Rolling mill and scraper for rolling mill

Abstract

According to one aspect of the invention, the invention relates to a scraper (10) for a rolling mill and to a rolling mill having such a scraper. The rolling mill comprises at least one pair of milling rollers (1) between which milling material can be reduced in size. The grinding rollers (1) are carried by a chassis (8), and means for engaging and disengaging the rollers can be present in a manner known per se in addition to drive means for the rotational movement of the grinding rollers. The scraper comprises a blade (11) with a scraping edge (21) which can be pressed against a surface of one of the grinding rollers. The scraper further comprises a base which is mounted or can be mounted on the chassis (8) and a tool holder (14) on which the tool is fastened. The tool holder can be preloaded against the surface of the grinding roller (1) by a spring force relative to the base and can then be pressed against the grinding roller by the spring force.

Description

Technical Field

[0001] The invention relates to a rolling mill and a scraper used for the rolling mill. Background Art

[0002] Rolling mills are used in grain mills or other mills for food processing. Rolling mills comprise at least one pair of grinding rollers, between which a grinding gap is formed during operation and which rotate, for example, at different speeds, in order to reduce the size of the milled material in the grinding gap. In this process, the grinding rollers are pressed against each other by a large pressing force, which is why a part of the milled material adheres to the grinding rollers after passing through the grinding gap. For this purpose, the rolling mill comprises a scraper, by means of which the milled material adhering to the grinding rollers is scraped off. Such a scraper usually comprises a blade, which is pressed against the respective grinding roller along a scraping edge by the pressing force.

[0003] The challenge associated with scrapers is that the grinding rollers are usually curved and the blades must be adapted to the shape of the grinding rollers. However, over time, the surface of the grinding rollers and the shape of the blades undergo changes due to wear.

[0004] According to the prior art, for this reason, a flexible blade made of spring steel is proposed, which is pressed against the surface of the grinding roller. This works satisfactorily in the case of the relatively short rollers used previously. Since the flexibility of the blade is usually not enough to bring about a sufficient adaptation over the entire grinding roller length in the case of longer rollers, other measures are proposed. CH 201 605 and GB 477 188 propose to introduce the blade into a slotted tubular element, wherein they are loosely supported movably so that they perform a certain tilting movement and can thus be pressed against the grinding roller. The required pressing force on the tubular element is applied by a connecting rod connected to the separation mechanism of the grinding roller, or alternatively, by a spring mechanism engaged between the arms of the tubular element. However, since the tool must be relatively long in the y direction (in the direction of the tool plane perpendicular to the direction of the scraping edge), the space required is relatively large. However, due to the inherent rigidity of the tool, this solution also has its limitations in the case of longer rollers.

[0005] An alternative approach consists in providing a rigid support for a plurality of mechanical tensioning elements distributed over the length of the scraper, by means of which the blade is bent, adapted to the roller surface and then pressed against the roller. This solution has the disadvantage that it requires a complex adaptation step, requires certain expertise and does not allow compensation in the event of deformation during operation.

[0006] Another possible solution according to EP 3 572 153 is an elastic soft support of the blade by an elastomer strip, which together with the blade can be held in the clamping profile. With regard to this solution, a disadvantage is that it is necessary to use an elastomer whose properties change over time. In addition, with regard to the solution proposed in EP 3 572 153, the pressing force of the blade must be applied by a counterweight, which makes the device heavy and complicates the assembly and replacement of the blade.

[0007] GB 1 015 565 describes a scraper having blades which comprise grooves at the rear side and which comprise cutouts from the scraping edge at the front side, between which cutouts the tongue of the scraper is formed. The cutouts form a non-right angle to the scraping edge, whereby, with increasing wear of the blade, the position of the corner at the scraping edge shifts, whereby the higher wear of the roller caused by the corner of the tongue compared to the wear caused by the remaining blades gradually affects the entire roller length. Summary of the invention

[0008] The object of the present invention is to provide a scraper for a rolling mill and a rolling mill having such a scraper, which overcomes the disadvantages of the prior art. In particular, the object of the present invention is to provide a compact scraper which enables good and uniform pressing of the scraping edge on the grinding roller.

