Roller mill introduction device, roller mill and method for determining the level of grinding material

Abstract

The invention relates to an inlet device (1) for a roller mill, comprising a material storage box (2), a force sensor (6) arranged at the material storage box (2), a level sensor (7) arranged at the material storage box (2) for determining a material level (B) of a milled material in the material storage box (2), and a control unit (8). According to the invention, the control unit (8) is designed to determine a first material level (A) of the material storage box (2) based on a gravity (EG) determined by the force sensor (6) and to determine a characteristic level curve (K) based on the determined first material level (A) and the material level (B) determined by the level sensor (7).

Description

Technical Field

[0001] The invention relates to an inlet device for a roller mill, a control unit for the inlet device and a roller mill having an inlet device according to the invention. The invention also relates to a method for determining a roller mill filling level and controlling the grinding material filling level of a storage box of a roller mill. Background Art

[0002] In the roller mill of the prior art, upstream of the respective grinding passage, the grinding material is for example supplied to the storage box by gravity and is deposited there. Then, the grinding material is metered and sent into the grinding gap by a discharge device such as a feed roller.

[0003] At the start of the grinding operation, the filling level of the storage box is first set to the target filling level, for example manually by the operator. It must be considered that there is sufficient free buffer volume (fill level as low as possible) on the one hand, and on the other hand, the grinding material can be metered over the entire length of the roller (fill level as high as possible).

[0004] During operation, the deviation between the actual material level and the target material level is detected by a measuring device (e.g. a force sensor). The control device ensures that the discharge is regulated so that the actual material level corresponds as closely as possible to the target material level. Force sensors have the disadvantage that the level of the grinding material is not measured directly but indirectly and thus has to be calibrated, which depends largely on the properties of the material to be ground, in particular its density.

[0005] The disadvantage of such a measuring device is that the actual filling level measured by the measuring device may not correspond to the actual filling level of the tank. Therefore, the operator must always manually check the actual filling level and calibrate the determined actual filling level. Summary of the invention

[0006] Therefore, the object of the present invention is to provide an introduction device for a roller mill, a control unit for the introduction device, a roller mill and a method for determining the filling level of a storage box, which avoid the disadvantages of the prior art and in particular enable the filling level of the storage box to be determined simply, cheaply and automatically.

[0007] This object is achieved by an introduction device, a control unit, a roller mill and a method having the features of the independent claims.

[0008] It should be noted here that within the meaning of the present invention, a roller mill is understood to be a roller device which can be used not only in the milling industry but also for other foods and animal feed.

[0009] The introduction device comprises a storage box having at least one grinding material inlet and at least one grinding material outlet.

[0010] The introduction device further comprises at least one metering device, which is arranged at the storage box and is used for metering the grinding material entering the grinding gap of the roller mill through the grinding material outlet.

[0011] The metering device can be simply designed as a gap, wherein, if necessary, the discharge amount can be adjusted by changing the gap width (e.g., by means of a throttle valve). The metering device can further include other components, which for example support the distribution of the milled material in the storage box. These other components can include, for example, a conveying device such as a paddle or a worm. The metering device can also include a feed roller, which is designed to convey the milled material from the milled material outlet to the milling gap of the roller mill.

[0012] This metering device can be arranged downstream of the storage box, that is, between the grinding gap and the storage box. Alternatively or additionally, it can be provided that this metering device is arranged upstream of the storage box, so that the grinding material amount conveyed into the storage box can be metered.

[0013] A force sensor is arranged at the storage bin to determine the weight force exerted by the material to be ground.

[0014] A filling level sensor is also arranged at the storage box to determine when the grinding material filling level has been reached.

[0015] The fill level sensor therefore provides a true value as to whether the fill level in the storage tank has reached the grinding material level and possibly exceeded it.

[0016] The force sensor and / or the level sensor can be arranged outside or inside the storage box. For example, the storage box can be connected to the force sensor, for example suspended from the force sensor or mounted on the force sensor. According to the invention, only the weight force exerted by the milled material in the storage box and the milled material level need to be determined.

[0017] The filling level sensor is preferably arranged in the storage box, particularly preferably in the upper half of the storage box.

