EP2213778A1

EP2213778A1 - Manufacturing process of a ballasted tub for front loading laundry treating machines and tub so manufactured

Info

Publication number: EP2213778A1
Application number: EP09425033A
Authority: EP
Inventors: Roberto Quattrin; Silvano Venuti
Original assignee: Rosa Plast SpA
Current assignee: Rosa Plast SpA
Priority date: 2009-02-02
Filing date: 2009-02-02
Publication date: 2010-08-04

Abstract

The present invention refers to a manufacturing process of a ballasted tub for use in connection with oscillating assemblies of laundry treating machines, such as clothes washing machines, combined washing and drying machines and clothes drying machines, of the front-loading kind. The present invention further refers to a tub manufactured with such process. The manufacturing process according to the present invention is characterized in that it comprises the following steps of:
a) forming a first and a second body (2, 3), each one of them comprising a substantially cylindrical drum-like side portion (4, 9), in which a first end region (5, 10) thereof is at least partly closed by a wall (6, 11) that extends transversally relative to the extension plane of said drum-like side portion (4, 9), and a second end region (8, 17) thereof is on the contrary open;
b) forming a disc-shaped member (14, 14', 14");
c) associating said disc-shaped member (14, 14', 14") to said first end region (5) of the first tub body (2) so that, between said disc-shaped member (14, 14', 14") and said wall (6), there is created at least one cavity (15, 15');
d) providing balancing means (25) and arranging them so that, upon conclusion of the preceding step c), said balancing means (25) are at least partly housed within said at least one cavity (15, 15').

Claimed is also a tub (1) made in accordance with said manufacturing process.

Description

The present invention refers to a manufacturing process of a ballasted tub for use in connection with oscillating assemblies of laundry treating machines for the treatment of clothes in general, such as clothes washing machines, combined washing and drying machines and clothes drying machines, of the front-loading kind. The present invention further refers to a tub manufactured with such process.
Laundry treating machines of the above-noted kind are largely known to comprise a so-called "oscillating" assembly, including a tub adapted to be mounted within an outer casing by means of appropriate vibration-damping devices, a clothes-holding drum rotatably mounted within said tub, motor means for rotatably driving the drum, and a system of masses intended to balance the oscillating movement of the oscillating assembly. Such system of masses - commonly known also as "counterweights" in the art - is generally formed of a plurality of blocks made of concrete, or any other suitable material with a high specific weight, and associated to the tub in a variety of manners.
According to current processes generally used in the art, these masses, or counterweights, used to balance the oscillating assembly of laundry treating machines may be manufactured, i.e. moulded separately from or independently of the tubs which they are intended to be applied to, in that such masses are first poured into and then allowed to set inside a container, generally of a polymeric material, which is provided with appropriate mounting means for attaching the resulting counterweight to the body of the tub. An example of an embodiment of this kind is disclosed in FR 2 789 620 . A drawback that is generally encountered with this kind of counterweights, however, lies in the fact that mounting them onto the tub makes it necessary for the tubs to be provided with appropriate superstructures enabling the attachment means to be received therein and the counterweight to be duly and firmly coupled to the tub. Now, forming such superstructures on the tub body implies a considerable extent of construction and design complications in the process of making and fabricating the tub, while it would be most desirable and preferable for such complications to be simply avoided. Furthermore, the need practically arises for the geometrical, i.e. shape and size specifications of the counterweight to be duly modified for adaptation to the particular model and type of laundry treating machine in which the tub is due to be mounted, actually, and this can be readily appreciated to imply a considerable waste of resources in general.
Disclosed in the European patent application EP 1 522 624 is a solution calling for the balancing masses of the oscillating assembly to be accommodated into appropriate cavities provided in the tub. In the case of a top-loading clothes washing machine, the counterweights are housed in appropriate containers that are associated to a drum-like hollow cylinder so as to close the front and rear end portions thereof and convert in this way the cylinder into an actual tub. In the case of a front-loading clothes washing machine, the disclosure in EP 1 522 624 suggests that the counterweight be formed by casting concrete into a double-wall jacket extending over the entire side cylinder forming the tub, so that the body of such tub is enabled to also act as the counterweight for the oscillating assembly.
