Tesla Tier 1 supplier installed an automated tandem line comprising six YANGLI presses and ABB transfer system for a direct parts transfer from press to press.
When you begin to look at a program to produce the best-quality automotive components at the highest yield rates—and throw a new material into the mix—there are a plethora of details to consider that will impact the end deliverable.
If an OEM or tier stamper wants to install an automated system to stamp its large automotive components, it must first consider all the variables such as general press configuration, press stroke length, die space opening, interference points, speed, tonnage and energy required, and scrap removal.
Tandem or Transfer. The OEM or tier stamper must first choose the general press configuration, such as a transfer press or press-to-press line.
A transfer press requires all the components to be nested in the die before cycling the press. In a tandem line, the press can cycle once the individual component is nested in the die.
In a tandem line, the presses are synchronized by a variable press shift–typically 60 degrees from each other so that press 1 will reach bottom dead center first, then press 2 will reach bottom dead center 60 degrees later, and so forth. The press center-to-center distance should be as short as possible while still allowing press repairs and maintenance. This serves as a baseline for the press placement and all other component placement.
Press Stroke Length, Die Space Opening. The press stroke length and die space opening need to be big enough to allow the components to be loaded into the dies with stability. In most cases, that requires transfer automation with two arms, as well as a wide opening for the left-to-right die space.
If a single-arm transfer is used, such as a robot, the automation will cost less, including the cost for the left-to-right press opening, because it will be smaller, but the trade-off is a less stable component because it may need time to settle and stop bouncing before being placed into the die. Full control of the component during the transfer from die to die, under acceleration, deceleration, and G forces, becomes critical.
Speed, Tonnage, Energy. The required press speed, tonnage, and energy need to be enough to produce at the required rate, and the slide motion, such as a standard eccentric drive, link drive, or a servo-mechanical press, needs to be considered. All other variable slide motions and various interference curves that come into play to accommodate the optimal slide interference/displacement curve must be considered as well.
Interference Points. A review of automation integration into a press configuration should include looking at potential interference points, such as gib drip trays, oil return lines between the uprights, slide tracked vehicle tracks, control switch brackets, air automation valve connections, and bed-mounted equipment such as bolster clamps. If interference is encountered, the OEM or stamper needs to design around the interference or relocate it to permit the required clearance using a simulation tool.
Scrap Removal. In stamping operations, scrap removal often is an afterthought. It’s best to design ahead. Scrap shedding, both through the bolster and bed, as well as scrap doors on the front and back of the press are must-have design features.
Automotive OEM Case Example
An automotive OEM studied how to stamp its automotive body panels, such as hoods, doors, fenders, body sides, and many of the corresponding inner components. The parts were to be formed from both aluminum and steel.
Beginning with the general press configuration for the body panels, the automaker chose to use a tandem line in the belief that this would be incrementally faster than a transfer press.