Refrigerated trucks dedicated foaming solutions for extra-large by yaofenji


									              Refrigerated trucks: dedicated foaming solutions
                      for extra-large insulated panels.
                         by Max Taverna - Corporate Director Communications & IT - Cannon Goup - Italy

Large insulated panels are increasingly                               and space occupancy, in order to preserve the
needed for manufacturing huge insulated                               maximum truck's volume and net tonnage for the
trucks. A variety of insulating media can be                          main purpose of the business: transporting more
used for this demanding application, and                              goods with less fuel!
Polyurethanes provide the most flexible
solution. Automating the production of these                          Polyurethane foam proved, among other viable
large elements constitutes a challenging task.                        alternatives, to be the most efficient insulation
Cannon have matured significant experiences                           media also for this application. Its specific density is
in the past ten years in this field. One of the                       lower than that of mineral or glass wool, its method
latest achievements is a complete plant for                           of application expanding in situ is more flexible
the production of 13.6m long, 2.7m wide                               than that of other expanded synthetic foams, and
panels, installed last year in                                                               most important - its insulating
the new factory of a German                                                                  capacity is better than that of
leader of this field who                                                                     all other competitors!
makes two complete trucks
per hour. High-pressure                                                                      For these and other very good
high-output metering                                                                         reasons the use of rigid
equipment, large                                                                             Polyurethane as insulation
polymerisation presses,                                                                      media is going well beyond
impressive panel-handling                                                                    the basic “cold chain”
systems are illustrated in                                                                   application for food transport.
this paper, to witness the                                                                   Rigid walls provide a safer
size of this challenging                                                                     solution than the old-
project executed by the                                                                      fashioned canvas-covered
Cannon Group.                                                                                boxes, both in terms of anti-
                                                                                             theft and anti-fall aspects.
The market                                                                                   Cutting with a knife the textile
The transportation of goods from                                                             cover of trucks during the
the point of manufacture to the                                                               driver's lunch break
point of sale is increasingly done                                                                constitutes the preferred
“on rubber wheels”, i.e. by truck                                                                 sport for many road-
but… gone are the times when a                                                                    warriors in several
truck was either “a box” or “ a                                                                   countries, especially now
tanker”! Visiting the website of a                                                                that once-difficult-to-cross
major truck manufacturer one                                                                      borders have been
can find at leas thirty different                                                                 infringed and road
versions of commercial vehicle,                                                                   transports cover extremely
each of them covering a                                                                       wide distances in Europe,
specialized mode of                                                                           Middle East and South
transportation to ensure the                                                                  America. A rigid wall, made
highest efficiency in this very                                                               with a metal or GRP sandwich
sophisticated field of human                                                                  filled with a few centimeters
activity: logistics. Modern trucks                                                            of Polyurethane, constitutes a
are very expensive, but, today more than in the                       much tougher obstacle for the occasional burglar,
past, give very good value for money: exploiting the                  improving security and lowering insurance costs.
latest developments in every aspect of their                          Unstable loads or sharp objects often hit, on sharp
construction - engine efficiency, safety and comfort                  bends or sudden breaks, the interior walls of a
for the driver, security and proper storage for the                   truck, and many times they break the canvas or
transported goods they guarantee fast return on                       plastic covers that hide them in the boxes.
the investment and quick service to the customer.                     This causes visible damage to the cover and
                                                                      potential hazard for those who are passing nearby.
Refrigerated transportation constitutes a major field                 A rigid wall would absorb most of the hit, providing
of activity in this domain, providing the key ring in                 safety and avoiding permanent damage to the sides
the “cold chain” that brings fresh food on our tables                 of the box.
daily. To be efficient it must guarantee the highest                  An insulated sandwich also provides a certain
insulation capacity with the lowest possible weigh                    degree of thermal insulation against the direct
sunlight, even without using a refrigerator pack         In strict synergy with Krone, Brüggen developed the
that remains a compulsory component of a real            refrigerated line of trucks called Fresh Liner, made
refrigerated transport. Delicate items - such as non     of sandwich panels 28-30 mm thick having a PUR-
perishable foods and drinks, cosmetics, medicines,       hard foam core and a shock-resistant metallic top
some electronic devices, green plants, low-boiling-      coating. These characteristics provide a high
point solvents and chemicals - can be transported        insulation property and the best resistance to aging.
more safely in hot areas if insulated trucks are used,   The chassis of the Fresh Liner has all the qualities of
avoiding deterioration from excessive heath.             the Krone program: durability, low maintenance
Therefore the demand for Polyurethane-insulated          costs and long-term rust protection due to powder-
panels for trucks is growing in almost every             coated E-coating.
                                                         The needs
The Client                                               The success of the Fresh Liner series and Krone'
Metal Service Brüggen Ltd. was founded in 1990 by        stubbornly-pursued target of becoming the World's
Bernard Brüggen. Starting their activity - the           number one supplier of swap bodies, convinced
manufacture of truck's beds and boxes - with thirty      Bernard Brüggen to further expand their fast-
employees in Herzlake, Germany, the company very         growing company, deciding in the year 2005 the
soon found an interesting cooperation with the           investment of several million Euros in a brand new
Wertle-based trailer manufacturer Krone. Two years       factory in Lübtheen, between Hamburg and Berlin.
later there were seventy employees and - at the
cost of a very intense personal work - the company       Fully foreseen for the production of refrigerated and
gradually achieved its breakthrough.                     insulated trucks, this modern production unit has a
As Krone downsized internal production of some of        very ambitious target: to roll out one complete
their components, these were outsourced to               Swap-Body every thirty minutes! Completely
Brüggen. Soon the complete manufacturing of              mounted and finished, possibly made-on-request,
Swap-Bodies (closed boxes) and flat bed                  i.e. fully assembled upon a specific customer's list of
construction was outsourced to Metal Service             accessories and finishing options.
Brüggen, which soon also took over the
manufacturing of spare parts for Krone vehicles.         The task was demanding, the suppliers had to be
Their production range is today quite sizeable.          selected accordingly. Several qualified plant
The production includes the line of Swap-Bodies for      suppliers in the field were investigated, and Cannon
trucks and rail. There are as well closed boxes with     was among them. The basic demand was simple:
side and rear doors and platforms in the rear as an      this is the ground - a wheat field, actually - you let
open version or with side or rear walls as well as       us know what we should build on it to make two
those with side flaps.                                   insulated boxes per hour. Period.

