RU2848035C1 - Mill with friction multi-motor drive - Google Patents

Abstract

FIELD: mining industry.

SUBSTANCE: invention relates to devices for grinding ore and other materials and can be used, for example, in the mining, cement, energy, metallurgical, lime, porcelain and chemical industries. A mill with a friction multi-motor drive comprises racks (6), support-drive units (4) in the form of double-armed levers, for example in the form of two remotely located plates (21), in which a pair of support-drive rollers (26) are installed, which are driven by electric motors (11), rims (3) of predominantly cylindrical shape, rigidly connected, for example, to the end caps (2) of the drum (1) and in contact with the support-drive rollers (26). Rollers (31) are installed mainly at the edges of the plates (21) with the possibility of contact with the ends of the rim (3). The rim (3) is made in the form of sectors with fastening elements (16) to the end caps (2) of the drum (1), for example, by means of two ties (14) having a conical section that contacts a ring-shaped conical section formed on the end caps (2) of the drum (1), which are fastened with bolts (15). The joint of the rim sectors (3) is made at an angle of 5…15 degrees to the rim axis (3). The end cover (2) of the drum (1) is made of sectors connected to each other mainly by wedge ties (17).

EFFECT: self-alignment of the support and drive assemblies (4) relative to the rim (1), which, in particular, reduces friction losses and increases the service life of the mill.

8 cl, 6 dwg

Description

The proposed technical solution applies to devices for crushing ore and other materials and can find application in, for example, the mining, cement, energy, metallurgy, lime, porcelain, and chemical industries. Furthermore, the proposed technical solution can be applied, for example, to cement kilns, tumbling drums, drying drums, etc.

In principle, these mills operate using two different systems. In the case of so-called neck mills, in which the mill body rests on support bearings consisting of roller or plain bearings, the mill is driven by motors, which, via gears and clutches, transmit the required power to the mill body via gears and toothed rings located outside the mill body. When the drum is mounted on rollers, it is rotated by motors that drive the rollers, which then transmit the required power to the mill body via a friction drive. In this latter case, the rollers act as both a support and a drive for the mill.

Hybrid forms of the two main groups of mills are also available, such as gear-driven mills which rely on non-driven rollers, and tube mills which, as described in EP 0500509, contain non-driven rollers and a central motor.

An analogue of the claimed technical solution is the patent for invention US 3818777 A "Supports for large-diameter drums and drive means for rotating the drums", containing running belts (rims), including at least one support and a drive device consisting of a combination of: a support roller with a cylindrical surface in contact with the belt, held by a device for self-centering the axis of said roller with the axis of the belt; at least one toothed ring coaxial with said roller; drive means; a device for transmitting motion to the toothed ring, with at least one drive element, driven by said drive means, which is in engagement with the toothed ring. The disadvantage of this design is the presence of a hydraulic motor, which requires the use of a hydraulic station, the presence of toothed engagement complicates the design and reduces the working life, and the ratio of the width of the roller to its diameter is significantly less than one and a half, requiring the use of a mechanism for self-centering the axis of the roller with the axis of the belt.

The closest to the claimed technical solution is the patent for invention RU 2830697 C1 "Mill with a friction multi-motor drive", containing cylindrical rims rigidly connected, for example, to a drum, support and drive rollers installed on both sides of at least one cylindrical rim, driven into rotation by electric motors located coaxially with the support and drive rollers, at least on two racks connected, for example, to a steel frame of the mill foundation, installed with the possibility of swinging: support and drive units, which are double-arm levers, made, for example, in the form of two remotely located plates, in which, essentially symmetrically to the axis of swing, a pair of support and drive rollers is installed, or additional double-arm levers, in which two support and drive units are already installed with the possibility of swinging, or additional double-arm levers, in which two of the above-mentioned additional units are already installed with the possibility of swinging two-arm levers, in which two support and drive units are installed, thereby forming a support of a friction multi-motor drive, containing one, or two, or four support and drive units. Moreover, in the center of the support and drive roller, a substantially cylindrical section is formed, the surface of which contacts the cylindrical surface of the rim, and the cylindrical section is limited by conical flanges protruding from the plates and limiting the axial movement of the rim, wherein the outer diameter of the flange is substantially equal to the outer diameter of a spherical double-row rolling roller bearing and a groove for an oil seal is made in the flange, and along the edges of the support and drive roller, cylinders are formed, the diameter of which is equal to the inner diameter of the spherical double-row rolling roller bearing, which prevent the support and drive roller itself from axial movement, and the bearings themselves are prevented from axial movement, for example, by projections made in the holes of the plates. The main design flaw is the presence of sliding friction between the rim and the conical flanges on the drive and support rollers, which reduces their service life and increases power loss due to friction, similar to the case with railway car wheels, which are decommissioned when the flange is thinned to 20 mm. Furthermore, the welded rim connection to the disc limits the choice of rim material, as it must have good weldability.

