EDAG, Detroit, MI, a development partner for the transportation industry recently had to design a heavy-duty ring for a new production concept. For small lot production of vehicle components, this ring had to bear the weight of car body tools weighing up to 4 tons, and deliver sufficient room at its center for a heavy-duty robot.
During initial development, EDAG engineers found that the heavy-duty rings currently available were too small to bear the weight of four heavy car body tools and provide sufficient room for handling systems and a robot in the center.
EDAG’s Managing Director/COO Manfred Hahl commissioned WEISS North America, Inc. (Willoughby, OH), and its’ parent company WEISS (Buchen, Germany), specialists for rotary tables and automation, to initiate detailed and collaborative engineering discussions to develop a complete, integrated solution for this unique production system. WEISS engineers began custom engineering specifications on a CR 2600 rotary table that could ultimately accommodate four tools and a robot in the center.
The design goal was to design a rotary table that could efficiently accommodate four tools. While production is underway at one or two positions, the free positions must then be either manually or automatically equipped with new tools. The table should also feature sufficient space in the center for a robot to carry out both machining and logistics functions—saving space while enhancing system flexibility and productivity.
Key specifications for the CR 2600 heavy-duty ring quickly came into focus:
- A permissible vertical axial 500 kN dynamic and 1000 kN static force on the drive plate
- A central opening of 2 m and a freely programmable drive
- A low installation height of 300 mm to enable stepless, ergonomic manual loading alongside automatic loading
Additionally, the ring would have a flat design, zero backlash and good power transmission as well as a drive unit positioned far to the outside that can easily be operated with WEISS Application Software (WAS).
According to Stanislav Cafuta, a WEISS system developer, ”The key was designing the ring‘s central opening with a diameter of 2 m, tool weights of up to 20 tons, and a reach of up to 2.5 m – demands that even our largest heavy-duty rings were unable to meet at the time.“
Several technical hurdles had to be overcome before the new generation CR 2600 achieved its goals. A critical part was the bearing. The development of a so-called YRT bearing, a combination of two axial bearings and a radial bearing, is a time-consuming matter. WEISS engineers decided to speed up the process by giving the bearing supplier Schaeffler (Fort Mill, SC), a helping hand by assuming responsibility for the development of the bearing cages themselves. This action compressed the total development time and delivery for the CR 2600 to six months.
Featuring a large central opening, the ring is a combination of a classic rotary table and shuttle system in which robots can access a workpiece from both sides. The system is currently running with two tools for two components, so that the rear hatches and bonnets can be manufactured in a combined process.
According to WEISS North America’s Vice President, Bill Eppich, “Ultimately, the CR 2600‘s configuration opens up other possibilities for the installation that sparks the imagination. This is due to the user-programmability of the table, as well as savings in floor space brought about by the option of positioning even large robots at its center.“
EDAG’s Hahl expanded on these possibilities stating, “For example; if an opening of two meters can accommodate one large robot, then there is of course room for two or more small robots. In addition, four or more different tools can be used instead of the current 2+2. It is possible to either produce four different door types for small lots on one installation, or provide four different tools in quick succession in a similar manner as a turret on a machining center.
WEISS North America, Inc.
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