LINEAR GUIDING DEVICE FOR A FEED AXIS OF A MACHINE TOOL

Abstract

The invention relates to a linear guiding device (1) for a feed axis (2), preferably a machine tool (3), comprising at least the following components: At least one sensor surface (4) of the linear guiding device (1) for linearly guiding a carriage (5) or a spindle nut (6); at least one microsensor (7), preferably at least one strain gage (8, 9, 10, 11, 12) and/or at least one resistance temperature sensor (13, 14), for detecting an expansion and/or compression and/or temperature of at least one sensor surface (4), wherein at least one microsensor (7) is permanently connected to at least one sensor surface (4).

With the present invention, a load on a linear guiding device can be directly measured during the machine's operation.

Claims

1. A linear guiding device (1) for a feed axis (2), preferably for a machine tool (3), comprising at least the following components: At least one sensor surface (4) of the linear guiding device (1), the linear guiding device (1) being designed for the linear guidance of a carriage (5) or a spindle nut (6); at least one microsensor (7), preferably at least one strain gage (8, 9, 10, 11, 12) and/or at least one resistance temperature sensor (13, 14), for detecting an expansion and/or compression and/or temperature of at least one sensor surface (4); characterized in that at least one microsensor (7) is permanently connected to at least one sensor surface (4).

2. The linear guiding device (1) according to claim 1, wherein at least one microsensor (7) has at least one strain gage (8,9,10,11,12) with a single measuring orientation (15) in at least one of the following arrangements: Transversely on a central line (16) between two bearing sides (17, 18); at least two strain gages (8, 9, 10, 11, 12) are respectively transverse to the measuring direction (15) and equidistant to a central line (16) between two bearing sides (17, 18); with the measuring orientation (15) along a central line (16) between two bearing sides (17, 18).

3. The linear guiding device (1) according to claim 1, wherein at least one microsensor (7) is secured by means of at least one of the following manufacturing processes: (7) is closed by means of the embedded microsensor (7), preferably by means of partial embedding and/or by means of soldering. (DE). WIPO Home services World Intellectual Property Organization, wherein at least one microsensor (7) is preferably a film sensor and is introduced into the recess (19, 20) in a rolled manner; embedding at least one microsensor (7) during the casting, preferably continuous casting, of the linear guiding device (1); extensive gluing of at least one microsensor (7) to at least one sensor surface (4); and extensive thin-film application of the microsensor (7) on at least one sensor surface (4).

4. The linear guiding device (1) according to claim 1, wherein a number of microsensors (7) are arranged over a length (21) of at least one sensor surface (4), where the density of the microsensors (7), preferably from a machine tool (3), is higher than in a pure transport section (23), preferably from a machine tool (3).

5. A method for the thin-film application of a microsensor (7) on a linear guiding device (1), comprising the following steps: a. applying an electrically insulating first layer (24) to a sensor surface (4) of a linear guiding device (1) to be detected; b. applying an electrically conductive second layer (25) to the first layer (24); c. patterning the second layer (25); d. applying an electrically insulating and mechanically robust third layer (26) by means of which the second layer (25) is electrically insulated and mechanically protected from the outside, the third layer (26) preferably being formed from aluminum oxide; and e. before, during or after step b. Application of line connections (27, 28) for connecting the second layer (25) to a measuring device (29).

6. The method for thin-film application of a microsensor (7) according to claim 5, wherein before step a. In a step a1. A recess (19, 20) of at least the depth (30) and at least the surface (31) of the microsensor (7) is introduced into the sensor surface (4).

7. A method for introducing a microsensor (7) into a linear guiding device (1), wherein the microsensor (7) is preferably a film sensor, having at least the following steps: i. Arranging the microsensor (7) to a predetermined position; ii. Casting and/or soldering at least a part of the linear guiding device (1) to the positioned microsensor (7); iii. Before, during or after step i. Positioning the line connections (27, 28) on the microsensor (7) for a measuring device (29).

