DE102016006659B4 - Measuring system and method for non-contact measurement of workpieces - Google Patents

Abstract

Measuring system for the contactless measurement of workpieces (14), comprising at least one mounting plate (1), - a laser module (5), - a sensor module (6), - a loading module (2), the loading module (2) at least one vertically movable arranged loading prism (2.1) on which the workpiece (14) can be placed, and wherein the loading module (2) is arranged and equipped in such a way that a movement of the at least one loading prism (2.1) in the vertical direction downward a depositing of the workpiece ( 14) on at least one determination prism (3.1), - a determination module (3), the determination module (3) having the at least one determination prism (3.1) on which the workpiece (14) can be placed for the contactless measurement, and where the at least one determination prism (3.1) determines the position and orientation of the workpiece (14) to be measured in space and a positioning module (4), the individual modules (2-6) each having mounting elements (7) by means of which they vary l can be arranged on the mounting plate (1).

Description

The invention relates to a measuring system and a method for the contactless measurement of workpieces, preferably for the measurement of rotationally symmetrical workpieces.

Workpieces are often measured directly on the machine tool for production control or dimensional control. On the one hand, a low measurement uncertainty is required of the measuring device, on the other hand, it must also be convertible with little effort to measure different workpieces. Furthermore, the measuring device should be sufficiently robust to work reliably and with little operator need under the rough conditions in production. A fast measuring system is also required due to the constantly increasing production speeds.

Tactile, inductive and optical measuring systems are currently used for workpiece measurement. In the case of optical measuring systems, negative influences, such as wear on the probe body or deformation of the workpiece surface due to the test force when probing is avoided from the start. Optical measuring systems can be subdivided into incident light and back light systems, whereby back light systems are often used for a sufficiently low measurement uncertainty and a low susceptibility to external light.

A basic concept of an optical measuring system consists of an LED light source, a high-resolution camera as a sensor and optics for beam guidance. The workpiece as the measuring object is located between the light source and the camera as a sensor. The shadow image recorded by the camera is evaluated with the aid of a computer or software in order to ultimately carry out a target / actual comparison of the shadow image recorded of the workpiece to be measured with a shadow image recorded by a reference workpiece and to determine deviations.

A second concept uses a laser as a light source and a photodiode as a sensor. The light source and the sensor are arranged as a measuring bridge and are moved in the direction of the workpiece by means of an NC axis of a machine tool. If the workpiece enters the light beam, it is interrupted and a switching pulse is triggered via the sensor. The position value of the NC axis is saved. The measuring bridge is moved further until the workpiece has passed and the light beam is released again. Another switching pulse is triggered and the position value of the NC axis is determined. The workpiece dimensions in the area covered by the light beam can be calculated using the two position values. Here, too, the workpiece is located between the light source and the sensor.

These measurement systems have the disadvantage that systematic errors remain undetected, which leads to increased measurement uncertainty.

In another concept, the laser scanner, a laser beam is deflected with the help of a rotating mirror system in order to scan the surface contour of a workpiece. When the laser beam hits, a photodiode triggers a switching pulse, whereby the actual dimensions of the workpiece can be determined via the mirror orientation. As a matter of principle, laser scanners require a drive mechanism to rotate the polygon mirror. The service life and availability of this measuring system is therefore primarily dependent on the reliability of the drive or the rotating mechanism of the mirror.

The use of precise optics for beam guidance generates high costs. Since it cannot be effectively protected in the dirt-intensive production environment, there is a high degree of susceptibility to soiling (e.g. dust, chips, oils, etc.) and damage (e.g. cracks, scratches, etc.), which causes measurement errors and increases measurement uncertainty.

The DE 10 2008 062 458 A1 discloses a device for laser-based measurement of workpieces, assemblies and tools during manufacturing processes in mechanical and plant engineering. An optically measuring, very robust and active sensor system is described. The device for laser-based measurement of workpieces, assemblies and tools has a laser as a light source and an optical sensor in the form of a CCD or CMOS matrix sensor as well as at least one polarization filter in the beam path of the laser radiation, the orientation of the polarization filter corresponding to the orientation of the laser light. After the system has been calibrated, this measuring principle can be used to measure waves. The diameter is primarily of interest. In principle, however, the circularity error can also be measured on a shaft shoulder. Known elements such as prisms or points (mandrels) can be used to determine the position and orientation. However, this is not discussed in detail in this patent specification.

The DE 197 38 977 A1 discloses a measuring device or a measuring device for measuring shafts, in particular for measuring their diameters. The measurement device is described with a holder for a measurement object that is stationary during operation, a transmitter for transmitting a Energy beam transverse to an interesting dimension of the measurement object and a receiver for collecting the energy beam and emitting signals depending on the effects of the measurement object on the energy beam.

From the EP 2 813 812 A1 a device for measuring the inner diameter is known. The device is used in particular to measure the inside diameter of pipes. An optical measuring principle consisting of a light source, a conical mirror and a CCD camera is used. Rollers are used in pairs to determine the pipe. Each pair of rollers has the same effect as a short prism. Since relatively large and heavy objects are to be measured, additional systems for aligning the pipe are explained in the patent. The rollers are adjustable to accommodate different waves and to determine their position.

