Drum (component)
The drum is a component of conveyor technology , especially belt conveyor technology . Drums are mainly the components with which an endlessly circulating conveyor belt is driven, deflected, or deflected horizontally. In contrast to the conveyor roller , which only serves to support the belt in the upper and lower run of a belt conveyor system and guides and holds the belt at one level, the drums of a belt conveyor system also absorb the longitudinal tension that is required to operate this system.
A distinction is therefore made:
- Drive pulley - introduction of the drive energy from motors via gears into the drum and via frictional engagement in the belt, deflection of the belt from the upper run (conveyor run) into the lower run;
- Reverse or simply sweeping drum - deflection (reversal) of the belt from the lower run to the upper run (conveyor run);
- Kink or deflection drum - deflection of the belt to another height level.
A drum basically consists of at least three components:
- Drum shell;
- Drum bases with options for receiving or mounting the shaft or axis;
- Drum shaft or axle.
Drums are manufactured in "external storage" or "internal storage" depending on the operational requirements.
Drive drums are always externally supported, i. H. with a drive shaft, usually fixed by tensioning sets, which is supposed to introduce the desired drive torque from the drive unit motor / gearbox via the drum as drive force into the belt. The roller bearings are located outside the drum on both sides of the shaft and are each built into a plummer block housing that is attached to the conveyor system. In order to compensate for linear expansion as a result of different operating temperatures, these bearings are always designed as a pair of fixed and floating bearings.
All other drum types, such as the reverse and buckling drums, are used in both versions with "internal storage" or "external storage". The spatial conditions and the local access options at the installation sites are decisive here. Externally mounted drums with their external roller bearings and bearing housings require more space than internally mounted drums because of their approx. 400–600 mm larger overall width, where only a short axle end protrudes over the drum width on the right and left. The advantage of externally mounted drums is u. a. in that if a bearing fails, the drum can be kept in operation immediately after the defective bearing has been replaced. In the case of internally mounted drums, if just one bearing fails, the entire drum must be replaced with another for repair. This means that in order to provide for constant conveyance in the event of a rolling bearing failure, only a spare bearing has to be kept available for an externally mounted drum, but a completely new drum has to be kept as a reserve for internally mounted drums to keep the downtime as short as possible to keep.
The design of the drums depends on the operational requirements. The drum length results from the required belt width, which should be designed for a sufficiently large conveying capacity. The drum diameter depends on the locally available belt tension and the type of belt. Because of its relatively large bending radius, a steel cord belt requires a drum with a larger diameter than a textile belt. The dimensioning of the drum diameter is described in DIN 22101 (continuous conveyor - belt conveyor for bulk goods - principles for calculation and design), the subject of drum types and their possible designs is discussed, among other things. a. dealt with in VDI 3622 (belt conveyor for bulk goods - belt drums).
The choice of materials and their dimensioning is determined by the loads from the resulting belt tension.
Drive drums are generally coated to improve the frictional connection between the drum and the belt and because of increased wear protection; the coating material is rubber or ceramic.
Reversing drums, as well as buckling or deflecting drums, are also coated on belt conveyors that tend to get dirty. The material is usually rubber. The coating is applied to the drum shell in a diamond shape because of its better resistance to dirt.