WO2001022030A1

WO2001022030A1 - Device for geometric determination of poorly accessible hollows in one workpiece

Info

Publication number: WO2001022030A1
Application number: PCT/EP2000/009299
Authority: WO
Inventors: Frank Brosette; Mario Schroeder
Original assignee: Mycrona Gesellschaft Für Innovative Messtechnik Gmbh
Priority date: 1999-09-22
Filing date: 2000-09-22
Publication date: 2001-03-29
Also published as: EP1221018A1; AU7522100A

Abstract

The invention relates to a device for optoelectronic geometric measurement of poorly accessible hollows, cavities or cores (2, 2') in one work piece (3), especially for measuring the inside of bores (2, 2') in a hollow body (3) such as an injection bore (2, 2') on the inside of a fuel injection valve (3) for internal combustion engines. Said inventive device comprises an optoelectronic detection unit (5), optionally provided with an objective, such as a CCD-camera, with an illuminating source (10), which is located on the inside or outside of the work piece (3), for illuminating sites on the inside of said hollow or of said cavity or the cavity and also comprises an evaluation unit. A deflection mirror (4, 26) which can be placed in said recess or in a cavity (1), controls the optical axis (12) of said optoelectronic detection unit (5), whereby a beam of light (6) emanating from an illuminating source (10) can be brought into the optical axis (12) of said detection unit (5) and directed to said deflection mirror (4) wherefrom the beam of light (6) shines on the site on the inside of said recess or of said cavity or of said bore i.e. an inlet bore (1) or injection bore (2, 2'), and said reflected beam of light can be directed by said deflection mirror (4) to the detection unit (5). Said deflection mirror (4) is located at the lower end of a holder (13) which at least can be elevated.

Description

Device for measuring the geometry of recesses difficult to access in a workpiece

TECHNICAL FIELD: The invention relates to a device for optoelectronic geometry measurement of difficult-to-access cutouts, cavities or bores in a workpiece, in particular for the internal measurement of bores in the wall of a hollow body, such as injection bores in the interior of a fuel injection valve for internal combustion engines.

State of the art:

DE 196 11 613 AI discloses a method and a device for measuring bores, in particular injection bores on fuel injection valves for internal combustion engines, in which the object to be measured is clamped in a holding device and measured with a measuring device. The position and geometry of the bore to be measured is determined using an optoelectronic measuring method. For this purpose, the object to be measured is adjusted in a geometrically defined position by means of the recording device before the measuring process, the leading edges and the trailing edges of the bore to be measured being successively measured using an optoelectronic measuring device, such as a CCD camera, during the measuring process. Before the measuring process, an illumination source, such as a light source, is introduced into the interior of the injection valve. The geometric position of the object is converted in the recording device and the measurement results of the optoelectronic measurement method in a connected evaluation unit by means of a corresponding evaluation program into geometric data of the bore to be measured. A camera is provided, the optical axis of which is coaxial with the axis of the bore to be measured. The receiving device for holding the object to be measured is formed by a chuck that can be freely moved in three planes and pivoted about three axes. Light guides are used for lighting, which are inserted into an axial bore of the valve body of the fuel injection valve, from which the injection bore to be measured leads away. However, this measurement method has

the disadvantage that the measurement of the lower edge of the bore, that is the inlet bore, which is located inside the valve, takes place through the borehole itself. An optical aperture is created through the hole, which falsifies the measurement by means of the optoelectronic measuring device. If the bores are very small, such an inlet bore or the lower edge of the bore channel can therefore no longer be measured using the aforementioned method.

Technical task:

The invention has for its object to provide a device of the type mentioned, with the difficult to access holes in workpieces, especially holes in hollow bodies, such as sleeve-like or tubular hollow bodies, in particular small holes located therein with a very small diameter of the inlet bore, exactly and completely can be measured.

Disclosure of the invention and its advantages:

The object is achieved by a device for optoelectronic geometry measurement of recesses, cavities or bores in a workpiece that are difficult to access, in particular for the internal measurement of bores in the wall of a hollow body, such as injection bores in the interior of a fuel injection valve for internal combustion engines, with an optoelectronic detection device, if appropriate with a lens, such as a CCD camera, with an illumination source that is located inside or outside the workpiece, for illuminating a location to be imaged inside the recess or the cavity or the bore, and with an evaluation device, with a deflecting mirror that goes into the Recess or the cavity can be placed, which deflects the optical axis of the optoelectronic detection device, a beam of rays emanating from the illumination source being introduced into the optical axis of the detection device and onto the deflecting mirror l is directed from where the beam of rays falls on the location to be imaged inside the recess or the cavity or the bore, such as the inlet bore or injection bore, and the reflected light can be deflected via the deflection mirror into the detection device, the deflection mirror at the lower end of one at least in height movable bracket is arranged. In a further embodiment of the device, a prism is used instead of the deflection mirror. In a further advantageous embodiment, the beam is reflected into the optical axis of the detection device by means of a beam splitter and directed onto the deflection mirror, from where it falls on the location to be imaged or the injection hole, and the reflected beam or diffusely reflected light via the deflection mirror through the beam splitter is steerable into the detection device. Both specular and diffusely reflecting points or locations can be depicted sharply.

