Sample holder device for a grinding device and method for producing a microscopically flat surface on a sample

Abstract

Sample holder device (1) for a grinding device, comprising a base body (10) aligned with respect to a central axis (M), which includes a recess (15) open towards a top surface (12) with a sample receiving chamber (16), and a clamping device (30) for clamping a sample (50) in the sample receiving chamber (16), wherein at least one mounting element (20) for mounting on a grinding wheel during the grinding process is detachably arranged on the top surface (12) of the base body (10), characterized by that in the sample receiving chamber (16) an axially adjustable depth stop device (40) with at least one depth stop surface (41) for axial positioning of the sample (50) is provided, that the clamping device (30) has clamping means (31) and a planar clamping element (32) which are arranged such that a clamping force can be applied to the specimen (50) orthogonally to a flat side wall (151') of the recess (15), that the at least one mounting element (20) is designed to be large-area, wherein an upwardly directed grinding surface (21) of the mounting element (20), facing away from the top surface (12), is larger than 200% of a grinding surface of the sample (50), that in the plane of the top surface (12) of the base body (10) the ratio of a top surface (121) of the base body (10) to the size of the opening of the recess (15) is at least 2 : 1 and that, when assembled, the mounting element (20) covers at least 70% or at least 90% of the top surface (121).

Description

[0001] The invention relates to a sample holder device for a grinding machine, comprising a base body aligned with respect to a central axis, which includes a recess open towards a top surface and containing a sample receiving chamber, and a clamping device for clamping a sample in the sample receiving chamber, wherein at least one mounting element for placing onto a grinding wheel during the grinding process is detachably arranged on the top surface of the base body. The invention further relates to a method for producing a microscopically flat surface on a sample.

[0002] For materials research purposes, it is common practice to prepare material samples with a microsection to allow microscopic examination of their structure or microstructure. A common procedure involves embedding these microsections in a plastic substrate made of embedding resin. Alternatively, the samples can be glued to a support. The samples are then ground, possibly in several steps, to prepare the surface for viewing under a light or electron microscope. If space is limited for microscopy, such as when investigating microstructure evolution as a function of temperature using a heating chamber, mechanically or temperature-stable samples can be removed from the plastic substrate or the support by breaking or heating the embedding resin.

[0003] Disadvantages arise with samples that are sensitive (especially mechanically and / or temperature-sensitive), such as carbon fiber reinforced plastics (CFRP) or porous materials like carbon fiber reinforced carbon (C / C). These cannot be removed from the substrate without damage. When such a sample is bonded, the adhesive can penetrate the sample material and alter its microstructure.

[0004] Therefore, there is a need for a sample holder that allows samples to be held without embedding and ground and / or polished using a grinding device or polishing machine. Such a sample holder, which is also the basis of the present invention, is known, for example, from DE 10 2012 017 662 A1. However, it has been found that this known sample holder is not suitable for grinding (mechanically or temperature-sensitive) and / or small-volume samples, since there is a high risk of sample damage, particularly when clamping the sample and / or during the grinding process, and / or the sample cannot be clamped securely.

[0005] Another sample holder for holding a sample without embedding for an older type of grinding device is known from DE 695 28 630 T2. With this known sample holder, precise machining can be difficult, partly because it lacks a mounting element. This results in high axial pressure on the sample due to the grinding pressure, which increases with the size of the sample surface to be ground. The high grinding pressure leads to high material removal rates and poor surface finishes, e.g., due to material breakouts within the sample surfaces, especially with porous samples. Furthermore, there is a risk of damaging the sample due to the high contact pressure.

[0006] DE 90 10 700 U1 discloses a holding device for the production of polished specimens, wherein a block has means for locking and / or position adjustment, specifically screws. The screws are arranged on the bottom side of a recess in the block.

[0007] DE 90 15 096 U1 discloses a saw for cutting material samples, in which several sample holders are disclosed, but no sample holder device for a grinding device.

[0008] German patent DE 11 2019 004 919 T5 describes a sacrificial clamp for preparing a thin sample for infrared microscopy. This document does not show a sample holder for a grinding device.

[0009] The present invention is based on the objective of providing a sample holder device and a method for producing a microscopically flat surface on a sample, by means of which even sensitive samples, e.g. consisting of CFRP materials and / or small volume samples, can be ground precisely and with as little effort as possible.

