APPARATUS FOR MEASURING A THREAD

Abstract

The invention relates to an apparatus for measuring a thread (1), comprising a holder for detachably holding a tube (2), wherein the thread (1) is formed at one end of the tube (2), a first optical measuring section (5) having an optical sensor (5a), wherein the optical measuring section (5) is attached to a manipulator (3) in order to move the measuring section (5) relative to the tube (2), and wherein the optical measuring section (5) is adjustably tiltable about a first adjusting axis (S1) relative to a thread axis (A) of the thread (1), wherein a second optical measuring section (5) having a second optical sensor (5a) is arranged at the manipulator (3), wherein the optical measuring sections (5) overall form a measuring channel (4) for simultaneous measurement of opposite sides of the thread (1).

Claims

1. A device for measuring a thread (1), comprising a holder for the detachable holding of a tube (2), wherein the thread (1) is formed on an end of the tube (2), a first optical measuring section (5) with an optical sensor (5a), wherein the optical measuring section (5) is attached on a manipulator (3) in order to move the measuring section (5) relative to the tube (2), and wherein the optical measuring section (5) can be tilted in an adjustable manner about a first adjusting axis (S1) relative to a thread axis (A) of the thread (1), wherein a second optical measuring section (5) with the second optical sensor (5a) is arranged on the manipulator (3) wherein the optical measuring sections (5) form on the whole a measuring conduit (4) for the simultaneous measuring of opposite sides of the thread (1), characterized in that the measuring conduit (4) can be tilted by the manipulator (3) about at least one second adjusting axis (S2) relative to the thread axis (A) so that the measuring conduit (4) can be freely aligned inside an interval of a spatial angle.

2. (canceled)

3. The device according to claim 1, characterized in that an alignment of the measuring conduit (4) for the measuring of the thread (1) takes place in that as a result of the tiltings about the adjusting axes (S1, S2) an extremum of an optical width of a thread course (1a) is adjusted.

4. The device according to claim 1, characterized in that the measuring conduit (4) is arranged on a carrier (7) which can be moved about the adjusting axes (S1, S2), wherein the carrier (7) can move via a linear guide along a main direction (H).

5. The device according to claim 1, characterized in that the measuring conduit (4) is moved in a first step by the manipulator (3) into coincidence with the thread (1), wherein an alignment of the measuring conduit (4) with the thread axis (A) takes place, and that the measuring conduit (4) is moved out of the coincidence in a second step in the opposite direction, wherein a measuring of the thread (1) takes place.

6. The device according to claim 1, characterized in that the manipulator (3) comprises a freely movable industrial robot (6) or a comparable robot.

7. The device according to claim 1, characterized in that at least one second measuring conduit (8) is arranged on the manipulator (3), wherein the measuring conduits (4, 8) are aligned on different areas of the thread (1) in its circumferential direction.

8. The device according to claim 1, characterized in that at least one light-section sensor (9) is additionally arranged on the manipulator, wherein the surface of a preferably undercut thread flank (1a) can be measured by the light-section sensor (9).

9. The device according to claim 8, characterized in that at least one second light-section sensor (10) is arranged on the manipulator (3), wherein an opposing flank of the thread course (1a) can be measured by the second light-section sensor (10).

10. The device according to claim 1, characterized in that one of the optical measuring sections (5) comprises an optical measuring instrument selected from the group of telecentric lens, laser scanner or laser triangulator or LCD light band scanner (-meter).

11. The device according to claim 1, characterized in that the tube (2) is not moved during the entire measuring.

12. The device according to claim 1, characterized in that the measuring of the thread (1) takes place completely without a mechanical contact of a measuring sensor.

Description

[0024] Preferred exemplary embodiments of the invention are described in the following and are explained in detail using the attached drawings.

[0025] FIG. 1 shows a schematic total view of a first exemplary embodiment of an apparatus according to the invention.

[0026] FIG. 2 shows a detailed side view of the apparatus of FIG. 1.

[0027] FIG. 3 shows a view of an optical measuring section of the apparatus of FIG. 1.

[0028] FIG. 4 shows a top view onto a measuring conduit of the apparatus of FIG. 1.

