SUCTION UNIT FOR INDUSTRIAL WORKING LIKE IN PARTICULAR, BUT NOT

EXCLUSIVELY, THERMAL CUTTING

DESCRIPTION

Field of the invention

The present invention refers in general to the field of suction systems for industrial working like, for example but not exclusively, thermal cutting.

Background of the invention

Thermal cutting processing is currently carried out with the assistance of suction units suitable for keeping the work area as free as possible from the polluting fumes that the processing itself generates. To this purpose, suction and filtering units of significant bulk are used, in which a suction surface of substantial size is provided with a distribution of a plurality of filtering elements such as cartridges or filter bags, capable of ensuring effective operation for at least one work day, at the end of which a cleaning of the filtering elements is carried out so that the effectiveness of the unit is restored and the work can go on.

Nevertheless, the loss of suction/filtering efficiency is a situation that frequently occurs whether due to an incorrectly sized filtering surface, or because the apparatus is subjected to excessively critical work conditions with respect to those for which it is designed. The filtering cartridges can clog up to the point of sometimes imploding, making it necessary to replace them, with consequent idle time, in order for the work to be able to start again.

In order to avoid such a drop in efficiency of suction and the saturation of the cartridges, automatic cleaning systems are known that take advantage of a counter- current pneumatic flow. In such systems, each filtering cartridge is equipped with a suitable valve, the actuation of which takes place individually, in groups or in cascade. In these cases cleaning is normally carried out in two stages, one during the operation of the suction and one at the moment when the machine is shut down.

In the first step, while the group sucks, the counter-current cleaning must at the same time overcome the normal suction flow; in fact, the two flows tend to cancel each other out, making both the suction and the cleaning not very efficient. In order to at least partially compensate for such inefficiency, as mentioned, the valves are actuated individually, in groups or according to a cascade cycle so that at each moment there are no more than two cartridges simultaneously involved in cleaning.

In the second step, with suction switched off and lasting even a few hours (at the end of a day at full workload), a really complete and correct cleaning of the cartridges is carried out.

Conventional systems tend to mount cartridges of a length of about 660 mm, since conventional counter-current automatic cleaning fails to complete cleaning of any efficiency on cartridges which are longer than that. Moreover, the valves are normally installed in a fixed manner at a certain distance from the aperture of the cartridge (about 250mm), to still allow the suction air flow to pass, which ensures that the compressed air reaches to some extent the inside of the cartridge, but a large amount is dispersed in the cartridge housing.

Other systems, in order to avoid said problem, provide for fixed nozzles that each penetrate the inside of its cartridge, without however significant improvements in efficiency and in any case introducing constructive complications.

Summary of the invention

With the present invention a suction unit is now provided that is generically of the type introduced above, but which thanks to a new configuration allows for greater efficiency of cleaning, in particular without interrupting normal operation and without significantly impacting on the efficiency of suction in progress.

Such a result is achieved by the suction unit for industrial working like in particular, but not exclusively, thermal cutting according to the present invention, the essential characteristics of which are given in attached claim 1. Further important characteristics are then given in the dependent claims.

Brief description of the drawings

The characteristics and advantages of the suction unit according to the present invention will become clearer from the following description of an embodiment thereof, provided as a non-limiting example with reference to the attached drawings, in which:

- figure 1 shows an axonometric view of the unit according to an embodiment of the invention, some parts of the cover frame being omitted and in particular without a side panel so as to show the internal configuration of a housing space for the filtering cartridges and of a heavy dust collection area;

figure 2 is an axonometric view of the unit, with in the foreground a side that remains in the back in the view of figure 1 , also in this case with parts removed to show the internal configuration of a cleaning chamber opposite the housing of the cartridges and accommodating a cleaning system for the same cartridges, as well as a further housing for the suction-producing means such as a fan;

figure 3 again shows an axonometric view of the unit from the front, again with parts removed to show the inside of the unit, in particular a distribution gap for distributing the suction flow towards the cartridges; and

figure 4 is a side view of the unit, from the side in the foreground in the previous figure 2 and again with the respective cover frame panel removed in order to allow for the internal parts to be seen.

Detailed description of the invention

With reference to the above figures, the suction unit according to the invention comprises a box-shaped cover frame 1 , typically parallelepiped rising up from a base plate 1 1 intended to rest on the ground and provided with seats 1 1 a for the engagement of standard forks of fork-lifting means, to facilitate the transportation of the unit.

The structure of the cover frame 1 therefore comprises, as mentioned in elevation from the plate 1 1 , on a front side, a front panel 12 provided at a lower part with an opening 12a formed for the entry of the fumes resulting from the specific working or processing in the area. The front side is indeed the one intended to face the processing/working area and/or to be connected to a suction duct, such as a duct able to be directly connected to a machine tool, for example to the base housing of a thermal cutting machine. The opening 12a can for this purpose be provided with quick release locking means for connection to the duct, or can even integrally be provided with the aforementioned duct or a part thereof. The front panel 12 also provides for, at roughly a half of its side-to-side development, a rib 12b which will be discussed further on. At a position opposite the front side, the cover frame 1 comprises a rear side in the form of a rear panel 13. The extension of the cover frame is completed by two flanks 14, 15, which join together the front side and the rear side, and by a covering panel or roof 16.