[0010] The problem is solved for the sample holder device with the features of claim 1 and for the method with the features of claim 9. With regard to the sample holder device, it is provided that an axially adjustable depth stop device with at least one depth stop surface for axial positioning of the sample is provided in the sample receiving chamber.

[0011] The depth stop device can comprise a depth stop element, particularly an elongated one, to which the depth stop surface can be assigned. The axially adjustable depth stop device allows the sample holding space to be used for samples of different sizes, including small ones (e.g., all dimensions less than or equal to 10 mm), while enabling relatively precise axial pre-positioning of one side of the sample to be ground. The depth stop device can advantageously compensate, at least partially or predominantly, for the contact force of the grinding device, which presses the sample holder device axially onto a grinding wheel during grinding. This compensation is achieved in an axially parallel and opposite direction. In this way, the force acting on the sample to compensate for the contact force can be advantageously kept lower than if a compensating force were applied solely in another way or from a different direction, e.g.,...by frictional locking through clamping of the sample perpendicular to the axial contact force.

[0012] In a design that is easy to assemble and saves material, the depth stop surface can be formed by the end face of a screw, with the depth stop element itself being formed by a screw. Alternatively, the depth stop surface can be a separate surface element, e.g., arranged on the depth stop element or the screw, allowing for a customized shape during manufacturing, e.g., adapted to the sample holding area. Preferably, the depth stop element can be designed as a setscrew. This allows the contact pressure to be applied unimpeded to the underside of the base body during the grinding process using a pressure device of the grinding unit.

[0013] According to the invention, the at least one mounting element is designed with a large surface area, wherein an upwardly directed grinding surface of the mounting element, i.e., facing away from the top surface, is larger than 200% of a grinding surface of the sample. In the case of multiple mounting elements, the size specification refers to the sum of the grinding surfaces. Such a large surface area advantageously results in a large total surface area, thereby reducing the contact pressure, i.e., the force applied by the grinding device per unit area. Furthermore, the contact pressure can be kept largely constant regardless of the size of the grinding surface of the sample. Thus, the pressure on the sample can be kept comparatively low, preventing sample damage. This makes the sample holder device advantageously suitable even for delicate samples.Furthermore, tilting of the sample holder during grinding, and thus an angled grinding of the sample, can be prevented.

[0014] Advantageously, at least two, and preferably a maximum of two, mounting elements are provided, arranged in such a way that they create a recess for the opening of the recess. This recess allows for easy insertion of the sample, particularly if the recess also has open sides (for example, sides adjacent to a circumferential surface). Having a maximum of two mounting elements simplifies the process, as only two mounting elements need to be positioned and secured.

[0015] Easy handling of the sample holder, such as attaching and / or removing the mounting element, possibly using a gripping device like tweezers or pliers, is achieved by making the mounting element(s) from a material softer than the sample, particularly a plastic. Furthermore, this results in cost and manufacturing advantages, allowing for the use of injection molding or 3D printing processes, for example.

[0016] In a preferred embodiment, the mounting element(s) has a thickness of 0.5 mm to 5 mm, preferably 1 mm to 4 mm, e.g., between 1 mm and 2 mm, before the first grinding operation. The minimum thickness is such that sufficient wear material is present so that the mounting element(s) is / are not completely worn away during at least one grinding operation. In particular, unevenness in the clamping of the specimen can be compensated for by a "grinding" process, and a uniform grinding surface can be created initially. The maximum thickness depends on the type, especially the dimensions and the stability or properties, of the specimen: The maximum thickness should be such that secure clamping of the specimen is ensured, with the specimen protruding, for example, at least 3 mm into the recess. In extreme cases, the mounting elements could be omitted for very small specimens.Furthermore, the maximum thickness should be such that the maximum possible, material-dependent protrusion of the sample above the top of the base body is not exceeded, in order to guarantee a non-destructive grinding process. Considering these criteria, comparatively thick mounting elements, e.g., up to 5 mm, offer corresponding economic advantages with a comparatively low replacement requirement.

[0017] Advantageous assembly options arise when the mounting element(s) is / are detachably attached to the base body by means of an interference fit or a positive-locking connection, e.g., a click connection (with elastically deformable, spring-loaded engagement elements as connection structures). For this purpose, the corresponding connection structures are present on the mounting element(s) and the base body. For example, one or more engagement elements are formed as outer circumferential contours on the mounting element, and corresponding complementary counter-elements with complementary inner circumferential contours are formed on the base body, or vice versa, which interlock. This enables a simple type of fastening, e.g., in the case of an interference fit, similar to the principle of a modular system. If necessary, especially after grinding, the connection can be easily released again, e.g., using a gripping tool such as pliers or tweezers.For ease of handling, it can be advantageous if the mounting element is made of plastic.

