The welding operation is simple enough, it projection welds at four points to join a bracket to a plate. But, there’s more here than meets the eye.

Three holes in each of these two parts must be properly aligned to ensure correct positioning of three steel tubes that are subsequently welded into each sender unit. Peak engineers used a machine vision system and precise fixturing to achieve the correct alignment. The fixture design facilitates easy modification to accommodate any future changes in part configuration.

Each machine has a 6-ft. diameter index table with eight stations. There are two fixtures at each station to handle two different size sender units. The largest round plate is 5.4 in. (138 mm) in diameter; the smaller one is 4.6 in. (113 mm). Both sizes of units are run at the same time on these machines. (There are numerous combinations of each family (113 mm & 138 mm) of parts that run in the fixtures.)

Here’s a "bird’s eye" description of the indexing table:

Station 1: Load (manual). First operator loads the plate and bracket for the large assembly

Station 2: Idle

Station 3: Load (manual). Second operator loads the plate and bracket for the small assembly

Station 4: Projection weld four spots on the large assembly

Station 5: Idle

Station 6: Projection weld four spots on the small assembly

Station 7: Idle

Station 8: Unload automatically

As noted, the location of the bracket on the plate is critical for proper alignment of three holes in each of the two parts. One of the tubes ultimately mounted in one pair of holes is designed to carry a float for determining the fuel level in the tank. If the two hole centers are off just several thousandths of an inch, the fuel gage reading could be significantly in error.

Locating pins and ceramic tabs in the 16 Peak-designed fixtures ensure that the two parts are lined up properly prior to welding. This is confirmed with the use of two Allen-Bradley cameras mounted overhead at the second loading station. Should the parts be mis-aligned in either of the two fixtures, the vision system signals the machine to stop.

The two projection welders on the first unit were built by Newcor. The welders on the second machine are by Taylor-Winfield. Welding can be done on both stainless steel and terne-plated steel. This is an advance over previous welding systems used for these operations. The earlier systems could only weld terne plate, and the accuracy of the welded assembly was a problem.

A small pick-and-place device built by Ferguson is used for automatic unloading at station eight on both machines. Each welder is controlled by a Robotron 400 weld control. The entire 8-station welding system is sequenced with an Allen-Bradley PLC-5/11 controller. The production rate per machine is 1500 assemblies per hour.

These two welding systems, running reliably at Ford since 1993, are representative of the special machines, tools, and fixtures designed and built by Peak Industries. Examples of other precision equipment delivered by the company include transfer systems, assembly systems, blank destackers and loaders, and high-pressure wash and deburr systems.

Peak Industries has been a supplier of custom automation and assembly components and special machines and systems for the automotive and other manufacturing industries since 1966.