[0009] According to a first aspect of the invention, the invention relates to a scraper for a rolling mill and a rolling mill having such a scraper. The rolling mill comprises at least one pair of grinding rollers, between which the grinding material can be reduced in size. The grinding rollers are carried by a chassis (e.g. with a support and / or a housing), wherein, in a manner known per se, in addition to a drive mechanism for the rotational movement of the grinding rollers, usually at different rotational speeds, there are also mechanisms for engaging and disengaging the grinding rollers. The scraper comprises a tool with a scraping edge, which can be pressed against the surface of one of the grinding rollers. In addition, the scraper comprises a base mounted or mountable on the chassis and a tool holder, to which the tool is fastened. The tool holder can be preloaded against the surface of the grinding roller by a spring force relative to the base and can then be pressed against the grinding roller by this spring force.

[0010] The tool support can be a tool holder in which the tool is clamped.

[0011] The base can be one-piece or multi-piece and, for example, fixedly assembled at the bottom frame of the rolling mill. In a simple case, the base can respectively include a base plate at the two axial ends of the scraper, relative to which the knife support is pivotably supported.

[0012] In the case of a multi-part design of the base, in an embodiment, the base can include at least one base-fixed part (e.g. the above-mentioned base plate) and at least one movable base part. The movable base part can be moved, for example, by a separation movement of the grinding rollers - or by an activation mechanism that causes this separation movement - in order to lift the scraping edge of the tool from the surface of the respective grinding roller as soon as the grinding rollers are separated relative to each other. In this case, the spring force can act between the movable base part, for example the base-pivoting unit, on the one hand, and the tool support on the other hand. Thus, the movement of the movable base part from the separation position into the engagement position can firstly cause the tool support with the tool fastened thereto to pivot to a certain extent, so that the scraping edge abuts against the grinding roller and then (further) preloads the spring, while the abutment of the scraping edge against the grinding roller prevents a further pivoting of the tool support.

[0013] For example, such a movable base part can be provided in particular for a tool which interacts with a fixed grinding roller in the center of the roller pair, while this can optionally be omitted on the side of the other grinding roller whose axis is displaced during the separating movement, in that during the separating movement the tool accompanies the grinding roller only as far as a mechanical stop which then causes the tool to be lifted from the grinding roller.

[0014] The prestressing by the spring force makes a counterweight superfluous. This allows a particularly compact design. Since the spring force acts between the tool support and the base, it is also well defined at all times. This is the case both when the spring is fixedly clamped relative to the base at the end opposite the tool support and when it is clamped in the movable base part. In the latter case, the scraper can be configured in particular such that the position and orientation of the movable base part is defined by the state of the paired grinding rollers and a distinction is made between the engaged state and the disengaged state.

[0015] The spring force acts between the tool support and the base and is therefore well defined at all times, in contrast to solutions according to the prior art in which the spring force acts between the two tools and the position of one tool influences the spring force on the other tool.

[0016] The spring force can be realized in particular by one or more springs on each tool support. Another advantage of the concept of having the spring force act between the tool support and the base is that the spring acting relative to the base can be placed in a contained manner, that is to say in a manner isolated from the grinding object. In particular, the spring can be present in a cavity inside the tool support and / or the base. Such a cavity can, for example, extend along the pivot axis of the tool support. The cavity can also be used to guide the tool support, for example, by a guide pin of the base that engages with it. One end of the spring can also be fastened to such a guide pin, while the other end is in engagement with the engagement structure of the tool support. In an embodiment with a movable base part, the guide pin can participate in the pivoting movement of this movable base part so as to (further) preload the spring in the above-mentioned manner.

[0017] The spring that is not arranged in the product space especially has the advantage of sanitation.In addition, under the situation of defect (for example the fracture of spring), the component of spring can not enter in the product flow.

[0018] It is particularly advantageous from a production point of view if the tool holder is formed as a profile body extending in the axial direction and optionally has a cavity and an engagement structure into which the end of a spring optionally arranged in an opening can engage in order to apply a spring force.