The solutions and the related embodiments disclosed in EP 1 522 624 call for the containers receiving the concrete mix used to provide the balancing masses for the oscillating assembly to be manufactured by a blow moulding technique using a polymeric material, or by moulding two shell-halves that are then joined together, filled with concrete mix, and finally associated to the side cylinder so as to form a ballasted tub. Anyway, these solutions turn practically out as being particularly disadvantageous, since they do not ensure any adequate strength of the tub for the latter to be able to reliably withstand the kind of stresses it is subject to during the normal operation of the machine. Under such normal operating conditions of the machine, in fact, the centrifugal force that is generated by the rotary motion of the rotating drum mounted within the tub, and which normally acts upon the mass of clothes to be treated being held in the same drum, is such as to bring about a state of stress and a corresponding strain on the tub. In particular, such stress and the resulting strain induced upon the tub are certainly greater, i.e. stronger in those regions of the tub, in which there are located the motion transmission members used to rotatably drive the drum contained therein, i.e. in at least one of the portions that close the cylindrical side wall of the tub on the rear thereof. Neither techniques described in EP 1 522 624 for obtaining such portions of the tub nor the means cited in said publication in view of securing such portions to the cylindrical side wall of the tub contemplate forming or providing any reinforcement structure, which is effective enough as to impart the kind of structural strength needed to withstand the stresses which the tub is subject to when the laundry treating machine is operating. Therefore, tubs of the kind disclosed and proposed in EP 1 522 624 may in the course of time be disadvantageously subject to liquid leakages, or mismatching of parts, in the region thereof where the above-cited drum driving members are coupled with the body of the tub. Moreover, the blow-moulding technique does not lend itself to forming appropriate reinforcement structures at those portions of the tub body, which are subject to a greater extent of stresses, i.e. undergo greater strain.
Therefore, it is a main object of the present invention to provide a manufacturing process of a ballasted tub, as well as a tub manufactured according to such process, for application to the so-called oscillating assemblies of machines of the front-loading kind for the treatment of clothes, wherein both such processes and the tubs manufactured in accordance therewith are effective in doing away with the drawbacks and disadvantages that are typical of prior-art manufacturing processes and ballasted tubs, as noted above.
Within this general aim, it is a purpose of the present invention to provide a manufacturing process of a ballasted tub of the above-cited kind, which is effective in enabling the usage of raw materials needed for manufacturing the tub to be reduced.
A further purpose of the present invention is to provide a manufacturing process of a ballasted tub for application to the so-called oscillating assemblies of front-loading laundry treating machines, i.e. machines of the front-loading kind for the treatment of clothes, which is simple to carry out under reduced cycle times as compared with currently used prior-art processes, said process according to the present invention enabling the tub to be quickly assembled.
Another purpose of the present invention is to provide a manufacturing process of a ballasted tub, which is effective in doing away with any need whatsoever for superstructures to be provided, as they are usually required to allow the balancing masses of the oscillating assembly to be attached and secured thereto, while allowing for a general simplification in the structure and construction of the same tub.
Yet another purpose of the present invention is to provide a tub for application to the so-called oscillating assemblies of laundry treating machines of the front-loading kind, which effectively withstands the stresses it is due to be subject to during the normal operation of the machine, wherein such tub further has a structure that is more rigid than the one of prior-art tubs in general, although it is manufactured using a smaller amount of raw material.
Still another, equally important purpose of the present invention is to provide a tub, whose structural properties are such as to allow for a shorter distance to be maintained between the cylindrical side wall, or periphery, of the rotating drum inside the tub and the cylindrical side wall, or periphery, of the same tub, thereby enabling a greater volume, i.e. loading capacity of the drum to be provided for a same overall dimension of the oscillating assembly.
