A new groove sleeve developed by Dura-Belt, of Ohio, USA, relies on Stevens Urethane thermoplastic polyurethane (TPU) for traction and performance to increase the load-bearing capacity of industrial conveyors. The sleeve, a flat loop made from Stevens Urethane, slips into the drive-belt groove on conveyor rollers. The TPU provides a high coefficient of friction (COF) between the steel roller and the drive-belt, reducing slippage of the belt under heavy loads and increasing conveyor weight capacity by up to 50%.
'Round drive belts tend to slip as they reach maximum load capacity,' says Jim Hammond, president of Dura-Belt.
'Our new groove sleeve is a quick, simple way to improve performance and extend the weight range, without having to redesign the conveyor system.' Conveyors typically comprise a series of motorised rollers using a system of belts to drive non-powered slave rollers.
Conveyor load is limited by, among other things, the amount of power the motors can transfer before the round drive-belts begin to slip on the metal rollers.
Dura-Belt's new groove sleeves compress around the drive-belt as it turns, forming up the sides of the groove and around the belt.
This increases the contact surface area between the belt and the roller and provides a higher coefficient of friction for better traction under heavier loads.
Tests prove that the new sleeves prevent slippage in applications where slip is a problem and increase load capacity by as much as 50%.
Conveyor performance has improved even in tough end-use environments, such as post offices and courier terminals where paper dust can infiltrate equipment and reduce COF.
Hammond notes that while there are other options for a groove sleeve design, such as spraying a substance on the roller and baking it, they tend to be expensive, difficult, and time-consuming.
'The TPU sleeves just slip right on over the roller ends, and you're done,' he says.
Dura-Belt is currently using a flat sheet of Stevens SS-1485 material, 0.76 mm (.030') thick and cut into strips 9.52 mm (3/8') or 6.35 mm (1/4') wide, then hand-welded into the closed-loop groove sleeve.
As production needs increase, the company plans to investigate an alternative extruded tube method, which would simply be sliced to the required width.
'We chose TPU because it is strong, tough and durable, with a very long working life,' Hammond says.
'It also stretches easily over the end of the roller, a 50-75% stretch, and bounces right back to its original length with no loss of tolerance.' Stevens SS-1485 is a versatile, general-purpose polyester TPU.
It has excellent mechanical properties and exhibits good resistance to oils and solvents.
Stevens Urethane provides Dura-Belt with a mirror-smooth finish on both sides of the material, providing maximum surface contact with both roller and belt for optimum grip and strength.
Stevens Urethane film and sheet is manufactured in thicknesses from 0.025mm to 3.2mm (.001'-.125') and in widths from 12.7cm to 203cm (5'-80').
Tensile strength up to 10,000 psi assures reliability and durability over a long working life, and urethane film and sheet can elongate significantly and still return to its original dimension with no loss of 'memory'.
Stevens Urethane is available in hardnesses from 75 to 95 Shore A, and in a range of standard and custom colours.
Various opacities and surface textures are also available.
Based in Holyoke, Mass., Stevens Urethane manufactures a full range of high-performance urethanes for use in a wide variety of 'can't fail' applications for consumer, medical, commercial and industrial markets.
Stevens Urethane is the only company in the world to offer urethane in blown film, extruded sheet, tubing, cord, and profile form.