[0018] The force sensor is preferably arranged in the storage box, particularly preferably in the lower region of the storage box.

[0019] This means that the force sensor is arranged in such a way that the gravity force can be determined when the filling level of the storage bin is low and the grinding material does not reach the filling level sensor until the storage bin has been filled to at least half of its capacity.

[0020] The introduction device further comprises a control unit which is connected or connectable to the force sensor and the fill level sensor.

[0021] The control unit can be a dedicated control unit for the introduction device, which is connected to a higher-level control unit, for example, of the roller mill. This is particularly advantageous if the introduction device is used to retrofit an existing roller mill. Alternatively, the control unit can be implemented in a higher-level control unit, for example in the control unit of the roller mill or in the plant control system.

[0022] According to the invention, the control unit is designed to determine the first filling level of the tank as a function of the weight force determined by the force sensor.

[0023] The control unit is further designed to determine a characteristic fill level curve based on the determined first fill level and the grinding material fill level determined by the fill level sensor.

[0024] The first material level is preferably a predetermined material level corresponding to the installation height of the force sensor.

[0025] As already mentioned above, the fill level determined with the aid of a force sensor depends on many factors, in particular on the density of the grinding material.

[0026] The control unit can therefore initially report the filling level of the storage tank, since the determination of the gravity means that there is material to be ground in the storage tank and, if the force sensor is arranged in the storage tank, it is exposed to the material to be ground.

[0027] Alternatively, since the determined weight is related to the fill level, any fill level may be used and, for example, an initial fill level curve and a gravity-fill level correlation may be used to determine the initial first fill level.

[0028] The initial fill level curve can be determined using only the measured gravity. Alternatively, it can be provided that the operator can input parameters about the ground material, such as the grinding degree of the ground material, the roller gap width of the upstream channel, etc., which are used to determine the initial fill level curve.

[0029] Level sensors also determine whether the ground material has reached a certain level.

[0030] Based on this, the control unit can determine the characteristic filling level curve in a simple manner, preferably by interpolation and / or extrapolation, using the reached filling level and the first filling level.

[0031] In the characteristic fill level curve, the gravity values ​​are respectively assigned to the fill level values.

[0032] This means that manual adjustments between the measured actual fill level and the actual fill level can be dispensed with, since this is now performed by the control unit.

[0033] Preferably, the characteristic level curve is determined when the grinding material level is reached. Particularly preferably, the characteristic level curve is also determined for levels above the grinding material level.

[0034] The control unit can be designed in particular such that the characteristic level curve is newly determined each time the grinding material level is reached. If the level drops below the grinding material level, the characteristic level curve continues to be used, wherein if the level rises and the grinding material level is reached again, a new characteristic curve is determined.

[0035] Alternatively or additionally, provision can also be made for the characteristic level curve to be re-determined when the filling level falls below the grinding material level. When the filling level decreases, the filling level sensor can be used to determine whether the filling level falls below the grinding material level and thus determine the characteristic level curve.

[0036] In this sense, "reaching the grinding material level" means, according to the invention, reaching the grinding material level when the level increases and / or falling below the grinding material level when the level decreases.

[0037] Preferably, the control unit is further adapted to determine, after determining the characteristic fill level curve, a second fill level based on the determined gravity and the characteristic fill level curve.

[0038] This can increase the accuracy of the fill level determination since each weight value is assigned to a fill level value with the aid of the characteristic fill level curve.

[0039] Preferably, the vertical distance between the force sensor and the level sensor is between 20 cm and 80 cm, more preferably between 40 cm and 60 cm.

[0040] Preferably, the fill level sensor is designed as a capacitive sensor.

[0041] Capacitive sensors are a particularly simple, durable and cost-effective way to determine material levels.

[0042] The invention also relates to a control unit for an inlet device of a roller mill. All advantages and further developments of the inlet device described above therefore also apply to the control unit according to the invention.

[0043] The control unit is connected or connectable to a force sensor arranged on the storage box for determining the weight force exerted by the milled material, and the control unit is connected or connectable to a level sensor arranged on the storage box for determining when the milled material level is reached in the storage box.

