Machine for cleaning and drying small items

Abstract: The machine for cleaning and/or drying metal and non-metal items comprises a drum with a sealable charge/discharge port, and a single cage in which to place the items (typically nuts and bolts); the cage is rotatable about a horizontal axis in either direction and embodied frusto-conically at least in part, its narrower end open to provide a charge/­ discharge port coinciding with that of the drum. The conical part of the cage, at least, is provided internally with one or more helical ribs departing from the relative port and extending the full axial length of the cone, the purpose of which being to propel the charge steadily and uniformly away from and toward the port. The solvent used for cleaning purposes is sprayed straight into the cage so as to invest the nuts and bolts directly.

Description: The present invention relates to a machine for cleaning and/or drying metal and non-metal objects, particularly small items and mechanical components; the machine is of a type designed essentially to wash such items in solvent internally of a sealed chamber or drum, from which the solvent can be recovered and recycled, and to dry them in the selfsame drum by means of hot air forced into the relative enclosure from a closed circuit. In machines of the type in question, the drum is provided internally with a revolving element, or rotor, carrying containers in which the items for cleaning are placed; the containers are embodied with perforated walls, and can be associated with the rotor in one of two conventional arrangements -viz, as buckets, hung from pivots, or as cages rotatable about respective axes lying parallel to the axis of rotation of the rotor. Machines incorporating the rotary cages are thus capable of greater levels of efficiency, that is to say, items can be cleaned more thoroughly and more quickly, even those exhibiting holes, recesses or flat profiles, or of geometry otherwise difficult to cleanse by simple immersion, however suitable the solvent. In such machines, in fact, the items being cleaned are made to rotate continuously in relation to the axis of rotation of the cage in which they are carried, and will therefore change position continually while immersed in the solvent as long as the rotor and the cage are kept turning. Nonetheless, these all-rotary machines also betray a certain lack of efficiency, insofar as the degree of contact between the solvent and the immersed items remains insufficient. The drum may simply be filled to a given level with the solvent, or alternatively, the solvent can be sprayed in; in the first instance, the cage and its contents submerge gradually in the solvent, and in the second, are invested by the spray. The further alternative exists of ducting and spraying in the solvent simultaneously. Whichever method is actually adopted, the cages are immersed in or invested by the solvent before their contents, so that contact between the solvent and the items to be cleaned is effectively retarded. The cage walls, in fact, present an obstacle to the solvent flowing toward the items, notwithstanding their perforations. The most immediately apparent of remedies could be to embody the walls of the cages in mesh, thereby providing holes of significantly larger dimensions, though this expedient creates problems as regards the containment of small items, such as nuts and bolts etc., which would be able to pass through the holes. Another problem is that contact between the solvent and the items to be cleaned is less than wholly continuous, given that the revolving motion of the rotor causes the cages to pass in and out of the solvent, repeatedly submerging and emerging. Yet another difficulty connected with the machines in question derives from the fact that the cages containing the items to be cleaned are immersed continually in a solvent that becomes increasingly soiled with the dirt shed from previous charges. Italian patent n° 1 049 134 discloses a machine for cleaning small metal items, such as nuts and bolts, that makes use of a single rotatable cylindrical mesh cage, mounted coaxially within the drum and supporting and accommodating a second cylindrical mesh cage, or ante-cage. The items to be cleaned are placed in the ante-cage, whereupon this is inserted in and attached to the cage such that the two rotate as one about a common axis. The drum having been sealed and filled with solvent to a prescribed level, the cage is set in rotation about its own axis, causing the ante-cage to rotate likewise; thus, the items are cleaned by immersion in the solvent in this case also. In another embodiment of the same machine, the cage and ante-cage are integral, and associated with a coaxial funnel-like structure that converges on and engages the interior of the ante cage by way of its smaller diameter end. Inside the ante-cage, the narrow end of the funnel operates in conjunction with a helical structure attached permanently to the cylindrical wall of the ante-cage and serving to direct