Roller set and roller mill

Abstract

One aspect of the invention relates to a grain mill, namely a roller mill. The roller mill has at least one roller set, comprising a first milling roller, which is supported on both sides by a respective first bearing body, and a second milling roller, which is supported on both sides by a respective second bearing body. The second bearing bodies can be moved relative to the first bearing bodies by a respective electric drive. The roller set is designed to move the second milling roller relative to the first milling roller by moving the second bearing body in order to set the width of the milling gap which is produced between the first and second milling roller. According to one aspect of the invention, the roller set has an electronically readable physical operating element (202) which produces a movement of at least one of the electric drives on the basis of a movement of the physical operating element.

Description

[0001] ROLLER PACK AND ROLLER HALL

[0002] The invention relates to a roller mill for processing cereal products.

[0003] Roller mills are used in grain mills for food processing. A roller mill consists of at least one set—often two or four sets—of two grinding rollers each, between which a grinding gap is formed during operation. These rollers rotate—generally at different speeds—to crush the material in the grinding gap.

[0004] Common roller assemblies have a fixed and a movable bearing body on either side of the grinding rollers. The movable bearing body can be moved between an engaged and a disengaged position relative to the fixed bearing body for coarse gap adjustment by a generally pneumatically operated disengaging device. Common roller assemblies also feature an adjusting device for fine adjustment, which can be operated manually, mechanically, or by means of an electric motor.

[0005] Fine adjustment with the aid of an electric motor enables programming – for example, the width of the grinding gap can, at least theoretically, be set to a stored value, e.g., according to a specific recipe. However, conventional roller mills do not have the option of specifying the grinding gap in a unit of length (e.g., micrometers). Thus, at most, a reference value is assigned to the current grinding gap, based on which this gap can be readjusted later. However, this reference value is not suitable as a process-related parameter. Therefore, specialists operating a roller mill with mechanical grinding gap adjustment rely on their experience and instinct when adjusting the grinding gap or perform relatively complex granulation measurements of the material to be ground.

[0006] An electronically adjusted grinding gap offers only minimal advantages over a manually-mechanically adjusted gap, since the former can only be adjusted remotely with a residual risk. The operator must be certain that the grinding gap is appropriate for the process and machine. However, apart from a reference value, they have no indication of how large the grinding gap actually is. Thus, they are missing an important assessment parameter. Another disadvantage is the fact that mechanical tolerances can change over time, which is why a grinding gap that has been precisely adjusted electronically can also become misaligned over time – which, due to the lack of haptic feedback, can only be noticed indirectly by specialists, for example, based on the result of the grinding process.

[0007] In particular, after roller changes or other maintenance work, the entire adjustment process must be restarted. Furthermore, the grinding gap can only be adjusted to a narrower gap by actuating the mechanical control element against a counterforce. If, however, the grinding gap is to be made wider, the rollers must first be moved further apart and then the width of the grinding gap reduced again to the desired setting. DE 27 30 166 shows, among other things, a schematically illustrated, control-controlled adjustment device for the distance between the bearing bodies of the two grinding rollers. A target value for the gap width can be corrected by a manual input that is not described in detail. The problems of the prior art described at the beginning are neither addressed nor solved in DE 27 30 166.

[0008] It is therefore an object of the present invention to provide a roller mill for grinding cereal products which overcomes disadvantages of the prior art and which offers advantages in terms of user-friendly adjustability and reproducibility.

[0009] This problem is solved by a roller package and a roller mill as defined in the patent claims.

[0010] According to one aspect of the invention, a grain milling machine, specifically a roller mill, is provided. The roller mill has at least one roller assembly, with a first grinding roller, which is supported on each side by a first bearing body, and a second grinding roller, which is supported on each side by a second bearing body. The second bearing bodies are each movable relative to the first bearing bodies by an electric drive. The roller assembly is configured to move the second grinding roller relative to the first grinding roller by moving the second bearing body in order to adjust the width of a grinding gap that results between the first and second grinding rollers.According to one aspect of the present invention, the roller mill has an electronically readable physical operating element, wherein the roller mill is configured to cause a movement of at least one of the electric drives depending on a movement of the physical operating element. In contrast to, for example, a touch-sensitive screen or a membrane keypad, a physical operating element is an element that is physically movable relative to a housing, for example a handwheel (which can be designed as a rotary / push wheel with a triggering movement in the axial direction with respect to the rotation axis), or a sliding lever, etc. The physical operating element can in particular - in contrast to, for example,to buttons or keys - be movable in mutually opposite, defined directions of movement, whereby the path traveled in one of the directions of movement determines the distance by which the electric drive moves the second bearing body relative to the first bearing body in a direction of movement defined by the direction of movement of the control element. For a handwheel, the two directions of movement are clockwise and counterclockwise rotation, while for a sliding lever, these are the two opposite sliding directions.

