Reinforced tub, particularly for laundry washing machines

Abstract: The reinforced tub includes a back wall (3) associated with a tub body (2), the tub body (2) having a substantially cylindrical configuration and including a bottom edge (4). The back wall (3) is associated with the tub body (2) at the bottom edge (4); the tub further includes a stiffening edge (9) formed on said bottom edge (4) of the tub body (2).

Description: The present invention relates to a reinforced tub, particularly for laundry washing machines. The known washing machines are generally provided with a horizontal rotary drum contained in a fixed tub to be loaded with laundry at the front side or from above. Usually, in these machines the tub has a detachable wall for assembling the drum inside the tub and for the possible disassembling of the drum for repairing. The detachable wall is usually secured to the tub body by means of a fastening strip, of truncated-cone shape, that tightens a gasket between the tub body and the back wall, providing a water tight seal during the operation of the machine. A fastening system of the kind described above ensures that the two tub portions, the back wall and the tub body, remain integral and endure the remarkable mechanical stresses caused by the drum motion, especially during centrifugation. Nowadays the tubs are usually made of stainless steel and, since this material is relatively expensive, there has been a trend to reduce as much as possible the thickness of the tub, by means of several contrivances. An important obstacle to an appreciable reduction of the tub's thickness, is the junction between the back wall and the tub body, the edge whereof must have a remarkable resistance to the mechanical stresses. If in fact, the tub edge is made of an excessively thin sheet, the washing and centrifugation stresses bend and warp the sheet at the junction, causing the offset of the drum and water leaks, the back wall and the tub body not being securely integral. To overcome this problem, the back wall is sometimes fastened to the tub body by means of a cast iron cross member lying outside the back wall and fastened to the junction edge. This system, however, raises the production cost of the washing machine because of the greater number of assembling operations and of component parts, and furthermore raises the weight of the tub. The main aim of the present invention is to provide a reinforced tub for washing machines having such a fastening system of the tub body to the back wall to allow the use of thinner sheets for its construction, without jeopardizing the component parts resistance to the mechanical stress and the watertightness. Within this aim, an object of the invention is to provide a reinforced tub easily, and therefore economically, produced from an industrial point of view. A further object of the invention is to provide a reinforced tub having a long life and reliable fastening system between the tub body and the back wall, in terms of watertightness and mechanical resistance. The above aim, as well as these and other objects that will be more apparent later, are achieved by a reinforced tub, particularly for laundry washing machines, comprising a back wall associated with a tub body, said tub body having a substantially cylindrical shape and comprising a bottom edge, characterized in that the bottom edge comprises a further stiffening edge rigidly associated with said bottom edge. Further characteristics and advantages of the invention will be more apparent by the following description of a preferred embodiment, illustrated, by way of example in the enclosed drawings in which : Fig. 1 shows an isometric exploded view of a tub according to the invention; Fig. 2 is an enlarged cross section view of a detail of the junction between the tub body and the back wall; Fig. 3 is an isometric view of the tub body before its shaping; Fig. 4 is an isometric view of the tub body after its shaping; Figs. 5-7 are enlarged cross section views of the tub body edge. With reference to the cited figures, the tub, generally designated by the reference numeral 1 and adapted to contain a drum 14, comprises a tub body 2 and a back wall 3. The tub body generally has a cylindrical shape and is formed from a flat sheet 2a, illustrated in Fig. 3, bent and joined along the edges 2b, as illustrated in Fig. 4. The back wall 3 is fastened to the tub body bottom edge 4 which is conveniently bent to have a radial portion 5 adapted to cooperate with a similar radial portion 6 formed on the periphery of the back wall 3. As better shown in Fig. 2, a gasket 7 is first interposed between the bottom edge 4 of the tub body 2 and the portion 6 of the back wall 3, and subsequently a fastening ring 8 is applied to fasten the back wall to the tub body. According to the invention, the bottom edge 4 of the tub body is reinforced by means of a stiffening edge 9. Figs. 5-7 show some of the possible shapes of the stiffening edge which may extend either almost exclusively within the radial portion 5 (the edge 4a of Fig.5), or beyond the radial portion 5 covering part of the tub body (edges 4b and 4c of Figs. 6 and 7). The stiffening edge 9 is advantageously provided by bending the sheet 2a when it is still flat (Fig. 3), before the shaping operations, and optionally by welding it in order to ease the subsequent workings. The edge 9 can also be provided by simply welding a sheet metal to the radial portion 5, without bending the bottom edge 4 of the tub. It has been practically observed how the invention achieves the intended aim and objects, by providing a strong tub made of a thinner sheet metal and therefore with lower production costs. An advantage of the invention is also due to the easy shaping operations for manufacturing the tub, and particularly for forming the stiffening edge, that do not further complicate the production cycle. The reinforced tub according to the invention may have numerous modifications and variations, all within the inventive concept; furthermore, all the details may be substituted with technically equivalent elements. The materials employed, as well as the dimensions, may be any according to the specific needs and the state of the art. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: Reinforced tub, particularly for laundry washing machines, comprising a back wall (3) associated with a tub body (2), said tub body having a substantially cylindrical shape and comprising a bottom edge (4), said back wall (3) being associated with said tub body (2) at said bottom edge (4), characterized in that the bottom edge (4) comprises a further stiffening edge (9) rigidly associated with said bottom edge. Reinforced tub, according to claim 1, characterized in that said stiffening edge (9) is formed by bending said bottom edge (4). Reinforced tub, according to claim 2, characterized in that said stiffening edge (9) is subsequently welded to said bottom edge. Reinforced tub, according to claim 1, characterized in that said stiffening edge (9) is provided by welding a sheet metal to said bottom edge (4). Reinforced tub, according to one or more of the preceding claims, characterized in that said stiffening edge (9) is formed on said bottom edge (4) before the shaping of said tub body (2). Reinforced tub, according to one or more of the preceding claims, characterized in that said stiffening edge (9) is formed on said bottom edge (4) after the shaping of said tub body (2).

Inventors: MERLONI ANTONIO DR, MERLONI, ANTONIO, DR.
Applicants: MERLONI ANTONIO SPA, ANTONIO MERLONI S.P.A.
Application year: 1990
Main classification: D06F37
IPC codes: D06F37