the contents toward and away from the funnel. Not only do the drawbacks of cleaning in solvent by immersion remain in a machine embodied thus; there are also difficulties with loading and unloading. In operation, the items are charged into the ante-cage by falling free from the mouth of the funnel, and when discharging, regain the funnel by falling free from the helical structure only on its arrival at a height above the horizontal diameter of the ante-cage. The items are thus thrown against one another and against the surfaces of the structure with a relatively violent impact, and can become irreversible defaced; this is true of small items such as bolts, for example, which are provided with an external thread and can therefore damage easily. Moreover, the machine can discharge only at given intervals, on arrival of the helical structure at a position in which it lies at a height above that of the axis of the ante-cage and is angled toward the mouth of the funnel-like structure; only in this configuration, in effect, are the items carried by the helical structure able to fall in the direction of the funnel. To overcome these problems the United States Patent US-A-4719933 (Jackson) proposes a machine for washing workpieces in which the workpieces are delivered into the entrance end of a rotating horizontal drum and are advanced axially through the drum by an annular conveyor flight extending around and along the inner wall of the drum. During the advance the workpieces are sprayed directly with a cleaning solution, then the workpieces are dried by heating coils prior to being discharged from the drum. Also with this machine a relative violent impact of the workpieces against one another and against the surfaces of the structure is not avoided. Besides the charge/discharge of the machine can be effected only with the machine stopped. Accordingly, the object of the present invention is to provide a machine of the type described above in which even small items, such as nuts and bolts, are brought more directly into contact with the solvent, and which loads and unloads swiftly and continuously. The stated object is realized in a cleaning and/or drying machine for small metallic and non-metallic items as characterized in the appended claim 1, which comprises a drum with a sealable charging and discharging port, and a single cage for receipt of the items to be cleaned that is rotatable in either direction about a horizontal axis. The cage is frusto-conical, at least in part, its smaller base remaining open to function as a charge and discharge port, and provided internally with at least one rib, departing from the charge/discharge port and extending helically for the entire axial length at least of the frusto-conical section, the purpose of which is to ensure a continuous, uniform propulsion of the items for cleaning at unvarying volume, away from and toward the port, The machine further comprises means for supplying solvent, associated with the drum, which operate internally of the cage and spray the items direct. A great advantage provided by the present invention over the various arrangements described above, is gained through the certainty that all surfaces to be cleaned are brought fully into contact with the cleansing medium, given that the items are tumbled continuously in the single cage of the machine and invested totally by solvent sprayed directly into the relative enclosure. A further advantage of the machine according to the invention is the facility it provides of investing the tumbled items continuously with clean solvent, as the soiled fluid drains away continuously and is redirected into the cage only after passing through an appropriate filter. The invention will now be described in detail, by way of example, with the aid of the accompanying drawings, in which: figs 1, 2 and 3 illustrate the machine according to the invention, schematically, in three different configurations that occur during operation, namely: charging, cleaning and/or drying, and discharging; fig 4 illustrates an alternative embodiment of the machine of figs 1, 2 and 3, seen in the cleaning and/or drying configuration. With reference to the drawings, a cleaning and/or drying machine according to the invention consists substantially in a drum 2, and a single cage 7, accommodated by the drum 2, in which items 4 are placed for cleaning. The drum 2 is essentially cylindrical, and provided with a coaxially disposed port 3 at one end through which items 4 are charged and discharged, means 5 by which to direct solvent and/or a hot drying fluid into the drum 2, and an outlet 6 at bottom through which the fluids discharge. The cage 7 is embodied in two successive sections, the one frusto-conical and the other cylindrical, which are disposed coaxially with one another, and with the drum 2. The diameter of the cylindrical section, denoted 13, is equal to the diameter of the greater base of the frusto conical section, denoted 8, and joined permanently and coaxially thereto by one of its circular bases. The