CN115666849A

CN115666849A - Laboratory disc grinding device, method, replacement grinding disc and application of grinding disc

Info

Publication number: CN115666849A
Application number: CN202180035312.4A
Authority: CN
Inventors: 罗伯特·霍尔
Original assignee: Atm Ginnis Ltd
Current assignee: Atm Ginnis Ltd
Priority date: 2020-05-15
Filing date: 2021-05-10
Publication date: 2023-01-31
Also published as: US20230182256A1; WO2021228753A1; DE102020113324A1; JP2023528236A; EP4149719A1

Abstract

The invention relates to a laboratory disk grinding device and a method for the flat grinding of the underside of in particular embedded samples, as well as a replacement grinding disk for a laboratory disk grinding device and the use of a grinding disk in a laboratory disk grinding device, wherein the grinding disk (16) is subdivided into a peripheral annular first surface region (42) and a central second surface region (44) arranged within the peripheral annular first surface region (42), wherein the top surface (62 b) of the carrier disk (62) is coated with an abrasive material (46) only in the peripheral annular first surface region (42), so that a peripheral annular first surface region (42) to be ground and a passive central second surface region (44) are formed.

Description

Laboratory disc grinding device, method, replacement grinding disc and use of a grinding disc

Technical Field

The invention relates to a laboratory-sized material removal device for grinding a ground sample in the form of a laboratory disk grinding device, a method for flat grinding a bottom surface of a ground sample, in particular an embedded sample, and a replacement grinding disk for a laboratory disk grinding device and the use of a grinding disk in a laboratory disk grinding device.

Background

In order to carry out material investigations of samples in metallography, smaller sample pieces are usually embedded in a cylinder made of plastic material. The diameter of such an embedded sample is for example 40mm. Subsequently, the embedded sample is ground flat and optionally polished in order to carry out material investigations, such as hardness test measurements or texture analyses, on the ground flat and optionally polished surface of the material sample. For the flat grinding and, if appropriate, polishing of embedded metallographic specimens, laboratory disk grinding apparatuses with rotating grinding disks are typically used, which are known, for example, by the trade names Saphir and Rubin of ATMQness GmbH, seewww.qatm.com. Usually, such laboratory disk grinding apparatuses are designed as combined grinding and polishing apparatuses, i.e. laboratory disk grinding apparatuses may also be equipped with polishing disks to show an additional polishing function. Such laboratory disk grinding devices are therefore typically used in material testing, in particular in hardness testing or texture analysis, for the surface grinding and, if appropriate, polishing of the underside of embedded specimens.

Such laboratory disc milling apparatus are either single spindle or multi-spindle. A manual laboratory disc mill apparatus has primarily a housing with a trough, a drive motor and a grinding disc. In these simple devices, the embedded sample can be pressed and ground by hand. In addition, automatic grinding apparatuses also have an apparatus head, sometimes referred to as a polishing head, having a pressing column in which a rotating sample holder can be mounted. The sample can be loosely located in the sample holder and pressed against the grinding disc by means of individual pressing pins (single sample pressing pressure), or the sample is fixedly clamped in the sample holder and the entire sample holder is pressed against the grinding disc (central pressing pressure).

The grinding disks used in such laboratory disk grinding apparatuses are typically embodied to be full-surface, that is to say that the abrasive material with a specific particle size and a specific dispersion is distributed over the entire surface of the grinding disk, possibly in a specific pattern, from the inside to the outside.

However, the peripheral speed of the grinding disc decreases towards the centre. As a result of the decrease in the peripheral speed,

towards the center of the disk, the pressure on the sample increases. At the center of the disc there is typically no work, since the circumferential speed is equal to zero and therefore no material is removed. Thus, the outer region of the disc is mainly used, and the inner region is not used. After long use, this leads to different wear, so that the grinding disk is no longer flat after long use, which in turn has an adverse effect on the flatness of the sample which is in principle intended to be achieved.

This adverse effect is counteracted by regularly sanding the grinding disc, usually by hand, with a grinding stone, but this disadvantageously results in additional work. Furthermore, this wastes abrasive material, resulting in unnecessary costs.

These effects are even more problematic in the case of automated laboratory disk milling apparatuses, in which one or more samples are fixed in sample holders which are automatically pressed against a grinding disk by means of a pressing column rotationally fixed on the apparatus head. In this case, the samples are typically always ground on the same radius of the grinding disk, which leads to an uneven wear of the grinding material on the grinding disk to a particular extent, i.e. in the outer annular region, in which the sample or samples are mainly ground. Since the sample or, in the case of a plurality of samples, all the samples, despite their rotation, remain approximately in the same radial interval in the radial direction, it is possible, during long-term use, for the height difference of the grinding surface, i.e. of the grinding body between the radially outer region and the central region of the grinding disk, to occur, since less or even no wear of the grinding material is caused in the central region.

If such an unevenly worn grinding disc is not periodically ground with a grinding stone, it may even cause the abrasive to form a real step at a certain radius, which may lead to a principally undesired rounding of the lower outer edge of the embedded sample.

Disclosure of Invention

It is therefore an object of the present invention to provide a laboratory disc grinding apparatus, a method, a replacement grinding disc and the use of a grinding disc, which avoid or at least reduce the above mentioned disadvantages.

Another aspect of the object of the invention is to provide a laboratory disc grinding apparatus, a method, a replacement grinding disc and the use of a grinding disc, wherein on the one hand the necessity of grinding of the grinding disc is dispensed with or at least reduced, and wherein, nevertheless, the ground bottom surface embedded in the sample has a high degree of flatness, wherein in particular rounding at the edges of the sample is avoided or at least reduced, while the service life of the grinding disc is long.

The object of the invention is achieved by the subject matter of the independent claims. Preferred embodiments are the subject of the dependent claims.

