This case study relates to work performed at a customer who produces commercial vehicles, to which we have designed and made a system to handle the engines.

Requirements

The requirement of our customer was to automate the handling of the engines and to make it safer and faster.

The skid-line where the engines travels and the shutter-line for preparation of the front pallet are parallel. At the beginning, the handling of the engine from the skid to the pallet was done by manual hoist. This was un-ergonomic and even unsafe for the worker.

Solution

The self-driven line is a path of approximately elliptical shape. It consists of an aluminum profile that combines some electric hidden hinges that serve both to give power and to carry signals to the suspended tray conveyors.

The suspended tray conveyor is a small, self-driven cart that slides on an aluminum profile. it has hinges that enable it to run across curved paths. A hoist is suspended from the conveyor. this ends with a hook to lift the engine.

There is a a fixed loading station where the worker loads the suspended tray conveyor with the engine. Then the engine is placed on the pallet moving on the shifting shutter, which travels at speeds ranging from 1.5 to 6 meters per minute.

This means that the suspended tray conveyor must be able to adapt its speed to the shutter-line speed so that the discharge is synchronized, and then the engine reachs the shutter in the right position and traveling at the same speed, otherwise the operation would not be possible.

Loading station

• Input translation: 20-5 mt/min.......-> 8”
• Descent to safe height: 14mt/min...-> 4”
• Engine hook descent: 14-7 mt/min..-> 8”
• Engine hook.................................-> 6”
• Pallet release climb:14-7 mt/min....-> 5”
• Cycle end climb: 14 mt/min….........-> 8”
• Output translation: 20 mt/min........-> 6”

Total machine cycle: 45” including the

stop&go movement for carts translation.


Suspended tray conveyor transit

• Loading station to store: 20 mt/min.-> 12”
• Store to shutter-line: 20 mt/min......-> 12”
• Shutter-line to discharge: 5mt/min..-> 20”

Engine discharge and return

of empty conveyors

• From start to end: 1,5 - 6 mt/min...-> 40”
• Engine descent: 14 mt/min.............-> 6”
+300mm at 7 mt/min.....................-> 5”
• Engine release...............................-> 6”
• Pre-climb chain release: 14 mt/min..-> 3”
• climb-cycle end: 14 mt/min..............-> 6”


Total machine cycle:

Pallet predisposition 24” + discharge 20” = 44”

Translation time of the conveyor on the return of

empty ones 9,2 m -> 28“

The hook-saddle anti-rotation system

The suspended tray conveyor is equipped with an electric hoist for lifting the engine with a hook that goes to engage the saddle at the high position, which prevents its rotation, so that the engine will not be in the wrong position at the discharge station.

Ensuring production continuity

The use of the old system has been secured in case of breakdown of the self-driven line, therefore the suspended tray conveyors accumulate in a store area, so that the two hoists that were previously used can be used to ensure production continuity.

therefore it has been necessary to build a metal structure, able to hold the line and its load. Load of a certain importance, since an engine of this size weighs over 2 thousand pounds.

Safety

With the introduction of this self-driven line the ergonomic conditions of the worker has been improved, since he no longer has to manually move the engine, which now travels on a suspended tray conveyor with its own engine. With the introduction of this line the worker does not perform manual steps with his arms above shoulder level anymore.

P+© 2011 LOMA srl - automazione industriale - All rights reserved

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