The world’s fastest production line for LPG vessels

Roth Composite Machinery from Steffenberg sets new standards in the mechanical engineering as regards the series production of liquefied petroleum gas vessels using the filament winding technology. The company developed a fully-automated production line containing four winding stations having five spindles each. The high degree of automation of the production line guarantees maximum productivity.
It enables the manufacture of 600,000 LPG vessels per annum (LPG: Liquefied Petroleum Gas). Bernd Fischer, Sales Director at Roth Composite Machinery, declares: “Having a cycle time of 43 seconds per vessel, it is the world’s most effective production line of this type at present. The advantages of fibre-reinforced plastics for LPG vessels are clear, they are significantly lighter than conventional materials and – especially in the case of pressure vessels - allow a higher degree of safety against explosion.” Fibre-reinforced plastic tanks are increasingly used for the storage of fluids or gases. So, for instance, they are suitable for applications with hydrogen or nitrogen.

Impregnating bath with shuttle table for more efficiency

The production line for the manufacture of plastic vessels reinforced by glass fibres is set up as twin concept. Two independent winding stations are placed in one gantry. The time for loading and unloading is in parallel to the productive time. The loading and unloading of the vessels is carried out in a fully automated way by using robots. An impregnating bath with shuttle table for the impregnation of the fibres ensures optimal efficiency. By this, the production interruption periods are reduced by about 80 percent. A patented procedure for an automatic applying and cutting of the fibres being integrated in the fibre delivery carriage enables highest degrees of automation and efficiency. The control guarantees the exactly defined positioning of the fibres onto the vessel. A gantry combination provides for high precision between the spindles and the stiffness of the total system. The tolerance value of the composite material from spindle to spindle is less than two grams.

Special heavy-duty components in use

The machine builder is using special heavy-duty components at each stage of the production line. Besides a blow-moulding machine for the plastic liners, the designed system also comprises the liner pre-assembly station. At this, the boss part is welded onto the liner, the shaft is screwed in, the vessel is pressurized and the liner surface is activated for the winding process by means of flame treatment. The high degree of production accuracy is shown by the minor deviations as regards the bursting pressure of the vessels. An energy-efficient drying oven being especially designed for the LPG vessels ensures optimal product results. Furthermore, an end-of-line and a batch control as well as the assembly of the outer casing and the labeling are integrated. Four handling and assembly robots allow precise and fast production processes. The process data control is effected via a central main computer. At different stations, individual item numbers of the vessels are read out and stored by means of QR codes. Thus, the process data of each single product are traceable and allow for an optimal production and quality control. Roth Composite Machinery offers a remote access service for this production line.

Tailor-made concepts of Roth Composite Machinery

The special machine builder from Steffenberg has been developing, planning and manufacturing Filament Winding Machines for 50 years and has almost 30 years of experience in the development of fully-automated machines in this sector. More than 500 production plants of the manufacturer are already in use all over the world. Advantages of the production lines are the short installation periods enabling that the production processes can start more quickly. The handling of all kinds of fibres - from simple glass fibres to sensitive, highly rigid fibres – also belongs to the know-how of the company. Bernd Fischer emphasizes: “Our industry-leading design engineers providing
qualified configurations, designs and itemizations develop tailor-made machines for the production tasks of our customers. The results are efficient, reliable and durable machines.“ As general contractor, Roth has the know-how for the conception of complete production processes from the filament winding technology to the demoulding. This includes the design and development of components as well as the prototype manufacture. Roth gives advice as to the material selection – e. g. concerning the fibres to be used – and offers detailed analyses and proposed solutions for all refinements in the manufacturing process. In the course of this, the product specifies the production method.