HK1213981B - Test device and method for testing the interior walls of a hollow body - Google Patents

Description

The present invention relates to a test apparatus for testing the interior walls of a hollow body, in particular a cylinder bore in an engine block, as stated in claim 1, and to a method for testing the interior walls of a hollow body as stated in claim 11.

In the manufacture of engine blocks, but also of various other products, the wall properties of a cavity are of great importance. These can be coated with a special coating. For example, the running surfaces of cylinder boreholes in an engine block of an internal combustion engine or of working cylinders are often coated, for example by wire or powder-based thermal injection.

In general, the scope of the invention is not limited to engine components but includes all tasks involving the examination of the inner walls of a workpiece.

Known test devices for testing the interior walls of a hollow body and known methods for testing the interior walls of a hollow body require a high level of manual work. The performance of a measurement appropriate to the object under study and the evaluation of the measurement require relatively high knowledge requirements on the user and involve a high time consumption.

The standard method of visual inspection of the interior walls, whereby a person inspects the interior walls with the naked eye, is not always possible, but a still more disturbing low roughness cannot be detected in this way.

DE 10 2004 043 209 A1 describes a method and device for measuring the interior wall of a cavity, preferably a borehole wall, using a CCD camera which takes a ring-shaped measuring beam reflected from the surface of the interior wall and thus misses the profile of the cavity.

DE 198 13 134 A1 describes a large container inspection procedure which involves taking images of the interior walls of the large container with a camera for inspection purposes.

According to DE 197 46 662 A1, another measuring device is also known, which is also intended for measuring a borehole: a beam of light is used to detect the inner contour of the borehole by means of a light-cutting method.

For the purpose of testing a cylinder bore in an engine block, in particular in a marine engine, WO 99/15853 provides for a measuring device which can be lowered into the cylinder bore and which, after being positioned, makes a large number of individual measurements on the cylinder wall.

For the measurement of a small cavity, EP 1 797 813 A1 provides for an optical measuring device with confocal distance sensors, which uses point light sources to measure the interior wall of the cavity at selected points.

The present invention may be regarded as a test device and a method for testing the internal walls of a hollow body which can reliably and in a short time, in particular stepwise to a manufacturing process, detect surface properties or defects on the internal walls.

This task is solved by the test apparatus with the characteristics of claim 1 and by the procedure with the characteristics of claim 11.

Beneficial variants of the method and test apparatus of the invention are the subject of the dependent claims and are further explained in the following description, in particular in relation to the figures.

A test apparatus according to the invention for testing the interior walls of a hollow body, in particular a cylinder bore in an engine block, shall comprise at least: Holding device for holding the hollow body,a rod-shaped camera device designed to capture an image along a longitudinal axis of the rod-shaped camera device,a switch device for inserting and exiting the camera device into the hollow body,a lighting device for illuminating the interior walls of the hollow body,electronic control and evaluation devices designed to capture a circular image around the longitudinal axis of the rod-shaped camera device,direct the camera device and determine surface characteristics of the interior walls from image data taken by the camera device,and a diameter measuring device for determining the interior of a headset, where the measuring device has a light source to emit a beam of light on the interior walls of the cavity and optical measuring devices to detect light coming from the interior walls of the cavity, and where the control and evaluation devices are designed to determine the internal diameter of the cavity from measurement information from the diameter measuring device.

The camera and the diametric measuring device may simultaneously or successively examine either the same cavity or two different cavities of the body, so that the interior walls of a cavity into which the camera is inserted and the interior walls of the cavity measured by the diametric measuring device may be either identical or different, in the latter case both cavities may be examined successively by both the camera and the diametric measuring device.

Surface characteristics may include, for example, roughness, the presence of scratches, splashes, the uniformity of a coating, the colour and/or brightness of the interior walls.

The camera may be designed to capture a circular image by taking a single image; alternatively or additionally, the control and evaluation devices may be designed to control the capture of several images in succession and then combine them to form a circular image; the adjustment device may rotate the camera between the different images along the longitudinal axis.