From the US 7 748 134 B1 a measuring device for measuring cylinders is known. The device described in this patent uses two prisms and an adjustable stop to define a shaft. The circular form error and, if necessary, the runout deviation on a shaft are measured.

The present invention is based on the object of providing a robust, laser-optical measuring system for the contactless measurement of workpieces, which can be permanently in use in the manufacturing plant and can be converted with little effort for the measurement of different workpieces. By means of the measuring system, workpiece lengths and diameters, in particular fits, should be able to be measured quickly and precisely under production conditions, with no separate drive mechanism or NC axes being necessary for the measurement.

The object of the invention is achieved by a measuring system for contactless measurement of workpieces, which has at least the features of claim 1, and by a method according to claim 8. The dependent claims describe advantageous embodiments of the invention.

• • eine Montageplatte,
• • ein Lasermodul,
• • ein Sensormodul,
• • ein Belademodul, wobei das Belademodul zumindest ein vertikal beweglich angeordnetes Beladeprisma aufweist, auf welches das Werkstück auflegbar ist, und wobei das Belademodul derart angeordnet und ausgestattet ist, dass eine Bewegung des zumindest einen Beladeprismas in vertikaler Richtung nach unten ein Ablegen des Werkstücks auf zumindest einem Bestimmprisma bewirkt,
• • ein Bestimmmodul, wobei das Bestimmmodul zumindest ein Bestimmprisma aufweist, auf welches das Werkstück für die berührungslose Vermessung ablegbar ist, und wobei das zumindest eine Bestimmprisma Lage und Orientierung des zu vermessenden Werkstücks im Raum bestimmt sowie
• • ein Positioniermodul,

wobei die einzelnen Module jeweils Montageelemente aufweisen, mittels denen sie variabel auf der Montageplatte anordenbar sind.According to the invention, a measuring system for contactless measurement of workpieces is proposed, comprising at least

• • a mounting plate,
• • a laser module,
• • a sensor module,
• • a loading module, wherein the loading module has at least one vertically movably arranged loading prism on which the workpiece can be placed, and wherein the loading module is arranged and equipped in such a way that a movement of the at least one loading prism in the vertical direction downward a placement of the workpiece on at least causes a determining prism,
• A determination module, wherein the determination module has at least one determination prism on which the workpiece for the contactless measurement can be placed, and wherein the at least one determination prism determines the position and orientation of the workpiece to be measured in space
• • a positioning module,

the individual modules each having mounting elements by means of which they can be arranged variably on the mounting plate.

In the laser module, a laser is arranged in an otherwise closed housing having an opening so that a laser beam generated by the laser can exit the housing through said opening. The opening is dimensioned so that no part of the laser beam is masked or shaded due to the size of the opening. In the sensor module, a sensor is arranged in an otherwise closed housing having an opening in such a way that a laser beam entering the housing through the opening can be detected by the sensor. The opening in the housing is also dimensioned so that no part of the laser beam is masked or shaded. By arranging the laser and the sensor in a housing which is closed except for the opening for the exit or entry of the laser beam, contamination of the laser and the sensor is to be largely prevented.

A determining prism is understood to be a fixedly arranged prism, open against the effective direction of gravity, on which a workpiece can be placed, the position and orientation of the workpiece in space being determined via the design and arrangement of the prism.

In a first embodiment of the invention, the mounting plate is designed as a T-slot plate and the mounting elements have slot nuts by means of which they can be releasably attached to the T-slot plate. In this way, a simple and flexible arrangement of the modules on the T-slot plate according to the grid of the T-slot plate is possible. The modules can be arranged on the T-slot plate in a wide variety of variants, so that the measuring system can be quickly and easily converted to different workpieces and different measuring tasks.

The positioning module preferably comprises a stop element. The positioning module is used to position the workpiece in the direction of its longitudinal axis, which in the case of rotationally symmetrical workpieces is the central axis of the workpiece. For positioning, the workpiece is shifted manually or automatically in the direction of its longitudinal axis until one end of the workpiece or the end of a projection of the workpiece formed transversely to the longitudinal axis rests on the stop element. A workpiece can be positioned reproducibly on the measuring system in the direction of its longitudinal axis. In a further embodiment of the invention, instead of the positioning module, a stop element is arranged or formed on the determination module, preferably on the determination prism. For positioning, the workpiece is shifted manually or automatically in the direction of its longitudinal axis until an end face of the workpiece or the end face of a projection of the workpiece formed transversely to the longitudinal axis rests on the stop element on the determination prism. In a further embodiment of the invention, the stop element comprises an electromagnet for automatic positioning of the workpiece.

In a further embodiment of the invention, the measuring system further comprises a cleaning module and / or a storage module. The cleaning module is preferably designed as a blow-out station. The storage module is used to hold a calibration workpiece, which specifies the reference values to be met for the workpieces to be measured.