[0018] In the embodiment according to the invention, the clamping device comprises clamping means and a planar clamping element arranged such that a planar clamping force can be applied to the specimen orthogonally to a planar side wall of the specimen holding chamber, in particular one perpendicular to the surface of the cross-section. Specifically, the planar side of the clamping element contacts the planar side of the specimen. The planar clamping element is, in particular, designed in the form of a clamping jaw and can be present either loosely or pre-assembled on the base body (e.g., on the clamping means) before clamping the specimen. By means of the clamping element, the specimen can be clamped by applying a clamping force via the clamping means, e.g., against one of the side walls as a counter surface, whereby the specimen holding chamber—whose width can be varied as a result—is formed between the clamping element and the corresponding side wall.The clamping element is designed to be at least planar enough to distribute the clamping force evenly across the sample, thereby reducing the applied pressure and preventing sample damage, particularly crushing. Furthermore, the clamping element is preferably made of a material hard enough, such as steel, to transmit the clamping force across the entire surface of the sample. This allows the clamping force to be applied perpendicular to the contact pressure of the grinding device. Such a clamping design permits the use of the sample holder with small and / or delicate samples (dimensions of all three dimensions < 10 mm, for example, 7 mm x 5 mm x 3 mm).

[0019] If the flat clamping element has a recess on the side facing the depth stop surface, into which the depth stop surface can be axially adjusted parallel to the central axis, it is advantageous to prevent the width of the sample holding space from being limited by the flat clamping element striking the depth stop surface or the depth stop element itself. In this way, the limitation of the sample holder's use with regard to the width or thickness of a sample can be reduced or eliminated.

[0020] Easy insertion of the sample into the sample holding chamber can be achieved by designing the recess to be elongated and open at least on one side towards the circumferential surface of the base body. The recess can, for example, be elongated, forming a groove, and open on both sides facing the circumferential surfaces or adjacent to the circumferential surface of the base body. For a uniform grinding result, the recess can, for example, be symmetrically shaped in the base body.

[0021] According to the invention, an advantageous force distribution with a comparatively low force acting on the specimen during the grinding process is achieved by ensuring that, in the plane of the top surface of the base body, the ratio of the top surface of the base body to the size of the opening of the recess is at least 2:1, e.g., 2.9:1, and that, in the mounted state, the mounting element covers at least 70% or at least 90% of the top surface. For example, the ratio of the grinding surface of the mounting element to the size of the opening of the recess can be 2.9:1. A lower coverage ratio is possible with a hard material than with a soft material of the mounting element(s).

[0022] The process can advantageously include a first grinding step involving a coarse grinding operation. Using a coarser grinding wheel (i.e., with a coarser grit than in subsequent grinding steps), a macroscopically flat grinding surface is produced. In this process, the grinding surface of the mounting element and the side of the specimen to be ground are ground in such a way that they lie in a common, macroscopically flat grinding plane, upon which the contact pressure is distributed essentially uniformly. Any inaccuracies in the insertion of the specimen, such as slight tilting, are compensated for by this step. Thus, the coarse grit creates the conditions for a uniform grinding result with low pressure on the specimen in a relatively short time. A relatively soft, e.g.,Using a plastic attachment element can accelerate this process step and minimize wear on the grinding wheel. The grinding result can be optimized by selecting an attachment element material adapted to the sample hardness or grinding resistance, e.g., plastic, metal, and / or ceramic.

[0023] The invention further relates to a mounting element and a base body, each designed to be used in the sample holder device, in particular each according to the design variant(s) as specified in connection with the sample holder device.

[0024] The invention will now be explained in more detail using exemplary embodiments and with reference to the drawings. The drawings show: Fig. 1A,B a sample holder device according to the invention in a first embodiment with clamped sample in a perspective view from above ( Fig. 1A) and the positioning of the sample on the depth stop device schematically from the side ( Fig. 1B), Fig. 2A-C a base body according to a second embodiment, for use with a single depth stop device, in a perspective view from below ( Fig. 2 A), from above ( Fig. 2 B) and from the side ( Fig. 2 C) and Fig. 3A-C two attachment elements for mounting on the base body according to the Fig. 2A-C in perspective view ( Fig. 3A), from below ( Fig. 3 B) and from the side ( Fig. 3 C).

