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fects reliability of pipe bending machine performance and its safety for environment. New machines don’t use single loop system for water drain in canalization, and old type machines are constantly reequipped with double loop systems of new type. Double loop cooling systems provide persistence of high quality of cooling water and minimize its consumption. The inner (first) loop is the system of parallel flow channels, and each of them cools any heating element of inductive heating machine. Most important flow channels, which define reliability of inductive heating machine performance, are equipped with detectors of water presence and its temperature. Pump is utilized for water circulation in the first loop. Water inside inner loop is cooled either in heat– exchange unit with service water, coming from outer loop from plant circulating water supply (“water–water” scheme), or by air radiator (“water–air scheme”). Accurate cooling of pipe significantly af- fects the quality of bending. Heating and cooling of pipe is processed by one and the same construction element – the induc- tor, combined with sprayer in order to cool the pipe. Air or water are used as cooling media. Water is more efficient cooler and conse- quently it is more frequently applied in general purpose pipe–bending machines with inductive heating. However, water has various disadvantages and limits, concerned with metal structural changes during cooling process, what requires following thermal processing of bended pipe in some instances. In particular, when bending pipes from steels, containing 0.2 % of carbon or more, water cooling leads to necessity of following thermal processing to remove strains and to restore metal structure. Water cooling of titanium alloys, used in particularly important areas of shipbuilding infrastructure leads to forming of gas–sat- urated layer, constituting upper metal layer, which was formed in conditions of heating in oxygenated environment, and described by high concentration of interstitial ele-


Outer diameter of bended pipe, mm Maximum thickness of pipe wall, mm Minimal bending radius


Maximum radius of bending (carriage), mm Maximum bending angle, degr Speed of pipe line feed, mm/s Power of inductive device, kW Generator frequency, Hz Machine weight, kg


d


v


e


r


t


o


r


i A l


Fig.2


ments in comparison with parent metal. Gas–saturated layer increases danger of crack formations and decreases perfor- mance of heavily loaded pipelines. This layer in not permitted to appear in critical pipelines made from titanium alloys. That’s why they use air cooling for pipes made from titanium alloys. For this purpose they use air from plants main tube with pressure 0.6 МPa. At presence, Russian shipbuilding enter- prises replace old type machines with machines of new type, possessing higher level of mechanization/automation. At first, this type of machines allows to move from traditional pipe–bending based on using the stamp as information carrier of pipe configuration and size to analytic method


73 12


1.5dt 1180


190


0.1–3.0 160


2400 9500


For more information please check site of Joint stock corporation Shipbuilding & Shiprepair Technology Center www.sstc.spb.ru


of bending, which is performed on cold bending machines. Automation of process control of pipe heating is particularly important here. The main element here is pyrometer. Heating temperature of pipe is estimated on outer bend. Pyrometer be- comes critical device when bending tubes are made either from titanium alloys, where range of potential temperature change is about 820–840 °C or from corrosion–resis- tant steel: 1050–1100°C. Fig.2 shows photo of machine UTG–IN–273 during its testing on manufacturers facility (“JSC “SSTC”, Saint–Petersburg). Main techni- cal parameters of this machine are shown below. Such types of machines are currently used for re-equipment of pipe–production lines of shipbuilding enterprises.


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