Moldable pipe

Abstract

A malleable tube (10) provided with two rolling bearings (20) arranged along a respective axis of rotation (A), wherein a spacer (40) is inserted between the two rolling bearings (20) to provide structural stiffness to the malleable tube (10); and a cylindrical retaining sleeve (5) formed around the two rolling bearings (29) and the spacer (40), wherein two metal bushings (60) are inserted between the cylindrical sleeve (50) and the two rolling bearings (20) to be formed together with the cylindrical sleeve (50).

Description

Technical Field of the InventionThe present invention relates to a moldable tube.The present invention relates in particular to a moldable tube for washing machine tubs, to which explicit reference is made in the following description without losing the general character of the invention.Prior ArtTub moldable pipes are designed to form an integral part of these tubs to facilitate the washer assembly operations and must support the rotating component of the tub.The moldable pipes for washing machines of the known type generally comprisetwo rolling bearings arranged along an axis of rotation of a washing machine drum;a spacer, generally made of plastic material and having a box-shaped structure, which gives structural rigidity to the tube; anda cylindrical holding sleeve made of plastic material which is formed by co-molding around the two bearings and the spacer.In the moldable tubes of the type described above, the two rolling bearings are directly attached to the opposite ends of the spacer and are also embedded in the cylindrical retaining sleeve. Moreover, the spacer, apart from giving structural rigidity to the sleeve, has in particular the main function of keeping the two rolling bearings at a certain axial distance from each other, these being provided with respective circumferential outer grooves which, during co-moulding of the sleeve, are filled with the same material as the sleeve, in order to increase the axial and radial clamping between the sleeve and said rolling bearings. In other words, the two rolling bearings form an integral part of the cylindrical retaining sleeve and it is practically impossible to service them in the event of a malfunction, since in the most critical cases the entire tub must be replaced, since it also forms an integral part of the moldable tube.Due to the fact that the two rolling bearings must be designed in an angular manner with respect to the cylindrical sleeve, it is furthermore necessary to provide circumferential outer grooves which, since they must be machined on the steel of the rolling bearings, cause additional production costs.SUMMARY OF THE INVENTIONThe object of the present invention is to provide a moldable tube which, while maintaining the advantages of the known moldable tubes, namely the possible formation of iron oxides due to the presence of water vapor and condensate, which are typically present in most washing cycles, is in any case not subject to the aforementioned disadvantages, i.e. enables rapid and cost-effective maintenance if required.According to the present invention there is provided a moldable tube having the features set forth in the appended claims.Brief Description of the DrawingsThe invention will now be described with reference to the accompanying drawings which show a non-limiting embodiment of the invention, in which:FIG. 1 is an axial sectional view of a preferred embodiment of the moldable tube according to the present invention; andFIG. 2 is a perspective view of a detail of the moldable tube of FIG. 1.DETAILED DESCRIPTIONWith reference to the attached figures, 10 indicates overall a tube which is preferably, but not necessarily, moldable with washing machine tubs or other fixed structural elements and is intended to support, when molded with a tub, a washing machine drum or other part rotating with respect to said structural element.For simplicity, in the following description, reference will be made specifically to the case in which the tube 10 is formed together with a tub of a washing machine, schematically shown in the figure and denoted 11, to form a single component with said tub 11, so that the production time of the washing machine is reduced.The tube 10 comprises:two rolling bearings 20 arranged along an axis of rotation A of a washing machine drum (known and not shown);a spacer 40 axially interposed between the two rolling bearings 20 and made of polymeric material; anda cylindrical retaining sleeve 50, which, again with a view to optimizing production times and costs, is preferably made of plastic material by co-molding around the two bearings 20 and the spacer 40.Each rolling bearing 20 comprises a respective inner ring 21 and a respective outer ring 22, between which a respective row 23 of rolling elements, in particular balls, is interposed, in order to allow the rotation of the inner ring 21 with respect to the corresponding outer ring 22.The spacer 40 is made of plastic, preferably, but not necessarily, fiberglass reinforced polypropylene, and when both the sleeve 50 and the spacer 40 are made of the same plastic, the process of co-molding the former to the latter may also result in intrinsic bonding of a surface portion of the spacer 40 and the sleeve 50, thereby making the entire structure of the tube 10 even stiffer. According to embodiments not shown here, but which can easily be derived from those described here, the spacer 40 can also be made of glass fibre reinforced polybutylene terephthalate or in any case from similar plastics suitable for being injected in a semi-liquid state into a mould in order to give the spacer 40 a structure which will be described below.The spacer 40 has a box-shaped structure and comprises an inner cylindrical body 41, a shaped outer body 42 coaxial with the body 41, and an intermediate radial partition wall 43 arranged transversely to the axis A and extending radially from the body 41 to the body 42 in a substantially central position along the spacer 40 so that the body 41 is firmly connected to the body 42. The bodies 41 and 42 define, with the partition 43, two annular spaces 44 designed so that the total weight of the spacer 40 is less than the weight of a solid spacer, ensuring the same rigidity characteristics. The spacer 3 also comprises a plurality of axial ribs 45 arranged inside the spaces 44 parallel to the axis A and around the axis A, made in one piece from the same material as the partition wall 43 and the bodies 41 and 42 and each having an axial external profile 451.The shaped outer body 42 comprises two axially opposite cylindrical ends 421 which extend axially beyond the inner cylindrical body 41 and also beyond the outer axial profiles 451 of the axial ribs 45 to define with said axial ribs 45, more precisely with said axial profiles 451, respective cylindrical locating seats 423, the shapes of which are arranged substantially flush with the cylindrical body 41 and are inserted axially with respect to the opposite cylindrical ends 421.The injection-moldable tube 10 also comprises two metallic bushes 60 inserted between the cylindrical sleeve 50 and the two rolling bearings 20 and directly molded with the cylindrical sleeve 50. In particular, the bushes 60 are formed externally, although only partially, in the seats 423 of the spacer 40, with the cylindrical sleeve 50 along the part not engaged with the spacer 40, and are