Arrangement and method for detaching an adhering charge from an inner wall of a grinding tube

Abstract

An arrangement and method for detaching an adhering charge from an inner wall of a grinding tube, wherein the grinding tube is rotated backwards in a drive-free manner from a pre-determinable, assumed rotary position by the weight force of the adhering charge, where at least one movement state variable of the grinding tube is detected and the grinding tube is braked while being rotated back in dependence on the at least one detected movement state variable in order to detach the adhering charge from the inner wall of the grinding tube, and where the arrangement includes a detecting device, a drive unit, a braking device and a control device.

Claims

1. A method for releasing an adhering charge from an inner wall of a grinding tube, the method comprising: rotating the grinding tube backwards autonomously from a pre-determinable rotational position adopted by said grinding tube, with no drive, due to a weight force of the adhering charge, at least one movement state variable of the grinding tube being detected during the autonomous backwards rotation; and braking the grinding tube, during the autonomous backwards rotation, as a function of the at least one movement state variable to release the adhering charge from the inner wall of the grinding tube.

2. The method as claimed in claim 1, wherein the pre-determinable rotational position is reached by a driven rotation, for which a drive facility of the grinding tube is utilized.

3. The method as claimed in claim 1, wherein the pre-determinable rotational position of the grinding tube is pre-determined as a rotational angle determined as a function of a characteristic of the charge.

4. The method as claimed in claim 1, wherein the pre-determinable rotational position of the grinding tube is pre-determined as a rotational angle with a magnitude of between 40 and 90 starting from a stable position of equilibrium.

5. The method as claimed in claim 1, wherein the at least one movement state variable which is detected is at least one of a rotational angle, an angular rotational speed and an angular rotational acceleration of the grinding tube.

6. The method as claimed in claim 1, wherein the grinding tube is braked to a halt at least once during the backwards rotation.

7. The method as claimed in claim 1, wherein the grinding tube is braked at least once with a pre-determinable deceleration during the backwards rotation.

8. The method as claimed in claim 7, wherein the pre-determinable deceleration is determined as a function of a characteristic of the charge.

9. The method as claimed in claim 7, wherein the pre-determinable deceleration is determined as a function of a mechanical stress limit for the grinding tube.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained in further detail below with reference to an exemplary embodiment and figures in which:

(2) FIG. 1 shows a schematic representation of a tube mill with a grinding tube, onto the inner wall of which adheres an adhering charge;

(3) FIG. 2 shows a schematic structure of a control or regulation arrangement, as applicable, for detaching an adhering charge from the inner wall of a grinding tube in accordance with the invention;

(4) FIG. 3 shows a graphical plot of a rotational angle against time, with corresponding graphs of the activities of a drive and a brake in accordance with the invention;

(5) FIG. 4 shows another graphical plot of a rotational angle against time, with corresponding graphs of the activities of a drive and a brake in accordance with the invention;

(6) FIG. 5 shows a schematic representation of a typical drive facility for the powered rotation of a grinding tube in accordance with the invention;

(7) FIG. 6 shows a schematic representation of a tube mill in plan view in accordance with the invention;

(8) FIG. 7 shows a schematic representation of another tube mill in plan view in accordance with the invention;

(9) FIG. 8 shows a further schematic representation of another tube mill in plan view; and

(10) FIG. 9 is a flowchart of the method in accordance with the invention.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

(11) FIG. 1 shows a schematic representation of a tube mill 2, such as is used, for example, for grinding ore. The tube mill 2 has a structural framework 4, a regular cylindrical grinding tube 6 and an arrangement 8 with a drive facility 10, a braking facility 12 (obscured by the drive facility 10), a detection facility 14 and a control facility 16.

(12) The grinding tube 6 has a bearing mount in the structural framework 4 that allows rotation of the grinding tube 6 about an axis of rotation 18, and is shown in section to improve the view. The grinding tube 6 has an inner wall 20. In the interior of the grinding tube 6 and adhering to its inner wall 20 is an adhering charge 22.

