Abstract:
In a method of producing an upholstered article, at least first and second cover portions of an upholstery cover are molded in mutually spatially separated relationship. The cover portions are fitted to a core portion to form the upholstery cover therearound. Defined between the outside surface of the core portion and the inside surface of the upholstery cover is a defined gap into which a coating material is introduced. The coating material on hardening joins the upholstery cover to the core portion.

Description:
FIELD OF THE INVENTION 
     The invention generally concerns a method of producing an upholstered article, that is to say for example an article which includes suitable padding for example for comfort-enhancing purposes, such as part of a motor vehicle seat, for example a seat armrest. 
     BACKGROUND OF THE INVENTION 
     Various methods are known for the production of upholstered articles. For example, DE 43 00 375 A1 discloses a method of producing an upholstered article comprising a first method step in which a cover for forming the outside component of the article is introduced in a taut and fold-free condition into a deep-drawing mold. Then, in a second step in the method, the cover is foam-backed with a reaction mixture which, after the reaction has taken place, forms a cushion core. A third step in the method then involves the provision of a body which is stable in respect of shape, at the rear side of the cushion core, being the side that is remote from the cover which accordingly forms the outside of the upholstered article. This operation can be effected by casting a hard coating material. Such a method can be carried into effect by employing a mold tool with first and second cover members which are different from each other. 
     A method of producing an upholstered article can also be effected by means of the use of a mold tool which comprises three different cover members. In such a method, in a first step therein, a skin or surface layer is cast, replacing the above-mentioned cover of the upholstered article. In a second step in this method, a cushion core is produced from a reaction mixture at the rear side or inwardly facing side of the cast skin, this involving the second cover member of the mold tool. In a subsequent third step in the method, a third cover member which replaces the second cover member is then used to produce a body which is stable in respect of shape at the rear side of the cushion core, by virtue of casting a suitable hard coating material. 
     Consideration may be given at this point to German patent application No 198 33 098 setting forth a method of producing an upholstered article, wherein an upholstery cover is produced by molding, with a hollow space or cavity which is open at one side being defined therein. A core portion is introduced into the cavity in the upholstery cover, the core portion being provided at its surface with raised configurations. The raised configurations of the core portion bear against the inside surface of the cavity of the upholstery cover so that the core portion is held at a defined spacing at all points from the inside surface of the upholstery cover. A coating material is then introduced into the gap determined between the inside surface of the cavity of the upholstery cover and the surface of the core portion, between the upholstery cover and the cushion portion. The coating material introduced into the gap fills the gap and is hardened in the gap, firmly connecting the core portion to the upholstery cover. That method is suitable in particular for the production of upholstered articles without undercut configurations because it would scarcely be possible, or it would be possible only at the cost of considerable complication and expenditure, to introduce a core portion having such undercut configurations into the upholstery cover which is open at one side and which would be correspondingly formed with undercut configurations. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a method of producing an upholstered article with core portion therein, wherein the core portion can readily have at least one undercut configuration and an upholstery cover around the core portion can nonetheless be easily produced and reliably joined to the core portion. 
     Another object of the present invention is to provide a method of producing an upholstered article which affords a simplified and rational operating procedure with the respective component parts of the upholstered article being produced in positions such as to facilitate manufacture of the article. 
     Yet another object of the present invention is to provide a method of producing an upholstered article which involves integration of the method steps involved in producing respective components of the article, such as to speed up the operating procedure of the method. 
     In accordance with the principles of the present invention, the foregoing and other objects are attained by a method of producing an upholstered article wherein at least two cover portions of an upholstery cover of the article are cast or molded in mutually spatially separated relationship. The cover portions are applied to a core portion, forming the upholstery cover therearound. A defined gap remains between the surface of the core portion and the inside surface of the upholstery cover, and a coating material is introduced for example by pouring into that gap. The coating material fills the gap and hardening thereof connects the core portion to the upholstery cover. 
     As will be seen from a detailed description of a preferred embodiment of the invention hereinafter, the fact that the upholstery cover is composed of at least first and second cover portions means that it is readily possible for the core portion to involve at least one or a plurality of undercut configurations. The cover portions of the upholstery cover then only have to be designed with suitable peripherally extending separation or end faces in order to be able to fit the cover portions to the core portion which has undercut configurations, in a condition of being suitably adapted to the core portion. 
     It will be noted that the cover portions of the upholstery cover and the core portion can be produced in mutually separate mold tools or in a common mold tool. 
     The coating material which is introduced into the defined gap between the core portion and the upholstery cover comprising suitable cover portions and which is hardened in the gap to join the core portion to the upholstery cover enclosing same is preferably a hard coating material. In that way the stability in respect of shape of the upholstered article produced in accordance with the method of the invention is achieved by virtue of the hard coating material in its hardened condition, when for example the core portion itself is not stable in respect of shape. It will be appreciated that it is also possible for the core portion itself also to be stable in respect of shape. In that case, the coating material which fills the gap between the core portion and the upholstery cover therearound, when in the hardened or set condition, can still further increase the level of stability in respect of shape of the article. 
