Patent Publication Number: US-2005132556-A1

Title: Washing machine drum

Description:
OBJECT OF THE INVENTION  
      The invention relates to a washing machine drum formed by a cylindrical wall, which contains several openings, and connected by means of a lock seam to two sheet metal layers.  
      1. General Prior Art  
      It is known that washing machine drums are formed by a side wall, fitted with several openings and connected at its ends to two sheet metal layers by means of a lock seam defining a peripheral projection, which is formed around the cylindrical side wall by a first folding of 180° of a section of the wall of the first sheet metal layer around the cylindrical wall and by a second folding of 180° of the double wall, which is formed after the first folding by the sheet metal layer and the cylindrical wall.  
      2. Description of the Invention  
      The tumbling speed of washing machines gets higher and higher, causing the drum to have to withstand greater loads, which can cause tearing in the seam join of the cylindrical lateral surface with the sheet metal layers.  
      Furthermore bulging of the cylindrical side wall is caused during high-speed tumbling, which in turn causes the loads, which the seams have to endure, to be greater, enabling tearing of the drum in the seam regions.  
      The object of the invention is to provide reinforcing for the lock seam, which forms the connection between the sheet metal layers and the cylindrical side wall, so that these connections endure greater loads as such caused by tumbling at high speeds.  
      The object of the invention is also to reinforce the cylindrical side wall to provided the latter with greater resistance and with mechanisms, which protect the seam join to enable withstanding greater loads as such which are caused by tumbling at high speeds.  
      To eliminate the abovementioned drawbacks the invention shows a washing machine drum, which is designed similarly to conventional washing machine drums by a cylindrical side wall, fitted with several openings, and is connected by means of a peripheral lock seam at its ends to a front sheet metal layer and a rear sheet metal layer, and it is characterised in that along the lock seam there is stamping, which acts on all walls of the sheet metal layers, forming the lock seam, such that this construction creates greater resistance of the lock seam to loads which are caused by the effect of centrifugal force on the cylindrical wall, so that the possibility of tearing and/or bending of the lock seam is decreased whenever the drum rotates at high speeds.  
      The stamping is arranged according to the length on each of the walls forming the lock seam.  
      In one embodiment of the invention the stamping is arranged obliquely to the lock seam, that is, the different stampings, on each of the different walls, forming the lock seam, are aligned in a transverse direction.  
      The drum of the invention also has as an additional feature the fact that the cylindrical wall is fitted with several small depressions, so that the surface of the cylindrical wall is enlarged, so that it provides larger resistance, making it difficult for the cylindrical wall to bulge out at high speeds. But in case such bulging does occur, it acts on the depressions and not on the lock seam, so that the seam joins have to undergo a lesser load and as a result tearing in the seam region is made more difficult.  
      In an embodiment of the invention each depression contains one of the flood holes of the drum, but these flood holes can be located according to any preferred configuration outside the depressions or can alternate in same.  
      It should also be pointed out that according to an embodiment of the invention the depressions have a truncated section, but they can also present any other kind of section. 
    
    
      For a better understanding of the description and as a part of same several figures are attached, in which the object of the invention is illustrated clearly and not limited, in which:  
       FIG. 1  is a schematic perspective view of a washing machine drum,  
       FIG. 2  is a partial view of a body of a conventional drum along the section line in  FIG. 1  and  
       FIG. 3  is a view along the same section line on a drum body of the invention.  
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
      A description of the invention on the basis of the abovementioned figures follows.  
      The drum according to the present invention is formed as in conventional drums by a cylindrical wall  3 , which is connected by means of a lock seam  5  to a rear mounting  1  and a front mounting  2 .  
      The surface of the cylindrical wall  3  is additionally provided with several openings  4  for the water supply and drainage.  
       FIG. 2  is a partial section of the abovedescribed elements according to the prior art, showing that the lock seam  5  is created by a first folding of 180° of a section of the wall of the sheet metal layer  1  or  2  on the cylindrical wall  3 , so that a second folding likewise of 180° of the double wall, formed after the first folding, takes place on the cylindrical wall  3 .  
      The disadvantage of this design, as described in the preceding paragraphs, is that tearing of the washing machine drum at the seam join  5  can be caused when the drum rotates at high speeds. At the same time a noticeable bulging of the cylindrical wall  3  occurs, whereby the seam ends  5  are subjected to a greater load, which again reinforces the risk of tearing the seam join.  
      To eliminate these disadvantages the invention contains the novel features, that stamping is effected on the lock seam  5  for example by pressing two raised pins along the entire lock seam. The stamping is formed on all sheet metal layers of the walls inside the seam join, by means of which the sheet metal layers are joined to one another positively.  
      This stamping increases the strain which the drum can withstand when it is driven at high tumbling speeds, so that the probability of a tear in the seam join of the drum occurring can be considerably reduced.  
      To further prevent bulging of the cylindrical wall  3  depressions  7  with truncated section are made in the cylindrical wall  3 , the floor of which contains flood holes  4  for the water supply/drainage to carry out the washing procedure.  
      This design of the depressions is caused by a larger surface and resistance of the drum. When the cylindrical surface  3  bulges at high tumbling speeds however, the depressions  7  offer protection from tearing or pleating of the seam ends  5 .  
      Greater resistance to the load of the side wall and in the region of the seam is therefore achieved by the drum equipped according to the present invention, and at the same time the latter are protected in case bulging of the mantle surface  3  might occur.