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More than just Pick&Place: production and assembly with HIWIN robots

ThermProTEC manufactures equipment for the production of more lightweight tubular stabilisers for a leading German automotive supplier. The key task of each piece of this highly automated equipment is not only to thermally treat the pre-bent tubing blank, but also to glue on the rubber bearings and assure quality. Robots from HIWIN ensure the flexibility required at central points during the production of these sophisticated suspension components.

Stabilisers play an important role in a vehicle’s suspension system, as they prevent the vehicle from swaying on a bend or uneven road surface. They therefore contribute significantly to the comfort of modern vehicles. In the past, these stabilisers were exclusively formed from all-metal bars in a cold or hot process. What are referred to as tubular stabilisers are now becoming more and more popular due to the fact that they weigh up to 40 per cent less. 

However, tubular stabilisers call for entirely different thermal production methods compared to all-metal stabilisers. ThermProTEC, a specialist in thermal process technologies, has developed the ideal method for this and has successfully broken into the market with it.

“Our in-depth understanding of thermal processes opens the door for us, even to companies that are much bigger than ourselves,” explains Dr. Rainer Gaus, founder and Chief Executive Officer of ThermProTEC GmbH based in Offenburg. “Here, like in other markets in which we are active, such as tempering equipment for heavy mining chains or gear racks, clients are increasingly requesting that, alongside the actual thermal treatment, we cover as many of the production steps required in the respective application as possible with our equipment.”

This entails end-to-end automation including necessary measurements for quality assurance as well as the handling of workpieces.

In this context, ThermProTEC has been increasingly implementing robots in its equipment for some years now in order to feed or withdraw heavy components. When it comes to the stabiliser production equipment, numerous robots also come into play. Robots from HIWIN have been involved in this from the very start. 

A robot instead of a gantry system

“We have a large number of HIWIN linear guideways installed in our equipment and have experienced very positive results with them over the years,” says Gaus. “I therefore followed HIWIN’s plans to develop its own robots with a great deal of interest and ordered three of the RA605-710-SL model for test purposes as soon as these were available. I already had our stabiliser production equipment in mind as a potential area of application.” 

Once the compact 6-axis robots had been successfully tested, the design engineers at ThermProTEC suggested using a robot with a 5 kg load capacity in a Pick&Place application conventionally solved with a gantry system. By means of a dual gripper, the robot picks up a clamp and a counter-piece from an infeed belt and places them in the two receptacles of a pressing station. The station then presses the clamp pieces onto a rubber bearing previously glued on by the equipment. 

Flexibility cuts costs in terms of construction and tools 

Thanks to the flexibility of the robot, the equipment can process different clamp designs without any problems, which isn’t the case with a gantry system. A 2D smart camera of the Inspector PIM 60 model detects the type and orientation of the clamp fed in by a conveyer belt and forwards this information in XML format to the HIWIN robot control system via Profinet. The robot learns the different gripping positions depending on the clamp type via teach-in. 

“Despite the higher entry price compared to a gantry system, the customer opted for the robot solution as a result of its flexibility,” reveals Gaus. “In the long term though, robots are less expensive for us, especially if the production of variants is to be possible or product changes are to be expected.” Whereas, for example, an extra tool has to be produced for every new product when using a gantry system, usually only a few standard grippers are enough to handle a whole product portfolio when using a robot. What’s more, the construction effort is generally lower with a robot solution in contrast to conventionally arranged Pick&Place systems because the latter have to be individually adapted to the equipment and task each time. ThermProTEC also chose not to have the clamps taken directly out of a provided crate by the robot. “Depending on its implementation, this concept would have required at least one 3D camera or an additional sensor and would have therefore simply not been worth it. We decided to place the clamp on the infeed belt using a magnet. That is much more cost-effective and reliable,” according to the CEO of ThermProTEC.

All-in-one control system

HIWIN robots also offer users added investment security and plannable costs. When users purchase the modular RCA605 robot control system developed in collaboration with KEBA, they get access not only to comprehensive hardware comprising an integrated safety controller, a configurable real-time Ethernet interface, a sequence controller (PLC) and extendable I/Os, but also to wide-ranging function libraries.
As a result, functions for palletisation or conveyer belt tracking, for example, do not have to be licensed or paid for separately. They can be used without additional costs when upgrading or converting equipment. A scope analysis software program is also supplied as standard for optimising movement sequences.
Programming is carried out in a consistent engineering environment for PLC, motion and robotics. 

Wide range of applications through high repeat accuracy

The robot proved its worth in the first piece of delivered equipment, leading ThermProTEC to expand the area of application of HIWIN robots. In the second piece of equipment realised by the company and delivered at the end of 2018, two of these little helpers place clamps in a pressing station. Another RA605-710-SL additionally works in a measuring cell. In this application too, the robot cooperates with a 2D smart camera of the Inspector PIM 60 model. However, this time the camera is mounted on the flange of the robot. A distance sensor is also located here. The trio allows the stabiliser to be measured in 3D at nine positions within 15 seconds.

The RA605-710-SL has the best prerequisites, even for tasks of this kind: Alongside the simple handling of small parts, its high repeat accuracy of +/-0.02 mm also makes it suitable for applications such as assembly, deburring and polishing or even for quality assurance, as Gaus confirms: “Owing to the high repeat accuracy, we were able to achieve absolute overall measuring accuracy of 0.05 mm with the measuring cell.”

Outlook: more HIWIN robots 

In light of all this, the HIWIN robot has performed impressively in this application too, and the CEO is therefore already considering other ways in which it could be used, such as for placing rubber blanks in mould cavities, which has been carried out manually up to now. “We have to take each day and each application as it comes though and weigh up whether a robot solution ultimately makes economic sense. But in general, we will certainly be installing even more HIWIN robots in our equipment in future,” proclaims Gaus with optimism.