remaining base of the cylindrical section 13 is blanked off by a circular end wall, or baffle 17, rigidly and coaxially associated with a supporting shaft 18 that projects externally from the drum 2. The remaining, smaller diameter base of the frusto-conical section 8, hence of the cage 7, exhibits a rigidly attached external hoop 28 cradled in a plurality of freely-revolving rollers 29 that are associated with the drum 2 and carry the cage in conjunction with the shaft 18. The narrow base of the frusto-conical section 8 is open, in such a way as to create a port 9 through which items 4 are charged and discharged into and from the cage; more exactly, the port 9 of the cage coincides coaxially with and projects marginally from the port 3 of the drum 2. The cage 7 is able to rotate within the drum 2 in either direction about its own axis, set in motion by drive means (not illustrated) connected to the shaft 18. 10 denotes at least one helical rib associated with the internal wall of the cage 7; more exactly, in the interests of simplicity, the phantom line 10 of the drawings shows the path described by just one such rib along the frusto-conical section 8, which is angled from the generators of the cage in such a way as to carry the charge of items 4 away from or toward the port 9, depending upon the direction of rotation (denoted fc or fs in figs 1, 2 and 3). According to the invention, the internal ribs 10 of the frusto-conical section 8 serve exclusively to propel the items 4 along the axis of the cage 7; the cylindrical section 13, on the other hand, is provided with ribs 14 that are designed to produce a tumbling action. Each of the first ribs 10 will encircle the axis of the cage 7 more than once, describing a helix of which the pitch decreases progressively the greater the distance from the charge/discharge port 9, the effect being to moderate the speed with which the items 4 are propelled from the port 9 toward the end baffle 17. 27 denotes a frusto-conical rim rigidly associated with the exterior of the frusto-conical section 8 of the cage at the narrow base. The revolving walls of the cage 7, denoted 7a, are perforated in such a way that the solvent can drain through, whereas the baffle 17 is embodied solid to advantage, for reasons that will become apparent in due course. The outlet 6 of the drum 2 is located substantially to coincide with the cylindrical section 13 of the cage 7 and controlled by a shut-off valve 19; also installed on the outlet line is a filter 20, by which foreign matter entrained in the discharging solvent is trapped. 16 denotes the cover of the drum 2, which fits over the port 3 and is capable of movement between a charge/discharge position, in which the port 3 is left entirely free (figs 1 and 3), and an operative cleaning and/or drying position in which the port 3 is sealed over (fig 2). Means 5 for supplying the enclosure with solvent, and if envisaged, with a drying fluid, consist in a pipeline 12 of which one end is open, and carries a nozzle denoted 11 (fig 2) directed into the cage 7 and at its contents. In the embodiment of figs 1...3, the pipeline 12 is embodied in two parts 12a and 12b, one associated permanently with the drum 2 and the other with the cover 16. The first part or pipe 12a passes through the wall of the drum 2 at a point adjacent to the port 3, its open end directed parallel with the axis of the drum 2 and facing toward the cover 16. The remaining pipe 12b is U-shaped, in such a way as to enable its being positioned with one end offered to the open end of the first pipe 12a and coupled thereto coaxially in a fluid-tight fit, and the other end disposed coaxially with the axis of the cage 7, when the cover 16 is closed. It is with the last-mentioned end of the U-shaped pipe 12b that the nozzle 11 is associated in such a way as to project the solvent 21 into the lower half of the cage 7, as illustrated in fig 2. Likewise as illustrated in fig 2, the first pipe 12a runs from the outlet of a three-way valve 22, of which the relative inlets are connected to a pipeline 23 carrying solvent, and to a pipeline 24 carrying a drying fluid. 15 denotes means, associated with the drum 2, by which to charge the cage 7 with the items 4 for cleaning; in the embodiment illustrated, such means consist in at least one recipient 25, of which one side wall 26 is canted at a significantly obtuse angle in relation to the base. The recipient 25 is disposed with its angled wall 26 adjacent to the port 9 of the cage 7, supported by conventional means (not shown) by which it can be moved between at least three limit positions, namely, charge, discharge and at-rest. In the charging position, the recipient 25 is supported at a height equal to or greater than the lowest point of the port 9 of the cage 7, and positioned with its angled wall 26 adjacent thereto, in such a way as to create a substantially unbroken surface with the wall 7a of the cage (see fig 1). With the machine discharging, on the other hand, the recipient 25 is positioned