[0044] The control unit is further designed to determine a first filling level of the storage tank as a function of the weight force determined by the force sensor and to determine a characteristic filling level curve based on the determined first filling level and the grinding material level determined by the filling level sensor.

[0045] The invention also relates to a roller mill having an inlet device according to the invention. Therefore, all advantages and further developments of the above-described inlet device can also be applied to the roller mill according to the invention accordingly.

[0046] The roller mill comprises at least two rollers, which define a roller gap for grinding a grinding material, the grinding material being supplied to the roller gap from a grinding material outlet of the introduction device.

[0047] The invention also relates to a method for determining the filling level of a storage bin of a grinding material of a roller mill. Therefore, all advantages and further developments of the above-described introduction device, control unit and roller mill also apply accordingly to the method according to the invention.

[0048] In this case, a storage box comprises at least one grinding material inlet, at least one grinding material outlet and at least one metering device for metering the grinding material through the grinding material outlet into the grinding gap of the roller mill.

[0049] The method according to the invention comprises the following steps:

[0050] First, the weight force exerted by the milled material is determined using a force sensor located on the storage bin.

[0051] A first filling level of the storage tank is then determined based on the weight force determined by the force sensor.

[0052] The reaching of the grinding material level in the storage tank is determined by means of a filling level sensor arranged on the storage tank.

[0053] A characteristic fill level curve is subsequently determined based on the determined first fill level and the grinding material fill level determined by the fill level sensor.

[0054] As described above, the method according to the invention can therefore be carried out by a simple sensor device. The weight force determined by the force sensor is correlated with the filling level of the storage tank. The filling level can therefore be determined by this correlation.

[0055] The level sensor also determines whether the ground material has reached a certain level.

[0056] Based on this, the characteristic filling level curve can be determined simply by determining the filling level curve with the aid of the reached filling level and the first filling level, preferably by interpolation and / or extrapolation.

[0057] The filling level curve is then used to determine a second filling level of the tank, the gravity of which is determined by the force sensor.

[0058] This means that manual adjustments between the measured actual fill level and the actual fill level can be dispensed with, since this is now performed by the control unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] The present invention will be better described below with reference to preferred embodiments in conjunction with the accompanying drawings, in which:

[0060] Figure 1is a schematic cross-sectional view of an introduction device according to the present invention; and

[0061] Figure 2 It is a schematic diagram of the characteristic material level curve. DETAILED DESCRIPTION

[0062] Figure 1 The introduction device 1 is schematically shown. The introduction device 1 comprises a storage box 2 with a grinding material inlet 3 and a grinding material outlet 4. A metering device 5 is also arranged at the grinding material outlet 4, which is designed as a throttle valve. The gap width of the grinding material outlet 4 can be changed by rotating the throttle valve. A force sensor 6 is arranged at the storage box 2, which comprises an extension arm 9, which extends into the storage box 2 and can be designed as a bending beam, for example.

[0063] When the storage bin 2 is filled with material to be ground, a cone of material to be ground is formed, which is schematically indicated by a dashed line. Once the cone of material to be ground reaches the extension arm 9, a gravity force FG is applied to the latter. The control unit 8 is connected to the force sensor 6 (schematically indicated by a dashed line 10) and thus detects that a first material level A has been reached in the storage bin.

[0064] As the storage bin 2 is filled further, the ground material cone and thus the fill level in the storage bin increases. The increase in the fill level in the storage bin 2 is detected by the control unit 8 via the increase in the weight force F determined by the force sensor 6. The control unit 8 can therefore use the initial characteristic fill level curve K2 (e.g. Figure 2 The initial material level is determined by the dotted line.

[0065] When the grinding material cone reaches the level sensor 7, a signal is transmitted to the control unit 8 via the connection 11 (also schematically shown as a dashed line) to indicate that a level corresponding to the grinding material level B has been reached. The control unit 8 can therefore use the first level A and the grinding material level B to determine the characteristic level curve K, such as Figure 2 Shown schematically.

