workpiece said measuring points being
determined by a digitalized picture of a respective segment of the
workpiece which is generated by a video processor, the contours of
said workpiece being determinable along the X and Y-coordinates
through edge tracing routines in the digitalized picture, and the
measuring points in the Z-direction being formed with a focusing
means and the camera picture or a high-precision laser focusing
system. .Iaddend. .Iadd.23. An installation as claimed in claim 13,
wherein said mechanical probe is selectively a switching or a
measuring probe. .Iaddend. .Iadd.24. An installation as claimed in
claim 16 or 17, wherein the fundamental machine unit comprises a
portal-like gantry structure having a solid base, selectively
including a measuring turntable for receiving the workpiece, and a
crosscarrier supporting the measuring carriage for the spindles for
longitudinal displacement thereon in a direction of travel at right
angles or equally directed relative to said gantry structure, said
measuring carriage or carriages and the spindle or spindles being
controllable from a control panel and the obtained results of
measurement being recordable on a picture screen of a display unit
or selectively on a printer. .Iaddend.
.Iadd.25. Multi-coordinate measuring and testing installation,
comprising a fundamental machine unit; a scanning system mounted
upon said fundamental machine unit and movable in at least two
coordinate directions; and a machine control unit for inputting
commands for controlling operation of said scanning system, said
scanning system being a multi-sensor scanning system consisting of
a video scanner and a laser scanner; a microprocessor
interconnected with said machine control unit for controlling said
video scanner and said laser scanner so as to be operable
independently of each other and being selectively actuatable alone
through software of coupleable to each other in a dual operative
combination; said video scanner and said laser scanner being
arranged on a common beam path for detecting the same measuring
point on a workpiece.
.Iaddend. .Iadd.26. An installation as claimed in claim 25, wherein
a single said software is provided for the actuation of the entire
multi-sensor scanning system. .Iaddend. .Iadd.27. An installation
as claimed in claim 25, comprising a spindle movable in a
Z-coordinate direction, said spindle mounting said video scanner
and said laser scanner. .Iaddend. .Iadd.28. An installation as
claimed in claim 27, wherein said laser scanner is employable in a
scanning operation and also
in autofocus. .Iaddend. .Iadd.29. An installation as claimed in
claim 28, further comprising a measuring carriage, said spindle
being mounted on said measuring carriage, wherein said laser
scanner during scanning operation non-contactingly follows the
surface contour of a workpiece being measured at a constant
distance therefrom along the X and Y-coordinate directions, said
laser scanning system comprising first and second interlinked
closed control circuits, said first control circuit determining the
transmitting power of the laser relative to the reflective
characteristics of the workpiece and in dependence upon a receiving
signal in a receiver controlling a transmission signal in a
transmitter, and said second control circuit controlling the
continual follow-up of the measuring carriage and spindle in the
Z-direction into an optimum focusing
plane. .Iaddend. .Iadd.30. An installation as claimed in claim 29,
wherein said receiver includes differentiating diodes for
generating a differential signal in conformance with the focusing
setting of a lens, said Z-axis being automatically positioned
through a liner amplifier and servomotor into the focusing plane.
.Iaddend. .Iadd.31. An installation as claimed in claim 30, wherein
said measuring carriage and spindle for the Z-axis includes a
measuring system with a glass measuring rod, and the present
position of elevation is conveyed to a main computer. .Iaddend.
.Iadd.32. An installation as claimed in claim 29, wherein the
fundamental machine unit comprises a portal-like gantry structure
having a solid base, selectively including a measuring turntable
for receiving the workpiece, and a cross-carrier supporting the
measuring carriage for the spindles for longitudinal displacement
thereon in a direction of travel at right angles or equally
directed relative to said gantry structure, said measuring carriage
or carriages, said spindle being controllable from a control panel
and the obtained results of measurement being recordable on a
picture screen of a display unit or selectively on a printer.
.Iaddend.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a multi-coordinate measuring and
testing machine which is essentially constituted from a fundamental
machine unit, a scanning or sensing system which is movable in at
least two coordinate directions, and a machine-controlling
unit.
Multi-coordinate measuring and testing machines of that type are
counted as being within the general state of technology, and in
practical applications, have been introduced a multiplicity of
constructions.
2. Discussion of the Prior Art
Current measuring machines, as a rule, are constructed in portal or
a gantry-type constructional mode, and are equipped with a
mechanical probe or sensor head possessing measuring sensors. Other
known measuring and testing machines concern themselves with
non-contacting measurement; for example, through the intermediary
of interferometer systems. Considered by themselves, both methods
of measurement are subject to a series of advantages and also
disadvantages.