(13) The adhering charge 22 or the grinding tube 6, as applicable, is in a rotational position 28, rotated about a rotational angle 26 from a position of equilibrium 24. In the rotational position 28, a weight force 30 is effective that applies at a center of gravity 32 of the adhering charge 22. The weight force 30 produces a restoring torque about the axis of rotation 18.

(14) During normal operation of the tube mill 2, the drive facility 10 drives the grinding tube 6 in rotation. A charge that is not adhering (not shown here) is consequently broken into smaller pieces by impact, pressure and shear forces, which are transmitted between the charge itself, on the inner wall 20 and by any spheres or cylinders (grinding bodies) that may be present. If the grinding operation of the tube mill 2 is interrupted for a sufficiently long time period, it can happen as described in the introduction that adherence of the charge onto the inner wall 20 of the grinding tube 6, as shown in FIG. 1, comes about.

(15) In the case shown here, with a charge 22 adhering to the inner wall 20 of the grinding tube 6, an unwanted collapse of the adhering charge 22 can occur when the grinding tube 6 is driven by the drive facility 10 beyond a certain rotational position, such as a rotational position in the quantitative range of 90 to 180, as a consequence of the detaching weight force 22 that then applies more strongly. Here, the angular rotation that can lead to a collapse of the adhering charge 22 is dependent, among other factors, on a characteristic 34 of the charge, such as a level of filling of the grinding tube 6 or a material property of the adhering charge 22.

(16) The detection facility 14 is equipped for determining the current angular rotation 26 or the current rotational position 28, as appropriate, an angular rotational velocity 36 and/or an angular rotational acceleration 38 of the grinding tube 6. The detection facility has a magnetic wheel sensor 15 which, as shown in FIG. 1, need not necessarily be an integral component of the detection facility, but can also be arranged separately from the detection facility.

(17) The braking facility 12 is constructed such that the grinding tube 6 can be braked as a function of the angular rotational velocity 36 and/or the angular position 28 or the angular rotation 26, as appropriate. The braking facility 12 is constructed to transmit to the grinding tube 6 a braking pressure, a braking force and/or a braking torque. Apart from this, the braking facility 12 is constructed such that the braking pressure, the braking force and/or the braking torque can be controlled or regulated. That is, the braking facility 12 is constructed to be actuated by the control facility 16.

(18) The control facility 16 is set up to control or regulate, as appropriate, the braking pressure, the braking force and/or the braking torque as a function of the angular rotational velocity 36, the charge characteristic 34 and/or the angular rotational acceleration 38 of the grinding tube 6.

(19) For the purpose of releasing the adhering charge 22 from the inner wall 20 of the grinding tube 6, the drive facility 10 moves the grinding tube 6, starting from the position of equilibrium 24, into the rotational position 28, where the rotational position 28 can have a functional dependence on the characteristic 34 of the charge. Here, the rotational position that is driven to can of course also be in a direction of rotation opposite to that shown in FIG. 1. What is decisive is only the magnitude of the angular rotation 26.

(20) After the rotational position 28 has been reached, and the switching off or uncoupling, as applicable, of the drive facility 10, the grinding tube 6 rotates drive-free (autonomously) (as a result of the weight force 30 or the restoring torque resulting from the weight force 30 and the rotational axis 18) in the direction of the position of equilibrium 24, opposite to the direction of rotation due to the drive. The detection facility 14 detects, particularly during the autonomous rotation of the grinding tube 6 from the rotational position 28, the rotational angle 26 that establishes itself, the angular rotational velocity 36 and/or the angular rotational acceleration 38 of the grinding tube 6.

(21) Depending on the angular rotational velocity 36 thus detected, the control facility 16 controls the braking pressure or the braking force or the braking torque, as applicable, of the braking facility 12 on the grinding tube 6 such that an expedient braking of the grinding tube 6 results. The braking of the grinding tube 6 results in an inertial force of the adhering charge 22, with a detaching effect on the adhering charge, so that a detachment of the adhering charge 22 from the inner wall 20 of the grinding tube 6 advantageously results.

