Position measuring device

Abstract

To provide a position measurement device that has a simple and inexpensive constitution and enables accurate position measurement.SOLUTION: A device includes one carrier (10), one scale (12) arranged on the carrier (10), and a plurality of fixing elements (16) for fixing the scale (12) to the carrier (10). The scale (12) extends in a longitudinal direction (X). The scale (12) has a measuring graduation (14) for position measurement at least in the longitudinal direction (X). The carrier (10) has a plurality of individual portions (10.1 to 10.7). The fixing elements (16) are arranged on the individual portions (10.1 to 10.7) of the carrier (10).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The invention relates to a device as claimed in the preamble of claim 1. [Background technology]

[0002] WO 2006 / 133753 discloses an apparatus for position measurement with a support and multiple fixing elements arranged along the scale on either side of the scale, with a solid joint respectively arranged between the support and the fixing elements, which connects the fixing elements, and thus the scale, to the support in a displaceable manner in the measuring direction X.

[0003] A disadvantage of the known measuring device is that the support is constructed in one piece. On the one hand, this has the consequence that the manufacture of the support or the measuring device is relatively costly. On the other hand, the realization of thermal decoupling between the support (or the measuring device) and the substrate (e.g. the machine bed) is relatively complicated, since this typically requires constructional measures, for example the use of additional solid joints. Thermal decoupling is also a prerequisite for high accuracy of the position measurement. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2006 / 133753 Brochure Summary of the Invention [Problem to be solved by the invention]

[0005] The problem underlying the invention is to provide an apparatus for position measurement which has a simple and inexpensive construction and allows for accurate position measurement. [Means for solving the problem]

[0006] This problem is solved according to the invention by a device with the features of claim 1.

[0007] The device formed according to the invention comprises a carrier, a scale arranged on the carrier and a number of fixing elements for fixing the scale to the carrier, the scale extending in a longitudinal direction, the scale comprising measuring graduations for at least a longitudinal position measurement, the carrier comprising a number of individual portions, the fixing elements being arranged on the individual portions of the carrier.

[0008] Preferably, the individual parts of the carrier are each attached to one fixing element or to a pair of fixing elements arranged opposite each other in a transverse direction extending perpendicular to the longitudinal direction of a plurality of fixing elements.

[0009] It is advantageous if the individual parts of the carrier are arranged separately from one another in the longitudinal direction.

[0010] Furthermore, it is advantageous if the individual parts of the carrier are distributed in the longitudinal direction, for example evenly spaced.

[0011] Alternatively, the individual parts of the carrier may be non-equidistantly spaced, for example the spacing between the individual parts of the carrier in the vicinity of the fixed point (i.e. the stationary fixed location of the scale) being greater than the spacing between the individual parts of the carrier at either free end of the scale.

[0012] The fixing element preferably comprises a number of solid joints for (local) thermal decoupling between the carrier and the scale.

[0013] For the stationary fixing of the scale relative to the carrier, fixing elements in the form of adhesive beads can be provided.

[0014] The individual portions of the carrier may also be referred to as discrete plates.

[0015] The measuring graduation is preferably used for position measurement in the longitudinal direction (i.e. the degree of freedom X) and in the transverse direction (i.e. the degree of freedom Y). Alternatively, the measuring graduation can be configured such that (in conjunction with a corresponding scanning unit) position measurement in six degrees of freedom (i.e. the degrees of freedom X, Y, Z, RX, RY, RZ) is possible.

[0016] The measuring graduation is, for example, an incremental graduation. Alternatively, the measuring graduation can be an absolute graduation, for example formed as a pseudorandom code.

[0017] According to the invention, a high reproducibility of the straightness of the scale is achieved. This is particularly advantageous if the scale comprises measuring graduations for longitudinal and transverse position measurements. For this purpose, the measuring graduation comprises a number of graduation structures which are periodically arranged along a first measuring direction (main measuring direction or X-direction) and a number of graduation structures which are periodically arranged along a second measuring direction (Y-direction). The first measuring direction and the second measuring direction run perpendicular to one another. The graduation structures in particular each have graduation lines.

[0018] Advantageous configurations of the invention are set forth in the dependent claims.

[0019] Further details and advantages of the device according to the invention will emerge from the following description of an embodiment with the aid of the attached drawings. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 shows a perspective view of an apparatus formed according to the invention, comprising a carrier, a scale arranged on the carrier and a number of fastening elements; [Diagram 2] Plan view of the device according to FIG. [Figure 3a] FIG. 1 shows a perspective view of individual parts of a carrier with a first and a second fastening element [Figure 3b] Plan view of the individual parts of the carrier according to FIG. 3a [Figure 4a] FIG. 13 is a perspective view of another individual part of the carrier with the third and fourth fastening elements [Figure 4b] Plan view of another individual part of the carrier according to FIG. 4a

DETAILED DESCRIPTION OF THE INVENTION

[0021] The same element or functionally identical elements are provided with the same reference numerals in each figure.