In a further embodiment of the invention, the laser module comprises a laser for generating and emitting directed electromagnetic radiation in the range of the visible spectrum between 400 nm to 1200 nm, preferably between 450 nm to 700 nm, and the sensor module at least one optoelectronic sensor for detecting the aforementioned electromagnetic radiation. The sensor is preferably designed as a high-resolution CMOS sensor or CCD sensor.

In a further embodiment of the invention, a polarization filter is arranged in front of the sensor. The polarization filter is used to filter stray light and thus avoid measurement inaccuracies.

The device for vertical movement of the loading prism on the loading module can be designed as a controlled lifting or lowering device or as a shock absorber and / or spring device. A controlled lifting or lowering device can, for example, be operated by compressed air, with a piston that can be acted upon by compressed air being arranged within a cylindrical bore, which can be moved from an upper position in the vertical direction to a lower position in the vertical direction by means of a controlled supply of compressed air against the force of a spring is. A workpiece placed on the loading prism can thus be moved from an upper position in the vertical direction to a downward position in the vertical direction and thereby placed on a determination prism, the loading prism being moved downwards in the vertical direction until the workpiece is free on the determination prism rests and the position and orientation of the workpiece in space is determined by the support of the workpiece on the determination prism.
When the device for vertical movement of the loading prism is designed as a shock absorber and / or spring device, the vertical movement of the loading prism takes place as a result of the weight of a workpiece placed on the loading prism. The loading prism is moved as a result of the weight of a workpiece placed on the loading prism against the force of a shock absorber and / or spring device in the effective direction of gravity, that is, in the vertical direction downwards, until the workpiece comes to rest on the determination prism. The spring force of the spring device must be so small that the workpiece comes to rest on the determination prism with sufficient security that the position and orientation of the workpiece in space are determined by the determination prism and the loading prism has almost no effect with regard to the position and the Orientation of the workpiece goes out when it has come to rest on the determination prism. Accordingly, the function of the spring device consists primarily in resetting the loading prism to the vertical starting position after the workpiece has been removed after the measuring process.

In a further embodiment of the invention, the mounting module comprises a base plate with a means arranged thereon for fastening the mounting module on the mounting plate, means for adjusting the length of the mounting module and a head plate for arranging a laser, a sensor or a determination prism. The mounting module is designed in such a way that the base plate can be firmly arranged by means of the means for fastening the mounting module on the mounting plate in such a way that the top plate is located vertically above the base plate and the means for adjusting the length of the mounting module between the base plate and top plate are trained. By changing the length of the mounting module, the position of the laser, sensor or determination module arranged on the head plate is changed in the vertical direction. The means for fastening the mounting module on the mounting plate correspond in their training with the training of the mounting plate that a quick and detachable arrangement of the mounting module in largely any position on the mounting plate is possible. For this purpose, for example, the mounting plate is expediently designed as a T-slot plate and the means for fastening the mounting module as a slot nut. However, other quickly releasable connecting means are also conceivable. Due to the quickly detachable, largely arbitrary arrangement of a mounting module on the mounting plate and the possibility of changing the length of the mounting module and thus the vertical position of a laser, sensor or determination module attached to the top plate of a mounting module, it is possible to set up the measuring system in a short time adapt to the requirements of a workpiece to be measured. This enables quick changes in the production process. The measuring system can also be used economically for short-term changes to the test geometry or for use in small series, since set-up activities can be carried out by a single person as well as using standardized assemblies and standard parts with simple means and in a short time.

In a further embodiment of the invention, in addition to the means for adjusting the length of the assembly module, further means are arranged for changing the vertical position of a laser, sensor or determination prism arranged on the head plate of the assembly module. The means for adjusting the length of the assembly module can be designed for rough positioning of a laser, sensor or determination prism and the further means for changing the vertical position for vertical fine positioning of a laser, sensor or determination prism.

In a further embodiment of the invention, the measuring system has a control measuring beam for detecting the position of the workpiece on the positioning module. As a result, in addition to the precise determination of the diameter, a length or distance measurement is also possible with very high accuracy, since the longitudinal axial position of the end face of the workpiece resting on the positioning module is recorded by a control measuring beam and the length dimensions to be recorded can thus be corrected. This can be important if the workpiece is for certain reasons, e.g. Burr, is not exactly on the positioning module.

In a further embodiment of the invention, the measuring system comprises a pneumatic control in order to provide compressed air for various functions in the measuring system. The pneumatic control can, for example, provide compressed air for cleaning a workpiece to be measured or for cleaning the opening in the laser module through which the laser beam exits or the opening in the sensor module through which the laser beam enters the sensor module. The prumatic control can also provide compressed air for the controlled lifting or lowering device for vertical movement of the loading prism on the loading module.

In a further embodiment of the invention, means are provided for closing the opening in the housing of the laser module through which the laser beam exits the housing, and / or the opening in the housing of the sensor module through which the laser beam enters the housing and reaches the sensor . The means for closing the opening can be closing elements such as closing covers, flaps or slides, which are designed to be operated by compressed air or operated electromagnetically, but also to be sealing air. The means for closing the opening are controlled in such a way that the opening is only ever released during a measuring process. By closing the openings, the ingress of foreign bodies, such as chips, dust, liquid drops, etc., into the housing and subsequent contamination of the laser or the sensor is to be avoided.