[0011] The movement caused by the electric drive can, in particular, be proportional to the movement of the physical control element. This also means that, for example, with a handwheel as the physical control element, a full revolution always defines a defined distance of movement, at least in a given operating mode, regardless of the current position. In embodiments, one revolution of the handwheel can, for example, correspond to a difference in the grinding gap (in parallel operation; in single-sided operation, to the width of the grinding gap at the corresponding axial end of the grinding rollers) of between 0.05 mm and 0.2 mm, in particular between 0.08 mm and 1.5 mm, for example approximately 0.1 mm.

[0012] Firstly, the procedure according to the invention improves reproducibility compared to the prior art in that the physical control element determines the position of the second bearing body relative to the first bearing body in a reproducible manner via the electric drive. Secondly, the physical control element enables physical feedback, which can give the operator a direct feeling for the effect of the movement of the physical control element. Nevertheless, positions once deemed satisfactory can be stored electronically and easily recalled later. Thirdly, further disadvantages of mechanical adjustment are overcome. In particular, with the procedure according to the invention, in contrast to the prior art, the position indicator (generally in the form of a handwheel clock in the prior art) cannot break apart.With mechanical handwheel clocks, depending on the design, there is also the problem that the handwheel lock clamps too tightly (seizure) or too loosely (gap gets adjusted).

[0013] Another advantage compared to a mechanical handwheel is that no penetration through the machine cover is necessary (no sealing points) and there is no risk of collision, for example when changing rollers.

[0014] The handwheel, in particular, has the advantage that it does not have a predetermined end position, allowing purely electronic calibration, regardless of the diameter of the grinding rollers. A further advantage of a handwheel is that it corresponds to the control element familiar to experts from roller mills with mechanical adjustment of the grinding gap. Existing experience can therefore also be applied to the use of roller packages and roller mills according to the present invention.

[0015] The physical control element is electronically readable by being configured to electronically record its position and / or movement, which can be used for electronic evaluation, for example, by outputting the position or movement as a digital signal. An example of an electronically readable physical control element is a so-called electronic handwheel, i.e., a handwheel combined with an electronic rotary movement and / or rotary position detection device. Electronic handwheels are well-known and commercially available, for example, for CNC machine tools.

[0016] The roller mill can, in particular, have a control unit that reads the physical control element or receives the readout signal and converts the movement of the physical control element into a movement of both electric drives in parallel operation by supplying them—which can, for example, comprise servo motors—with appropriate control signals. This means that the roller mill can be configured (configured and / or programmed) to enable manual adjustment of the grinding gap width in parallel operation.

[0017] Such a control unit can be a dedicated roller stack control unit, or it can be fully or partially integrated into a control module of the entire roller mill and / or partially integrated into at least one external component—e.g., a universal computer connected via an interface, a mobile device, and / or a higher-level controller for controlling multiple devices of a grain mill. It can also, if necessary, be formed at least partially by the integrated electronics unit of the electronic handwheel (or similar).

[0018] The physical operating element, e.g. handwheel, can in particular be configured to generate physical feedback during operation which depends on the status of the grinding rollers. Physical feedback is feedback that the user feels on the operating element itself, in particular so-called force feedback, sometimes also referred to as 'haptic feedback'. The physical feedback can in particular require that - in particular by a control unit - status information about the grinding rollers is evaluated and the physical operating element applies the physical feedback depending on this status information - i.e. depending on the results of the evaluation. As mentioned, the status information is information about a state - e.g. a position - of the grinding rollers and is therefore different from a mere state of the operating element.In other words, even if the physical control element is electronically readable and therefore mechanically decoupled, for example, from the elements that can move the grinding rollers relative to each other, information about this status can still be transmitted to the user via the control element. Information therefore flows in both directions: from the user via the physical control element to the drive that moves the grinding rollers (namely, via the electronic readout of the control element), on the one hand, and from the roller mill (its control unit, for example) via the physical control element to the user – namely, via physical feedback.

[0019] For example, the physical feedback can depend in particular on the current position of the bearing bodies, i.e., the current width of the grinding gap. Additionally or alternatively, the physical feedback can also depend on another variable related to the status of the grinding rollers, such as power consumption. This refers to the power consumption of a rotary drive that sets the first grinding roller and—generally at a different speed—the second grinding roller in rotation to grind the grain product in the grinding gap.

[0020] One possible form of physical feedback is the application of a controlled counter-torque or counter-force. The physical control element, e.g., a handwheel, can thus be configured to counteract the user's operation with a counter-torque (or counter-force), particularly when the grinding gap is reduced. Additionally or alternatively, the handwheel can also be configured to provide a tactile feedback signal, particularly in the form of pulses, so-called ticks. Neither of these options precludes the possibility of providing feedback, either additionally or alternatively, via a display.

[0021] In particular, the counter-torque – or counter-force – that must be overcome to move the rollers together can depend on the current width of the set grinding gap. It can increase with a smaller width, i.e., it can be larger, the smaller the grinding gap width (in single-sided operation: the width of the grinding gap on the relevant side).

[0022] In certain embodiments, the counter-torque for movement in the opposite direction can also be dependent on the width of the grinding gap, e.g. by being particularly small for small gap widths.

