Hybrid roughness sensor

Abstract

The invention relates to an apparatus comprising a roughness sensor (2) and a skid (10), the roughness sensor having a sensor arm (6) with a stylus tip (8) for measuring roughness, and the skid (10) being mounted on a piezoceramic bending transducer (12).

Description

HYBRID ROUGHNESS TESTER

[0001] The present invention relates to a device comprising a roughness probe with a stylus tip for roughness measurement and a sliding skid associated with the stylus. The invention further relates to a method for roughness measurement.

[0002] In roughness measurement, two basic measurement methods are distinguished - namely skid probing systems and free probing systems.

[0003] Fig. 1 schematically shows a sliding-skid probing system 100. The sliding-skid probing system 100 has a roughness probe 110, which has a stylus arm 112 with a probe tip 114 for measuring the roughness of a measuring object M. The probe tip 114 can also be referred to as a stylus.

[0004] The sliding-skid probing system 100 has a sliding skid 120 which, together with the stylus tip 114, is moved horizontally relative to the object M to scan the surface roughness profile. The measurement profile results from the vertical displacement of the stylus tip 114 relative to the sliding skid 120.

[0005] Sliding skid probing systems are known, for example, from the published patent applications EP 2 199 732 A1 and EP 3 228 974 A1.

[0006] Fig. 2 shows a free-touch probing system 200. The free-touch probing system 200 has a roughness probe 210, which has a probe arm 212 with a probe tip 214 for roughness measurement on a measuring object M. The free-touch probing system 200 can also be referred to as a reference surface probing system.

[0007] In the free-probing system 200, the stylus tip 214 is also moved horizontally across the surface of the object M being measured. The measurement profile results directly and absolutely from the vertical displacement of the stylus tip 114. The reference surface is formed by the plane in which the stylus tip is displaced.

[0008] Slider probing systems have the advantage that, despite their limited measuring range, they are well-suited for curved surfaces and are therefore frequently used to measure the tooth flanks of gears. Furthermore, slider probing systems are insensitive to vibrations and well-suited for very fine surfaces. However, slider probing systems have the disadvantage of not being well-suited for very rough surfaces. This is because the slider, depending on its size and shape, always influences the roughness measurement result, and this influence can significantly alter the results, especially on very rough surfaces.

[0009] Free-touch systems have the advantage of being well-suited for very rough surfaces and allowing the determination of waviness parameters from a filtered waviness profile. However, they have the disadvantage of requiring a highly accurate reference surface, as any form errors that may occur can still influence the roughness measurement profile despite filtering. Furthermore, free-touch systems require a relatively large measuring range for curved surfaces, which places correspondingly high demands on the linearity of the measuring system. Finally, they are sensitive to vibration.

[0010] Against this background, the present invention is based on the technical problem of providing a device and a method for improved roughness measurement and, in particular, combining the advantages of skid probing systems and the advantages of free probing systems.

[0011] The technical problem described above is solved by the features of the independent claims. Further embodiments of the invention are described in the dependent claims and the following description.

[0012] According to one aspect, the invention relates to a device comprising a roughness probe and a sliding skid, wherein the roughness probe has a stylus arm with a stylus tip for roughness measurement. The device is characterized in that the sliding skid is held on a piezoelectric ceramic bending transducer.

[0013] The piezoceramic bending transducer allows the skid to be moved relative to the roughness probe, so that the skid can be moved into an inactive position in which the skid does not make contact with a surface to be scanned during measurement operation.

[0014] The device is specifically designed to be operated as a free-touch system if the skid is held in the inactive position by means of the piezoceramic bending transducer, and to be operated as a skid-touch system if the skid is not held in the inactive position by means of the piezoceramic bending transducer.

[0015] According to one embodiment of the device, the piezoceramic bending transducer can be configured to move the sliding skid into an inactive position.

[0016] Piezoelectric bending transducers are characterized by the fact that their positioning movements can be executed with high repeatability and are reversible.

[0017] It can be provided that the piezoceramic bending transducer has a longitudinal extension that is oriented along a longitudinal extension of the sensing arm of the roughness probe, in particular parallel to the longitudinal extension of the sensing arm of the roughness probe. In this way, the sliding shoe can be aligned relative to the sensing arm or to the roughness probe by means of the piezoceramic bending transducer.

