Conveyor components HM150 formed rollers

Conveyor technology current situation

The bulk materials industry continuously strives for in-creased output and increasingly reliable conveyor sys- tems. Suppliers have responded with a broad range of rollers for regular or heavy-duty use. No doubt, we have refined these products with incremental improvements.

Sandvik is committed to its full range of high quality tra-ditional rollers. We have also identified the need to inno-vate, to provide additional value to our customers and to do more than simply meet specifications and delivery.

NEEDED ROLLER IMPROVEMENTSRollers fail – it is part of life when you operate or service a conveyor system. And if the mean-time-to-failure trans-lates into regular headaches, the traditional answer is to make rollers heavier and stronger. Wear life is improved with thicker shells; larger bearings are used; and the solid shafts are also made heavier. These efforts can then be counteracted by poor balancing or alignment which may still put unsustainable loads on the bearings.

The costs go beyond purchase price as there is the effect of higher en-ergy consumption as well as the additional demands on the pulleys and drives. Then we consider the human aspect. There is an increased risk from lifting heavy rollers in not-so-easy-to-reach places as well as the environmental impact from increased conveyor noise affecting workers and the surroundings.

HIGH SPEED LIMITATIONSIn applications such as lignite mining or iron ore processing, speeds up to 11 meters/second (36 feet/sec) and capacities up to 52,000 tonnes/hour are common. For such speeds, traditionally welded heavy-duty rol-lers must be machined for roundness. To compensate for the metal loss, the rollers are dynamically balanced and counterweights are applied – complicated indeed.

SANDVIK INTRODUCES TECHNOLOGY SHIFTFor traditional rollers, a series of simple manufacturing steps result in a complex product. With the new HM150 formed rollers, an intelligent design and sophisticated manufacturing process gives a more straightfor-ward product – with superior characteristics. Great ideas are always simple and provide the greatest value, in this case advancing your conveyors’ performance.

TRADITIONAL ROLLER

Tube

Bearing supports machined from solid

Solid through-shaft

Multiple labyrinth sealing system

1

2

3

4

Labyrinthabdichtung

Formed shell

Formed bearing seats

Formed shaft

Formed rollers advancing conveyor performance

Formed roller refers to both the manufacturing process and the end result. Through steps of both cold and hot forming the tubular material becomes a roller with integral bearing seats. Extensive research by Sandvik optimized the shapes, material properties and perfected the process. Using precision machinery and tooling, formed rollers are produced with greater consistency and results than ever achieved before.

LONG LIFEThe forming process increases the steel wall thickness by 50% for a length of 100 mm at the center of the roller where the physical loads are the greatest. 1 The rest of the tube wall thick-ness is reduced by approximately 20% which removes unnecessary material to provide weight reductions. The thicker wall, in combination with a smooth surface finish and fine-grained, work hardened steel, lead to dramatically increased shell wear life at the high wear areas of the roller.

With the bearing seats 2 formed as integral part of the shell, the opposing bearings are tightly aligned. Thanks to the increased steel thickness in both the middle of the shell and the seats, deflections are minimized under load. With an excellent surface finish of 0,5 µm (0.02 mil), frictional corrosion is avoided.

A high quality labyrinth seal 3 effectively keeps the bearing grease in place. The combined result – a much extended bearing life.

QUIET ENVIRONMENTFormed rollers are naturally balanced. This is most critical at high speeds, but is beneficial in any conveyor system. Measurements have con-firmed noise reductions up to 20 dBA compared with other heavy-duty rollers. Even compared with dynamically balanced rollers, a reduction of 10 dBA has been documented. That means a significantly reduced noise for workers and the surroundings.

EASY HANDLINGCompared with other heavy-duty rollers, total weight is reduced by between 10 and 30%. For maintenance personnel, that can make a huge difference. Install rollers quickly with less risk exposure.

ENERGY SAVINGSIn formed rollers, a large diameter tubular shaft 4 can be used. In the process, the diameter is decreased at the bearing ends and the wall thickness increased. The overall impact is an optimum strength-to-weight ratio. In addition the graduated shell thickness provides a reduced rolling mass. With less dead weight and smooth turning, the power consumption is lowered by up to 3 Watts per roller – reduced operating cost.

INCREASED CAPACITYShort of major expansions, the most effective ways to boost conveying capacity are to reduce down-time and increase belt speeds. Sandvik’s HM150 formed rollers let you do both within existing infrastructure. Increased roller life, reli-ability and energy efficiency create new oppor-tunities for raised tonnage conveyed per hour.

FORMED ROLLER

Traditional roller

Formed roller

Hands-off performance under pressure

Bearings – all too often the weak link in any roller – perform best when installed with the optimum contact pressure. With formed rollers, Finite Element Analysis confirms an averaged 25% reduced surface pressure on the inner bearing ring than on traditional rollers, for an advantage right out of the box.

Under a loaded conveyor belt, the formed roller deforms on an average of 30% less. Inside the bearing this lower deflection translates into substantially less misalignment of the bearing rings. These calculations therefore support why formed rollers turn with less power and higher reliability.

But it is not all about theory. Field experience confirms the performance advantage. One lignite mine was experiencing a roller life in an extremely arduous application of about 3 months. A trial of 500 Sandvik HM150 formed rollers showed each and every roller was still in operation after 18 months.

HM150 formed roller product assortment

Sandvik HM150 formed rollers are suitable for the high belt speeds and tonnages required in lignite mining, iron ore processing and other demanding conveyor applications. Formed rollers are available within these specified parameters.

Roller length 380 - 1450mm (15 - 57 inches)

Shaft diameter mm/inch

Bearing size Shell diametermm/inch

Bearing seats mm/inch

51/1.97 6308 159.0/6.26 178.0/7.01 194.0/7.60

40/1.57

63,5/2.5 6310 159.0/6.26 178.0/7.01 194.0/7.60 219.0/8.62

50/1.97

82,5/3.25 6312* 194.0/7.60* 219.0/8.62

60/2.36

*special request

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SANDVIK MINING AND CONSTRUCTION • www.sandvik .com

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