     In a preferred feature of the invention, the coating material used is a polyurethane (PU)-hard coating material. Such a material is available at inexpensive cost. 
     A preferred feature of the invention provides that the cover portions of the upholstery cover are provided with connecting members at their end faces which extend at the periphery of the respective cover portions. In that arrangement the coating material penetrates between the end faces of the cover portions and mechanically firmly connects together the cover portions of the upholstery cover, after hardening has occurred, to form the upholstery cover. The connecting members may comprise openings and projections, pins or the like which can be fitted into the openings. That form of the method according to the invention, which involves the use of connecting members between the cover portions, affords the advantage that not only are the cover portions of the upholstery cover mechanically firmly connected to the core portion by means of the coating material, but also the cover portions become a virtually one-piece upholstery cover, along their peripherally extending end faces. That reliably prevents the occurrence of undesired points of separation between the end faces of the cover portions, without involving a complicated structure or operating procedure. 
     In accordance with another preferred feature of the invention the cover portions of the upholstery cover and/or the core portion can have raised parts for establishing the defined gap. As normally the core portion has a suitable level of stability in respect of shape, in comparison with the upholstery cover, it is desirable in particular for the core portion to be formed with raised parts defining the gap. 
     In a preferred feature of the invention the cover portions of the upholstery cover are cast or molded from a reaction foam material. It is advantageous to use a PU-integral foam material for that purpose. In combination with a PU-hard coating material between the cushion core portion and the upholstery cover, this use of a PU-integral foam material affords homogeneity in terms of the kinds of material used, and that can be an advantageous factor from the points of view of recycling and environmental protection. 
     In accordance with another preferred feature of the invention the core portion can be cast or molded from a reaction foam material. The core portion however may also comprise any other suitable material such as wood, polystyrene and the like. If the core portion is produced from a reaction foam material, it is preferable to use a PU-molding material in order also to ensure the above-mentioned homogeneity in terms of kinds of material used, in regard to the core portion of the upholstered article produced by the method in accordance with the invention. 
     Mechanical stability or stability in respect of shape of the upholstered article produced by the method of the invention can be still further enhanced by the core portion being formed with passage means extending therethrough. Those passage means are then filled by the coating material which fills and sets in the gap between the core portion and the upholstery cover. 
     Further objects, features and advantages of the present invention will be apparent from the following description of a preferred embodiment thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a mold tool for carrying out a method for producing an upholstered article having a core portion with an undercut configuration therein, 
     FIG. 2 is a sectional view of an upholstered article, the individual parts of which are produced by the mold tool shown in FIG. 1, with the sectional plane in FIG. 2 corresponding to that in FIG. 1, 
     FIG. 3 is a view in section taken along section line III—III in FIG. 2, 
     FIG. 4 is a view in section taken along line IV—IV in FIG. 3, and 
     FIG. 5 is a view on an enlarged scale of the detail indicated at V in FIG.  3 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     It will firstly be noted that the same features and components are indicated by the same respective references in each of FIGS. 1 through 5. 
     Referring therefore now firstly to FIG. 1, FIG. 1 is a sectional view showing a mold tool indicated generally at  10 , comprising a first central portion  12 , a second central portion  14 , a first cover portion  16  which is disposed on the side of the first central portion  12  remote from the second central portion  14 , and a second cover portion  18  disposed on the side of the second central portion  14  remote from the first central portion  12 . In the closed condition of the mold tool  10 , the first and second central portions  12  and  14  bear against each other in sealing relationship at faces on a first separation plane indicated at  20 . The first and second central portions  12  and  14  define between them a first mold cavity  22  for molding a core portion  24  of an upholstered article. An ingate  26  opens into the first mold cavity  22 . A reaction foam material is cast into the first mold cavity  22  through the ingate  26 , as indicated by the arrow  28 . The reaction foam material for constituting the core portion  24  produced in the first mold cavity  22  is preferably a PU-material which fills the first mold cavity  22  after reaction of the PU-material has taken place. 
     Reference numeral  30  in FIG. 1 denotes for example a bar or like member which extends through the first mold cavity  22 . Such a member  30  may be used when the upholstered article to be produced is for example a component such as a vehicle seat armrest. The first central portion  12  and/or the second central portion  14  are also provided with limbs or webs  32  which form through passages  36  in the core portion  24  comprising the reaction foam material  34 , after the mold tool  10  is opened. The core portion  24  is of a configuration involving a generally undercut portion as indicated at  38  in FIG.  1 . In that case for example as illustrated the first central portion  12  of the mold tool  10  is of a corresponding configuration at the surface thereof which defines the adjacent surface of the core portion  24 . The first and second central portions  12  and  14  are also provided in the region of the first mold cavity  22  with a plurality of recesses  40  disposed at spacings in the inwardly facing surfaces of the first and second central portions  12  and  14 . The recesses  40  serve to form on the molded core portion  24  raised parts which are also indicated at  42  in FIG. 1, formed from the reaction foam material  34  introduced into the mold cavity  22  for forming the core portion  24 . 