[0019] In particular, the scraper can comprise a scraping unit with a tool and a tool holder for each of the two grinding rollers of the roller pair. The two tools can be preloaded against the surface in each case relative to a base. Here, the tool holders of the two tools can share a base, that is, be fastened to the same base and be preloaded or preloadable relative to it, which, as mentioned above, does not exclude a multi-piece solution for the base. With this solution, the scraper with two scraping devices can then be present as a component (module). Such a component can be preassembled and only needs to be fastened to the base frame, that is, the assembly and disassembly of the scraper is significantly improved compared to the prior art. The compact design also has advantages in terms of hygiene and ease of sampling under the rollers.

[0020] In an embodiment, the tool comprises a plurality of (first) grooves. These grooves are arranged between the tool support (e.g., tool holder) and the scraping edge, which does not exclude that they can extend into the area received by the tool support. These first grooves cause that, even in the case of a sufficiently high strength of the tool material, the tool is flexible enough to fit evenly to the roller surface even in the absence of an elastic support. Good fit means that the tool can locally apply as uniform a pressing force as possible in different axial positions and thus has the same scraping function and the same wear locally.

[0021] The first grooves are arranged in particular at a distance from the scraping edge, ie they do not extend to the scraping edge. The first grooves, whatever their shape, are usually window-like, ie can be surrounded by the material of the tool along their entire circumference.

[0022] In one embodiment, the scraping edge is uninterrupted in particular along its axial extension. This has the advantage that scraping is carried out uniformly along the entire axial extension of the grinding roller without residual marks. Since the first groove is then located between two areas that are uninterrupted along their axial extension, the tool as a whole is torsionally rigid despite the increased flexibility of the tool achieved by the groove.

[0023] However, in addition to or instead of the first groove, the tool can also have a targeted weakening of a different shape, which allows a good fit. This can be a cutout and / or a partition in particular. Such a cutout or partition can extend downward from the scraping edge (in the y direction, that is, in the direction of the tool plane perpendicular to the direction of the scraping edge). The cutout or partition makes the tool more flexible during torsion and causes the tool to fit in sections to the surface of the grinding roller.

[0024] In the embodiment with the first recess, cutout and / or division, the tool holder is designed in a particularly dimensionally stable (rigid) manner, for example in that it is formed from one or more metal bodies. The tool is particularly supported directly by the tool holder without elastic intermediate elements or the like, so that the position of the area of ​​the tool received by the tool holder is defined over the entire axial extension. The fit properties are therefore defined by the blade itself.

[0025] The problem of adapting to the roller surface described at the outset is thus solved in an easy manner. Due to the first groove, the cutout and / or the dividing portion, the tool can be bent relatively flexibly, so that the scraping edge can well follow the curved surface of the roller, for example. However, the necessary rigidity in the direction of the plane of the tool, in particular in the y-direction, is not impaired, that is, the scraping function of the tool is ensured independently of the first groove. The disadvantage of a tool that is too thin or too long (in the y-direction) is also avoided.

[0026] According to the concept of providing the tool with the first groove, cutout and / or partition, the flexibility of the tool and its ultimate ability to adapt to the roller surface and transmit the pressing force is determined by the rigidity of the tool. This proves to be particularly advantageous. Firstly, due to the size and shape of the first groove, cutout and / or partition, the bending rigidity of the tool in the area below the scraping edge can be set practically arbitrarily, if necessary also over the axial length of the tool, and more precisely without the need to adapt the tool holder. Secondly, there is no need to use elastic materials or other plastic materials whose properties change over time.

[0027] In an embodiment with first grooves, these grooves are distributed along the axial extension of the tool, for example in a regular arrangement, for example in a (single) row. Between the first grooves, a web can be formed, which connects the axially continuous scraping edge area with the likewise axially continuous intermediate area. The width of the web at its narrowest point is selected according to the required flexibility. This width can be smaller than the width of the groove, in particular at most 1 / 2, at most 1 / 3 or at most 1 / 5.

