Arrangement for determining the relative position of two bodies that are movable in relation to each other, and process for producing such an arrangement

• US 20020129508A1
• Filed: 05/15/2002
• Published: 09/19/2002
• Est. Priority Date: 05/14/1999
• Status: Active Grant

• Current Assignee: Bruno Schnos, Herbert Kirchner, Peter Blattner
• Original Assignee: Bruno Schnos, Herbert Kirchner, Peter Blattner
• Inventors: Schnos, Bruno, Blattner, Peter, Kirchner, Herbert
• Granted Patent: US 6,564,468 B2
• Time in Patent Office: Days
• US Class Current: 33/706
• CPC Class Codes: F16C 29/005 Guide rails or tracks for a linear bearing, i.e. adapted for movement of a carriage or bearing body there along
• CPC Class Codes: F16C 29/0633 with a bearing body defining a U-shaped carriage, i.e. surrounding a guide rail or track on three sides
• CPC Class Codes: F16C 41/007 Encoders, e.g. parts with a plurality of alternating magnetic poles
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: G01D 5/2457 Incremental encoders having reference marks

Abstract

In an arrangement for determining the relative position of two bodies (3, 7) that are movable relative to each other, a separate measuring tape (29) is attached to a first (3) of the two bodies (3, 7). The measuring tape includes at least one track of measuring markings, distributed in the longitudinal direction of the tape. The second (7) of the two bodies (3, 7) carries a sensor arrangement (31) which responds to the measuring markings and travels along the track, in the course of relative movement between the two bodies (3, 7). The measuring tape (29) is attached to the first body (3), at at least two attachment points that are arranged at a distance from each other in the longitudinal direction of the tape, and is elastically stretched between the attachment points in the longitudinal direction of the tape.

Claims

1. An arrangement for determining the relative position of two bodies movable in relation to each other, comprising:

a first body;

a second body movable relative to the first body;

a separate measuring tape applied to the first body and having a longitudinal direction;

the measuring tape having at least one track of measuring markings which are distributed along the tape in said longitudinal direction;

a sensor carried by the second body for movement along the track of measuring markings in the course of relative movement between the two bodies, the sensor being responsive to the measuring markings; and

the measuring tape being attached to the first body at at least two attachment points, which attachments points are arranged at a distance from each other in the longitudinal direction of the tape, and being elastically stretched between the attachment points in the longitudinal direction of the tape.

2. An arrangement according to claim 1, wherein the measuring tape is attached to the first body solely at the opposite longitudinal ends of the tape.

3. An arrangement according to claim 1 or 2, wherein the elastic stretching of the measuring tape amounts to at least 30 μ

m per linear meter of the measuring tape.

4. An arrangement according to claim 1 or 2, wherein the elastic stretching of the measuring tape amounts to at least 50 μ

m per linear meter of the measuring tape.

5. An arrangement according to claim 1 or 2, wherein the elastic stretching of the measuring tape amounts to at least 70 μ

m to 100 μ

per linear meter of the measuring tape.

6. An arrangement according to claim 1, wherein the measuring tape is formed by a tape material drawn from a supply roll.

7. An arrangement according to claim 1, wherein the measuring tape is produced from a metallic material.

8. An arrangement according to claim 1, wherein the measuring tape comprises thin material zones or material breakthroughs which follow one another in the longitudinal direction of the tape, to form said measuring markings.

9. An arrangement according to claim 1, wherein the measuring markings comprise a group of markings which follow one another at regular distances in the longitudinal direction of the tape.

10. An arrangement according to claim 1, wherein the measuring markings comprise a group of reference markings which are designed and/or located on the measuring tape in a manner such that, without knowledge of the initial position of the second body relative to the first body, at least an approximate end position of the second body relative to the first body can be determined by sensing with said sensor a few consecutive reference markings.

11. An arrangement according to claim 8, wherein pairs of reference markings that are adjacent in the longitudinal direction of the tape are spaced apart from one another by distances which differ for at least a plurality of the pairs.

12. An arrangement according to one claim 1, wherein:

the first body is an elongated body having a longitudinal axis; and

the measuring tape is applied to the elongated body in the direction of said longitudinal axis.

13. An arrangement according to claim 12, wherein the first body comprises a guide rail of a linear-guide arrangement.

14. A process for the production of the arrangement according to claim 12, wherein:

a length of a material strand is cut at a cut-off point, in order to produce the elongated body;

the measuring tape extends over a section of the material strand which is longer than the length of the strand that is to be cut;

the measuring tape is first attached under elastic stretching to the material strand solely at attachment points associated with the longitudinally opposite tape ends;

the measuring tape is then attached to the material strand at additional attachment points which are close to the cut-off point, in the direction of the longitudinal axis, on both sides of the cut-off point; and

the material strand is thereafter cut, together with the measuring tape, between the attachment points that are close to the cut-off point.

