In dyeing plants, the coloring powders are weighed, according to preset formulations, through systems that are both automatic and manual ones.

The thereby-weighed powders are then dissolved in suitable tanks equipped with mixer, and sent to the dyeing machines. The common problem both for manual and for automatic powder-weighing machines substantially remains the one of taking the bucket or vessel containing the weighed powders and turning it over into the dissolving vessel, without the coloring powder, that is a highly toxic material that sometimes brings about deadly diseases, coming in contact with working operators being present nearby the machines.

Currently, for those that manually operate, biodegradable bags are available in which powders being weighed are inserted; bag and powders are then thrown together in the dissolving vessel. The bag composed of polyvinyl alcohol dissolves in contact with water making the powder flow that is then mixed. The system is functional enough, but, in addition to its completely manual operation, the bag cost highly affects the working, and the process remains subjected to human errors.

For those that instead operate with automatic powder-weighing machines, the powders are automatically batched in suitable buckets or other vessels made of stainlesss steel that are handled through motored-belt rollers and are addressed to the transferring and mixing stations. For the transfer function, such task is performed by dedicated mechanical hands or robots, that are quite complicated both from the mechanical point of view and from the electric and electronic point of view. These mechanical hands take the bucket, lift it and finally transfer it into the dissolving vessel. Since the dissolving water is always at a certain temperature, when opening the cover, steam fumes are created that in turn get mixed with the powders upon their turning over. In fact, all dissolving devices are equipped with more or less efficient suction hoods. Evidently, this kind of automatisms, robots and dissolving devices is very delicate, since these pieces of equipment are compelled to operate in environments that are saturated with steam, humidity and every kind of exhalations. Plant maintenance is high and the degree of reliability is quite delicate.

Object of the present invention is solving the above prior-art problems, by providing a process and a device that allow doing without all mechanical hands or robots being currently present in this type of plants, introducing as innovative process the emptying and washing of the powder- carrier bucket by using a vacuum suction system.

A further object of the present invention is providing quite static a process and a system; this system staticity confers a very high degree of reliability, the complete removal of obnoxious fumes and a surprisingly simple system.

A further object of the present invention is providing an arrangement through which the powders subjected to a strong damping, given by the dissolving device arrangement, get mixed almost naturally, being the vacuum bubbling so high that clot removal and dye dispersion are almost immediate. Ultimately, one could do without the stirrer, even if for safety reasons the system is anyway equipped therewith. Surely, with respect to traditional systems, the thereby-obtained mixing time is much shorter.

The above and other objects and advantages of the invention, as will appear from the following description, are obtained by a process and a system as claimed, respectively, in Claims 1 and 8.

Preferred embodiments and non-trivial variations of the present invention are claimed in the dependent Claims.

The present invention will be better described by some preferred embodiments thereof, given as a non-limiting example, with reference to the enclosed drawings, in which: -Figure 1 is a schematic top view of the powder-launching station of a preferred embodiment of the system according to the present invention ; -Figure 2 is a schematic side view of the station in Fig. 1; -Figure 3 is a schematic view of a preferred embodiment of the system of the present invention; -Figure 4 is a schematic detailed view of the bucket washing and emptying device in Fig. 3; -Figure 5 is a top view of the device in Fig. 4; -Figure 6 is a detailed view of the device in Fig. 4 applied to a bucket; and -Figure 7 is a schematic detailed view of the dissolving device in Fig. 3.

With reference to the Figures, the system that allows transporting and/or dissolving coloring powders from batching devices to dissolving devices of the present invention, using an adequate process and system, that will be described hereinbelow, initially comprises a coloring powder launching station 1 (Fig. s 1 and 2) from a bucket 3 to a dissolving device. In the embodiment shown, for a comfortable and quick operation, two launching locations 7 and 9 are provided, but obviously any number thereof could be adopted at will. The buckets (or similar containers made of suitable material) 3 made of stainless steel coming from the weighing system 11 equipped with rollers 13 are addressed to the launching station 1. In such station 1, there will be, in the embodiment shown, a bucket 3 being transferred and a bucket 3' waiting. The system software controls will establish the launching point according to the applications. Through pushing means 15, for example pneumatic ones, the bucket 3 will be displaced from the rollers 13 of the powder-weighing system 11 from position A to position A1, or from position B to position B1 in Fig. 1, should position A1 be already busy.

In position A1 or B1 in Fig. 1 or 2, the buckets 3 are placed under a plate 17 (Fig. s 2-6) on which emptying devices and all function valves are assembled. Once having been placed under the plate 17, the buckets are lifted by lifting means 18 till they are connected with the corresponding plate 17: thereby, there will be the working arrangement shown in detail in Figure 6. Obviously, the arrangement being shown is only a non-limiting example of the invention, since similar devices could be provided to perform the claimed process.

With general reference to Fig. 3 and with particular reference to Fig. s 4 to 6, the plate 17 is equipped with a valve 19 for letting in water or another washing liquid; such valve is connected to a washing ball 20 placed on the opposite side to the plate 17: the ball 20 is equipped with a plurality of small holes to let the washing liquid out. Moreover, the following are provided: a valve 21 without flange, drilled in its upper part to let vacuum in; couplings 23,25,27 for air-inlet valves 29,31,33, that take to respective ducts 35,37,39 connected to a drainage 41; a solenoid valve 43 to let air in in order to empty the ball 20; a pneumatic cylinder 45 showing the level of powders (sleeve) in the bucket 3; a stub pipe 47 of the female type for a probe 48 for the minimum washing water level; and a stub pipe 49 for a probe 50 for the maximum washing water level.