A further purpose of the present invention is also to provide a tub for application to the so-called oscillating assemblies of laundry treating machines of the front-loading kind, which allows for an improved, more rational layout and general arrangement of the functional and operating parts of the machine, such as for instance a condenser and a portion of the drying-air circuit in such laundry treating machine as a washer-drier.
According to the present invention, all these aims reached in a manufacturing process of a ballasted tub, as well as a tub manufactured according to such process, for application to the so-called oscillating assemblies of machines of the front-loading kind for the treatment of clothes, which incorporate the features and characteristics as defined and recited in the appended claims.
Features and advantages of the present invention will anyway be more readily understood from the description that is given below by way of non-limiting example with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a tub made in accordance with the present invention;
Figure 2 is a cross-sectional view of the tub shown in Figure 1;
Figures 3a and 3b are a rear perspective view and a front perspective view, respectively, of a disc-shaped member;
Figures 4a and 4b are a rear perspective view and a front perspective view, respectively, of balancing means;
Figures 5a and 5b are a rear perspective view and a front perspective view, respectively, of a first body of the tub according to the present invention;
Figure 6 is a perspective view of a first modified embodiment of the disc-shaped member;
Figures 6a and 6b are a rear perspective view and a front perspective view, respectively, of a second modified embodiment of the disc-shaped member;
Figure 7 is a schematical view of a possible arrangement of the balancing means on a disc-shaped member;
Figure 8 is a cross-sectional view of a detail of a possible coupling of motor means, provided coaxially to the axis of rotation of a drum, to the balancing means;
Figure 9 is a rear, partially cross-sectional view of an example of embodiment of an oscillating assembly for a combined clothes washing and drying machine provided with a condenser member and a drying-air conduit that are partly housed within the body of the tub.

With reference to Figures 1, 2 and 5b, when made in accordance with the present invention a tub 1 for oscillating assemblies of front-loading laundry treating machines in general comprises a first body 2 that forms a rear portion of the tub 1, and a second body 3 that forms the front portion of the tub 1. The first body 2 comprises a drum-like side wall 4 that has a substantially cylindrical shape and is provided with a first end region 5, which is partially closed by a wall 6 formed integrally, i.e. as a unitary single-piece construction with the cylindrical side wall 4 and extends transversally relative to the latter. The wall 6 forms the bottom of the tub 1 and is provided with an aperture 7 adapted to receive and accommodate a drive shaft, which is intended to transmit motion to a drum rotatably mounted within the tub 1, and is adapted to receive and hold the laundry items to be treated therein. The cylindrical side wall 4 of the first body 2 comprises a second end region 8, which is however open.
In turn, even the second body 3 of the tub 1 comprises a second drum-like side wall 9 that has a substantially cylindrical shape and is provided with a first end region 10 of its own. This end region 10 is in turn provided with a wall 11 formed integrally, i.e. as a unitary single-piece construction with the cylindrical side wall 9, wherein such wall 11 extends transversally relative to the plane of extension of said cylindrical side wall 9 and includes an aperture 12, which practically forms a loading opening provided to allow a user to gain access into the inner cavity of a clothes-holding drum in view of placing the laundry items to be treated thereinto. A second open end region 17 is provided on the cylindrical side wall 9 for it to be associated to the second end region of the first body 2, so as to form a container 13 in a substantially cylindrical shape. The bottom wall 6 of this container 13 is further reinforced through the provision of a disc-shaped member 14 that is associated to the wall 6 from outside, i.e. from the opposite side relative to the one where the drum-holding cavity formed by the union of the above-mentioned pair of bodies 2, 3 lies.
