Abstract:
The present invention is related to a drum ( 1 ), used in washing machines, preferably laundry machines, into which laundry to be washed is to be placed, capable of performing washing by rotational movement around its central axis, preferably made of plastic, comprising a main body ( 2 ) and a rear cover ( 3 ), whereby said rear cover ( 3 ) comprises a circular edge ( 10 ) which surrounds the main body ( 2 ) and the main body ( 2 ) comprises an edge socket ( 14 ) in which the rear cover edge is located, the main body ( 2 ) and the rear cover ( 3 ) being connected to each other without forming any protrusion on the outer face of the drum ( 1 ).

Description:
BACKGROUND OF THE INVENTION 
   The present invention is related to a drum of plastic material used in washing or drying machines, preferably front-loading washing machines, capable of performing washing operation by rotating. 
   In the state of the art washing machines, preferably laundry machines comprise a fixed tub and a drum rotating inside such a tub. As an outcome of unbalanced distribution of laundry inside the revolving drum, during the washing, the centre of gravity of objects spinning around drum axis in laundry machines goes away from rotational axis. Thus, centrifugal forces affect all the components of washing machines, particularly the fixed tub and the revolving drum. It is preferred to produce revolving drums from metal plates instead of plastic materials with respect to strength against excessive load and methods of manufacturing. 
   U.S. Pat. No. 5,167,898 describes a mold group enabling production of a single piece plastic drum comprising perforations with openings in the form of teardrops. 
   In the EP 0595040, a tub is described having perforations formed by cutting from projections outside which are inside towards extending from outside in order to prevent harming of the laundries inside the tub by the flash. 
   In EP0854223, a fastening method by riveting for a plastic tub is described. 
   In the EP 0789104 a system of fastening for holding a plastic tub made of two pieces by using claws, is described. 
   SUMMARY 
   The object of this invention is to achieve a plastic drum rotating around its central axis for household appliances, preferably for laundry machines. 

   
     DRAWINGS 
     Drum embodied to attain the objects of this invention has been shown in figures attached, where 
       FIG. 1  is a three-dimensional front view of a washing/drying machine. 
       FIG. 2  is a schematic view of a washing/drying machine comprising a drum and a tub. 
       FIG. 3   a  is a three-dimensional front view of a drum, 
       FIG. 3   b  is a three-dimensional rear view of a drum. 
       FIG. 4   a  is an exploded rear three-dimensional view of a drum. 
       FIG. 4   b  is an exploded three-dimensional front view of a drum. 
       FIG. 5   a  is a three-dimensional rear view of back cover. 
       FIG. 5   b  is a three-dimensional front view of back cover 
       FIG. 6   a  is a perspective rear view of a drum cut into half 
       FIG. 6   b  is a perspective front view of a drum cut into half 
       FIG. 7   a  is a perspective view taken before rivets, which ensure joining main body and rear part together, are crushed. 
       FIG. 7   b  is a perspective view taken after rivets, which ensure joining main body and rear part together, are crushed. 
   

   DESCRIPTION 
   The parts are numbered as follows:
           1 —Drum     2 —Main body     3 —Rear cover     4 —Rib     5 —Attachable plate     6 —Discharge duct     7 —Torque conveyor     9 —Body hole (orifice)     10 —Edge     11 —Rib gap     12 —Rivet projection     13 —Edge coupling extension     14 —Edge socket     15 —Drum claw     16 —Drum claw recess     17 —Edge socket coupling projection     18 —Edge socket coupling recess     19 —Front surface     21 —Resting duct     22 —Washing/drying machine     23 —Tub     26 —Angular cover support     27 —Circular cover support     28 —Cover slot     29 —Support ring     30 —Curved cover support     31 —Rivet socket     32 —Rivet head     37 —Duct discharge hole     38 —Drum discharge hole     39 —Edge coupling recess     40 —Trace hiding socket       

   Washing/drying machines, preferably in front loading washing machines, a motor is provided to activate the machine, a fixed tub ( 23 ) into which the washing fluid is filled and discharged, a drum ( 1 ) made of a non-filler polymeric material such as a thermoplastic material or a material with filler such as fiber, calcium carbonate into which laundries to be washed are placed, rotating by the motor around its central axis. Drum ( 1 ) comprises a main body ( 2 ) and a rear cover ( 3 ). 