[0025] Fig. Figure 1A shows a sample holder 1, by means of which a sample 50 of a material to be examined can be held without embedding and ground and / or polished by means of a grinding device or polishing machine. The sample holder 1 comprises a base body 10 aligned with respect to a central axis M. The base body 10 has a shape that allows it to be inserted into the grinding device, particularly in a form-fitting manner. For example, the base body 10 shown is cylindrical, with its basic shape symmetrical about the central axis M. The base body 10 has a circumferential surface 11 that runs completely around the axial lower part and partially around the axial upper part, a top surface 12, and a bottom surface 13 opposite the top surface 12. For high wear resistance, the base body 10 can be made of metal, in particular steel. A favorable alternative material for simple manufacturing is plastic.

[0026] The base body 10 comprises a recess 15 formed in its upper surface 12. In this example, the recess 15 is elongated and formed as a rectangular groove in cross-section, open on both sides adjacent to the circumferential surface 11. The recess 15 is formed symmetrically in the base body 10 such that a central longitudinal plane E of the groove lies on the central axis M. Alternatively, the groove can be offset with its central plane M such that a central plane of the specimen 50 (with a thickness of, for example, 2–3 mm) lies approximately on the central axis M when clamped (not shown here). The groove has a bottom 152 oriented orthogonally to the central axis M and two side walls 151, 151' oriented parallel to the central longitudinal plane E and the central axis M, respectively (see figure). Fig. 2A, B). Adjacent to the opening of the recess 15, the upper surface 12 is formed by the upper surface 121 of the base body 10, which is oriented orthogonally to the central axis M. A sample receiving chamber 16 is formed in the recess 15, in particular between a clamping element 32, which is planar parallel to the central longitudinal plane E, and the side wall 151', into which the sample 50 to be ground can be inserted or is inserted. For fastening, the sample 50 is detachably clamped by means of a clamping device 30.

[0027] How Fig. As shown in Figures 2 A to C in more detail, fastening and guide structures are incorporated into the base body 10. Specifically, threaded bores 17, oriented perpendicular to the side wall 151, are provided in the base body 10; two are shown here as an example. The threaded bores 17 open from the circumferential surface 11 into the side wall 151 and serve to accommodate clamping elements 31 of the clamping device 30. Furthermore, at least one guide 14, in particular designed as a threaded bore, for guiding a depth stop device 40 is incorporated into the base body 10 (see Figure 2 A to C). Fig. 2 A to C), which extends from the underside 13 to the base 152. Furthermore, the base body 10 has recesses 18 on the upper side 12 for attaching mounting elements 20 (see Fig. 2B), two of them on each side of the depression as an example.

[0028] On the upper surface 121, two planar mounting elements 20 are detachably arranged, which are in the Fig. 3A to 3C are shown separately. With the assembled sample holder device 1 according to Fig. In 1A and B, the mounting elements 20 lie flat with their undersides 23 on the top surface 121 of the base body 10 and, for example, border the recess 15. Thus, the two mounting elements 20 leave the opening of the recess 15 unobstructed. Opposite the undersides 23, a grinding surface 21 of the mounting element 20 is formed.

[0029] For the detachable fastening of the mounting elements 20 to the base body 10, engagement elements 24 are used; in this case, two are used per mounting element 20 to ensure a secure and uniform fastening. The engagement elements 24 are integrally formed with the mounting elements 20, in this example cylindrical, and project beyond their undersides 23. The engagement elements 24 form pin-like projections with, for example, circular outer circumferential contours, which are engaged by means of an interference fit into the recesses 18 with complementary inner circumferential contours on the upper surface 12 of the base body 10 (see Figure 1). Fig. 2 B) intervene. This type of fastening, similar to the interlocking principle of building blocks, allows the attachment elements 20 to be easily attached to the base body 10 and, if necessary, especially after a grinding process, e.g., using a gripping tool such as pliers or tweezers. Alternatively or additionally, the attachment elements 20 could be fastened by means of a detachable click connection with elastically deformable engagement elements as connecting structures to increase security against the attachment elements 20 falling out (not shown here). For ease of handling, it can be advantageous if the attachment elements 20 are made of plastic. This material offers both cost and manufacturing advantages, with injection molding or 3D printing processes being applicable, for example. It is also conceivable to adapt the material of the attachment elements 20 to the sample material (e.g., with regard to hardness or...).(of the grinding resistance), in order to optimize the grinding result. The attachment elements 20 can also be made of metal and / or ceramic.