provided with a respective internal locating seat 61 for a respective rolling bearing 20: each seat 61 houses in its interior a respective bearing 20 substantially radially separated from the cylindrical sleeve 50, and since each locating seat 61 remains axially open towards the outside of the tube 10 even after being formed with the trough 11, the respective bush 60 enables the rolling bearings 20 to be pulled out of the tube 10, They are also partially inserted between the rolling bearings 20 and the spacer 40, whereby the tube 10 can be pulled out of the tube even after the forming with the tub 1.Since the bushes 60 must in any case ensure the assembly and positioning of the rolling bearings 20, i.e. both axially abut the spacer 40 and must be firmly fixed in the sleeve 50, they comprise both respective gripping elements 62 located on the outside of the locating seats 61 and coupled to the sleeve 50, and respective axial engagement and positioning elements 63 also located on the outside of the locating seats 61 and coupled to a respective opposite end 421 of the spacer 40.According to the preferred embodiment of the tube 10 illustrated in the attached figures and in particular in Figure 2, the gripping elements 62 comprise a plurality of axial outer grooves 621 and an outer circumferential groove 622 formed in an axially intermediate position between the axial outer grooves 621. The grooves 621 each define radial teeth 623 therebetween and are completely filled by the plastic material of the sleeve 50 during the molding of the sleeve 50 with the arrangement formed from the spacer 40, the bushings 60 and the bearings 20, whereby the bushings 60 together with the radial teeth 623 are clamped into the sleeve 50 and a firm connection of the bushings 69 with the sleeve 50 in the circumferential direction is produced. Also, the circumferential outer groove 622, which divides the axial outer grooves 621 and the radial teeth 623 into two substantially similar parts, is completely filled by the plastic material of the sleeve 50 during the molding of the sleeve 50 with the assembly formed by the spacer 40, the bushings 60 and the bearings 20, wherein a radial tooth 51 is formed in the sleeve 50 itself, which, inserted into the outer groove 622, determines a firm connection in the axial direction between the bushings 60 and the sleeve 50.The axial engagement and positioning elements 63 comprise, for each bushing 60, a cylindrical planar surface 631 arranged laterally with respect to the respective axial outer grooves 621 and an axial shoulder 632 defined by said axial outer grooves 621 or, more precisely, by the radial teeth 623. The cylindrical flats 631 are radially inside the axially opposite cylindrical ends 421, while the axial shoulders 632 axially delimiting the corresponding cylindrical flats 631 on one side are axially arranged against the axially opposite cylindrical ends 421, resulting in an exact axial positioning of the two bushes 61 with respect to each other. In particular, and for greater descriptive clarity, each cylindrical end 421 is radially delimited by a respective cylindrical surface 71 substantially defining the respective seat 423 for engagement with the flat surface 631 of the respective bushing 60, and by a respective annular end surface, transverse to the axis A and to the surface 71 for axial abutment with the axial shoulder 632 of the respective bushing 60: the axial distance between the two annular end surfaces 72 determines the axial distance for the arrangement of the bushings 60 and of the rolling bearings 20, the axial positioning of which is further improved by the ribs 45, as will be explained in more detail below.The bushes 60 have an axial width with dimensions corresponding to the axial width of the rolling bearings 20, and the seats 61 also have an axial width with dimensions corresponding to the axial width of the outer rings 22, which are integrally but declutchably fixed in the respective seats 61 which are axially open on both sides: however, when the opening to the outside of the tube 10, as already described, allows the rolling bearings to be pulled out of the tube 10, the opening to the inside of the tube 10 allows the axial positioning of the outer rings 22 against the axial ribs 45, whose shaped outer profiles 451 ensure that the outer rings 22 are indeed positioned against the ribs 45, but the inner rings 21 are axially spaced from the ribs 45 to allow the rotation relative to the inner rings 22.Finally, the cylindrical retaining sleeve 50 comprises, for each metal bush 60, a respective radial retaining edge 52 axially facing the respective cylindrical flat surface 631 with respect to the axially outer grooves 621 and locking the respective metal bush 60 axially against the surface 72 of the respective opposite end 421 of the spacer 40.From the above description it is evident that the bushes 60 provided to the formable tube according to the present invention both allow a precise arrangement of the rolling bearings 20 inside the spacer 40 and in particular separate the outer rings 22 of the rolling bearings 20 from the cylindrical retaining sleeve 50, thus avoiding the latter having to be directly formed on them. In other words, the bushes 60 make the rolling bearings 20 independent of the cylindrical retaining sleeve 50 and make it possible to replace them quickly when necessary, also because of the axially open configuration of their inner seats 61.Although the bushes 60 such as the inner and outer rings 21 and 22 of the rolling bearings 20 are made of metallic material, the formation of the gripping elements 62 and the axial engagement and fixation elements 63 thereon can be done in a much more economical manner and at such a reduced cost that the use of an additional construction element such as the bushes 60 to be coupled to the rolling bearings 20 and the spacer 40 is absolutely competitive.Finally, the grooves 621 and the associated teeth 623 may be formed in a number which is chosen specifically depending on the type of application of the moldable tube 10, and also the outer circumferential groove 622 may be formed with a certain axial width and with an axial position on the inside of the grooves 621 and the associated teeth 623, which in turn depends on the type of application of the moldable tube 10, thus leading to a selection not only substantially free but also certainly greater in the type of the rolling bearing 20 to be used.It is to be understood that the invention is not limited to the embodiment of the moldable tube 10 described and illustrated herein, which is subject to further modifications with respect to embodiments and arrangements of parts, details of construction, and arrangement. The tube 10 is, as already mentioned several times, not only suitable for use in applications which are not associated in the narrower sense with washing machines and the associated tubs, but is also advantageously applicable in other applications in which the tube 10 must be formed together with a fixed support for reasons of simpler production with one for reasons of simpler production and must support a part which rotates relative to the fixed support, while always ensuring sufficient rigidity properties as well as a sealing ability against atmospheric influences such as moisture, water vapor and the like and also facilitating maintenance at a lower production cost in each case.