As can be noticed in the illustration of Figure 2, the contour of the bottom wall 6 of the tub 1 and the corresponding contour of the disc-shaped member 14 are such that, when said disc-shaped member 14 is associated to the wall 6, the resulting association brings about, i.e. forms a cavity 15 delimited by the outer surface 18 (Figure 5a) of the bottom wall 6 and the inner surface 19 (Figure 3b) of the disc-shaped member 14. Even this disc-shaped member 14 is on the other hand provided with an aperture 16, which is so arranged as to lie coaxially with the aperture 7 provided in the wall 6 of the body 2. The aperture 16 performs the same duty, i.e. is used to the same purpose as the afore-described aperture 7. The axis X, which is common to both such apertures 7 and 16, coincides with the axis of rotation of the drum that is mounted rotatably inside the tub 1. A housing structure 20, preferably provided by fitting a metal hub into the body of the disc-shaped member 14, protrudes from the inner surface 19 thereof so as to create an accommodation adapted to receive one or more bearings for the rotary motion of a drive shaft. The protruding end portion 24 of this housing structure 20 is received into the aperture 7 provided in the bottom wall 6 of the tub 1, as this is best shown in Figure 2.
The association of the disc-shaped member 14 with the first body 2 of the tub 1 may be made by joining the two parts not only along the edge that defines the aperture 7, but also along the outermost peripheral edge of the disc-shaped member 14, and may be further strengthened by properly joining a plurality of projections 26, which may be provided either solely on the outer surface 18 of the bottom wall 6 of the tub body 2, as this is best illustrated in Figure 5a, or solely on the inner surface 19 of the disc-shaped member 14, or, again, in corresponding positions on both said surfaces 18 and 19, wherein these projections 26 should in this case be provided with conjugate surfaces to allow them to be mutually coupled by the matching of shapes. As this shall be described in greater detail further on, these projecting members 26 have additionally the purpose of enabling a counterweight to be positioned such that this mass, due to the disc-shaped member 14 being then joined to the bottom wall 6 in the above-described manner, becomes firmly joined, i.e. practically integral with these two parts, thereby creating a single structure.
Represented in the illustration of Figure 6 there is a first modified embodiment 14' of the disc-shaped member. In a departure from what has been described and illustrated above with reference to Figures 1, 2, 3a and 3b, the disc-shaped member 14' according to this first modified embodiment is no longer provided with an inner surface 19 that is continuous and free from any further aperture other than the aperture 16 provided for the motion-transmission, i.e. driving members as described hereinbefore. Such disc-shaped member 14' is rather formed of a ring-shaped portion 21 provided with a plurality of spokes 22 converging towards the aperture 16' and spaced from each other by the interposition of apertures 23 in a substantially triangular or trapezoidal shape, so as to form a radiate arrangement. Even in this first modified embodiment there is anyway provided a housing structure 20' that protrudes from the inner surface 19' of the disc-shaped member 14' so as to create an accommodation adapted to receive one or more bearings on an appropriate, preferably metal support for a driving shaft to be able to rotate therein. The protruding end portion 24' of this housing structure 20' is again received into the aperture 7 provided in the bottom wall 6 of the tub 1.
According to this first modified embodiment of the disc-shaped member 14', as illustrated in Figure 6, associating this disc-shaped member 14' with the first end region 5 of the first body 2 of the tub 1 causes a plurality of open cavities 15' to be formed, which can be noticed to extend between the outer surface 18 (Figure 5a) of the bottom wall 6 of the tub 1 and the inner wall 19' of the disc-shaped member 14'.
Represented in the illustrations of Figures 6a and 6b there is a second modified embodiment 14" of the disc-shaped member as viewed from the rear side (Figure 6a) and the front side (Figure 6b) thereof. In the front-view representation there can also be seen a balancing mass 25 in the condition in which it is mounted on to the disc-shaped member 14". When the disc-shaped member 14" is duly mounted on to the body 2 of the tub, said balancing mass 25 will be accommodated in the cavity 15 that forms between the outer surface 18 of the bottom wall 6 of the tub and the inner surface 19" of the disc-shaped member 14". For reasons of greater illustrative simplicity, the various details and items that this second modified embodiment of the disc-shaped member 14" shares with the embodiments of the disc-shaped member 14 and 14', as they have been described hereinbefore with reference to Figures 1, 2, 3a, 3b and 6, are indicated in Figures 6a and 6b using the same reference numerals. As far as the description of these common items and details is concerned, reference should therefore be made to what has been set forth afore with reference to Figures 1, 2, 3a, 3b and 6.