• • Zuführung eines Werkstücks zu dem oder den Belademodul/en und Ablage auf zumindest einem Beladeprisma,
• • Ablage des Werkstücks von dem zumindest einen Beladeprisma auf zumindest ein Bestimmprisma durch vertikale Bewegung des zumindest einen Beladeprismas in Wirkrichtung der Schwerkraft, wobei die Lage und Orientierung des Werkstückes im Raum mittels des zumindest einen Bestimmprismas sowie des Positioniermodules reproduzierbar festgelegt wird,
• • berührungslose Vermessung des Werkstücks mittels eines optischen Verfahrens, wobei gleichzeitig alle zu prüfenden Merkmale des Werkstücks erfasst werden,
• • Übertragung der erfassten Merkmale des zu vermessenden Werkstücks an eine Datenverarbeitungseinrichtung und
• • Vergleich der erfassten Merkmale des Werkstücks mit den Merkmalen eines Referenzwerkstückes mittels der Datenverarbeitungseinrichtung.

The invention also relates to a method for the contactless measurement of workpieces with the measuring system according to the invention, comprising the steps:

• • Feeding a workpiece to the loading module (s) and placing it on at least one loading prism,
• • Depositing the workpiece from the at least one loading prism onto at least one determination prism by vertical movement of the at least one loading prism in the effective direction of gravity, the position and orientation of the workpiece in space being determined in a reproducible manner by means of the at least one determination prism and the positioning module,
• • Contactless measurement of the workpiece using an optical method, whereby all features of the workpiece to be checked are recorded at the same time,
• • Transfer of the recorded features of the workpiece to be measured to a data processing device and
• • Comparison of the recorded features of the workpiece with the features of a reference workpiece by means of the data processing device.

In one embodiment of the invention, the contactless measurement takes place by means of a shadow image method, with the electromagnetic radiation partially darkened by a workpiece edge being detected in the range of the visible spectrum of a laser, preferably a diode laser and the intensity distribution of the shadow image is evaluated using numerical methods. In order to minimize the effort, only relevant areas are preferably recorded. Due to the reproducible positioning of the workpiece, previously defined areas can be recorded and then compared with the calibration workpiece.

In a further embodiment of the invention, the position of the workpiece on the positioning module is detected by means of a control measuring beam. As a result, in addition to precise diameter determination, length or distance measurement is also possible with very high accuracy, since the longitudinal axial position of the end face of the workpiece resting on the positioning device is recorded by a control measuring beam and the length dimensions to be recorded are corrected if the workpiece should be determined Reasons, such as Burr, not exactly on the positioning module.

To achieve the object of the invention, it is also conceivable to combine the above-described embodiments with one another in an expedient manner.

• 1: schematisch eine erste Ausführungsvariante des Messsystems, in
• 2: das Messsystem gemäß 1 mit einem zu vermessenden Werkstück, in
• 3: eine Seitenansicht des auf ein Messsystem gemäß 1 aufgelegten und positionierten Werkstückes, in
• 4: eine freigestellte Seitenansicht des auf ein Messsystem gemäß 1 aufgelegten und positionierten Werkstückes, in 5: schematisch eine andere Ausführungsvariante des Messsystems mit einem zu vermessenden Werkstück, in
• 6: eine Seitenansicht des auf ein Messsystem gemäß 5 aufgelegten und positionierten Werkstückes, in
• 7: eine freigestellte Seitenansicht des auf ein Messsystem gemäß 5 aufgelegten und positionierten Werkstückes, in 8: schematisch ein Belademodul, in
• 9a-c: schematisch die Ablage eines Werkstückes auf einem Bestimmmodul, in
• 10a-c: schematisch den Verschluss einer Öffnung mittels eines druckluftbetrieben Verschlussschiebers und in
• 11a-d: eine schematische Darstellung der gleichzeitig erfassbaren, zu prüfenden Merkmale am Beispiel verschiedener Werkstücke.

The invention will be explained in more detail below on the basis of a few exemplary embodiments and associated figures. The exemplary embodiments are intended to describe the invention without restricting it. The associated figures show in

• 1 : schematically a first variant of the measuring system, in
• 2 : the measuring system according to 1 with a workpiece to be measured, in
• 3 : a side view of the on a measuring system according to 1 placed and positioned workpiece, in
• 4th : an isolated side view of the on a measuring system according to 1 placed and positioned workpiece, in 5 : schematically another variant of the measuring system with a workpiece to be measured, in
• 6th : a side view of the on a measuring system according to 5 placed and positioned workpiece, in
• 7th : an isolated side view of the on a measuring system according to 5 placed and positioned workpiece, in 8th : schematically a loading module, in
• 9a-c : schematically the deposition of a workpiece on a determination module, in
• 10a-c : schematically the closure of an opening by means of a compressed air operated locking slide and in
• 11a-d : A schematic representation of the features to be tested that can be recorded simultaneously using the example of different workpieces.