In a method according to the invention for testing the interior walls of a cavity, the test apparatus according to the invention is used to test the interior walls with the rod-shaped camera device, taking at least one image while the camera device is driven into the cavity by the adjusting device.

The essential advantage of the invention is that a workpiece can be controlled with high precision and reliability without any action by a user.

A first key idea is to use a hollow body stop and a camera adjustment device to allow the camera to move towards the hollow body to be examined. This allows the precise and reproducible positioning of the camera and the diametric measuring device, which are important for measuring accuracy. In order to examine the interior walls in a short time and without any unnecessary movements, the camera can be able to capture a circular image. A circular image can represent a 360° image, which thus covers the entire area to be measured in the perimeter direction of the interior walls.

The lighting device may comprise a lighting device and necessarily comprises a lighting device for a driving beam. As a lighting device, its optical beam may be placed next to a receiving optical of the camera. A main beam direction of the lighting device may be essentially parallel to a main receiving direction of the camera, for example at an angle of less than 20°.

A passing beam lighting device, on the other hand, is so arranged that the beam directions of the passing beam lighting device in which it illuminates interior walls in operation are perpendicular to the receiving directions from which the camera receives light from the illuminated interior walls. This allows small irregularities or other irregularities of the interior walls to be easily detected. For example, the beam directions of the passing beam lighting device are not essentially parallel to the receiving directions of the camera device. Rather, a passing beam lighting device is used, the beam directions of which are perpendicular to the receiving directions from which the camera receives light from the illuminated interior walls. This results in a shadow being cast to enhance the transformation of the light when the height variations are passed through.

The direction of radiation may be understood as the whole angular range in which light is emitted from a particular point of the dipped-beam lighting device or alternatively as the angular range of light emission in which the emitted light actually encounters interior curvatures during measurement.

The angle between the direction of illumination of a particular point of the interior walls and the direction of reception of light from the same point measured by the camera is close to 90°.

The angle between the direction of the beam of the passing beam and the direction of the reception of the camera shall be between 45° and 135°, in particular between 60° and 120°, preferably between 75° and 105°.

Furthermore, for a large shadow casting, the direction of illumination relative to the longitudinal direction of the cavity being examined is decisive. These directions may preferably be almost parallel to each other. For example, it may be provided that light emitted from the strip lighting device on the interior walls will strike them at an angle of less than 25°, preferably less than 15° or 10°.

The term "interior walls" may be understood as the inner surfaces of a cavity of a hollow body to be tested, which may be open on both sides of the face or only on one side.

The hollow body can be any workpiece with at least one hole or break as a cavity, for example a motor block in which several cylinder holes have been produced as cavities to be tested.

The holder may be designed in such a way that a hollow body held in a position relative to other components of the test device, such as the camera, is in a defined position. Alternatively, the holder may also be designed in such a way that a hollow body can be in different positions on the holder, as is the case, for example, with a conveyor belt as a holder.The camera body itself can also be used as a means of positioning or as part of it. The rod shape of the camera body makes it easy to insert it into various shaped cavities. A rod shape can be considered in particular a shape whose length is significantly larger than its cross-sectional dimensions, for example at least 4 times or at least 6 times larger.which is outside the rod-shaped area.

The barrel camera shall have a light entry area through which light can enter the camera to take an image of the interior walls, in particular at its lower end, i.e. at the end with which it is first introduced into the cavity.

The camera assembly is operated by the adjustment device relative to the hollow body. This may be provided that the camera assembly is also operated relative to the floodlight assembly. This simplifies the design of the floodlight assembly, particularly with regard to size restrictions, and facilitates precise movement of the camera assembly. Alternatively, the floodlight assembly may be rigidly coupled to the camera assembly and thus be adjusted together with it. This offers, inter alia, the advantage of achieving uniform illumination of the area taken up by the camera assembly at different camera assembly positions.