The invention relates to a laboratory-sized disc grinding device having a rotating grinding disc for the flat grinding, in particular for the bottom surface of embedded metallographic specimens, wherein the laboratory disc grinding device can also be designed as a combined grinding and polishing device. It comprises a device housing with a grinding-disc receiving disc and a drive motor by means of which the grinding-disc receiving disc is rotated. The rotational speed of the grinding disc is preferably adjustable and may be, for example, 30min ^-1 And 600min ^-1 And (4) adjusting.

An especially thin grinding disk can be attached, for example, to the grinding disk receiving disk, which essentially consists of a carrier disk and an abrasive layer in the form of abrasive grains or abrasive particles bonded to the carrier disk as an abrasive. The bonding of the abrasive particles is preferably carried out by a synthetic resin bonding or a metal bonding, such as nickel bonding, in which the abrasive particles are embedded.

The carrier disk of the grinding disk has a top side and a bottom side and is detachably fastened, for example adhesively fastened, to the grinding disk receiving disk by means of the bottom side, in order to be able to simply replace the grinding disk as a consumable material after a corresponding wear or for grinding with a changed grain size. For this purpose, the grinding disk can be attached to the grinding disk receiving disk, for example magnetically, i.e. by magnetic attachment of the carrier disk to the grinding disk receiving disk, or by a carrier disk having an adhesive bottom surface, for example with a gel-like surface coating. The grinding disk is here in particular significantly larger than the sample to be ground flat, the diameter of which is typically in the range from 30mm to 60 mm.

According to one aspect of the invention, the grinding disk is divided into a peripheral annular first surface region and a central second surface region located within the peripheral annular first surface region, wherein the top surface of the carrier disk is only covered with abrasive grains as an abrasive material in the peripheral annular first surface region, thereby forming a peripheral annular first surface region to be ground and a passive, non-ground central second surface region. In other words, the grinding disk has a peripheral annular region covered with abrasive material, which is to be ground, and a blank position in the annular inner region, in which free position there is no abrasive material, i.e. although there is a carrier disk of the grinding disk in the passive, non-ground central second face region, it is not substantially covered with abrasive particles as abrasive material. Alternatively, it is also conceivable to additionally remove the grinding-disk receiving disk and the carrier disk in the non-ground central second surface region and to provide an outflow opening for the coolant in the grinding-disk receiving disk. The abrasive layer on the carrier disc, i.e. the active grinding side of the grinding disc, is therefore designed as an annular surface and surrounds the exposed, non-grinding central region of the carrier disc. The abrasive layer is correspondingly annularly configured with an indentation in the center about the rotational axis of the grinding disk.

The radial width of the abraded peripheral annular region or of the annular abrasive layer is preferably adapted to the dimensions of the sample or samples in such a way that the sample or samples with their edge regions extend, in particular permanently or at least regularly, radially inwards beyond the abraded peripheral annular region, so that no surface regions remain in the central region of the grinding disc which do not simultaneously, in particular not permanently or at least regularly, act when the sample or samples are abraded. In other words, the entire surface of the abrasive layer is used to abrade the bottom surface of the one or more samples without the areas of the abrasive layer not traversed by the one or more samples. In other words, the diameter of the non-ground central second face area is large enough that the sample or samples permanently or at least regularly go radially inwards into the passive, non-ground central second face area.

Different wear of the abrasive material or of the abrasive layer, in particular in the central inner region of the grinding disk, can thus advantageously be avoided, since there is preferably no abrasive material at all.

Thereby achieving a synergistic dual benefit. On the one hand, it is possible to dispense with or at least significantly reduce the regular grinding of the grinding disc and nevertheless ensure a flat grinding result for the bottom surface of the sample or samples, even if the grinding disc has reached a certain degree of wear. On the other hand, waste of abrasive material at locations where the peripheral speed of the grinding disc is inherently too small to obtain optimum grinding results can be avoided or at least reduced.

Preferably, uneven wear of the grinding material can additionally also be avoided on the radial outside of the grinding disk, in that the one or more samples project radially outward beyond the peripheral annular region in which grinding takes place, i.e. project or protrude radially outward beyond the peripheral annular region in which grinding takes place.

In the annular region or annular abrasive layer of the outer periphery of the grinding, the abrasive grains are bonded to the carrier disc by means of a binder as an abrasive having a specific particle size and a specific dispersibility. As the adhesive, for example, epoxy resin or nickel can be used. As the abrasive, for example, diamond in the form of diamond particles having a desired particle size, which are industrially produced, is used, and the diamond particles are incorporated into a synthetic resin having a desired hardness (soft, medium, and hard). Preferably, the abrasive particles are printed as powder, for example diamond powder, with a printing method with a synthetic resin onto the surface of the carrier disc and are locally bonded there. Thus, the abrasive particles are preferably printed with a binder in a predefined pattern in the peripheral annular first face region of the abrasive. Screen printing methods are particularly suitable for this. Alternatively, the abrasive particles can also be bonded to the carrier disk by means of a metal bond, for example a nickel bond.

In this way, a surface of the annular abrasive layer is formed in the cross section of the grinding disk, more precisely by abrasive grains embedded in a binder, which in the peripheral annular first surface region to be ground define a common, annular, first surface to be ground of the grinding disk. The carrier disk of the grinding disk forms the central, non-abrasive second surface of the grinding disk in the passive, non-abrasive central second surface region, since the central second surface region of the carrier disk is not covered with abrasive grains or because there is a free abrasive layer. Thus, in the new, unworn state of the grinding disc, the common ring-ground first surface of the grinding disc is higher than the central, non-ground second surface of the grinding disc, so that on the inner radius of the ring-shaped abrasive layer a height difference or step is formed between the common ring-ground first surface and the central, non-ground second surface, and one or more samples enter the passive, non-ground central second face region and are axially spaced therefrom by the height difference.

