VERTICAL OVEN PLASTIC VACUUM FORMING MACHINE

MACHINE A FORMER SOUS VIDE DES FOURS VERTICAUX

English Abstract

A vertical forming machine using ambient temperature and fired by low cost
natural
gas, propane, etc. built to shape difficult, dissimilar materials. The machine
will
laminate arrangements of shaped materials easily. Example: Foam plastic
laminated
to rigid plastic. The vertical arrangement will allow for twin sheet forming
with minimal
setup.
Rapidly moving air will heat the plastic material and dual air-flow system
allows for
faster production with materials being formed heated evenly throughout sheet.
Shaping of sheet plastic is accomplished with a unique vertical mould system
complete with controlled advance and all forming taking place inside a narrow
air
stream, centrally positioned inside oven.
Doors in front and back of oven open and close to permit access of forming
moulds.
Door also at both ends of oven to permit entry of sheet and exit of forming.
Uneven
heating or over-heating of sheet is eliminated when using this vertical
controlled-heat
oven.

Claims

CLAIMS
CLAIM 1: Narrow vertical oven consisting of counter-balanced doors both front
and
back for mould access, and two ends allowing material to access and finished
product to exit, and a curtain of heated air where plastic is heated and
formed.
CLAIM 2: Dual system of moving air in oven consisting of regular oven air
circulation
up to required forming temperature and an air curtain of rapidly moving air
which can
be separated from main flow, during forming and cooling of plastic.
CLAIM 3: Moulds capable of entering oven from two sides front and back,
consisting
of a structure wherein moulds are moved into the soft plastic from one or two
sides
and are guided into forming position where they may be locked into position
while
extreme pressure is applied to shape and to detail the sheet plastic.
CLAIM 4: Fixed frame in oven consisting of four sides adjustable to different
sizes.
No four-sided clamps on frame are required. Moulds will clamp plastic to this
frame
and vacuum channel (figure'A') will help ensure proper vacuum seal for mould
on
plastic so that vacuum can shape plastic. This fixed frame can be arranged to
hold
reinforcing frames that can be incorporated in twin sheet or single sheet
forming.
NOTE: The vacuum channel in mould is important in large forming where plastic
shrinkage is a problem, due to vacuum seal leakage.
CLAIM 5: Laminating of material in vertical oven consisting of a fixed frame
wherein
different materials are hung in oven to heat then pressed together to
eliminate air and
to finally form into female mould using vacuum and pressure.
CLAIM 6: Straight through production consisting of a preheat oven holding
multiple
sheets arranged to be fed into narrow oven through end door in the narrow
oven, and
processed with minimal heat-time.
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Description

CA 02545440 2006-05-03
SPECIFICATION
In most production using thermoplastic sheet the plastic is heated
horizontally and is
clamped firmly on four-sides with moulds entering from bottom and top in a
special
forming area (not the actual heated oven). In order to reach this forming and
cooling
position the plastic must be moved, losing heat and time in the moving.
Radiant heat elements are used to heat the sheet evenly and rapidly to the
core.
Since radiant heat only heats the surface and slowly works its way through the
sheet,
the slowness of heat-speed through the sheet causes a problem when using
radiant
heat (in that the surface of plastic can get over-heated easily). Sag of sheet
during
heating occurs and presents a major problem when shaping in large flat areas.
Whereas, a vertical sheet is always presented to the forming area as flat.
Production losses can also happen when uneven heat or overheating occurs in
the
sheet due to poor sheet materials, varying thicknesses, sheet-sagging, etc.
Polycarbonate plastic has to be dried before forming in order to eliminate
moisture
bubbles that occur when heating and the cooling process is very fast.
Polycarbonate
can now be processed in our vertical oven without drying, because the moisture
is
eliminated slowly, and forming can take place within the heated air stream.
This
procedure of forming in heat eliminates the fast-cooling problem occurring
during
transferring plastic from oven to forming area.
In addition, our system of heating with ambient air temperature, allows
plastic to soak
in the heat at forming temperature, with no spoilage due to uneven or
overheating of
the material being formed.
This superior system of heating and forming, allows for heating a wide variety
of
dissimilar materials such as plastic, foam, rubber, wood, foam insulation,
etc. Not
possible with regular system.
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CA 02545440 2006-05-03
Furthermore, over-heating of the plastic sheets are reduced and consequently,
spoilage is reduced. Ability in this machine to combine the plastics in a
"laminated
arrangement" allows engineering to use materials together for strength
insulation
appearance etc. Structures of metal wood can also be easily combined in this
vertical
machine.
DESCRIPTION
Very narrow oven (figure) to hold vertical sheets and to heat uniformly one
sheet of
plastic (figure2) for standard forming or two sheets for twin sheet production
which
can double the speed of production since two sheets can be shaped at one time
using female moulds.
Heater (figure3) will heat air in the oven to production temperature. Blowers
(figure'o)
will circulate heated air passing through main oven and motors (figure12),
will ultra-
rapidly circulate through the forming cooling section of oven. Forming and
cooling
area may be isolated from general oven by closing top shut off (figure13) and
bottom
shut off (figure14). Eliminating ultra-rapid air-curtain, and allowing two
separate
systems of air circulation, regular oven and air-curtain. The two systems
speed up
the time required to heat sheets to process temperature, by saving heated air
stored
in regular oven.
Counter-balanced doors (figure") front and back (figure5) will be opened and
closed
by a motor (figure1) allowing female mould (figure6) and male mould to proceed
forward into soft plastic sheet (figure') and with pressure applied on plastic
and the
application or vacuum on mould and vacuum in a sealing channel around
perimeter
of mould to hold plastic tightly to mould until cooled.
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CA 02545440 2006-05-03
Forming of plastic takes place inside narrow oven and plastic may be easily
loaded
from front of machine or loaded from end of machine, unload of finished part
can be
from front or out opposite end of machine.
This machine is designed for using low cost energy such as gas or propane.
However heating of plastic can be speeded up by installing radiant energy
electric
heaters in door panels front or back. Control of this radiant energy in zones
can also
adjust heat over surface of plastic.
The vertical configuration of forming allows the operator to soak the plastic
in the
forming temperature for more even heat subsequently better forming less
spoilage.
Inside the vertical machine centrally located in the middle of the narrow
plastic
heating air stream is a non-moving but adjustable fixed frame (figure8). This
frame
allows clamping of plastic and with the addition of proper jigs, the ability
to position
reinforcing structures (wood, metal, plastic) to be built into product with
plastic sheet
finish applied on one or two sides. Example: pontoons, tanks, airplane wings,
etc.).
This vertical machine forming in oven is an advanced tool for the plastic
sheet
processor. With built-in versatility and superior performance when handling
large
formings, and the machine is capable of laminating dissimilar materials before
moulding into products.
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Representative Drawing