[0022] One embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The device formed according to the present invention has one carrier 10, a scale 12 arranged on the carrier 10, and a plurality of fixing elements 16. The scale 12 extends in the longitudinal direction (main measurement direction) X and includes a measurement scale 14 arranged in the measurement scale plane (i.e., the X / Y plane). The measurement scale 14 is formed as a photoelectrically scannable incremental scale for highly accurate position measurement in a second transverse direction Y that extends perpendicular to the longitudinal direction X in addition to the longitudinal direction. The scale 12 preferably has a negligibly small coefficient of thermal expansion, particularly less than 1.5×10 -6 K -1 below, but particularly less than 0.1×10 -6 K -1 and is made of a material having a coefficient of thermal expansion α. Such materials are glass or glass ceramics (e.g., Zerodur®) or metals such as Invar®.

[0023] The carrier 10 is preferably made of steel having a coefficient of thermal expansion of about 10.5×10 -6 K -1 .

[0024] The carrier 10 includes a plurality of individual plate-like parts 10.1 to 10.7. The scale 12 has a rectangular cross-section with two opposing side surfaces 18.1, 18.2 each extending in the longitudinal direction X (see FIG. 2).

[0025] The fixing elements 16 are used to fix the scale 12 to the carrier 10. The fixing elements 16 have a first group of fixing elements 16.11-16.71 and a second group of fixing elements 16.12-16.72. The fixing elements 16.11-16.71 and 16.12-16.72 are arranged on opposite sides 18.1, 18.2 of the scale 12 (see FIG. 2). As shown in FIG. 1, the fixing elements 16 are arranged on the individual parts 10.1-10.7 of the carrier 10.

[0026] The device shown in Fig. 1 is arranged on a base 1 (e.g. a machine bed). To fasten the device to the base 1, a screw 2 is provided. The screw 2 extends into the base 1 via the individual parts 10.1 to 10.7. The base 1 consists, for example, of granite.

[0027] The device according to the invention allows the realization of a support (i.e. carrier 10) that is made up of multiple components. The multiple-component design is advantageous in that the support and thus the device are relatively inexpensive to manufacture compared to the one-component design according to the prior art. Furthermore, the multiple-component design has the advantage that the thermal decoupling between the carrier 10 and the substrate 1 can be easily achieved. In this case, in particular, additional constructional measures, such as the use of separate solid joints, can be dispensed with.

[0028] It is advantageous that the individual parts (discrete plates) 10.1 to 10.7 of the carrier 10 are relatively small and can, so to speak, be moved locally (i.e. locally at the respective X-position) simply together with the substrate 1. As a result, in contrast to the prior art, the just-mentioned thermal decoupling can be achieved without the use of additional constructional measures.

[0029] Between the individual parts 10.1-10.7 of the carrier 10, further parts 11.1-11.6 of the carrier 10 (so-called intermediate parts) are arranged. The intermediate parts 11.1-11.6 are fixed to the base 1 by means of screws 4 and are used to support the scale 12 in the height direction (i.e. in the Z direction). For this purpose, the intermediate parts 11.1-11.6 are formed to immovably support the scale 12 on the carrier 10 in an intermediate position, i.e. in a position between the individual parts 10.1-10.7 of the carrier 10, respectively, via fastening means, and thus immovably connect it to the base 1. The intermediate parts 11.1-11.6 can also be omitted.

[0030] 1, each of the portions 10.1 to 10.7 of the carrier 10 is attached to a pair of fixing elements 16.11, 16.12 to 16.71, 16.72 arranged to face each other in the lateral direction Y among the plurality of fixing elements 16. In particular, the fixing elements 16.11, 16.12 to 16.71, 16.72 arranged in pairs are arranged on each of the portions 10.1 to 10.7 of the carrier 10 attached to these fixing elements, respectively.

[0031] Alternatively, each of the portions 10.1-10.7 of the carrier 10 may be attached to only one of the fixing elements 16 (eg 16.11-16.71 or 16.12-16.72).

[0032] 1, the individual parts 10.1-10.7 of the carrier 10 are arranged separately from one another in the longitudinal direction X. Furthermore, the individual parts 10.1-10.7 of the carrier 10 are distributed, in particular equally spaced, in the longitudinal direction X. In this case, the distance between the individual parts 10.1-10.7 of the carrier 10 is, for example, 100 mm each.

