Abstract
The invention relates to a device for measuring the geometry of the inner wall of bores, drill holes and passages, which are optionally countersunk, and in particular for threaded, pin, and rivet connections of workpieces, said device comprising at least one optical sensor measuring towards the inner wall and capable of being introduced into the drill hole and rotated via a feed/rotating unit, wherein an auxiliary object is provided with a passage and rests on the surface of the workpiece, through which passage said sensor is inserted into the countersink and/or bore. The device is characterized in that the inner wall of the auxiliary object is provided with a structure and that the sensor scans said structure(s) while passing through the auxiliary object. The invention also relates to a corresponding method.
Claims
1. A device for measuring a geometry of an inner wall of bores, drill holes and passages, which are optionally countersunk, and in particular for threaded, pin, and rivet connections of workpieces, said device comprising: at least one optical sensor that measures towards the inner wall and is capable of being introduced into a drill hole and rotated via a feed/rotating unit, wherein an auxiliary object is provided with a passage and rests on a surface of a workpiece, the sensor is inserted through the passage into a countersink and/or a bore, the inner wall of the auxiliary object is provided with a structure and the sensor scans said structure while passing through the auxiliary object.
2. The device of claim 1, wherein a distance to the structure is known due to precise manufacturing.
3. The device of claim 1, wherein a distance to the structure is determined by means of measurement and calibration.
4. The device of claim 1, wherein the structure is rotationally symmetrical.
5. The device of claim 1, wherein an axial distance of the structure to respective edges of the passage of the auxiliary object is known.
6. The device of claim 1, wherein the structure has clear geometrical features.
7. The device of claim 1, wherein the structure is formed by at least one of corners, edges, shoulders, and differences in brightness, material, and surface finish.
8. The device of claim 6, wherein the structure is formed by a succession of straight and sloped or angled portions.
9. A method for measuring a geometry of an inner wall of bores, drill holes and passages, which are optionally countersunk, and in particular for threaded, pin, and rivet connections of workpieces, wherein one optical sensor measuring towards the inner wall is introduced into a drill hole and rotated via a feed/rotating unit, wherein an auxiliary object is provided with a passage and rests on a surface of a workpiece, the sensor is inserted through the passage into a countersink and/or a bore, the inner wall of the auxiliary object is provided with a structure, the sensor scans said structure while passing through the auxiliary object, and transition points, in particular at least one of corners, edges, and differences in brightness, material, and surface finish are determined by fitting curves, for example, straight lines, circular arcs, or other shapes, to readings and by subsequently calculating their intersections, wherein the intersections define the transition points.
10. The method of claim 9, wherein the readings of the structure are approximated to straight lines or polynomials by mathematical functions or algorithms.
Description
[0033] There are different possibilities to configure and enhance the teaching of the present invention in an advantageous manner, which arise on the one hand from the claims subordinate to claim 1, and on the other hand from the following description of preferred exemplary embodiments of the invention with reference to the drawings. In association with the description of the referred exemplary embodiments of the invention with reference to the drawings, the generally preferred configurations and enhancements of the teaching will also be described. In the drawings,
[0034] FIG. 1 shows a schematic view of the number of geometric ratios in the connection of two workpieces,
[0035] FIG. 2 shows a schematic view of a measuring operation using a prior art optical sensor,
[0036] FIG. 3 shows a schematic view of a specific configuration/arrangement of a measuring device with auxiliary object,
[0037] FIG. 4 shows a diagram of a profile of the measurement in accordance with the measuring device in FIG. 3,
[0038] FIG. 5a shows a schematic view of an exemplary embodiment of an auxiliary object of a device according to the invention,
[0039] FIG. 5b shows a schematic view of an exemplary embodiment of another auxiliary object of a device according to the invention,
[0040] FIG. 5c shows a schematic view of an exemplary embodiment of another auxiliary
[0041] FIG. 6 shows a schematic view of an exemplary embodiment of another auxiliary object of a device according to the invention,
[0042] FIG. 7 shows a schematic view of an exemplary embodiment of another auxiliary object of a device according to the invention,
[0043] FIG. 8 shows a schematic view of an exemplary embodiment of another auxiliary object of a device according to the invention,
[0044] FIG. 9 shows a schematic view of the measuring device over the course of a feed of the sensor that moves over the edge of the cone prior to introduction into the bore, and
[0045] FIG. 10 shows a diagram of the profile of the measurement in accordance with the measuring device in FIG. 9.