A camera system adjustment by the adjustment device can generally be understood as at least adjusting its field of view, i.e. its range of vision. For example, an external mirror can be moved while other components of the camera system remain fixed, such as a camera chip. However, for increased safety in a harsh manufacturing environment, it may be preferable for the optical components to be incorporated into a rod-shaped housing that can be moved by the adjustment device. The rod-shaped housing may contain an overpressure and may provide means for air dispersion of front optics through which light can be introduced into or expelled from the housing. This improves dust protection.

The camera may be designed to capture one round image at a time, or alternatively, the camera may be rotated by the adjustment device to capture several images in succession, which are then combined by the electronic control and evaluation devices into a single round image.

The strip lighting device may be formed as a ring light, which is arranged centrally to the rod camera device. The ring surface is perpendicular to the longitudinal direction of the rod camera device. This improves the homogeneity of the lighting. For a design as a ring light, the strip lighting device may include several light sources, for example at least 4 or 8 light sources arranged along a ring shape.

The passing beam lighting device shall be so arranged as to be outside the body of the cavity when the camera is inserted into the body of the cavity. When the camera is inserted, the passing beam lighting device may be moved or rested. By positioning it outside the body of the cavity, illumination of the interior walls can be achieved from a direction approximately parallel to the longitudinal direction of the cavity without the risk of a collision with the body of the cavity.

The control and evaluation devices may also be designed to determine a height profile or interior wall roughness from the measurement data of the measuring device.

The diameter measuring device may consist of at least one triangulation sensor or may include several triangulation sensors, such as at least four, which may be arranged in a ring around the rod-shaped camera device.

For example, a triangulation sensor may have separate transmitting and receiving optics, whereby light coming from a region illuminated by the transmitting optics is directed through the receiving optics to different light-sensitive sensors or sensor regions depending on the distance of the region from the triangulation sensor.

The triangulation sensor may be so oriented as to examine an area of the interior walls which is also examined by the camera.

The camera and the diameters are often tested in several cavities, so that the camera and the diameters can be tested simultaneously in different cavities, reducing the need for a compact design and allowing the test to be carried out in a short time.

If the diametric measuring device is so arranged relative to the camera device that both can be driven into different cavities at the same time, the diametric measuring device may have associated drives.

Alternatively, the diametric measuring device and the camera may be arranged to examine the same cavity simultaneously.

It may be preferable to have the diametric device rigidly coupled to the camera device, so that both are positioned at height relative to the hollow body by means of the adjustment device and can check different height ranges of the hollow body in succession.

The device for measuring diameter is preferably formed as a confocal sensor, which has a common optical element for sending light from the light source to the inner walls and for directing light from the inner walls to the optical measuring instrument.

The measuring device may comprise a light-wave conductor which conducts the emitted light and/or the light to be detected, allowing the light source and the optical measuring instruments to be positioned outside the cavity under investigation during the measurement operation.

The device may be equipped with a rotating drive which allows the rotation of the diameters measuring device and which allows the examination of different areas of the interior walls in succession.

In addition to the camera, at least one colour sensor may be provided to determine the colour of interior walls of a hollow body; electronic control and evaluation devices may be provided to compare colours of interior walls determined by the colour sensor with specified values and, depending on the comparison, to give a quality statement on the interior walls; the specified values may be, for example, colour shades or tolerances by which colours measured in succession may differ from each other.

The electronic control and evaluation devices may be designed to make a decision on the quality of a test cavity, preferably including a sorting device, which may be designed to transport a test cavity by one of at least two different routes, one of which is selected depending on whether the quality of the hearing aid is found to be sufficient or insufficient.

The colour sensor may be rigidly coupled to the diametersometer and thus be adjusted and rotated together with it in height. The axis of rotation is preferably in the centre of the cavity being tested. The diametersometer may be so arranged that it is driven centrally or decentrally into a hollow body.

A colour resolution of the colour sensor may be more appropriate than that of the camera.