The technical objective of the proposed technical solution is to eliminate the above-mentioned shortcomings, increase the service life of the mill, and improve maintainability.

The technical problem is solved by using a mill with a friction multi-motor drive, comprising racks, support and drive units consisting of double-arm levers, such as two spaced plates, in which a pair of support and drive rollers, driven by electric motors, are mounted substantially symmetrically to the oscillation axis. The rims are predominantly cylindrical and rigidly connected, for example, to the end caps of the drum and contacting the support and drive rollers. The rollers are primarily mounted along the edges of the plates, allowing them to contact the rim ends. This ensures self-alignment of the support and drive units relative to the rim, reducing friction losses and increasing the mill's service life.

The rim is designed as a sector with fastening elements to the drum end caps, such as two clamps with a conical section that contacts an annular conical section formed on the drum end caps, which are bolted together. This design ensures repairability, meaning the rim can be replaced directly at the customer's site, and also increases the choice of material, ensuring maximum wear resistance after heat treatment, since the mechanical fastening of the rim eliminates welding.

The rim sectors are joined at an angle of 5 to 15 degrees to the rim axis. This reduces mill noise and extends service life. The minimum angle of 5 degrees is selected based on the maximum permissible loss of contact line between the support roller and the rim when moving from one rim sector to another, while the maximum angle of 15 degrees is limited by the additional material consumption associated with manufacturing the rim element-by-element on machining centers rather than from a ring.

The rollers are mounted on rolling bearings in a cage rigidly connected to the drive-support unit plate. A catch on the housing contacts the plate surface on the rim side. The difference in roller protrusion beyond the plate surface on the rim side is no more than 0.3 mm, and the distance between the rollers and the rim is 0.5–3 mm. This design solution reduces the tolerance range for roller protrusion beyond the plate surface to no more than 0.3 mm, ensuring minimal non-parallelism between the drive-support roller axis and the rim axis, which reduces friction losses. The uniformity of roller protrusion beyond the inner surface of the drive-support unit plates and the distance between the rollers is controlled by installing metal shims between the inner surface of the plates and the catch on the roller housing. Exceeding the distance between the rollers relative to the rim width by 0.5 mm ensures the assembly of the mill, and the maximum distance of 3 mm limits the maximum angle of rotation of the support and drive unit relative to the rim axis.

The joints between the rim sectors are 0.5–2 mm. The minimum dimension of 0.5 mm is determined by the difference in thermal expansion between the rim and the drum end cap, while the maximum dimension of 2 mm is determined by the maximum tolerances required for manufacturing the rim sectors.

A hole is typically drilled in the center of the rim section for a pin connected to the drum end cap. This measure can be used if the rim sections begin to shift relative to the drum end cap during operation.

The drum end cap is made of sections, connected primarily by wedge ties. Dividing the drum end caps into sections is necessary for large-diameter mills due to transportation requirements, and connecting them with wedge ties eliminates the need for welding.

The invention is explained in more detail by drawings, where:

Fig. 1 shows the mill in isometric view without part of the fence and with a removed sector of the rim;

Fig. 2 shows a front view of the stand as part of the mill;

Fig. 3 shows a section of the rim with its fastening details;

Fig. 4 shows a section of the end covers of the drum along the ties;

Fig. 5 shows a bottom view of the support and drive unit as part of the mill;

Fig. 6 shows an isometric view of the support and drive unit;

Fig. 1 shows a mill containing a drum 1, end covers 2 (Fig. 1-4) of the drum 1 (Fig. 1), rims 3 (Fig. 1, 2, 3, 5), consisting of sectors that rest on support and drive units 4 (Fig. 1, 2, 5, 6), mounted on levers 5 (Fig. 1, 2, 5) with the possibility of swinging, and the levers 5 themselves are also mounted with the possibility of swinging on posts 6, connected to each other by transverse 7 (Fig. 1, 2) and longitudinal 8 (Fig. 1) plates. On the end covers 2 (Fig. 1-4) of the drum 1 (Fig. 1) unloading 9 and loading (not shown in the figure) pipes are installed, as well as fences 10 for protecting electric motors 11 (Fig. 1, 2, 5, 6). Sealing plates 12 (Fig. 1), installed between the sections of the fence 10, protrude beyond the surface of the fence 10 and are blades that create an air flow for cooling the electric motors 11 (Fig. 1, 2, 5, 6). To protect the rim 3 (Fig. 1, 2, 3, 5), a fence 13 (Fig. 1) is installed.