[0018] According to one embodiment of the device, the sliding skid can be arranged on a freely projecting end section of the piezoceramic bending transducer. This allows for optimal utilization of the deformation of the piezoceramic bending transducer under the influence of an electrical voltage, as the resulting displacement of the piezoceramic bending transducer under the influence of an electrical voltage is greatest at the free end of the piezoceramic bending transducer.

[0019] It can be provided that the freely projecting end section of the piezoceramic bending transducer extends over the length of the stylus arm of the roughness probe, with the sliding skid being located further away from a mounting point of the device than the probe tip. According to alternative embodiments, the sliding skid can be positioned closer to a mounting point of the device than the probe tip, or at substantially the same distance. The arrangement can be predetermined by the design. That is, depending on the measurement task, it may be advantageous to design the sliding skid to lead, lag, or be at the same height as the probe tip with respect to the measuring feed.

[0020] According to one embodiment of the device, the piezoceramic bending transducer can be a plate-shaped component, in particular, the piezoceramic bending transducer has a length that is at least ten times its thickness and at least five times its width.

[0021] It may be provided that the length of the piezoceramic bending transducer is less than or equal to 10 cm, in particular less than or equal to 5 cm, and / or the width of the piezoceramic bending transducer is less than or equal to 2 cm, in particular less than or equal to 1 cm, and / or the thickness of the piezoceramic bending transducer is less than or equal to 2 mm, in particular less than or equal to 1 mm.

[0022] It can be provided that the deflection of the sliding shoe by means of the piezoceramic bending transducer is less than or equal to 3 mm, in particular less than or equal to 2 mm. In other words, the piezoceramic bending transducer can be configured to achieve a deflection of the sliding shoe of less than or equal to 3 mm, in particular less than or equal to 2 mm. to cause bending of less than or equal to 2 mm, and of more than 0 mm, in particular by applying an operating voltage to the piezoceramic bending transducer.

[0023] Piezoceramic bending transducers are well-known and represent the state of the art. In particular, four different types of piezoceramic bending transducers are known, each comprising one or more piezoceramics and, optionally, a passive layer. These types can be described as "monomorph," "bimorph," "trimorph," or "multimorph." Specifically, the piezoceramic bending transducer used here is a piezoceramic bending transducer with a unidirectional polarization or bending direction.

[0024] For example, depending on the design, an operating voltage of 300 V, 230 V or 130 V, in particular 100 V or more and 300 V or less, can be applied to the piezoceramic bending transducer to effect the deformation or positioning movement.

[0025] According to one embodiment of the device, the piezoceramic bending transducer, viewed in cross-section, can be arranged on a side of the stylus arm of the roughness probe facing away from the stylus tip.

[0026] It can be provided that the piezoceramic bending transducer is attached to a housing, wherein the sensing arm of the roughness probe penetrates an opening in the housing and is arranged to be freely movable within the opening relative to the housing.

[0027] The invention further relates to a method for roughness measurement, wherein a device according to the invention is used, comprising the method step: measuring the roughness of a surface to be measured using the roughness probe, wherein the sliding skid rests against the surface to be measured during the measurement or wherein the sliding skid is arranged to be held in an inactive position during the measurement using the piezoceramic bending transducer and does not rest against the surface to be measured.

[0028] The roughness of the surface to be measured can be measured by operating the device as a free-probing system, in which the sliding skid is moved by means of the The piezoelectric bending transducer is held in the inactive position. This means that the piezoelectric bending transducer is deformed by applying a voltage to move the sliding skid into the active position and hold it there.

[0029] The roughness of the surface to be measured can be measured by operating the device as a sliding-skid probe system, in which the sliding skid is not held in an inactive position by means of the piezoceramic bending transducer – but in other words, in an active position, in contact with the surface to be measured. This means that the piezoceramic bending transducer is not deformed by applying a voltage.