The camera system may be equipped with passenger lights and may be arranged to illuminate the area of interior walls covered by the camera system. The lights may be part of the lighting system. They may be arranged to be switched on in turn with the passenger lighting system, each of which may take at least one image. While the passenger lighting system, by reason of its arrangement, particularly highlights the unevenness of the interior walls, the lights may preferably provide a particularly homogeneous illumination. In addition, the passenger lighting system and the lighting system may emit light at different wavelengths, which may provide different information about the transformations. For homogeneous illumination, the lighting systems may be positioned at a small or small angle, about 15°, or at a 30° angle of the camera reception.

To further reduce the time required for testing, the rod-shaped camera may have several longitudinally-aligned light-entry areas for capturing several longitudinally-aligned circular images, each of which may be accompanied by an associated camera, i.e. a camera chip.

The test apparatus of the invention may also have several camera devices and several diameter measuring devices. These may be operated by a common adjustment device or at least controlled simultaneously. This allows several cavities of a hollow body to be examined simultaneously. This is useful, for example, for cylinders of an internal combustion engine. The several camera devices and several diameter measuring devices may be arranged at an adjustable distance from each other so that this distance can be adjusted to the distance between the cavities to be examined.

In a variant of the method of the invention, several images are taken in succession with the rod camera to test different height ranges of the interior walls, while the camera is inserted and/or out of the hollow body by the cameras, which allows the entire height range of the interior walls to be examined to be recorded in a short time. If images are taken only when entering or exiting, the entry or exit movement during which no image is taken can be carried out particularly quickly, which is in any case faster than the other entry or exit movement. Alternatively, images can also be taken at both the entry and exit, which results in greater data redundancy and/or measurement reliability.

The adjustment device can be operated so that it inserts the camera device into the camera along a central axis of a cavity of the hollow body. Movement along the central axis simplifies the following data analysis. For guidance along the central axis, the camera device and the hollow body restraint device may be arranged accordingly.

It may be advantageous to allow the colour sensor and the diametersimulator to examine cavities of very different diameters with precision. To this end, the drives may be designed to move the colour sensor and/or the diametersimulator transversely, in particular vertically, to a longitudinal axis of the cavity. This adjustment may be made automatically after a measurement of the distance from the colour sensor and/or the diametersimulator to a wall of the cavity. The distance can be measured with the diametersimulator. This can be advantageous for testing cavities of very different sizes with the same test device.

For a mechanically simple configuration, the camera system and the colour sensor and/or the diametric measuring device may be installed successively in the same cavity to be inspected; the camera system and the colour sensor or the diametric measuring device may be arranged in a plane perpendicular to the longitudinal axis of the cavity, e.g. rotated 180° about the longitudinal axis.

The features of the invention described as additional device features are also to be understood as variants of the process of the invention and vice versa.

Further advantages and features of the invention are described below in relation to the accompanying schematic figures, which show: Figure 1 a schematic representation of a first embodiment of a test device in accordance with the invention;Figure 2 a schematic representation of a second embodiment of a test device in accordance with the invention; andFigure 3 a schematic representation of a third embodiment of a test device in accordance with the invention.

The same and similar components are usually indicated in the figures by the same reference.

Figure 1 shows an example of a test apparatus according to the invention 100 for the examination of the inner walls 4 of a hollow body 1.

The hollow body 1 may have one or more hollows 3 each having internal walls 4 to be tested.

The test apparatus 100 shall comprise as essential components a camera apparatus 10, a passing beam lighting apparatus 20 and a diameter measuring apparatus 30.

In addition, the test fixture 100 has a restraint device, not shown here, to hold the hollow body 1 in a desired and known position.

The camera unit 10 has a rod-shaped housing. This is inserted into the cavity 3 by an adjustment device (not shown). Through a light entry area 12 at the bottom of the rod-shaped housing, the camera unit 10 can capture an image of the environment. The field of view 15 of the camera unit 10 is transversely, in particular perpendicular to its longitudinal direction defined by the rod shape. Preferably, the field of view covers a 360° angle so that a circular image can be captured.