[0029] FIG. 5 shows a detailed view of a second exemplary embodiment of the invention with two measuring conduits.

[0030] FIG. 6 shows a sketch for explaining an alignment procedure by the apparatus of FIG. 1.

[0031] FIG. 7 shows a view of an undercut thread.

[0032] FIG. 8 Shows a schematic view of a third exemplary embodiment of the invention with two light-section sensors.

[0033] The apparatus shown in FIG. 1 serves to measure a thread 1 which was cut in a previous manufacturing step on the end of a tube 2. The measuring serves for quality control. Depending on the requirements, the measuring can be made by taking samples. Each thread produced is preferably checked by the apparatus.

[0034] The tube 2 is firmly held during the measuring an especially rigid holder (not shown). The tube does not experience any movement or rotation during the measuring.

[0035] The apparatus according to the invention comprises a manipulator 3 with which a measuring conduit 4 with two optical measuring sections 5 can be moved in space. The manipulator 3 comprises in the present instance, for example, a universal industrial robot 6. An arm of the robot comprises several segments 6a which can pivot relative to each other via articulations 6b. A carrier 7 as another part of the manipulator is attached to the end of the arm in which carries the measuring conduit 4.

[0036] The measuring conduit 7 can be moved back-and-forth with a high degree of accuracy linearly along a main direction H by a linear guide (not shown). In the view according to FIG. 1 the main direction H runs vertically to the plane of the drawing. A thread axis A is defined as the central axis of symmetry of the thread 1 by the thread 1.

[0037] The carrier 7 can be freely moved in space by the industrial robot 6. In particular, this comprises not only a translatory movement but also a free adjustment in an interval of a spatial angle. In this manner the main direction H of the carrier can be aligned parallel to the thread axis A even in the case of an oblique state directed in any manner within the interval of the spatial angle.

[0038] This alignment can also take place when using a universal industrial robot by a simultaneous moving of several segments and articulations. FIG. 2 shows two adjusting axes S1, S2 for schematically illustrating the free adjustability of the direction. The adjusting axes S and S2 and the thread axis A should not be parallel to each other. The three axes preferably stand vertically on each other.

[0039] In this manner the main direction H and/or an orientation of the measuring conduit 4 can be brought into any direction by tilting about two adjusting axes S1, S2. In the present sense, the tilting around at least two adjusting axes S1, S2 is understood as equivalent to a free adjusting of direction (two degrees of freedom of the spatial direction) of the measuring conduit 4. As regards the realization of the tilting, any desired number and combination of moved articulations, guides, etc. can be provided on the manipulator, which is illustrated by the universal industrial robot 6.

[0040] FIG. 3 illustrates a few possibilities of the adjusting of the optical measuring sections 5. In the present instance, the optical measuring sections 5 are each a telecentric lens in which a beam path onto an optical sensor 5a, which path is parallel on the object side, is illustrated.

[0041] At first, an optical axis of the measuring section 5 can be pre-adjusted by an angle relative to the carrier 7 and/or relative to a second optical measuring section of the same measuring conduit 4. As a result, for example, the theoretical rise of the cut thread can be adjusted.

[0042] In addition, the distance between the optical sensor 5a and a light source 5b of the optical measuring section can be adjusted. Furthermore, the position of the measuring section can be adjusted along its optical axis. On the whole, this can achieve an adaptation to different tube diameters and tube holders. Just like the pre-adjusting according to the thread rise, these adjustments can take place once before a continuous series measuring of tubes with the same production. To this end, adjustable holders (not shown) are advantageously arranged on the carrier 7.

[0043] In the right illustration in FIG. 3, the movement of the measuring conduit 4 is indicated by moving the carrier 7 along the main direction H.

[0044] FIG. 4 shows a schematic view of the measuring conduit 4 aligned over the thread 1 according to the first exemplary embodiment of the invention.

[0045] FIG. 5 shows a second exemplary embodiment of the invention in which a second measuring conduit 8 is arranged on the carrier 7. The second measuring conduit 8 is arranged rotated about the main direction H by 90 opposite the first measuring conduit 4 but otherwise has the same construction. As a result, different areas along the circumference of the thread 1 can be measured. In addition, information about an ovality of the tube 2 or of the thread 1 can be obtained in this way without the tube 2 having to be rotated in its holder. For construction reasons, the second measuring conduit 8 in the main direction H can be arranged in another plane than the first measuring conduit.