In a further embodiment of the device, both the illumination source and the beam splitter, which is located away from the lower end of the holder, are arranged on the holder in addition to the deflecting mirror or prism. In a further embodiment, the deflection mirror and / or the beam splitter can be changed in their geometric position with respect to the holder.

In a further preferred embodiment of the device, the holder is a sleeve which has the deflecting mirror at its lower end facing the workpiece or retractable into the recess or the cavity or the hollow body, above which the beam splitter is located in the area of the other end in the sleeve is located and the sleeve in the area of the deflecting mirror and optionally in the area of the beam splitter has openings for the passage of the beam. In order to determine the coordinates of the location to be imaged, the holder can be arranged in at least one of the three spatial directions and, if necessary, rotatable by at least one angle.

In a further preferred embodiment of the device, the workpiece for determining its coordinates is also in a geometrically measurable position and is arranged to be movable and rotatable through at least one angle in at least one of the three spatial directions. This means that both the workpiece and - preferably independently of it - the sleeve are in a geometrically defined position, so that the coordinates of the workpiece and or sleeve can be specified with the measurement. In this way, any location within the workpiece can be measured or mapped. In a further embodiment, the sleeve is fixedly connected to the optoelectronic detection device, which is located outside the workpiece or the hollow body, by means of a support arm.

Furthermore, the sleeve can have a single or multiple kink, with a beam deflection or beam deflection device being located in the area of each kink. This design has the advantage that it can be used for measuring undercuts or can be seen "around the corner" with it.

In a further embodiment of the device, at least one optical system, such as a lens, is arranged within the beam path between the deflection mirror and the beam splitter.

In a further embodiment of the device, the bore is irradiated from outside the workpiece or the hollow body at its end opposite the deflecting mirror or the sleeve by means of an illumination source, so that radiation falls through the bore from the outside.

In a further embodiment of the device, the deflecting mirror has at least two deflecting surfaces, which converge in an inverted V-shape, namely Λ-shaped, at an angle; this deflecting mirror thus represents a double mirror. In this way, a distance can be determined which arises between the two focal points of the two mirror halves. This distance can be changed by moving the optoelectronic detection device, such as a CCD camera, or the lens, so that a cone can be scanned from the inside. For this purpose, the movable units, namely camera, lens and workpiece, must be equipped with a measuring device for geometric measurement. The inside of a cone of a workpiece can then be measured by evaluating the measuring positions. Furthermore, the bore can be from outside the workpiece or the

Hollow body are irradiated at their end opposite the deflecting mirror or the sleeve by means of an illumination source, so that radiation, in particular visible light, falls through the bore from the outside.

Brief description of the drawing, in which:

Figure 1 is a schematic diagram of the device for displaying the optical

Elements for measuring a very small hole,

2 shows a technical embodiment of the device, FIG. 3 shows another example of a device for measuring any location within a workpiece with an inner cone, the workpiece, optoelectronic detection device and objective and optionally deflecting mirror being movable relative to one another,

Figure 4 shows an example of the device of Figure 3, wherein the deflecting mirror is a double mirror for measuring the inner cone and

Figure 5 shows the example of the device according to Figure 4 to illustrate the

Distance change when moving the CCD camera or the lens.

WAYS OF CARRYING OUT THE INVENTION:

1 and 2, a hollow body is shown in section, which here is a fuel injection valve 3, which has bore channels 2, 2 'as injection bores of the fuel injection valve 3, the central axes 19, 19' of which are inclined differently. The bore channel 2 has a lower edge 1 of the bore, also called an inlet bore, which is arranged deep in the region of the lower end of the fuel injection valve 3 due to the position of the injection bore 2. The workpiece 3 can be adjusted in a geometrically defined position by means of a holding device (not shown), wherein the geometric position of the workpiece 3 can be changed in a predeterminable manner that can be evaluated by measurement technology.