The passing beam 20 is designed to illuminate the interior walls, whereby the passing beam 20 is arranged so that its direction of radiation 25 is transversely perpendicular to the direction of reception 15, i.e. the field of vision 15 of the camera 10. This may also be called dark-field illumination, which causes unevenness of the interior walls 4 to cast a relatively strong shadow which can then be detected by the camera 10.

The passing beam lamp 20 may provide a ring-shaped illumination which illuminates simultaneously a complete ring area of the inner walls 4.

The camera 10 can take several images while being driven into or out of the chamber 3 and can thus examine different heights of the interior walls 4.

The images taken are then evaluated by electronic control and evaluation devices (not shown), which use the criteria to decide whether the internal structures 4 examined are free of or defective.

The main idea of the invention is to use another optical measuring device to measure the diameter of the cavity 3 and to determine the thickness of the coating on the inner walls 4 or irregularities in the coating.

In the example shown, this includes several triangulation sensors 31 which are arranged so that they are directed at different points on the interior walls 4 by the camera 10 when inserted into the cavity 3.

Measurement results of the diametric device 30 are also taken into account by the control and evaluation tools to decide on error-free or faulty interior walls 4.

In the embodiment shown in Figure 2, a hollow body 1 is examined, which has several cavities 3 and 5, each with internal walls 4 and 6 to be tested.

The diameter measuring device 30 is not made by triangulation sensors, but rather by an optical distance meter 30, preferably a confocal sensor 39, which includes a waveguide 37 through which a measuring beam 34 is directed to the inner walls 6.

The colour sensor 40 can also be equipped with a waveguide and can be coupled to the spacemeasure 30 so that both can be driven into the cavity 5 simultaneously and both can be rotated together around the centre axis of the cavity 5 so that the inner walls 6 can be scanned in perimeter direction.

In the embodiment shown in Fig. 2, the diameters 30 and 10 are placed simultaneously in different cavities 3 and 5, so that they do not interfere even if their dimensions are larger, and both can be moved along a central axis of the respective cavity 3.5 which facilitates the evaluation of the measurements.

In Figure 3, the test fixture 100 comprises a camera 10 and a floodlight 20 which may be configured as shown in Figure 1 or 2. The diameter 30 and the colour sensor 40 are here set up as in Figure 2, but are coupled to the camera 10 in Figure 3 and therefore are placed together in the same cavity 3. In this case, the diametric device 30 may be placed outside the field of vision 15 of the camera 10 so that the measurements do not interfere with each other. The strip light fixture 20 and the light source of the diametric device 30 may be arranged here in succession, thus avoiding interference.

The rotation of the measuring components 10, 30, 40 and, where appropriate, the dipped-beam lighting device 20 allows successive examination of different sections of the inner walls 4; since the measuring components 30, 40 require rotation anyway, it is not necessary to design the camera device 10 to take a circular image here; instead, images of the camera device 10 taken at the same height in succession can be combined to form a circular image.

The test apparatus 100 according to the invention has the advantage of enabling the test of hollow bodies to be carried out with particular speed and reliability, eliminating defective hollow bodies without the need for any intervention by the user.

Claims (12)

1. Examining device for examining inner walls (4, 6) of a hollow body (1), in particular a cylinder bore in an engine block, having

   - a holding means for holding the hollow body (1),

   - a rod-shaped camera device (10) which is designed to record an image transversely with respect to a longitudinal axis of the rod-shaped camera device (10),

   - an adjustment means for moving the camera device (10) into and out of the hollow body (1),

   - an illumination means (20) for illuminating the inner walls (4, 6) of the hollow body (1),

   - electronic control and evaluation means which are designed to control the camera device (10) for recording a panoramic image around the longitudinal axis of the rod-shaped camera device (10), and to determine from image data recorded by the camera device (10) surface properties of the inner walls (4, 6), and