As better appears in Fig. 3, the system of the invention preferably comprises two plates 17 (identical and therefore shown by the same reference numbers) to be connected to respective buckets 3, even if the number of plates 17 is not limiting. Such plates 17 are connected to respective dissolving drums 51 (that are mutually identical, apart from the absence of water valves in one of them), shown in detail in Fig. 7.

Such dissolving drums 51 are known in the art and the present invention allows applying them to the system of the invention without any meaningful change, thereby allowing the system of the invention to be easily adapted to already existing solutions in the art. The dissolving drums 51 are equipped with: a ball valve 53 and a ball valve 55 to empty them, a ball valve 57 and a three-way valve 59 to let in compressed washing air and water, respectively.

The system in Fig. 3 further comprises a pump 61 to sent the dye to users 63; a three-way valve 65 for the discharge; a valve 69 to wash the drum 51; valves 71,73 and a flange 75 for the vacuum pipe 76; an automatic valve 77 for the vent pipe 78; an automatic valve 79 for vacuum pipes 80; and a porthole 81 with flange.

A possible stirrer 83 to be applied to the porthole 81 flange, a sleeve 85 for the pneumatic vacuum probe (not shown), a sleeve 87 for a temperature probe (not shown), a sleeve 89 for a full-state probe (not shown) and a vortex-breaking plate 91 are further provided.

The system in Fig. 3 comprises, as regards the compressed air system, a tank 93 (whose capacity is for example 270 liters), a filter-reducer-manometer assembly 95, a float condensate discharger 97 and a flow-rate shutting cock 99: the tank 93 is connected through pipings 94,96,98 to the buckets 3, and through pipings 94,96,100 to the drums 51.

The system in Fig. 3 finally comprises, as regards the vacuum system, a tank 101 (whose capacity is for example 270 liters), an automatic valve 103, a float level 105 to empty the condensate, a check valve 107, a filter 109, a vacuum pump 111, a return valve 113, a tank 115 (whose capacity is for example 200 liters), an automatic valve 117 to let water in, a temperature probe 119 and a maximum level detector 121.

The operation of the system according to the present invention will now be described.

After having been connected to the plate 17, a bucket 3 is subjected first of all to the powder transfer. Through the liquid-ring pump 111 or the like, vacuum is realized into the tank 101. The pump 111 suction line will be equipped with the filter 109 and the check valve 107. The tank 115 or a similar, suitable vessel for water or another liquid supplies the cooling and cushioning water to the pump 111. The tank 101 is connected through a piping 102 to the different dissolving drums 51 with automatic valves 71. The dissolving drums 51 in turn are connected to the launching station 1 through the automatic valves 21. The decision about which launching station has to be adopted is taken by the valves 125 and 127. The vacuum transport of powders to drums 51 is performed through respective pipes 124,126,128.

The circuit allows the launching station 1 to send the powder into one of the dissolving drums 51. Before every powder launch into the involved drum 51, an hydraulic guard is created by letting water in from valves 69 and the related flow-rate counter. Once having created the hydraulic guard, the vacuum operation is started by valves 71 and through valves 125 and 127 into the powder-carrier buckets 3 through valves 21. The involved bucket 3 will start to transfer powder under vacuum. The transfer operation is very quick (of the order of 150. 300 1/second). When sucking the powder, the cylinder 45 indicating the level of powder presence will also be activated. As soon as vacuum is activated when sucking, air at atmospheric pressure is inserted into the bucket through the valve 23.

Upon reaching the lack-of-powder level signalled by cylinder 45, valve 23 or 25 is alternately opened, to rotate the powder remaining on the bucket 3 bottom. This alternate movement makes all remaining powder transferred into the dissolving drum 51. The time for this operation is about 30", while the bucket 3 is emptied in about 2'.

The powder violently immersed into the dissolving drum 51 is immediately mixed with the hydraulic guard water thereby obtaining an unexpectedly optimum mixing effect, so that the mechanical effect of a blade stirrer 83 can be deemed quite superfluous.

After every transfer, washing operations occur. Always under vacuum action, water or another liquid is inserted into the bucket 3 through the valve 19 and the related flow-rate counter 150 connected to water supply lines (not shown) and to the valve 19 through the piping 98. Through the washing ball 20 the walls are washed and the vacuum sucks water from the bucket 3 to the drum 51. These washing operations are normally two, but their number is not limiting for the present invention.

Washing waters are provided in a circuit.

During washing, receipt-making water is also inserted into the dissolving drum 51, through the automatic valve 69. In case of hot water, the insertion of such waters occurs after having washed the bucket 3, since the vent valves 77 of the drums 51 must be opened.

At the end of washings of the bucket 3, it is possible to perform a further washing by discharging the water in a sewer through the valve 129 and the pipe 130.

The bucket 3, once being washed, is dried through vacuum; by exploiting the hydraulic guard bubbling, colour mixing is obtained and the bucket 3 is automatically dried. The bucket 3, once being dried, is automatically taken back to the rollers 13 of the powder-weighing system 11 and goes back into the cycle.

The thereby-mixed colour is sent to users 63, through the valves 53 and 55 and the pump 61. When such trasfer is performed, the dissolving drum 51 is washed and the lines are blown.

As regards all other parts and connections described, the system of the present invention behaves like any system known in the art, and its related operation description will be omitted.