FR2499941A1 - APPARATUS FOR HOT RETRACTION OF THERMOPLASTIC SLEEVES AROUND CONTAINERS - Google Patents

Abstract

1. Apparatus for hot shrinking of thermoplastic sleeves around the surface of containers traveling on a conveyor comprising a tunnel (1) in which the conveyor (3) provided with the containers (4) passes and which tunnel is divided into three contiguous communicating zones, said zones consisting of a preheating zone or chamber (A), a shaping chamber (B) and a finishing chamber (C) ; the inferior part of the tunnel comprising a blower (7) drawing its delivery air from the preheating chamber (A) by a piping (9) ; the apparatus being characterized in that, on an expansion vessel (10) which is closed by a perforated plate (11) above the blower (7), are erected a series of flexible hollow tubes (12), at least most of said tubes having a nozzle (14) for blowing air there from ; said nozzles, which are orientable in all directions, being located in the shaping chamber (B) during the operation while at least one flexible tube (12') is connected to a diffuser (15), fixed or movable, located in the finishing chamber (C) and the pressurized output air from which constitutes a barrier forcing the hot air from the shaping chamber (B) to flow into the preheating chamber (A).

Description

The present invention relates to the field of

  production and circulation of hot air, intended in particular to

  causing the shrinkage or shrinkage of thermoformed plastic film

  retractable around a support such as a container to be dressed or decorated. It is particularly relevant to a new

  grooving intended for the operation of necking of duct sections or

  made of thermoplastic material around receptacles of shapes and natu-

re various.

  It is known that the use of sheaths or sleeves in heat-shrinkable plastic film, such as polyvinyl chloride or the like, for the decoration and / or the inviolability of containers of various shapes (bottles, aerosol cans, food boots, etc.) many problems in the retraction step. In fact, during the partial or total cladding of packaging, it is important to create zones where the temperature of the air is variable, for example increases gradually, so as to

  selectively cause the shrinkage of the sleeve on the various por-

  tions, of more or less complex conformation, of the container to be sheathed.

  Conventional shrink ovens for packaging films

  age for this purpose, attempts have been made to develop

  to advanced devices such as in particular: tunnel kilns with movable side walls requiring many organs and delicate adjustments (US Patent No. 3,808,702); an air recirculating oven and adjustable deflectors for obtaining progressively hot air in different areas of the sleeve, but the use of which is limited to low-height receptacles (French patent N075.24467, publication N 2320 517) ; adjustable diffuser housings in all directions, provided at their base with a longitudinal hot air distribution slot

  with discontinuities in direction, for example by means of

  articulated reentrants, such a casing being disposed on each side

  a conveyor where the sleeved containers circulate, ready to be

  treints (main French patent No. 5.30896 and its additions

N075.36299, 76.08851, and 76.39546).

  The invention aims to further improve the shrink sleeve systems to make them suitable for the processing of all types of receptacles and to avoid the presence of folds in areas of high discontinuity of certain packaging. It also aims to develop a device that maximizes the savings of calories burned for retraction and allows universal use.

  for any type of packaging.

  To achieve these goals and others that will appear

  during the present description, the invention proposes a new

  which essentially comprises: a) a tunnel in which the container conveyor circulates and divided into three contiguous zones communicating with each other, including a zone or preheating chamber, a chamber for

  actual trephine and a finishing chamber; (b) a ventilation fan

  by the air in the chamber, and on its exit from

  flow, an expansion vessel closed by a perforated plate on which

  are connected series of flexible hollow tubes receiving, for the most part an air blowing nozzle; said nozzles, adjustable in all directions, being in operation in the necking chamber while at least one flexible tube is connected to a diffuser located at the level of the finishing chamber and whose outlet air, under slight pressure, constitutes a barrier forcing hot air

  the necking chamber to flow to the preheating chamber.

  In practice, the width adopted for the tunnel is

  generally that which corresponds substantially to the. width of the conveyor.

  The walls of the tunnel are insulated thermally, for example by glass wool or equivalent heat insulated introduced between two plates of

tale.

  Communication between the zones or rooms specified

  The interior of the tunnel is essentially made by the passage left free for the circulation of the containers on the conveyor. So that each zone performs its function correctly without equalization

  temperatures, it is advantageous to provide the upper walls with

  front and side of the baffle tunnel acting as separators

  zones whose opening corresponds to said free passage of the containers.

  The heating of the air for the operation of

  traction sleeves can be provided by any known means. For example, according to one embodiment, each nozzle is provided in the sleeve which supports it with electric finned resistors.According to another embodiment, the electrical resistors can be mounted in the

  housing or expansion vessel that surmounts the fan.

