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Increase cutting table output through linear drive optimization

What if your machine is confronted with the technical limits of acceleration and deceleration? Apex Dynamics recently advised a major manufacturer of Laser cutting tables on optimizing their linear drive. An adapted use of low-backlash gearboxes, pinions and racks ensured a higher effective output and prevent overloading, tripping controllers and excessive wear. We discuss the consideration and benefits of each component and how this ultimately led to a better-performing machine with a lower cost.

The cutting tables are used for processing wood, steel, aluminum, leather, textile and plastic sheets. The machine was after years of development and optimization against the technical limitations of the design and so it was time for an redesign. The entire construction of the Laser cutting table has been revised; as many lightweight materials as possible were used and great care was taken in the selection of components.

With this modified design, the performance is improved (higher output), repeat accuracy is increased (smaller dimensional tolerances for the end product), the delivery time is shortened and the cost of the machine has been reduced (optimized system delivery). The machine has been running for a while in a pilot setup and is performing beyond expectations. The following components have been chosen:

Low-backlash gearbox with low no-load torque

Due to the low no-load torque and the high efficiency, the power loss is minimized. Due to low inertia, the control can be quite dynamic without the motor being overloaded. The no load torque of the gearbox is so low for the following reasons:

• At the input side of the gearbox, the ball bearing and the seal are separated from each other. This allows the input bearing to revolve IN to the planet carrier, where it rotates at a RELATIVE speed. (the input speed -/- the output speed of the first stage)
• The sealing can therefore take place at the smallest possible diameter, i.e. with the frictional force at the smallest possible diameter.
• In addition, the seal runs on a hardened and ground ring for extra low friction. (hardness 3700HV and an Ra of 0.2μm!)

The gearbox naturally has a low backlash and high rigidity for perfect reproducibility.

Quality 4 pinion (Curvic-plate)

Thanks to the Curvic-plate pinion (quality 4) it was possible to choose the optimum number of teeth and therefore the diameter. With a number of teeth above 20, the rotational play will lead to a larger linear backlash of the system. With a number of teeth below 20, the wear increases over time. Empirically, a tooth count of around 20 is optimal.

Moreover, the pinion with the curvic plate has a very high rigidity.

Rack, quality class 6

Toothed racks of quality class 6 with hardened and post-ground teeth ensure an ideal interaction with the pinion. The toothed racks have a length of up to 2 meters, so that the number of seams can be limited and time can be saved in the assembly. Due to tooth-for-tooth hardening, the accuracy is high, the feeding force approximately 20% more than the toothed racks used so far and the tooth base has remained tough, so that the risk of damage in the event of a calamity is limited.

In addition, all Apex Dynamics racks are first magnetized (checking for cracks) and then demagnetized at 10 +/- 3 Gauss (1 Gauss = 10^-4 Tesla). This has advantages if magnetic materials are processed: they are not so strongly attracted by demagnetization and the risk of damage is thus further reduced.

Lubrication installation

A complete lubrication system (optional) is able to lubricate the entire installation fully automatically for more than 5 years (!). The system consists of a lubrication cartridge, automatic pump, distributors, pre-filled hose and support shafts for precise lubrication of the pinion and can be adjusted as required. A possible fault is automatically displayed on the screen of the PLC so that expensive damage is excluded. See an animation of our full automatic lubrications system below.

In this collaboration, it is clear what advantage can be achieved if you work together with a specialist in the field of linear drive. Would you also like to have your drive examined or redesigned?
You can contact Apex Dynamics for the best advice,