(22) The grinding tube 6 is braked, in particular, as a function of the characteristic 34 of the charge. That is, for example, depending on the characteristic 34 of the charge, the braking facility 12 brakes the grinding tube as rapidly as possible down to a standstill, or with a pre-determinable angular rotational acceleration 38, or a pre-determinable deceleration 48, as appropriate. In addition, the pre-determinable deceleration 48 can be oriented in accordance with a mechanical stress limit for the grinding mill 2. In this manner, it is possible to ensure that no mechanical overloading of the braking facility 12 or of the tube mill 2, as appropriate, arises from excessively strong braking.

(23) If, after braking of the grinding tube 6 has been effected once, no detachment of the adhering charge 22 has occurred, the procedure can be repeated until the grinding tube 6 has reached the position of equilibrium 24 or until the restoring torque generated by the weight force 32 is no longer sufficient to set the grinding tube 6 into an autonomous rotation.

(24) After an unsuccessful rotation back into the equilibrium position 24, the grinding tube 6 can once again be rotated into the rotational position 28, preferably into a rotational position with greater rotation, and the further process steps for releasing the adhering charge 22 can be executed once again.

(25) FIG. 2 shows a schematic structure of a control or regulation arrangement 8, as applicable, for the detachment of an adhering charge 22 from the inner wall 20 of a grinding tube 6 (20, 22 see FIG. 1).

(26) The arrangement 8 has a drive facility 10, a braking facility 12, a detection facility 14 and a control facility 16.

(27) For the purpose of releasing an adhering charge 22 from the inner wall 20 of the grinding tube 6, the detection facility 14 detects at least one movement state variable 40 of the grinding tube 6. The at least one movement state variable 40 or the movement state variables 40, as applicable, is/are preferably a rotational angle 26, an angular rotational velocity 36 and/or an angular rotational acceleration 38 that the grinding tube 6 will adopt under an autonomous weight-force induced rotation.

(28) A value of the at least one movement state variable 40 is communicated as a measurement signal 42 to the control facility 16.

(29) Via a control signal 44, the control facility 16 actuates the braking facility 12 as a function of the at least one movement state variable 40, preferably as a function of the angular rotational velocity 36 and the angular rotational acceleration 38.

(30) The braking facility 12 brakes the grinding tube 6 selectively by an application of a braking torque 46 (also: braking-pressure, -force), where the braking torque 46 can be regulated or at least controlled as a function of the movement state variable 40, preferably the angular rotational acceleration 38, detected by the detection facility 14.

(31) A pre-determinable deceleration 48 is stored as a data item or a value, as applicable, in the control facility 16. The pre-determinable deceleration 48 can be a temporarily constant value, or one that can be changed over time, which in particular is dependent on a charge characteristic 34 of the adhering charge 22 (22, 34 see FIG. 1). The charge characteristic 34 is input into the control facility 16 in the form of an input value 50, which can also be a set of values, or is detected by it. Here, the input value 50 will preferably relate to material-specific characteristics of the adhering charge 22 and/or to a level of filling of the grinding tube 6.

(32) The braking facility 14 brakes the grinding tube, or is actuated by the control facility 16 via the control signal 44, such that the pre-determinable deceleration 48 is not exceeded (in the case of an upper limiting value) or is at least reached (in the case of a lower limiting value), as applicable.

(33) If an adequately high angular rotational acceleration 38 (deceleration) is achieved as a result of the braking, for the reasons described in the introduction this causes a detachment of the adhering charge 22 from the inner wall 20 of the grinding tube 6.

(34) At a point in time before this, the grinding tube 6 is rotated by a driving torque 52 (also: driving force), applied by the drive facility 10, into an expedient rotational position. The rotation occurs, as described in the introduction, against a restoring torque from the adhering charge 22 and is controlled by the control facility 16 via a control signal 54.