   - a diameter determination means (30) for determining an inner diameter of a cavity (3, 5) of the hollow body (1),

   wherein the control and evaluation means are designed to determine the inner diameter of the cavity (3, 5) from measurement information of the diameter determination means (30), characterised in that

   - the diameter determination means (30) has a light source (32) which is provided in addition to the illumination device (20) to emit a light beam (34) onto inner walls (4, 6) of the cavity (3, 5), and also has optical measuring means (35) which are provided in addition to the camera device (10) to detect light coming from the inner walls (4, 6) of the cavity (3, 5),

   - that the illumination device (20) comprises a grazing light illumination device (20) which is arranged so that emission directions (25) of the grazing light illumination device (20), in which it illuminates inner walls (4, 6) during operation, are transverse with respect to receiving directions (15), from which the camera device (10) receives light from the illuminated inner walls (4, 6), wherein an angle between the emission directions (25) and the receiving directions (15) is between 45° and 135° and

   - that the grazing light illumination device (20) is arranged so that it is located outside of the hollow body (1) when the camera device (10) has been moved into the hollow body (1).
2. Examining device according to claim 1, characterised in that light emitted by the grazing light illumination device (20) onto the inner walls (4, 6) is guided onto them at an angle which is smaller than 25°, preferably smaller than 10°.
3. Examining device according to claim 1 or 2, characterised in that the rod-shaped camera device (10) has a light entry area (12) at its lower end, with which it is first moved into a cavity (3, 5) of the hollow body (1), through which light entry area light can enter to record an image of the inner walls (4, 6).
4. Examining device according to one of claims 1 to 3, characterised in that the illumination device (20) is formed as a ring light which is arranged centred relative to the rod-shaped camera device (10).
5. Examining device according to one of claims 1 to 4, characterised in that the diameter determination means (30) comprises at least one triangulation sensor (31).
6. Examining device according to one of claims 1 to 5, characterised in that the diameter determination means (30) comprises a confocal sensor (39), wherein a shared optical element is provided for emitting light of the light source (32) to the inner walls (4, 6) and for guiding light from the inner walls (4, 6) to the optical measurement means (35).
7. Examining device according to one of claims 1 to 6, characterised in that the diameter determination means (30) is arranged relative to the camera device (10) so that both can be moved at the same time into different cavities (3, 5).
8. Examining device according to one of claims 1 to 7, characterised in that additionally a colour sensor (40) is provided for determining the colour of inner walls (4, 6) of a hollow body (1) and that the electronic control and evaluation means are designed to compare detected colours of inner walls (4, 6) with predefined values and to output a quality information about the inner walls (4, 6) in dependence upon the comparison.
9. Examining device according to one of claims 1 to 8, characterised in that the illumination device (20) comprises illumination means moving with on the rod-shaped camera device (10), which are arranged so that they illuminate the area of inner walls (4, 6) detected by the camera device (10) during operation.
10. Examining device according to one of claims 1 to 9, characterised in that the electronic control and evaluation means are designed for that purpose, on the basis of recorded measurement values, to reach a decision above that whether an examined hollow body (1) has a sufficient or insufficient quality, and that a sorting means is present which sorts the examined hollow body (1) according to the criterion of whether a sufficient or insufficient quality of the hollow body (1) has been determined.
11. Method for examining inner walls (4, 6) of a hollow body (1) by the examining device according to one of claims 1 to 10, characterised in that for examining the inner walls (4, 6) with the rod-shaped camera device (10), at least one image is recorded while the camera device (10) has been moved by the adjustment means into the hollow body (1), that the grazing light illumination device (20) is located outside of the hollow body (1) when the camera device (10) has been moved into the hollow body (1) and that the light source (32) emits a light beam (34) onto inner walls (4, 6) of the cavity (3, 5) and the optical measurement means (35) detect light coming from the inner walls (4, 6) of the cavity (3, 5).
12. Method according to claim 11, characterised in that the camera device (10) is moved along a middle axis of a cavity (3, 5) of the hollow body (1) into this hollow body (1).