Claims

A moldable tube (10) comprising: - two rolling bearings (20) arranged along a respective axis of rotation (A); - a spacer (40) interposed between the two rolling bearings (20) to provide the moldable tube (1) with structural rigidity; and - a cylindrical retaining sleeve (50) molded around the two rolling bearings (290) and the spacer (40); the moldable tube (10) being characterized in that it comprises two metal bushes (60) interposed between the cylindrical sleeve (50) and the two rolling bearings (20) and molded with the cylindrical sleeve (50).Moldable tube according to claim 1, characterized in that said two metal bushes (6) each comprise locating seats (61) for each respective rolling bearing (20) and engage the respective opposite ends (421) of the spacer.Moldable tube according to claim 2, characterized in that said two metal bushes (6) comprise axial engagement and positioning means (63), located outside said locating seats (61), and coupled to a respective opposite end (421) of said spacer (40).Moldable tube according to claim 3, characterized in that said two metal bushes (60) comprise gripping means (62) located on the outside of said assembly seats (61) and coupled to said cylindrical sleeve (50).The moldable tube of claim 4, characterized in that the gripping means (62) comprises a plurality of axial outer grooves (621) and a circumferential outer groove (622) formed between the axial outer grooves (621).Moldable sleeve according to claim 5, characterized in that said axial engagement and positioning means (63) comprise a cylindrical flat surface (631) arranged laterally with respect to said axial outer grooves (621) and engaging the respective opposite end (421) of said spacer (40), and an axial shoulder (632) also defined by said axial outer grooves (621) and axially fixed to the respective opposite end (421) of said spacer (40).Moldable tube according to claim 6, characterized in that said cylindrical retaining sleeve (50) comprises, for each metal bushing (60), respective retaining edges (52), which are axially opposite the corresponding cylindrical flat surfaces (631) with respect to said axially outer grooves (621), and lock said corresponding metal bushing (60) axially against the corresponding opposite end (421) of said spacer.

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