Many of the single parts are manufactured in the         Sometimes the most demanding jobs have a very
company itself. Brüggen is active in different areas     simple start…
for German and European car manufacturers.
For example, complete bodies of busses are dip           The solution
coated and partly assembled in their factory.            Cannon was ready to face the challenge, thanks to a
The development of new technologies was                  long-standing tradition of large plants for all the
approached with great emphasis: for instance the         applications of thermal insulation components:
plain wall for closed boxes was developed for            refrigerators, cold rooms, walk-in coolers, plus of
production since the year 2000. As compared to the       course a very important reference in the production
box with corrugated walls, that meant a tremendous       of insulated containers the “reefers” made by
financial advantage for the user.                        Maersk in Denmark for several years with a huge
                                                         Cannon turn-key plant.

                                                         To make a long story short, an innovative solution
                                                         was designed and submitted to the Brüggen
                                                         company. It included the supply of the core of the
                                                         system (chemical bulk storage, foaming machines,
                                                         polymerisation presses) plus the design of a
                                                         complete layout for the new factory a vast unique
                                                         building covering almost 20,000 sqm and the
                                                         specifications for another fundamental components
                                                         of the assembly line: the metal forming plant.

                                                         A substantial contribution to the product
                                                         engineering was also offered, in order to optimize
                                                         the manufacturing process.
All the alternatives were evaluated, the usual battle
was fought between buyers and potential sellers,
and Cannon won the multi-million Euro order.
It is interesting to understand why, since the quoted
price was not the major deciding factor, but let us
have a look at the proposed solution first.

The supply
A refrigerated Swap-Body is made assembling
individual insulated panels of different thickness and
composition.                                                                                    The chemical’s premixing station
What is generally fixed for this project is the
dimension of the box: 13.6 m length by 2.5 m width                    safe and automated handling.
by 2.7 m height. Thickness of the panels vary,                        From here the two Polyols are transferred on
according to the models, from 4 to 8 cm for the side                  demand to the premixing station where, using two
panels, 8-10 cm for the roof and about 15-20 cm for                   Penta EasyFroth 40 units, they are precisely blended
the floor. Facings are constituted by pre-painted flat                with the required percentage of hydrocarbonic
steel sheets in most of the cases, but may include                    blowing agent (a Pentane grade) and sent to the
aluminum sheets and gel-coated GRP foils.                             two 2,000 liters day tanks backing the PUR dosing
                                                                      machines, located on a mezzanine in the production
                                                                      hall. A preblending unit for the addition of one
                                                                      catalyst is also installed in this formulation's room,
                                                                      to allow for fine tuning of the foam's reaction profile
                                                                      in case of special needs.