Thus, for example, known from the disclosure of German Laid-open
Patent Application 36 16 812 is a coordinate measuring device with
an arrangement for the non-contacting scanning or sensing of the
measured object. Through the intermediary of an interferometric
linear measurement system, the path of displacement of a measuring
mirror for each measuring coordinate, which is fixedly
interconnected with the coordinate table. Hereby, the reference
mirror of the interferometric linear measurement system is rigidly
connected with the scanning system for the measured object such
that, with relatively minor technological expenditures, there can
also be determined even extremely minute displacements of the
imaging objective in comparison with the measured coordinate
direction and enabling the preclusion of any influences caused by
tilting errors.
The specification of German OS No. 36 16 345 discloses an
interferometer system for linear and angular measurement, which is
constituted from a total of two interferometer systems, so as to be
able to simultaneously implement, at a high degree of precision,
linear and angular measurements as well as measurements of
refractive index.
The principle of the interferometric linear measurement is already
known since the year 1890 from the Michelson Interferometer.
However, it is also known that a laser interferometer which is
utilized as a linear measurement system, necessitates a not
inconsiderable additional expenditures in contrast with other; for
instance, mechanical sensor or scanning heads. Through the use of
laser interferometer systems there can be achieved a resolution or
definition of up to 0.01 .mu.m. However, the length of the laser
lightwave is dependent upon the temperature, the pressure and the
humidity in the region which is traversed by the measuring beam.
Any fluctuation in these environmental conditions will act without
inertia or delay on the results of measurement. This signifies
that, on the one hand, laser interferometer-linear measurement
systems afford an extremely good capability for a precise
non-contacting measurement; however, on the other hand, under
unfavorable environmental conditions, are capable of delivering
erroneous measurement results.
In addition to the above-mentioned non-contacting measuring
systems, mechanical sensing or scanning systems are considered to
be within the known general state of the technology. These
mechanical sensing systems for multi-coordinate measuring machines
consist essentially of a spindle on which there is mounted a probe
or sensor head, having styli; provided thereon, and sensor balls or
spheroids on tips of the styli. The mechanical sensing systems are
relatively robust and possess an adequate degree of precision in
their measurement. The deflection of the stylus can be either
translatory or rotational and, upon contacting the workpiece,
generates control signals for the drives. These signals facilitate
the provision of constant-remaining, reproduceable or repeatable
contacting conditions. In the known sensing systems, a further
distinction is made between the measuring and switching
systems.
In the measuring sensing systems, in the position of measurement
the deflection of the probe stylus is determined through systems
for measuring small displacements; whereas in the switching sensor
systems, upon reaching of the defined contacting position or a
define sensor deflection, a switching signal is generated in the
stylus.
Heretofore, prior to the purchase and installation of a coordinate
measuring and testing installation, an expert in this technology
always needed to extremely carefully investigate the conditions in
the utilization and measuring tasks prior to deciding on one or the
other installation; namely, either the non-contacting or mechanical
sensing system. The provision of both variants of the installations
was frequently prohibitive due to space limitations, and
integrating as well as cost reasons.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to develop a
multi-coordinate measuring and testing installation which,
independently of environmental conditions, is employable for
measuring and testing or inspecting tasks which are encounted in
actual practice, and which is simply implementable and at a
relatively low technological expenditure.
Inventively, the foregoing object is attained pursuant to the
invention, in that the scanning or sensing system is constructed as
a multi-sensor system and is constituted from a mechanical sensing
head or probe with at least one stylus and/or a video scanner
and/or a laser scanner which are controlled from a microprocessor
and operate independently of each other, and which are selectively
either individually actuatable by means of software connected
thereto, or can be coupled to each other in a dual or triple
combination. Hereby, in a preferred embodiment of the invention,
for the control or actuation of the entire multi-sensor scanning or
sensing system, there need be installed only a single software and
the laser scanner and video scanner may be located along the same
beam path.
