3. CUTTING
Control of cutting is performed on the ground of data base created by TRIBON system. If cutting machine is joined to TRIBON server directly then control is performed basing on the data base of the hull shape, as in Szczecin Shipyard. Otherwise there is the necessity to create control files, which should be copied to external carrier (floppy disk, record, conveyor belt) and transferred to an operator of cutting device.
Shapes of hull elements are recorded as straight and bow lines in co-ordinate system related to the definite point of the plate, so the basic requirement in cutting operation is to place the plate in right position on the cutting table.
4. WELDING - USE OF AUTOMATICS AND OF ROBOTS
One of the most arduous works in shipbuilding process of the hull is welding in narrow spaces of cofferdam sections as double bottom, double ship's side or bulkhead. Especially working in double bottom is a time consuming operation because of many stiffeners crossing on every frame and uncomfortable work position of welder.
A large number of welds of considerable length causes heat deformations of the hull. Further process of assembly will demand corrections of construction shape, application of sophisticated tools for inspection and supervision of work quality, specially worked out technology for non-typical joints. Additionally, the weight of hull sections (hundred tons) does not permit to use positioning gear widely. Hull sections are placed in accidental manner, straight on the floor of assembly workshop.
The solution eliminating these inconveniences can be introduction of welding robots executing most of connections welded in unfavourable conditions repeatedly with the optimal parameters of process.
Control of welding robots on the ground of data obtained from the hull data base can be insufficiently precise. In the TRIBON system data of weld course and of shape does not take into account thermal deformations nor work inaccuracies mostly (for example: beginning of line at point X1, Y1, Z1 and its end at point X2, Y2, Z2). It could happen that weld would become situated wrongly because of that theoretical data only.
Regarding precise leading the electrode along welding crevice there is the necessity of application of robots working in "on-line" mode, which allows the continuous control of welding, fig.3.
Fig. 3 Changes of the crevice shape caused by heat
