Handling and Assembly Machine for Hearing Aids

For many years, the Danish company G&E Maskinteknik has co-operated with GN Danavox in the automation of plastic component manufacture for Danavox's world-renowned hearing aids. G&E, which is located in the town of Farum north of Copenhagen, is well-known for its design and production of specialised machinery for manufacture in the electronic, medical, plastics, and foodstuffs industries. G&E's co-operation with Danavox has resulted in a long series of specialised machinery, from injection moulding machines to machinery for automatic assembly and testing of complete switches for hearing aids.

The latest machine for automating Danavox's plastic component manufacture is a very compact assembly unit for the small filters which are attached to the hearing aid's individually tailored casing in order to protect the loudspeaker from dirt. These filters must be changed regularly and are therefore supplied in a small patented dispenser containing 10 filters. The dispenser is designed to enable a filter to be easily mounted on the hearing aid without the use of tools. The expended filter is also removed using the dispenser and placed in a container which is an integral part of the dispenser unit.

Each dispenser consists of 3 injection-moulded pla-stic com-ponents: A lid, a bottom and a filter component containing the 10 filters. The task of automation was to die-cut the small circular filter discs, insert one in each filter unit, and thereafter assemble the complete dispenser.

The resulting automatic assembly machine is illustrated in the accompanying figure. It is controlled partially using pneumatic cylinders and partially using 2 JVL Step Motor Controllers type SMC15B. One of the step motors is used to transport the filter units onto a small rotary 

 

 

table for assembly and thereafter to transport the units back for assembly with the dispenser lid and bottom components. This movement is accomplished using a gear and spindle.

 

The second step motor is used to turn the table 1/5th of a revolution at a time. With each rotation sequence 2 filters are cut. In the next sequence, these are mounted into place while two new filters are cut.

All of the machine's functions are controlled by an overall PLC, while the movement of the 2 step motors is controlled by programmes in the 2 Controllers. Step motors were chosen for the above functions because they provided the simplest and most economic method to control the movement.

The machine produces 5 to 7 complete filter dispensers per minute and will be installed at Danavox when the final run-in tests have been completed.