8. The method for introducing a microsensor (7) according to claim 7, wherein the linear guiding device (1), has been completed, preferably completely, before step i (7) and wherein the microsensor (7), in step i), is provided with at least one depression (19, 20) for at least one microsensor (7) by means of the depression (19, 20), and wherein in step ii. the depression (19, 20) is closed by partial casting and/or soldering and the microsensor (7) is fixed.

9. The method of introducing a microsensor (7) according to claim 7, wherein the linear guiding device (1) at least one of the following treatment steps after step ii is supplied, preferably after step iii: Surface hardening of the linear guiding device (1); and starting the linear guiding device (1)

10. A computer-executable method for detecting loads in a linear guiding device (1) with at least one microsensor (7) according to claim 1, characterized in that a plurality of strain gages (8, 9, 10, 11, 12) (8, 9, 10, 11, 12), wherein the shape and modulus of elasticity of the linear guiding device (1) determine the orientation and position of the strain gages (4) in the measuring direction (15) 8,9,10,11,12), and wherein, on the basis of the respective resistance changes of the strain gages (8, 9, 10, 11, 12) together with the stored values of the form, E-module and position the applied linear force 33,34, 35) and/or the adjoining torque (36, 37, 38) is calculated, preferably the duration of the service life being extrapolated therefrom and/or measures for increasing the service life.

Description

BRIEF DESCRIPTION

[0121] The above-described invention is explained in detail below in the technical background, with reference to the accompanying drawings showing preferred embodiments. The invention is in no way limited by the purely schematic drawings, where it is to be noted that the drawings are not dimensionally accurate and are not suitable for defining size ratios. It is shown in

[0122] FIG. 1: a linear guiding device with different measuring arrangements;

[0123] FIG. 2: a guide rail in cross-section;

[0124] FIG. 3: a spindle drive with spindle nut;

[0125] FIG. 4: a machine tool; and

[0126] FIG. 5: a microsensor on a sensor surface in the section.

[0127] In FIG. 1 shows a linear guiding device 1, here a profile rail for a ball bearing carriage (not shown). On one of the possible sensor surfaces 4, in this case the top side of the profile rail, between the (directly loadable) first bearing side 17 and the second bearing side 18, various configurations of microsensors 7 (7a, 7b, 7c) are presented with in part a number of expansion strips, which are arranged with partly different measuring alignments 15 (double arrow). In this case, the linear guiding device 1 can be screwed several times from the top along the center line 16. The center line 16 defines the x-axis 43, to which the z-axis 45 is defined in a conventional manner in the installation upwards, as shown in the figure. The alignment of the y-axis 44 results from the usual standard as shown. In addition to the linear guiding device 1, an x-force 33 (which will have no influence because it is the only free direction) and an x-torque 36 with a common double arrow are shown because of the better displayability. Similarly, a y-force 34 and a y-torque 37, as well as a z-force 35 and a z-torque 38 are shown.

[0128] In the case of the first microsensor 7a, two strain gages 9 and 10 are arranged on the right and left of the central line 16 with their measuring direction 15 transversely with respect to the center line 16. In the case of tensile loading (z-force 35 in the direction of the arrow), both strain gages 9 and 10 are compressed, (force 35 opposite the direction of the arrow), both strain gages 9 and 10 are stretched. In the case of a force introduction from the side (y-force 34), a strain gage is compressed (at y-force 34 in the direction of the arrow strain gage 9), the other stretched (then strain gage 10). The same measurement arises at a z-torque 38 and an x-torque 36. With this arrangement, in addition to the absolute height, the direction of the force introduction can also be determined.

[0129] In the case of the second microsensor 7b, only a strain gage 8 which is aligned with its measuring direction 15 transversely with respect to the center line is used. This can only distinguish between tensile load and compressive load (compression or expansion), but can only detect conditionally lateral forces and moments. However, this variant represents a cost-effective alternative.

