TECHNICAL FIELD This invention is concerned with improvements in or relating to apparatus for use in the treatment of wor pieces wherein jets of air are directed through nozzles on to each workpiece surface to be treated, said apparatus comprising a first chamber which constitutes a plenum chamber, a fan having an impeller by which air is impelled into the first chamber, a second chamber having one or more wall portions in which the nozzles are arranged, whereby air impelled into the first chamber is directed through the nozzles into the second chamber, and workpiece supporting and advancing means for supporting workpieces each with the surface thereof to be treated exposed and for advancing said workpieces through the second chamber along a path past the nozzles, wherein air is drawn from the second chamber , and thus from the vicinity of the workpiece supporting and advancing means, by means of the fan. BACKGROUND ART

One such apparatus, which is for use in the heat setting of shoes, is described in GB-A-2,088,195. Another such apparatus for use in drying adhesive coatings applied to shoes and/or shoe components, is described in EP-A-0,328,923. Moreover, other apparatus for effecting a similar adhesive coating drying operation are described in EP-A-0,512,772.

In each of the aforementioned apparatus, the fan is accommodated in a scroll, which thus constitutes the first chamber. Such scrolls are, however, expensive to manufacture and tend to be difficult to service.

In addition, in the apparatus described in GB- A-2,088,195 whereas the first chamber extends over the width of the apparatus and air is impelled into it through a centrally disposed outlet of the fan, the fan

also drawing air from the second chamber, the fan and its housing are arranged outside the chambers and the second chamber extends along one side of the apparatus, which not only tends to make the overall dimensions of the apparatus somewhat large, but also affects the air flow within the apparatus, by reason, it is believed, of the lack of symmetry of the two chambers in relation to the workpiece supporting and advancing means. More particularly the air flow pattern by which air is drawn away from the second chamber after it has been directed against a workpiece will vary according to the position of the workpiece in relation to the inlet of the scroll.

It is thus one of the various objects of the present invention to provide an improved apparatus for use in the treatment of workpieces, more particularly an apparatus of one of the aforementioned types, wherein the various disadvantages recited above are mitigated.

DISCLOSURE OF THE INVENTION The invention thus provides, in one of its several aspects, apparatus for use in the treatment of workpieces wherein jets of air are directed through nozzles on to each workpiece surface to be treated, said apparatus comprising a first chamber which constitutes a plenum chamber, a fan having an impeller by which air is impelled into the first chamber, a second chamber having one or more wall portions in which the nozzles are arranged, whereby air impelled into the first chamber is directed through the nozzles into the second chamber, and workpiece supporting and advancing means for supporting workpieces each with the surface thereof to be treated exposed and for advancing said workpieces through the second chamber along a path past the nozzles, wherein air is drawn from the second chamber , and thus from the vicinity of the workpiece supporting and advancing means, by means of the fan, characterised in that the first and

second chambers are separated from one another by the wall portions, in that the fan is of a scroll-less type, and in that the impeller of the fan is accommodated in the first chamber and the inlet of the fan opens into the second chamber.

It will thus be appreciated that, in the apparatus in accordance with the present invention, the scroll has been dispensed with and the impeller of the fan is now directly accommodated within the first, plenum, chamber, and thus effectively connected directly with the nozzles which form part of the chamber. In this way, the costs of providing a scroll are avoided without any significant loss in effectiveness in terms of the treatment of the workpiece surf ces. In a preferred embodiment of the present invention the inlet of the fan is disposed centrally of the path of the workpieces and the second chamber extends, substantially symmetrically in relation to the fan, along said path. In this way, the efficiency of the fan in terms of drawing air from the vicinity of the workpiece supporting and advancing means is enhanced by reason of the direct, i.e. straight, path extending between the vicinity of said means and the fan inlet.

For further enhancing the air flow within the apparatus in accordance with the present invention, moreover, preferably the first chamber is also disposed centrally of the path of the workpieces and extends, substantially symmetrically in relation to the fan, along said path, the first and second chambers being disposed one above the other. Such an arrangement, it will be appreciated, is advantageous not only in terms of efficiency of the air flow system but also of reducing the overall dimensions of the apparatus, as dictated by the two chambers, thus providing a smaller floor space requirement.