[0028] The first groove can be rectangular in particular. This has the advantage that the web extends in the y direction (here the y direction is the direction along the tool surface towards the tool edge or away from the scraping edge) and can have an approximately constant width over its length between the grooves. Thus, in the event of a curvature of the blade (for adapting to the roller surface), the curvature is uniform in the region of the web. However, it is not excluded that the first groove has other shapes, for example an ellipse, a circle or a hexagon, etc.

[0029] The concept of a tool with a first recess of the type discussed herein between the scraping edge and the tool holder, with cutouts and / or divisions, is particularly advantageous in conjunction with a tool holder that (especially without a counterweight) is pressed against the roller due to spring force, that is, in a scraper and a rolling mill according to the first aspect. However, according to a further second aspect of the invention, the concept can also be used in rolling mills without such a pressing mechanism, that is, in particular in general in rolling mills with a pair of grinding rollers and a tool with a scraping edge that can be pressed against the surface of one of the grinding rollers. The advantage of a uniform fit to the surface of the roller is achieved independently of the way in which the pressing force is generated.

[0030] According to a third aspect of the invention, the following problem is addressed: The knives of a scraper of the type described here have a limited service life because they wear out over time. This service life is usually about one to three years, depending on the intensity of use. If the scraper knife is worn out, it no longer sufficiently separates the grinding roller from the adhering product. More precisely, a surrounding product strip is formed on the surface of the grinding roller. This has the result that the machine no longer grinds in the correct manner and that increased vibrations occur. Usually, the operator only recognizes that the knife is now worn out and needs to be replaced based on this insufficient result. Therefore, it is desirable to have a mechanism by which the operator is aware in good time that the knife will soon wear out.

[0031] The third aspect can be implemented independently. It can also be combined with the first aspect and / or the second aspect in an advantageous manner. With regard to the third aspect, it is also applicable to a scraper of a rolling mill having a pair of grinding rollers and such a rolling mill having a pair of grinding rollers and a scraper, the tool of which is pressed against one of the grinding rollers (or the two tools are pressed against one of the grinding rollers respectively). The scraper also includes a tool with a scraping edge, which can be pressed against the surface of one of the grinding rollers. Over time, due to wear, the scraping edge moves "downward", that is, in the direction of the rear side, while on the front side at the scraping edge, some material of the tool is continuously worn away. According to the third aspect, the tool includes at least one cutout, for example a plurality of marking grooves, which are arranged so that when the tool reaches the service life, it is at the scraping edge. Here, the marking groove has a small width (extension in the x direction, that is, in a direction parallel to the scraping edge), for example, less than 5 mm, in particular at most 3 mm, at least at its front end. In this way, as soon as the material at the front side of the marking groove has been ground off, fine traces of the ground product that have not yet been scraped off appear on the roller. These traces are visible to the user and signal that the tool must be replaced soon. Nevertheless, the tool can still be used for a certain period of time without any problems and without generating increased vibrations, for example, until the time of replacement is advantageous.

[0032] The marking groove can in particular change gradually toward the front side, so that the trace that appears is first very narrow and then widens. The marking groove can, for example, have the shape of a small triangle with a tip pointing toward the front side.

[0033] The following applies to all aspects of the present invention:

[0034] The support of the tool in the tool holder can be brought about in particular in that a plurality of abutment parts of the tool holder abut against the tool and the tool holder acts as a tool holder. For example, a first abutment part, a second abutment part and a third abutment part can be present and they are offset from one another, wherein the first abutment part and the third abutment part abut against one side of the tool and the second abutment part abuts against the opposite side of the tool. Here, the second abutment part is located between the first abutment part and the third abutment part in the y direction. Clamping can then be brought about based on the elasticity of the tool, so that the tool can be clamped and additional fixing, for example by screws or the like, becomes superfluous.

[0035] However, it is not excluded that the tool is clamped between two blocks or the like of the tool holder, wherein additional means can then be provided in order to press the blocks against each other and / or to fix the tool.

[0036] With regard to the solution with mutually offset abutment sections, it is applicable that the abutment sections extend in the axial direction over the entire extension (width) of the tool. The abutment sections can form an uninterrupted abutment line. However, it is also possible that one of the abutment sections is present in the region of the (first) groove, that is, the abutment section abuts at the web between the grooves.

