Robot tool tested on space-frame

The Tricept machine, launched by Comau seven years ago, is being used by Warwick University in a study of car part machining. Dr Ken Young, principal research fellow at the Warwick Manufacturing Group, believes Tricept could be an alternative to conventional five-axis machining, where cost is more critical than accuracy. He took delivery of a […]

The Tricept machine, launched by Comau seven years ago, is being used by Warwick University in a study of car part machining.

Dr Ken Young, principal research fellow at the Warwick Manufacturing Group, believes Tricept could be an alternative to conventional five-axis machining, where cost is more critical than accuracy.

He took delivery of a Tricept in April, using a £130,000 government grant which also covers a flexible tooling system.

The Tricept is described as a robot, but it behaves like a flexible machine tool. It will be used to evaluate the machining of unwieldy aluminium fabrications being adopted by the car industry as it moves towards space-frame vehicle construction that exploits lightness and strength.

Young, who first saw the Tricept at work on a Volvo cylinder head line, says the fact that all the machine movement is with the tool and not the large workpiece helps explain why the Tricept is cheaper than conventional machining, while the robot controller makes it easy to integrate it in a transfer line.

Despite this, the market has been reluctant to adopt Tricept, perhaps because of the blur between parts handling and precision metal cutting.

The Tricept has six degrees of freedom within a nominal volume of 2,000mm in the X axis, 1,500mm in Y and 600mm in Z. It has a linear speed of 0.5m/sec over the 600mm stroke and a rotational speed in the wrist movement of 270 /sec.

The wrist carries a high speed 30,000 rpm spindle from Swiss maker IBAG.

In a test to prove the robot is as fast as a three-axis machining centre, it took two and a half hours to mill the full-size complex resin form of half of a ship’s bell holder.

Laser and water-jet cutting are potential applications for the Tricept, which can produce forces of up to 1.5 tonnes. Press-fit assembly is another.

Three linear actuators arranged around a rigid centre tube give the design inherent structural stiffness.