lower down, its angled wall 26 adjacent to, aligned and creating a substantially unbroken surface with the frusto-conical rim 27 (see fig 3). When in the at-rest position, the recipient 25 is distanced from the port 3 of the drum 2 altogether, so as to permit of shutting the cover 16. Also associated with the recipient 25 will be means (not illustrated) that permit of regulating the flow of items 4 charged into the cage 7, so as to ensure that the transfer occurs at speed and volume substantially the same as are generated internally of and through the frusto-conical section 8 of the cage. Referring to figs 1...3, and assuming the machine to be in a situation such as would obtain at the beginning of a working shift, the cage 7 and the recipient 25 will both be empty and the cover 16 distanced from the charging port 3. Having filled the recipient 25 in the conventional manner, the cage 7 is set in rotation in the direction fc as indicated in fig 1, i.e. such that the spiralling motion of the ribs 10 draws the charge from the port 9 toward the end baffle 17. The recipient 25 is then manoeuvred into the position of fig 1, whereby the angled wall 26 is set substantially in alignment with the bottom-most generators of the frusto-conical section 8 of the cage, its free edge all but in contact with the ends of the rotating helical ribs 10 nearest the port 9. In this situation, the items 4 gradually run off the angled wall 26 of the recipient 25 onto the revolving frusto-conical wall 7a, without falling appreciably, where they are taken up by the helical ribs 10 and propelled at uniform speed and volume toward the cylindrical section 13. Once emptied, the recipient 25 is distanced from the port 9 of the cage 7, whereupon the cover 16 is placed over the port 3 of the drum 2 and made fast, creating a fluid-tight fit (fig 2). As a result of fitting the cover, the two pipes 12a and 12b of the solvent supply line 12 are brought into contact and the nozzle 11 directed into the cage 7, and more exactly, into the bottom half of the cage. Operating the valve 22 at this point, a pressurized spray of solvent 21 is produced from the nozzle 11 and directed without hindrance at the items 4 in the cage 7, which continues rotating in the direction denoted fc ; accordingly, the charge continues to be turned over by the action of the ribs 10 and 14, but tumbled, to advantage, rather than thrown. The shut-off valve 19 will be open thoughout this stage, so that the soiled solvent 21 can drain away continuously and pass through the filter 20, thus removing foreign matter shed from the items 4. With the cleaning cycle completed, the valve 22 can be switched to supply a drying fluid to the nozzle 11, if a drying step is envisaged. With the cleaning and/or drying steps accomplished at all events, the shut-off valve 19 is closed, the cover 16 removed, and the recipient 25 then offered to the port 9 of the cage, its angled wall 26 this time substantially in alignment with the bottom cone generators of the rim 27, and the edge all but in contact. The direction of rotation of the cage 7 is now reversed (see arrow fs , fig 3) in order to propel the items 4 from the end baffle 17 back toward the port 9; again, the charge moves through the cage steadily, that is, at uniform speed and volume, and tumbling rather than being thrown. A machine thus embodied can provide high levels of efficiency, as the charge is invested directly by the solvent, and tumbled steadily in such a way that the single items 4 continually offer different surfaces to the projected spray. When charging and discharging, moreover, the items are subjected to a propulsion force devoid of sharp acceleration and deceleration components, so that mechanical shock and defacement are avoided. Fig 4 illustrates an alternative embodiment of the machine, in which the cage 7 is entirely frusto-conical; operation of the machine remains the same. In this embodiment, moreover, the interior of the cage 7 exhibits a plurality of helical ribs 10 of which the height, measured from the inside wall of the cage with which they are associated, decreases progressively as the longitudinal distance from the port 9 toward the baffle 17 increases, in such a way that the surface area of the ribs 10 offered to the items 4 remains uniform along the axial length of the cage; accordingly, the charge is propelled through the cage at unvarying speed and volume in either direction. It will be observed that the shaft 18 of the cage illustrated in fig 4 is hollow, and accommodates a single pipeline 120 the projecting end of which carries a nozzle 11 directed down toward the bottom half of the cage 7 where the charge accumulates. With this arrangement, in which the nozzle 11 and the port 9 occupy opposite ends of the machine and the lower half of the frusto-conical section 8 thus faces the nozzle, the supply of solvent can also be activated to coincide with the charging operation, so as to invest the oncoming items 4 during their steady and uniform progress toward the nozzle 11.