[0037] As a further possibility, the tool (independently of the presence or absence of a first groove, cutout, dividing portion and / or marking groove) can form a second groove which can interrupt the abutment line defined by the first, second and / or third abutment portion (or between them). The second groove is arranged in the area received by the tool holder (clamping area) and thus increases the flexibility of this area, which is why the above-mentioned clamping effect can be further improved by a slightly greater bending of the tool in the clamping area.

[0038] According to one embodiment, a second groove can be arranged at the tool at the bottom side and can optionally be open downwards so that the tool forms the applied projections of the bottom side. The lowermost (first) abutment portion can be present in the region of these projections of the bottom side. With this design, the tool also becomes slightly more flexible in the region of the first abutment portion.

[0039] The tool can then comprise, in particular, starting from the scraping edge, firstly an axially continuous scraping edge region, a region with the first recess, an axially continuous middle region and a lower region with the downwardly protruding projection.

[0040] By means of the design with the offset contact parts, the tool holder as a tool holder can in particular contain no connecting elements (screws etc.) in the product space. This is particularly advantageous in terms of hygiene and also in terms of easy replaceability of the tool.

[0041] In addition to the scraper, the invention also relates to a rolling mill having a scraper. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Embodiments of the present invention are described below by means of the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or similar elements. The accompanying drawings are partially schematic and not to scale. These drawings show elements that partially correspond to each other in different sizes in each figure. Among them:

[0043] Figure 1 Schematically showing an area of ​​a rolling mill with a scraper;

[0044] Figure 2 An area of ​​the scraper is shown in perspective;

[0045] Figure 3 An area of ​​one of the cutters is shown;

[0046] Figure 4 Shown from Figure 2 A cross-sectional view of a tool holder of a scraper;

[0047] Figure 5 Shown from Figure 2 A scraper having elements shown in dashed lines present within the interior of the tool holder;

[0048] Figure 6 From the end side shows the Figure 2 A view of the scraper;

[0049] Figure 7 An area showing an alternative tool;

[0050] Figure 8 An area of ​​a multi-piece tool is shown;

[0051] Fig. 9 A side view of a portion of an alternative scraper is shown with one of the grinding rollers of the pair separated;

[0052] Fig.10 Shown with Fig. 9 A similar view wherein the grinding rollers are engaged; and

[0053] Fig.11 An area of ​​the tool having a marking groove is shown. DETAILED DESCRIPTION

[0054] Figure 1 A pair of grinding rollers is shown, between which a grinding gap 2 is formed. The scraper 10 is designed as a unit with two scraping devices mounted on a base with a base plate 13, each having a tool 11 and a tool holder in the form of a tool holder 14. The tool 11 presses against the rotating grinding roller in the direction of the arrow in order to scrape off the grinding material adhering to the respective roller surface. In this case, in a manner known per se, the tool is arranged at an angle to the normal to the roller surface, that is, at an angle to a radial plane through the contact line.

[0055] The base is fixedly mounted relative to the axis of rotation of the grinding roller. Figure 1 Schematically indicated in FIG is a base frame 8 of a rolling mill, to which a base plate 13 is fastened. A "base frame" can include a machine frame and / or a load-bearing housing or other components that are immovably assembled.

[0056] Figure 2 A region of the scraper 10 is shown in a perspective view. It can be seen that the blade 11 comprises a row of grooves 22 below the scraping edge 21, between which narrow webs 23 are formed.

[0057] As already mentioned, the base comprises a base plate 13 at the end side; Figure 2 The base can include an additional base plate or other structure that pivotably receives the tool holder 14 (not visible in the figure).

[0058] The two tool holders 14 are each designed as a profile extending along an axis. An end plate 31 is provided on the end side of the tool holder 14 and is connected to the tool holder in a rotationally fixed manner.

[0059] exist Figure 3 In FIG. 1 , a region of one of the knives 11 can be seen. In addition to the grooves 22 with the webs 23 located therebetween, the knife also comprises second grooves 24 on the bottom side, open at the bottom, between which projections 25 applied on the bottom side are present.