[0023] In embodiments, the increase in the counter torque as a function of the position upon approach of the grinding rollers can also be greater if the grinding gap is very small or the grinding rollers are in contact than with a larger grinding gap and / or the power consumption of the roller drive becomes very high due to the approach of the grinding rollers - i.e. the dependence of the counter torque on the gap width is not constant-linear in these embodiments. This has the consequence for the operator that they also physically feel that the grinding gap is closing. For example, depending on the width b of the grinding gap, there can be several segments in which the dependence of the force that must be applied to the operating element for the grinding rollers to approach each other differs from the width b (more precisely: from the current position of the electrically driven actuating element).Segments that correspond to a smaller grinding gap, or where the grinding rollers even physically touch each other (when stationary), can show a more pronounced, very strong dependence of the force on the position: the user feels that it almost cannot go any further.

[0024] Additionally or alternatively, the number of pulses per unit of movement (e.g., per angle of rotation) can also be increased, the smaller the width of the grinding gap. This can also be defined segment-wise if necessary.

[0025] It can also be provided that when a certain minimum gap width is reached and / or when a certain maximum power consumption is reached by the drive of the grinding rollers - e.g. when a maximum value is reached which lies between 90% and 99%, e.g. at 95% - a stop is formed by which the physical control element can no longer be moved, e.g. rotated, in the direction of the "smaller grinding gap".

[0026] Such a stop can be present, for example, at a gap width of 0 mm or at a negative value (set without load). A negative value for the minimum gap width can be useful because, under high forces, the inevitable play in the roller mill can cause the bearing bodies to be moved into positions that are closer together than the position they occupy when the grinding rollers are in contact with each other during a calibration process (not under load).

[0027] In particular, in contrast to the prior art, the roller mill can be configured to allow adjustment of the grinding gap from both a smaller and a larger grinding gap. This means that a certain gap width can be set by moving the grinding rollers towards each other after the grinding gap was previously larger than the value to be set, or conversely by moving the grinding rollers away from each other after the grinding gap was previously smaller. In this case, with a given calibration and a given operating mode, i.e., without intermediate switching, for example, between parallel and single-side operation, it can be provided that a specific (rotational) position of the physical control element corresponds to a specific distance between the first and second bearing bodies of the grinding rollers, regardless of the (rotational) direction of the last movement of the control element, i.e.When the control element is moved away from one position and back to it, the grinding rollers return to the same position, regardless of their previous position. In particular, a value for the grinding gap width stored in a data memory or manually entered can also be approached from a different grinding gap width.

[0028] The roller mill can in particular be designed to allow manual adjustment of the width of the grinding gap in parallel operation by parallel (coordinated and simultaneous, synchronous) operation of both electric drives when operating the physical control element.

[0029] This procedure has the substantial advantage that the adjustment of the grinding gap is both simpler and more reproducible compared to the state of the art. Once the grinding rollers are parallel, the operator can concentrate entirely on adjusting the gap width - in contrast to, for example, existing solutions with mechanical adjustment, where the operator must always pay careful attention to ensuring that the parallelism is readjusted with each fine adjustment. The roller mill - i.e. in particular its control unit - can furthermore be configured, in addition to parallel operation in one-sided operation, to also enable manual adjustment of the width of the grinding gap on one side only, by operating only one of the electric drives when operating the physical control element.

[0030] For example, switching can be carried out between a first state (parallel operation) and a second state (single-sided operation, only one electric drive is controlled via the physical control element, e.g., only the drive to the left of the grinding rollers) and, for example, also a third state (single-sided operation, only the other electric drive is controlled via the physical control element, e.g., only the drive to the right of the grinding rollers). Such switching between states can be carried out purely electronically, via a user interface (e.g., a touch-sensitive screen) of the roller mill or an external component, via a dedicated function of the physical control element (e.g., pressing the handwheel designed as a rotary / push wheel), or via another suitable input device, e.g., a rotary switch, slider, or the like.

[0031] In a roller mill with multiple roller packages, each with a pair of rollers, the same physical control element can also be used to adjust the width of multiple grinding gaps, i.e., the user can switch not only - if necessary - between parallel operation and single-sided operation, but also between different roller pairs. In particular, in an eight-roller roller mill, there can be exactly one physical control element (e.g., handwheel) at the front and rear, with which the grinding gaps of two superimposed roller pairs can be adjusted. Then, for example, at least six operating modes can be selected per control element (e.g., per handwheel): upper roller pair parallel, left, right; lower roller pair parallel, left, right. In embodiments, the roller mill is also configured to display an absolute reference independently of the physical control element.An absolute reference indicates the current position of the grinding rollers relative to each other. According to the current state of the art, such an absolute reference indication is linked to the handwheels themselves, for example, by providing a pointer display similar to an analog clock. Such an absolute reference is often required by operators – however, in the current state of the art, it is associated with the inaccuracies described above, and reading it is only possible with experience and knowledge of the calibration performed.