[0030] The invention is explained in more detail below with reference to an exemplary embodiment shown in a drawing. The drawing schematically depicts: Fig. 1 shows a skid-type probing system according to the prior art; Fig. 2 shows a free touch system according to the prior art; Fig. 3 shows a device according to the invention in a cross-section in a first operating state as a skid probe system; Fig. 4 shows the device according to the invention from Fig. 3 in a second operating state as a free touch system; Fig. 5 shows a process step of the process according to the invention; Fig. 6 Types of piezoceramic bending transducers according to the state of the art; Fig. 7 shows the device according to the invention from Fig. 3 in the first operating state as a skid sensing system; Fig. 8 shows the device according to the invention from Fig. 3 in the second operating state as a free touch system.

[0031] Fig. 3 shows a device 2. The device 2 has a roughness probe 4. The roughness probe 4 has a probe arm 6 with a probe tip 8 for roughness measurement.

[0032] The device 2 has a sliding skid 10.

[0033] The sliding skid 10 is held on a piezoceramic bending transducer 12. The piezoceramic bending transducer 12 can be deflected by applying an operating voltage U, as shown in Fig. 4. The deflection is completely reversible.

[0034] The device 2 can therefore be operated as a skid probing system, as shown in Fig. 3, or can be operated as a free probing system, as shown in Fig. 4.

[0035] The piezoceramic bending transducer 12 has a longitudinal extent L1 that is oriented along a longitudinal extent L2 of the sensing arm 6 of the roughness probe 4, or is oriented essentially parallel to the longitudinal extent L2 of the sensing arm 6 of the roughness probe 4. The term "essentially parallel" is used here because the roughness probe 4 is mounted to be movable relative to the piezoceramic bending transducer 12 in order to enable roughness measurement in a known manner.

[0036] The deflection A in Fig. 4 is greatly exaggerated for illustrative purposes. In practice, the deflection A is in the low single-digit millimeter range, or even less than three millimeters (mm) or less than 2 mm.

[0037] The sliding skid 10 is arranged on a freely projecting end section 14 of the piezoceramic bending transducer 12.

[0038] The freely projecting end section 14 of the piezoceramic bending transducer 12 extends over a length L2 of the stylus arm 6 of the roughness probe 4, with the sliding skid 10 having a greater distance to a suspension 20 of the device 2 than the probe tip 8. According to alternative embodiments, the sliding skid can be arranged next to or at the level of the probe tip instead of the lagging arrangement shown here, or it can be arranged leading the probe tip.

[0039] The piezoceramic bending transducer 12 is a plate-shaped component.

[0040] The piezoceramic bending transducer has a length L1 that is at least ten times its thickness D1 and at least five times its width B1 measured perpendicular to the plane of the drawing.

[0041] The length L1 of the piezoceramic bending transducer 12 is less than 10 cm.

[0042] The width B1 of the piezoceramic bending transducer 12 is less than 2 cm. To illustrate the width B1, a single, interrupted view of the bending transducer 12 in a top view is shown in the lower part of Fig. 3.

[0043] The thickness D1 of the piezoceramic bending transducer is less than 2 mm.

[0044] The piezoceramic bending transducer 12 is arranged in the cross-section shown on one side of the stylus arm 6 of the roughness probe 4 facing away from the stylus tip 8.

[0045] The piezoceramic bending transducer 12 is attached to a housing 16 of the device 2.

[0046] The probe arm 6 of the roughness probe 4 penetrates an opening 18 of the housing 16 and is arranged to be freely movable within the opening 18 relative to the housing 16.

[0047] The piezoceramic bending transducer 12 is thus configured to move the sliding skid 10 into an inactive position (Fig. 4) to enable the operation of the device as a free-touch system, and to reversibly return the sliding skid 10 from the inactive position to the active position (Fig. 3) to enable the operation of the device 2 as a sliding skid touch system.

[0048] A method for roughness measurement is described, using the device 2, comprising the method step: (A) measuring the roughness of a surface O to be measured using the roughness probe 4, wherein the sliding skid 10 rests against the surface O to be measured during the measurement (Fig. 3; Fig. 7) or wherein the sliding skid 10 is in the inactive position during the measurement using the piezoceramic bending transducer 12 Position is held and is not in contact with the surface to be measured (Fig. 4; Fig. 8).

