TPT March 2018

T E CHNOLOG Y

Designing efficient drive trains HOW does a mill builder size a drive train to its customer’s needs? Depending on whether it is for the roll forming or tube mill markets, different results are desirable. For roll forming machines Formtek generally sizes the drive train for the maximum product (strip width and wall thickness) at the maximum line speed (generally 100 fpm). the torque begins to drop off. Thus, if the roll former needs to go faster, it could do so but only on lighter gauge products. Typically, this is not necessary because there are many other limiting factors on the roll forming system that will limit speed.

will pull less torque that matches the natural drop of the motor once it surpasses the designated base speed. Mostmotors aredesignedaroundbase speeds of 850, 1,150 and 1,750 rpm. The top speeds are normally between 2,000 and 2,500 rpm. Thus, motors that hit full horsepower at lower rpm will provide much higher torque than a motor that will hit full horsepower at higher rpm. The difficult task is developing the equations that will correctly model the loads and yield the required horsepower and torque. Formtek has developed these equations through years of experience, experimentation and theoretical calculations, which helps it to handle all manner of challenging customer applications.

This scenario is not so easy with tube mill systems. Various products, various yield strengths of materials and various speeds all factor into the drive train design and motor efficiency utilisation. However, the same scenario plays out – it is desirable to gear the mill into the largest horsepower draw. That is typically the largest OD, heaviest wall thickness and highest yield strength. If the customer gears the mill so that the horsepower curve meets full potential at the base speed (where the most torque is needed) on the largest product, you will be in a favourable position to allow lighter products to go faster. Consequently, the lighter products

Formtek will size the total mill horsepower so the maximum product size will utilise 100 per cent load from the motor at the motor’s base speed. Base speed for a motor (AC or DC) is defined when the motor reaches maximum horsepower and maximum torque at the same time. For the roll forming market this is usually the best method and most common practice. Technically, the roll forming machines can go faster when the motor is taken past base speed (commonly known as overspeeding). An interesting thing happens once this action is performed: the horsepower stays constant while

Formtek, Inc – USA Fax: +1 216 292 2898

Email: yoder@formtekgroup.com Website: www.formtekgroup.com

ISO-9001:2008 certified company

A RANGE OF PRIMACY

CUTTING EXPERTS

STARK S.p.A. Italy Phone +39 0432 998811 E-mail: info@starktools.com http://www.starktools.com

Stark India Toolings (PVT) Ltd. India Phone: +91 (0) 22 40661234 E-Mail: total_tools@yahoo.co.in Stark Tools (Suzhou) CO., LTD. P.R.China Phone +86 (0) 512 58907826/28 E-Mail: stark@starktools-cn.com Stark Do Brasil Ltda . Brasil Pabx +55 (0) 11 2721 6965 E-Mail: starkbr@starkbr.com.br Phone +49 (0) 7361-55647-0 E-Mail: post@starktools.de Vertriebsgesellschaft STARK GmbH & Co. Germany

Market leader in HSS and TCT circular saw blades for tube cutting. TAKE THE CHANCE TO INCREASE YOUR PRODUCTIVITY! MADE IN ITALY

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MARCH 2018