Excel Automation, the UK’s leading manufacturer of material handling equipment, has designed, manufactured and installed a slat conveyor and shuttle handling system for a new excavator assembly facility at JCB Heavy Products in Uttoxeter.
JCB, the family owned manufacturer of construction, agricultural and groundcare machinery, produces over 300 different products on 5 continents. The 25-strong tracked and wheeled excavator range covers vehicle weights from 7 to 46 tonnes and is built in two parts comprising a lower frame carrying the tracks or wheeled chassis; and an upper revolving frame that houses the engine, cab and excavator attachment.
The lower frame is assembled on an operator-controlled indexing conveyor; the revolving frame is assembled on a continuously moving track; and the two are brought together for final assembly using a transfer shuttle. The whole system, including the shuttles, was designed, built, manufactured and production-ready tested by Excel Automation at its Worcester factory.
The lower frame line features seven stations with the lower frame initially inverted to allow components such as track motors and couplings, hoses, lower track rollers to be fitted and connected. The frame is then turned over and the top rollers are fitted while the tracks are being laid out over the next two stations. The frame is then lifted onto the tracks, which are wrapped around the machine and joined up. At the final stage the tracks are tensioned before the lower frame is lifted onto a shuttle by an overhead crane.
The main revolving frame line, travelling constantly at 0.13 – 0.18 m/min, is equipped with special fixtures to hold the revolving frame in place as it moves through eleven build stations, where assembly operators attach components such as the main control valve, engine, radiator and oil cooler, hydraulic and fuel tanks, operator cab; and a ‘house’ frame that carries doors, bonnet and top panels. At the end of the line, following final inspection, the revolving frame is lifted off the line by the overhead crane.
To receive the revolving frame, the shuttle with the lower frame onboard (weighing up to 13 tonnes) moves to the revolving frame docking position where the revolving frame is lifted, lowered and docked on the shuttle, which is designed to accommodate a combined weight of up to 26 tonnes. The shuttle is then called to one of two off-load stations where the docked machine is transferred into the corresponding attachment fitting lane. The shuttle is then called back to the lower frame position for the process to be repeated
The Excel-designed chassis handling system has four lines: the tracked lower frame line; the revolving frame line; a wheeled chassis line; and a wheeled revolving frame line. The latter two can be automated in the future.
Whilst the constantly moving revolving frame line typically travels at 0.13 – 0.18 m/min, the speed can be adjusted to suit the various machine builds. Because the steel tracks for the lower frame need to be laid out side by side, taking up two stages, an indexing conveyor is used. This is controlled by the operator at each station pressing a ‘stage complete’ button.
As well as the JS range, the Excel lower frame conveying and handling system is also used to assemble three models in the more compact JZ (zero tail swing) range, which has similar undercarriage with a smaller revolving frame. In addition, one of the two shuttles is used to move wheeled chassis to be docked with wheeled revolving frames when the facility assembles wheeled JS excavators ranging from 13 to 20 tonnes.
Commenting on the completed Excel system, David Taylor, Manufacturing Engineering Manager, JCB Heavy Products says the project was a challenge.
"Whilst Excel has a lot of experience, its automotive projects have involved cars and car components and we were asking its engineering team to move large tracked vehicles weighing 26 tonnes. We discussed the project at great length to ensure that Excel understood exactly what was required for the assembly lines; and their response was very professional."
He confirms that they rose to the challenge very well and, as a result, the whole operation was carried out to a tight schedule over three months. He reports that the equipment quality and the design and build of the conveyors and shuttles were very good. He adds that Excel’s input on operational health and safety was also invaluable, ensuring that JCB assembly staff interacted safely whether working on the constantly moving revolving frame line or the operator indexing lower frame line.