Geometrical instruments – Distance measuring – Error compensation
Reexamination Certificate
1999-05-05
2003-03-18
Gutierrez, Diego (Department: 2859)
Geometrical instruments
Distance measuring
Error compensation
C033S503000, C374S141000
Reexamination Certificate
active
06532680
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a flat sensor for measuring temperature and/or expansion, to a special adaptation case for a sensor, to a use of a sensor, to an arrangement for compensating for thermal deformations using sensors, as well as to a method for performing the compensation.
RELATED TECHNOLOGY
European Patent No. EP 349 783 B1 discloses determining machine-tool temperatures in order to define their temperature-dependent expansion and to compensate therefor. The entire temperature variation over the expanding machine part is determined, in this context, for the temperature-dependent expansion. For this, one uses a resistor which extends in the direction of expansion of the machine part and features an intensive thermal contact with the machine part. The resistor used produces an output signal that is proportional to the average temperature and, thus, to the total expansion. For the contacting, suitable contact elements are provided at both ends of the resistor.
Here the drawback is that a separate resistor is needed for each required length. In addition, interference effects, such as deterioration due to ageing, which influence resistance and corrupt the measuring result, are not compensated.
The article,“Temperatureinflüsse auf die Werkzeugmaschinen-Genauigkeit” (The Effects of Temperature on Machine Tool Accuracy) by Reto Gruber and Wolfgang Knapp, published in “Werkstatt und Betrieb” (Workshop and Operation), edition 131 (1998) 11, discloses that the warming of a machine tool results in deformations and, thus, in inaccuracies. Therefore, the new ISO/DIS 230-3 testing standard provides for determining thermal deformations in a machine tool to assess its accuracy. A warming of this kind essentially takes place during machine tool operation, in which, in particular, the spindle's stationary mount heats up, the result being that the heat is conducted from there into the entire machine tool.
The above mentioned article merely discusses the problem and the test provided in ISO/DIS 230-3 for qualitatively determining thermal deformations.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a sensor which avoids the mentioned disadvantages, and which can be used universally and produced cost-effectively. In addition, an aim is to provide a simple method for individually adapting the sensor to specific circumstances. Moreover, the present invention can provide a sensor arrangement for detecting a temperature distribution which causes a deformation in the machine tool, preferably using a minimum number of sensors. This arrangement should be able to be used universally and produced cost-effectively. In addition, the intention is to delineate a simple method for compensating for thermal deformations by utilizing the output signals from the arrangement.
The present invention provides a flat sensor for measuring temperature and/or expansion, in particular of a machine part, or of a length-measuring device or of an angular-position measuring device, comprising at least one structural component (ST
1
, ST
2
, ST
3
) having temperature-dependent electrical conductivity, the structural components (ST
1
, ST
2
, ST
3
) being uniformly distributed over the entire length of the sensor (S). The sensor is characterized in that at least two tracks (SP
1
, SP
2
, SP
3
, SP
4
, SP
5
, SP
6
), which include interconnected structural components (ST
1
, ST
2
, ST
3
), are provided.
Advantageous further features of the sensor may include that: (a) the structural components (ST
3
) of a track (SP
5
, SP
6
) are connected in series; (b) between the two structural components (ST
3
) is an electrical connection element (VE), which can be used to interconnect the two tracks (SP
5
, SP
6
); (c) a soldered point (LP) is provided as an electrical connection element (VE) for the two tracks; (d) the structural components (ST
1
, ST
2
) of one track (SP
1
, SP
2
, SP
3
, SP
4
) are connected in parallel; (e) the at least two tracks (SP
1
, SP
2
, SP
3
, SP
4
) are made up of at least two different materials; (f) an adhesive layer (KS) is provided on the rear side of the sensor (S) for adhesively mounting it on a component part to be measured, and that the adhesive layer (KS) is especially thermally conductive; (g) a protective layer is adhesively applied to the front side of the sensor (S) in its mounted state, protecting the sensor (S) from damage; (h) the sensor (S) contains electronic modules (V, AW); (i) the electronic modules contain an amplifier circuit (V); (j) the electronic modules contain an evaluation circuit (AW); (k) the sensor (S) has four tracks (SP
1
, SP
2
, SP
3
, SP
4
), the structural components (ST
1
) of the two tracks (SP
1
, SP
4
) being manufactured from a first material, and the structural components (ST
2
) of the two tracks (SP
2
, SP
3
) from a second material; and/or (
1
) the four tracks (SP
1
, SP
2
, SP
3
, SP
4
) in the evaluation circuit (AW) are interconnected into a bridge.