It has also been found that the fan provided in the apparatus in accordance with the invention may be either a backward curved fan or a forward curved fan; both satisfy the required levels of performance. The apparatus described in the aforementioned patent specifications are particularly designed for use in the treatment of shoes and comprise a plurality of channels along each of which shoes are advanced by a conveyor of the workpiece supporting and advancing means. In a preferred embodiment of the present invention channels are similarly provided. Moreover, in such use the fan inlet is disposed centrally of the channels along the length thereof and also over the width of the plurality of channels, and the second chamber extends, substantially symmetrically in relation to the fan, also over the width of the plurality of channels.

In the apparatus described in the two EP specifications referred to above, the first and second chambers are separated by a wall portion which is perforated, said wall portion extending over the width of the apparatus. In the apparatus described in the GB specification, on the other hand, such separation is by a plurality of wall portions defining the channels. The present invention is applicable to both such and indeed similar arrangements.

The apparatus of the present invention also preferably comprises air heating means and steam generating means arranged in the first chamber.

Conveniently the steam generating means comprises a water container and a heating element, the container being removably supported in the apparatus and the heating element being fixedly mounted therein separately from the container. In this way, it will be appreciated, in the event that the container requires servicing or replacement, it is no longer necessary to

dismantle the whole of the steam generating means, but rather the container may be removed while leaving the heating element in position. Moreover, if an extra container (which is relatively inexpensive in comparison with a boiler) is provided, then there need be only sufficient interruption in the operation of the machine to allow the containers to be exchanged, which is a relatively simple operation, and the container which has been removed then being available for cleaning without further interruption of the production cycle. In a preferred embodiment of the invention, furthermore, the steam generating means comprises two water containers each having a heating element associated therewith, said containers being arranged symmetrically in relation to the fan.

It will be appreciated that the water in the or each container requires replenishment from time to time, to which end preferably the or each container is connected to a water source via a pipeline in which e.g. a flow control valve is arranged. It will further be appreciated, however, that the supply of cold water to the or each container is likely to reduce the generation of steam, and consequently in accordance with the present invention, in order to mitigate this effect, the end of the pipeline remote from the water source is located in the (or its associated) container below the water level. In this way the water in the pipeline is pre-heated before entering the container proper.

The above and other of the various objects and several aspects of the invention will become clearer from the following detailed description, to be read with reference to the accompanying drawings, of one apparatus in accordance with the present invention. It will of course be appreciated of course that this apparatus has been selected for description merely by way of

exemplification of the invention and not by way of limitation thereof.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig. 1 is a perspective view of the apparatus in accordance with the invention, this apparatus being a four-channel heat setting apparatus; and

Figs. 2 and 3 are diagrammatic representations indicating the air flow within the apparatus shown in Fig. 1, as viewed in a direction along the length of one of the channels thereof and in a direction across the width thereof respectively.

BEST NODE FOR CARRYING OUT THE INVENTION

The apparatus in accordance with the invention now to be disclosed, which is generally similar, except as hereinafter described to the machine described in GB- A-2,088,195, is a four-channel apparatus for use in heat setting lasted shoes and comprises a framework 10 supported on castors 12 at each corner thereof. At a front portion of the apparatus is a forward extension 14 supporting a plurality of (in this case four) rollers (not shown) around which four conveyor belts 16 pass, each of said belts extending longitudinally of the apparatus and each passing over a second roller (also not shown) supported by a rearward extension 18 of the framework. The second rollers supported in the rearward extension 18 are driven by means of a motor (not shown) accommodated within the extension so that the conveyor belts are movable along a path to carry shoes placed thereon from the forward extension to the rearward extension. Each conveyor belt, which constitutes part of workpiece supporting and advancing means of the apparatus, is of an air-permeable material and is supported, as it moves through the apparatus, on a perforated plate 20 which is in turn supported in the

