GB2185958A - Apparatus for heat-shrinking sleeves onto articles - Google Patents

Abstract

Apparatus for heat-shrinking thermoplastic sleeves and the like onto articles, comprising conveyor means for moving the articles in a linear path; means for providing a supply of hot air; directing means for directing the hot air in a generally laminar flow so as to impinge laterally on articles to be sleeved moving on the conveyor means; and means for varying the cross-sectional profile of the laminar flow of air all along its length and also for varying the length of said path that the flow of air impinges on. In one embodiment, the directing means comprises a plurality of individually adjustable distributors each having a regulatable slot. In another embodiment, each of two opposed chambers has removable panel (15) having an air exit slot of desired profile to facilitate replacement by other panels having approximately profiled slots. <IMAGE>

Description

SPECIFICATION Heat shrinking apparatus This invention relates to apparatus for shrinking thermoplastic sleeves, tubular labels and other wrapping means onto articles such as bottles, canisters, cartons and other objects.

Heat-shrinkable thermoplastic sleeves are now well known as a packaging and labelling medium.

They generally comprise some form of PVC extrusion, but other thermoplastic compositions can be used. Although general heating of a sleeve of this type, while it is in position on the article to be sleeved, will cause shrinkage, this method is not easily controllable and produces distorted and uneven results. Forth is reason, it is found necessaryto supplythe heàt in an accurate controlled manner, generally by supplying a directed stream of hot air at the appropriate part of the surface for an appropriate length oftime. In sleeving vertical objects such as bottles, it is usually desirable to heatfirstthe bottom of the sleeve. Heat is then applied sequentiallyto areas of the sleeve above the originally shrunk portion, ending with the top of the sleeve.In this way, the zone of shrinkage is moved up the bottle in a controlled manner. This sequence of heating can be achieved by passing bottles on a conveyor past a hot air outlet in the form of a long slot inclined at an angle to the horizontal. Typical apparatus of this type is disclosed and claimed in British Patent No.

1,519,888. In this apparatus an air duct is supplied at each side ofthe conveyor having at its base an outlet slot of which end portions can be set at selected an gles to the main portion of the slot. The reasons for this is that it is often desired to provide an extra degree of heat at the top and the bottom of the sleeve and this can be achieved by arranging that the article to be sleeved passes, in succession, a lower horizontal portion of slot, a longer inclined portion of slot and an upper horizontal portion of slot.

The problem that arises with this type of apparatus is that it is difficultto control the temperature of the sleeve. Effectively, the slot is always of the same length, and thus the articles must always traverse this length of slot. Some articles and sleeves require less heat than others and those that need little heat can only be effectively sleeved by retracting the air ducts laterally and wasting a considerable proportion of the hot air.

We have now devised an apparatus in which the profile of the slot past which the articles move can be adjusted to give the desired heat gradient without waste of heat.

According to the present invention there is provided apparatus for heat shrinking thermoplastic sleeves and the like onto articles, comprising means for providing a supply of hot air; a plurality of individual distributorsforthe hot air, each including a substantially straight slot, the distributors being indi- vidually positionable so that the slots may be located in a substantially linear array in one substantially vertical plane, each slot being at any desired inclina tion, wherebythe slots may together effectively form an extended linear outlet of variable profile; duct means for the directing the hot air from the supply means to each distributor and conveyor means for moving articles to be sleeved past the slots.

Normally, the apparatus will be provided with two sets of distributors, one on either side of the conveyor, so that hot air is supplied to both sides ofthe articles at once. In a preferred embodiment, the duct means comprise a manifold providing individual streams of hot air to the distributors. The manifold conveniently comprises a longitudinal duct provided at longitudinally spaced intervals with branch ducts onto which the distributors are fitted. The dis tributors themselves conveniently comprise boxes of generally prismatic shape arranged for rotatable and slidable connection to the manifold. Each box is provided, preferably at one edge, with a slot. The slot is preferably adjustable, e.g. by having a movable plate whereby the width of the slot may be varied.

Advantageously the slot is adjustable to include a completely closed position. In this way, individual distributors at the end of the manifold can be shut down if a shorter slot profile is required for any one particular job.

All elements may be constructed of any suitable material, for example mild steel or lightweight alloys.

The manifold is conveniently mounted at an inclination to the horizontal, so as to provide the basic slot profile which is individually adjustable at each distributor. The angle of inclination may be adjustable by simple pivot means.

Hot air is conveniently provided by an electric fan and heater,which may, for preference, be controlled to give a variable degree of heat.

In use, the heater and the individual slots may be adjusted to provide an outlet air temperature of about 150"C, when using PVC sleeving. Under these conditions, a typical article can be sleeved in a pass of about 3 seconds, with a conveyor moving at about 30 cm/sec.