In the fuel injection valve 3, a deflection mirror 4 is inserted into the lower end thereof, which is used to measure the inlet bore 1 of the injection channel 2 the inlet hole 1 is positioned. The deflecting mirror 4 can be a surface deflecting mirror or a prism. Light from an illumination source 10 outside the fuel injection valve 3 is directed onto the deflection mirror 4 via an arranged beam splitter 11, which is preferably located outside the fuel injection valve 3 and is located between an optoelectronic detection device 5 and the deflection mirror 4, so that the beam from the illumination source 10, delimited by edge rays 6 of the beam path, onto which deflecting mirror 4 falls. The deflecting mirror 4 is aligned such that the beam path preferably falls perpendicularly onto the wall 7 of the fuel injection valve 3 and thus onto the inlet bore 1.

In order to be able to illuminate the fuel injection valve 3 in its interior, the radiation, preferably light from the illumination source 10, is reflected in the optical axis 12 of an optoelectronic detection device, which is, for example, a CCD camera. In the example shown, the detection device 5 is located behind the beam splitter 11. The light reflected or diffusely scattered back from the measurement point or from the surface of the measurement point is fed to the detection device 5 via the deflection mirror 4.

Figure 2 shows a technical embodiment of the device, consisting of a tubular, elongated-narrow sleeve 13 or tube, which dips with its tip into the inner bore 20 of the fuel injector 3. The deflection mirror 4 is located within the lower, immersed end of the sleeve 13 or the tube 13, the sleeve 13 having an opening 15 at the lower end for the passage of the beam 6 from the light source 10. In the region of the upper end of the sleeve 13, which protrudes from the fuel injector 3, the jet is expensive 11 inclined, which is installed in the tube 13. To the side of the beam splitter 11, the wall of the sleeve 13 has a further opening 14 for the passage of light from the light source 10. The sleeve 13 is fixedly connected to the optoelectronic detection device 5 by means of a support arm 16, so that the detection device 5, the support arm 16 and the Sleeve 13, and thus the beam splitter 11 and the deflecting mirror 4, form a unit, which can move in the three spatial axes and can also be swiveled if necessary.

A further optical system can be arranged inside the sleeve 13 or the tube 13, consisting, for example, of lenses 17, 18.

To measure different bores 2, 2 ', the central axes 19, 19' of which may be inclined to one another, the workpiece 3 is correspondingly rotated about its central axis 8, which in the example of FIG. 2 coincides with the optical axis 12 of the detection device 5 until the respective inlet bore is detected by the beam path 6. The different spatial position of the inlet bores 1 of the bore channels 2, 2 'in FIG. 2 and thus their different geometric representation in the image plane of the detection device 5 can be converted using a computer program in order to determine the exact cross sections of the inlet bores in this way.

FIGS. 3 to 5 show further examples of the device for measuring any location within a workpiece 21 and for measuring inner cones 22 of a workpiece 21. The workpiece 21 has an inner cone 22, into which the mirror 4, which is attached to a holder, not shown, is inserted. The measuring arrangement also includes the optoelectronic detection device, such as a CCD camera 5, the beam splitter 11 and a lens 17, which focuses a selected point 23 or location 23 on the inner surface 22 of the inner cone. The workpiece 21, the lens 17 and the CCD camera 5 are each equipped with a measuring device 24, 24 ', 24 "for determining coordinates, so that when moving the workpiece 21, lens 17 and possibly the CCD camera 5 further locations or Points can be imaged sharply on the inner conical surface 22. The double arrows indicate the main direction of movement in the z-axis direction, although it is possible to move and pivot in all coordinate directions and solid angles. If, instead of a simple deflecting mirror 4, a double mirror 26 is used, as shown in FIGS. 4 and 5, a distance s and s' can be determined. The distance s is the mutual distance between the two focus points 25, 25 'on the inner surface 22 of the inner cone of the workpiece 21. The double mirror 26 has the two mirror surfaces 27, 27', which are reversely V-shaped at an angle with respect to the Lens 17 converge inclined, the upper common edge facing lens 17, as can be seen from FIGS. 4 and 5.

The distance between the two focus points can be changed by moving either the CCD camera 5 or the lens 17 or, if appropriate, the workpiece 21, which can be seen from FIG. 5. With each relative movement of the workpiece 21 with respect to the double mirror 26 and refocusing by means of the objective 17 and possibly the CCD camera 5, other pairs of points 28, 28 ′ can be imaged sharply, so that the inner cone 22 of the workpiece 21 can be scanned. For this purpose, the movable units, such as workpiece, lens and CCD camera, have measuring devices 24, 24 ', 24 "(FIG. 3). The inner cone 22 can be measured by evaluating the measuring positions, so that the cone opening angle α can also be determined ,

Industrial applicability:

The invention can be used, for example, for the geometry measurement of recesses, cavities or bores in a workpiece that are difficult to access, in particular for the internal measurement of bores in a hollow body, such as injection bores in the interior of a fuel injection valve for internal combustion engines. List of reference numerals:

I Inlet hole 2, 2 'drill channel

3 fuel injector 4 deflection mirror

5 optoelectronic detection device, CCD camera

6 beam path

7 wall

8 longitudinal axis 9 focal plane

10, 10 'light source

I I beam splitter

12 optical axis of 5

13 tube 14.15 opening

17.18 optical systems. lenses

19 central axis of the bore

20 interior of 3

21 hollow cone 22 inner surface of the hollow cone

23, 25, 25 ', 28, 28' sharp points on the inner surface of 21

24, 24 ', 24 "movement arrows with measuring devices 26 double mirrors 27, 27' mirror surface halves of the double mirror

Claims

claims:

1. Device for optoelectronic geometry measurement of recesses, cavities or bores (2,2 ') which are difficult to access in a workpiece (3), in particular for the internal measurement of bores (2,2') in the wall of a hollow body (3), such as injection bores ( 2,2 ') inside a fuel injection valve (3) for internal combustion engines, with an optoelectronic detection device (5), optionally with an objective such as a CCD camera, with an illumination source (10) which is located inside or outside the workpiece (3) , for illuminating a location to be imaged inside the recess or the cavity or the bore as well as with an evaluation device, with a deflecting mirror (4,26) which can be placed in the recess or the cavity (1) which defines the optical axis (12) deflects the optoelectronic detection device (5), a beam (6) emanating from the illumination source (10) into the optical axis (12) of the detection device Attention (5) is introduced and directed to the deflecting mirror (4), from where the beam (6) to the location to be imaged inside the recess or cavity or bore, such as inlet bore (1) or injection bore (2,2 ') , falls, and the reflected light can be deflected via the deflecting mirror (4) into the detection device (5), the deflecting mirror (4j being arranged at the lower end of a holder (13) which can be moved at least in height.

2. Device according to claim 1, characterized in that the beam (6) is reflected by means of a beam splitter (11) in the optical axis (12) of the detection device (5) and directed onto the deflecting mirror (4,26), from where it is falls on the location to be imaged or the injection bore (2,2 '), and the reflected beam can be directed via the deflecting mirror (4) through the beam splitter (11) into the detection device (5).

3. Device according to claim 1 or 2, characterized in that on the bracket (13) both the lighting source (10) and the beam expensive (11) are arranged, which is located from the lower end of the bracket (13).

4. The device according to claim 2 or 3, characterized in that the deflecting mirror (4) and / or the beam splitter (11) can be changed in their geometric position with respect to the holder (13).

5. The device according to claim 2 or 3, characterized in that the holder is a sleeve (13) which on its lower, the workpiece (3) facing or in the recess or the cavity or the hollow body (3) retractable end of the deflecting mirror (4), above it in the area of the other end in the sleeve (13) there is the beam splitter (11) and the sleeve (13) in the area of the deflecting mirror (4) and optionally in the area of the beam splitter (11) openings (14 , 15) for the passage of the beam (6).

6. Device according to one of the preceding claims, characterized in that the holder (13) for determining the coordinates of the location to be imaged (1,23, 25,25 ', 28,28') can be moved in the three spatial directions and, if necessary, rotated by at least an angle is arranged.

7. Device according to one of the preceding claims, characterized in that the workpiece (3) for determining its coordinates is in a geometrically measurable position and is arranged to be movable and rotatable in the three spatial directions by at least one solid angle.

8. Device according to one of the preceding claims, characterized in that the sleeve (13) by means of a support arm (16) is fixedly connected to the optoelectronic detection device (5), which is outside the workpiece (3) or the hollow body (3) located.

9. The device according to claim 6 or 8, characterized in that the sleeve (13) is designed kinked, with a beam deflection or beam deflection device being located in the region of each kink.

10. Device according to one of the preceding claims, characterized in that instead of the deflecting mirror (4,26) or the

Double mirror (26) a prism is used.

11. Device according to one of the preceding claims, characterized in that there are at least one optical system (17, 18), such as lens (17, 18), within the beam path (6) between the deflecting mirror (4) and the beam splitter (11).

12. Device according to one of the preceding claims, characterized in that the bore (2, 2 ') from outside the workpiece or the hollow body (3) at its end opposite the deflecting mirror (4) or the sleeve by means of an illumination source (10 ') is irradiated so that radiation falls through the bore (2, 2') from the outside.

13. The apparatus according to claim 1, characterized in that the deflecting mirror (26) has at least two deflecting surfaces (27, 27 ') which converge at an angle.