Robot handling system for printed circuit boards

Profile

• What was needed: multidimensional moving energy supply system triflex® R, which was supplied as a ready-to-install readychain® -energy chain system
• Requirements: energy chain must be able to keep up with the high traversing speeds and acceleration and be extremely flexible, as the robot's movement sequences can be freely programmed; every cubic centimetre counts, so the solution must be compact; the highest demands are placed on cleanliness (cleanroom solution)
• Industry: Photovoltaic and printed circuit board production
• Success for the customer: energy supply adapts optimally to all movements; small bend radius allows particularly compact installation; material has the necessary classifications for cleanroom technology; economic advantage: instead of six, all cables now run in just one energy chain

Problem
The Schmid Group, headquartered in Freudenstadt, specialises in the development and manufacture of systems for photovoltaic and PCB production. The competence centre for handling technology is located at Schmid Technology Systems in Niedereschach. The product programme of this subsidiary includes loading and unloading systems. These systems separate PCBs, for example, which are arranged on cassettes, and feed them to a processing station via a conveyor belt.
The ever-increasing processing speeds and customer demands for greater flexibility have led to the development of a whole new generation of handling systems. While linear units were previously used to move the individual axes, a six-axis robot is now being used for the first time, which can load and unload cassettes with PCBs with cycle times of less than seven seconds. However, the flexibility of the system is more important than its speed. Because the robot can be freely programmed, a wide variety of movement patterns are possible - without any modifications or interventions in the hardware. For example, cassettes can be loaded and unloaded at different angles of inclination. The system is completely enclosed because PCB handling places the highest demands on cleanliness. Compactness therefore plays a major role - in cleanroom technology, cubic centimetres are the norm.
An interesting detail of the system is the gripper, which automatically recognises the size of the respective circuit board. The carrier plate with the vacuum grippers is made of weight-saving carbon fibres so that a compact 16 kg robot can be used and handling goods weighing up to 7 kg can be moved.

Solution
Due to the challenges of the system, the designers were also faced with the question of how to optimise the routing of energy, control signals and compressed air to the gripper. The robot has an internal energy feed-through, but this does not offer enough space for all cables. In their search for an external energy feed-through, the designers came across the multidimensional movable energy supply system triflex® R from igus®. This energy chain was specially developed for robot applications. It is multi-dimensionally movable and adapts to all movements in the sixth axis, even with more complicated handling tasks of the robot. The small bend radius creates the conditions for space-saving installation. At the same time, external stop-dogs for radius and torsion ensure that the defined radii are not undercut, minimum bending radii are maintained and a long service life of the cable can be guaranteed.
The energy chain is also made of extremely abrasion-resistant material, which has the necessary classifications for cleanroom technology.
igus® supplies the triflex® R-energy chain of the new handling system as a ready-to-install "readychain®" energy chain system, each with a pre-assembled servo and resolver cable (for the two Bosch Rexroth and Indramat servo drives), two compressed air lines and a bus cable for the control signals.
The new system is not only technically convincing, but also economically. Robots have become much cheaper in recent years and the availability of the robot is significantly higher compared to the linear units. Costs are also saved on the energy supply, as only one energy chain is now required instead of the previous six.

plastic for longer life: also maintenance-free plastic plain bearings
For the new handling system, igus® (company mission: "plastic for longer life") not only supplies the energy supply. The spindle drive of the complex gripper is mounted in an iglidur® plain bearing made of high-performance plastic with permanently "built-in" lubricant. This offers several advantages over a conventional ball bearing: Weight is saved, no separately supplied lubricants are required and you can be sure that you have realised a durable and abrasion-resistant bearing - maintenance-free. At the same time, the lubrication does not release any components into the environment, thus maintaining cleanroom conditions. Schmid has extensive experience with this type of bearing. In other system series developed and built in Niedereschach, more than 100 iglidur® plastic plain bearings already ensure smooth motion sequences - in the truest sense of the word...