                                                                      Metering and mixing
                                                                      Cannon Afros has provided the metering and mixing
                                                                      equipment. High pressure technology was a must
                                                                      for a few good reasons: automatic foaming
    Standard (13.5 m) and extra-long refrigerated "Swap-Bodies" are   processes do not allow for periodic head's solvent
       produced with the new plant supplied by Cannon in Germany      cleaning, without mentioning the potentially
                                                                      negative impact of the cleaning liquids on the
One press was required for each side panel, one for                   working environment. High output high pressure
the roof, one for the floor and one for the squared                   machines were constructed, to allow for the delivery
front and the large rear doors. Always looking for                    of large shots in a reduced time. Special execution
further evolutions of the market, Brüggen had                         was demanded by the potentially explosive blowing
specified the possibility of producing also longer                    agent used in these formulations.
panels: if and when European circulation rules will
allow for it, then it would be important for them to
have manufacturing capacity for 16 m long trailers.
In Northern Europe’s countries a 15.5 m long trailer
is allowed on the road.
For this reason part of the polymerisation presses
were specified for this future extra-long production,
while keeping of course the target of making 13.6 m
long panels in them. An extra effort was done,
specifying another press for a Jumbo panel's size:
up to 18 m! Good now for making in one run two
panels for “short” versions of trucks with 7.15 m
chassis. And in future… who knows?
The supplied Cannon solution includes components
made by three different Units of the Group, which                                                     One of the large dosing units
were coordinated by a Project Manager of one of
the Cannon companies.                                                 Two large A-System 350 Penta Twin machines were
                                                                      supplied for sidewalls and roof panels, while two A-
Chemicals storage                                                     System 200 Penta Twin were destined to the floor
Bono Sistemi has supplied the chemical's bulk                         and the front ends plus doors.
storage: four 30 m3 tanks for two different Polyols,                  Foaming needs are different, according to the type
three 30 m3 tanks for the Isocyanate, one 45 m3                       of panels: side walls and roofs demand for an open
underground tank for the blowing agent (Pentane).                     pouring technique, while front and rear panels
Unloaded from the road tankers, the components                        must be injected in closed mould. The floor - due to
are stored in these large reservoirs which are fitted                 different design alternatives - might need either
with the most modern accessories to ensure their                      open mould pouring or closed mould injection.
In both cases, the chemistry of this system requires
a very high instant output and extremely efficient
mixing heads, able to pour the liquid blend without
major splashing at the high output required.
Considering a panel size of 13.6 m x 2.7 m x 0.1 m
and an expected foam density of 50 kg/m3, the
resulting shot size is in the order of 180-200 kg of
liquid to be dispensed and properly mixed in less
than 20-30 seconds. Quite a job…

The Cannon FPL mixing heads mounted in this plant:
large FPL 32 for the foam injection, small FPL 10 for the distribution
of an adhesion promoter.

