The 850-style rolling motor has become a staple across many industries for tube rolling. This push pull style motor exhibits both quality and performance, making it ideal for expanding tubes in chillers and heat exchangers.
Alfa Laval ACE, located in Broken Arrow, OK, specializes in heat transfer, separation, and fluid handling technology. With a focus on producing quality air coolers for their customers, rolling consistency was of utmost importance. With their current tube rolling method relying heavily on operator feel to regulate the amount of wall reduction, the accuracy of wall reduction was lower than desired. This resulted in too much time spent re-rolling tubes.
With a wide variety of rolling motors on the market, choosing the right one can seem overwhelming. There are several factors to consider when selecting a rolling motor. Power source, torque control, RPM, torque range, and the style of the motor will vary depending on the application.
The quality of an air motor will be determined based on manufacturing processes, design, and maintenance. In order to improve cleaning performance and tool life, it is important that the motor is designed for use in a specific application. This assures optimum performance and extended life of the motor.
Contractors and maintenance personnel agree, the current method of tube cleaning using a rotary flexible cable to clean chillers is a hassle. The cable is problematic; it breaks, the feeding mechanism jams, and the feeder needs frequent and costly repairs. Substantial downtime is encountered to repair cables and units.
There are two motor power sources that are used for expanding tubes mechanically: electric rolling motors and pneumatic rolling motors. Determining what motor to use for a job will depend on operator preference, availability of electricity or air, and the application.
Expanding tubes after they have been welded can be frustrating for operators. If not rolled properly, tube material can build up and put stress on the weld. In extreme cases the tube material can build up so much that the expander can get stuck in the tube, delaying the job.
Tube Expanding is based on engineering principles, involving elasticity and plasticity, to compress the OD of the tube against a fixed container, such as rolling tubes into tube sheets, drums, ferrules or flanges. To assure a proper tube joint, the tube wall must be reduced by a predetermined percentage. The following chart can be used for determining the correct tube wall reduction.
Before you can start rolling, you will need to select the right expander for the job. Tube OD, and Wall/BWG will determine the size of the expander. However, there are some other factors to consider, such as tube projection, roll length, reach requirements, space constraints, and whether it’s minimum or average wall tubing.
Firetube boiler tubes consist of an expanded and beaded tube end. The method for achieving a bead has advanced over the years to include both hand beading and single roll beading expanders. In order to ensure a proper bead, there are several steps that need to take place before expansion can occur.