[0066] The fill level curve K (and similarly the initial fill level curve K2) relates the measured weight force F (x-axis) to the fill level FS (y-axis). Figure 2 It can be seen that the fill level curve K can be used by the control unit 8 to determine the fill level FS of the storage tank 2 for each weight force F determined by the force sensor 6, which fill level FS is more accurate than the fill level determined only by the temporary fill level curve K2, because the fill level curve K has been calibrated by using the fill level B. Therefore, manual adjustment of the actual measured fill level with the actual fill level of the storage tank 2 can be omitted.

Claims

1. An introduction device (1) for a roller mill, comprising: a storage tank (2) having at least one inlet (3) for grinding material and at least one outlet (4) for grinding material, at least one metering device (5) arranged in the storage box (2) for metering the ground material into the grinding gap of the roller mill through the ground material outlet (4), a force sensor (6) arranged at the storage box (2) for determining the weight force (FG) exerted by the grinding material, - a control unit (8) connected or connectable to said force sensor (6), Characterized in that the introduction device also includes: a level sensor (7) arranged at the storage tank (2) for determining when a grinding material level (B) has been reached in the storage tank (2), And the control unit (8) is connected or can be connected to the level sensor (7), and the control unit (8) is designed to determine the first level (A) of the storage box (2) from the gravity (FG) determined by the force sensor (6), wherein the control unit (8) is also designed to determine the characteristic level curve (K) based on the determined first level (A) and the grinding material level (B) determined by the level sensor (7).

2. The introduction device (1) according to claim 1, characterized in that When the grinding material level (B) is reached, the characteristic level curve (K) is determined.

3. The introduction device (1) according to any one of the preceding claims, characterized in that The control unit (8) is further designed to determine a second filling level after determining the characteristic filling level curve (K) based on the determined gravity (F) and the characteristic filling level curve (K).

4. The introduction device (1) according to claim 1 or 2, characterized in that: The vertical distance between the force sensor (6) and the material level sensor (7) is between 20 centimeters and 80 centimeters.

5. The introduction device (1) according to claim 1 or 2, characterized in that: The material level sensor (7) is a capacitive sensor.

6. The introduction device (1) according to claim 1 or 2, characterized in that: The characteristic filling level curve (K) is determined by interpolation and / or extrapolation.

7. The introduction device (1) according to claim 1 or 2, characterized in that: The material level sensor (7) is arranged in the material storage box (2).

8. The introduction device (1) according to claim 1 or 2, characterized in that: The force sensor (6) is arranged in the storage box (2).

9. The introduction device (1) according to claim 8, characterized in that The force sensor (6) is arranged in the lower region of the storage box (2).

10. A control unit (8) for an induction device (1) according to any one of the preceding claims, characterized in that The control unit (8) is connected or can be connected to a force sensor (6) arranged at the storage box (2) for determining the gravity (FG) exerted by the milled material, and is connected or can be connected to a level sensor (7) arranged at the storage box (2) for determining the milled material level (B) reached in the storage box (2), wherein the control unit (8) is also designed to determine a first level (A) of the storage box (2) based on the gravity (FG) determined by the force sensor (6) and to determine a characteristic level curve (K) based on the determined first level (A) and the milled material level (B) determined by the level sensor (7).

11. A roller mill (14) comprising at least two rollers defining a gap, characterized in that The roller mill further comprises an introduction device (1) according to any one of claims 1 to 9.

12. A method for determining the grinding material level of grinding material in a storage box (2) of a roller mill, the storage box comprising at least one grinding material inlet (3), at least one grinding material outlet (4) and at least one metering device (5), the metering device being used to meter the grinding material entering the grinding gap of the roller mill through the grinding material outlet (4), the method comprising the following steps: - determining the weight force (FG) exerted by the material to be ground by means of a force sensor (6) arranged in the storage box (2), - determining a first filling level (A) of the storage tank (2) based on the weight force determined by the force sensor (6), - determining, by means of a level sensor (7) arranged at the storage tank (2), that a grinding material level (B) has been reached in the storage tank (2), - determining a characteristic level curve (K) based on the determined first level (A) and the grinding material level (B) determined by the level sensor (7).

13. The method according to claim 12, characterized in that The characteristic filling level curve (K) is determined by interpolation and / or extrapolation.

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