BSH needed a significantly higher degree of automation than previous installation, and the ability to make different types of doors on the same machine and better ergonomics, said Hennecke.
In conventional fridge door manufacturing, the foam in the door cures in a drum system, said Hennecke.
In these systems, the mould carrier moves in a clocked rotating movement around a horizontal axis. With this type of manufacture, the operator always has the same workflow at a single station.
Typically, Hennecke said, it is this:
• Removing the finished door from the open mould;
• Inserting the plastic inner and the sheet metal outer side;
• Finally, the mould is automatically filled with polyurethane.
The speed of this process dictates the speed of all the other production steps in the plant, the machinery maker said.
Hennecke said the new plant splits the removal, loading and foaming steps into three downstream stations. The firm added: “This division considerably reduces the cycle time and the setup becomes more flexible because doors cure in a type of multi-storey car park instead of a drum.”
In the first of the new stations, a six-axis robot removes the finished door from the open mould with a vacuum gripper, said Hennecke. The vacuum gripper is designed so that it can transport all model variants of the refrigerator doors, the firm added.
At the second station, Hennecke said, it has simplified the insertion process: Operators place the inner and outer parts into the lower mould half; as the mould carrier is transferred to the third station for filling, the mould closes and reopens immediately. This transfers the metal sheet into the upper part of the mould. In doing so, the sheet metal outer part is taken into the upper half of the mould.
Two mix-heads can be used to pour polyurethane into the mould, said Hennecke. But, the company added that, only one is used for small doors. This, the firm said, allows the moulds to close quickly. For each door type, a foaming program and the cure time is stored in the control system.
After filling, the mould is carried to a free park position within a four-storey structure. The lift, which transported the freshly-filled mould, then fetches a mould carrier with a cured door and moves it to the removal system and back into production, said Hennecke. The firm added that up to ten mould carriers can be used simultaneously.
This "car park system" gives BSH the opportunity to run mixed production where the plant operates independently of door cure time, said Hennecke.
The firm said that this means that door production can be timed with other production stages, further increasing plant efficiency, said Hennecke.