The height difference of the steps or the thickness of the abrasive layer between the common annular first surface to be abraded or the annular surface of the abrasive layer and the central, non-abrasive second surface can, depending on the abrasive disc, be, for example, between 50 μm and 5mm, preferably between 100 μm and 3mm, preferably between 200 μm and 1.5 mm. Suitable particle sizes for the peripheral annular first face region to be milled have a particle size of 3 μm, 6 μm, 15 μm, 30 μm, 60 μm, 125 μm, or 250 μm or a particle size of 80, 120, 180, 240, 320, 600, 800, 1000, 1200, 2500, wherein the particle size corresponds to 25.4mm (1 inch)/particle size. For example, the particle size is 25.4mm/1000=0.025mm in the case of a 1000-particle size, or 25.4mm/80=0.32mm in the case of an 80-particle size. Particle sizes of less than 80 are quite uncommon in laboratory disc mill equipment, so the maximum particle size is preferably about 0.32mm or 0.25mm.

In the peripheral annular first surface region to be abraded, the abrasive grains are preferably bonded to the top side of the carrier disc with adhesive in a plurality of layers, preferably in 3 to 200 layers, preferably in 5 to 100 layers, so that on average about 3 to 200, preferably about 5 to 100, abrasive grains are bonded axially one above the other in the abrasive layers of the plurality of layers.

It is further preferred that the abrasive layers of the multilayer are designed to be self-sharpening, for example, so that already dulled abrasive particles, for example diamond particles, are detached during the grinding process, whereby new abrasive particles, for example diamond particles, from the layer lying therebelow automatically penetrate into the surface.

This has the advantage on the one hand that the grinding discs in laboratory disc grinding apparatuses have a long service life and that a large number of embedded samples can be ground one after the other before the grinding disc has to be replaced. On the other hand, the combination of a grinding disk, in particular of a plurality of layers of abrasive grains removed one above the other, with a recess in the abrasive layer in the inner region of the grinding disk offers a synergistic advantage, since without the invention, in particular in the case of a multi-layer self-sharpening grinding disk, the height differences which occur are particularly great due to the strongly differing wear.

In other words, the height difference between the peripheral annular first region, on which the grinding takes place, and the passive, non-ground central second surface region preferably does not correspond to the size of the abrasive grains, but is rather significantly greater than the size of the abrasive grains, since the bond, preferably a synthetic resin bond, with the diamond particles is applied in a plurality of layers, for example by means of a screen printing method, and therefore a height difference of, for example, up to 1mm can also be applied with smaller grain sizes. Thus, even if the abrasive particles dulle relatively quickly, the life of the abrasive disc is significantly increased. As described above, in the multilayer combination of abrasive grains, when the abrasive grain becomes dull, it comes off due to high cutting force with the base body and new and still sharp abrasive grains located thereunder appear on the surface and exert their abrasive action. A long service life can thereby be achieved.

The grinding disc is preferably (right) round and/or has an outer diameter of between 100mm and 500mm, preferably between 150mm and 400mm, preferably 300mm +/-50mm.

The peripheral annular first surface area or annular abrasive layer to be abraded preferably has an inner diameter D _ i and an outer diameter D _ a, wherein half the difference between the inner diameter D _ i and the outer diameter D _ a defines the radial width B _ r of the annular abrasive layer and has a value of between 240mm and 20mm, preferably between 180mm and 25mm, preferably 30mm +/-10mm or 125mm +/-50mm. For abrading a single sample, the radial width B _ r of the annular abrasive layer may be 30mm +/-10mm or 5% to 50% narrower than the diameter of the embedded sample, and in the case of a sample holder with multiple samples, the radial width B _ r of the annular abrasive layer may be 125mm +/-50mm or between 150% and 400% of the diameter of the single embedded sample.

According to a preferred embodiment, the abrasive peripheral annular first face zone or annular abrasive layer has an inner diameter D _ i and an outer diameter D _ a, wherein inner diameter D _ i corresponds to the outer diameter of the passive non-abrasive central second face zone, inner diameter D _ i is preferably between 20mm and 450mm, preferably between 30mm and 300mm, preferably 50mm +/-30mm for a sample holder with multiple samples, or 250mm +/-50mm for a single sample, and/or outer diameter D _ a is preferably between 100mm and 500mm, preferably between 150mm and 400mm, preferably in the range of 300mm +/-50mm.

The carrier plate is preferably designed as a particularly rigid plate. Sufficient rigidity of the carrier disc is advantageous for critical grinding parameters in laboratory disc grinding apparatuses. The plate is preferably a metal plate, but it may also be a plastic plate. Preferably, the thickness of the plate is between 0.1mm and 3 mm. For example a metal plate with a thickness of 0.5mm is suitable. Magnetizable metal plates, for example magnetizable steel plates, are particularly suitable, since they can be directly magnetically attached to the grinding-disc receiving disc if the latter comprises a magnet.

The abrasive particles are preferably diamond particles, which in turn has a positive effect on the service life of the grinding disk.

The abrasive particles are preferably bonded to the carrier disc by means of a synthetic resin bond. Alternatively, nickel bonding may be considered. Here, the abrasive particles are embedded in a binder. For example, the combination is performed by a screen printing method.

The abrasive or diamond particles may even be bonded directly to the plate using an adhesive. Alternatively, the abrasive disc may include an intermediate layer of fabric to which abrasive or diamond particles are bonded by an adhesive. The latter may have production technical advantages. In this case, the fabric substrate together with the abrasive layer forms a flexible abrasive pad which is then in turn affixed to the plate such that the plate together with the intermediate layer of fabric forms a carrier disc in order to obtain a rigid abrasive disc.

According to a preferred embodiment, the grinding disc is provided with an adhesive with which the grinding disc is detachably attached to the grinding disc receiving disc at the bottom surface. The attachment can be achieved, for example, by means of magnetic forces or a gel-like attachment layer. The user can thus simply and comfortably replace the grinding disc, for example for the purpose of changing the grain size or when the grinding disc has reached the end of its service life.

Preferably, the grinding disc contains the disc and therefore the grinding disc rotates in a collecting tank, which collects the grinding grits and possible cooling liquid. The grinding disk can thereby be cooled with a cooling fluid, for example water, and the grinding particles are washed away.

