CTC device for folding raw hides

One of the most difficult and tedious operations carried out in the leather process consists of folding raw skins (in 4, 5 or 6 folds, according to the size) in order to pile them onto a pallet. This is usually done directly onto a pile on the ground although, in the best of cases, it may be carried out on a table. Operators sometimes find they only have 15 seconds to carry out this task. The skins are heavy, normally ranging from 30 to 50kg, and occasionally reaching 70kg and measuring up to 3m x 3m. They are salted, filthy, and either extremely rigid or supple, both making them very difficult to manipulate. CTC's objective was to create an automatic folding machine which is trustworthy and fast enough to respond to the needs of hide traders and abattoirs, whilst alleviating the strain on the employees involved. The project aimed to achieve a working rate of 1,600 skins per working day of 6.75 hours. In the design process, particular attention was paid to safety, simplicity and robustness of the machine. The results of the project The machine is made of seven conveyors, six of which are independent articulated flaps. The unit is fed by another conveyor which brings the hide to the centre of the folding device. Once the hide is in position, the six flaps tip up one after the other to give a folded hide of 0.6m x 0.6m meters. The rocking motion of each flap is achieved in less than one second with an angle of about 80 degrees. This movement is sufficiently abrupt to throw the hide into a fold and, when the folding is finished, the hide is automatically ejected onto a third conveyor. The machine offers four main advantages: * Very high productivity, up to 360 hides per hour * The work is much easier: feeding, folding and discharge require no manual handling * The quality of the folding is consistent * The process now needs just one operator instead of the two needed previously. This operator stops the conveyor with a button to centre the hide; in the future the operator will be replaced by a video camera. A prototype has been running successfully at SOCOPA Cuir since July 2002. After a short period of adaptation in the factory, the folding rate passed from 170 skins/hour to 245 skins/hour, which equates to 14.7 seconds per skin. During the trial, SOCOPA personnel warmly welcomed the arrival of the machine. It was taken up quickly as it is simple to use. Adjustment was only necessary when changing from small to large skins. The two workers previously in charge of folding the skins by hand were moved to surveillance tasks or peripheral jobs. M Bélliard of SOCOPA leathers stated at the time: 'This machine of complex conception and innovation has been installed in a very short time and been integrated into our production line without any great disturbance to our rates and habits. The employees who use it are satisfied with its performance and with the manner in which CTC has reduced the nuisance factor.' The automatic folding machine was patented via an international procedure in February 2004. Folding capacity * Maximum dimension of flat skin: 3m x 2.8m * Dimension of folded skin: 0.6m x 0.6m * Maximum weight of skin: 70kg * Time of total cycle: 10 seconds Objective Replacing a manual operation of folding raw hides by setting up an entirely automatic process Interest * Elimination of a tiring task for the operators * Regulation of the production cycle Result - see Figure 1a and 1b. Implementation of equipment comprising conveyor and six articulated flaps: * The flap rotation is ensured by gear motors controlled by a speed variator (acceleration and deceleration) * The under-frame and the flaps are constructed from stainless steel in order to resist salt corrosion * The safety of the operators is ensured by a barrier which belts the folding flap * The invention was patented on February 4, 2003 * The folding equipment has been working in an industrial environment at SOCOPA Cuir since July 2002