[0032] In contrast, in embodiments of the present invention, the display is provided via an output unit (e.g., a display) or an external device, whereby, for example, the width of the grinding gap can be displayed in absolute values ​​and in physically meaningful units, e.g., in millimeters. Due to the principle that the gap width is adjusted using electric drives, particularly servomotors, the roller mill never loses the absolute reference setting with a given calibration – it is retained even after extended periods of operation.

[0033] In embodiments, the roller mill is configured for automatic calibration. It is programmed such that, during calibration operation, the second grinding roller is moved relative to the first grinding roller, in particular without the grinding rollers rotating. This occurs until a contact criterion is reached, which indicates that the second grinding roller is touching the first grinding roller. For example, the torque applied by the servomotor can be measured and compared with a threshold value. Reaching the threshold value is considered the contact criterion. The rotational position of the electric drives (or, if applicable, equivalently: the position of the actuators) that applies when the contact criterion is met is stored and serves as a reference, for example as a zero position.The electric drive may belong to an actuating and disengaging device which has an actuating element whose position can be moved by the electric drive and whose position in turn determines the position of the second bearing body relative to the first bearing body.

[0034] The electric drive for moving the second bearing body relative to the first bearing body can be the only active drive for this movement, i.e., the only actuator that can move the second bearing body relative to the first bearing body on each side. The electric drive can therefore be the only active drive for influencing the position of the second bearing body relative to the first bearing body on each side—i.e., in some embodiments, the roller mill is particularly free of an automated release device in addition to the electric drive.

[0035] The electric drive can be formed by an electric motor and, if necessary, a gearbox. The electric motor can, in particular, be a servomotor. A 'servomotor' is understood here to be a motor that, through a sensor and possibly a control loop, allows the control of the rotational speed and, in many embodiments, also the angular position of the electric motor. The sensor does not necessarily have to be installed with the actual electric motor, but can also be installed separately, for example, on a shaft driven by the gearbox, such as the spindle described below.

[0036] During the grinding process, the grinding rollers are forced apart by the material to be ground. The adjusting and disengaging device can form a counterforce arrangement—optionally with the foreign body protection device—which exerts the corresponding counterforce to define the grinding gap during the grinding process. Furthermore, a preload spring can be provided, which permanently presses the first and second grinding rollers apart in order to preload the first and second bearing bodies against the counterforce arrangement formed by the adjusting and disengaging device. The preload spring can, for example, act on the first and second bearing bodies, i.e., there can be a preload spring on each side of the roller stack.

[0037] To form a counterforce arrangement, the adjusting and disengaging device has a first and a second stop structure, against which corresponding structures of the first and second bearing bodies press when the first and second grinding rollers are pressed apart. The preload spring, if necessary, ensures that the two grinding rollers are pushed away from each other not only by the product during the grinding process, but permanently. The adjusting and disengaging device accordingly permanently exerts a counterforce and presses the grinding rollers against each other via the first and second bearing bodies.

[0038] The actuating element can, for example, be movable by a spindle drive in such a way that the axial position is clearly determined by the revolutions of the spindle and ultimately of the electric drive (in particular servo motor).

[0039] For example, the roller set can be preloaded, with the preload preloading the second bearing body relative to the first bearing body in the direction that moves the second grinding roller away from the first grinding roller (preload in the disengagement direction). In this case, a first stop structure can be present on the adjusting and disengaging device, against which a portion of the first bearing body is pressed outwards, as well as a second stop structure, with which the second bearing body engages and against which the second bearing body is pressed outwards. The bearing bodies therefore tend to move outwards, away from each other - due to the material to be ground between the grinding rollers and also due to the preload. One of the two stop structures is assigned to the stop element and moves with it if necessary, and the other of the stop structures is assigned to the adjusting element and follows movements of the adjusting element relative to the stop element.The distance between the stop element and the adjusting element therefore determines the position of the second bearing body relative to the first bearing body.

[0040] The stop element can be stationary with respect to a frame or housing of the actuating and disengaging device, or it can also be movable like the actuating element, in particular along the axis.

[0041] The adjusting and disengaging device can also have a foreign body safety device. This allows the two grinding rollers to be moved apart against a comparatively strong spring force in order to prevent the grinding rollers from being damaged if a hard foreign body, for example a metal part, gets caught between the grinding rollers. In the prior art, the foreign body safety device is generally separate from the disengaging unit. In contrast, in embodiments of the present invention, the foreign body safety device is part of the adjusting and disengaging device. It can be provided that a preloaded spring device is present between the adjusting element and the (second or first) stop structure assigned to it and / or between the stop element and the (first or second) stop structure assigned to it.The relative movement of the bearing bodies when the grinding rollers move apart due to a foreign body can be qualitatively the same as when disengaging and adjusting the grinding gap. For the relative movements of the bearing bodies, there is, for example, only a single degree of freedom. In embodiments, the first and second bearing bodies are mounted fixedly to the housing with respect to a frame of the roller package. In particular, it can be provided that the first bearing body is fixed in its position and orientation relative to the frame, i.e., immovable, while the second bearing body can pivot about a pivot axis that is fixed with respect to the frame, immovable, and parallel to the roller axes. The first bearing body can, for example, be integral with the frame, i.e., can be formed by the frame.

