Special Purpose Vacuum Forming Machines
This is a special purpose Vacuum forming machine of forming area 600 mm x 600 mm to manufacture water cooling fills. Machine is a roll fed continuous in line vacuum forming machine with plug assist options. The sheet material is roll form is fed in the machine where it is conveyed in spiked chain through the heating zones, forming station, Edge trimming station are finally to transverse trimming station. Machine is design for thermoforming of RIGID PVC, HIPs and ABS materials. The machine is fabricated from Mild Steel sections and pipes by welding. The main base frame of the machine will be of rigid construction and no additional foundation in concrete will be needed for the machine. Machine should be mounted on anti-vibration pads.The frame will be clad in sheet metal covers for operator safety, emergency stop buttons at indeed and forming station and printed safety instructions. A manual three way dump valve for shutting air supply to machine is provided. Filter regulator and lubricator is provided for all pneumatics in the machine. Care is taken to ensure easy accessibility of all parts for easy setting and maintenance of machine. All moving parts in the forming station are made from hardened and ground steel components moving in business or bearings.
Photos
UNWIND STATION
: It is a heavy duty frame capable of handling rolls upto 800mm diameter and 700mm width maximum. One air expansion shafts is provided along with the machine. The roll stand is equipped with a passive tension brake. The material is pulled by a set of nip rollers and the excess material forms a loop at the front of the machine. The length of the loop is controlled by an electronics eye. An air gun is provided at the front.
PINCHAIN AND RAILS
: The sheet fed from the unwind station to the machine by spike chain throughout the machine. At the entry of machine Stainless Steel tray with side guide is provided where Edge preheaters are placed at each side of sheet which are 650mm long for preheating of the sheet prior to piercing by pin chain. The pin chain rails have free rotating grooved round engagement shoe each. The pin chain are ½” pitch chain. The chain rails can be adjusted in width from 350mm to 660mm by hand wheels. The rails are guided by lead screws and guide rods which ensure width adjustments. The chain is indexed using a motor and drive system along with shaft encoder which is controlled by PLC. The indexing length can be set from 300mm to 650mm. The accuracy of the sheet indexing systems is + 0.5mm. The chain rails have brass guides to ensure smooth movement of the chain. Each rails has adjustable hold down bar for accepting difference thickness of sheet. Each rail has a water cooling jacket of 25mm square pipe along with the entire oven length
HEATER
: The heating zone comprise of upper heater which is 1825mm long and is fitted with 245mm x 60mm ceramic infrared heaters of 650W each. Each heater is mounted on polished SS Reflector. The heaters are arranged in 9 rows of 7 elements each. The heaters can be moved in rows to give heating pattern in rectangular to parallelogram fashion. The tilting range is from 0 to 35 deg. individual temperature controller for each row. The distance of sheet from heating panel is 100mm. The heater panel can be lifted by pneumatic cylinder for maintenance and emergency shutdown. Each heater can be individually switched ‘ON’ and ‘OFF’ by toggle switch.The heating zones are controlled through PLC.
FORMING STATION
: The station consists of Bottom Platen & Top Platen. The bottom platen carries the clamping frame guided by four guides. The mould is mounted on top platen and is driven by one cylinder mounted on the top platen and has its four guides. The mould platen has full air, vacuum and chilled water services. The speed of all the cylinders for each direction is controlled by flow control valves and end stroke speed is reduced by adjusting the cushions in the cylinders. Suitable plug assistance can be provided. Air ejection for easy removal of formed part will be provided. The forming station is capable of forming rectangular as well as in parallelogram fashion [from 0 to 35 deg.max] to give continuous fills. The product formed is cooled using water cooled mould and optionally air jet cooling for top surface can also be provided.
TRIMMING STATION
: From the forming station the formed product moves on a stainless steel top to the trimming station. The trimming station consists of 2 rotary cutters.The cutting length can be adjusted in multiples of set indexing length. For example if indexing length is set at 550mm, the cutting length can be either 550mm or 1100mm or 1650mm etc. The formed fills moves on to the conveyor after being cut by transverse cutter. The conveyor length is 3000mm approximately. Side trim collection tray provided.
PROCESS CONTROL
: The entire control sequence during the automatic and manual modes is controlled using Mitsubishi PLC control with Touch Screen interface of size: 10.4”. The time and sequence are programmed in the PLC while the heater temperatures have to be set separately on the controllers provided. The PLC is programmed for delay timers for sheet indexing stoppage and mould closure failure. The heating oven opens automatically when sheet indexing time or forming time exceeds the set delay timers to prevent excessive sheet heating. The electrical circuits for power and control circuit are housed in an fan cooled free standing placed at the front of the machine near the right side of operator.Circuit breakers are provided for all major sub circuits and overload relays for all motors. Main isolator is provided on the panel.