[0046] FIG. 1 shows the geometric ratios 1 in the connection of two workpieces 2, 3. Said bore 4 has a countersink 5 to prevent the screw or rivet head from extending beyond the workpiece surface. On the upper edge of said countersink 5, a small shoulder 6 may be disposed. Numerous geometric features may be measured: the depth of shoulder 7 or countersink 8, the diameter of shoulder 10 or bore 9, the angle 11 of the countersink, or the total thickness of the two connected workpieces. It is necessary to verify the readings to avoid the screws or rivets installed in the subsequent threading or riveting process protruding above the surface or sitting too deep in the drill hole. These criteria are essential for the stability and durability of the threaded or rivet connection.
[0047] FIG. 2 shows the measuring process for the inner diameter 9 of bore 4. A measuring device 12 includes a sensor 13, which is introduced via a feed/rotating unit (not shown for the sake of convenience) into the drill hole and rotated therein. With one or more rotations of sensor 13, the inner diameter 9 of bore 4 can be measured by scanning with the measuring beam 14. Using the feed unit, this can take place at several depth positions of the bore 4.
[0048] FIG. 3 shows the measuring device 12 with sensor 13 and an auxiliary object 15, which is pushed against the surface of the workpiece 2 during the feed of the measurement device 12 by means of a spring 16. Sensor 13 is then inserted through the auxiliary object 15 into the countersink 5 or bore 4. During the feed movement, the profile of the auxiliary object 15 as well as the profiles of the shoulder 6 and the countersink 5 are recorded.
[0049] FIG. 4 shows the profile of the measurement in FIG. 3. Zone A depicts the inner contour of the auxiliary object 15 a,b. Zone B corresponds to the shoulder 6, zone C to the countersink 5, and zone D to the bore 4. The distortions of the readings are clearly visible at the transition between A and B (transition 17, edge of the auxiliary object to the upper edge of the workpiece) as well as B and C (transition 18 from shoulder 6 to countersink 5). These readings cannot be referenced for an exact determination of the position of the edge or of the transition.
[0050] FIG. 5a shows an exemplary configuration of the auxiliary object 15. On the inside of the auxiliary object, a step 19 is machined, for example by means of rotation. The edge of said step 19 has a known distance 21 to the edge of the auxiliary object 20. The inner diameter 9 after said step towards the edge is selected as to not to exceed the measuring range of sensor 13. The measuring beam 14 thus delivers valid readings.
[0051] FIG. 5b shows another exemplary configuration of the auxiliary object 15. On the inside of the auxiliary object 15, the structure of the surface shows a change in texture. Here, a change of brightness is depicted. In the upper part 15a, the inner surface is bright, in the lower part 15b on the other hand, it is dark. The change takes place at location 19, so that said location has a known distance 21 to the edge of the auxiliary object 15. The sensor 13 recognizes the change in surface finish on the edge 19, for example by evaluating the intensity signal. Likewise, other structures may be affixed to the inside, for instance color changes or changes in gloss level. This is shown by way of example in FIG. 5c.
[0052] According to FIG. 5c, the inner surface of the auxiliary object 15 is structured by color (upper part 15a, lower part 15b) with changing light-dark-transitions between the parts. The distance to the edge 20 of the auxiliary object 15 may be determined from the known position of the transitions 19, 19, 19, 19.
[0053] FIG. 6 shows another exemplary configuration of the auxiliary object 15. On the inside of the auxiliary object, two steps 19, 19 are machined. The edge of the first step (19) has a known distance 21 to the edge 20 of the auxiliary object 15, the edge of the second step 19 has a known distance 21 to the edge of the auxiliary object.
