Linear drive technology with laser sensor system and safety engineering
Knowing User Demands
Effectively quality testing can be accomplished by well-conceived integration of quality control into the production process. In addition to testing expertise and the appropriate inspection technology, such a step also requires reliable and dynamic materials handling engineering.
Fig. 1: To prevent the synchronised operation of the linear axes from being disturbed by the non-synchronised moving conveyor belts, servo controllers and exactly fitting servo drives of the Accurax G5 family ensure constant motion of the belts
Being able to procure all automation components needed for inspection, handling, and safety engineering from a single source is of enormous advantage to manufacturers of production lines for the PV industry. The Salem-based ATM Vision specialises in the production of inspection systems for quality assurance and in the construction of production machines for the photovoltaic sector. The company cooperates closely with Omron’s automation experts who now also provide drive solutions used in handling systems and for safety engineering.
Perfect synchronisation
Linear drives and their motion controllers face a challenging task in fast and synchronic wafer distribution from one conveyor belt to five belts via a slider system which may be located downstream from a so-called WiS unit. After passing through the inspection unit on a conveyor belt, the wafers have to be distributed onto five separate belts for further processing. Both, the feeding belt and the five belts conveying the wafers to the next processing step, operate continuously. The picking up of the wafers, on the one hand, and their distributed placement, on the other, must therefore work exactly synchronised to prevent slowing down of the overall production process. It is also important to place the sensitive wafers with great care and precision; cycle times are less than one second. This is where the Accurax R88L-EA linear motor axis proves to be an ideal solution. While Scara robots are basically unsuitable for this purpose, Flexpickers could generally accomplish the task. However, linear motor axes actually give the same results for less costs and also require less maintenance. Moreover, their modular nature facilitates ready adaptation to various processes.
Fig. 2: After passing through the Wafer Inspection System (WiS), the wafers are transported to the etching process (Pictures: Omron)
In order to prevent the synchronised operation of the linear axes from being disturbed by the non-synchronised moving conveyor belts, servo controllers and fitting servo drives of the Accurax G5 family ensure constant motion of the belts. Among other effects, uneven running would displace the light wafers on the conveyor belt. The linear drives use the Ethercat communication protocol. In the future, all machine components will work with this communication protocol.
As this drive concept performs perfectly in complex tasks, the company also decided to use this solution in similar, but less complex applications, such as in loaders and sorters. In the case of the loader, a linear axis takes a wafer from a stationary cassette and places it on a moving conveyor belt. A sorter performs the opposite task: Wafers are taken from the moving conveyor belt and are placed in different boxes according to their quality marking. And the linear axes also perform a similar task in inspection systems: Passing wafers are picked up from the moving belt, turned, and replaced to their previous position.
Intelligent modularity
Fig. 3: The communication system of the servo controller works with Ethercat
The strength of linear motor axes is also immediately apparent in a lay-up machine, another unit made by the ATM Vision. The technology background: To produce a solar module, several cells are first soldered together in series with special soldering ribbons in a stringer machine. A subsequent inspection ensures that the individual cells of a string do not have breakages. In preparation for assembly to complete modules, those strings which have passed inspection are precisely aligned on a glass plate, several rows at a time, in a …
Fig. 4: The inspected strings are placed in precise alignment on a glass plate in the so-called lay-up process ready for assembly to a complete module
Authors
Stefan Spiekermann, Head of Strategic Semiconductor and Photovoltaic Industry Sales Team, Omron
Nora Crocoll,
Redaktionsbüro Stutensee
Facts for Decision Makers
Intelligent Cooperation
- Quality testing is indispensable to assure product quality and has be as effectively as possible.
- A well-conceived integration of quality control into the production process and an intelligent modularity of the automation offers suitable solutions.
- The challenge of the fast and synchronic wafer distribution shows the advantages of the used linear motor axis Accurax R88L-EA.
- A close cooperation between a plant manufacturer and a component supplier are the solution focused conditions for success.