[0042] In addition to the grinding rollers, the roller package can have a scraper, which during operation scraps off any material to be ground that adheres to the grinding rollers after passing through the grinding gap. It can be provided that the scraper is automatically lifted off the grinding rollers when the grinding rollers are disengaged. In one group of embodiments, this occurs in such a way that the scraper is lifted off when disengaged, but that the scraper is not influenced by a - generally very rapid - relative movement of the grinding rollers due to a foreign body. This also applies when, as described above, relative movements between the bearing bodies have only a single degree of freedom. For example, a lifting mechanism can be designed in such a way that a movement of the second bearing body relative to the first bearing body only occurs on a final section during disengagement, i.e.is only transferred to the lifting mechanism shortly before the grinding rollers have moved apart as far as possible.

[0043] In embodiments, the force transmission between the stop element and one bearing body (e.g. the first bearing body) and / or the force transmission between the actuating element and the other bearing body (e.g. the second bearing body) takes place via a universal joint-like connection, which enables a transmission of forces in the axial direction, but allows tilting in two different planes leading through the axis - generally perpendicular to one another.

[0044] In one group of embodiments, the roller assembly also has an optional bearing preload. This is designed to permanently preload the grinding rollers relative to their bearing bodies, i.e., the first grinding roller is preloaded relative to the first bearing body, and the second grinding roller is preloaded relative to the second bearing body. The grinding rollers are preloaded such that they are pushed away from each other and upward by a spring force. As a result, the grinding rollers are displaced away from each other by the radial clearance of their bearings, into the position they assume relative to their bearing body when they are pressed apart with great force during the grinding process.

[0045] Embodiments of the invention are described below with reference to drawings. In the drawings, like reference numerals designate like or similar elements. The drawings are partly schematic and not to scale. They show partly corresponding elements in different sizes from figure to figure. They show:

[0046] Fig. 1 : A partial view of a roller package for a roller mill;

[0047] Fig. 2 is a top view of part of the roller package of Fig. 1;

[0048] Fig. 3 a side view of the roller package;

[0049] Fig. 4 and 5 the roller package cut along the plane IV-IV and the plane VV in Fig. 2 respectively;

[0050] Fig. 6 is a view of the adjusting and disengaging device of the roller package; Fig. 7 is a sectional view of the adjusting and disengaging device;

[0051] Fig. 8 is a schematic representation of the displacement of the rollers relative to the bearing bodies with or without bearing preload;

[0052] Fig. 9 shows a schematic view of a roller mill according to the invention;

[0053] Fig. 10 a diagram with control unit;

[0054] Fig. 11 shows a force-position characteristic for a handwheel as the physical control element; and

[0055] Fig. 12 Characteristic curves for the calibration process.

[0056] Figure 1 shows a view of a roller assembly 1, of which only one side is shown. Figure 2 shows a top view of one side of the roller assembly, and Figure 3 shows a side view of the roller assembly. Figures 4 and 5 show the roller assembly sectioned along planes IV-IV and VV (Fig. 2), respectively, with a drive housing of the actuating and disengaging device shown in elevation.

[0057] The roller assembly comprises a first grinding roller 2 and a second grinding roller 3. The first and second grinding rollers each have a roller stub 21, 31 on the side, which is rotatably supported by a first bearing 22 and a second bearing 32, respectively.

[0058] A frame 4 forms a supporting structure and can be attached to a roller mill frame or forms part thereof. A first bearing body 5 and a second bearing body 6 are present or mounted on the frame 4. In the illustrated embodiment, the first bearing body 5 is formed by the frame itself, thus forming part of it. The second bearing body 6 is pivotally mounted on the frame 4, with the pivot axis defined by a pivot pin 7 and being fixed to the frame and thus also to the housing with respect to the roller mill.

[0059] The first bearing body 5 and the second bearing body 6 are pressed apart by a preload spring 10, so that they are permanently preloaded. An adjusting and disengaging device 40 exerts a counterforce against this spring force and, during the grinding process, also against the force exerted by the material to be ground and transmitted from the grinding rollers to the bearing bodies, which pushes the grinding rollers apart. For this purpose, the adjusting and disengaging device 40 has a stop structure on each of its two sides with force transmission elements described below. An electric drive can exert a force between the two stop structures and move the stop structures towards each other against the aforementioned forces pushing the first bearing body 5 and the second bearing body 6 apart, thus moving them from a disengaged position to an engaged position.The electric drive can also enable and / or actively drive a reverse movement of the bearing bodies away from each other.

