Length sensor

• US 20040154178A1
• Filed: 04/26/2004
• Published: 08/12/2004
• Est. Priority Date: 04/11/2001
• Status: Active Grant

• Current Assignee: Dr. Johannes Heidenhain GmbH
• Original Assignee: Dr. Johannes Heidenhain GmbH
• Inventors: Boge, Ludwig, Herkt, Peter
• Granted Patent: US 7,121,013 B2
• Time in Patent Office: Days
• US Class Current: 33/559
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01B 3/002 Details
• CPC Class Codes: G01B 3/008 Arrangements for controlling the measuring force
• CPC Class Codes: G01B 3/22 Feeler-pin gauges, e.g. dial gauges for measuring contours or curvatures G01B5/20

Abstract

A length measuring probe that includes a base body, a guide element and a probe pin having a touch scanning element for touch scanning a measuring object, the probe pin is seated, displaceable in relation to the base body in a measuring direction opposite a spring force F via the guide element. A detection device detects a position of the probe pin with respect to the base body and a first spring element and a second spring element arranged behind the first spring element in the measuring direction so as to prestress the probe pin. The guide element is arranged between the first and second spring elements, on which facing end areas of the first and second spring elements are fixed in place, and wherein the at least one guide element is seated, displaceable in the measuring direction, on the probe pin and on the base body.

The invention relates to a length sensor with a relatively large measuring zone, that is with a large lift of the stylus (2), wherein a plurality of helical springs (7, 8) are arranged one behind the other in order to pretension the stylus (2). A ball bearing arrangement (4) is interposed between two helical springs (7, 8) and bears the stylus (2) in such a manner that it can be displaced in the longitudinal direction X and is mounted itself on the base (1) so as to be displaceable in the longitudinal direction X.

Claims

1. A length measuring probe, having

a probe pin (2) with a touch scanning element (6) for touch scanning a measuring object (5), which is seated, displaceable in relation to a base body (1) in the measuring direction X opposite a spring force F, by means of at least one guide element (4),

a detection device (9) for detecting the position of the probe pin (2) with respect to the base body (1), characterized in that

the probe pin (2) is prestressed by several spring elements (7, 8) arranged one behind the other in the measuring direction X,

a guide element (4) is arranged between respectively two spring elements (7, 8), on which the facing end areas of these two spring elements (7, 8) are fixed in place, wherein the guide element (4) is seated, displaceable in the measuring direction X, on the probe pin (2) and on the base body (1).

2. The length measuring probe in accordance with claim 1, characterized in that the probe pin (2) is prestressed by means of two spring elements (7, 8), wherein an end area of one of the spring elements (7) is fixed in place on the probe pin (2), and the other end area of this spring element (7) is fixed in place on the guide element (4), and an end area of the further spring element (8) is fixed in place on the guide element (4), and the other end area of this spring element (8) on the base body (1).

3. The length measuring probe in accordance with one of the preceding claims, characterized in that the guide element is a ball bearing guide (4).

4. The length measuring probe in accordance with claim 3, characterized in that the ball bearing guide (4) consists of a ball bearing cage (41) and balls (42) rotatably seated in it, and that the end areas of the spring elements (7, 8) are fixed in place on the ball bearing cage (41) of the ball bearing (4).

5. The length measuring probe in accordance with one of the preceding claims, characterized in that the probe pin (2) is seated, displaceable in the measuring direction X, by at least one further guide element (3) on the base body (1), on which none of the spring elements (7, 8) have been fixed in place.

6. The length measuring probe in accordance with claim 5, characterized in that the further guide element is a ball bearing guide (3) between the probe pin (2) and the base body (1).

7. The length measuring probe in accordance with claim 5, characterized in that the further guide element (3) is rigidly fixed in place on the base body (1).

8. The length measuring probe in accordance with one of the preceding claims, characterized in that the spring elements are helical springs in the form of compression springs (7, 8).

9. The length measuring probe in accordance with one of claims 1 to 7, characterized in that the spring elements are helical springs in the form of tension springs (10).

10. The length measuring probe in accordance with one of the preceding claims, characterized in that the spring elements (7, 8) have the same spring properties, so that the guide element (4) is maintained centered between the spring elements (7, 8).