Applications Cool News from Cannon Innovative solutions for the Refrigerators and Freezers Industry
The world's domestic refrigerator manufacturing capacity is undergoing significant change in shape and geographical distribution. Western manufacturers are looking for a more competitive cost structure for their products and their factories are going to East at an increasing rate. Joint ventures are being made with Chinese appliance manufacturers in order to establish manufacturing sites where labour is still cheap and quality can be assured thanks to sophisticated production equipment. Cannon have been present in refrigerator's Companies in Far East Asia and China for more than thirty years, and keep supplying advanced solutions to these Countries. Innovative cabinet and door foaming plants have been designed specifically for Japanese and Chinese fridge makers by the Cannon Group's Division in charge of this technology.
The technical solutions most recently developed for Sharp consist in a new version of the famous Cannon Drum System, the rotary moulding device that was patented by Cannon back in the early 1980's and has been manufactured in thousands of units and various versions. With the EasyDrum the rotary 6-stations machine is used as a simple carrier for the polymerisation of the foam: the door's closed moulds are automatically handled in and out from the EasyDrum at every foaming cycle: opening, demoulding, cleaning, insert positioning are performed in the front position of a rotating table holding two mould carriers. When the manual operations are finished the table quickly rotates and the open-mould foam pouring and mould closing operations can be performed on the rear position of this service station.
lateral walls, and brings a newly foamed cabinet to polymerise in the upper floor of the plant. This allows for a doubled foaming capacity per single production line: while the service operations are performed in the lower floor (a cured fridge is demoulded from its fixture, a new empty shell is introduced, the fixture closes, the mixing head injects foam from the compressor area, the foam starts rising and fills the cabinet until it is mechanically stable) the polymerisation occurs in the upper floor.
A dry cycle of 1 minute has been achieved, which allows for a very high production rate per foaming line. Actual part-to-part cycle, of course, must be calculated in accordance with the reactivity of the used formulation: the gel time will set the moment when the fridge can be safely rotated without spoiling the foam's quality, and the curing time will set the moment when the fridge can be safely extracted from the jig without risking post-expansion deformation.
The proposed solution is very convenient for manufacturers of large lots of the same model: in this case, in fact, the mould change will occur as it was done many years ago, before the Rotoplug revolution, by translating the old plug out of the jig in a service cabinet, and fitting the new one in place with the same method.
For large serial production the RotoJig brings numerous advantages, in terms of investment, space occupancy and plant's energy management:
In the new V.A.I. foaming system a certain degree of vacuum is applied inside the cabinet, providing better foam filling and higher thermal insulation values.
• A 50% reduction of all loading and unloading lines and ventilation systems (a particularly expensive item in case of Hydrocarbons-blown foams)
• A 50% reduction in mixing heads and related hardware, controls and software, when using fixed injection heads.
• A significant cost reduction when buying a double foaming jig rather than two simpler single stations.
• A much smaller plant's footprint and total volume, an especially valuable saving where industrial buildings are sold – and heated - at a premium price.
• An optimised use of the polymerisation jig, where all the service times are “hidden” behind the longer polymerisation phase and productivity per line nearly doubles.
Innovation, at Cannon, continues as usual, in spite of fluctuant world's economics: designing efficient and easy-to-use energy saving solutions is the mission of the Company.
“The Evolution Continues” at Cannon!
Mixing head’s development: an ongoing committment!
The EasyDrum, a rotary 6-stations machine, is used as a simple carrier for the polymerization of the foam: the door's closed moulds are automatically handled in and out at every foaming cycle.
The polymerisation machine therefore works at its maximum efficiency, not being delayed by dead times. The moulds can be simpler and cheaper than usual, not requiring a thermostatisation circuit: temperature conditioning occurs on board of the EasyDrum, where flat, heated platens of 3 x 1.5 m size are constituting the mould carriers. Production efficiency is very high, of course depending from the curing time of the rigid foam: two large doors can be demoulded every 52 seconds, and the single required operator has a long time, at least 48 seconds, to download the filled doors and load the metal frames for the production of the next two.
For the cabinet's manufacture an innovative version of the patented Rotoplug System has been designed and built. Introduced in the early 1980's by Cannon, the Rotoplug has revolutionised the refrigerator cabinet's manufacturing methods: the possibility to use a double plug on a single foaming station allowed for easy mould change on one side of the upper rotating platform holding the plugs, while the other, below, was in Polymerisation phase. In the new version of this successful device, called RotoJig, the rotation of the upper frame involves the complete fixture, plug and
In the new Cannon RotoJig polymerisation system the rotation of the upper frame involves the complete fixture, plug and lateral walls, and brings a newly foamed cabinet to polymerise in the "upper floor" of the plant.