The choice went for eight of the largest size of the
well-known L-shaped Cannon mixhead, the FPL 32,
for the open mould operation. Two of these large                                                           The dedicated head-holders.
heads are firmly inserted into the opposing ends of
a large plastic pipe, hollow in its lower side.                            The result is a very regular distribution of foam
When the lower platen - containing the bottom                              densities and a possible saving in raw material, due
facing of a panel - is sliding into the polymerisation                     to the lack of foam's overpacking. The hollow pipe is
press at the speed of 1 meter per second, the foam                         automatically released at the end of the pouring
injection starts from both heads fed by the two                            operation, and drops in a waste container positioned
dosing units which operate simultaneously,                                 underneath.
controlled by the central PLC.                                             The mixing heads are of self-cleaning type and do
The hollow plastic pipe is quickly filled with liquid,                     not require further maintenance operations till the
which can only exit through the evenly-distributed                         next shot. Another plastic pipe is manually
holes drilled on its bottom and therefore is uniformly                     positioned on the pipe-holder fixed as a bridge in
distributed across the whole width of the panel.                           front of the press short side, and the machine is
Since the foaming operation is precisely                                   ready for the next operation.
synchronized with the entry of the lower platen in                         Four FPL 24 heads were chosen for the robotized
the press and stops as soon as this has finished its                       injections to be performed in closed cavity, in the
run, the liquid is also laid down precisely and evenly                     two presses where the floor panels and the front
on the whole length of the panel. This ensures                             ends plus doors of the box are produced.
maximum homogeneity and even distribution of the                           Characterized by a compact size and with a reduced
foam across the whole surface and avoids the need                          nozzle's diameter they can be inserted in the side of
for the foam to “run” to fill the corners.                                 the thinnest panels without geometry problems.
                                                                           The two-axes head manipulators carry the mixing
The open-mould pouring technology used to perfectly distribute             devices in front of the injection holes, set and
the foam inside the panels utilises a disposable hollow plastic pipe fed
                                                                           memorized at preprogrammed positions on the
by two large FPL 32 mixheads.
                                                                           length of each model. Injections are made in
                                                                           sequence, with automatic plugs closing the injection
                                                                           holes immediately after each foaming shot.
                                                                           This allows for the perfect filling of the cavities that
                                                                           are created within the panels by the reinforcing
                                                                           wood partitions fixed on the plywood sheets pre-
                                                                           assembled in the panel: if the foaming was
                                                                           performed in only one or two holes these wood bars
                                                                           would obstacle the optimum filling of the panel,
                                                                           leaving air voids in it.
Simply positioning the injection holes between             This high level of specifications in terms of
them, on the whole panel length, the perfect filling       mechanical and electronic components is designed
is guaranteed.                                             to ensure long-lasting equipment in a completely
It is interesting to notice that the press for the floor   automated process. Cheaper solutions would have
panels is designed for both open-mould pouring             been more interesting money-wise but would have
(with the hollow pipe) and closed mould injection,         not be recommendable on the long run.
for maximum production flexibility in case of models
featuring a complex design.                                Polymerisation presses
For future possible utilization, the application of a      The visually most impressive impact of this huge
special adhesion promoter a sort of “glue” able to         plant comes from the five polymerisation units
increase the surface adhesion between PUR foam             supplied by Manni, the Mantua-based panel press
and metal sheets was required. Therefore two               specialists working for almost twenty years in tight
smaller dosing units were added to the larger ones:        co-operation with the Cannon Group.
two A-Compact 20 FC, each connected to three FPL
10 mixheads, with a piping circuit that precisely          Well known for their highly productive
follows the path of the main component's one, up to        manufacturing systems, Manni have in this case
the three “2+2” presses. Here a pipe-holding               supplied
system for a plastic pipe of much smaller diameter         · one large unit (16 m long, 2.8 m wide)
is mounted in parallel to the main one. In case of           of their “2+2” version for floor panels
need it will be used to pre-laydown a small quantity       · three units of the “2+0.5” version, two in
of this adhesion-promoting formulation just before           16 m x 3.4 m execution and an extra long one
the laydown of the insulation foam.                          (18 m x 3.4 m)
The A-System 350 Penta Twin dosing machines                · one smaller “2+2” press (3.5 m x 3.5 m platens)
feature four 107cm3/rev Rexroth pumps, to                    for the front ends and doors.
guarantee maximum precision and constancy of
flow for the rather long injections, which are             In the “2+2” version the preparation of panels - the
performed at very high output.                             positioning of the metal facings in the lower trays -
The very same brand of pumps - of smaller models,          is carried out automatically by pneumatic aerial
though - equips the other dosing units.                    manipulators. While two trays are being serviced
All process parameters - component temperatures,           outside the opposite ends of the press, the other
pressure, output and ratio - are monitored with            two are closed in the polymerisation press where
high-accuracy sensors on the high pressure line,           the foam is curing. When these are ready for
and recorded with a Cannon OVS electronic control.         demoulding they slide out from the press and
A Siemens Simatic S7 PLC takes care of the whole           simultaneously the other two trays ready to be
operating sequence and relevant safeties on each           injected - follow them into the empty cavities.
                                                                                An internal view of a polymerisation press.
In the “2+0.5” version while one tray is being
serviced the other is closed in the polymerisation
press where the foam is curing. After the extraction
of a finished panel an extra upper platen located in
the rear of the press carries in it the heated upper
metal sheet. Duly fixed to the upper side of the
press by means of vacuum suckers, this upper
facing is clamped by the rising lower tray when the
open-mould pouring operation has been finished
and the tray has reached the end point of its run.
The availability of this extra “+0.5” portion of
equipment saves the pre-heating time (which is
done off-cycle) from the total cycle time.
                                                                                                                     A finished, large panel.