The disc-shaped member 14" comprises a plurality of pockets 38 provided all around the aperture 16. These pockets 38 are defined by a plurality of walls 40 arranged radially around the aperture 16 on the rear side of the disc-shaped member 14", i.e. on the side lying opposite to the one that is associated to the rear body 2 of the tub 1. Between two adjacent ones of these walls 40 there are formed cavities 39 having a bottom end portion that is closed by a portion of the inner surface 19"; in other words, these cavities 39 are such that the disc-shaped member 14" ultimately features an imperforated ring-shaped wall 41, which therefore is free from through-apertures, and which extends all around the aperture 16. In the illustration of Figure 6b, there can be noticed how these cavities 39 of the pockets 38 are closed at the bottom thereof and said ring-shaped surface 41 is imperforated and, as a result, free from any possible structurally weakening element, actually.
The above-mentioned pockets 38 are provided in view of lightening the structure of the disc-shaped member 14" in the region extending immediately around the housing structure 20, thereby advantageously saving a significant amount of preferably polymeric material, while still ensuring an adequate structural strength of the tub 1. Even the cycle time required to manufacture the disc-shaped member 14" is shorter than the one required to manufacture the afore-described disc-shaped member 14 made in accordance with the embodiment represented in Figures 1, 2, 3a, 3b.
Even this modified embodiment of the disc-shaped member 14" may be provided, in the inner surface 19" of the ring-shaped wall 41, with a plurality of projections 26 in the same way as this has been described with reference to the disc-shaped member 14. As this shall be described in greater below, these projections 26 are effective in enabling a balancing mass 25 to be secured thereto.
Within the cavities 15 and 15' there are located balancing means 25 adapted to dampen the oscillations, i.e. the vibrations which the tub 1 - and, as a result, the whole oscillating assembly of which the tub 1 is a part - is subject to when the laundry treating machine comprising said tub 1 is operating. These balancing means 25 are comprised of a mass of material having a high specific weight (typically greater than or equal to 2.6 kg/dm³), such as for instance cement, concrete or compounds thereof containing metal materials. As this shall be described in greater detail further on, the above-cited balancing means 25 may be placed into the cavities 15 and 15' either in a solid form or, if the material which they are made of allows it, in a liquid form. In particular, when a disc-shaped member 14' made and shaped according to the first modified embodiment shown in Figure 6 is used as the disc-shaped member associated to the inventive tub, the balancing means 25 must necessarily be in a solid form and may be accommodated in the cavities 15' either completely or in a way in which they just partly protrude from the apertures 23 in the rear portion of the tub 1. When so housed in the cavities 15, 15', the balancing means 25 will work not only as balancing masses to oppose and dampen the vibrations of the oscillating assembly which the tub 1 is a part of, but also as a reinforcement structure for those portions of the tub 1, which are more subject to stresses during the operation of the machine, in which the same tub 1 is incorporated. If desired or considered more appropriate, in order to further strengthen the rear portion of the tub, and make it still more rigid, on the inner surface 19, 19', 19" of the disc-shaped member 14, 14', 14" and/or the outer surface 18 of the bottom wall 6 of the tub body 2 there may be formed stiffening ribs 32.
With reference to Figure 2, second balancing means 37 may be provided on the front portion of the tub 1 in the vicinity of the aperture 12 provided in the second tub body 3. Attaching said second balancing means 37 on to the body 3 of the tub 1 is done using such methods and means as they are largely known as such in the art, such as for instance screws.
Illustrated in Figure 7 is a possible configuration of the balancing means 25, as arranged in the cavity 15. For reasons of greater illustrative simplicity, solely shown in this representation are the mass 25 and a disc-shaped member, which may be made according to the embodiments that are indicated with the reference numerals 14 and 14' in Figures 1, 2, 3a, 3b and 6a, 6b, respectively. As this can be seen in the representation of Figure 7, this mass 25 fills up the cavity 15 only partially to thereby create a discontinuity 27 situated in correspondence to the motor means 28 provided to rotatably drive a drum adapted to receive and hold the laundry items to be treated, and rotatably mounted inside the tub 1 to that purpose, wherein such motor means are schematically represented by a circle in the Figure. The balancing means 25 are further provided with bores 29, through which the projections 26 represented in Figure 5a are able to pass.