[0030] To ensure good distribution of the contact pressure during the grinding process, the mounting elements 20 are designed with a large surface area. In this example, an outer contour 22 of the mounting elements 20 corresponds essentially to an outer contour of the top surface 121, so that the top surface 121 is at least substantially completely covered by the mounting elements 20. Thus, the total surface area of ​​the mounting elements 20 corresponds essentially, e.g., at least 90%, to the surface area of ​​the top surface 121. During the grinding process, the grinding surfaces 21 of the mounting elements 20 form a (grinding) plane with the specimen 50. The large surface area of ​​the mounting elements 20 advantageously results in a large total surface area, which reduces the pressure, i.e., the force applied by the grinding device per unit area. Therefore, the pressure on the specimen 50 can be kept comparatively low, thus preventing damage to the specimen (e.g.,This prevents crushing, "crumbling," etc. Axial adjustability of the mounting elements 20 is neither provided nor required. To absorb the contact pressure, the upper surface 121 is designed to be at least twice the size of the opening, e.g., 2.9 times larger.

[0031] The mounting elements 20 preferably have a minimum thickness d between 0.5 mm and 5 mm, e.g., between 1 mm and 2 mm, before the first grinding operation. In this range, sufficient wear material is advantageously obtained during a single grinding operation. In particular, unevenness and / or protrusions of the specimen beyond the grinding plane, which can also occur during clamping, can be compensated for by a "grinding" to initially produce a uniform grinding plane.

[0032] For the axial positioning of the sample 50, the axially adjustable depth stop 40 is provided in the sample receiving chamber 1. The depth stop 40 allows for relatively precise axial pre-positioning of the sample 50 for the grinding process. The sample 50 is positioned such that one side to be ground is axially approximately at the level of the grinding surfaces 21 of the mounting elements 20. This essentially prevents any macroscopic protrusion of the sample 50 beyond the grinding surfaces 21 of the mounting elements 20, which could lead to damage (e.g., breakage) of a sensitive sample. The depth stop 40 enables such pre-positioning, particularly for samples 50 of different heights, up to a maximum depth equal to the depth of the sample chamber (defined by the height of the side walls 151, 151'), plus the thickness d of the mounting elements 20.The sample holder device 1 can thus be advantageously used for samples of 50 different sizes.

[0033] The depth stop device 40 comprises at least one depth stop element 42 with a depth stop surface 41 on which the specimen 50 rests. Optionally, several depth stop elements 42 or depth stop surfaces 41 may be included, as for example in Fig. 1A, B, be present, with sample 50 in Fig. 1A, B, due to their narrow width, only rest on a depth stop surface 41 (see schematic detail in Fig. 1B) and the second depth stop surface 41 is unused. In this case, the depth stop elements 42 are formed in an easy-to-assemble and material-saving design by one, two, or three (not shown here) screws. The depth stop surfaces 41 are formed by the end faces of the screws. The screws are guided from the underside 13 of the base body 10 by the axially directed guides 14 formed by threaded bores. Thus, the depth stop device 40, with respect to the position of the depth stop surface 41, can be easily adjusted axially as needed, depending on the sample dimension, by turning the screw. The guide 14, or the depth stop device 40, is preferably designed such that a smooth underside 13 of the base body 10 is obtained, without any protrusion of the depth stop device 40.

[0034] For this purpose, the screw(s) can advantageously be designed as a setscrew or have a countersunk head. This allows pressure to be applied unhindered to the underside 13 during the grinding process by means of a pressure device of the grinding unit.

