Robots link drop forging process

The robots handle so-called billets downstream of two saws, unloading the blanks from a spiral conveyor, placing them on a furnace conveyor, loading and unloading the preforming press, and transferring the preformed blanks via a stillage to first the blocking die and then the finishing die of the main forging press, before placing them in a trimming press. This press is unloaded by a robot mounted in an inverted position, which sets the finished forging down on a cooling line.

Because Buderus Edelstahl Schmiedetechnik GmbH uses the system to produce shafts, crown wheels, steering knuckles and gears, the press dies have to be exchanged. This can involve a changeover from one family of parts to another, or within a particular family. A changeover between families means that the pincers and grippers for five or six robots have to be exchanged. Within families, only the gripper jaws have to be changed.

Well-trained operators program the robot and monitor the entire system. The robot controllers communicate with the higher-level central controller via Profibus. It is possible to modify individual parameters of the system, such as press forces and temperatures, without interrupting production.

• Ten Series 2000 KUKA KR 210 robots
• Ten PC-based KUKA robot controllers, including control panel with familiar Windows interface
• Two hydraulic gripper types, exchanged when switching to a new product family
• Robot programming
• Commissioning

The system was supplied by the press manufacturer SMS Eumuco.

Highly heat-resistant

The foundry version means that the robots are adapted to the harsh conditions in forge shops and foundries. They have special paintwork and special seals at their motor and gear unit flanges. This makes them resistant to the very high temperatures of the forgings, as well as to moisture and dirt. The robots’ foundry wrists are painted aluminum white, and hold gripper tooling made of special heat-resistant steel. The result: even more heat resistance for this particularly critical area.

High flexibility

The maneuverability of their six axes means that the robots are significantly more flexible than a walking beam unit. Another aspect of their flexibility is the ability to implement semiautomatic sequences for forging and trimming.

Output doubled

By using the robots it was possible to nearly double the output of press line 1 compared to a comparable line with three operators per shift, which achieves an average hourly production of 1.5 tonnes.

High availability

Also of note is the availability of the robots in three-shift operation; despite the very harsh conditions, availability has exceeded expectations.

Greater variety of parts

The automation solution enables the user to manufacture parts which could not be produced manually.

Working in an inverted position

One of the advantages which helped KUKA to win the contract was the fact that KUKA robots can be operated in an inverted position – even in the size required for this application.

Time savings

Normally, main forging presses use only one die per press stroke. Because, however, the two robots installed at this 8,000 tonne main forging press can work in parallel, two dies are used for part of the product range.