  The invention will be better understood and other details

  will be apparent from the description which follows, relating to a mode of execution

  nonlimiting example illustrated by the accompanying drawings which show schematic

cally

  Figure I: a sectional view, in profile, of a retraction device

  thermoplastic film-according to the invention;

  Figure 2: a plan view, 90 degrees from Figure I; -

  Figure 3: the detail of a perforated plate adaptable to the expansion tank of the fan;

  Figure 4: a detail of embodiment of nozzle.

  As represented in simplified form in FIG.

  a device according to the invention essentially comprises: an oven-tun-

  1, divided into three zones A, B, C and a set 2 for the suction

  blowing and blowing hot air and equipped with an original system of dis-

  tribution of the air for the heat shrink of sleeves on recep-

tackling.

  The tunnel I is made of insulated sheet metal walls 2 (by glass wool or the like) and adapts substantially to the dimensions

  a conventional conveyor 3 of sleeved containers 4 which passes through the tunnel.

  along a continuous path 5 first through the preheating chamber

  A, then the narrowing or retraction chamber B and the

  C. Each chamber or zone is separated by baffles 6 which

  substantially reduce the free space provided for the circulation of

pients 4.

  In accordance with an originality of the invention, the ventilation

  7, m. by the motor 8, sucks its air directly through the pipe 9 into the preheating chamber A. In addition, this fan is surmounted by a hollow box 10 or expansion vessel closed by a perforated plate

  In the holes of which are mounted flexible tubes 12. The

  perforation 13 of the plate II (see FIG. 3) can be well

  any tense, for example six, eight, ten or more. Most of the hoses 12 support at their end a nozzle 14 with pinched edges which

  delivers a thin air gap corresponding to the width of the split slot.

  lectionnée. These series of nozzles 14 surround the sleeved container 4 (see FIG. 2) which circulates in the tunnel at the level of the chamber B where retraction of the sleeve is carried out by suitable orientation and

  very flexible air blades from adjustable nozzles.

  According to an advantageous embodiment, at least one flexible

  12 'is connected to a fixed or movable diffuser 15 placed in the chamber.

  C. The pressurized air coming from this diffuser plays the

  role of barrier to the exit of hot air from the room

  B constraint and forces it to be pushed in the direction of the arrow 16 on the side of the preheating chamber A. In this way there is no heat or heat loss outside the tunnel and the air warm room A, instead of escaping into the atmosphere is

  recovered directly by the fan 7.

  The additional heating of this warm air

  can be obtained by any known means. Thus one can adapt

  in the mandrel 17 which supports the nozzle 14. According to one variant, such resistors can be installed in the

  housing 10 which overcomes the fan 7.

  Of course, the lid or cap 18 of the tunnel I is preferably mounted removably to be able to intervene,

  if necessary, during narrowing operations and allow opening

  automatically when the Conveyor stops, thus avoiding over-

  heats products inside the tunnel.

  In addition to the aforementioned advantages of the device according to

  the invention it should be pointed out that the temperature regulation is

  killed by simple spacing of the nozzles relative to the sleeved container; in addition, this temperature can be regulated by thermostat at the level

  aforementioned electrical resistors.

R E V E N D I CATI 0 N S

  1. Apparatus for the hot shrinkage of thermoplastic sleeves around containers circulating on a conveyor, characterized in that it comprises: a) a tunnel (1) in which the conveyor (3) with containers (4) and divided into three contiguous zones communicating with each other including a zone or preheating chamber (A), a necking chamber (B) and a finishing chamber (C); b) a fan (7) supplied with air from the preheating chamber (A) to its discharge outlet (9) and provided with a closed expansion vessel (10)

  by a perforated plate (11) on which are connected series of tu-

  flexible recesses (12) receiving for the most part a nozzle (14) for

  air flow; said nozzles, which can be rotated in all directions, are

  during operation in the necking chamber (B) while

  least one flexible tube (12) is connected to a diffuser (15), fixed or movable

  the, located at the level of the finishing chamber (C) and whose pressurized outlet air is a barrier forcing the hot air of the chamber of

  shrinks (B) to flow to the preheating chamber (A).

  2. Apparatus according to claim 1, characterized in that the tunnel (I), whose side walls (2) are insulated and the cover 18 removable, is provided with baffles (6) to close the maximum contours of space free for the circulation of containers (4) on the conveyor (3)

  Apparatus according to any of the claims

  I or 2, characterized in that each nozzle (14) is provided with resistance

these heaters (17).

  4. Apparatus according to any one of the claims

  I or 2, characterized in that the housing or expansion vessel (10) of

  fan (7) is provided with heating elements.