1 shows a first embodiment of the measuring system for measuring rotationally symmetrical workpieces, in particular shafts, in a lateral perspective view. The measuring system comprises a mounting plate designed as a T-slot plate 1 , on which two loading modules 2 , a determination module 3 , a positioning module 4th , four laser modules 5 and four sensor modules 6th are arranged. The mounting plate 1 and the modules 2 - 6 form a kit such that the modules 2 - 6 for measuring different ratation symmetrical workpieces according to the measuring task on the mounting plate 1 positioned can be arranged. Every module 2 - 6 has a mounting element 7th on. Every assembly element 7th has a footplate 7.1 on. On every footplate 7.1 is at least one slot nut 8th (please refer 8th ) arranged so that the mounting element 7th by bracing the footplate 7.1 against the mounting plate designed as a T-slot plate 1 on the mounting plate 1 can be firmly arranged. Here is the position of the arrangement of the mounting element 7th on the mounting plate 1 freely selectable according to the arrangement of the T-slots. The assembly elements 7th and with it the modules 2 - 6 can thus on the mounting plate 1 largely arbitrarily positioned according to the position of the T-slots. The footplate 7.1 is designed and the sliding blocks 8th are arranged so that when the mounting plate is aligned horizontally 1 the mounting elements arranged on the mounting plate 7th aligned vertically. The assembly elements 7th the loading modules 2 , the laser modules 5 and the sensor modules 6th include means of changing their length 7.3 . The assembly elements 7th of the laser modules 5 and the sensor modules 6th also include a headstock 7.2 on which a device for fine adjustment 9 the vertical position of one on the fine adjustment device 9 arranged laser 10 or sensors 11 is arranged. Any laser 10 and every sensor 11 is surrounded by a housing, each with an opening 12 for the exit or for the inlet of the laser beam. On the positioning module 4th is an adjustable stop element 13th arranged. Every loading module 2 includes a loading prism 2.1 , which is movable in the vertical direction on its mounting element 7th is arranged that at one, by one on the loading prism 2.1 placed first workpiece 14.1 for which that in the 1 - 4th measuring system shown is set up (see 2 ), the weight acting on the loading prism 2.1 is vertically movable in the direction of the effect of the weight. Each Determination module 3 includes a determining prism 3.1 . The loading modules 2 and the determination module 3 are like this on the mounting plate 1 arranged that the loading prisms 2.1 and the determining prism 3.1 are largely aligned. They are in the rest position, ie without a workpiece to be measured 14th , in the vertical direction the loading prisms 2.1 arranged higher than the determination prism 3.1 . Parallel to the alignment line of the prisms 2.1 and 3.1 are the laser modules 5 and the sensor modules 6th arranged, with one laser module each 5 and one sensor module each 6th are arranged corresponding to one another and aligned vertically so that one of the laser module 5 emitted laser beam from the corresponding sensor module 6th can be received.

2 shows the described measuring system according to 1 with one on the determining prism 3.1 overlying workpiece 14.1 . The 3 and 4th show the measuring system with one on the determining prism 3.1 overlying workpiece 14.1 each in side view, where 4th was released to the extent that only the mounting plate 1 , the loading modules 2 , the determination module 3 , the positioning module 4th and the workpiece 14.1 are shown. The following explanation refers to the 2 - 4th . For measuring the workpiece 14.1 this is done manually or by a suitable automatic workpiece transport system on the loading prisms 2.1 hung up. Depending on the training of the loading modules 2 the loading prisms lower 2.1 due to the weight of the workpiece 14.1 in the direction of the effect of the weight force or are controlled in the vertical direction in the effective direction of the weight force of the workpiece 14.1 moves until the workpiece 14.1 on the determining prism 3.1 rests. The loading prisms 2.1 are moved so far in the vertical direction that the workpiece 14.1 free on the determination prism 3.1 rests. The workpiece 14.1 is then manually or automatically along its longitudinal axis 15th up to the stop against the stop element 13th on the positioning module 4th emotional. After that is the workpiece 14.1 its position and orientation in space is clearly and reproducibly determined and can be measured.

5 shows a second embodiment of the measuring system for measuring another second rotationally symmetrical workpiece 14.2 . In contrast to that in the 1 - 4th The measurement system shown in 5 The measuring system shown only has a loading module 2 and two determination modules 3 . Instead of the positioning module 4th des in the 1 - 4th measuring system shown in 5 measuring system shown on the in 5 shown front determination prism 3.1 of the front control module 3 a stop element 13th arranged. Depending on the measurement task, the measurement system includes three laser modules 5 and three corresponding sensor modules 6th . 5 also shows a cleaning module 16 and a storage module 17th . The cleaning module is designed as a blow-off station in which a workpiece 14th Before the measurement can be blown off with compressed air and thus cleaned of adhering dirt, chips and coolant. The storage module 17th is used to store a reference workpiece with which the measuring system is measured. The measured features of the reference workpiece are stored in a data processing device.