(35) Here, the actuation of the drive facility 10 by the control facility is preferably effected as a function of the charge characteristic 34 of the adhering charge 22, i.e., as a function of the input value 50. That is, the rotational position that is to be adopted is determined as a function of the input value 50 or is in some other manner stored in the control facility 16 as a pre-determinable rotational position 56.

(36) FIG. 3 shows a diagram with a graphical plot of a rotational angle 26 (ordinate []) for a grinding tube 6 against time 58 (abscissa [s]) during the detachment of an adhering charge 22 from an inner wall 20 of a grinding tube 6 (6, 20, 22 see FIG. 1). Also shown are corresponding graphs of a drive activity 60 (ordinate []) and a braking activity 62 (ordinate []), each against time 58, where the three time axes shown are identical.

(37) Starting from a position of equilibrium 24 of the grinding tube 6 (see, e.g., FIG. 1) in a rotational position 64 at point in time 66, the grinding tube 6 is rotated by a drive activity 68 into a rotational position 70 at a point in time 72. During the drive activity 68, between the time points 66 and 72, a drive torque 52 (see, e.g., FIG. 2) is transmitted to the grinding tube 6 (see, e.g., FIGS. 1, 2), where no explicit graph of the drive torque 52 is reproduced at this point for purposes of clarity.

(38) After a switch-off of the drive activity 68 at the time point 72, the grinding tube rotates autonomously, as explained above, as a result of the weight force of the adhering charge, in the opposite direction of rotation from that previously effected by the drive activity 68. In the course of this, the angular rotational speed increases.

(39) At a point in time 74, a braking activity 76 effects a sharp braking of the grinding tube, where the grinding tube comes to a halt in a rotational position 78. During the braking activity 76, between the time points 74 and 80, a braking torque 46 (see, e.g., FIG. 2) is transmitted to the grinding tube 6 (see, e.g., FIGS. 1, 2), where the explicit graph of the braking torque 46 is not reproduced at this point for purposes of clarity. The braking activity 76 is terminated at a time point 80, whereupon the grinding tube 6 once again starts to rotate autonomously and accelerates. Here, the detectable angular rotational acceleration is smaller, by comparison with the angular rotational acceleration of the original backwards rotational movement at the time point 72, as a consequence of the now reduced restoring torque due to lever arm of the adhering charge 22.

(40) At a later point in time 82, another sharp braking of the grinding tube 6 is effected by another braking activity 84, where the grinding tube comes to a halt at a rotational position 86. The braking activity 84 is terminated at a time point 88, where the grinding tube does not this time autonomously start to rotate, but pauses with the charge now detached in the rotational position 86.

(41) FIG. 4 shown a further diagram with a graphical plot of the rotational angle 26 (ordinate []) of a grinding tube 6 against time 58 (abscissa [s]) during the detachment of an adhering charge 22 from an inner wall 20 of a grinding tube 6 (6, 20, 22 see FIG. 1). Also shown in turn are corresponding graphs of a drive activity 60 (ordinate [) and a braking activity 62 (ordinate []), shown in each case against time 58, wherein the three time axes shown are identical.

(42) Starting from a position of equilibrium 24 of the grinding tube 6 (see, e.g., FIG. 1) in a rotational position 90 at a point in time 92, the grinding tube 6 is rotated by a drive activity 94 into a rotational position 96 at a time point 98.

(43) After a switch-off of the drive activity 94 at the time point 98, the grinding tube 6 rotates autonomously, as explained in the introduction, as a result of the weight force of the adhering charge, in the opposite direction of rotation from that previously effected by the drive activity 94. In the course of this, the angular rotational speed increases.