     In the closed condition of the mold tool  10 , the first central portion  12  and the first cover portion  16  define between them a mold cavity  44  for a first cover portion  46  of the upholstered article to be produced by the method according to the invention. Similarly, in the closed condition of the mold tool  10 , the second central portion  14  and the second cover portion  18  define between them a mold cavity  48  for a second cover portion  50 . The first central portion  12  and the first cover portion  16  bear sealingly against each other along a second separating plane  52 , when the mold tool  10  is in the closed condition. An ingate  54  opens into the mold cavity  44  for producing the first cover portion  46 . A reaction foam material  56  is introduced into the mold cavity  44  through the ingate  54  when the mold tool  10  is in the closed condition. The reaction foam material  56  is preferably a PU-integral foam material. The introduction of such material into the mold cavity  44  through the ingate  54  is indicated by the diagrammatic arrow  58 . 
     In the closed condition of the mold tool  10  the second central portion  14  and the second cover portion  18  bear sealingly against each other along a common third separating plane  60  in order to define between them the mold cavity  48  for the second cover portion  50 . An ingate  62  opens into the mold cavity  48  for the introduction into the mold cavity  48  of a reaction foam material  64 , as diagrammatically indicated by an arrow  66 . This last-mentioned reaction foam material  64  is preferably a PU-reaction foam material like the reaction foam material  56  for the first cover portion  46 . 
     After the core portion  24  and the two cover portions  46  and  50  have been produced by molding in their respective mold cavities, the mold tool  10  is opened along the separating planes  20 ,  52  and  60  by virtue of suitable relative movement of the mold portions  12 ,  14 ,  16  and  18 . This is indicated diagrammatically by the double-headed arrows  68  in FIG.  1 . After the mold tool  10  has been opened, the core portion  24  and the cover portions  46  and  50  can be appropriately removed. 
     Thereupon, the cover portions  46  and  50  are fitted around the core portion  24 . In that case, the cover portions  46  and  50  enclose the core portion  24  on all sides to constitute an upholstery cover which is generally indicated at  70  in FIG.  2 . The way in which the cover portions  46  and  50  enclose the core portion  24  to constitute an upholstery cover around same can be clearly seen from FIGS. 2,  3  and  4  showing the upholstered article in the assembled condition. 
     When the cover portions  46  and  50  are in their positions of being fitted to the cover portion  24 , the raised parts  42  which project from the outside surface of the core portion  24  define a gap which is indicated at  72  in FIGS. 2 through 4, between the core portion  24  and the cover portions  46  and  50 . A coating material indicated generally at  74  is then introduced into the gap  72 , for example by being poured or cast therein. The coating material which is preferably a hard coating material such as a PU-hard coating material completely fills up the gap  72  and connects the core portion  24  to the upholstery cover  70  formed by the cover portions  46  and  50 , when the coating material  74  hardens in the gap  72 . 
     Reference will now be made to FIG. 5 showing that the first cover portion  46 , at its peripherally extending end face  76 , is formed with openings  78  of which only one is visible in FIG.  5 . In a corresponding manner, the peripherally extending end face  80  of the second cover portion  50  is formed with projections or pin portions  82  which are matched in terms of shape to the openings  78 . The openings  78  and the projections  82  thus constitute connecting means for joining the cover portions  46  and  50  together. The coating material  74  can penetrate between the adjacent end faces of the cover portions  46  and  50  and mechanically firmly connect them together after the coating material  74  has set and hardened. 
     For that purpose, on the side that is towards the gap  72 , the peripherally extending end face  76  and the peripherally extending end face  80  of the first and second cover portions  46  and  50  respectively are spaced from each other in such a way that a peripherally extending gap  84  is formed between them. The gap  84  is in communication with the gap  72  between the core portion  74  and the upholstery cover  70  formed from the cover portions  46  and  50 . Consequently, like the gap  72  between the core portion  24  and the upholstery cover  70 , the above-mentioned gap  84  is filled with the coating material  74  so that, in the hardened condition, the cover portions  46  and  50  are firmly connected together along the end faces  76  and  80  to constitute the upholstery cover  70  enclosing the core portion  74 . It will be seen that reference  86  in FIG. 5 denotes the connecting configuration afforded by the co-operation of the openings  78  and the projections  82  for connecting the cover portions  46  and  50  together. 
     It will be appreciated that the above-described embodiment of the method according to the invention has been set forth solely by way of example and illustration of the principles of the invention and that various other modifications and alterations may be made therein without thereby departing from the spirit and scope of the invention.