[0033] The fixing element 16 shown in FIG. 1The scale 12 has a first fixing element 16.11 arranged on a side 18.1 of the scale 12 and a second fixing element 16.12 arranged on a second side 18.2 of the scale 12. The first fixing element 16.11 and the second fixing element 16.12 are arranged to face each other in the lateral direction Y. The following description also applies to the fixing elements 16.21, 16.22 to 16.71, 16.72 (excluding 16.41, 16.42) arranged in pairs.

[0034] The first fixing element 16.11 is formed for supporting the scale 12 in a position P1 (see FIG. 3b) so that it is freely movable relative to the carrier 10 in the longitudinal direction X. Furthermore, the first fixing element 16.11 is formed for supporting the scale 12 immovably on the carrier 10 in the transverse direction Y. For this purpose, the first fixing element 16.11 is formed in particular as a solid joint.

[0035] With reference to Fig. 3, the first fastening element 16.11 has a first part 20.1 fixed by a material bond to the first side 18.1 of the scale 12. Furthermore, the first fastening element 16.11 has a second part 20.2 (see Figs. 3a and 3b) fixed by a material bond to the upper side 22 of the part 10.1 attached to the first fastening element 16.11 of the respective part 10.1-10.7 of the carrier 10. The material bond is in particular an adhesive bond.

[0036] The second fixing element 16.12 is formed for supporting the scale 12 in a first position P1 in a freely movable manner relative to the carrier 10 in the longitudinal direction X. Furthermore, the second fixing element 16.12 is formed for supporting the scale 12 immovably on the carrier 10 in the transverse direction Y. For this purpose, the second fixing element 16.12 is formed in particular as a solid joint.

[0037] The second fastening element is connected to the scale 12 and to the part 10.1 of the carrier 10 in the same way as the first fastening element 16.11.

[0038] With reference to Fig. 3a, the device comprises a first fastening means 24.1 for fastening the scale 12 to the carrier 10. The first fastening means 24.1 is arranged on the one hand on the upper surface 22 of the part 10.1 of the carrier 10 and on the other hand on the first fastening element 16.11 and the second fastening element 16. 12 The first fastening means 24.1 is formed in strip form and extends substantially in the transverse direction Y. For example, the first fastening means 24.1 comprises a double-sided adhesive tape, in particular a transfer adhesive tape.

[0039] The first fastening means 24.1 are arranged accordingly on each of the parts 10.1 to 10.7 (except 10.4) of the carrier 10.

[0040] In addition, the fixing element 16 shown in Fig. 1 comprises a third fixing element 16.41 arranged on a first side 18.1 of the scale 12 and a fourth fixing element 16.42 arranged on a second side 18.2 of the scale 12. The third fixing element 16.41 and the fourth fixing element 16.42 are arranged opposite each other in the lateral direction Y. The fixing elements 16.41, 16.42 arranged in pairs are fixed to the carrier 10. 10 Attached or located at .4.

[0041] The third fixing element 16.41 is formed for immovably supporting the scale 12 on the carrier 10 in the longitudinal direction X and the transverse direction Y at a second position P2 (see FIG. 4b) different from the first position P1. The fourth fixing element 16.42 is formed for immovably supporting the scale 12 on the carrier 10 in the longitudinal direction X and the transverse direction Y at the second position P2. For example, the third fixing element 16.41 and the fourth fixing element 16.42 each comprise one adhesive bead, in particular a fillet weld, for connecting the part 10.4 of the carrier 10 and the scale 12.

[0042] In addition, with reference to FIG. 4a, the apparatus includes second fastening means 24 for fastening the scale 12 to the carrier 10. 2and the third fastening means 24.3. The second fastening means 24.2 and the third fastening means 24.3 are arranged on the one hand on the upper surface of the part 10.4 of the carrier 10 and on the other hand between the third fastening element 16.41 and the fourth fastening element 16.42. The second fastening means 24.2 and the third fastening means 24.3 are each formed in a strip and extend substantially in the longitudinal direction X. For example, the second fastening means 24.2 and the third fastening means 24.3 each comprise a strip of double-sided adhesive tape, in particular a transfer adhesive tape.

[0043] The first to third fastening means 24.1 to 24.3 are used to assist the fastening of the scale 12 by the first to fourth fastening elements 16.11, 16.12, 16.41, 16.42, whereby a particularly stable and reliable construction of the device is achieved.

[0044] Furthermore, the first to third fastening means 24.1 to 24.3 are used to detach the scale 12 from the carrier 10 to prevent the effects of friction (or to generate limited shear forces).