Claims: A machine for cleaning and/or drying metal and non-metal objects, typically small items and mechanical components, in particular nuts and bolts, comprising a single cage (7) for receipt of the items (4) to be cleaned, a helical conveyor rib (10) means (5) for supplying solvent (21) and solvent spraying means (11) operating internally of the cage (7) and bringing the items (4) directly into contact with the solvent; an outlet (6) through which to drain at least the solvent (21); characterized in that it comprises: a sealable drum (2) having a port (3) through which items (4) to be cleaned can be charged into and also discharged out of the relative enclosure, provided with means (5) for supplying solvent (21) and/or drying fluid to the enclosure the cage (7) being rotatable internally of the drum (2) in either direction about a horizontal axis, embodied with a substantially frusto-conical section (8) extending over almost its entire axial length of which the smaller base remains open to provide a charge/discharge port (9) that coincides with the charge/discharge port (3) of the drum, and of which at least the revolving walls (7a) are perforated and provided internally and for the entire axial length of the frusto-conical section (8) with at least one helical rib (10) ensuring continuous and uniform propulsion of the items (4) for cleaning at a substantially constant flow of items away from or toward the charge/discharge port (9) of the cage (7), depending upon the direction of rotation, means (15) for charging and discharging items (4) into and from the drum (2), located externally of the drum and separate from the cage (7), providing a surface (26) for the support and transfer of items (4) that can be positioned adjacent to the charge/discharge port (9) of the cage (7) during both charging and discharging operations, in such a way as to create a substantially unbroken surface in conjunction with the revolving walls (7a) of the cage. A machine as in claim 1 comprising solvent spraying means that consist in at least one nozzle (11), associated with the end of a pipeline (12) of which at least the end fitted with the nozzle (11) is capable of movement between a charge/discharge position, in which the pipeline (12) is distanced from the port (9) of the cage (7), and a cleaning and/or drying position in which the pipeline (12) and nozzle (11) are directed into and toward the bottom half of the cage (7) where the items (4) for cleaning accumulate, and the remaining end connects with a supply of pressurized solvent whenever the nozzle (11) is directed into the cage (7). A machine as in claim 1 comprising solvent spraying means that consist in at least one nozzle (11) associated with the free end of a pipeline (120) inserted through a hollow shaft (18) by which the cage (7) is carried and driven, and directed toward the bottom half of the cage in which the items (4) for cleaning accumulate, of which the remaining end is connected externally of the cage (7) to a supply of pressurized solvent. A machine as in claim 1, wherein the cage (7) is extended beyond the greater base of the frusto-conical section (8) into a cylindrical section (13) of diameter equal to that of the greater base, provided internally with at least one rib (14) angled in relation to the cylindrical generators, by which items (4) occupying the cage are tumbled. A machine as in claim 2, comprising a cover (16) associated with the charge/discharge port (3) of the drum (2) and capable of movement between an open position, in which the charge/discharge port (3) is exposed to enable the passage of items (4) for cleaning into the cage (7) or of cleaned items (4) from the cage, and a closed and sealed position assumed during the steps of cleaning and/or drying the items (4), when solvent and/or vapour are able to leave the drum (2) solely by way of a relative outlet (6), wherein the pipeline (12) is embodied in two parts of which a first (12a), permanently associated with the drum (2), connects by way of one end with the supply of pressurized solvent and terminates with the remaining end adjacent to the charge/discharge port (3) of the drum (2), facing outwards, and a second (12b), fitted with the nozzle (11), is permanently associated with the cover (16) and designed to enter into direct contact with the first (12a) when the cover (16) assumes the closed position. A machine as in claim 1, wherein charging and discharging means (15) consist in a recipient (25) of which one side wall (26) is angled obtusely in relation to the base, and are capable of movement at least between a charging position, in which the recipient (25) is disposed with the free edge of the angled wall (26) substantially tangential to the smaller base of the frusto-conical section (8) of the cage (7) and the angled wall substantially in alignment with the bottom cone generators of the cage in such a way that items (4) can run from the recipient (25) into the cage (7) without falling in space, a discharging position, in which the angled wall (26) of the recipient lies substantially in alignment with the bottom generators of a frusto-conical rim (27) issuing divergently from the charge/discharge port (9) of the cage (7), and an at-rest position in which the recipient (25) is distanced from the cage to permit of implementing the operation whereby items (4) are cleaned and/or dried, and wherein at least the volume of items (4) charged from the recipient (25) into the cage (7) is monitored and controlled by means associated with the charge/discharge means (15). A machine as in claim 2, wherein the cage (7) is provided at least internally of the frusto-conical section (8) with a conveyor rib (10), angled in relation to the cone generators of the cage and extending from the charge/discharge port (9) for the entire axial length of the frusto-conical section (8) through a helical path of which the pitch decreases as the distance from the port (9) increases in such a way as to ensure a continuous and uniform propulsion of the items (4) at a substantially constant flow. A machine as in claim 2, wherein the cage (7) is provided at least internally of the frusto-conical section (8) with a plurality of helical conveyor ribs, of which the height, measured from the internal wall of the cage (7) with which they are associated and of which they occupy the entire axial length, decreases proportionately with the increase in longitudinal distance from the charge/discharge port (9) toward the end baffle (17) of the cage, in such a way that the surface area of the conveyor ribs (10) offered to the items (4) remains constant along the entire length of the cage, thereby ensuring a continuous and uniform propulsion of the items (4) at a substantially constant flow.

Inventors: ZUCCHINI GUIDO, ZUCCHINI, GUIDO
Applicants: AMA UNIVERSAL SPA, AMA UNIVERSAL S.P.A.
Application year: 1990
Main classification: B08B3
IPC codes: B08B3