   Rear cover ( 3 ) comprises a circular edge ( 10 ) surrounding the main body ( 2 ). Edge ( 10 ) comprises more than one edge coupling extension ( 13 ) and more than one edge coupling recesses ( 39 ) ensuring rear cover ( 3 ) to facilitate the rotation of the main body ( 2 ). 
   The main body ( 2 ) comprises an edge socket ( 14 ) into which an edge ( 10 ) is located on its outer surface. Edge socket ( 14 ) comprises an edge socket coupling recess ( 18 ) fitting into the edge coupling projection ( 13 ) and an edge socket coupling projection ( 17 ) fitting into the edge coupling recess ( 39 ). On the edge socket ( 14 ), a discharge duct ( 6 ) is provided to facilitate discharge of washing fluids. On the discharge duct ( 6 ), one or more discharge holes ( 37 ) opening into the inner wall of the main body ( 2 ) are provided. On rear cover ( 3 ), at a location where the edge ( 10 ) meets back cover (also called a “rear cover” herein) ( 3 ), there is a resting duct ( 21 ) on which the edge socket ( 14 ) projection rests. Inside the resting duct ( 21 ), there are one or more drum discharge holes ( 38 ) ensuring discharge of washing fluid accumulated on the connecting edge between rear cover ( 3 ) and main body ( 2 ). 
   The rear cover ( 3 ) comprises a torque conveyor ( 7 ) made of a material different from that of the drum, transferring the power from the motor to the drum to rotate the drum ( 1 ). Torque conveyor ( 7 ) is preferably made of aluminum material to reduce weight and to increase strength. 
   On the rear cover ( 3 ), there are one or more angular cover supports ( 26 ) and one or more circular cover supports ( 27 ) located as intersecting each other around torque conveyor ( 7 ) to enhance rear cover ( 3 ) resistance against forces formed on rear cover as a result of centrifugal forces. At parts where angular cover supports ( 26 ) and angular cover supports ( 27 ) are not correspond and where it is required to provide some further strength, cover curving supports ( 30 ) are placed in these parts in required number and corresponding forms. 
   On angular cover supports ( 26 ) and on circular cover supports ( 27 ), preferably at crossings, there are more than one reinforcing support rings ( 29 ) in curved form. One or more cover perforations ( 28 ) preferably in circular form to facilitate the transmission of fluids and gases in drum ( 1 ) during the washing or drying cycle are provided between angular cover supports ( 26 ) and circular cover supports ( 27 ). 
   On the inner wall of the rear cover ( 3 ), one or more drum claws ( 15 ) are provided for the mounting preferable in various directions onto the main body ( 2 ). 
   In front of the main body ( 2 ), there is a front surface preferably in the form of a ring ( 19 ), whereas on the inner surface thereof, one or more body holes ( 9 ) to transfer fluids which the body contains, one or more trace concealing sockets ( 40 ) hiding the flash, which might have formed due to mold extraction from the inner surface during its production and one or more ribs ( 4 ) produced as single-piece with the main body, to activate laundry to be dried or washed by rotational movement of drum ( 1 ) so as to increase drying or washing efficiency. Rib ( 4 ) comprise a rib gap ( 11 ) and a drum claw ( 16 ) fixing to the main body and rear cover ( 3 ) by claw locking the drum claw ( 15 ) into the rib gap ( 11 ). 
   On the main body ( 2 ), there is one or more rivet projections ( 12 ) preferably of rectangular shape, and rivet recesses ( 31 ) in corresponding number and shape of rivet projections ( 12 ) so as to hold them on the rear cover ( 3 ). 
   The drum ( 1 ) contains one or more attachable plates ( 5 ) that have one or more rib holes to transmit fluids and gases, and can be mounted whenever desired by the manufacturer, but cannot be moved away by user without seeking help from the manufacturer. 