[0060] The actuating and disengaging device 40 is shown somewhat enlarged in Figures 6 and 7. It has a drive housing 41 with an electric drive motor 42, namely a servomotor, which is only shown schematically in the figures. This drives a spindle 44, which is arranged in a spindle housing 47, via an optional gear 43, which is also only shown schematically. A spindle nut 45, which interacts with the spindle 44, is thereby moved in the axial direction together with a shaft 46, which is firmly connected to the spindle nut. At the end of the shaft there is a fixing 48, which is, for example, screwed to the shaft and can also be glued to secure the screw. The unit comprising the spindle nut 45, shaft 46 and fixing 48 together forms an actuating element within the meaning of the present text, i.e.The position of this unit along axis 70 relative to the stop element is uniquely determined by the electric drive, namely the drive motor 42. The connection between spindle nut 45 and shaft 46 can be a screw connection, possibly with additional bonding; other connections are also possible.

[0061] Between the fixation 48 and a second force transmission member 49 there is a disc spring arrangement 55 which is compressed between the fixation 48 and the second force transmission member 49, whereby it is preloaded and presses the second force transmission member 49 permanently against a stop 58 formed by the spindle housing 47.

[0062] In addition to the second force transmission member 49, the actuating and disengaging device 40 has a second intermediate member 50 cooperating with the second intermediate member 50, as well as, toward the other end, a first force transmission member 52 and a first intermediate member 53. The first force transmission member 52 is firmly connected to the spindle housing 47 and, in the illustrated embodiment, is even integral with it, so that the spindle housing 47 and the first force transmission member 52 are formed by a common component.

[0063] The first force transmission element 52 acts - in the example shown together with the spindle housing 47 - as a stop element in the sense of the present text.

[0064] The first and second intermediate members 50, 53 are permanently pressed away from each other and against the first and second force transmission members 52, 49 by the preload of the roller stack and, during operation, also by the grinding rollers themselves. They have the second stop structure and the first stop structure, respectively, in the illustrated embodiment in the form of the first cutting edges 71 and second sheaths 72, respectively, which will be described below.

[0065] The force is transmitted between the first and second bearing bodies 5, 6 on the one hand and the actuating and disengaging device 40 on the other hand via the first and second force transmission members 52, 49 and the first and second intermediate members 53, 50, and is angularly movable in the manner of a universal joint on each side. The connection between the first bearing body 5 and the first intermediate member 53 as well as the connection between the second bearing body 6 and the second intermediate member 50 allows relative tilting in the vertical plane. In addition, with the described arrangement with the universal joint-like connections, tilting about a second tilting axis is also possible, which is approximately vertical in the configuration shown. For this purpose, the universal joint-like connection has first cutting edges 71 formed on the first intermediate member 53, which engage in corresponding beads 81 in the first bearing body 5.Accordingly, second cutting edges 72 are provided on the second intermediate link 50, which engage in beads 82 in the second bearing body 6. In addition, third cutting edges 73 and fourth cutting edges 74 are provided on the first and second intermediate links 53, 50, respectively, which engage in beads on the first force transmission link 52 and the second force transmission link 49, respectively. The third cutting edges and fourth cutting edges 73, 74 are arranged at a position offset by 90° (with respect to the axis 70 of the actuating and disengaging device 40) relative to the first cutting edges 71 and second cutting edges 72, respectively, so that they enable slight tilting out of the vertical plane leading through the axis 70, i.e. tilting about the approximately vertical second tilting axis perpendicular to the axis 70.

[0066] If a foreign body gets between the grinding rollers and thereby briefly pushes the first and second grinding rollers apart with great force, the second bearing body 6 can move the second force transmission element together with the first force transmission element 49 away from the stop 58 against the spring force of the disc spring arrangement 55. The drive train with servo motor, possibly gearbox, spindle, and spindle nut remains unaffected.

[0067] In the illustrated embodiment, the disengagement or engagement movement, the fine adjustment of the width of the grinding gap and the foreign body protection all take place on a common axis - the axis 70 of the adjusting and disengaging device 40 - i.e. during all these movements, elements of the adjusting and disengaging device 40 (namely the stop structures with the force transmission members) move towards or away from each other along the axis 70 while they are in engagement with the first or second bearing body 6.

[0068] As is known per se, the stripper, which acts on the grinding roller(s) during operation to strip off adhering ground material, is also to be lifted off the grinding rollers during the disengagement process. For this purpose, the roller package has a lifting mechanism with a pivoting lever 91 that can be pivoted about a pivot point 92 and is connected to the second bearing body 6 via a joint 93 and a flat lever 94. If the second bearing body 6 is moved away from the first bearing body, the pivoting lever 91 is accordingly taken along and pivoted about the pivot point 92. On the underside, the pivoting lever 91 has an elongated hole 95 into which a driving pin 96 engages. The movement of this hole - to the left in Figure 3 - lifts the stripper off the grinding rollers 5, 6 against a spring force. The stripper can, for example, be designed as described in Swiss patent application 000831 / 2022.