[0060] Figure 3 The coordinates of the Cartesian coordinate system are also shown. In this context, the axis parallel to the tool surface of the scraping edge 21 and the axis of the grinding roller is denoted as the x-axis, and the corresponding direction is also denoted as the "axial direction". The directions perpendicular to this axial direction, along the tool surface "towards the roller surface" and "away from the roller surface", correspond to the y-direction or -y-direction; according to Figure 1 The arrangements shown are also indicated as "upward" or "downward". The y axes of the two tools are usually not parallel to each other, that is, the coordinate system is to be understood in relation to the respective tool.

[0061] Figure 4 A cross-sectional view through a tool holder with a clamped tool 11 in a tool holder 14 is shown. The tool is clamped by the tool resting on three axially extending resting portions 32, 33, 34 offset from one another and being clamped in this way. The tool holder 14 consists, for example, of a relatively hard and dimensionally stable material (for example aluminum). The resting portions can act in a clamping manner in that they cause a minimal bending of the tool 11 (which is relatively elastic due to the thickness of the tool and / or due to the composition of the tool material), which is why the tool is clamped elastically in the tool holder 14. The prestressing of the tool thus ensures the fixation of the tool in the tool holder.

[0062] In this respect, the second groove 24 on the lower side serves to increase the elasticity of the region of the first contact portion 32 somewhat, in that essentially there is an applied projection 25 which bends slightly during clamping. Figure 3 The dotted lines in FIG. 1 indicate the region where the first abutting portion, the second abutting portion and the third abutting portion 32 , 33 , 34 abut.

[0063] The necessary squeezing force is achieved by the spring. Figure 5It is particularly evident that the base comprises a pin 41 which is fixedly mounted on the base plate 13 in a rotationally fixed manner and which can also be formed in one piece with the base plate. The pin 41 fits precisely into a cylindrical, axially extending guide opening (42; Figure 1 In the interior of the tool holder 14 (schematically shown in FIG. 1 ), the guide opening is coaxial with the pivot axis of the tool holder 14 and defines the pivot axis.

[0064] A fixing slot 43 is provided on the pin 41, into which the crank-shaped end 45 of the torsion spring 44 projects. A second crank 46 provided near the other end engages with a groove-shaped radial projection 47 of the guide opening, whereby the (prestressed) torsion spring 44 presses the tool holder 14 in the direction of the grinding roller 1, as shown in FIG. Figure 1 Other types of springs and corresponding mechanisms are also conceivable (by which the tool holder 14 is pressed in a defined rotational direction based on the spring action of one or more springs supported at the base), such as a helical spring that engages at the fixing slot 43 of the pin on one side and at the radial projection on the other side, or a tension spring or compression spring that engages externally at the base and at the junction of the tool holder, etc.

[0065] exist Figure 6 The end plates 31 fastened to the respective tool holder 14 by means of screws each comprise a reset arm 51. For example, a mechanism can be engaged at the reset arm, which deflects the tool holder against a spring force so that the tool no longer contacts the grinding rollers as soon as the grinding rollers separate, that is to say move away from each other. This prevents the tool from rubbing against the grinding rollers when no product is being ground between the grinding rollers as they rotate.

[0066] The substrate 13 is Figure 6 The groove 52 which can be seen particularly well in FIG. 1 is used for assembling the preassembled unit of the scraper on the base frame of the rolling mill.

[0067] Figure 7 An alternative tool 11 is shown which has no grooves but has a cutout 61. The tool is interrupted in the y direction up to the scraping edge 21 by the cutout 61. This results in a row of tongues 62 which extend from the axially continuous region up to the scraping edge 61 and can be individually attached to the roller surface. In the example shown, the tool (with Figure 2-Figure 6 Like the tool shown, the tool 20 comprises second grooves 24 on the bottom side that are open at the bottom and between which projections 25 applied on the bottom side are located.