The rim sectors 3 (Fig. 1, 2, 3, 5) are attracted to the outer diameter of the end caps 2 (Fig. 1-4) of the drum 1 (Fig. 1) with the help of ties 14 (Fig. 2, 3) and bolts 15, for which purpose fastening elements 16 (Fig. 3) are made on the rim sectors 3 (Fig. 1, 2, 3, 5), for example, in the form of cylindrical annular projections, and on the end caps 2 (Fig. 1-4) of the drum 1 (Fig. 1) annular bores are made containing a cone, due to which, when tightening the bolts 15 (Fig. 2, 3), the tie 14, which also has a cone, attracts the rim segments 3 (Fig. 1, 2, 3, 5) to the outer diameter of the end caps 2 (Fig. 1-4) of the drum 1 (Fig. 1). The end covers 2 (Fig. 1-4) themselves are made of sectors and are pulled together by wedge ties 17 (Fig. 1, 2, 4) using bolts 18 (Fig. 4), for which purpose grooves 19 (Fig. 4) with inclined walls are made in the wedge ties 17 (Fig. 1, 2, 4), and mating projections 20 (Fig. 4) are made on the walls of the end covers 2 (Fig. 1-4). The joints of the sectors of the rim 3 (Fig. 1, 2, 3, 5) are made at an angle of 5 ... 15 degrees to reduce mill noise and wear of the rim 3.

The support and drive unit 4 (Fig. 1, 2, 5, 6) is made in the form of two plates 21 (Fig. 5, 6), tightened with screws 22 (Fig. 5) and 23 through cylindrical spacers 24 (Fig. 5, 6) and a prismatic spacer 25, respectively. After setting the perpendicularity of the support and drive rollers 26 to the inner surface of the plates 21 due to the relative displacement of the plates 21 and the final tightening of the screws 22 (Fig. 5) and 23, the holes for the pins 27 are finished with a reamer and the pins 27 are pressed into them, fixing the established perpendicularity of the support and drive rollers 26 (Fig. 5, 6) to the inner surface of the plates 21 in the longitudinal direction, maintaining some flexibility in the perpendicular direction, allowing the support and drive rollers 26 to be installed along the rim 3 (Fig. 1, 2, 3, 5). In the axial direction, the support and drive rollers 4 (Fig. 1, 2, 6) are limited by flanges 28 (Fig. 5), secured to the ends of the support and drive rollers 26 (Fig. 5, 6) with screws 29 (Fig. 5) through double-row spherical bearings 30, the movement of the outer rings of which is limited by the bottom of the bores made in the plates 21 (Fig. 5, 6).

Rollers 31 are mounted along the edges of the plates 21, the axis of rotation of which intersects with the axis of rotation of the drum 1 (Fig. 1). Rollers 31 (Fig. 5, 6) are mounted, for example, on two rolling bearings on an axis 32, secured in a housing 33 by a spring ring 34 (Fig. 5). On the housings 33 (Fig. 5, 6) there are hooks 35, which rest against the inner surfaces of the plates 21, ensuring the precise protrusion of the rollers 31 relative to the inner surface of the plates 21 of the support and drive units 4 (Fig. 1, 2, 5, 6), which also determines the maximum possible gap between the rollers 31 (Fig. 5, 6) and the rim 3 (Fig. 1, 2, 3, 5), and therefore the maximum angle of rotation of the support and drive unit 4 (Fig. 1, 2, 5, 6) relative to the rim 3 (Fig. 1, 2, 3, 5).

The assembly of the mill begins with connecting the posts 6 (Fig. 1, 2) together using transverse 7 and longitudinal 8 (Fig. 1) plates with the help of pins and screws (not shown in the figure). Since the coordinates of the hole for the swing bearing in the posts 6 (Fig. 1, 2, 5) are specified from the rear wall and from the top of the post 6, the height position of the posts 6 is set using threaded jacks installed under the bottom plate of the posts 6 and checked using a laser level installed on the upper end of one of the posts 6 and rulers on the upper ends of the remaining posts 6. The verticality of the rear part and side walls of the posts 6 is set using the same jacks and checked using a level. Next, half of end cover 2 (Fig. 1-4) of drum 1 (Fig. 1) is installed on support and drive rollers 26 (Fig. 5, 6), onto which rim sectors 3 (Fig. 1, 2, 3, 5) are pre-installed, except for two sectors serving for additional connection of halves of end cover 2 (Fig. 1-4) of drum 1 (Fig. 1). Drum 1 (Fig. 1) is lowered between halves of end covers 2 (Fig. 1-4) and preliminarily fixed with bolts. After which the second halves of end covers 2 (Fig. 1-4) are lowered and also fixed with drum 1 (Fig. 1) and with each other with wedge ties 17 (Fig. 1, 2, 4). Then the missing two sectors of the rim 3 (Fig. 1, 2, 3, 5) are installed on the sides and secured with ties 14 (Fig. 2, 3) using bolts 15. After the final tightening of the bolts, installation of fences 10 (Fig. 1) and 13 and connection to the electrical network, the mill is ready for operation.

