Apparatus and method for optically surveying and/or examining a welding componentry

Apparatus for optically surveying and/or examining a welding componentry, in particular a vehicle axle or instrument panel, includes a measuring space for accommodating a plurality of cameras for taking images of the welding componentry. The images are combined and evaluated in an evaluation unit. Disposed in the measuring space is a support unit for support of the welding componentry. The support unit includes a base plate and at least two vertically adjustable support columns on the base plate. Provided on the free end of each support column is a clamping unit which includes two clamping elements constructed for movement relative to one another for clamping the welding componentry. In addition, the support columns have each a pin which is movable in relation to the clamping unit.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the priority of German Patent Application, Serial No. 10 2005 048 134.5, filed Oct. 6, 2005, pursuant to 35 U.S.C. 119(a)-(d), the content of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus for optically surveying and/or examining a welding componentry, in particular a vehicle axle or instrument panel. In addition, the present invention relates to a method of surveying and examining a welding componentry.

Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.

Heretofore, a welding componentry, e.g. a vehicle axle or an instrument panel, manufactured on a large scale, has been examined, either attributively or through measurement, for determining whether the welding componentry is true to size. Attributive tests involve mechanical tracing gauges. This procedure is time-consuming, inflexible and oftentimes inaccurate and prone to fail. Another approach is described in U.S. Pat. Nos. 5,285,397 or 6,651,351 and involves a random surveying of a welding componentry through use of a coordinate measuring machine. This procedure requires long cycle times and thus is essentially unsuitable for application during production. Components may also be surveyed through scanning of relevant component zones by means of a light section sensor or by means of laser-optical triangulation sensors. The sensors are hereby guided by robots. This in turn incurs high costs and involves also long cycle times.

All afore-mentioned systems assume the task to survey or check complex welding componentries at certain cycle times. To attain at least a required minimum precision, it is important to properly clamp the welding componentry and to precisely configure the optical equipment. A problem encountered to date is hereby to correctly configure the mechanical clamping mechanism so as to ensure a high mechanical stability while still enabling free accessibility for optical sensors to all features being surveyed.

It would therefore be desirable and advantageous to provide an improved apparatus and method for optical surveying and/or examining a welding componentry, to obviate prior art shortcomings and to effect a high mechanical stability when the welding componentry is clamped while providing a sufficient viewing field for the sensors to realize a reliable operation.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, an apparatus for optically surveying and/or examining a welding componentry, in particular a vehicle axle or an instrument panel, includes a measuring space, a plurality of cameras disposed in the measuring space for taking images of the welding componentry, an evaluation unit for evaluating the images, a support unit disposed in the measuring space for support of the welding componentry, with the support unit including a base plate and at least two support columns on the base plate, and a plurality of clamping units respectively provided on a free end of the support columns, with each clamping unit including two clamping elements constructed for movement relative to one another for point or surface clamping the welding componentry, and with at least one of the support columns having a pin movable in relation to its clamping unit.

The present invention resolves prior art problems by providing a flexible and mechanically stable clamping of a welding componentry in the measuring space. As a result, measuring accuracy is enhanced while realizing short measuring times. The respective component or component feature is measured via cameras which take images of the welding componentry from different angles. Using the computer-assisted evaluation unit, the information from each camera can be combined to provide a three-dimensional survey. The photogrammetry uses hereby the images to reconstruct and measure the spatial disposition and three-dimensional shape of the welding componentry. The survey apparatus according to the invention attains a defined clamping of the welding componentry in the measuring space. The provision of plural support columns, e.g. four or more clamping points, affords flexibility to suit a wide variety of different welding componentries, while still achieving a precise and reproducible measurement. For example, a welding componentry can be clamped in four points. Clamping in three points, with the fourth point remaining free in the space, enables a measurement of a “twist”, i.e. rotation, of a welding componentry.

According to another feature of the present invention, at least one of the support columns may be constructed for in and out movement in relation to an image detection range of the cameras. As a result, different clamping variations of the welding componentry can be simulated.

