Tracking the Material Efficiently
How a track drive system can provide several benefits to a tube fabrication process.
Fabricators all over the world build parts in lots of all sizes. Ranging from quantity of one to pick a number, most process demand a precision feed system. However, when it comes to feeding a straight tube length into a machine, a quality part is always expected to emerge on the far side of any process. This is true even if you are prototyping a small quantity of parts.
Consistency is the name of the game. And this holds true for cutting tubing, bending tubing, or even laser cutting.
Historically cut to length machines have made use of various devices used to advance the tube into the cutting zone. For example, powered roll drives, hitch feed type devices, and feed mechanisms that push on the end of a tube are all on the market today. All these devices have their pros and cons. Nevertheless, a track drive system, under certain conditions, has its advantages as well.
A track drive system most often makes use of 2 timing belts; see Figure 1. The timing belts are forced towards one another. When a tube is placed between the belts, the tube is held firmly between the belts under a compressive load. Driving one or more of the pulleys will cause the belts to pull/push the tube in a linear fashion. Typical drive systems can include a servo or stepper type motor.
Figure 1 above shows a CAD model of a track drive system making use of (2) timing belts. When forced together, the two timing belts make for a good means to transfer a tube linearly.
A few advantages of this approach pop right out. First, as the tube diameter changes, the belts can compensate for this. This means that going from an Ø1/4” tube to an Ø1/2” tube involves no tooling changes. This is not the case with a roll drive or a hitch feed device when it comes to feeding the part.
Depending on the control system used, the roll drive approach may vary the linear displacement of a round tube depending on how the tube fits in the grooves of the roll dies. If the tube diameter is a little undersize, the linear displacement of a round tube may be less than expected. This is not the case with a track drive system. Advancing the track drive with a tube firmly gripped between the belts produces a 1:1 displacement. This is required when a fast trapezoidal servo move is needed.
From Figure 2 below a servo system is used to advance an Ø1/8” copper tube into a precision saw operation. The track drive is most efficient moving the tube thru the process. A dead-man switch, located to the left of the track drive, determines when the system is low on material.
Figure 2 above shows a track drive system used to advance a small diameter copper tube in a sawing operation.
Within reason, a track drive system can transport tubes as small as Ø1/32”. On the high side you are limited by the selection of timing belts available. Some of the applications employing this type of drive system involves cut to length lines (saw cut, abrasive cut, chip-less cut, etc.), automatic tube bending machines, and certain equipment making use of lasers and laser marking devices. In general, any tube fabrication application may be able to make use of this feeding approach.
George Winton, P.E. designs and builds CNC tube fabrication equipment for Winton Machine in Suwanee, GA. He can be reached at [email protected] or 888.321.1499.
About the Machines We Build
All of our semi-rigid coax and tube fabrication machines at Winton are designed, manufactured, and tested in-house. We have a large line of standard products as well as the ability to engineer the best solution for our customer’s needs. Our experienced sales staff makes sure that our customers can justify their capital equipment investment by offering a solution that is exactly what they need in order to manufacture their parts. Please contact us today to discuss your project.