According to a preferred embodiment, the laboratory disk grinding device comprises a preferably exchangeable sample holder, which can be configured, for example, as a plate for placing a plurality of samples or as a holder for a single sample, wherein a sample or a plurality of samples are loaded into the sample holder and pressed by the sample holder onto the grinding disk by means of a single pressing pressure or by means of a central pressing pressure, respectively. At a single compaction pressure, one or more samples are simply placed into the sample holder, and at a central compaction pressure, one or more samples are fixedly clamped. Furthermore, in addition to the rotation of the grinding disk, the sample holder rotates with the inserted sample or inserted samples, the edge region of the sample or samples during the grinding process and during the double rotation of the grinding disk and the sample holder in the opposite or in the same direction radially on the inside and, if necessary, on the outside, radially beyond the peripheral annular first surface region or annular abrasive layer which is to be ground and radially on the inside into the passive, non-ground central second surface region. This ensures that no abrasive material is present in the central inner region of the grinding disc, which is not uniformly worn away by the sample or samples.

In other words, i) in the case of a single sample, the sample defines an outer diameter, and the sample projects radially with its outer diameter radially inwards and possibly outwards beyond the abraded peripheral annular first face area or annular abrasive layer during the abrading process, and ii) in the case of a sample holder inserted with a plurality of samples, the entirety of the sample defines an overall outer diameter based on the rotation of the sample holder, and the overall outer diameter projects radially inwards and possibly outwards beyond the abraded peripheral annular first face area or annular abrasive layer and into the passive, non-abraded central second face area during the abrading process.

According to a preferred embodiment of the invention, the laboratory disk grinding apparatus is configured as an automated laboratory disk grinding apparatus and comprises an apparatus head with a pressing column for fixing the sample holder. The pressing column, on the lower end of which the sample holder for inserting one or more samples is fixed, is driven by a rotary drive and bears vertically against the grinding disc by means of a linear drive, for example a spindle drive. The pressing column automatically presses the sample inserted in the sample holder against the grinding disc with a predetermined pressing force, in order to thus carry out the grinding process with a predetermined pressing force, wherein a single pressing pressure or a central pressing pressure can be used. Under a single pressing pressure, each sample is pressed against the grinding plate individually by means of a single pressing pin and is not fixedly clamped in the sample holder, but is carried along, but is axially movable in the sample holder. The sample is clamped in the holder in a fixed manner under a central pressing pressure, for example by means of radial clamping screws. The rotation of the pressing post and/or the pressing force acting on the grinding disc may be preselected by the user by means of a user interface, and the rotation and/or the pressing force caused by the pressing post is then automatically controlled by the control device. In this case, the grinding takes place in a double rotation, i.e. in the same or opposite direction, with the rotation of the grinding disk and the rotation of the sample holder, which achieves a particularly uniform grinding result.

The sample holder can be configured, for example, as a disk-shaped holder, in which a plurality of samples are inserted alongside one another, but it can also be configured as a gripper, which in particular grips and fixes a single sample. Such a clamp as a sample holding device can be configured, for example, as a three-finger clamp.

The laboratory disk grinding apparatus preferably has at least one coolant nozzle for spraying a coolant onto the grinding disk. The cooling liquid is then usually collected in a collecting tank and can be discharged together with the grinding grits via a discharge opening. In particular when the laboratory disk grinding device is configured as a combined grinding and polishing device, a plurality of nozzles can be provided, so that diamond suspensions of different particle sizes or polycrystalline or single-crystal particle sizes can also be applied during polishing. Furthermore, laboratory disk milling apparatuses can be designed both in manual and in automatic versions as single-or multi-spindle, i.e. with one or more grinding stations arranged next to one another, each with a grinding disk receiving disk.

The abraded peripheral annular first face region or annular abrasive layer has an inner diameter D _ i and an outer diameter D _ a, wherein half the difference between the inner diameter D _ i and the outer diameter D _ a defines the radial width B _ r of the abraded peripheral annular first face region and annular abrasive layer. The radial width B _ r is preferably adapted i) to the diameter of the sample in the case of a single sample, or ii) to the diameter of the entire sample in the case of a plurality of samples arranged next to one another. In this case, preferably, i) in the case of a single sample, the radial width B _ r of the ground peripheral annular first face region is selected such that the diameter of the sample protrudes inwardly an inner diameter D _ i and/or outwardly an outer diameter D _ a, in particular permanently or temporarily due to radial displacements or oscillations of the sample rotating during the grinding process, and ii) in the case of a sample holder comprising a plurality of samples inserted side by side, the entirety of the sample defines a total outer diameter D _ g (circular envelope) on the basis of the rotation of the sample holder, and the radial width B _ r of the ground peripheral annular first face region or annular abrasive layer is selected such that the total outer diameter D _ g (circular envelope) protrudes inwardly an inner diameter D _ i and/or outwardly an outer diameter D _ a, and in particular permanently or temporarily due to radial displacements or oscillations of the sample rotating during the grinding process. In both cases, one or more samples can thus extend radially inside and/or radially outside beyond the peripheral annular first face region or annular abrasive layer to be abraded, thereby avoiding abrasive regions without wear. In other words, the grinding disc does not have a portion covered with abrasive material on the one hand and not passed by the sample or samples on the other hand, so that there is no portion on the surface of the grinding disc covered with abrasive material that is not worn by the grinding of the sample or samples.

One aspect of the invention also relates to a method for the flat grinding of the underside of, in particular, embedded samples with a rotating grinding disc, in particular with the laboratory disc grinding apparatus described above. The grinding disk here has a carrier disk and abrasive grains bonded to the carrier disk by means of an adhesive or consists of the same, optionally with a textile intermediate layer, for example, and is significantly larger than the sample to be flat ground. The grinding disc is further divided into a peripheral annular first face area and a central second face area within the peripheral annular first face area, the top face of the carrier disc being covered with abrasive particles as abrasive material only in the peripheral annular first face area, thereby forming a peripheral annular first face area or annular abrasive layer for grinding and a passive non-grinding central second face area. One or more of the samples are inserted into a sample holder, which may also be configured as a sample holder, and the one or more samples are pressed mechanically against the grinding disc when necessary. In addition to the rotation of the grinding disk, the sample holder is also rotated continuously with the one or more samples during the grinding process, and in this case the edge region of the one or more samples extends radially on the inside and possibly on the outside beyond the peripheral annular first surface region or annular abrasive layer of the grinding into the region without abrasive, in particular permanently or by radial oscillation of the sample holder or the samples.