Figure 8 illustrates a schematical, cross-sectional representation of a tub 1, in which the balancing means 25 act as a support for motor means 28 provided coaxially with the axis of rotation X of the drum mounted rotatably within the tub 1 to receive and hold the laundry items to be treated. Securing the motor 28, and in particular the stator portion thereof, to the balancing means or, more generally, to the tub is done with the aid of screw means 29 passing through the wall of the disc-shaped member 14, 14" and accommodated into blind bores 31 provided in the balancing mass 25. Also to be seen in Figure 8 is the motion-transmission, i.e. drive shaft 30 for a drum to be attached thereto by a shrink-fitting or similar process. With a configuration like this one, thanks to the high rigidity and strength imparted to the rear portion of the tub 1 by the provision of the counterweight 25 and the stator portion of the drive motor 28, the possibility arises for a strain control to be effectively and positively ensured, thereby preventing the distance (gap) between the rotor and the stator of the drive motor 28 from being altered to affect the efficiency or even the ability of the same motor 28 to operate.
Represented in Figure 9 is a so-called oscillating assembly including a tub 1 made and provided according to the present invention. This tub 1 is fitted out with some functional component parts as needed to enable a laundry treating machine to perform a laundry treatment process. In particular, the tub 1 is capable of being mounted in a so-called washer-drier, i.e. a combined clothes washing and drying machine, since it is provided with a condenser 33 of the water-spray cooled type housed within a conduit 34 in which there is circulated a flow of clothes drying air by a fan 35 that is driven via a set of pulleys 36. The most prominent feature of the oscillating assembly illustrated in Figure 9 lies in the fact that part of both the condenser 33 and the drying-air conduit 34 is housed within the cavity 15 being defined between the disc-shaped member 14, 14" and the outer surface 18 of the bottom wall 6 of the tub body 2. In this way the possibility practically arises for the portions of functional and operating parts protruding from the outer contour of the tub 1 and, as a result, the overall size and space requirements of the entire oscillating assembly to be reduced to a considerable extent. In addition, in the case that the operation of the machine for the treatment of laundry items includes or calls for the laundry items being treated to undergo a spin-drying cycle under hot conditions, no need arises, actually, for the preferably polymeric material, which the tub is made of, to possess any particularly high mechanical strength or performance ability under high-temperature conditions, thereby enabling lower-performance materials and, therefore, less expensive materials to be used, since the structural strength of the bottom of the tub is in fact ensured by the provision of the counterweight.
As far as the process for manufacturing the ballasted tub 1 is concerned, this includes forming a first and a second body 2, 3, each one of them comprising a substantially cylindrical drum-like side portion 4, 9, in which a first end region 5, 10 thereof is at least partly closed by a wall 6, 11 that extends transversally relative to the extension plane of said drum-like side portion 4, 9. Each such cylindrical drum-like side portion 4, 9 further comprises a second end region 8, 17, which is on the contrary open. The process according to the present invention further includes forming a disc-shaped member 14, 14', 14", and associating this member to said first end region 5 of the first body 2 of the tub 1 so that, between the disc-shaped member 14 and the bottom wall 6 of the tub body 2, there are created one or more cavities 15, 15'. Balancing means 25 are then provided and arranged so that, upon conclusion of the preceding step of associating the disc-shaped member 14, 14', 14" to the tub body 2, said balancing means 25 turn out as being at least partly housed within said one or more cavities 15, 15'.