[0045] For example, the first to third fastening means 24.1 to 24.3 each comprise a strip of double-sided adhesive tape with a width of 10 mm.

[0046] Instead of the transfer adhesive tape mentioned above, a very soft adhesive with balls mixed in or a liquid transfer adhesive can also be used.

[0047] The third and fourth fixing elements 16.41, 16.42 can alternatively be formed in such a way that they support or connect the scale 12 to the carrier 10 in the second position P2 immovably in the longitudinal direction X but flexibly in the transverse direction Y. Such a connection is disclosed in particular in EP 3 026 389 A1.

[0048] An advantage of the present invention is that the scale 12 is connected to the base body 1 by the fixing elements 16 without significant lateral movements and scale deflections even under the action of lateral forces in the Y direction (e.g. lateral accelerations). This is particularly advantageous in the case of dimension graduations 14 for position measurements in the longitudinal direction (X degree of freedom) and lateral direction (Y degree of freedom).

[0049] base The body 1 preferably consists of a material with a thermal expansion coefficient smaller than that of the carrier 10 .

[0050] The invention is not limited to the photoelectric scanning principle: the measuring graduation 14 can in particular also be designed to be magnetically or inductively operable. In addition, the present application relates to the invention described in the claims, but may also include the following as other aspects. 1. An apparatus comprising a carrier (10), a scale (12) arranged on the carrier (10) and a number of fixing elements (16) for fixing the scale (12) to the carrier (10), the scale (12) extending in a longitudinal direction (X) and the scale (12) comprising measuring graduations (14) for at least position measurement in the longitudinal direction (X), An apparatus, characterized in that the carrier (10) comprises a plurality of individual parts (10.1-10.7) and that the fixing elements (16) are arranged on the individual parts (10.1-10.7) of the carrier (10). 2. The device according to claim 1, characterized in that each of the parts (10.1 to 10.7) of the carrier (10) is attached to one fixing element or to a pair of fixing elements (16.11, 16.12 to 16.71, 16.72) of a plurality of fixing elements (16) arranged opposite each other in a transverse direction (Y) extending perpendicular to the longitudinal direction (X). 3. 3. The device according to claim 1 or 2, characterized in that the individual parts (10.1 to 10.7) of the carrier (10) are arranged separately from one another in the longitudinal direction (X). 4. 4. The device according to any one of claims 1 to 3, characterized in that the individual parts (10.1 to 10.7) of the carrier (10) are distributed in the longitudinal direction (X), in particular at equal intervals. 5. 5. The device according to any one of claims 1 to 4, characterized in that the fixing element (16) comprises at least one first fixing element (16.11) arranged on a first side (18.1) extending in the longitudinal direction (X) of the scale (12). 6. 6. The device according to claim 5, characterized in that the first fixing element (16.11) is formed for supporting the scale (12) in a freely movable manner relative to the carrier (10) in the longitudinal direction (X) in the first position (P1). 7. 7. The device according to claim 5 or 6, characterized in that the first fixing element (16.11) is formed to support the scale (12) immovably on the carrier (10) in a transverse direction (Y) extending perpendicular to the longitudinal direction (X). 8. 8. The device according to any one of claims 5 to 7, characterized in that the first fixing element (16.11) has a first part (20.1) fixed to the first side (18.1) of the scale (12) by a material bond. 9. 9. The device according to any one of claims 5 to 8, characterized in that the first fixing element (16.11) has a second part (20.2) which is fixed to the upper surface (22) of one part (10.1) of the individual parts (10.1 to 10.7) of the carrier (10) by a material bond. 10. 10. The device according to claim 8 or 9, wherein the physical bond is an adhesive bond. 11. The device according to any one of claims 5 to 10, characterized in that the fixing element (16) comprises a second fixing element (16.12) arranged on a second side (18.2) extending in a longitudinal direction (X) of the scale (12), and the first fixing element (16.11) and the second fixing element (16.12) are arranged opposite each other in a transverse direction (Y) extending perpendicular to the longitudinal direction (X). 12. 12. The device according to claim 11, characterized in that the first fixing element (16.11) and the second fixing element (16.12) each comprise one solid joint. 13. 13. Apparatus according to claim 11 or 12, characterized in that the apparatus comprises at least one first fastening means (24.1) for fastening the scale (12) to the carrier (10), the first fastening means (24.1) being arranged between the first fastening element (16.11) and the second fastening element (16.12) on the upper surface (22) of the part (10.1) attached to the first fastening element (16.11) and the second fastening element (16.12) of the respective part (10.1-10.7) of the carrier (10). 14. 14. Apparatus according to claim 13, characterised in that the first fastening means (24.1) are strip-shaped and extend in a transverse direction (Y) extending substantially perpendicular to the longitudinal direction (X). 15. The device according to any one of claims 6 to 14, characterized in that the fixing element (16) comprises at least one third fixing element (16.41) arranged on a first side (18.1) of the scale (12), the third fixing element (16.41) being formed to immobilize the scale (12) on the carrier (10) in a longitudinal direction (X) and in a transverse direction (Y) extending perpendicular to the longitudinal direction (X) at a second position (P2) different from the first position (P1).