[0069] When the grinding rollers are moved away from each other, the resulting pivoting movement of the pivot lever 91 initially does not engage the driving pin 96, since the elongated hole is dimensioned and arranged such that the pivot lever can move relative to the driving pin 96. Only towards the end of the pivoting movement of the pivot lever 91 does the driving pin 96 strike a driving surface (in Fig. 3, on the right at the elongated hole 95) and is carried along to lift the scraper. Consequently, the scraper is only lifted when the grinding rollers are disengaged, in which the adjusting and disengaging device 40 causes the two stop structures to move completely apart into the disengaged position.

[0070] In embodiments, the roller assembly also has a bearing preload. This is designed to permanently push the grinding rollers 2, 3 outward relative to their bearing bodies 5, 6, i.e., away from each other, and upward. The grinding rollers are therefore permanently in the position relative to their bearing bodies in which they are as far apart as possible. This is schematically shown – for the first grinding roller 2 – in Figure 8, in which the circle shown schematically represents the radial play for the roller stub in its bearing. Without bearing preload, when the roller mill is not in operation, a first, underside position 111 is assumed due to the grinding rollers' own weight. When the grinding rollers are pushed apart during operation, however, they are in a second, lateral position 112 relative to their bearing.Due to the bearing preload, the grinding rollers are pressed in the direction of the arrow shown, i.e. into the second position 112, even when stationary, which is why the position is always defined and essentially unchangeable relative to the bearing and thus to the bearing body, even during a calibration process.

[0071] In the illustrated embodiment, the bearing preload is achieved as follows: An additional bearing preload ball bearing is provided on each side of each roller (in addition to the one that supports the shaft stub relative to its bearing body), e.g., a deep groove ball bearing. A plurality of spring assemblies 101, each with a stop surface 102 oriented radially inward by a spring force, push the outer ring of the bearing preload ball bearing outward and upward—directly or indirectly, e.g., via a sleeve 103, 104.

[0072] Figure 9 shows a very schematic view of the entire roller mill 201 with at least one roller stack. A handwheel 202 serves as the electronically readable physical control element. Additional input and output options may be available, which are indicated in Fig. 9 by a schematic display panel 203—which may be touch-sensitive—an input panel 204, and an interface to a mobile phone 205. It is also possible that additional physical control elements are present on the roller mill and / or that additional or different interfaces are available.

[0073] The handwheel 202 can be a rotary-push type control element, meaning that in addition to rotation, an axial movement of the handwheel is also possible and is electronically detected. The axial movement can, for example, cause a position to be saved, a fixation, or another action, depending on the programming and, for example, as shown in the display field 203.

[0074] Figure 10 shows a very schematic view of a control unit 210 of the roller mill, which is configured to individually control the servomotors 42 of the two actuating and disengaging devices of the roller stack—and, if multiple roller stacks are present, corresponding to the servomotors of each actuating and disengaging device. Control is performed based on the user input on the handwheel 202, which is read electronically. However, it also occurs—complementarily or alternatively—based on other inputs, e.g., a setting 221 between the operating modes "left" (only the first servomotor M1 is controlled), "parallel" (both servomotors are controlled), and "right" (only the second servomotor M2 is controlled), based on stored data 222, e.g., so-called "recipes," and / or based on user input, e.g., via an external device (mobile phone 205).

[0075] Figure 11 shows a possible force-position characteristic to which the handwheel can be programmed. Depending on the width b of the grinding gap (in single-sided operation, depending on the width b on the corresponding side), the force (torque) F with which the user must operate the handwheel to move the rollers towards each other increases segment-by-segment linearly, i.e., proportional to (c s -b), where c s is a constant that can vary from segment to segment.

[0076] In the illustrated embodiment, the dimensions of the segments 230 decrease with a smaller width b of the grinding gap. Furthermore, the curves become steeper when the grinding rollers are close to each other or even touch each other, i.e., for segments 230 corresponding to smaller widths b, the proportionality constant is larger.

[0077] Furthermore, the number of pulses per angle of rotation—that is, per unit length by which the grinding gap is adjusted—can also depend on the width b of the grinding gap and, for example, vary from segment to segment. In particular, more pulses per angle of rotation can be generated for segments 230, which correspond to smaller grinding gap widths (left in Fig. 11).

[0078] The handwheel can be adjusted to allow relatively fine adjustment of the grinding gap. One revolution of the handwheel can, for example, correspond to a difference in the grinding gap (in parallel operation; in single-sided operation, to the width of the grinding gap at the corresponding axial end of the grinding rollers) of between 0.05 mm and 0.2 mm, in particular between 0.08 mm and 1.5 mm, for example approximately 0.1 mm. The width of the segments 230 can correspond to more than one revolution of the handwheel. A disengaged position (which does not have to be reached by turning the handwheel, but is approached by an independent disengagement process) corresponds to a grinding gap width of at least approximately 5 mm.

