Automating Body-In-White

March 1, 2005
Modular bodyshop systems automate automotive manufacturing.

Modular bodyshop systems automate automotive manufacturing.

By Leslie Gordon
associate editor

ABB's roller-hemming cells can feature multiple robots — one robot hems the part's upper section, while the others do the sides and bottom.

A roller-hemming robot bends, then flattens, the edges of car doors, deck lids, hoods, and other automotive products, finishing the part peripheries by making a hem.

Shops know that to stay lean and mean, they must simplify and standardize their operations. But how to best achieve this? ABB Inc.'s Robotic, Automotive and Manufacturing Group, Auburn Hills, Mich., believes robotic automation is the answer. Practicing what it preaches, the company devises automated robotic systems comprising software and machines that boost the efficiency and productivity of even the most difficult processes, such as those used to manufacture cars.

A recent example is the company's proprietary automotive-bodyshop software, which stores and transfers huge amounts of vehicle-manufacturing data and information. Another example is the company's body-in-white system, part of its modular bodyshop made up of several automated cells, including ABB's new robotic hemming cell. These cells, called Plug and Produce modules, extensively use robots and constitute mini assembly zones. The cells hook together to create a complete bodyshop.

Simon Mathieu, director of market development for body-in-white systems, says the company implemented robotic systems because of the need for flexibility and the lack of floorspace facing most automakers. "Companies want to get more efficient," says Mathieu. "During the last five years, carmakers took about three years to develop a vehicle. The modular bodyshop now lets them do this in about one-and-a-half to two years."

Optimizing communication
Mathieu explains, "Our in-house data-management system automates and optimizes communication, both between us and external customers and among internal process, design, and project engineers." To do this, the system includes spreadsheets containing customer part, spotweld, and GD&T data — and it integrates with visualization software.

The software databases hold part data such as vehicle type, part number, part arrival history, and the assembly station affected. Spotweld data comprises coordinates of the weld, parts welded, line, station, weldgun, spotweld (SW) number, and vehicle type. And GD&T data includes arrival history, coordinates, GD&T number, type, and station number.

"A customer's record may contain, for example, five different vehicles, each with approximately 700 parts." Mathieu says. "If a customer changes one part, there is a ripple effect impacting the entire assembly process for all five. But large as it is, the data-management system lets customers easily check such ramifications."

Customers typically transmit their vehicle information to ABB in CAD files via the Web. The software then converts the data into robotic simulations and stores the information in several databases. When the customer transmits new data, system macros automatically search these databases, comparing data to update the part, SW, and GD&T information.

The system links with simulation software. This lets it use visualization tools to, for example, verify a new part release once it detects a modification and determines the impact of the change on tooling, weld-gun accessibility, and cycle times. In this case, a color-coded graphic displays unmodified, added, and deleted surfaces. Here, the graphic also shows the impacted spotwelds and any potential collisions with the welding gun.

When all looks well, the software creates a communication sheet for customer approval. Once the customer approves, modifications go to ABB's design department. Mathieu explains, "By keeping a part history, we can remind the customer how many times it has changed a part — the history becomes a living document. Another big benefit is the system is PC-based. The customer doesn't need expensive, high-end CAD software or roboticsimulation software. Instead, it can simply send PowerPoint or Excel files, knowing the recipient has the same level of information."

Mathieu explains the software has application for small shops with one robot, as well as large manufacturers with hundreds. However, if a shop is only dealing with one car model, the software would probably be unnecessary. But if the company has one model and is going to be introducing new models in the future, the software gives them a frame to automate their processes.

Robotic hemming
Also part of the modular bodyshop is the company's new automated robotic roller-hemming cell. In the hemming process, the edges of car doors, deck lids, hoods, lift gates, and other automotive products are bent and then flattened, which finishes the peripheries by making a hem.

Typically, this process is done with large presses, which have quick cycle times but are not flexible. Presses are also costly to tune-in — if a company has five models of automobile, it needs five different presses. This takes up a lot of floorspace and requires a high investment. So, in lieu of presses, ABB provides automated systems with robots that do the hemming. Hemming cells feature one robot or multiple robots, depending on the production volume. An optional robot loads and removes parts from the cell.

On the end of each hemmingrobot arm is a special roller tool. The robots finish peripheries by going around the panel edges, bending a lip of the metal over with the edges bent in successive passes. Mathieu says having multiple robots makes hemming exceptionally fast. One robot does the part's upper section, while the others are hemming the sides and bottom. And the hemming robots use small rollers that easily get inside small areas or small curves, which can't be done with presses.

The robots handle one part or many. For instance, an OEM customer may want one automotive side panel for a service part or prototype. With a roller-hemming cell, a company can cost-efficiently run just the one panel in a short time. Therefore, it doesn't have to keep a large inventory, and it can respond quickly to customer demand.

"Roller hemming is also a big advantage when bending certain types of material such as aluminum 6111," Mathieu continues. "This type of aluminum provides an excellent ratio between way and rigidity of the part for crash testing. However, with typical hemming processes, 6111 tends to crack. Roller hemming is a much smoother process then hemming with a press, and it doesn't damage the metal's crystalline structure.

Because it's just a rolling action and there is no friction, wearing is minimal, which reduces maintenance costs.

For its next-generation Plug and Produce modules, ABB is developing RobotStudio, a PC-based robotic simulation and off-line programming package that can handle synchronous motion, where robots work together, or asynchronous, where they work independently.

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