GB1583489A

GB1583489A - Length-measuring devices

Info

Publication number: GB1583489A
Application number: GB2881277A
Authority: GB
Original assignee: Dr Johannes Heidenhain GmbH
Current assignee: Dr Johannes Heidenhain GmbH
Priority date: 1976-07-09
Filing date: 1977-07-08
Publication date: 1981-01-28
Also published as: DE2630880B2; CH606989A5; ATA488377A; DE2630880A1; FR2357862A2; FR2357862B2; IT1117678B; AT381793B; DE2630880C3; JPS539141A

Description

(54) IMPROVEMENTS IN LENGTH-MEASURING DEVICES (71) We, DR. JOHANNES HEIDENHAIN GMBH, a joint stock company organised under the laws of the Federal Republic of Germany, of Postfach 1260, D-8225 Traunreut, Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a lengthmeasuring device for use in measuring or adjusting the relative position of two objects, in which a measuring scale and a scanning unit are, for screening from environmental influences, accommodated in an elongate hollow body which is resistant to bending, the scale being secured within the hollow body.Such a length-measuring device in which the hollow body is fixed to one of the said two objects by means of parts formed like joints is the subject of Patent Specification No. 1536364.

The present invention has for its object the possibility of a further advantageous fixing for such a length-measuring device.

In the specific example described in Patent Specification No. 1536364, the said parts are provided at the ends of the hollow body and are angular parts which have a weak place in the form of a groove. However, according to the present invention, the hollow body is fixed to one of the two objects by means of joints having curved surfaces as bearing surfaces of the joints.

Preferably these points are ball-and-socket joints. The provision of such joints affords a number of advantages: 1. The fixing of the scale is free from constraining force, i.e. the hollow body and hence the scale are not subject to any bending, even if the fitting-surfaces are uneven, 2. Robust fixing to the machine, 3. Simple mounting, 4. The joints are easily manufactured, 5. Space-saving constructional method.

Several examples of embodiment of the invention will now be described with reference to the accompanying drawings, in which: Fig. 1 is a plan view of a first lengthmeasuring device embodying the invention, Fig. 2 is a sectional view taken on the line II-II of Fig. 1, Fig. 3 is a plan view of a second embodiment of the invention, Fig. 4 is a sectional view taken on the line TV-IV of Fig. 3, Fig. 5 is a sectional view taken on the line V-V of Fig. 3, Fig. 6 is al plan view of a third embodiment of the invention, Fig. 7 is a sectional view taken on the line VI-VI of Fig. 6, Fig. 8 is a sectional view taken on the line VII-VII of Fig. 6.

Figs. 1, 3 and 6 show enclosed incremental length-measuring devices. Lengthmeasuring devices of this kind are subject matter of German Utility Model 7,504,024.

In this measuring device the scale and scanning components are, for screening from environmental influences, enclosed in an elongated hollow body 1 which is resistant to bending. The hollow body 1 is closed by means of sealing lips through which there projects a driver 2 for the scanning unit carried on the scale. The driver 2 is formed on a component 3 fixed to one of the objects, for example a machine table.

The ends of the hollow body 1 are closed by means of holders 4. Fixing of the hollow body 1 to one of the objects, for example a machine bed 9 is effected by means of balland-socket joints 5. In this preferred embodiment, the ball-and-socket joints 5 in each case incorporate a sphere segment 6 tiltably mounted on the holder 4. The balland-socket joints 5 permit robust fixing as well as rapid fitting of the measuring device on the machine without constraining forces arising. Fixing of the hollow body 1 to the fitting surface is effected by means of screws 7.

In Fig. 1, the hollow body 1 is mounted with the interposition of one ball-andsocket joint 5 respectively at each end.

Figs. 3, 4 and 5 show an embodiment having altogether three ball-and-socket joints 5 in the manner of a three-point support.

Figs. 6, 7 and 8 show a further possibility, in which at one end of the hollow body 1 two fixedly mounted balls 8 are provided which are in line with one another transversely of the measuring direction, and at the opposite end of the hollow body 1 a symmetrically arranged ball-and-socket joint 5 is provided, so that a three-point support is provided.

In the scope of the invention other modifications are, of course, conceivable. Thus, for example, it is also possible to replace the sphere segments by cylinder segments.

WHAT WE CLAIM IS: 1. A length-measuring device for use in measuring or adjusting the relative position of two objects, in which a measuring scale and a scanning unit are, for screening from environmental factors, accommodated in an elongated hollow body, which is resistant to bending, the scale being secured within the hollow body, wherein the hollow body is fixed to one of the said two objects by means of joints having curved surfaces as bearing surfaces of the joints.

2. A length-measuring device according to claim 1, wherein the said joints are balland-socket joints each of which include a spherical segment which is tiltably mounted with respect to the socket of the joint.

3. A length-measuring device according to claim 2, wherein the said joints comprise at least one ball-and-socket joint provided at each end of the hollow body.

4. A length measuring device according to claim 2, wherein the ball-and-socket joints are provided on the hollow body in the manner of a three-point support.

5. A length measuring device according to claim 1, wherein at one end of the hollow body there are two of the said joints each of which two joints includes a ball and the two balls being in line with one another transversely of the measuring direction, and at the other end of the hollow body there is a third one of the said joints, the third joint being a ball-andsocket joint which is symmetrically disposed in relation to the said two balls.

6. A length-measuring device substantially as described hereinbefore with reference to Figs. 1 and 2, or to Figs. 3, 4 and 5, or to Figs. 6, 7 and 8 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. support. Figs. 6, 7 and 8 show a further possibility, in which at one end of the hollow body 1 two fixedly mounted balls 8 are provided which are in line with one another transversely of the measuring direction, and at the opposite end of the hollow body 1 a symmetrically arranged ball-and-socket joint 5 is provided, so that a three-point support is provided. In the scope of the invention other modifications are, of course, conceivable. Thus, for example, it is also possible to replace the sphere segments by cylinder segments. WHAT WE CLAIM IS:

1. A length-measuring device for use in measuring or adjusting the relative position of two objects, in which a measuring scale and a scanning unit are, for screening from environmental factors, accommodated in an elongated hollow body, which is resistant to bending, the scale being secured within the hollow body, wherein the hollow body is fixed to one of the said two objects by means of joints having curved surfaces as bearing surfaces of the joints.