Through this arrangement, within a single unit the measuring and
testing installation avails itself of all known advantages of the
individual scanning or sensing systems. By means of this
multi-coordinate measuring and testing center, in an optimum manner
it is possible to solve all encountered measuring tasks and under
all environmental conditions. The measuring and testing center can
be assembled as a single unit. Just as well, it can also be
integrated into transfer machine installations or processing or
work treatment centers, and as a result thereof introduceable into
the work flow or production line. The coordinate measuring and
testing installation, pursuant to the features of the invention,
unites the non-contactingly operating video scanner, the laser-scan
system and the contacting measuring probe. Thus, there can be
non-contactingly automatically measured suitable surface contours,
as well as expedited pure measuring tasks, whereby the entire
installation optimally fulfills these tasks without the need for
any refitting. The inserted software coordinates the communication
with the video-processor system and the CNC movement control over
the installation. In accordance with the inventive concept, the
inserted different scanning systems can carry out independently of
each other and alternatively the required measuring and testing
tasks. Just as well, they can also be coupled to each other in a
dual or triple combination, and fulfill measuring and testing tasks
in parallel with each other, and finally can be so controlled or
actuated that the required measuring and testing tasks can be
implemented by means of the scanning systems in succession and in
interchangeably different dual and triple combinations.
Pursuant to a particular feature of the invention, there can be
provided two spindles which are movable in the Z-coordinate
direction, of which one spindle supports the mechanical probe with
styli, and the other spindle the video scanner and laser scanner.
In this case, the spindles can be arranged on a common measuring
carriage.
In accordance with a further feature of the invention, there can be
provided a separate measuring carriage can be movable in
synchronism as well as also separately of each other in,
selectively, the same or different coordinate directions.
The least technological expenditure is encountered when the
spindles which are inserted in the Z-direction, together with the
respective scanning systems, are mounted on a common carriage or
other kind of support. Thereby, it is ensured that for certain
measuring and testing tasks there is obtained, for instance, a
reduction with respect to the measuring period. Through the receipt
of the two spindles on separate measuring supports, there are
achieved a series of advantages. The measuring carriages, within
the contexts of the invention, can be movable in synchronism in
either the same or different coordinate directions. They can just
as well be displaced at different times in the same or different
coordinate directions. The large number of possibilities which are
connected with this type of the spindle mounting affords a
measurement and testing under varying conditions and the solution
of even complicated measuring tasks within a short period of time.
Through the combination of the scanning systems in a single machine
installation, there can be further tested the measured results of
the one system by means of the other system.
Pursuant to a further aspect of the invention, the laser scanner
can be utilized in a scanning operation as well as autofocus.
According to a further feature of the invention, the laser scanner,
during scanning operation, continually regulates the movement of
the Z-axis in correlation with the surface contour whereby,
advantageously, the scanning direction is expediently
predeterminable in the X and Y-axis. In order to be able to
continually regulate the contour-detecting measuring axis in
real-time within the effective laser range, and to afford high
scanning speeds at a concurrently high degree of precision in
measurement of about 0.5 .mu.m, and an adjustable measurement
definition of 0.1 .mu.m to 10 .mu.m, the laser scanner can during
scanning operation can follow non-contactingly at a constant
distance the surface contour of a workpiece in the X and
Y-coordinate directions, whereby the laser scanning system is
formed from two interlinked closed control circuits, of which the
first control circuit correlates the transmitting power of the
laser with the reflective characteristic of the workpiece, and in
dependence upon the receiving signal in the receiver controls the
transmitting signal in the transmitter, whereas the second
superposed control circuit controls the continual follow-up of the
carriage or; in essence, the spindle in the Z-direction into the
optimum housing plane.
Hereby, in an advantageous embodiment, the receiver system can be
equipped with differentiating diodes, through which there is
generated a differential signal in conformance with the focused
position of the objective, which by means of an axial amplifier and
a servomotor automatically positions the Z-axis in the focusing
plane. The measuring carriages, or in essence, the spindle with the
laser scanner, can posses a measuring system with a glass measuring
rod of the Z-axis and to convey the current position of height
along the Z-axis to the main computer.
Pursuant to a still further embodiment, the video scanner can pick
up measuring points along the outer contour of the workpiece, which
are determined from a digitalized picture produced by a video
processor for the applicable workpiece segment. The contours of the
workpiece in the X- and Y-coordinates can hereby be determinable
through edge tracing routines in the digitalized picture, and the
measuring points in the Z-direction can be formed with a focusing
apparatus and the camera picture or through a high-precision
laser-focusing system. During the edge tracing routine individual
measuring points are interlinked with each other into a measuring
program. The digitalized picture can be a gray picture as well as a
binary picture.
Finally, the mechanical probe can, selectively, be a switching or a
measuring probe, and the fundamental machine unit can be
constructed in a portal or gantry-like structure with a solid base,
which for the receipt of the workpieces selectively includes a
turntable, and on a traverse receives the measuring carriage or
carriages for the spindles longitudinally displaceably in a
direction of travel which is at right angles to or extends in the
same direction as the gantry, whereby in the measuring carriage or
carriages and the spindles are controllable from a control panel,
and the obtained results of measurement on the picture screen of a
display unit and/or by means of a printer.