[0068] exist Figure 8In the embodiment with a dividing section, the cut is replaced by a dividing section 71 which is continuous in the y direction, whereby the tool is multi-part and divided into a plurality of adjacently arranged sub-tools 72. These sub-tools are arranged directly adjacent to each other and can all have the same width (extension in the x direction), or the width can be adapted as required, for example, the width in the edge region is smaller or larger than in the middle region. In the embodiment with a dividing section, a (second) groove on the bottom side is also an option, wherein the number of raised sections applied on the bottom side can then be the same for all sub-tools, for example, that is, the positions of the raised sections and the dividing section can be matched to each other.

[0069] Fig. 9 and Fig.10 The principle of a multi-part design of the base is shown in order to provide a movable base part for a tool holder of at least one of the tools, wherein the tool holder is preloaded relative to the movable base part by a spring and pivots during an engaging and disengaging movement.

[0070] exist Fig. 9 8. In the disengaged state, the base is shown in FIG. 1. In addition to the base plate 13, the base also comprises a movable base part in the form of a base-pivoting unit, namely a pivot plate 81. During the engagement and disengagement movement, the pivot plate is pivoted by the disengagement mechanism of the roller pair, for example in that a follower (not shown) of the disengagement mechanism interacts with the pivot plate arm 82. The pin 41, which interacts with the end of the torsion spring similarly to the previous embodiment, is supported relative to the pivot plate 81 and participates in the pivoting movement of the pivot plate.

[0071] Furthermore, in the example shown, the pivot plate 81 forms a stop 85 which, in the separated state ( Fig. 9 ), an element of the tool support - in the example shown, a stop plate 83 fixedly screwed to the tool holder - is located at this stop due to the spring force of the torsion spring, whereby the tool 11 is in a specified position in which the scraping edge is not located on the grinding roller 1.

[0072] If the pivot plate 81 is pivoted to the engaged state ( Fig.10 ), then on the one hand the stop 85 moves so that the tool and the tool holder 14 are no longer prevented from pivoting toward the grinding roller (see Fig.10 On the other hand, by pivoting the pin 41, the end of the torsion spring connected thereto is also pivoted, which additionally tensions the torsion spring and causes the tool to be pressed (more vigorously) against the surface of the grinding roller 1.

[0073] In a variant, the stop 85 can also be omitted, or alternatively the provision of the pin 41 on the movable base part can be omitted. In the latter case, however, the torsion spring will be more intensely tensioned during separation, so that part of the separation movement will be performed by overcoming the spring force of the torsion spring. Fig. 9 and Fig.10 The embodiment in prevents this. If the separation movement - as described, for example, in patent application CH 000 148 / 2023 - is caused by a spring, this spring must be particularly strong, which in turn has the consequence that more energy must be consumed for the engagement movement, as the separation movement is to act against the spring force of the torsion spring and is to always ensure a defined state. Fig. 9 and Fig.10 Solutions that prevent this then contribute to reliability and energy efficiency.

[0074] Fig.11 A tool 11 is shown having a window-shaped recess 22 of the type described above and additionally having a marking recess 91. The marking recess 91 is arranged at a distance a from the scraping edge 21. This distance a is selected so that the tool 11 always fulfills its function when all material between the (original) cutting edge 21 and the marking recess 91 has been worn away, that is, when the cutting edge 21 is displaced relative to the marking recess 91 due to wear. However, it is no longer tolerable that material is worn to the rear side ( Fig.11 Once the position of the cutting edge moves toward the marking groove 91, fine marking stripes appear on the surface of the grinding roller due to the marking groove. These marking stripes indicate to the operator that the tool 11 should be replaced.

[0075] Due to the optional triangular shape of the marking recess 91 which tapers toward the front, the marking stripe becomes wider and wider if the knife 11 is used further, ie the marking becomes more and more obvious with increasing urgency.

Claims

1. A scraper for a rolling mill, the rolling mill comprising a chassis carrying a pair of grinding rollers (1) between which the grinding material can be reduced in size, wherein: The scraper comprises: a tool (11) having a scraping edge (21) which can be pressed against the surface of one of the grinding rollers (1); and a tool holder (14) to which the tool (1) is fastened, characterized in that it has a base which can be assembled on the base, wherein the tool holder (14) can be preloaded against the surface of the grinding roller (1) by a spring force relative to the base and can then be pressed against the grinding roller by this spring force.

