Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-12-08
2003-09-23
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S245000, C156S290000, C156S308400, C264S511000, C264S571000, C264S222000, C264S266000
Reexamination Certificate
active
06623588
ABSTRACT:
A method of manufacturing a foil-wrapped breast prosthesis and a shaping tool for use in performing the method.
The invention relates to a method of manufacturing a foil-wrapped breast prosthesis with a filling consisting of a curable compound, preferably a silicone compound, by which
at least two foil sheets of a formable plastic material are joined for producing a prosthesis bag, leaving at the joint a filling opening,
through which the bag is filled with a quantity of said compound and the filling opening is sealed after air bubbles have been expelled,
the filled prosthesis bag is placed in a mould having a first mould part with an open mould cavity corresponding to the desired shape of the front of the prosthesis, the bag being positioned with respect to the mould cavity and secured to the mould,
whereafter the Filling is cured and the moulded prosthesis is removed from the mould.
The invention also relates to a shaping tool for use in performing the method.
From DE-C2-33 36 279 and U.S. Pat. No. 4,249,975 methods of manufacturing breast prostheses are known by which injection of the silicone compound used as filling is performed under pressure during the actual curing process, which is performed in a closed mould. In this connection, it is known from said DE publication to bring the walls of the prosthesis bag into contact with the walls of the mould cavity by applying vacuum before injecting the silicone compound.
To avoid the disadvantages by injecting the silicone compound under pressure during the actual curing process, a manufacturing method of the above mentioned kind is suggested in GB-A-2 257 387, by which the prosthesis bag is filled before being placed in the curing mould, which also in this case is closed, the actual mounting taking place under application of vacuum.
In a method of the above mentioned kind, the manufacturing can be performed in practice e.g. by welding together two sheets of polyurethane foil, which have been pre-shaped for forming the front and the rear side, respectively, of the prosthesis, into a prosthesis bag by means of a contour welding tool, thereby leaving a gate for use in filling the curable Prosthesis mass, which usually consists of a vulcanizable silicone compound. By the filling, a predetermined volume of the filling compound is admitted to the prosthesis bag by means of conventional mixing and dosing equipment, whereafter the gate is sealed by high-frequency or hot welding, possibly after having expelled air bubbles.
However, for the method according to the above mentioned GS patent application, an over-charging of the prosthesis bag is required to obtain a fully moulded front with an intended anatomic shape with a nipple, which generally results in an unintentional thickening of the prosthesis edge, the prosthesis thus not fitting tightly to the body.
The purpose of the invention is to provide a method by which the above mentioned problem can be avoided, and a shaping tool which to a considerable extent eases the handling of a prosthesis bag by placing and fixing it in a mould or a curing shell.
In this respect, according to the invention a method of the above mentioned kind is characterized in that the curing is performed without closing the mould cavity and while maintaining vacuum therein, at least in the beginning of the curing.
As the front of the prosthesis bag is kept in close contact with the wall of the mould cavity until the filling, or at least the part of it which is close to the wall, has cured, a considerably improved certainty is obtained for a fully moulded front with the desired shape corresponding to the mould cavity in the generally replaceable first mould part and with thin edge parts, making the prosthesis fit well to the body.
At the same time, greater freedom in the elaboration of the rear side of the prosthesis is obtained, as an expansion of the prosthesis mass, as a result of thermal expansion during the curing, can be routed to the areas of the rear side which are less important to the appearance and function of the prosthesis.
As such method according to the invention can be performed without using a rear block, although such a rear block is applied in most cases to obtain a desired shaping of parts of the rear side of the prosthesis. The shaping of the rear side can also be utilized for adjusting the flexibility and elasticity of the prosthesis and, in case of large prostheses, possibly for adjusting the weight of the Prosthesis.
The maintaining of vacuum during the curing must be of such duration that at least the part of the filling which is close to the front wall of the prosthesis has cured sufficiently. The duration of this period will depend and partly on the size of the prosthesis, partly on the curing temperature. For practical reasons, it will often be preferable to maintain vacuum during the whole curing process.
The application of vacuum, at least in the beginning of the curing process, makes it unnecessary to dose the bag accurately to obtain well-defined front and rear sides, as the front is retained while at the same time the critical parts of the rear side can be shaped as desired. Thereby interalia sub-filling of the bag, due to a too small dosing or unfavourable thermal/curing conditions, can be shifted to less critical areas of the rear side.
In this way, better control of the quality of the finished product is obtained.
In addition, the rear side of the prosthesis can be elaborated with thin edges for obtaining form-fit contact with the body.
As by the method according to the invention shaping is preferably performed of the foil wall intended to form the rear side of the prosthesis, by bringing a rear block into contact with the prosthesis bag placed in the mould cavity without closing the cavity, such a rear block can, for manufacturing self-supported breast orostheses, be utilized with advantage for placing stitching elements, which are subsequently transferred to the prosthesis bag by welding during the curing.
The shaping tool according to the invention provided for use in performing the method is of the type which comprises a first mould part having an open mould cavity corresponding to the desired shape of the front of a breast prosthesis, means for providing vacuum in said mould cavity, and means for tightening the parts of the joined foil sheets in a prosthesis bag which are placed outside the joint placed at the opening edge of the mould cavity.
For obtaining simple handling of a prosthesis bag in connection with mounting and fixing, the shaping tool is characterized in that said tightening means comprise a tightening frame connected with the first mould part, which frame has a packing for abutment with the parts of the foil sheets which are situated outside the opening edge of the first mould part at the placing of the prosthesis bag in the first mould part, and that at least one rear block is connected with the tightening frame in such a way as to allow said shaping of the rear wall of a prosthesis bag placed in the first mould part to be performed without closing the mould cavity in a preferred embodiment, the packing is designed in such a way that, after closing the frame with respect to the first mould part, it permits tightening of said foil sheets by stretching in only one direction in the packing plane away from the mould cavity, but prevents movement of the foil sheets in the other direction, whereby the joint is made to be flush with the opening edge of the mould cavity. Hereby the otherwise rather complicated tightening process is facilitated and accurate positioning of the prosthesis bag in the mould cavity is secured.
REFERENCES:
patent: 5035758 (1991-07-01), Degler et al.
patent: 2604744 (1977-11-01), None
patent: 2564728 (1985-11-01), None
patent: 2257387 (1993-01-01), None
Ball Michael W.
Coloplast A/S
Haran John T.
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