The operation for fitting the balancing means 25 into the cavities 15, 15' and accommodating them therewithin can be performed in a variety of ways. For instance, the mass 25 can be cast into the whole cavity 15, or a part thereof, in a liquid state thereof after that the disc-shaped member 14, 14" and the body 2 of the tub 1 have been associated with each other, and then allowed to set, i.e. become solid there. Alternatively, with reference to Figures 4a, 4b, 6 and 6a, 6b, the mass 25 in a solid form may be arranged and accommodated between the disc-shaped member 14, 14', 14" and the body 2 of the tub 1 prior to these part being associated to each other. In this case, the mass 25 can be associated, e.g. by bonding, to either the inner surface 19, 19', 19" of the disc-shaped member 14, 14', 14" or the outer surface 18 of the bottom wall 6 of the tub body 2, so as to prevent voids from forming between the counterweight 25 and the disc-shaped member 14, 14', 14" or the bottom wall 6 of the tub body 2.
In the solid balancing mass 25 there may be provided bores 29 for the projections 26 formed on the disc-shaped member 14, 14' and/or the bottom wall 6 of the tub body 2 to be able to be fitted therethrough. These projecting members 26 may be provided in any appropriate shape in view of creating a structure suitable to enable a balancing mass 25 to be positioned such that it - following the disc-shaped member 14, 14" having been joined to the bottom wall 6 - becomes practically integral with both said disc-shaped member and said bottom wall to create a single structure therewith.
The process for manufacturing a tub 1 according to the present invention, although being capable of being carried out by using either metal materials or polymeric materials in an equally acceptable manner, is preferably and advantageously carried out by using materials of a polymeric type.
Fully apparent from the above description is therefore the ability of the present invention to effectively reach the aims and advantages cited afore by in fact providing a process for manufacturing a ballasted tub that is able to withstand the stresses developing during the operation of a laundry treating machine. The tub is advantageously capable of being fabricated with the use of a smaller amount of raw materials as compared with prior-art tubs of the considered kind, and is therefore featuring a lower weight than the tubs used and known in the art hitherto. Furthermore, this process is such as to enable the geometry of the tub to be simplified by doing away with the usually provided structures for the attachment of the counterweights, which are generally known as to be likely to turn into possible sources of structural failure of the tub. A further advantage of the tubs for use in laundry treating machines of the front-loading type made according to the present invention derives from the fact that the distance between the cylindrical side portion of the tub and the cylindrical side portion of the rotating drum mounted within the same tub can be reduced as compared to the one generally needed in prior-art tub and drum assemblies. In other words, this practically means that drums having a greater volume, i.e. capacity may be provided while keeping the the overall outer size of the oscillating assembly unaltered or, the other way round, the overall outer size of the oscillating assembly may be reduced while keeping the inner volume, i.e. loading capacity of the drum unaltered.
A tub made according to the present invention further enables the distribution of the balancing masses within the body of the same tub to be appropriately sized and selected so as to most effectively cope with the distribution of the weights or loads on the oscillating assembly, without any need arising for the overall outer size of such assembly to be increased.
Still another advantage offered by a tub made according to the present invention lies in the fact that the mass used to act as a counterweight, i.e. to balancing purposes, may at the same time be used as a support for the motor means provided to drive the rotating drum to be anchored thereto by arranging them along the axis of rotation of the same drum. In addition, the counterweight will not only work to ensure the usual balancing duty thereof to balance the oscillating assembly, but will also perform as a reinforcement structure for those portions of the tub body, which are subject to a greater extent of stresses, i.e. tend to undergo greater strain in operation. The usual reinforcement ribs that have traditionally been used on the rear portion of the tub shall not be needed in a tub made according to the present invention any longer, thereby achieving the advantageous effect of lightening the construction of the tub and reducing the amount of material needed to produce it.
It shall be appreciated that the materials used, as well as the shape and the sizing of the various parts of the inventive tub assembly may each time be selected so as to more appropriately meet the particular requirements or suit the particular application.
It shall further be appreciated that the various elements forming the object of and being part of the present invention shall certainly not be solely embodied in the manners that has been described and illustrated hereinbefore, but can rather be implemented in many other embodiments - although not specifically illustrated here - without departing from the scope of the present invention.