The internal volume of the frame is partitioned by various partition walls and diaphragms that divide it into different housings and chambers as described hereafter. A central diaphragm 17 rises from the plate 1 parallel to the flanks 14, 15, so as to run between the front side, from the inner rib 12b of the panel 12, and the rear panel 13. The two inner regions thus divided by the central diaphragm 17 comprise an air inlet region 2 of air polluted with the processing fumes, between the diaphragm and a first flank 14, and an air outlet area 3 of the filtered air delimited between the diaphragm and a second flank 15.

The inlet region 2 is the one closed at the front by the surface of the front panel 12 and is in turn internally partitioned by a distribution wall 18 that rises up parallel to the front panel itself near to it. A distribution gap 21 is thus defined in cooperation with the front panel 12 immediately downstream of the inlet opening 12a. The remaining part of the inlet region, i.e. the one comprised between the distribution wall 18 and the rear panel 13 comprises a top housing 22 for housing filtering cartridges 5 as discussed hereafter.

The housing 22 communicates with the gap 21 , to receive the inlet pneumatic flow from it, through slits 18a on the wall 18. Below the housing 22 the inlet region is occupied by a heavy dust collection drawer 6, equipped with a hopper 61 and that can be pulled out thanks to the support of wheels or other sliding support systems. Suitable doors, not represented, allow for independent access to the two parts (region 22, region of the collection drawer) from the relative flank 14. The doors are of course equipped with gaskets, which in the closure position ensure the pneumatic seal, insulating the cover frame from the outside.

The outlet region 3 communicates with the inlet region 2 through holes 17a formed in the central diaphragm and blocked by the aforementioned cartridges 5 which, having a cylindrical structure, project in the inlet region 2. The holes and correspondingly the cartridges are typically organised, like in the example, according to a rectangular matrix. The part of the diaphragm on which the holes 17a open laterally delimits, in cooperation with the second flank 15 and with a plate 19 parallel to the base plate 1 1 , a cleaning chamber 31 which receives the filtered air indeed coming from the aforementioned holes 17a.

The plate 19 has a first passage 19a that opens the cleaning chamber on an underlying housing 32, accommodating a suction propulsion device, such as a conventional fan 4. A second passage 19b is formed in the plate 19 and in correspondence to it a filtered air outlet chimney 9 rises towards the roof 16, opening at it through a passageway 16a. The entire path followed by the flow of air with relative pollutants is symbolised by arrows A (polluted air), B (filtered air) and C (heavy dust).

Going back to the cleaning chamber 31 , a counter-current cartridge cleaning device 8 is mounted on the relative face of the central diaphragm 17. The device comprises a shutter 81 suitable for selectively blocking just one of the various holes 17a. A system of slides 82, 83 in a Cartesian arrangement, and relative linear actuators 84, 85, according to what, if considered as such, can be obviously implemented, is adapted to take care of such a motion of the shutter, commanded and controlled again in an obvious manner, with the help of standard position sensors, by control system for managing the unit. Other different actuation systems can be adopted in an equivalent manner.

On board the shutter 81 a known pneumatic solenoid valve 86 is installed, with suitable pneumatic connection and feed, for injecting in the hole, and therefore towards the cartridge, again upon programmed instructions of the control system, a cleaning jet in counter-current with respect to the suction jet. The movement of the shutter (see for example the different position between figures 2 and 4) clearly has the effect of selectively managing the cleaning in counter-current of just one of the filters at a time, leaving the others completely free. A door 12c formed on the front panel 12, also pneumatically sealed in the closure position, allows for an access to the cleaning chamber 31 for control and maintenance needs.

The unit according to the invention, thanks to the configuration just described, offers some crucial features permitting to avoid the basic problems that generate situations of: • low suction efficiency;

• low filtration efficiency;

• thermal cutting machine shut down, need for long post-cleaning;

• need to change cartridges and other maintenance costs;

• need to use "short" cartridges or supplementary accessories/mechanisms for cleaning if longer cartridges are used.

Thanks to the particular cleaning system, with the single shutter that closes the filters individually and in succession according to programmed sequences, and with the dual function of blocking the suction flow in the cartridge and permitting the passage of only the cleaning flow using compressed air, the effectiveness of the suction is not significantly compromised, because all of the filters not occupied by the shutter normally work without any load loss.

As well as this, the organisation of the inlet area 2 with the distribution gap 21 which distributes the flow in the housing of the cartridges 22 through the slits 18a of the distributing panel 18 (slits corresponding with the rows of cartridges installed horizontally), the air is conveyed under the effect of the depression created by the fan so as to evenly and homogeneously distribute the air loaded with fumes and dust among the various cartridges.

To summarize, there is the possibility of managing the work without stops, even doing without the need for a post-work final stage. Maintenance is simple, there are lower management costs and lower energy consumption, and the possibility of using cartridges of greater length with respect to known units thanks to the efficiency of the internal configuration of the cleaning system. The unit is also extremely compact, sized for use also for manual thermal cutting processing.

The present invention has been described with reference to preferred embodiments thereof. It should be understood that there can be other embodiments within the scope of protection defined by the claims here attached.