15. A process according to claim 14, wherein the measuring tape is attached to the material strand at the attachment points by means of welding.

16. A process according to claim 14, wherein:

a measuring-tape cover, which is separate from the material strand and the measuring tape and which extends over the length of the material section of the material strand, is applied to the material strand before the strand is cut; and

the measuring-tape cover is cut at the cut-off point, together with the material strand and the measuring tape.

17. A process according to claim 16, wherein the measuring-tape cover is, before said cutting, attached to the material strand and/or the measuring tape.

18. A process according to claim 16, wherein the measuring-tape cover is attached to the material strand along the longitudinal edges of the cover tape which run in the direction of the longitudinal axis of the material strand.

19. A process according to claim 18, wherein the measuring-tape cover is attached to the material strand essentially in a continuous fashion.

20. An arrangement for determining the relative position of two bodies movable in relation to each other, comprising:

a first body, the first body carrying measuring markings which are distributed over a marking range;

a second body, the second body movable relative to the first body and carrying a sensor which responds to the measuring markings upon traveling thereover in the course of relative movement between the two bodies;

a cover tape which is separate from the first body and which covers the measuring markings, the cover tape having a flat side that is directed towards supporting surfaces on the first body, the cover tape being attached to the first body along each of the two longitudinally extending edges of the cover tape by at least one longitudinal welding seam; and

the longitudinal welding seams running at a distance, in the direction crosswise to the longitudinal direction of the tape, from the respectively adjacent longitudinal edge of the cover tape and forming, in the region of the supporting surfaces, a material fusing zone of the cover tape with the first body.

21. An arrangement according to claim 20, wherein:

the measuring markings are sunk into a relief-like depression of the first body, and

the cover tape is inserted into the relief-like depression.

22. An arrangement according to claim 21, wherein the cover tape is inserted in the relief-like depression in a manner such that the outer surface of the cover tape lies approximately flush with the adjacent surface regions of the first body.

23. An arrangement according to claim 21, wherein:

the relief-like depression comprises a stepped depression; and

the supporting surfaces for the cover tape are formed by a support-step arrangement of the depression.

24. An arrangement according to claim 20, wherein the cover tape is applied to the first body by means of laser welding.

25. An arrangement according to claim 20, wherein the measuring markings are arranged on a markings carrier which is separate from the first body and from the cover tape.

28. A process according to claim 27, wherein said longitudinal welding seams are applied in the same welding direction.

29. A process according to claim 28, wherein the longitudinal welding seams are applied jointly, starting from one lengthwise end of the cover tape.

30. A process according to claim 27, wherein the longitudinal welding seams are applied by means of a laser welding device with bifocal optics.

26. A process for the production of an arrangement for determining the relative position of two bodies which are movable in relation to each other, wherein a first of the two bodies carries measuring markings which are distributed over a marking range and the second of the two bodies carries a sensor arrangement which responds to the measuring marking and travels over the marking range in the course of relative movement between the two bodies, said process comprising:

covering the measuring markings by a cover tape which is separate from the first body and which is laid with a flat side thereof upon supporting surfaces of the first body; and

attaching the cover tape to the first body along each of the two longitudinal edges of the tape by means of at least one longitudinal welding seam, said longitudinal welding seams being applied at a distance, in the direction crosswise to the longitudinal direction of the tape, from the respectively adjacent longitudinal edge of the unwelded cover tape in a manner such that said seams cause a material fusing of the cover tape with the first body in the region of the supporting surfaces.

27. A process for the production-of an arrangement for the determination of the relative position of two bodies that are movable in relation to each other, wherein a first of the two bodies carries measuring markings that are distributed over a marking range and the second of the two bodies carries a sensor arrangement which responds to the measuring marking and travels over the marking range in the course of relative movement between the two bodies, said process comprising:

covering the measuring markings by a cover tape which is separate from the first body; and

attaching the cover tape to the first body along each of the longitudinal edges of the cover tape by at least one longitudinal welding seam adjacent to the respective longitudinal edges of the cover tape, said two longitudinal welding seams being applied essentially simultaneously.

31. A process for the application of a measuring tape to a separate carrier, comprising attaching the measuring tape to the carrier at at least two attachment points which are arranged at a distance from each other in the longitudinal direction of the tape, the measuring tape being under elastic stretching between the attachment points.