In other words, i) in the case of a single sample, the sample defines an outer diameter, and the sample rotates during the grinding process and with its outer diameter radially overhangs internally or, if necessary, externally the ground peripheral annular first face region or annular abrasive layer, and ii) in the case of a sample holder with a plurality of inserted samples, the entirety of the sample holder and sample defines an overall outer diameter on the basis of the rotation of the sample holder, and the overall outer diameter radially overhangs internally or, if necessary, externally the ground peripheral annular first face region or annular abrasive layer during the grinding process, thereby ensuring a uniform wear of the abrasive over the entire abrasive-covered surface of the grinding disc for a long period of time.

One aspect of the invention also relates to an abrasive disc as a replacement abrasive disc, consisting of a carrier disc and abrasive grains bonded to the carrier disc by means of an adhesive, which are used as abrasive material, for a laboratory disc grinding apparatus for the flat grinding of, in particular, the bottom surface of an embedded sample, as described above, wherein the abrasive disc is significantly larger than the sample to be flat ground, wherein the carrier disc of the abrasive disc has a top surface and a bottom surface, and wherein the abrasive disc can be releasably attached to the abrasive disc receiving disc via the bottom surface, wherein the abrasive disc is divided into a peripheral annular first face region and a central second face region located in the peripheral annular first face region, wherein the top surface of the carrier disc is covered with abrasive grains as abrasive material only in the peripheral annular first face region, thereby forming a peripheral annular first face region or annular abrasive layer on which grinding is performed on the carrier disc, and a passive, non-ground central second face region of the carrier disc.

One aspect of the invention also relates to the use of the replacement abrasive disc in the laboratory disc grinding apparatus.

Drawings

The invention is explained in detail below with the aid of embodiments and with reference to the drawing, in which identical and similar elements have in part the same reference numerals and features of different embodiments can be combined with one another.

It shows that:

figure 1 shows a three-dimensional view of one embodiment of a laboratory disc mill apparatus,

figure 2 shows an enlarged view of the abrasive disc and sample holder of figure 1,

figure 3 shows a cross-section of an embedded sample,

figure 4 shows a top view from above of the abrasive disc with sample holder in figure 2,

figure 5 shows a cross-section along line 5-5 in figure 4,

figure 6 shows a close-up view of area a of figure 5,

figure 7 shows another embodiment of a laboratory disc mill apparatus,

figure 8 shows a schematic cross-sectional view of the sample holder and abrasive disc of figure 7,

fig. 9 shows a three-dimensional view of the device head of fig. 7, without the device head housing,

figure 10 shows a vertical section through the apparatus head of figure 9,

fig. 11 shows a cross-sectional view of uneven wear of a conventional abrasive disc.

Detailed Description

Referring to fig. 1, a laboratory disc mill apparatus 10 has an apparatus housing 12, which in this example is a vertical housing for placement on a laboratory bench. Located above the device housing 12 is a device head 14, which in this example is configured as a cantilever, which extends above the grinding disc 16. The abrasive disc 16 rotates in a collection trough 18 within the device housing 12. A rotating pressing column 20 extends downwards from the device head 14, and at a lower end 22 of the pressing column 20, a sample holder 24, which in the present example is disc-shaped, is fixed by means of a connection column 26 (fig. 2). In this example, six embedded metallographic samples 30 are inserted into the sample holder 24 or sample receiving portion. The illustrated embodiment works with a central pressing force. Alternatively, it is also possible to work with a single pressing force, wherein the samples 30 are each pressed against the grinding plate with a respective pressing column and are clamped in the sample holder 24 in an axially non-fixed manner (not shown).

The sample holder 24 and the six embedded samples 30 inserted therein are rotated about the rotation axis AK of the pressing column 20 or the connecting column 26. The six embedded samples 30 thus perform a circular movement about the axis AK and define an outer overall circumference 31 here, which in the present example has an overall outer diameter D _ g of approximately 130mm (fig. 4).

For grinding the sample 30, the grinding disc 16 is now rotated about the grinding disc axis AS on the one hand, and the sample holder 24 is rotated about the axis AK of the pressing column 20 on the other hand, wherein the axis of rotation AK of the sample holder extends in a laterally parallel offset manner to the axis of rotation AS of the grinding disc (fig. 4, 5). In particular, the total circumference 31 is located outside the disc axis AS, which is advantageous in that the circumferential speed at the rotational axis AS of the disc itself is equal to zero.

In the exemplary device head 14 with a central contact pressure, a pressing mechanism is provided, for example, with a linear guide 78 (fig. 9, 10), which linear guide 78 presses the sample holder 24 containing the embedded sample 30 against the grinding disc 16 with a predetermined contact pressure force F during a counter or counter rotation of the grinding disc 16 and the sample holder 24, in order to carry out a grinding process of the bottom surface 30a of the sample by means of grinding by means of an abrasive layer consisting of abrasive grains or abrasive grains on the top surface 16b of the grinding disc.

Referring to fig. 3, a sample 30 is an embedded sample, which consists of the actual sample material 32 to be investigated, for example for later hardness test measurements or for histological analysis by means of a microscope, for example a metallic test object, and a cylindrical block of plastic embedding material, in which the sample material 32 is embedded. The sample material 32 is particularly embedded in a plastic block 34 for easier handling. In this example, the plastic block is composed of two

different plastics

34a, 34b to achieve cost optimization. As embedding material, for example, bakelite, epoxy resin, thermosetting plastic, thermoplastic plastic or acrylic resin is used for transparent encapsulation.