[0046] In other exemplary embodiments (not shown) even three or more measuring conduits 4 can be provided which can be rotated to each other by an appropriate angle, approximately 60 in the case of three measuring conduits.

[0047] FIG. 6 shows the procedure of the alignment of the measuring conduit 4 and of the main direction H relative to the thread axis A.

[0048] In the case of an oblique state or an existing angle between the straight lines A and H (case NG in the sketch), the projections of a thread course 1a are shaded along the optical axis of the measuring sections 5. A profile of the thread course measured with the optical sensor corresponds to the course NG sketched in dotted lines. The apparent width of the thread course is enlarged and the width of the free passage of light is reduced. Given an optimal alignment of the main direction H parallel to the thread axis A, the profile width of the thread course is minimal and the width of the free passage of light is maximal. The aligned state is achieved in that the tilting around both adjusting axes S1, S2 is carried out until the measured profile has appropriate extremal values.

[0049] FIG. 7 shows a schematic profile of a thread course with an undercut on one side. The undercut thread flank is shown in dotted lines and can be detected purely geometrically only insufficiently by the optical measuring sections.

[0050] A first light-section sensor 9 is arranged according to the first exemplary embodiment (see FIG. 2) on the carrier 7 in addition to the measuring conduit 4 and is directed at a geometrically suitable angle onto the undercut thread flank. A course of the surface of the thread flank illustrated as a cross section can be measured by the light-section sensor. This makes it possible to detect, for example, whether a break in the tool during the production of the thread resulted in a deformed surface.

[0051] In the third exemplary embodiment sketched in FIG. 8, in addition to the first light-section sensor 9 a second light-section sensor 10 is provided which is directed onto the opposite thread flank. As a result, the surfaces of both thread flanks can be rapidly and reliably checked. The measuring conduit 4 is not shown in FIG. 8.

[0052] It is understood that the specific features of the individual exemplary embodiments can be logically combined with each other as required.

[0053] The invention functions as follows:

[0054] At first, the optical measuring sections 5 are adjusted on the carrier 7 according to the theoretical dimensions and theoretical geometry of the tube 2 and of the thread 1. The manipulator 3 is moved into a base position.

[0055] Then, a produced tube is transferred into the holder and fixed. The industrial robot 6 then moves the carrier 7 with the measuring conduit 4 into coincidence over the thread 1 tube inwards (left direction in the view of FIG. 2).

[0056] During this process, tiltings about the adjusting axes S1, S2 are carried out and at the same time the images of the thread course taken by the telecentric lenses 5 are measured. The carrier 7 is aligned here in such a manner in space that an extremum of an optical width of the thread course is adjusted (see also the previous explanation for FIG. 6). This aligns the thread axis A and the main direction H of the carrier parallel to one another in the direction of the measuring.

[0057] The industrial robot 6 is subsequently stopped and only the carrier 7 is moved over its linear guiding. The measuring of the thread is carried out here. During the measuring the arrangement of one or more measuring conduits 4, 8 and of the first or also of the second light-section sensors 9, 10 are used. The measuring takes place advantageously and for achieving a rapid entire process while the measuring conduit 4 is again moved tube outwards again relative to the tube 2 (right direction in the view of FIG. 2).

[0058] According to the preferred exemplary embodiment no mechanical contact is made by the measuring apparatus for the measuring of the thread 1. A movement or rotation of the tube 2 does not take place during the entire measuring.

LIST OF REFERENCE NUMERALS

[0059] 1 thread to be measured [0060] 1a thread course [0061] 2 tube [0062] 3 manipulator [0063] 4 measuring conduit [0064] 5 optical measuring section [0065] 5a optical sensor [0066] 5b illumination [0067] 6 industrial robot [0068] 6a segments of the industrial robot [0069] 6b articulations of the industrial robot [0070] 7 carrier [0071] 8 second measuring conduit [0072] 9 first light-section sensor [0073] 10 second light-section sensor [0074] A thread axis [0075] S1 first adjusting axis [0076] S2 second adjusting axis [0077] H main direction