The 6th and 7th show the measuring system with one on the two determination prisms 3.1 overlying workpiece 14.2 each in side view, where 7th was released to the extent that only the mounting plate 1 , the loading module 2 , the determination modules 3 and the workpiece 14.2 are shown. The workpiece to be measured 14.2 is on the loading prism 2.1 placed, which is then moved vertically in the effective direction of gravity until the workpiece 14.2 on the two determination prisms 3.1 comes to rest and rests freely, ie its position and orientation no longer through the loading prism 2.1 being affected. The following is the workpiece 14.2 in the direction of its longitudinal axis 15th moved until a predetermined transverse to the longitudinal axis 15th workpiece surface lying on the in 7th determination prism on the left 3.1 attached stop element 13th is applied. The workpiece 14.2 is then through the two determining prisms 3.1 and the in 7th left determination prism 3.1 attached stop 13th its position and orientation in space is clearly and reproducibly determined and can be measured.

8th shows a loading module 2 with a vertically movable loading prism 2.1 , which after placing a workpiece 14th by the weight of the workpiece 14th against the force of a shock absorber-spring combination 18th , 19th is moved in the effective direction of gravity. This in 8th shown loading module 2 works independently and does not require any additional pneumatic, hydraulic or electrical drive or control to function. The loading prism 2.1 is on two in linear ball bearings 20th guided straight pins 21st arranged, which a smooth vertical mobility of the loading prism 2.1 cause. Proper functioning of the loading module 2 is bound to a vertical arrangement on a substantially horizontally aligned mounting plate. However, this is the case for all practically relevant applications of the measuring system.
After placing a workpiece 14th on the loading prism 2.1 this is due to the weight of the workpiece 14th essentially against the force of the shock absorber 18th moved in the vertical direction in the effective direction of gravity. The vertical movement of the loading prism 2.1 is through those in roller ball bearings 20th mounted straight pins 21st guided. The vertical movement of the loading prism 2.1 with the workpiece resting on it 14th continues until the workpiece 14th to rest on a determination prism 3.1 or more determination prisms 3 comes or on the determination prism or prisms 3.1 was filed. After the workpiece has been deposited 14th on a determining prism 3.1 or several determination prisms 3.1 goes from the shock absorber 18th almost no force acting on the workpiece 14th out. The force of the spring 19th on the workpiece 14th is so small that that of the determining prism 3.1 effected position and orientation of the workpiece 14th is not affected. The function of the spring 19th consists primarily in resetting the loading prism 2.1 in the initial state after the workpiece 14th was removed after the measurement process.

9 illustrated with the three 9a , 9b and 9c the process of placing a on a loading prism 2.1 placed workpiece 14th on a determining prism 3.1 (shown in dashed lines). The loading module 2 includes in 9 The training shown is a controlled, compressed air-operated lifting or lowering device for vertical movement of the loading prism 2.1 . The lifting or lowering device comprises a cylinder 22nd in which a piston 23 can be charged with compressed air against the spring force of a spring 24 is arranged longitudinally axially, in the present case vertically, movable. An arrow 25th illustrates the longitudinal axial direction of the movability of the piston 23 . There is a piston rod on the piston 26th placed by the top end wall of the cylinder 22nd protrudes. At the end of the piston rod protruding through the front wall 26th is the loading prism 2.1 arranged. The interior of the cylinder 22nd between the piston 23 and the upper end wall of the cylinder through which the piston rod 26th is passed through is designed as a pressure chamber. In the cylinder wall below the piston 23 is a pressure equalization opening 27 brought in. The piston 23 is by a straight pin 28 secured against rotation. Via controlled valves 29 the pressure chamber can be pressurized with compressed air. 9a shows the piston 23 in its upper end position, in which it is due to the force of the spring 24 was moved while the pressure chamber is not pressurized with compressed air. That on the piston rod 26th arranged loading prism 2.1 protrudes in the vertical direction over the determination prism 3.1 out. One on the loading prism 2.1 placed workpiece 14th lies only on the loading prism 2.1 on. For lowering the loading prism 2.1 and for placing the workpiece 14th on the determining prism 3.1 is controlled via the valves 29 compressed air is applied to the pressure chamber. The piston 23 is in the vertical direction against the force of the spring 24 pressed from its upper end position towards its lower end position. The loading prism is thereby 2.1 with the workpiece resting on it 14th in the direction of the arrow 25th in 9b , so down, moved. At the in 9b position of the piston shown 23 or the loading prism 2.1 becomes the workpiece 14th on the determining prism 2.1 hung up. When compressed air is applied to the pressure space, the piston becomes 23 and thus also the loading prism 2.1 moved further towards its lower end position. The workpiece 14th is now exposed on the determination prism 3.1 on. The position and orientation of the workpiece 14th in space becomes through the determining prism 3.1 certainly. 9c illustrates this lower end position of the piston 23 or the loading prism 2.1 .