Referring to fig. 4, the abrasive disc 16 is divided into a peripheral annular region 42 and a central region 44 located in the peripheral annular region. The abrasive disc is only covered with abrasive in the peripheral annular region 44, in this example in the form of hexagonal abrasive particles. There is no abrasive 46 in the central interior region, so that an annular separation line 48 separates the peripheral, abrasive-covered annular region 42 from the central, abrasive-uncovered interior region 44. In other words, the abrasive layer 47 is annular, with a central inner region 44 being vacated. The distance between the axes of rotation AK and AS is now selected such that the total circumferential line 31 of the embedded sample 30 intersects the separation line 48 between the peripheral annular region 42 and the central inner region 44, i.e. the inner diameter D _ i of the annular abrasive layer 47. In other words, the embedded sample 30 moves inwardly beyond the outer peripheral annular region 42 covered with abrasive as the abrasive disc 16 and sample holder 24 rotate until it enters the inner region 44 uncovered with abrasive. This results in the abrasive disc 16 not having abrasive covered locations that are not traversed by the embedded sample 30, thereby ensuring even abrasive wear.

The same is true on the outer edge 16c of the grinding disc 16, since the radial offset between the axes AK and AS is chosen such that the sample 30 also moves outwards beyond the outer edge 16c of the grinding disc 16.

In this example, the abrasive disc 16 is covered with abrasive material 46 in a hexagonal pattern, although this is not required. Other overlay patterns are also possible. Both the covering pattern and the annular shape of the abrasive layer can be produced in one working step by means of screen printing. By means of a screen printing method, a binder with abrasive grains as powder is printed on the surface of the abrasive disc 16, in this example directly on a metal plate forming the rigid carrier disc 62, so that the abrasive grains are bonded on the abrasive disc 16 in such a way that they are locally embedded in the binder at the desired locations. However, the carrier disc 62 may also include a woven intermediate layer (not shown) to which the abrasive particles are bonded.

It can also be seen more precisely with reference to fig. 5 and 6 how the now internally located sample 30 is moved inwardly through the outer peripheral annular region 42 covered with abrasive material or through the parting line 48 into the inner region 44 of the grinding disc 16 which is not covered with abrasive material. By rotating the sample holder 24 in addition to the grinding disc 16, it is also ensured that all samples 30 are also ground flat on their circumference 30c, except for the moment when they just enter the circular abrasive gap inside the inner region 44 or the annular abrasive layer 47.

In other words, the abrasive disc 16 is not completely covered with abrasive 46 over its entire face, but is merely externally annular. Since the sample 30 always follows a minimum spacing from the axis AS of the grinding disc 16 during the double rotation in the grinding process, a minimum circumferential speed of the abrasive relative to the sample 30 is maintained in each rotational position. By moving the sample 30 to be ground inside out via the peripheral, abrasive-covered annular region 42, not only the abrasive 46 in the peripheral annular region 42, but also the bottom surface 30a of the sample 30, is ground flat, so that the grinding plate 16 no longer needs to be ground. This first saves the user the time to grind the sample. Of course, as an additional benefit, the cost for the abrasive 46 may also be reduced, as less abrasive 46 is needed for the abrasive disc 16.

If the inner region 44 is also covered with abrasive material, AS is typically given in the prior art, no material removal of the abrasive material takes place in the region around the rotational axis AS of the abrasive disc 16, which results in a non-planar wear characteristic of the abrasive disc. The grinding disc must therefore be ground from time to time in order to flatten the grinding disc again. Otherwise, a specific transition is produced in the radius r _ s of the grinding disc during uneven wear, at which radius r _ s the total circumference 31 ends internally, which results in the sample 30 tending to be rounded and uneven during grinding in the edge region 30 c. Fig. 11 illustrates this problem of the rounding 33, as it occurs in previous grinding devices or grinding disks.

Returning again to the embodiment of the invention shown in fig. 1-6, the peripheral annular region 42 where grinding is performed has an outer diameter D _ a and an inner diameter D _ i, where in this example the outer diameter D _ a =300mm and the inner diameter D _ i =50mm. These dimensions match those of the sample holder 24 shown in fig. 4, the sample holder 24 being in the form of a sample-receiving disc which grips six embedded samples 30 in an annular arrangement about an axis AK and which itself has a diameter of 140 mm. In the present example, the sample 30 has a diameter of 40mm, and the total outer diameter D _ g of the outer circumference 31 is about D _ g =130mm. Thus, in this example, the intersection or spill area 43 of the sample 30 in the passive inner region 44 is a few millimeters.

However, the principle of the annular design of the actively milled face region 42 of the milling disc 16 is not limited to sample holders 24 with multiple samples 30, but can also be used for milling a single sample 30. In this regard, referring to fig. 7-10, a laboratory disc grinding apparatus 10' is shown having an apparatus head 14 that services a plurality of grinding stations 15 each having its own grinding disc 16. In this example, the apparatus head 14 is movably fixed on the housing 12 along the direction 52 so as to be able to serve a plurality of grinding stations 15 alternately. In this case, each grinding disc 16 rotates in its own collection trough 18. In addition, the laboratory disc mill apparatus 10' also includes two separate polishing stations 54.

Referring to fig. 8, each grinding station 15 has a grinding-disc receiving disc 58, which may be configured, for example, as a stable metal disc. The abrasive disc receiving disc 58 is rotated about the axis AS by an abrasive disc drive 60. The grinding disc 16 is attached to the grinding disc receiving disc 58, for example, in a releasable manner, for example by means of a magnet holder, but other techniques for attachment can also be used therein.