(44) At a point in time 100, a braking activity 102 effects a braking of the grinding tube 6 until it reaches a pre-determinable deceleration 48 (see, e.g., FIG. 2), where the grinding tube 6 comes to a halt in a rotational position 104. That is, unlike the exemplary embodiment shown in FIG. 3, the grinding tube 6 is not braked sharply but in a carefully regulated manner. The braking activity 102 is initiated at a rotational position 106 and preferably as a function of the angular rotational speed 36 detected at this time point (see, e.g., FIGS. 1, 2). The braking activity 102 is terminated at a time point 108, whereupon the grinding tube 5 once again starts to rotate autonomously until at the time point 110 the position of equilibrium 24 (see, e.g., FIG. 1) is once again reached, or the rotational position 90 is reached without the detachment of the adhering charge 22, as applicable.

(45) A detachment of the adhering charge 22 from the inner wall 20 of the grinding tube 6 is effected by a renewed drive activity 112 between the time points 110 and 114, an autonomous acceleration of the grinding tube between the time points 114 and 116, and a further braking activity 118 between the time points 116 and 120. As a consequence, after the termination of the braking activity 118 there is no renewed rotation of the grinding tube, but the grinding tube pauses in the rotational position 104.

(46) FIG. 5 shows a schematic view of a typical drive facility 10 for the driven rotation of a grinding tube 6. The drive facility 10 has a main drive 122, a main gearbox 124, an auxiliary drive 126, an auxiliary gearbox 128, two auxiliary clutches 130 and a main clutch 132. The braking facility 12 is arranged between the auxiliary drive 126 and the auxiliary gearbox 128, where the braking facility 12 can also be arranged in another position or structurally separated from the drive facility 10. The drive facility 10 works on a ring gear 134, which can be arranged on a circumference of the grinding tube 6.

(47) FIG. 6 shows a schematic diagram of a tube mill 2a in plan view. The tube mill 2a has a grinding tube 6 that has a bearing mount so that it can rotate about an axis of rotation 18, a drive facility 10a with a main drive 122a and a main gearbox 124a. The drive facility 10a works on the ring gear 134. In addition, the tube mill 2a has several braking facilities 12a. These are mounted between the main drive 122a and the main gearbox 124a, on the drive offtake side on the main gearbox 124a and on the ring gear 134.

(48) FIG. 7 shows a schematic diagram of another tube mill 2b in plan view. The tube mill 2b has a grinding tube 6 that has a bearing mount so that it can rotate about an axis of rotation 18, a drive facility 10b with a main drive 122b and a main gearbox 124b, an auxiliary drive 126a and an auxiliary gearbox 128a. The drive facility 10b works on the ring gear 134. In addition, the tube mill 2b has several braking facilities 12b. These are mounted between the main drive 122b and the main gearbox 124b, on the drive offtake side on the main gearbox 124b, between the auxiliary drive 126a and the auxiliary gearbox 128a, on the drive offtake side on the auxiliary gearbox 128a and on the ring gear 134.

(49) FIG. 8 shows a schematic diagram of another tube mill 2c in plan view. The tube mill 2c has a grinding tube 6 that has a bearing mount so that it can rotate about an axis of rotation 18, a drive facility 10c with a main drive 122c, a main gearbox 124c, an auxiliary drive 126b and an auxiliary gearbox 128b. Here, the main gearbox 124c of the drive facility 10c works directly on the ring gear 134. In addition, the tube mill 2c has several braking facilities 12c. These are mounted between the main drive 122c and the main gearbox 124c, between the auxiliary drive 126b and the auxiliary gearbox 128b, on the auxiliary drive 126b and on the ring gear 134.

(50) FIG. 9 is a flowchart of the method for releasing an adhering charge (22) from an inner wall (20) of a grinding tube (6). The method comprises rotating the grinding tube (6) backwards from a pre-determinable rotational position (28) adopted by said grinding tube (6), with no drive, due to a weight force (30) of the adhering charge (22), as indicated in step 910.

(51) Here, at least one movement state variable (40) of the grinding tube (6) is detected.

(52) Next, during the backwards rotation, the grinding tube (6) is braked as a function of the at least one movement state variable (40) which has been detected to release the adhering charge (22) from the inner wall (20) of the grinding tube, as indicated in step 920.

(53) Thus, while there have been shown, described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those element steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.