   In another embodiment of the invention, attachable plate ( 5 ) is not utilized and body holes ( 9 ) are not drilled at parts where attachable rib ( 5 ) exists. 
   While the drum is manufactured, the torque conveyor ( 7 ), which is manufactured beforehand, is positioned into the mold preferably with the aid of a mold centering projection. Plastics are injected into the mold to ensure that a part of the torque conveyor ( 7 ) is retained inside the rear cover material. At the same time, cover slots ( 28 ) are opened from the rear cover ( 3 ) inner wall towards the rear cover ( 3 ) outer wall by the help of inserts, preferably with countersink. In this way, formation of flash, inside the drum ( 1 ), particularly on and over the cover slots ( 28 ), causing damage to laundries are eliminated. Mold is opened to extract in single-piece rear cover ( 3 ) embodying torque conveyor ( 7 ). The main body ( 2 ), in turn, is manufactured with plastic injection as a single piece with ribs ( 4 ). In order to prevent the formation of flash, which harms laundry to be dried and washed, body holes ( 9 ) at parts where ribs ( 4 ) do not exist are drilled countersunk by means of cores from the drum inner wall towards its outer wall. Hiding the flash, which insert edges may leave behind on inner wall of the main body ( 2 ) is provided by using trace-concealing socket ( 40 ). For inserts to operate in the closed inner volume of the main body and for removing the main body ( 2 ) from the mold, it is not possible to drill perforations at some parts of the main body ( 2 ). If it is desired to drill perforations at such sites, using outer inserts, body perforations from outside to inwards are drilled. However, body perforations drilled there may cause flash at the inner side of the main body which harms laundry that will be washed or dried. In order to prevent such flash to harm laundries, attachable plates ( 5 ) having rib holes with countersink, manufactured as hollow and separately from the main body ( 3 ) in order eliminate imbalance of load distribution and not to prevent circulation of washing the fluid, are used over these harmful holes including flash. In this way, conveyance of flux such as gases and fluids existing there is also provided. 
   After attachable plates ( 5 ), rear cover ( 3 ) and the main body ( 2 ) are manufactured, and after attachable plates ( 5 ) are mounted on to the main body ( 3 ), drum claws ( 15 ) are fixed by pushing into drum claw recess ( 16 ) and in the meantime, the edge ( 10 ) seats on edge socket ( 14 ) such that edge coupling extension ( 13 ) fits into the edge piece coupling recess ( 18 ), and the edge coupling recess ( 39 ) fits into the edge coupling projection and rivet projections ( 12 ) on the main body ( 2 ) are located inside the rivet cap ( 31 ) on the rear cover ( 3 ). After the drum claws ( 15 ) are placed inside the drum claw recess ( 16 ), rivet projections ( 12 ) on the main body ( 2 ) are heated and pressed thereto, rivet heads ( 32 ) in number as much as number of rivet projections ( 12 ) and of width sufficient to prevent them to release from their housings are formed. So, on the rear cover ( 3 ), fixing is provided on several points and the main body ( 2 ) is fixed, without using any additional piece, with attachable plates and the rear cover ( 3 ). 
   Particularly, for drums ( 1 ) working under heavy torque conditions, and/or at high speed edge ( 10 ) and edge socket ( 14 ) are welded to each other using plastic fastening methods such as friction weld, hot point welding, laser welding to fix them. 
   In another embodiment of the invention, the edge ( 10 ) and edge socket ( 14 ) are fixed to each other using fastening means such as rivets or screws. 
   By means of connecting edge ( 10 ) to edge socket ( 14 ), the main body ( 2 ) and the rear cover ( 3 ) are fixed to each other and the drum ( 1 ) is formed without any projection being apparent on its outer face. In this way, the drum ( 1 ) rotates inside the tub ( 23 ) in any direction around its axis, without causing any harm to tub. 
   As the drum ( 1 ) is made of polymeric materials, pieces, which form the drum ( 1 ) may be produced in the same, different or in transparent colors.