Cannon Afros has been developing mixing heads and dosing units for Polyurethanes for nearly five decades. More than 30,000 mixing heads have been sold and most of them are still in production, connected with more than 13,000 metering units. The output range of these heads spans from 1 to 10,000 g/second, for a wide number of applications, chemical components, injection or pouring methods. Among the various fields of applications, the refrigerator and freezer industry stands out for Cannon as one of the most successful ones. Every innovation in the chemical side of this innovative sector of the industry is carefully analysed – sometimes years before it appears on the market – to make sure that the best processing tools are available when the new formulation will be released.
The evolution of the Cannon FPL and JL series are just one example of this ongoing commitment in the field of the reactive chemical's mixing technology. Recent important developments have been implemented by the major Raw Material Suppliers to improve thermal insulation properties and faster demoulding times for the domestic refrigerators and freezers made with their foams. Thermal insulation is greatly improved by reducing the average diameter of the foam's cells, and this can be obtained only with very fast-reacting formulations. As a consequence, since the refrigerators are becoming wider and larger, these fast foams must be injected at higher output rates than in the recent past. Japanese manufacturers have solved this problem by foaming their refrigerators with up to four mixing heads operating almost at the same time on the back of the same cabinet, using two dosing machines operating in fast sequence of injection. Other manufacturers have followed a different approach, working more on the mixing efficiency and on the total output of their mixing heads. Cannon has been working on two lines of development, destined to two different types of end users.
Cannon FPL SR – designed for existing refrigerator plants
Refrigerator manufacturers wishing to upgrade their current foaming plants in order to use fast-reacting foams – thus using higher output machines and mixing heads – are confronted with a basic problem: hundreds of existing moulds cannot be easily modified to accommodate the larger injection nozzles typical of higher output mixing heads. They are limited by the existing
geometries of their plugs, but they need to increase the components output avoiding the generation of more turbulence, which creates air entrapments and voids in the insulation layer. Cannon have designed the FPL SR, an evolution of their classic FPL head, that features an optimised design of the mixing area. The total output, with laminar flow at the nozzle, can reach 1,800 g/s with an injection nozzle of 24 mm of external diameter. In addition to this, the potential head's sticking problems created by modern high ISO Index formulations have been solved using a more efficient design of the self-cleaning plunger that provides a very efficient removal of the smallest traces of foam from the head's discharge duct.
Practical results in extended industrial runs have been very encouraging, and this head is now being manufactured in all the diameters required by the refrigerator makers running conventional foaming jigs and plants.
Cannon JL – the ideal choice for new plants
Designed without jets, the Cannon JL mixing head provides a unique opportunity to the refrigerator manufacturers investing in a new foaming plant. Their moulds and jigs can be freely designed to accommodate the longer and slightly larger nose of this head. This provides them a wide range of advantages: • Optimum mixing and very laminar injection at a very high output, in a range from 300 to 2,000 g/s, according to the head' size.
• Possibility to reach remote injection holes, thanks to the 200 mm injection nose.
• Possibility to vary the foam's output during the injection, in order to wet a very long portion of the refrigerator's back during the deposition of the foam. During the change of output the components pressure is reduced, but this is not anymore a problem for this head: the absence of injectors allows for this very wide range of outputs without influencing the mixing quality in a range of pressures going from 70 to 210 bar.
• Superior performances using low-boiling point blowing agents: the geometry of the JL avoids the “flash out” effect typical of many other heads.
The latest development of the Cannon FPL series, the SR model, is designed for the refrigerator manufacturers desiring to upgrade their existing foaming plants to the use of the modern, faster formulations.
More than 30 JL heads have been put in operation Worldwide at the major refrigerator manufacturers, that have already realised that these tools feature a very fast payback, even allowing for a certain saving in raw materials, and have not yet reached their limits in operation. A lot of improvements can be obtained in production, simply optimising the various components of the equipment and the design of their models. The same concept applies to other fields of application, like panel and pipe insulation, where these heads have started shoving all their advantages.
The Cannon JL 32, the latest model of this series, features a 200 mm long nose and is designed for the foam injection of the largest refrigerators.
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