The pins on the support columns or clamping units are used to hold the welding componentry by moving into openings of the welding componentry. Suitably, each pin has two length portions of different diameter. The pins can be constructed with alignment elements for properly positioning the welding componentry. An example of an alignment element involves an element that expands or spreads to thereby adjust the position of the welding componentry. A pin may be equipped with two or three alignment elements to act in one or two independent directions.

At least one of the pins may be configured as “measuring pin” by which the absolute position of a feature of the welding componentry can be measured indirectly via the position of the measuring pin or its support unit in relation to the feature. It is also possible to directly survey or examine a particular feature, e.g. an opening in the welding componentry, by taking a snapshot of this feature.

According to another feature of the present invention, the clamping elements may have recesses to clear a view for the cameras onto a feature disposed between the clamping elements. In this way, accessibility and viewing of the feature to be measured is enhanced for the optical sensors. The clamping elements can thus be configured in such a way as to ensure free optical access to the individual feature being surveyed, even when the welding componentry is clamped.

According to another feature of the present invention, the measuring space can be designed light-proof by providing a suitable enclosure (housing). The enclosure eliminates incident light from outside so that defined light conditions can be created inside the measuring space through use of respective lightings. Defined light conditions promote measuring accuracy and thus represent a prerequisite for the quality of the measurement. Suitably, the measuring space may be pressurized by means of overpressure ventilation. An example of such overpressure ventilation involves the use of a fan with filter to produce a slight overpressure inside the measuring space so that ingress of air contaminants is prevented. This measure also contributes to an enhanced quality of the measuring or examination process.

According to another feature of the present invention, a temperature of the welding componentry may be determined. Measurement of the component temperature enables determination of offset values for the respective measurement so that a measuring result can always be related to a reference temperature or room temperature of 20° C. for example.

According to another aspect of the present invention, a method of surveying a welding componentry includes the step of taking a plurality of images of a feature of a welding componentry for directly surveying the feature of the welding componentry: Subsequently, the images can be evaluated in an evaluation unit.

According to still another aspect of the present invention, a method of surveying a welding componentry includes the steps of determining a position of a pin of a support column for support of a welding componentry in relation to a feature of the welding componentry, and indirectly surveying the feature in response to the position determination of the pin in relation to the feature.

According to yet another aspect of the present invention, a method of examining a welding componentry includes the step of taking an image of a feature of a welding componentry for directly examining the feature of the welding componentry. In this way, a pure survey can be accompanied by a complete inspection of all components of the welding componentry.

The apparatus according to the present invention allows a contactless survey of a welding componentry. The measurement equipment, i.e. cameras with necessary sensors, exposure meter and the like, are fixedly positioned in place. No moving parts of the optical surveying apparatus are required. As a consequence, the apparatus becomes robust and requires little maintenance. Wear is of no concern and trouble sources are minimized. As no moving parts are encountered for the survey, the surveying apparatus operates speedily and the method can be carried out very fast. Many images can be taken simultaneously so that the actual measuring time can be reduced to fractions of seconds. This also has a positive effect on the measuring accuracy because external impacts, e.g. vibrations, have no significant influence on the measuring result. Also possible is a parallel measurement of the component temperature which can be included in the evaluation so that the measuring result can always be related to a room temperature of 20° C. for example.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Turning now to the drawing, and in particular toFIG. 1, there is shown a perspective illustration of an apparatus according to the present invention, for optical surveying and/or examination of a welding componentry, generally designated by reference numeral3, in particular a vehicle axle or instrument panel. X, Y, and Z designate space coordinates inFIG. 1. The apparatus includes a measuring space, also called measuring cell, generally designated by reference numeral1, and a plurality of cameras2disposed in the measuring space1for taking images of the welding componentry3. By way of example, the welding componentry3, shown inFIG. 1, is represented by an axle support, as also shown inFIG. 6.

