Autoclaves for the manufacture and repair of composite parts

Composites or composite resins are heterogeneously mixed synthetic materials forming a compound, as its name suggests. They are made up of molecules of various elements and these components can be of two types: cohesive or reinforcing. On the one hand, the cohesive components surround and join the reinforcing components, maintaining their rigidity and position. On the other hand, the reinforcements improves the physical properties providing cohesion and rigidity.

TASKS OF THE OPERATOR WITH THE AUTOCLAVE

  1. Manual introduction of the platform inside the autoclave
  2. Manual horizontal close of the door (automatic as option)
  3. Automatic door closing system assisted by a hydraulic cylinder.
  4. Start of the programmed curing cycle and automatic lock of the door during the whole process.
  5. Finalization of the selected cycle, door unlock and extraction of the platform with the cured composites parts.

PROGRAMMED CYCLE

Each process is based on programmed segments of temperature, pressure and time.

Each segment is divided in the following sub stages:

· Heating ramp.

· Maintenance.

· Cooling ramp.

The slope of the pressure and temperature ramps are controlled by the PLC.
During the maintenance phase, the pressure and the temperature are maintained during the programmed time. The increments are programmable and usually range between 0.5 and 1 bar/min (for pressurization and depressurization) and between 0.5 and 3 ºC/min (for heating and cooling).

The pressure and temperature can be adjusted while the autoclave is in operation.

The composites parts can be cured into vacuum bags through the vacuum terminals on the autoclave’s cylinder. The composite parts are introduced into vacuum bags, where the temperature and pressure are monitored. Thus, achieving a more optimal curing result.

The heating process is carried out by recirculating air by means of a turbine, located inside the autoclave.

This turbine recirculates the air through a heating radiator. The air flow is regulated through a frequency converter. As an alternative to the battery of electrical resistances, heating can be carried out by means of an oil boiler.

The pressurization process is carried out controlling the air or nitrogen inlet through a proportional valve.

The cooling process is done by introducing air and exhausting the hot air from inside the autoclave.

As option, the cooling process can be performed by introducing water inside of a cooling radiator located at the back of the autoclave. This water, usually at room temperature, cools the air inside the autoclave when passing through the heat battery exchanger. The water inlet is controlled by proportional valves which allow to adjust the cool-down ramp.

END OF CYCLE

When the last stage of the program has been completed and thus, the autoclave is depressurized and cooled down, the door will be unlocked automatically and the operator will be able to open the door to extract the platform with the cured parts to finish the cycle.

The autoclave will be then ready for the next cycle. The duration of the process is variable and depends on the programmed segments and ramps.