BRIEF DESCRIPTION OF THE DRAWINGS
Reference may now be had to the following detailed description of
exemplary embodiments of the invention, taken in conjunction with
the accompanying drawings; which:
FIG. 1 illustrates in a simplified perspective representation a
three-coordinate measuring installation pursuant to the present
invention;
FIG. 2 illustrates a simplified perspective representation of a
three-coordinate measuring installation with two measuring
carriages for the Z-spindles; and
FIG. 3 illustrates a block circuit diagram of a the laser scanning
system with an autofocusing system.
DETAILED DESCRIPTION
The three-coordinate measuring installation 1 pursuant to FIGS. 1
and 2 is a measuring machine, or fundamental machine unit, which is
constructed in the mode of a portal or gantry-like structure with a
stationary portal 2 which is formed from the two side pillars or
supports 3 and the traverse 4. The traverse 4 concurrently
represents the guide track 5 for the cross-carrier 6, the latter of
which supports itself through a support 7 on the second guide track
8. The cross-carrier 6 is displaceable above a measuring table 9
along the two guide tracks 5 and 8 which are arranged in parallel
with each other, until it contacts end stops, which table is
installed between the portal 2 and the guide track 8. The measuring
table 9, pursuant to FIG. 2, is constructed as a measuring
turntable 10.
Reference numeral 11 represents an input or programming
panel.Iadd., or machine control unit, .Iaddend.or a function panel,
through the intermediary of which there can be called up the
individual functions of the measuring installation 1. In order to
convert the commands into corresponding functions, a
computer.Iadd., or microprocessor, .Iaddend.12 is arranged between
the input panel 11 and the measuring installation 1. The results of
measurement are displayable or recordable on a picture screen 13
and/or a printer 14. For this purpose, the picture screen 13 of a
display unit and similarly the printer 14 are connected with the
central computer 12 through the electrical lines 15. The line 16
from the computer 12 is connected with drive elements; for
instance, drive motors for the movement of travel of the
cross-carrier 6 and carriages 17 and 18, and with electronic
devices of the scanning system.
The schematic and simplified representation of the three coordinate
measuring machine or installation is only one of possible types of
construction. Instead of the illustrated embodiment, there can
naturally be expediently employed other known types of
constructions, without deviating from the scope of the invention
and the field of application.
A carriage 17 is arranged on a cross carrier 6, and which is
movable thereon offset by 90.degree. relative to the direction of
travel of the cross-carrier 6. The measuring carriage 17 receives
two spindles 20 and 21 which are displaceable in the Z-direction
19.
In accordance with FIG. 2, two measuring carriages 18 are arranged
on the cross-carrier 6 so as to be displaceable along the
cross-carrier 6. Both measuring carriages 18 each possess,
respectively, a spindle 20 and 21 which are movable in the
Z-direction 19, and which are actuatable independently of each
other. The measuring carriages 18 can be displaceable in
synchronism in either the same or opposite directions. They can be
alternatively movable and carry out different directions of travel
and types of movement.
The spindles or sleeves 20 and 21 are similarly so actuated so as
to be movable in synchronism in the same as well as opposite
directions, or carry out alternative movements.
In the illustrated exemplary embodiment, the spindle 20 presently
mounts the switching sensor head or probe 22, and the spindle 21
mounts the video scanner 23 and the laser scanner 24. Naturally,
the reverse arrangement is also possible with this
construction.
For the determination of the contour of the workpiece surfaces 25,
the three-coordinate measuring installation 1 is equipped with a
laser scanner 24, on the spindle 21, through which there are
automatically measured non-contactingly suitable surface contours.
In contrast with lasers which operate pursuant to the triangulation
method, the laser scanner employed therein follows the surface
contour at a constant distance therefrom. This method possesses the
advantage that the contour-determining measuring axis is
continually regulated in real-time within the effective laser range
and read-off by the central computer 12. Resulting therefrom is a
high scanning speed and a high degree of precision in measurement.
The essential technological advantages of the inserted laser
scanner 24, which is hereinbelow described in more precise detail,
are as follows:
1. Non-contacting determination of measurements which are free of
measuring forces.
2. High scanning speed.
3. Adjustable measuring definition of 0.1 .mu.m to 10 .mu.m.
4. High degree of measuring precision of 0.5 .mu.m.
The laser scanner 24 continually regulates the movement along the
Z-axis 19 in conformance with the surface contour. The scanning
direction along the X-axis and Y-axis by means of the measuring
carriages 17 and 18 and the cross-carrier 6 are expediently
predeterminable through the input panel 11 with computer 12.