The measuring space1is demarcated within an enclosure or housing4which is shown only in parts here, without back and front walls as well as ceiling. The enclosure4has sidewalls in the form of a framework32which can be closed by a shutter33so that the measuring space1can be closed off to prevent incident light. The measuring space1is thus constructed light-proof. Although not shown in detail, the measuring space1can be pressurized by means of overpressure ventilation, e.g. fan, to prevent ingress of air contaminants.

A stable base plate5is accommodated in the measuring space1for attachment of five support columns6,7,8,9,10which are provided for clamping the welding componentry3. Support columns7,8,9,10are hereby constructed for vertical adjustment. The support column6has an upper end11formed with two cantilever arms12. Each cantilever arm12has a pin13for engagement in an opening of the welding componentry3. As a result of the provision of five support columns6,7,8,9,10, a wide variety of welding componentries can be surveyed by securing the welding componentry to appropriate ones of the support columns6,7,8,9,10.

FIG. 2shows in greater detail the structure of the height-adjustable support columns7,8,9,10. As the support columns7,8,9,10are of identical construction, except as otherwise noted, the following description is made only in relation to the support column8and is equally applicable to the support columns7,9,10. The support column8has an upper end14which is provided with a clamping unit15having an upper clamping element16and a lower clamping element17which are movable relative to one another by a suitably height-adjustment mechanism, generally designated by reference numeral34. As shown in particular inFIG. 3, the upper clamping element16is swingably mounted to the upper end14for rotation about a horizontal axle18. The lower clamping element17is movable via a support arm19along a vertical guide20. The welding componentry3can be clamped via the clamping elements16,17, e.g. at selected points A, B, C, D, as indicated inFIG. 6. The clamping element16is formed with a recess21and the clamping element17is formed with a recess22so that a viewing range of the cameras2is cleared to be able to focus upon a feature M (cf.FIGS. 4,5) to be surveyed, which is placed between the clamping elements16,17and may involve a hole for example. The support column8further includes a pin23which is movable in relation to the clamping unit15in vertical direction as well as sideways. As shown in particular inFIG. 4, the pin23has two length portions26,27of different diameter so as to define a shoulder that forms a stop28or support surface for the welding componentry3.

As shown inFIG. 7, the pin23of support column8is provided with two alignment elements29,30for alignment of the welding componentry3, with the alignment elements29,30acting in Y-direction so that the welding componentry can be centered by the pin23in Y-direction. Alignment in Z-direction is realized by the stop28of the pin23.

The support columns7and9are provided with pins24,25, respectively. Thus, the welding componentry3can be aligned on the support columns7,8,9,10in zero position. The pin24of the support column7has three alignment elements29,30,31, as shown inFIG. 8, so that the welding componentry3can be aligned in X-direction as well as Y-direction, whereas the alignment in Z-direction is again realized by the stop28of the pins24.

The welding componentry3is imaged by the cameras2from different angles. The information received from each of the cameras2is inputted into a computer-assisted evaluation unit (not shown) for evaluation and 3D-surveying of the welding componentry3.

FIG. 6shows, by way of example, a welding componentry3in the form of an axle support that can be selectively clamped upon four points A, B, C, D of the support columns7,8,9,10for attaining a precise and reproducible measurement of the axle support3. When e.g., measuring a twist of the welding componentry3, the welding componentry3is clamped at the three points A, B, C only, i.e. support columns7,8,9, whereas the fourth point D, support column10, remains free in space. In this case, the support column10and its clamping unit15are suitably moved out of the image detection range of the cameras2. Thus, while the axle support3is clamped in the points A, B, C (three-point support), the position of the axle support in point D can be measured to determine the twist of the axle support3.

A direct survey of a feature M of the welding componentry3is carried out by taking several snapshots of the feature M with subsequent evaluation of the image information in the evaluation device. Also conceivable is an indirect survey of a feature M of the welding componentry3through determination of the position of the pin23,24in relation to the feature M. A direct examination of a feature M of the welding componentry3can be realized through taking a snapshot of the feature M to be controlled.