Novel new tool head design for cutting machinery slashes the cost of migrating to 3D movement

Citation

(2010), "Novel new tool head design for cutting machinery slashes the cost of migrating to 3D movement", Assembly Automation, Vol. 30 No. 1. https://doi.org/10.1108/aa.2010.03330aaf.002

Novel new tool head design for cutting machinery slashes the cost of migrating to 3D movement

Article Type: Mini features From: Assembly Automation, Volume 30, Issue 1

Eliminates weight, cost and system integration issues for plasma, waterjet and laser cutters.

CNC vendor NUM has launched an innovative ready-integrated pan-and-tilt tool head solution for sophisticated plasma, laser and waterjet cutting machinery applications. Called NUMcut, it provides a very simple means of extending the capability of machinery from 2D to 3D applications, with precise multi-axis interpolation (Figure 2).

Figure 2 The NUMcut tool head

The package includes a new tool head design that brings many technical advantages to the cutting machinery sector. A novel mechanical design provides the versatility of movement and stiffness required to implement precision cutting motion, but with the unique advantages of very low mass, and the elimination of cabling runs that need to flex with the tool head movement. Owing to its unusually low weight, the new head offers a very simple upgrade path for CNC machines in the cutting machinery market.

The NUMcut tool head employs gimbals and the Cardan universal joint to convert the movement of two linear actuators into 360° of panning motion plus control of tilt angle up to 47°. Combined with the conventional three-axis X-Y-Z movement of the underlying cutting machine, NUMcut offers machine builders a simple means of migrating machinery to sophisticated three-dimensional performance. A simpler and smaller version of the tool head offering control of tilt angle up to 8° is also being made available, to allow machine builders to compensate for the taper of plasma or waterjet beams. This variant is considerably smaller, allowing multiple tools to be mounted if required.

The Cardan-based mechanics give the toolhead a number of substantial technical advantages compared with current alternative motion control approaches – which include solutions such as motion control systems with motors and gears mounted on the moving head, or complex mechanical arrangements such as parallelogram frames.

In NUM's design arrangement, the tool holder sits inside dual gimbals, which are mounted on a fixed yoke frame. This means that the actuating elements – two rods with Cardan joints driven by linear actuators – are very small and light. As a result NUMcut weighs only 30 kg. This is as little as a third that of some 3D toolhead structures used on the machinery market today – saving a great deal in terms of motor and drive costs, physical size, and energy consumption.

The yoke element of the design means that stiffness is not compromised, virtually eliminating backlash. The movement characteristics of NUMcut also mean that only the cutting tool itself is subject to the panning and tilting movement, thereby avoiding any need for cable runs to motors, encoders, etc. that are then forced to flex and twist with the tool head's motion – adversely impacting equipment reliability.

NUMcut is offered as a complete turnkey solution for machine builders, for either 2.5 – or 3D tool head control: each version of the tool head is supplied with all the supporting hardware and software required: servomotors and drives, and the Flexium CNC kernel including the drivers that transform 3D path tracing motion into interpolated motion control commands for the two linear axes. The package allows simple programming in the typical style of a five-axis machine – with three linear and two rotational axes of movement. As the tilt angle is limited by mechanics to a maximum of 47° in all directions, operator safety is assured and any need for additional protection measures are minimised.

The tool head's low weight and compact form factor makes it easy for a machine builder to convert an existing simple three-axis cutter into a five-axis machine. Alternatively, it becomes simple to design one new machine platform that can be assembled in three- or five-axis variants.

A video illustrating the principle of NUMcut's motion is available at: www.num.com/numcut

For further information, please contact: NUM (UK) Ltd, Unit 3 Fairfield Court, Seven Stars Industrial Estate, Wheler Road, Coventry CV3 4LJ, UK. Tel.:+44 871 750 4020, e-mail: sales.uk@num.com, web site: www.num.com