[0054] FIG. 7 shows another exemplary configuration of the auxiliary object 15. On the inside of the auxiliary object, a slope (cone) 22 is machined, for example by rotation. The edge 19 of the transition to said cone 22 has a known distance 21 to the edge of the auxiliary object 20.
[0055] FIG. 8 shows another exemplary configuration of the auxiliary object 15. On the inside of the auxiliary object, a slope (cone) 22 is machined, for example by rotation, which adjoins again an area with a constant diameter 23. The first edge 19 of the transition to the cone 22 has a known distance 21 to the edge 20 of the auxiliary object 15, the second edge 19 of the transition has a second known distance 21 to the edge of the auxiliary object. By piecewise fitting straight lines to the readings, one obtains two intersections 19, 19 that can be determined with high accuracy.
[0056] FIG. 9 shows the measuring arrangement over the course of feeding the sensor 13 over the edge of the cone prior to introduction into the bore. In this unfavorable case, the diameter of the shoulder 6 is about the same size as the diameter of the slope 22 on the edge of the auxiliary object. When the sensor 13 passes, the detection on the edge 20 of the auxiliary object would be made difficult or even impossible. By fitting straight lines into the piecewise straight portions (slope, interior diameter, countersink), the intersection and thus the start point of the measured object can be determined exactly.
[0057] FIG. 10 shows an exemplary result of a measurement while the sensor is fed into the bore. Noise can be seen in the measuring signal, resulting, on the one hand, from surface properties of the auxiliary object or the bore/countersink, and on the other hand within the sensor itself. The signal dropout or distortion is particularly clear in the transition points between straight pieces and sloped pieces, for instance at location 24 on the auxiliary objet, or at the transition point between auxiliary object and countersink 25. By the piecewise fitting of straight lines to the measurement points, averaging and smoothing can be achieved. On the readings for the auxiliary object in the upper, straight part, a straight line 26 is fitted, and in the following sloped part a second straight line 27. The intersection of the straight line then provides the exact position of transition point 19. This allows determining exact intersections, which makes it possible to accurately determine the position of the edge 20. Likewise, the fitting line in the lower cylindrical part of the auxiliary object 28 intersects with the fitting line of the cone part, which defines transition point 19.
[0058] The knowledge of the exact position of the transition points 19, 19 from the CAD data or by calibration therefore allows determining the exact position of the edge of the auxiliary object. Thus, the exact position of the upper edge of the countersink is also determined when mounting the auxiliary object on the countersink.
[0059] The same applies to countersink 5 and bore 4, where straight lines 29, 30 are fitted, the intersection of which establishes the transition point 31 and thus the end of the countersink.
[0060] With regard to additional advantageous configurations of the teaching of the invention, it is referred to the general part of the description as well as the attached claims in order to avoid repetitions.
[0061] Finally, it is noted expressly that the exemplary embodiments of the teaching of the invention described above merely serve to illustrate the claimed teaching without limiting it to the exemplary embodiments.
REFERENCE LIST
[0062] 1 Geometric ratios [0063] 2 Workpiece [0064] 3 Workpiece [0065] 4 Bore [0066] 5 Countersink of the bore [0067] 6 Shoulder on the upper edge of the countersink [0068] 7 Depth of the shoulder [0069] 8 Depth of the countersink [0070] 9 Diameter of the bore, inner diameter [0071] 10 Diameter of the shoulder [0072] 11 Angle [0073] 12 Measuring device [0074] 13 Sensor [0075] 14 Measuring beam [0076] 15a Auxiliary object, upper part [0077] 15b Auxiliary object, lower part [0078] 16 Spring [0079] 17 Transition between zone A and zone B [0080] 18 Transition between zone B and zone C [0081] 19, 19, 19 Step, edge [0082] 20 Edge of the auxiliary object [0083] 21, 21, 21 Distance to the edge of the auxiliary object [0084] 22 Slope, cone [0085] 23 Zone with constant diameter [0086] 24 Location [0087] 25 Transition point between auxiliary object and countersink [0088] 26 First straight line [0089] 27 Second straight line [0090] 28 Straight line [0091] 29 Straight line [0092] 30 Curve, straight line [0093] 31 Transition point
