Patent Publication Number: US-2016236812-A1

Title: Blow-Molded Case and Strengthened Structure Thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Hong Kong Patent Application No. HK15101717.3 filed on Feb. 16, 2015, the content of which is hereby incorporated by reference. 
     FIELD OF INVENTION 
     The present invention relates to a blow-molded product, in particular to a blow-molded case and the strengthened structure thereof. 
     BACKGROUND OF INVENTION 
     In recent years, blow-molded cases are gradually replacing foam boxes and cardboard boxes in some areas of people&#39;s daily life. Generally, the blow-molded cases in the market adopt blow molding process of plastic preform. The plastic preform is made by the process which includes injection molding or extruding process. The blow-molded case made by the aforesaid process has unavoidable defects, and that is there is a clearance between the inner wall and the outer wall of the corner of the blow-molded case in order to allow the blow-molded airflow to pass through. In addition, the inner wall and the outer wall are mostly arranged in a parallel structure. This parallel structure will lead to undesired strength of the blow-molded case. When the corner of the blow-molded case collides with other objects, the blow-molded case will collapse or even break easily. The article within the blow-molded case will then be exposed. If food is stored in the blow-molded case, the situation becomes more embarrassing. Thus, a blow-molded case with corners of higher strength and the strengthened structure thereof is desired. 
     SUMMARY OF INVENTION 
     The present invention is to provide a strengthened structure for a blow-molded case which comprises a housing. The housing includes an inner shell and an outer shell. The inner shell and the outer shell are connected at a first position by a connecting piece so that a cavity is formed between the inner shell and the outer shell. The inner shell and the outer shell are pressed together at least partially at the corners of the housing so that the connecting piece, the inner shell and the outer shell enclose to form a closed support structure. 
     In a preferred embodiment, the cross section of the closed support structure is a closed trilateral support structure. A first side of the trilateral support structure is formed by a portion of the connecting piece lying between the outer shell and the-inner shell. A second side of the trilateral support structure is formed by a portion of the outer shell lying between the connecting piece and the corner. A third side of the trilateral support structure is formed by a portion of the inner shell lying between the connecting piece and the corner. 
     In another preferred embodiment, the outer shell and the inner shell form a smooth rounded corner at the corner. 
     In another preferred embodiment, the outer shell and the inner shell form a chamfer at the corner. 
     In a further preferred embodiment, the inner shell has a first convex part protruding toward the outer shell. The first convex part is pressed close to the outer shell. 
     In yet another preferred embodiment, the outer shell has a second convex part protruding toward the inner shell. The second convex part is pressed close to the inner shell. 
     In another preferred embodiment, the inner shell gradually gets close to the outer shell at a location near the corner in a direction toward said corner until the inner shell and the outer shell are pressed together. 
     In another aspect, the present invention provides a blow-molded case having a strengthened structure as described above. 
     In a preferred embodiment, the corner is located at a junction of the side wall and an adjacent side wall of the blow-molded case. 
     In another preferred embodiment, the corner is located at the junction of the side wall and the bottom of the blow-molded case. 
     The implementation of the present invention can realize a blow-molded case of higher strength and higher resistance to impact. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a structural diagram of the strengthened structure for a blow-molded case of the first embodiment of the present invention. 
         FIG. 2  is a structural diagram of the strengthened structure for a blow-molded case of the second embodiment of the present invention. 
         FIG. 3  is a cross section diagram of the blow-molded case in one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Refer to  FIG. 1 , the present invention provides a strengthened structure for a blow-molded case. The strengthened structure comprises a housing  100 , which has an inner shell  110  and an outer shell  130 . The inner shell  110  and the outer shell  130  are connected at a first position by a connecting piece  150  so that a cavity is formed between the inner shell  110  and the outer shell  130 . The inner shell  110  and the outer shell  130  are pressed together at least partially at a corner  200  of the housing  100 . Thus, the connecting piece  150 , the inner shell  110  and the outer shell  130  enclose to form a closed support structure. The cross section of the closed support structure is a closed trilateral support structure. A first side of the trilateral support structure is formed by a portion of the connecting piece  150  lying between the outer shell  130  and the inner shell  110 . A second side of the trilateral support structure is formed by a portion of the outer shell  130  lying between the connecting piece  150  and the corner  200 . A third side of the trilateral support structure is formed by a portion of the inner shell  110  lying between the connecting piece  150  and the corner  200 . The inner shell  110  and the outer shell  130  are pressed together at least partially at the corner  200  of the housing  100 , and thus the strength of the corner  200  is increased so that the corner  200  of the blow-molded case is less likely to be damaged and the integrity of the whole case is protected. As the trilateral support structure is more stable than the quadrilateral support structure, the connection structure of the inner shell  110 , the outer shell  130  and the connecting piece  150  will not deform easily. 
     In the process of manufacturing, it should be avoided to make the corner  200  as a right-angle form which is easily to be dented. Thus the inner shell  110  and the outer shell  130  at the corner  200  shall adopt a smooth rounded corner. 
     When pressing the inner shell  110  and the outer shell  130  together, the inner shell  110  gradually gets close to the outer shell  130  at a location near the corner  200  in a direction toward the corner  200  until the inner shell  110  and the outer shell  130  are pressed together. 
     Refer to  FIG. 2 , the difference between the second embodiment and the first embodiment shown in  FIG. 1  is that the inner shell  110  and the outer shell  130  at the corner  200  adopt an impact-resistant chamfer. 
     In order to further increase the structure strength of the housing  100 , the inner shell  110  can be set with a first convex part (not shown in figures) protruding toward the outer shell  130 . As the outer end of the first convex part is closer to the outer shell  130 , it is less likely to be damaged when colliding with hard objects. Similarly, the outer shell  130  can be set with a second convex part (not shown in figures) protruding toward the inner shell  110 . The second convex part of the outer shell  130  is pressed close to the inner shell  110 . 
     Refer to  FIG. 3 , the present invention also provides a blow-molded case comprising a bottom  310  and side walls  320  extending upward from the edges of the bottom  310 . The side walls  320  enclose and constitute a half closed body with the bottom  310 . The ends of the side walls  320  far away from the bottom  310  form an opening of blow-molded case. In this embodiment, the blow-molded case has a double-shell structure and has a strengthened structure at the corner as shown in  FIG. 1 . The corner is located at the junction of the side wall and the adjacent side wall and/or at the junction of the side wall and the bottom of the blow-molded case. The inner shell  110  has a convex part  170  protruding toward the outer shell  130  at the side wall  320 . The outer end of the convex part  170  is pressed close to the outer shell  130 , resulting in enhancement of the strength of the side wall. 
     In other embodiments, the corner of a case lid (not shown in the figures) can also be set with the strengthened structure as shown in  FIG. 1 . 
     In traditional blow-molded solution, the circulation of airflow within the blow-molded case has to be ensured, the blow molding will be affected by using a pressing scheme. The blow-molded case provided by the present invention first adopts blow molding and then the method of supplementary case-hardening. After air passes through to form a hollow structure, corresponding dies are used to carry out the pressing scheme. By pressing the inner shell  110  and the outer shell  130  together at the corner  200 , the present invention is realized. 
     Under the premise of not departing from the concept of the present invention, those of ordinary skill in the art will understand that several modifications and improvements can be made, but the modifications and improvements will fall into the scope of the present invention. Therefore, the scope of protection of the present invention is defined by the claims.