2. The scraper according to claim 1, wherein: The scraper comprises, for each of the two grinding rollers (1) of the pair of grinding rollers (1), a scraping unit having a knife (1) and a knife support (14), which can be preloaded against the surface of the grinding roller (1) by a spring force relative to the base and can thus be pressed against the grinding roller by this spring force.

3. The scraper according to claim 2, wherein: The blade supports (14) of the two scraping units are mounted on the base as a common base, whereby the scrapers can be fastened as an assembly on the chassis.

4. The scraper according to any one of claims 1 to 3, comprising at least one spring (44) for applying the spring force.

5. The scraper according to claim 4, wherein: The spring is present in a cavity of the base and / or of the tool holder.

6. The scraper according to any one of claims 4 or 5, wherein: The spring acts between a movable base part of the base on the one hand and the tool support on the other hand, and the movable base part of the base can be moved between an engaged state and a disengaged state by moving one grinding roller (1) of the pair of grinding rollers relative to the other grinding roller (1) so as to preload the spring in the engaged state.

7. The scraper according to any one of claims 4 to 6, wherein: The spring is a torsion spring.

8. A scraper according to any one of the preceding claims, wherein: The tool (11) or at least one of the tools (11) comprises a plurality of first grooves (22), wherein the first grooves are present between the tool support (4) and the scraping edge (21).

9. A scraper according to any one of the preceding claims, wherein: The tool (11) or at least one of the tools (11) comprises a plurality of cutouts (61) and / or dividing portions (71) extending to the scraping edge (21).

10. A scraper according to any one of the preceding claims, wherein: The tool support (14) is a tool holder in which the tool (11) is clamped during deformation.

11. The scraper according to claim 10, wherein: The tool holder comprises three mutually offset abutment parts (32, 33, 34), wherein one abutment part is arranged opposite to the other two abutment parts.

12. The scraper according to claim 10 or 11, wherein: The tool (11) comprises a plurality of second recesses (24) which are arranged in a region received by the tool holder.

13. A scraper according to any one of the preceding claims, wherein: The tool comprises at least one marking groove which is arranged at a distance from the scraping edge (21) and which has, at least at its front end, an extension of at most 5 mm in a direction parallel to the scraping edge.

14. A rolling mill, comprising: a chassis carrying a pair of grinding rollers (1) between which the grinding material can be reduced in size; And a scraper (10) according to any of the preceding claims, wherein the base is fastened to the chassis and the scraper is arranged such that a scraping edge (21) of the knife (11) is pressed against one of the grinding rollers by spring force.

15. A scraper, for example a scraper according to any one of claims 1 to 13, for a rolling mill having a pair of grinding rollers (1) between which the grinding material can be reduced in size, wherein: The scraper comprises: a tool (11) having a scraping edge (21) which can be pressed against the surface of one of the grinding rollers (1); and a tool holder (14) to which the tool (1) is fastened, characterized in that the tool (11) comprises a plurality of window-shaped first grooves (22) and / or cutouts (61) and / or dividing portions (71).

16. The scraper according to claim 15, wherein The first groove (22) exists between the tool support (4) and the scraping edge (21), and the scraping edge (21) extends in an uninterrupted manner along its axial extension.

17. The scraper according to claim 15, wherein: The cutout (61) or dividing portion (71) extends as far as the scraping edge (21).

18. The scraper according to any one of claims 15 to 17, wherein: The first grooves (22) are arranged in an array extending in the axial direction.

19. The scraper according to any one of claims 15 to 18, wherein: The first groove (22) is rectangular.

20. The scraper according to any one of claims 15 to 19, wherein: The width of the web (23) between the first grooves (22) is at most 1 / 2 of the width of the first groove (22).

21. A rolling mill, comprising: a pair of grinding rollers (1) between which the grinding material can be reduced in size; And a scraper (10) according to any one of claims 15 to 20, wherein the scraper is arranged so that the scraping edge (21) of the knife (11) is pressed against one of the grinding rollers.

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