Claims

Manufacturing process of a ballasted tub (1) for use in connection with the oscillating assemblies of laundry treating machines of the front-loading kind, characterized in that it comprises the following steps of:
a) forming a first and a second body (2, 3), each one of them comprising a substantially cylindrical drum-like side portion (4, 9), in which a first end region (5, 10) thereof is at least partly closed by a wall (6, 11) that extends transversally relative to the extension plane of said drum-like side portion (4, 9), and a second end region (8, 17) thereof is on the contrary open;

b) forming a disc-shaped member (14, 14', 14");

c) associating said disc-shaped member (14, 14', 14") to said first end region (5) of the first tub body (2) so that, between said disc-shaped member (14, 14', 14") and said wall (6), there is created at least one cavity (15, 15');

d) providing balancing means (25) and arranging them so that, upon conclusion of the preceding step c), said balancing means (25) are at least partly housed within said at least one cavity (15, 15').
Manufacturing process according to claim 1, wherein said balancing means (25) are comprised of a mass of material having a specific weight that is greater than or equal to 2.6 kg/dm³.
Manufacturing process according to claim 1 or 2, wherein the step d) is carried out following the step c) by pouring or casting said balancing means (25) into said at least one cavity (15) in a liquid state thereof.
Manufacturing process according to any of the claims 1 to 3, wherein the step d) calls for said balancing means (25) to be associated to said wall (6) of the first tub body (2) or to said disc-shaped member (14, 14', 14"), and said step c) is carried out following the step d).
Ballasted tub (1) for use in connection with oscillating assemblies of laundry treating machines of the front-loading kind and manufactured with the process according to any of the claims 1 to 4, comprising a pair of bodies (2, 3) that are mutually associated so as to form a substantially cylindrical container (13) including a rear bottom wall (6) and a front loading aperture (12), said tub (1) further comprising a disc-shaped member (14, 14', 14") associated to said rear bottom wall (6) so as to form at least one cavity (15, 15') created between said disc-shaped member (14, 14', 14") and said wall (6), characterized in that within said at least one cavity (15, 15') there are housed balancing means (25) adapted to dampen the vibrations of said oscillating assembly.
Tub (1) according to claim 5, wherein said balancing means (25) are comprised of a mass of material having a specific weight that is greater than or equal to 2.6 kg/dm³.
Tub (1) according to claim 6, wherein said mass fills up said at least one cavity (15, 15') only partially.
Tub (1) according to any of the claims 5 to 7, wherein said tub (1) is made of a polymeric material.
Tub (1) according to any of the claims 5 to 8, wherein said disc-shaped member (14, 14', 14") and/or said rear bottom wall (6) comprise reinforcement ribs (32).
Tub (1) according to any of the claims 5 to 9, wherein said disc-shaped member (14, 14") and/or said rear bottom wall (6) comprise projecting members (26) for connecting said disc-shaped member (14, 14") to said first tub body (2).
Tub (1) according to any of the claims 5 to 10, wherein said rear bottom wall (6) and said disc-shaped member (14, 14', 14") comprise coaxial apertures (7, 16) adapted to receive and accommodate a motion-transmission shaft (30) of drive motor means (28), and said balancing means (25) comprise support surfaces (31) for said drive motor means (28).
Tub (1) according to any of the claims 5 to 11, wherein said disc-shaped member (14") comprises a plurality of pocket-like recesses (38) provided around a through-aperture (16), said pocket-like recesses (38) being defined by cavities (39) having a closed bottom end portion.
Laundry treating machine comprising a ballasted tub (1) according to any of the claims 5 to 12.
Laundry treating machine according to claim 13, comprising a drum adapted to receive and hold the laundry items to be treated and rotatably mounted within said tub (1), and further comprising drive motor means (28) associated to said balancing means (25) and shrink-fitted onto the rotating shaft or axis of rotation (X) of said drum.
Laundry treating machine according to claim 13 or 14, wherein at least a functional part (33, 34) for the operating cycle of said machine is at least partially housed within said at least one cavity (15, 15').