[0079] In addition to the segments 230, an electronically adjusted stop 231 can also be provided for the rotation of the handwheel. Turning the handwheel beyond this stop can no longer be possible without excessive force being applied. Such a stop can be located, for example, at a nominal gap width of less than 0. This means that upon reaching the stop, the grinding rollers generally touch each other with considerable force, so that the gap width, which is nominally less than 0, can be achieved. The distance between the zero value and the stop value can depend, for example, on whether or not a bearing preload is present.If there is no bearing preload, the adjusting elements and, with them, the bearing bodies can still be moved a greater distance in the engagement direction when the two grinding rollers are already touching than if there is bearing preload and there are only small tolerances by which the adjusting elements can still be moved in the engagement direction (i.e., toward the stop element in the example shown) when the grinding rollers are touching. In general, a negative value of the gap width b can be considered a measure of the force with which the grinding rollers are pressed against each other.

[0080] A calibration process can provide for the non-rotating grinding rollers to be slowly moved towards each other, starting from a holding position in which they are safely spaced apart, until a predetermined criterion (contact criterion) is met that is meaningful for physical contact between the grinding rollers - for example, exceeding a threshold value Ms for the required drive torque of the servo motors. Figure 12 shows this schematically for a first characteristic curve 241, as it is characteristic for an embodiment with bearing preload, and a flatter second characteristic curve 242, as it can result when no bearing preload is present. The position of the servo drives when the contact criterion is reached is stored and remains even after subsequent processes, such as the disengagement and re-engagement of the

[0081] This applies to grinding rollers and grinding processes with potentially different products. The calibration process only needs to be repeated after extended operation, during which the grinding rollers may wear out, or after replacing the grinding rollers, e.g., for maintenance purposes.

Claims

PATENT CLAIMS 1. Roller mill (201) for milling grain, comprising a first grinding roller (2) and a second grinding roller (3), wherein the first grinding roller (2) is mounted on both sides by a first bearing body (5) and the second grinding roller (3) is mounted on both sides by a second bearing body (6), wherein the second bearing body (6) is movable on both sides relative to the first bearing body (5) by a respective electric drive, and wherein the roller mill is configured to move the second grinding roller (3) relative to the first grinding roller (2) by moving the second bearing body (6) relative to the first bearing body (5) in order to adjust a width of a grinding gap between the first grinding roller (2) and the second grinding roller (3), characterized by an electronically readable, physical operating element, wherein the roller mill is configured to effect a movement of at least one of the electric drives depending on a movement of the physical operating element.

2. Roller mill according to claim 1, wherein the physical operating element is configured to generate physical feedback upon operation.

3. Roller mill according to claim 1 or 2, wherein the physical feedback depends on a status of the roller mill.

4. Roller mill according to claim 2 or 3, wherein the physical feedback depends on a current width of the grinding gap and / or on a current power consumption of a rotary drive of the first grinding roller and the second grinding roller.

5. Roller mill according to one of claims 2-4, wherein the physical operating element is configured to counteract an operation of the operating element with a counter-torque or a counter-force.

6. Roller mill according to claim 5, wherein the counter-torque or counter-force is greater when the grinding gap is narrower than when it is wider.

7. Roller mill according to one of claims 2-6, wherein a movement of the physical control element results in physical feedback in the form of pulses, the number of pulses per unit of movement being dependent in particular on the width of the grinding gap.

8. Roller mill according to one of the preceding claims, wherein a movement of the electric drives is proportional to a movement of the physical operating element.

9. Roller mill according to one of the preceding claims, wherein the physical operating element is a handwheel (202).

10. Roller mill according to one of the preceding claims, wherein a dependency of user feedback on a rotational position of the electric drives is adjustable.

11. Roller mill according to one of the preceding claims, which is arranged to allow a manual adjustment of a width of the grinding gap in a parallel operation enable coordinated operation of both electric drives depending on operation of the physical control element.

12. Roller mill according to one of the preceding claims, which is designed to enable manual adjustment of the width of the grinding gap only on one side in a one-side operation by operating only one of the electric drives when operating the physical control element.

13. Roller mill according to claim 12, which is designed to enable the manual adjustment of the width of the grinding gap on one side or only on the other side in a single-side operation by operating only one or only the other electric drive when operating the physical control element.

14. Roller mill according to one of the preceding claims, which is arranged to move the second grinding roller (3) relative to the first grinding roller (2) in a calibration operation until a contact criterion is reached which indicates that the second grinding roller (3) touches the first grinding roller (2), and that a rotational position of the electric drives can be stored when the contact criterion is reached in order to serve as a reference.

15. Roller mill according to claim 14, wherein the contact criterion is the achievement of a predetermined counter-torque against further movement of the second grinding roller (3) relative to the first grinding roller (2).

16. Roller mill according to one of the preceding claims, which is arranged to output an absolute width of the grinding gap via an output unit or an interface to an external device.

17. Roller mill according to one of the preceding claims, wherein the electric drive is configured to effect, on the basis of control signals, both a movement of the second bearing body (6) relative to the first bearing body from an engaged to a disengaged state independently of an actuation of the physical operating element and, depending on the actuation of the physical operating element, the movement of the second bearing body into the engaged state relative to the first bearing body for adjusting the width of the grinding gap.

18. Roller mill according to one of the preceding claims, wherein the electric drive comprises a servo motor.

Images