The mill operates as follows. During direct starting of the mill, voltage is supplied to one of the two electric motors 11 (Fig. 1, 2, 5, 6) on each support and drive roller 26 (Fig. 5, 6). Since the starting torque on electric motors with a power of up to 200 kW is more than 2 nominal, the starting torque is sufficient to rotate and accelerate the drum 1 (Fig. 1) almost to the nominal speed. In this case, the starting current from half of the electric motors 11 (Fig. 1, 2, 5, 6) will load the power supply network 2 times less than when starting all electric motors 11 simultaneously and is only 3 times greater than the nominal current. When approaching the nominal rotation speed of drum 1 (Fig. 1), the remaining electric motors 11 (Fig. 1, 2, 5, 6) are started in stages. In this case, the current surge in the power supply network will be insignificant. Direct starting of the mill from a certain position of the drum 1 (Fig. 1), i.e. when the grinding bodies and ore are shifted in the opposite direction of rotation, then direct starting of the mill by also turning on one electric motor 11 (Fig. 1, 2, 5, 6) for each support-drive roller 26 (Fig. 5, 6) and simultaneous disconnection of the electromagnetic brakes of all electric motors 11 (Fig. 1, 2, 5, 6) makes it possible to start the mill when the starting current in the power supply network is exceeded by 1.74 times, which is quite acceptable.

At the initial moment of time, the support and drive units 4 (Fig. 1, 2, 5, 6) are rotated relative to the rim 3 (Fig. 1, 2, 3, 5) by arbitrary angles within the gap between the rim 3 and the rollers 31 (Fig. 5, 6), due to which, when the rim 3 (Fig. 1, 2, 3, 5) rotates, the support and drive rollers 26 (Fig. 5, 6) begin to shift along their axis until they stop through the flange 28 (Fig. 5) and the double-row spherical bearings 30 in the bottom of the bore of the plate 21 (Fig. 5, 6) and through the rollers 31 in the end surface of the rim 3 (Fig. 1, 2, 3, 5). Due to the fact that the support and drive rollers 26 (Fig. 5, 6) are installed in the support and drive unit 4 (Fig. 1, 2, 5, 6) in parallel, they are displaced in one direction until both rollers 31 (Fig. 5, 6) of one of the plates 21 rest against the end surface of the rim 3 (Fig. 1, 2, 3, 5). In this way, the support and drive unit 4 (1, 2, 5, 6) self-adjusts parallel to the end of the rim 3 (Fig. 1, 2, 3, 5).

Ore and water are continuously fed through the loading device, and the mill products exit through the trommel, for example. When the mill is first loaded, the weight of the grinding media, ore, and water is precisely determined, and the deflection values of the levers 5 (Figs. 1, 2, 5) are recorded. Subsequently, any deviations in this value, up or down, are used to determine whether the mill is overloaded or underloaded.

Claims (8)

1. A mill with a friction multi-motor drive, containing racks (6), support and drive units (4), which are double-arm levers made, for example, in the form of two remotely located plates (21), in which a pair of support and drive rollers (26) are mounted essentially symmetrically to the swing axis, driven into rotation by electric motors (11), rims (3) of predominantly cylindrical shape, rigidly connected, for example, to the end covers (2) of the drum (1) and in contact with the support and drive rollers (26), characterized in that rollers (31) are mounted predominantly along the edges of the plates (21) with the possibility of contact with the ends of the rim (3). 2. The mill according to claim 1, characterized in that the rim (3) is made in the form of sectors with fastening elements (16) to the end covers (2) of the drum (1), for example, with the help of two ties (14) having a conical section in contact with an annular conical section made on the end covers (2) of the drum (1), tightened with bolts (15). 3. The mill according to item 2, characterized in that the joint of the rim sectors (3) is made at an angle of 5...15 degrees to the axis of the rim (3). 4. The mill according to item 2, characterized in that the rollers (31) are mounted on rolling bearings in the housing (33), rigidly connected to the plate (21) of the support-drive unit (4), and the hook (35), made on the housing (33), contacts the surface of the plate (21) from the side of the rim (3). 5. The mill according to paragraphs 1 and 4, characterized in that the difference in the protrusion of the rollers (31) beyond the surface of the plate (21) on the side of the rim (3) is no more than 0.3 mm, and the distance between the rollers (31) and the rim (3) is 0.5...3 mm. 6. The mill according to item 2, characterized in that the joints between the sectors of the rim (3) are 0.5...2 mm. 7. The mill according to item 1, characterized in that, predominantly in the center of the rim sector (3), a hole is made for a pin connected to the end cover (2) of the drum (1). 8. The mill according to item 1, characterized in that the end cover (2) of the drum (1) is made of sectors connected to each other mainly by wedge ties (17).