[0049] Piezoelectric ceramic bending transducers are well-known and represent the state of the art. Figure 6 shows four different types of piezoceramic bending transducers 12 as examples and schematically, each comprising one or more piezoceramics 22 and optionally a passive layer 24. The types can be described as (I) monomorphic, (II) bimorphic, (III) trimorphic, or (IV) multimorphic.

[0050] Fig. 7 shows the device 2 according to the invention from Fig. 3 in the first operating state as a skid probing system, wherein a surface O of a curved measuring object R to be measured is scanned.

[0051] Fig. 8 shows the device 2 according to the invention from Fig. 3 in the second operating state as a free-probing system, wherein the surface O of the curved object R to be measured is scanned. The movement of the roughness probe 4 should be tangential to the curved surface of the object R to be scanned. REFERENCE MARK 2 Device 4 roughness probes 6 Touch arm 8 probe tip 10 skid 12 piezoceramic bending transducers 14 Final Section 16 cases 18 Opening 20 Suspension 22 Piezoceramics 24 passive position 100 sliding skid sensing system 110 roughness probes 112 Test arm 114 Probe tip 120 skid 200 Free touch system 210 roughness probes 212 Test arm 214 Probe tip A deflection B1 width D1 thickness L1 Longitudinal extent L2 Longitudinal extension M measurement object 0 surface area to be measured R Measuring object Operating voltage

Claims

PATENT CLAIMS:

1. Device comprising a roughness probe (4) and a sliding skid (10), wherein the roughness probe (4) has a stylus arm (6) with a stylus tip (8) for roughness measurement, characterized in that the sliding skid (10) is held on a piezoceramic bending transducer (12).

2. Device according to claim 1 , characterized in that the piezoceramic bending transducer (12) has a longitudinal extent (L1 ) which is oriented along a longitudinal extent (L2) of the sensing arm (6) of the roughness probe (4).

3. Device according to one of the preceding claims, characterized in that the sliding skid (10) is arranged on a freely projecting end section (14) of the piezoceramic bending transducer (12).

4. Device according to claim 2 and claim 3, characterized in that the freely projecting end section (14) of the piezoceramic bending transducer (12) extends projecting over a length (L2) of the stylus arm (6) of the roughness probe (4), wherein the sliding skid (10) has a greater distance to a suspension (20) of the device (2) than the probe tip (8).

5. Device according to one of the preceding claims, characterized in that the piezoceramic bending transducer (12) is a plate-shaped component, in particular that the piezoceramic bending transducer (12) has a length (L1 ) that corresponds to at least ten times its thickness (D1 ) and to at least five times its width (B2).

6. Device according to one of the preceding claims, characterized in that the length (L1 ) of the piezoceramic bending transducer (12) is less than or equal to 10 cm, in particular less than or equal to 5 cm, and / or the width (B1 ) of the piezoceramic bending transducer (12) is less than or equal to 2 cm, in particular less than or equal to 1 cm, and / or the thickness (D1 ) of the piezoceramic bending transducer (12) is less than or equal to 2 mm, in particular less than or equal to 1 mm.

7. Device according to one of the preceding claims, characterized in that the piezoceramic bending transducer (12) is arranged in cross-section on a side of the stylus arm (6) of the roughness probe (4) facing away from the stylus tip (8).

8. Device according to one of the preceding claims, characterized in that the piezoceramic bending transducer (12) is attached to a housing (16), wherein the sensing arm (6) of the roughness probe (4) penetrates an opening (18) of the housing (16) and is arranged to be freely movable within the opening (18) relative to the housing (16).

9. Device according to one of the preceding claims, characterized in that the piezoceramic bending transducer (12) is configured to move the sliding skid (10) into an inactive position.

10. Method for roughness measurement, wherein a device according to one of the preceding claims is used, comprising the method step: Measuring the roughness of a surface to be measured using the roughness probe (4), wherein the sliding skid (10) rests against the surface to be measured during the measurement, or wherein the sliding skid is held against the surface to be measured during the measurement using the The piezoceramic bending transducer (12) is held in the inactive position and is not in contact with the surface to be measured.

Images