                                                                           The presses hold the panels for a curing time which
                                                                           can vary from 20 and 60 minutes, according to the
                                                                           thickness of the foamed part, and unload them on
                                                                           the same side from which the relevant lower platen
                                                                           had been previously loaded.
                                                                           A series of large aerial pneumatic handlers carries
                                                                           the finished panels to the common unloading
                                                                           conveyor, and from here they are sent to the
                                                                           assembly hall.

The dedicated press used for the doors and the front ends.

An important feature common to all these five
polymerisation units is the high speed of translation
that can be achieved during the open-mould
foaming operation: up to one meter per second
speed is a must, in order to perform the complete
foaming phase well before the foam starts rising
something that must absolutely happen only when
the press is well closed!

The mechanical execution of the presses had to be
conceived in a very robust way, in order to
guarantee a long lasting equipment which is at the
same time fast and precise, with such an important
mass of metal in movement!
This fast speed of translation, combined with a
mixing head able to keep pace with the deriving
very high instant output of the two chemical
components, proved to be one of the winning
factors for Cannon.

                   A bird’s view of the plant, from the demoulding area.

                                                                                             A detail of the overhead panel handling system.

                                                                           Here they are set in position by large mechanical
                                                                           handlers, and manually screwed together and fitted
                                                                           with all the necessary ancillary toolings: hinges,
                                                                           lights, mechanical parts etc.
                                                                           An interesting detail of these high-quality boxes has
                                                                           a deep influence on the foaming operations: the
                                                                           lateral rails with holes that are used to hold any kind
                                                                           of hook or fixing device.
These rails allow for an easy and safe partition of                       Conclusions
the box vertically and horizontally, for instance to                      Cannon experience in the final product's field was a
make a double decker for optimum exploitation of                          “plus” in this phase of the negotiation, and clearly
the volume when transporting light loads. Since the                       contributed to the success in getting this important
most constraining dimension in a truck is the width                       contract.
which cannot exceed 2.55 m outside it is of                               Another good reason for choosing the Cannon
paramount importance to use thin walls (35-40 mm                          solution was the availability of robust, high-speed
foam thickness is the classic one) to exploit the                         press-feeding equipment, able to keep the pace of
maximum internal space: two standard 1.2 m wide                           large dosing machines using splash-free mixing
pallets must be easily accommodated sidewise on                           heads at a very high output.
the floor, therefore any tooling fixed on the internal                    As all the negotiation was made in Germany, the
walls would steel part of this space. Krone's                             presence of a strong local Cannon Unit in the
insulated boxes are designed with lateral tool-                           country was another winning factor: following the
supporting rails built “flush deck”, i.e. completely                      strategy of providing a qualified local presence - not
inserted inside the wall panel: only the face of the                      only with commercial people but mainly with
rail with its holes is visible.                                           technical experts knowing what the local market
                                                                          and mentality requires - also in this case Cannon
                                                                          have been able to win an important contract in a
                                                                          country where its strongest competitors were born
                                                                          and are well appreciated.

A detail of the truck’s interior, with the built-in partitioning rails.   The new factory built to accommodate the new foaming plant.

This solution creates some problems to the                                This complex project is the summary of many
assembly phase of the panels: all these robust                            different solutions, each of whom requires dedicated
metal rails must be fixed into the interior face of the                   expertise and skills: the availability of Cannon
panel, by carving first the proper holes in the metal                     dedicated Units able to express their best results in
sheet and fixing the rails precisely in them prior to                     fields as different as
foaming. All this had to be considered in the design                      · the management of chemical fluids,
of the pre-assembly area and in the conception of                         · the Polyurethane foaming technology,
the foaming method. All these and other panel-                            · the construction of large mechanical engineering
related details - such as for instance the best                              for handling of huge foamed parts,
methods for joining the different panels, which has                       · the numeric control of process and
an influence on their design and relevant                                 · the capacity to handle the management of
manufacturing method - were discussed between                                complex industrial projects
Brüggen's management and Cannon specialists prior                         provided the required safety to a customer that at
to the specification of the final equipment, in order                     the beginning of his project showed some 50,000
to provide the most adapt solution to the highly-                         msq of wheat fields and simply said: “let me make
specified product demanded by Krone.                                      two Swap Bodies per hour in this place!”

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