[0130] In the case of the third microsensor 7c, the two measuring strain gages 9 and 10, unlike the first microsensor 7a, do not lie in a line, but are offset with respect to one another along the center line 16. In the case of the third microsensor 7c, all measured values can nevertheless be recorded as in the case of the first microsensor 7a. In addition, the speed and the direction of movement of the guide carriage can be additionally detected in dynamic use, that is to say, as the guide carriage moves. Furthermore, two further strain gages 11 and 12 are shown in the third microsensor 7c, the measuring orientation 15 of which is rotated by 90 relative to the measurement direction 15 of the strain gages 9 and 10. Thus, although these strain gages 11 and 12 do not measure the deformation of the linear guiding device 1, the linear guiding device 1 is very rigid in this direction. However, temperature compensation is possible because they are subjected to the same thermal influences as the strain gages 9 and 10 and serve as resistance temperature sensors 13 and 14.

[0131] The microsensors 7 can be read out by corresponding electronics. Expediently, they are interconnected in a Wheatstone measuring bridge. The measurement can be carried out via a two-wire measurement, three-wire measurement, four-wire measurement or six-wire measurement.

[0132] The microsensors 7 can be read out either individually, with or without temperature compensation, or in the case of two strain gages (microsensors 7a and 7c) arranged in a crossed half bridge, also with or without temperature compensation. In the case of the crossed half bridge, however, the information about laterally acting forces and torques about the longitudinal axis of the guide rail is lost. However, the interconnection is twice as sensitive as the second microsensor 7b.

[0133] In FIG. 2 shows a linear guiding device 1, in this case a profile rail with a basic construction as in FIG. 1, shown in cross-section. In this case, the ball bearing surfaces 39, 40, 41 and 42 on the two bearing sides 17 and 18 are clearly visible. Here, three possible sensor surfaces 4 are designated, wherein also the two bearing sides 17 and 18 represent suitable surfaces. In this example, the microsensors 7 are not arranged on the surface. Rather, the strain gages 9 and 10 are in each case arranged in depression 19 or 20, which are here, for example, first drilled and then filled by partial casting after the positioning of the strain gages 9 and 10. Therefore, the microsensors 7 are embedded in the linear guiding device 1. The determined measurements thereby refer approximately to the lateral sensor surfaces 4 on the bearing side 17 or 18. The measuring direction 15 is in this case configured in particular for the z-force 35 along the z-axis 45 (equal tensile load or pressure load on both strain gages 9 and 10) and for an x-torque 36 about the x-axis 43 (in each case opposite tensile load and pressure load on the strain gages 9 and 10), as well as for a transverse force (y-force 34) along the y-axis 44 (in each case opposite tensile load and compressive load on the y-axis strain gages 9 and 10). The measuring signals, shown here purely schematically, are forwarded by means of the first and second line connections 27 and 28 to measuring device 29, where they are connected to a measured value, for example, by means of a Wheatstone bridge.

[0134] In FIG. 3, a linear guiding device 1 is shown as a ball screw drive 51, on which an axially movable spindle nut 6 is arranged. The spindle nut 6 is displaceable in the region of the threaded portion 46. For this purpose, the ball screw drive 51 is rotatable by means of drive 48. The ball screw drive 51 also has a shaft section 47 on which no thread is arranged. A microsensor 7 is arranged in shaft section 47, which is preferably designed as shown here with two measuring directions 15 which are arranged orthogonally to one another and are inclined by 45 to a vertical cross-sectional plane. This allows torque loads occurring in the ball screw drive 51 to be detected.

[0135] In FIG. 4, a simplified machine tool 3 is shown which has a first feed axis 2 for a workpiece 58 and a second feed axis 53 for a tool 57. By means of a first ball screw drive 51, a first carriage 5 can be moved along the first feed axis 2 on a first (paired) profile rail 49. For this purpose, the first spindle nut 6 is firmly attached to the guided first carriage 5. By means of the first drive 48, the first ball screw drive 51 is rotated in a controlled manner. Similarly, the second feed axis 53 is equipped with a second drive 56, a second ball screw drive 52 and a second spindle nut 55, and the second carriage 54 is guided via a second (paired) profile rail 50. It is suggested here to arrange microsensors (not shown here) depending on the loads on the length 21 of the first profile rails 49. Two pure transport sections 23 are formed in which no processing can take place and a machining section 22 arranged in between, in which tool 57 initiates forces on workpiece 58 and therefore onto the first profile rail 49. A transport section 23 is, for example, provided for the better removability or tensionability of workpiece 58.