The present invention also provides a method for individually adapting a flat sensor, characterized in that a length of the sensor (S) that is no longer needed is cut along a trim line (SL) at the end of the sensor (S) which does not have any electronic modules (V, AW). Advantageously, the method may also provide that: (a) at the end of the sensor (S) which does not have any electronic modules (V, AW), the two tracks (SP
5
, SP
6
) are interconnected by electrical connection elements (VE, LP);(b) the sensor (S) is manufactured in the form of a long band, enabling the user to trim the long band to the required sensor length; and /or (c) the user connects electronic components (V, AW) to the sensor (S) via already existing connection elements (VE, LP).
The present invention further provides an application of the sensor characterized in that the sensor (S) is used for measuring an expansion, and that the longitudinal direction of the tracks (SP
1
, SP
2
, SP
3
, SP
4
, SP
5
, SP
6
) of the sensor (S) are arranged essentially orthogonally to the expansion to be measured.
The present invention also provides an arrangement for compensating for thermal deformations in machine tools using temperature sensors (
7
.
1
,
7
.
2
,
7
.
3
,
7
.
4
) for measuring temperature at at least one machine part (
3
,
4
,
5
), characterized in that at those machine parts (
3
,
4
,
5
), which heat up during operation and which define the distance between the tool and the platen (
1
), temperature sensors (
7
.
1
,
7
.
2
,
7
.
3
,
7
.
4
) are provided, and at those machine parts (
3
,
4
) having a longitudinal extension, elongated temperature sensors (
7
.
1
,
7
.
2
,
7
.
3
) are provided, which are aligned in parallel to the expected deformation direction.
The arrangement advantageously may include that: (a) at least one point-shaped temperature sensor (
7
.
4
) is arranged at one stationary mount (
5
) of a spindle of the C-type machine tool; (b) at a cantilever arm (
4
) of the C-type machine tool, at least one elongated temperature sensor (
7
.
4
) is arranged in parallel to the Y-axis, which covers at least a large portion of the extent of the cantilever arm (
4
) in parallel to the Y-axis; (c) arranged at one frame (
3
) of the C-type machine tool, in parallel to the Z-axis, is it least one elongated temperature sensor (
7
.
1
,
7
.
2
), which covers at least a large portion of the extent of the frame (
3
), in parallel to the Z-axis; (d) the temperature sensors (
7
.
1
,
7
.
2
,
7
.
3
,
7
.
4
) are connected to the machine parts (
3
,
4
,
5
) via a connection featuring good thermal conductivity; (e) the temperature sensors (
7
.
1
,
7
.
2
,
7
.
3
,
7
.
4
) are linked to an evaluation unit; and/or (f) a protective layer is applied to the temperature sensors (
7
.
1
,
7
.
2
,
7
.
3
,
7
.
4
), protecting the temperature sensors (
7
.
1
,
7
.
2
,
7
.
3
,
7
.
4
) from damage and from thermal irradiation.
The present invention provides yet further a method for compensating for thermal deformations on machine tools, in which average temperatures o
Braasch Jan
Günther Torsten
De Jesús Lydia M.
Dr. Johannes Heidenhain GmbH
Gutierrez Diego
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