AU2014363719B2

AU2014363719B2 - Roller mill and assembly for driving a roller mill

Info

Publication number: AU2014363719B2
Application number: AU2014363719A
Authority: AU
Inventors: Axel Furst
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2013-12-12
Filing date: 2014-12-08
Publication date: 2018-02-01
Anticipated expiration: 2034-12-08
Also published as: CL2016001356A1; AU2014363719A1; EP3079825A1; EP2883612A1; WO2015086486A1; PE20161460A1; CA2932845A1

Abstract

The subject matter of the invention is that a roller mill with a displaceable roller (1') is driven via an electric motor (2) with a rotor (21) which is mounted so as to be displaceable in an axial direction. Here, the displaceable roller (1') is mounted in an axial direction and in a radial direction. A cardan shaft (3) with a constant length is arranged between the electric motor (2) and the displaceable roller (1') such that the rotary movement of the rotor (21) can be converted into a rotary movement of the displaceable roller (1'). In the case of a displacement of the displaceable roller (1') orthogonal to the axial direction of the displaceable roller (1'), joints of the cardan shaft balance out the resulting angular displacement of the shaft of the displaceable roller (1') and the shaft of the electric motor (2). The resulting change in the distance between the shaft of the displaceable roller (1') and the shaft of the electric motor (2) is balanced out by the rotor (21) by an axial movement.

Description

DESCRIPTION

Roller mill and assembly for driving a roller mill

TECHNICAL FIELD

The present invention relates to the field of roller mills. It concerns a roller mill having two contrarotating rollers which are rotatably mounted in a frame, and an

assembly for driving	such a	roller	mill.
PRIOR ART
Roller mills	are	used	for grinding	materials,	in
particular ores	and	cement.	Roller	mills	typically have	a
roller diameter	of 0	. 8 to 3	meters	and a	driving power	of

0.2 to 5 megawatts. They are particularly energy-efficient by comparison with other types of mill. Such a roller mill is described, for example, in DE 4028015 Al.

As is diagrammatically illustrated in figure 1, a roller mill comprises two contrarotating rollers 1, 1', which rollers 1, 1' are rotatably mounted horizontally and parallel to one another in a frame. Here, one of the two rollers 1 is generally fixed in the radial direction and another of the two rollers 1' is pressed onto the fixed roller 1 by means of a spring system. Each roller 1, 1' has a grinding surface. The opposite grinding surfaces of the rollers 1, 1' form a wedge. Material is filled from above between the rollers 1, 1' into the wedge, guided downward as a result of the rotation of the rollers 1, 1' and comminuted through the wedge. The rotation of the rollers 1, 1' is achieved by means of a drive. In the case of known drives for roller mills, an electric motor is

2014363719 05 Jan 2018 indirectly connected via movable mechanical elements to one of the rollers or to both rollers.

Figure 2 shows a roller mill having two drives. One drive is assigned to each of the rollers 1, 1' and comprises an electric motor 2, a cardan shaft 3 and a planetary gear mechanism 4. The radially displaceable roller 1' is connected to the positionally fixed electric motor 2 via the cardan shaft 3. Optionally, it is also possible for the cardan shaft to be directly connected to the shaft of the displaceable roller and for the planetary gear mechanism to be arranged between the cardan shaft and the electric motor. In such an arrangement, as described, for example, in DE 10211000749 Al, the electric motor and the planetary gear mechanism are positionally fixed. Optionally, it is also possible to use one motor and one gear mechanism to drive both rollers. In this case, the gear mechanism distributes the torque between both rollers. Optionally, it is also possible for the electric motor to deliver the desired rotational speed for the rollers without rotational speed adaptation of a gear mechanism. In this case, the drive comprises no gear mechanism and the electric motor is directly connected to the roller via the cardan shaft.

Figure 3 shows two rollers having one drive each. Displacement of the displaceable roller 1' results in the shaft of the positionally fixed electric motor 2 and the shaft of the displaceable roller 1' no longer being aligned. The radial displacement between the shafts is compensated for by movements in joints 31 of the cardan shaft 3. Since the displaceable shaft 1' is displaced substantially orthogonally to the axial direction, the distance between the joints 31 of the cardan shaft 3 increases. The necessary adaptation of the length of the

2014363719 05 Jan 2018 cardan shaft 3 is achieved by means of a telescopic mechanism 32.