Claims

1. An apparatus comprising a carrier (10), a scale (12) arranged on the carrier (10) and a number of fixing elements (16) for fixing the scale (12) to the carrier (10), the scale (12) extending in a longitudinal direction (X) and the scale (12) comprising measuring graduations (14) for at least a position measurement in the longitudinal direction (X), The device is characterized in that the carrier (10) is made up of a plurality of individual parts (10.1-10.7) distributed and arranged in the longitudinal direction (X), that fixing elements (16) are arranged on the individual parts (10.1-10.7) of the carrier (10), and that, in order to support a scale (12) in the height direction, between the individual parts (10.1-10.7) of the carrier (10), further or intermediate parts (11.1-11.6) of the carrier (10) formed to the same size as the individual parts (10.1-10.7) of the carrier (10) and not having fixing elements (16) can be arranged at intervals in the longitudinal direction (X) that are greater than the length of the individual parts of the carrier (10) or the further or intermediate parts (11.1-11.6) of the carrier (10).

2. 2. The device according to claim 1, characterized in that the individual parts (10.1 to 10.7) of the carrier (10) are respectively attached to one fixing element or to a pair of fixing elements (16.11, 16.12 to 16.71, 16.72) of a plurality of fixing elements (16) arranged opposite each other in a transverse direction (Y) extending perpendicularly to the longitudinal direction (X).

3. 3. Apparatus according to claim 1 or 2, characterised in that the individual parts (10.1-10.7) of the carrier (10) are equally spaced in the longitudinal direction (X).

4. 4. The device according to claim 1, wherein the fixing element (16) comprises at least one first fixing element (16.11) arranged on a first side (18.1) extending in the longitudinal direction (X) of the scale (12).

5. 5. The device according to claim 4, characterized in that the first fixing element (16.11) is formed for supporting the scale (12) in a freely movable manner relative to the carrier (10) in the longitudinal direction (X) in the first position (P1).

6. 6. An arrangement according to claim 4 or 5, characterized in that the first fixing element (16.11) is formed for supporting the scale (12) immovably on the carrier (10) in a transverse direction (Y) extending perpendicularly to the longitudinal direction (X).

7. 7. The device according to claim 4, wherein the first fixing element (16.11) has a first part (20.1) fixed to the first side (18.1) of the scale (12) by a material bond.

8. 8. The device according to claim 4, wherein the first fastening element (16.11) has a second part (20.2) which is fastened to the upper surface (22) of one of the individual parts (10.1-10.7) of the carrier (10) by a material bond.

9. 9. A device according to claim 7 or 8, characterised in that the material bond is an adhesive bond.

10. 10. The device according to claim 4, wherein the fixing element (16) comprises a second fixing element (16.12) arranged on a second side (18.2) extending in a longitudinal direction (X) of the scale (12), the first fixing element (16.11) and the second fixing element (16.12) being arranged opposite each other in a transverse direction (Y) extending perpendicular to the longitudinal direction (X).

11. 11. The device according to claim 10, characterized in that the first fastening element (16.11) and the second fastening element (16.12) are each formed as a solid joint.

12. 12. Apparatus according to claim 10 or 11, characterized in that the apparatus comprises at least one first fastening means (24.1) for fastening the scale (12) to the carrier (10), the first fastening means (24.1) being arranged between the first fastening element (16.11) and the second fastening element (16.12) on the upper surface (22) of the part (10.1) attached to the first fastening element (16.11) and the second fastening element (16.12) of the respective part (10.1-10.7) of the carrier (10).

13. 13. Apparatus according to claim 12, characterised in that the first fastening means (24.1) are strip-shaped and extend in a transverse direction (Y) extending substantially perpendicular to the longitudinal direction (X).

14. 14. The device according to claim 5, wherein the fixing element (16) comprises at least one third fixing element (16.41) arranged on a first side (18.1) of the scale (12), the third fixing element (16.41) being formed for immovably supporting the scale (12) on the carrier (10) in a second position (P2) different from the first position (P1) in a longitudinal direction (X) and in a transverse direction (Y) extending perpendicular to the longitudinal direction (X).

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