10 shows a closure of an opening that functions analogously to the controlled, compressed air-operated lifting or lowering device 12 in a housing of a laser or sensor module 5 , 6th , with either a laser in the housing 10 or a sensor 11 is arranged and through the opening 12 either one from the laser 10 generated laser beam 30th exits or a laser beam, possibly partially darkened by a workpiece edge, enters and hits the sensor arranged in the housing 11 hits. A repetition of the description of the structure and the function of the lifting and lowering device is dispensed with. In contrast to that according to 9 device described in 10 device shown the piston rod 26th designed as a closure element. 10a shows the piston 23 in its upper end position. The closure element covers the opening 12 Completely. The opening 12 is locked and the interior of the housing, in which there is a laser 10 or a sensor 11 is protected against the penetration of foreign bodies such as chips, dust and drops of liquid. 10b illustrates releasing the opening 12 . This is done via the controlled valve 29 compressed air is applied to the pressure chamber and so is the piston 23 with the piston rod designed as a closure element 26th downwards, ie in the direction of their lower end position. The arrow 25th in 10b illustrates this movement. The closure element gives the opening 12 free and the laser radiation 30th can through the opening 12 emerge from the housing or penetrate into the housing. In the in 10c position of the piston shown 23 and thus the closure element can be measured for the workpiece.

The outer contour of a workpiece 14th , primarily diameter and length, is measured contactlessly in the shadow image process with high precision by the radiation of a laser, which is partially darkened by a workpiece edge 10 , for example a diode laser, by means of a sensor 11 recorded and the intensity distribution of the silhouette using numerical methods is evaluated. The measurement result results from a target / actual comparison with the value of a previously measured value of a reference edge of a reference workpiece which is stored in the data processing unit. As a sensor 11 Optoelectronic sensors in the form of high-resolution gray-scale CMOS sensors are used. Before every sensor 11 A polarization filter can be arranged to filter out stray light. No beam expansion through lens optics is required for the measurement. The underlying measuring principle is from the DE 10 2008 062 458 A1 known. The arrangement of the laser is new 10 , the sensor 11 and, if necessary, the polarization filter behind closable air barrier and the waiver of color filters and a second polarization filter in the beam path of the laser. Furthermore, the matrix of the CMOS sensor is not opposite to the direction of the laser radiation 30th inclined.

After the workpiece has been deposited 14th on the determining prism 3.1 or the determining prisms 3.1 and the positioning in the direction of its longitudinal axis 15th the workpiece is clearly determined in its position and orientation in space and can be measured. All features to be checked can be recorded at the same time, as in 11a - d shown as an example. Relevant dimensions of the outer contour of the workpiece 14th can be done directly using a silhouette 31 can be checked without the laser beam 30th over the contour of the workpiece 14th must be performed. 11a illustrates the determination of a workpiece diameter D. , 11b the determination of a length dimension L. of the workpiece. This is made possible by calibrating the measuring system and the fact that workpieces are inserted one after the other 14th are in a predetermined, identical position and orientation in space and only the relevant areas of the workpiece contour are measured. For this purpose it is particularly possible in one and the same shadow image 31 several areas to be evaluated 32 to record both diameters and lengths at the same time ( 11c ). There is also the possibility of measuring a groove ( 11d ) with minimum width B <2mm. By arranging several corresponding laser and sensor modules 5 , 6th A wide variety of measurement scenarios can be implemented with the measurement system, depending on the workpiece contour and measurement task. This is the main focus of the measuring system. Without the possibility of different arrangements of different modules from the described possibility 2 - 6 The resulting flexibility of the measuring system would not allow simultaneous precise measurement of several workpiece features and changing workpiece geometries with one and the same measuring system, or only to a very limited extent.
Due to the described module combinability of the measuring system, in addition to precise diameter determination ( 11a) also the length or distance measurement ( 11 b) possible with very high accuracy because the position of the workpiece is in the direction of its longitudinal axis 15th is precisely defined.

A typical application with high accuracy requirements for distance measurement is the determination of the longitudinal axial position of a groove ( 11d ), which, for example, receives a retaining ring for the longitudinal axial fixing of a bearing on a shaft. The groove position is subject to very small tolerances, as the bearing must sit clearly and without play on the shaft. Such measurement tasks, particularly with regard to the measurement accuracy to be achieved, have so far only been realizable with great effort or with measurement devices specially provided for this application.

The measuring system can be converted and used in many ways, with the same modules always 2 - 6 can be used to solve a wide variety of measurement tasks. The simple and clear structure ensures that the measuring system can be converted for the next measuring task with little effort after completion of a measuring task. After the measuring system has been set up for a measuring task and a reference measurement has been carried out with a reference workpiece, workpieces are measured in quick succession 14th as required in series production, possible.

The measuring system is suitable for statistical process control, preferably via EDP, in which, following production, certain features and dimensions of a workpiece according to a test plan 14th be measured. The measurement results can be taken over, evaluated and documented automatically or manually in a data processing device installed at the measuring station. If there is a trend with regard to the measured values, it is possible to intervene in the production process before the dimensions move outside the tolerance limits. This can be done by replacing worn tools or regulating the machine tool. In the latter case, a control signal is formed from the dimensional deviation (target / actual value deviation) in order to change the setting of the machine tool with regard to a smaller dimensional deviation.