The abrasive disc 16 in turn consists of a rigid carrier disc 62 and abrasive 46 in the form of abrasive particles of a specific grain size bonded to the carrier disc 62, which are embedded in a binder, thereby forming an abrasive layer 47. The abrasive particles are applied here in a plurality of layers to the carrier disc in order to form a self-sharpening grinding disc 16. For this purpose, the abrasive particles as powder are printed, for example by means of a screen printing method, with a synthetic resin adhesive onto the grinding disc 16, in this example directly onto the top surface 62b of the carrier disc 62. By particle size, this means that approximately 3 to 100 layers of abrasive particles may be bound in a binder on the carrier disc 62. The thickness of the abrasive layer 47 thus produced is about 0.2mm to 1mm depending on the abrasive disc 16. By means of a screen printing method, it is possible on the one hand to produce the desired grinding pattern, for example hexagonal as shown in fig. 2, but also to produce a division of the peripheral annular region 42 covered with abrasive and the inner region 44 not covered with abrasive. By dividing into a peripheral annular region 42 covered with abrasive material and an inner region 44 not covered with abrasive material, a step 64 is created between the peripheral annular region 42 covered with abrasive material and the inner region 44 not covered with abrasive material at the annular separation line 48, the height of which step corresponds to the thickness of the abrasive layer 47, i.e. for example about 0.2mm to 1mm. The step 64 leading downwardly from the peripheral annular region 42 into the inner region 44 ensures that even when the abrasive 46 in the peripheral annular region 42 is significantly worn, the sample 30 has sufficient axial spacing from the top surface 62b of the carrier disc 62, and in particular no undesirable upward step occurs from the peripheral annular region 42 to the inner region 44, as would be the case in a conventional abrasive disc where the abrasive in the central region of the abrasive disc is not worn by one or more samples. Thus, regular grinding for the leveling disc can be dispensed with. The carrier disc 62 is attached with its bottom surface 62a to the top surface 58b of the abrasive disc receiving disc 58.

In the example shown in fig. 7-10, the sample holder 24 is embodied as a sample clamp 72. The sample holder 72 has three holding arms 74, the holding arms 74 being capable of automatically holding a single sample to automatically grind the sample. By means of the plurality of nozzles 76, for example, water can be automatically sprayed as a coolant and/or for rinsing purposes, or diamond suspensions of different particle sizes onto the grinding disk 16.

With reference to fig. 9 and 10, the apparatus head 14 has a linear drive mechanism 78, by means of which the sample holder 24 and thus the sample or samples 30 bear against the abrasive disc 16 with a defined force F, wherein the pressing columns 20 rotate simultaneously.

It is obvious to the person skilled in the art that the embodiments described in the foregoing are to be understood as exemplary and that the invention is not limited to these embodiments, but that it can be varied in a number of ways without departing from the scope of protection of the claims. Furthermore, it is clear that the features mentioned define important parts of the invention individually, irrespective of whether they are disclosed in the description, the claims, the drawings or otherwise, even if they are described together with other features. All features disclosed in relation to the laboratory disc grinding apparatus, method, replacement grinding disc and application are of course also applicable to the respective different categories of subject matter disclosed, and features of one exemplary embodiment are also applicable to another exemplary embodiment disclosed. This applies in particular to the two embodiments of fig. 1 to 6 on the one hand and fig. 7 to 10 on the other hand.

Claims

1. Laboratory disc grinding device (10, 10') with a rotating grinding disc (16) for flat grinding, in particular the bottom surface (30 a) of an embedded sample (30), comprising:

a device housing (12) having a grinding disc receiving disc (58) and a drive motor (60), by means of which the grinding disc receiving disc (58) can be rotated,

having a carrier disc (62) and a grinding disc (16) which is bonded to a top surface (62 b) of the carrier disc (62) by means of an adhesive, wherein the carrier disc (62) of the grinding disc (16) has a top surface (62 b) and a bottom surface (62 a), and wherein the grinding disc (16) can be detachably fixed to a grinding disc receiving disc (58) with the bottom surface (62 a),

wherein the grinding disk (16) is divided into a peripheral annular first surface region (42) and a central second surface region (44) arranged within the peripheral annular first surface region (42), wherein the top surface (62 b) of the carrier disk (62) is covered with bonded abrasive material (46) only in the peripheral annular first surface region (42), so that a peripheral annular first surface region (42) to be ground and a passive central second surface region (44) are formed.

2. The laboratory disc grinding apparatus (10, 10') according to claim 1,

wherein the abrasive material (46) is formed by abrasive grains and, in a cross-section of the grinding disc (16), the abrasive grains (46) define a common, annular, grinding first surface of the grinding disc (16) in an annular, peripheral first surface region (42) of the grinding and the carrier disc (62) of the grinding disc (16) forms a central, non-grinding second surface of the grinding disc (16) in the passive, central second surface region (44), and wherein, in a new, unworn state of the grinding disc (16), the common, annular, grinding first surface of the grinding disc is higher than the central, non-grinding second surface of the grinding disc (16).

3. The laboratory disc grinding apparatus (10, 10') according to claim 2,

wherein the height difference between the common annular first surface being abraded and the central non-abraded second surface is in the range of 50 μm to 5mm.

4. The laboratory disc grinding apparatus (10, 10') according to any one of the preceding claims,

wherein the abrasive material (46) is formed by abrasive particles and in the peripheral annular first surface region (42) to be abraded, the abrasive particles are bonded in a plurality of layers, preferably in 3 to 100 layers, to the top surface of the carrier disk (62) by means of an adhesive.

5. The laboratory disc grinding apparatus (10, 10') according to claim 4,

wherein the abrasive layer is configured as a multilayer self-sharpening, such that the dulled abrasive particles fall off during the grinding process and new abrasive particles thus automatically emerge from the layer lying therebelow on the surface.

6. The laboratory disc grinding apparatus (10, 10') according to any one of the preceding claims,

wherein the abrasive material (46) is formed of abrasive particles and is printed in a predefined pattern with an adhesive in the first face area (42) of the grinding periphery.

7. Laboratory disc milling apparatus (10, 10') according to any one of the preceding claims,

wherein the grinding disc (16) is round and has an outer diameter of between 100mm and 500mm, preferably between 150mm and 400mm, preferably 300mm +/-50mm.

8. The laboratory disc grinding apparatus (10, 10') according to any one of the preceding claims,

wherein the annular first face zone (42) of the ground periphery has an inner diameter D _ i and an outer diameter D _ a, wherein half of the difference between the inner diameter D _ i and the outer diameter corresponds to the radial width B _ r of the annular first face zone (42) of the ground periphery and has a value between 240mm and 20mm, preferably between 180mm and 25mm, preferably 30mm +/-10mm or 125mm +/-50mm.