[0035] The clamping device 30 has at least one clamping element 31 by means of which a clamping force can be applied to hold the specimen 50. In this case, the clamping elements 31 are formed by two screws, each of which is adjustable orthogonally to the central axis M via the threaded bores 17. For flexible and secure support of different specimen shapes (with different widths), three screws, for example, would also be possible. In addition, the clamping device 30 has a flat clamping element 32 in the form of a clamping jaw, which can be attached to the base body 10 (e.g., to the clamping elements 31) either loosely or pre-assembled before clamping the specimen 50. The specimen receiving space 16 is formed between the clamping element 32 and the side wall 151', and its width is adjustable by means of the clamping element 32 and the clamping elements 31.By means of the clamping element 32, the specimen 50 can be clamped or clamped against the side wall 151' as the counter surface by applying a clamping force via the clamping means 31. The clamping element 32 can, for example, have approximately the surface dimensions of one of the side walls 151, 151'. This allows even comparatively large specimens 50, e.g., with a surface area corresponding to the side wall 151', to be clamped over their entire surface. The clamping element 32 is designed to be at least such that the clamping pressure is distributed over the entire surface of the specimen 50 in order to prevent damage to the specimen 50, in particular crushing. For example, the width of the clamping element 32 corresponds to the width of the specimen 50, and the clamping element 32 is preferably at least as high as the recess 15. If the clamping element 32 protrudes beyond the recess 15, it can be ground down during the grinding process. Furthermore, the clamping element 32 is preferably made of a material hard enough to withstand the force of the clamping element 32. B.The clamping device 30 is made of steel and designed to transmit the clamping pressure of the clamping device 31 to the specimen 50. The clamping force can thus be applied orthogonally to the contact force of the grinding device. Such a design of the clamping device 30 also allows the clamping of small-volume specimens 50 (dimensions of all three dimensions < 10 mm, for example 7 mm x 5 mm x 3 mm).

[0036] In addition to the mounting elements 20, the combination of the existing adjustable depth stop device 40 with the clamping device 30, which applies a clamping force orthogonal to the contact force during grinding, is particularly advantageous for grinding sensitive specimens 50. In this way, the compressive force acting on the specimen 50 during the grinding process can be compensated both by the clamping force and by the force applied axially, parallel to the contact force, via the depth stop device 30. Thus, the contact force is distributed across various contact points, preventing a high localized force acting on the specimen 50 that could lead to its destruction. Furthermore, the large surface area of ​​the mounting elements 20 results in a comparatively low contact force on the specimen 50 that needs to be compensated during the grinding process.

[0037] In the in the Fig. 1 and Fig.In the two illustrated embodiments, the depth stop device 40 defines the minimum width of the sample holding chamber 16 by having the longitudinal side(s) of the depth stop elements 42 act as a stop for the clamping element 32. To obtain a smaller minimum width and to provide a large contact area for the depth stop surface 41 adjacent to the side wall 151', the depth stop elements 42 are recessed approximately halfway into the side wall 151. To eliminate the width limitation, the flat clamping element 32 could have a recess on its longitudinal side facing the depth stop surface, into which the depth stop elements 42 can be axially adjusted (not shown here).

[0038] For the grinding process, the specimen 50 is first inserted into the specimen holding chamber 16 between the side wall 151' and the clamping element 32, whereby the clamping element 32 initially applies no or only a slight clamping force, allowing the specimen 50 to remain movable. The depth stop device 40 is then axially adjusted so that the side of the specimen 50 to be ground is positioned approximately, macroscopically, at the level of the grinding surfaces 21 of the mounting elements 20. Optionally, a guide surface can be used for this purpose. This guide surface is placed on the grinding surfaces 21, and the specimen 50 is adjusted vertically using the depth stop device 40 until it is also in contact with the guide surface. The side of the sample 50 to be ground can be positioned below the grinding surfaces 21 of the mounting elements 20, but within the thickness d of the mounting elements 20, so that a uniform grinding plane of the sample 50 and the mounting elements 20 can be produced.To prevent damage to the sample 50, macroscopic protrusion of the sample 50 beyond the grinding surfaces 21 must be avoided. Following axial positioning, a clamping force is applied to the sample 50 by means of the clamping device 30. This, in conjunction with a force applied by the depth stop device 40, ensures secure positioning of the sample 50 during the grinding process. The sample holder 1 is then inserted into the grinding device such that the grinding surfaces 21 of the mounting elements 20 come into contact with the grinding wheel, and the contact pressure for the grinding process is applied by means of the grinding device. In the subsequent grinding process, a macroscopically flat grinding surface is produced in a first grinding step using a coarse grinding wheel, i.e., with a coarser grit than in the subsequent grinding steps.In this process, the grinding surfaces of the mounting elements 21 and the surface of the sample 50 to be ground create a macroscopically flat (ground) plane upon which the contact pressure is applied. Any inaccuracies in the insertion of the sample 50, such as slight tilting, etc., or unevenness in the sample surface are compensated for by this process step. This process step can be accelerated by using relatively soft mounting elements 20, e.g., made of plastic. In a second grinding step, and possibly subsequent grinding steps, a fine grinding can then be carried out, resulting in a microscopically flat plane that enables microscopic examination of the microstructure of the sample 50.