There is a pneumatic control to provide compressed air for various functions in the measuring system and at least one electronic control to operate various modules, such as the laser and sensor modules 5 , 6th , and to provide control signals for the pneumatic control.

The transmission of control signals between the data processing device and the machine control can take place wirelessly. A wireless signal transmission path can be both a radio signal path and a light signal path.

The measured workpiece 14th is manually or automatically and clocked by a workpiece transport system from the measuring system, ie from its support on the determination prism 3.1 or the determining prisms 3.1 , removed and transported on.

List of reference symbols

1 -

Mounting plate

2 -

Loading module

2.1 -

Loading prism

3 -

Determination module

3.1 -

Determination prism

4 -

Positioning module

5 -

Laser module

6 -

Sensor module

7 -

Mounting element

7.1 -

Footplate

7.2 -

Headstock

7.3 -

Means of changing the length

8th -

Sliding block

9 -

Device for fine adjustment

10 -

laser

11 -

sensor

12 -

opening

13 -

Stop element

14 -

workpiece

14.1 -

first workpiece

14.2 -

second workpiece

15 -

Longitudinal axis

16 -

Cleaning module

17 -

Storage module

18 -

Shock absorbers

19 -

feather

20 -

Roller ball bearings

21 -

Straight pins

22 -

cylinder

23 -

piston

24 -

feather

25 -

Arrow to illustrate a longitudinal axial mobility

26 -

Piston rod

27 -

Pressure compensation opening

28 -

Straight pin

29 -

Valve

30 -

laser beam

31 -

Silhouette

32 -

area to be evaluated

B -

width

D -

diameter

L -

length

Claims (9)

Measuring system for the contactless measurement of workpieces (14), comprising at least - a mounting plate (1), - a laser module (5), - a sensor module (6), - A loading module (2), wherein the loading module (2) has at least one vertically movably arranged loading prism (2.1) on which the workpiece (14) can be placed, and wherein the loading module (2) is arranged and equipped in such a way that a movement of the at least one loading prism (2.1) causes the workpiece (14) to be deposited on at least one determination prism (3.1) in the vertical direction downwards, - A determination module (3), wherein the determination module (3) has the at least one determination prism (3.1) on which the workpiece (14) can be placed for the contactless measurement, and the at least one determination prism (3.1) position and orientation of the to measuring workpiece (14) determined in space as well - A positioning module (4), the individual modules (2-6) each having mounting elements (7) by means of which they can be arranged variably on the mounting plate (1). Measuring system according to Claim 1 , characterized in that the mounting plate (1) is designed as a T-slot plate and the mounting elements (7) have slot nuts (8) for a quick and detachable arrangement of the modules (2-6) on the T-slot plate. Measuring system according to Claim 1 or 2 , further comprising a cleaning module (16) and / or a storage module (17). Measuring system according to one of the Claims 1 to 3 , characterized in that the laser module (5) comprises a laser (10) for generating and emitting directed electromagnetic radiation (30) in the range of the visible spectrum between 400 nm to 1200 nm or between 450 nm to 700 nm and the sensor module (6) comprises at least one optoelectronic sensor (11 ) for detecting the aforementioned electromagnetic radiation (30), the sensor (11) being designed as a high-resolution CMOS sensor or CCD sensor. Measuring system according to Claim 4 , characterized in that a polarization filter is arranged in front of the sensor (11). Measuring system according to one of the Claims 1 to 5 , characterized in that the loading module (2) has a device for vertical movement of the loading prism (2.1), which is designed as a controlled lifting or lowering device or as a shock absorber (18) and / or spring device (19). Measuring system according to one of the Claims 1 to 6th , further comprising a closure (26) in the area of the laser module (5) and / or the sensor module (6) for closing an opening (12) through which the electromagnetic radiation (30) leaves the laser module (5), and / or a Opening (12) through which the electromagnetic radiation (30) penetrates into the sensor module (6). Method for the contactless measurement of workpieces (14) with a measuring system according to one of the Claims 1 to 7th comprising the steps: - feeding a workpiece (14) to the loading module (s) (2) and placing it on at least one loading prism (2.1), - placing the workpiece (14) from the at least one loading prism (2.1) onto at least one Determination prism (3.1) by vertical movement of the at least one loading prism (2.1) in the effective direction of gravity, the position and orientation of the workpiece (14) in space being determined reproducibly by means of the at least one determination prism (3.1) and the positioning module (4), Contactless measurement of the workpiece (14) by means of an optical method, whereby all features of the workpiece (14) to be checked are recorded at the same time, - transmission of the recorded features of the workpiece (14) to be measured to a data processing device and - comparison of the recorded features of the workpiece ( 14) with the features of a reference workpiece by means of the data processing device. Procedure according to Claim 8 , characterized in that the contactless measurement is carried out by means of a shadow image method, the electromagnetic radiation (30) partially darkened by a workpiece edge being recorded in the range of the visible spectrum of a laser (10) or a diode laser and the intensity distribution of the shadow image (31) being recorded using numerical methods is evaluated.

Images