[0136] In FIG. 5 a section of a linear guiding device 1 as a profile rail 49 is shown in the section. In this case, a microsensor 7 is arranged in a sensor surface 4, here the bearing side 18. In this case, the depth 30 and the (total) surface 31 are adapted to the (desired) size of the microsensor 7. Furthermore, negative structure 59 is introduced into sensor surface 4 during the shaping of the blank of the linear guiding device 1 or subsequently. The first layer 24 is then applied so that the entire structure is superimposed, but the negative structure 59 is retained at the same time. Subsequently, the second layer 25 is applied so that the negative structure 59 is, as a rule, completely filled. Regions of the first layer 24 and the regions of the second layer 25 which are not associated with the conductor track 32 extend beyond the plane of the sensor surface 4. Subsequently, for example in a grinding process, the excess parts of the first layer 24 and of the second layer 25 are also removed so that the conductor track 32, for example meandering, is produced. Thus, the patterning is carried out simultaneously with a processing step of the linear guiding device 1. Finally, the third layer 26 is applied and the line connection 27, preferably by means of soldering or wire bonding, is connected to the second layer 25, preferably by means of etching, ultrasonic machining or chip-piercing penetration of the third layer 26. Microsensor 7 is therefore well protected from mechanical influences. The first layer 24 is arranged as an electrical insulator and the third layer 26 is designed as a mechanical protection and as an electrical insulator. The second layer 25 is electrically conductive and has the desired sensor properties. This is connected to a line connection 27, which supplies the measurement signal to a measuring device 29 (not shown) (compare FIG. 2).

[0137] With the present invention, a load on a linear guiding device can be directly measured during the machine's operation.

LIST OF REFERENCE NUMBERS

[0138] 1 Linear guiding device [0139] 2 First feed axis [0140] 3 Machine tool [0141] 4 Sensor surface [0142] 5 First carriage [0143] 6 First spindle nut [0144] 7 Microsensor [0145] 8 First strain gage [0146] 9 Second strain gage [0147] 10 Third strain gage [0148] 11 Fourth strain gage [0149] 12 Fifth strain gage [0150] 13 First resistance temperature sensor [0151] 14 Second resistance temperature sensor [0152] 15 Measuring alignment [0153] 16 Center line [0154] 17 First bearing side [0155] 18 Second bearing side [0156] 19 First deepening [0157] 20 Second depression [0158] 21 Length [0159] 22 Machining section [0160] 23 Transport section [0161] 24 First layer [0162] 25 Second layer [0163] 26 Third layer [0164] 27 First line connection [0165] 28 Second line connection [0166] 29 Measuring device [0167] 30 Depth [0168] 31 Area [0169] 32 Conductor path [0170] 33 x-force [0171] 34 y-force [0172] 35 z-force [0173] 36 x-torque [0174] 37 y-torque [0175] 38 z-torque [0176] 39 First ball bearing surface [0177] 40 Second ball bearing surface [0178] 41 Third ball bearing surface [0179] 42 Fourth ball bearing surface [0180] 43 x-axis [0181] 44 y-axis [0182] 45 z-axis [0183] 46 Threaded portion [0184] 47 Shaft section [0185] 48 First drive [0186] 49 First profile rail [0187] 50 Second profile rail [0188] 51 First ball screw drive [0189] 52 Second ball screw drive [0190] 53 Second feed axis [0191] 54 Second carriage [0192] 55 Second spindle nut [0193] 56 Second drive [0194] 57 Tool [0195] 58 Workpiece [0196] 59 Negative structure