Figure 4 shows a cardan shaft having a telescopic mechanism. Here, the cardan shaft 3 has, between the joints 31, a rectilinear spur toothing 32 which is displaceable in the axial direction of the cardan shaft 3. This makes it possible for the cardan shaft 3 to have a variable length and be able to transmit a torque. A problem with this solution is that a cardan shaft having a telescopic mechanism is very expensive and maintenanceintensive. The sliding surfaces of the toothing must always be lubricated. On account of the very dirty and dusty working environment, which working environment is caused by the grinding process, very frequent maintenance, such as, for example, in a weekly cycle, is necessary. Otherwise, there is insufficient lubricant present on the toothing and there occurs massive abrasion and wear through friction in the region of the toothing. However, even with sufficient maintenance, cardan shafts having telescopic mechanisms in this arrangement in roller mills prove to be susceptible to faults owing to notch effects and the axial movement in a confined space and often lead to the failure of the mill.

Figure 5 shows a displaceable roller 1' with an associated drive. The displaceable roller 1' has a radial bearing arrangement 11 and an axial bearing arrangement 12. Alternatively, it is also possible for one of the radial bearings to be put together with the axial bearing in a combined axial-radial bearing. An electric motor 2 has a rotor 21 and a stator 22. The rotor is mounted by means of a radial bearing arrangement 23 and an axial bearing arrangement 24. A cardan shaft 3 connects the displaceable shaft 1' to the rotor 21 of the electric motor 2. The

2014363719 05 Jan 2018 necessary adaptation of the length of the cardan shaft 3 during a displacement of the displaceable shaft 1' is achieved by means of a telescopic mechanism 32.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

SUMMARY OF THE INVENTION

Throughout this specification the word comprise, or variations such as comprises or comprising, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

According to a first aspect, the present invention provides a roller mill comprising two contrarotating rollers which are arranged in parallel and pressed against one another, wherein one of the rollers is displaceable orthogonally to the axial direction of this roller, and wherein the displaceable roller is mounted in the axial and radial direction and comprises a drive, which drive comprises an electric motor and a cardan shaft, wherein the electric motor comprises a rotor and a positionally fixed stator, and wherein the cardan shaft is arranged between the rotor and the displaceable roller in such a way that the cardan shaft can transmit a rotary movement of the rotor to the displaceable roller, wherein the rotor is mounted so as to be displaceable in the axial

2014363719 05 Jan 2018 direction, and in that the cardan shaft has a length which is nonvariable during operation of the roller mill.

According to second aspect, the present invention provides an assembly for driving a roller mill having a displaceable roller, which displaceable roller is displaceable orthogonally to the axial direction of the displaceable roller, wherein the assembly comprises an electric motor and a cardan shaft, wherein the electric motor comprises a rotor and a positionally fixed stator, and wherein the cardan shaft can be arranged between the rotor and the displaceable roller in such a way that the cardan shaft can transmit a rotary movement of the rotor to the displaceable roller, wherein the rotor is mounted so as to be displaceable in the axial direction, and the cardan shaft has a nonvariable length.

The aim of the present invention is to make available a roller mill and an assembly for driving a roller mill which are preferably less maintenance-intensive and less susceptible to faults.

In an advantageous embodiment a displaceable roller of a roller mill is connected via a cardan shaft of nonvariable length to an electric motor. The displaceable roller is mounted in the axial and radial direction. The electric motor has a rotor which is displaceable in the axial direction. This floating mounting of the rotor of the electric motor makes it possible to compensate for the change in the distance between the positionally fixed stator of the electric motor and the displaceable shaft owing to displacements of the displaceable shaft orthogonally to the axial direction of the displaceable shaft without the use of a telescopic mechanism and using a cardan shaft with a constant length. This allows a

2014363719 05 Jan 2018 simpler construction with a lower maintenance requirement and a lower susceptibility to faults.

