Robot handling system for circuit boards

Profile

• What was needed: Multi-dimensionally movable triflex R energy supply system, which was supplied as a ready-to-install readychain energy chain system
• Requirements: Energy chain must keep up with the high travel speeds and acceleration and be extremely flexible, as robot movement sequences can be freely programmed; every cubic centimetre counts, so the solution must be compact;  the highest demands are placed on purity (cleanroom solution)
• Industry: Photovoltaic and printed circuit board production
• Success for the customer: Energy supply system adapts optimally to all movements; small bend radii result in very compact installation; material has the necessary classifications for cleanroom technology; economic advantage: instead of six cables, all cables run in only one energy chain.

In the new PCB handling system from Schmid Technology Systems, a six-axis robot replaces the linear systems previously used. A "triflex R" energy chain from igus supplies the energy and signals to the robot gripper.

Problem

The Schmid Group, headquartered in Freudenstadt, specializes in the development and manufacture of machines for photovoltaic and printed circuit board production. Schmid Technology Systems in Niedereschach is the center of competence for handling technology. The product range of this subsidiary includes loading and unloading systems. These systems separate, for example, printed circuit boards that are arranged on cartridges and feed them to a processing station via a conveyor belt.
The ever-higher processing speeds and the customers' demand for greater flexibility 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 that can load and unload cartridges with printed circuit boards with cycle times of less than seven seconds. More important than speed, however, is the flexibility of the system. As the robot can be freely programmed, a wide variety of motion patterns are possible - without any modifications or interventions in the hardware. For example, cartridges of different inclination angles can be loaded and unloaded.  The system is completely enclosed because the highest demands are placed on purity when handling printed circuit boards. Therefore, compactness plays a major role - in cleanroom technology, one reckons with cubic centimeters.
An interesting detail of the system is the gripper, which automatically detects the size of the respective PCB. The support plate with the vacuum grippers is made of weight-saving carbon fibers so that you can use a compact 16 kg robot and move handling goods weighing up to 7 kg.

Solution

For the design engineers, the challenges of the system also raised the question of the optimal guidance of energy, control signals and compressed air to the gripper. The robot has an internal power feed-through, but there is not enough space for all the cables. In their search for an external energy supply system, the designers came across the multi-dimensionally movable triflex R energy supply system from igus. This energy chain was designed and developed especially for robotic applications. It is multi-dimensionally movable and adapts to all movements in the sixth axis, even with more complicated handling tasks for the robot. Small bend radii create the prerequisite for space-saving installation. At the same time, external stop-dogs for radius and torsion ensure that the defined radii do not fall short of the minimum bend radii and thus a long service life of the cables can be guaranteed.
The energy chain is also made of extremely abrasion-resistant material that has the necessary classifications for cleanroom technology.
igus supplies the triflex R energy chain of the new handling system as a ready-to-install harnessed readychain energy chain system, each with a harnessed servo cable and a resolver cable (for the two Bosch Rexroth and Indramat servo drives), two compressed air cables and a bus cable for the control signals.
The new system is convincing not only technically, but also economically. The robots have become much more cost-effective in recent years, and the availability of the robot is much higher compared to the linear units. Costs are also saved in the energy supply system because only one energy chain is needed instead of six. 

"The requirements in terms of purity are increasing in all industrial sectors," states the Fraunhofer Institute for Manufacturing Engineering and Automation. Example: Test setup with igus energy chain E14.3.038.0 for measuring particle abrasion - "tested and found to be very good" by the Fraunhofer Institute.

The robot picks up the PCBs from a magazine provided on one of two feed belts and places them on a conveyor belt.

The complex gripper of the handling system receives its energy and control signals via a multi-dimensionally moving triflex R energy chain from igus.

Cable Handling Systems

For the new handling system, igus (corporate mission: "plastics for longer life") not only supplies the energy supply system. The lead screw drive of the complex gripper is mounted in an iglidur plain bearing made of high-performance plastics with permanently "built-in" lubricant. This offers several advantages over conventional ball bearings: it saves weight, does not require separately supplied lubricants and can be sure of having a long-lasting and abrasion-resistant bearing system that is maintenance-free. At the same time, the lubrication does not release any components into the environment: in this way cleanroom conditions are maintained. Schmid has a lot of experience with this type of bearings. In other machine series, which are developed and built in Niedereschach, more than 100 iglidur plastic plain bearings already ensure smooth motion sequences - in the truest sense of the word

The triflex R energy supply system allows complex movements to be performed in all six axes.

The plug connections and connection plates are also harnessed by igus and supplied ready for connection.