Underlying the scanning principle predicated is the so-called
light-intersection method, in which the reflecting surface of the
workpiece 26 is utilized as a reference for focusing. Serving as a
light source 27 is an impulse laser diode 28, whose luminescent
surface is imaged by means of an optical system through the optical
axis 29 of the presently employed lens system 30 onto the workpiece
surface 25. The light beam 31 emanating from the impulse-laser
diode 28 strikes against a mirror 32 which is angled at 45.degree.,
is deflected from there towards a lens 34 and concurrently again
conducted again to a second mirror 33 angled at 45.degree., and
from the latter to the lens 30 over the workpiece surface 25. From
there, the light beam 31 is reflected, and by means of the mirrors
33 and 32 retransmitted to the lens 34. Thus, the workpiece 26
remits a portion of the reflected laser light through the lens 30
and optical system 33, 32, 34 onto a receiver system 36 which is
equipped with the differentiating diodes 35. On the basis of this
type of imaging which is applied in this system, the measuring
point wanders out during the defocusing and generates a
differential signal in the linear amplifier 37, which positions the
Z-axis 19 again in the focusing plane through the intermediary of a
servomotor 38. At 39 the measuring point is displaced towards plus
by the value of .DELTA.F, whereas at 40 there is effected the
displacement towards minus by the value of .DELTA.F. In conformance
with the optical system, these measuring points are reflected to
the differentiating diodes 35, and transmitted further in the
receiver 36 as a signal through the transmitter 28 for correlating
of the measuring carriage 18 in the Z-coordinate 19.
As is further ascertainable from FIG. 3, in addition to laser
scanner 24, the spindle 21 also possesses the video scanner 23
which is essentially constituted from a camera 41 with a
picture-processing device 42. The video scanner 23 operates in a
non-contacting mode along the Z-axis 19 through the lens 30 on the
workpiece surface 25. The determination of the individual measuring
points on a workpiece 26 which is to be considered is effected on
the basis of a gray image of the segment o the measured object
which is digitalized by a video processor 43. The measuring points
are hereby picked up at the outer contour of the workpiece 26. The
applicable contours in the X and Y-directions are determined by
edge finding or tracing routines in the gray image; whereas in the
Z-direction 19, the measuring points are formed with the automatic
focusing apparatus and with the assistance of the camera picture,
or with a high-precision laser-focusing system.
FIG. 3 illustrates in principle, two interdigitating control
circuits 46 and 47. The control circuit 46 through the
interconnection 48 controls the control signal in the transmitting
system 28 in dependence upon the receiving signal. The control
circuit 46 determines the transmitting power of the continuous-wave
laser 24 with respect to the current reflective characteristics of
the workpiece 26.
The control circuit 47 is superimposed on the control circuit 46
and controls the autofocus through the servomotor 38. Hereby, there
is facilitated the continual follow-up of the entire carriage 21 in
the Z-direction is facilitated for a constantly optimum focusing
plane. The position of the carriage 21 in the Z-direction is
maintained through a measuring system 49 with a glass measuring
rod, and transmitted to the main computer 12 through an electrical
line 50.
The servomotor 38 is drivingly interconnected with the spindle 21
for the movement in the z-coordinate direction, as is indicated by
reference numeral 51.
In order to be able to emphasize edges under conditions of poor
contrast, there can be employed filters for the gray image. For the
description of the nominal geometry of the workpieces there are
available the known basic geometric elements, such as point, line,
circle, ellipse, plane, cylinder, sphere and cone.
The switching sensor head or probe 22 has a suitable undefined
sensing deflection and a switch point for the microswitch in the
probe. The scanning is carried out mechanically with the stylus 44
along the surface of the workpiece. Through the scanning contact,
there is actuated microswitch in the probe 22 and an impulse is
transmitted to the computer 12, which represent a measured result.
The stylus 44, in a usual manner supports a sensing ball 45 at its
free end.
It is of considerable importance that the laser scanner 24 and the
video scanner 23 are located or operate along the Z-axis 19 within
the same common beam path 52. Only then is it possible that by
means of both systems; in effect, from the video scanner 23 with
the video camera 41 and a picture processing installation 42, and
from the laser scanner 24 with the impulse-laser diode 28 and the
lens 34, as well as the mirrors 32, 33, there is always determined
the same measuring point on the workpiece 26.
* * * * *