BRIEF DESCRIPTION OF THE FIGURES

The invention will be explained in more detail below with reference to exemplary embodiments in conjunction with the figures, in which:

figure 1	shows a schematic illustration of the grinding process of a roller mill according to the prior art ;
figure 2	shows a perspective illustration of a roller mill having two drives according to the prior art ;
figure 3	shows two rollers with one drive each according to the prior art in a plan view;
figure 4	shows a cardan shaft with a telescopic mechanism according to the prior art in a plan view;
figure 5	shows a schematic illustration of an axial section through a displaceable roller with a drive according to the prior art; and
figure 6	shows a schematic illustration of an axial section through a displaceable roller with a drive according to the invention.

The reference signs used in the drawings are summarized in the list of reference signs. In principle, identical parts are provided with the same reference signs.

WAYS OF IMPLEMENTING THE INVENTION

Figure 6 shows a displaceable roller with a drive according to the invention. The displaceable roller 1' has a radial bearing arrangement 11 and an axial bearing

2014363719 05 Jan 2018 arrangement 12. An electric motor 2 has a rotor 21 and a stator 22. The rotor 21 is guided via a radial bearing arrangement 23 in such a way that the rotor 21 is displaceable in the axial direction. A cardan shaft having a fixed length during operation of the roller mill connects the displaceable shaft to the electric motor 2. Optionally, it is possible for the axial bearing arrangement of the drive to be arranged on the cardan shaft or the rotor instead of on the displaceable roller. Optionally, it is possible for the drive to have a gear mechanism, such as, for example, a planetary gear mechanism, in which case the gear mechanism is arranged between the cardan shaft and the displaceable roller. The gear mechanism is mounted such that no movement occurs relatively between the gear mechanism and the displaceable roller and the gear mechanism experiences the same movements orthogonally to the axial direction of the displaceable roller as the displaceable roller itself. Optionally, it is possible that the cardan shaft has, outside of the operation of the roller mill, an adjustable length, for example in the form of a telescopic mechanism with a locking screw.

2014363719 05 Jan 2018

LIST OF REFERENCE SIGNS

1,1'

Roller

Radial bearing Axial bearing Electric motor

Rotor

Stator

Radial bearing Axial bearing Cardan shaft

Joint

Spur toothing Planetary gear of the roller of the roller of the rotor of the rotor mechanism

2014363719 05 Jan 2018

Claims

CLAIMS :

1. A roller mill comprising two contrarotating rollers which are arranged in parallel and pressed against one another, wherein one of the rollers is displaceable orthogonally to the axial direction of this roller, and wherein the displaceable roller is mounted in the axial and radial direction and comprises a drive, which drive comprises an electric motor and a cardan shaft, wherein the electric motor comprises a rotor and a positionally fixed stator, and wherein the cardan shaft is arranged between the rotor and the displaceable roller in such a way that the cardan shaft can transmit a rotary movement of the rotor to the displaceable roller, wherein the rotor is mounted so as to be displaceable in the axial direction, and the cardan shaft has a length which is nonvariable during operation of the roller mill.
2. The roller mill as claimed in claim 1, wherein the roller mill comprises a gear mechanism, which gear mechanism is arranged between the displaceable roller and the cardan shaft and is mounted so as to be displaceable orthogonally to the axial direction of the

2014363719 05 Jan 2018 displaceable roller in such a way that the gear mechanism is positionally fixed relative to the displaceable roller.
3. The roller mill as claimed in claim 2, wherein the gear mechanism is a planetary gear mechanism.
4. The roller mill as claimed in any one of claims 1 to 3, wherein the radial bearing arrangement of the rotor has two sliding bearings.
5. An assembly for driving a roller mill having a displaceable roller, which displaceable roller is displaceable orthogonally to the axial direction of the displaceable roller, wherein the assembly comprises an electric motor and a cardan shaft, wherein the electric motor comprises a rotor and a positionally fixed stator, and wherein the cardan shaft can be arranged between the rotor and the displaceable roller in such a way that the cardan shaft can transmit a rotary movement of the rotor to the displaceable roller, wherein the rotor is mounted so as to be displaceable in the axial direction, and the cardan shaft has a nonvariable length.

2014363719 05 Jan 2018
6. The assembly as claimed in one of claims 5, wherein the radial bearing arrangement of the rotor has two sliding bearings.

1/5

Fig. 1 Prior Art

2/5

3/5

Fig. 3

Prior Art

CO

4/5 to <

* u O it ‘C

5/5

CO ίΖ