In order to illustrate the invention further, one embodimentwill now be described with reference to the accompanying drawings in which: Figure 1 represents a schematic side view of heat shrinking apparatus being used to heat shrink sleeves onto bottles; Figure2 is an end view of one distributorwith its mounting; and Figure 3 is a schematic end view of the apparatus shown in figure 1, showing only the first and last distributors.

Referring to figures 1 and 3,the apparatus com- prises on each side of a conveyor 1 an elongate duct 2 mounted at an incline to the conveyor 1, the angle of inclination being adjustable about a pivot 3. Each duct 2 is provided with an electrical heater 4 coupled via a flexible conduitS to an electric fan 6.

The duct 2 is arranged to distribute hot airvia tubes 7 to individual distributors 8, each provided with an adjustable slot 9.

Referring specifically to figure 2, each distributor8 comprises a prism shaped box 10 mounted for rotation on the end of a L-tube 11, itselftelescopically mounted on tube 7. The slot9 on each box 10 isadju- stable in width by means of a hingeable plate 12 which can be secured at any setting by a screw 13.

Rotation of the box 10aboutthe axis of the lower end of the L-tube 11 ailowsthe slot 9 to be placed at any required inclination. Telescopic sliding of the L-tube 11 on the tube 7 allows the relative height of the box 10 to be adjusted, while movement ofthe duct 2 aboutthe pivot 3 providesfurther adjustment. The slots can thus be aligned in any particular profile required.

In use, hot air is supplied by means ofthefan 6 and heater4 into the manifold duct2 and hence into each distributor 8. Bottles, or other articles, provided with heat-shrinkable PVC sleeves pass between the rows of distributors 8 by means of the conveyor 1,so that firstthe bottom and then subsequently higher regions ofthe sleeve are heated.

Heat may be controlled by having a variable power heater 4, typically providing up to 18 kilowatts.

It will be seen that the essence ofthe present in- vention lies in the provision of what amounts to a laminarsupplyofhotairto impingelaterallyonarticlesto be sleeved moving in a substantially straight path, the laminarsuppiy having a cross-section which is variable in profile all along its length and not just at each end, and also is variable in the length of said path itimpingeson.

In an alternative embodiment of the invention the plurality of individual distributors and duct means can be replaced buy a single distributor, generally one of an opposed pair, in the form of an elongate chamber or duct having interchangeable side panels, each including a slot of predetermined length and profile, but optionally of variable width.

Such an embodimentis illustrated in Figures 4 and 5 of the accompa nying drawings, in which The apparatus comprises on each side of a con veyorl,an elongate chamber 14providedwith an electric-heater4 coupled via a flexible conduit 5 to an electric fan 6 as before. Referring specifically to Figure 5, the chamber 14 comprises a generally rectangular box provided on the side facing inwards with a panel 15 which is arranged for removal and interchange with other panels 15 ofthe same size and shape. Each panel 15 is provided with and elongate slot 16 of a required profile or shape. Means may be provided on each panel 15 for adjustment of the width ofthe slot 16. By this arrangement, re- quired path length and profileofthelaminarhotair supply to the articles to be sleeved can be achieved by selecting the appropriate panel 15.

Claims (10)

1. Apparatus for heat-shrinking thermoplastic sleeves and the like onto articles, comprising conveyor means for moving the articles in a linear path; meansforproviding a supply of hot air; directing means for directing the hot air in a generally laminar flow so asto impinge laterally on articles to be sleeved moving on the conveyor means; and means for varying the cross-sectional profile the laminar flowofairall along its length and alsoforvarying the length of said path that the flow of air impinges on.

2. Apparatus according to claim 1, in which the directing means comprise a plurality of individual distributors for the hot air, each including a substantially straight slot, the distributors being individually positionable so that the slots may be located in a substantially linear array in one substantially vertical plane, each slot being at any desired inclination, wherebythe slots may together effectively form an extended linear outlet of variable profile, and duct means for directing the hot air from the supply means to each distributor.

3. Apparatus according to claim 2 comprising a longitudinally extending duct manifold communicating via branch ducts with the individual distributors.

4. Apparatus according to claim 2 or claim 3 in which each distributor comprises a generally prismshaped box having a slot at one edge.

5. Apparatus according to claim 4 in which each box is providedwith an adjustable plate whereby the width of the slot can be adjusted.

6. Apparatus according to claim 3 in which the duct manifold is pivotally mounted.

7. Apparatus according to claim 1, in which the directing means comprise an elongate chamber or duct having a removable side panel including a slot of predetermined length and profile.

8. Apparatus according to claim 7, in which the panel comprises means for adjusting the width of the slot.

9. Apparatus according to any of claims 1 to 5 in which the air is heated by an electric heater ofvariable heat output.

10. Apparatus for heat shrinking thermoplastic sleeves and the like substantially as described herein with reference to the accompanying drawings.