9. The laboratory disc grinding apparatus (10, 10') according to any one of the preceding claims,

wherein the peripheral annular first face zone (42) to be ground has an inner diameter D _ i and an outer diameter D _ a, wherein the inner diameter D _ i is between 20mm and 450mm, preferably between 30mm and 300mm, preferably 50mm +/-30mm or 250mm +/-50mm, and/or the outer diameter D _ a is between 100mm and 500mm, preferably between 150mm and 400mm, preferably in the range of 300mm +/-50mm.

10. Laboratory disc milling apparatus (10, 10') according to any one of the preceding claims,

wherein the carrier disc (62) comprises a plate, in particular a metal or plastic plate, and/or wherein the abrasive material (46) consists of diamond particles.

11. The laboratory disc grinding apparatus (10, 10') according to any one of the preceding claims,

wherein the grinding disc (16) can be detachably adhesively fixed on the grinding disc receiving disc (58) at the bottom surface.

12. The laboratory disc grinding apparatus (10, 10') according to any one of the preceding claims,

wherein the device housing (12) has a collecting trough (18) for cooling liquid and grinding particles, wherein the grinding disc receiving disc (58) rotates in the collecting trough (18).

13. Laboratory disc milling apparatus (10, 10') according to any one of the preceding claims,

wherein one or more samples (30) are inserted into a sample holder (24) and pressed against the abrasive disc (16), and

wherein, in addition to the rotation of the grinding disc (16), during a grinding process the sample holder (24) rotates together with the sample (30) or with the plurality of samples (30), and during the rotation of the grinding disc (16) and the sample holder (24) an edge region of the sample (30) or the plurality of samples (30) extends radially inside beyond the annular first face region (42) of the grinding periphery.

14. Laboratory disc milling apparatus (10, 10') according to any one of the preceding claims,

wherein the laboratory disk grinding device has a device head (14) with a pressing column (20) for fixing a sample holder (24), with which one or more samples (30) inserted into the sample holder (24) are pressed with a predetermined pressing force onto the grinding disk (16), and wherein the sample holder (24) is in particular rotatable in order to achieve a rotation of the sample holder (24) in addition to a rotation of the grinding disk (16) simultaneously during a grinding process, wherein the rotation axes (AS, AK) of the grinding disk (16) and the sample holder (24) extend offset in parallel.

15. Laboratory disc milling apparatus (10, 10') according to any one of the preceding claims,

wherein the peripheral annular first face region (42) to be ground has an inner diameter D _ i and an outer diameter D _ a, and wherein half of the difference between the inner diameter D _ i and the outer diameter D _ a defines a radial width B _ r of the peripheral annular first face region (42) to be ground, and

i) In the case of a single sample, the radial width B _ r of the annular first surface region (42) of the grinding periphery is selected such that the diameter of the sample (30) protrudes internally beyond the inner diameter D _ i, in particular permanently or temporarily due to a radial displacement of the sample rotating during the grinding process, or

ii) in the case of a sample holder (24) having a plurality of inserted samples (30), the entirety of these samples defines a total outer diameter D _ g on the basis of the rotation of the sample holder, and the radial width B _ r of the annular first face region (42) of the grinding periphery is selected such that the total outer diameter D _ g protrudes internally beyond the inner diameter D _ i, in particular permanently or temporarily due to the radial displacement of the rotating samples during the grinding process.

16. Method for the planar grinding, in particular the bottom surface of an embedded sample (30), by means of a rotating grinding disc (16), in particular by means of a laboratory disc grinding apparatus (10, 10') according to one of the preceding claims, wherein:

using a grinding disc (16) with a carrier disc (62) and an abrasive material (46) bonded by means of an adhesive to a top surface (62 b) of the carrier disc (62), and wherein the carrier disc (62) of the grinding disc (16) has a top surface (62 b) and a bottom surface (62 a), wherein the grinding disc (16) is significantly larger than a sample (30) to be flat ground,

wherein the grinding disk (16) is divided into a peripheral annular first surface region (42) and a central second surface region (44) arranged within the peripheral annular first surface region (42), wherein the top surface (62 b) of the carrier disk (62) is covered with abrasive material (46) only in the peripheral annular first surface region (42) in order to form a peripheral annular first surface region (42) to be ground and a passive central second surface region (44),

wherein one or more samples (30) are inserted into the sample holder (24) and pressed onto the grating disc (16), and

wherein, in addition to the rotation of the grinding disc, the sample holder (24) together with the sample (30) or samples (30) is rotated during the grinding process, and upon rotation during the grinding process, the edge region of the sample (30) or samples (30) is moved internally beyond the peripheral annular first surface region (42) to be ground and into a passive central second surface region (44).

17. Replacement grinding disc (16) consisting of a carrier disc (62) and abrasive grains bonded thereto by means of an adhesive, which is designed for use in a laboratory disc grinding apparatus (10, 10 ') according to any one of claims 1 to 15 for the flat grinding of a bottom surface (30 a) of a sample (30), in particular an embedded sample (30), wherein the grinding disc (16) is significantly larger than the sample (30) to be flat ground, wherein the carrier disc (62) of the grinding disc (16) has a top surface (62 b) and a bottom surface (62 a), and wherein the carrier disc (62) can be detachably attached with the bottom surface (62 a) to a grinding disc receiving disc (58) of the laboratory disc grinding apparatus (10, 10'), and

wherein the grinding disk (16) is divided into a peripheral annular first surface region (42) and a central second surface region (42) arranged within the peripheral annular first surface region (42), wherein the top surface (62 b) of the carrier disk (62) is covered only in the peripheral annular first surface region (42) with abrasive grains as abrasive material (46) in order to form a peripheral annular first surface region (42) to be ground and a passive central second surface region (44).

18. Use of a replacement abrasive disc (16) according to claim 17 in a laboratory disc grinding apparatus (10, 10') according to any one of claims 1-15.