[0039] After the grinding process, the sample 50 can be easily removed from the sample holder 1 by releasing the clamping device 30. Depending on the grinding depth, the mounting elements 20 can or must be replaced for the next grinding process. The mounting elements 20 are therefore consumables. However, by using materials such as plastic, they can be manufactured cost-effectively and are easy to install and remove.

[0040] With the sample holder device 1 according to the invention, even small-volume and / or sensitive, as well as porous samples 50 can be prepared in a grinding process for material research purposes for the investigation of the microstructure.

Claims

[1] Sample holder device (1) for a grinding device, comprising a base body (10) aligned with respect to a central axis (M), which includes a recess (15) open towards a top (12) with a sample receiving space (16), and a clamping device (30) for clamping a sample (50) in the sample receiving space (16), wherein at least one mounting element (20) for mounting on a grinding wheel during the grinding process is detachably arranged on the top (12) of the base body (10), characterized by , that in the sample receiving chamber (16) an axially adjustable depth stop device (40) with at least one depth stop surface (41) for axial positioning of the sample (50) is provided, that the clamping device (30) has clamping means (31) and a planar clamping element (32) which are arranged such that a clamping force can be applied to the specimen (50) orthogonally to a flat side wall (151') of the recess (15), that the at least one mounting element (20) is designed to be large-area, wherein an upwardly directed grinding surface (21) of the mounting element (20), facing away from the top surface (12), is larger than 200% of a grinding surface of the sample (50), that in the plane of the top surface (12) of the base body (10) the ratio of a top surface (121) of the base body (10) to the size of the opening of the recess (15) is at least 2 : 1 and that, when assembled, the mounting element (20) covers at least 70% or at least 90% of the top surface (121). [2] Sample holder device (1) according to claim 1, characterized by, that the depth stop surface (41) is formed by the end face of a screw or by a surface element. [3] Sample holder device (1) according to one of the preceding claims, characterized by , that at least two mounting elements (20) are present which are arranged in such a way that they leave out the opening of the recess (15). [4] Sample holder device (1) according to one of the preceding claims, characterized by that the mounting element(s) (20) is / are made of a material softer than the sample (50), in particular of a plastic. [5] Sample holder device (1) according to any one of the preceding claims, characterized by that the mounting element(s) (20) has / have a thickness (d) of 0.5 mm to 5 mm, preferably of 1 mm to 4 mm, e.g. between 1 and 2 mm, before the first grinding process. [6] Sample holder device (1) according to one of the preceding claims, characterized bythat the mounting element(s) is / are detachably attached to the base body by means of a press fit or a positive locking connection, e.g. a click connection. [7] Sample holder device (1) according to one of the preceding claims, characterized by , that the planar clamping element (32) has a recess on a side pointing towards the depth stop surface (41), into which the depth stop surface (41) can be axially adjustable parallel to the central axis (M). [8] Sample holder device (1) according to one of the preceding claims, characterized by , that the depression (15) is elongated and is open at least on one side towards the circumferential side of the base body (10). [9] Method for producing a microscopically flat plane on a sample (50) using a grinding device and a sample holder device (1), in particular according to one of the preceding claims, wherein a. the sample (50) is inserted into a sample receiving chamber (16) of the sample holder device (1), wherein the sample (50) is positioned macroscopically at axial height or below a grinding surface (21) of a mounting element (20) with one side to be ground. b. subsequently, a clamping force is applied to the specimen (50) by means of a clamping device (30), which, if necessary in conjunction with another force, ensures a secure positioning of the specimen (50) during a grinding process, c. subsequently the sample holder device (1) is inserted into a grinding device in such a way that the grinding surface (21) of the mounting element (20) comes into contact with a grinding wheel of the grinding device and d. subsequently, in one or more grinding steps, a grinding is carried out on the sample (50) to obtain a microscopically flat surface for microscopic investigations of the microstructure. [10] Method according to claim 9, characterized by , that between steps c. and d. a first grinding step involves a rough grinding, whereby a macroscopically flat grinding surface is produced using a coarser grinding wheel than in the subsequent grinding steps. [11] Mounting element (20) designed to be used in a sample holder device (1) according to any one of claims 1 to 8. [12] Base body (10) designed to be used in a sample holder device (1) according to any one of claims 1 to 8.

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