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framework 10 by a trough-like member 28, a floor portion of which is also perforated. Each belt 16 and its supporting plate 20 constitutes one channel of the apparatus. Between the extensions 14,18, extend the four channels of the apparatus, each of which provides a path along which shoes can be advanced by the conveyors 16. Each channel is defined, and partially enclosed, by two wall portions 24 (Fig 3), but is open at the top. In each wall portion, furthermore, a series of nozzles 26 is provided through which jets of air can be directed onto the surface to be treated of shoes as they are advanced along said path, thus to cause a heat setting operation to be performed on the uppers thereof. (As in the apparatus described in GB-A-2,088,195, the channels are closed at the top by deformable closure members which nevertheless allow the passage of e.g. boot legs protruding therebetween. These deformable closure members are in the form of inflatable bags 28, but in other apparatus in accordance with the invention may be in the form of elongated brush elements or indeed elongated silicone rubber strips which overlap substantially centrally of each channel. )

For supplying air under pressure to the nozzles 26 the apparatus comprises a first chamber 32 in which the impeller of a scroll-less fan 30 is accommodated. The first chamber 32 extends along the whole length of the channels and across the width of the four channels. Moreover the chamber 32 has a plurality of extensions 34 formed by the wall portions 24 so that the chamber is directly connected, and serves to connect the impeller of the fan 30 directly, to the nozzles 26 formed in said wall portions.

In addition, also as part of the air supply arrangement a second chamber 36 is provided which also

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extends along the whole of the length of the channels and across the width of the four channels. The second chamber 36 accommodates the four channels, including the conveyors 16, plates 20 and troughs 28, and the inlet of the fan 30 opens into it, so that the second chamber 36 is directly connected to the channels. In this way the jets of air are directed through the nozzles 26 into the second chamber 36 and the air is then drawn off through the second chamber and fan inlet and is recirculated. As can be seen from Fig. 3, the second chamber

36 is disposed above the first chamber 32 and the two chambers are separated from one another by the wall portions 24.

As can be seen from Figs. 2 and 3, moreover, the fan is located centrally of the paths of workpieces passing through the apparatus both in a lengthwise direction and also widthwise of the four channels. In this way, and by reason of the direct paths between on the one hand the workpiece supporting and advancing means and the inlet of the fan and on the other hand the chamber 32 and the nozzles 36, a simplified efficient air flow is readily achieved.

As already mentioned, the fan 30 is of the scroll-less type. Preferably furthermore it is constituted by a backward curved fan, but, if desired, a forward curved fan may be used in a similar manner with the same degree of effectiveness.

For heating the air circulated within the apparatus, electrical coil heaters, shown diagrammatically at 50, are accommodated within the first chamber 32 and-arranged symmetrically about the fan 30.

The apparatus also comprises steam generating means whereby moisture is introduced into the air circulating within the apparatus. As can be seen in Fig. 2, centrally of the first chamber 32 is mounted a support 40 for two water containers 42, the containers thus being

arranged symmetrically about the fan in a direction lengthwise of the apparatus. Above each water container, furthermore, is mounted an electrical heating element 44 which extends downwardly into, but is not physically connected with, its associated water container 42. Each container 42 has a peripheral lip by which it is readily removably supported by the support 40. Heating the water in the containers 42 causes steam to be generated in the first chamber 32. For supplying water to each container, furthermore, a pipeline 46 is supported by the framework 10 and connected to a supply of water under pressure, through a flow control valve (not shown) of a conventional type. The end of the pipeline 46 remote from the water source is also accommodated within the water container associated therewith so that the water in the pipeline is pre-heated prior to being supplied from the pipeline.

In using the apparatus hereinbefore described, shoes which have been lasted are placed selectively on the conveyor belt 16 of one or other of the channels and are advanced thereby along a path past the nozzles 26 by which jets of air, which has been heated and contains moisture, are directed on to the exposed surfaces of such shoes in order to perform a heat setting operation thereon. When the air has acted on the shoe, it is then drawn downwardly round or through the relevant conveyor belt 16 into the second chamber 36 and then through the inlet of the fan 30, which impels the air directly into the first chamber 32 where it is once more heated by the air heating elements 50 and supplied with moisture by the steam generating means.