Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Patent
1983-04-19
1986-07-08
Simmons, David
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
29413, 83862, 83880, 83881, 156510, B32B 3100
Patent
active
045991260
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method for severing laminates of a plastic material and a metal. More particularly the invention relates to a method for severing such laminates in a way which reduces the likelihood of delamination taking place between the plastic material and the metal during or after the severing of the laminate.
It is known to form laminates of a synthetic plastic material, such as polyolefins and polyamides, and a metal such as tinplate. It has been proposed to use such laminates in the formation of containers and like goods. It has been found that conventional metal shearing and punching techniques are not satisfactory for severing such laminates when they are to be formed up into finished articles. Conventional shearing techniques have been found to predispose the severed laminate to delamination. This predisposition to delamination is particularly noticeable where an edge portion of the severed laminate is to be deformed such as by being rolled up into a seam or by being drawn into a formed shape. The delamination may be exhibited by the complete or partial separation of the plastic layer from the metal layer or by the formation of wrinkles or puckering in the plastic layer, particularly at the edges of the laminate.
It has been proposed in U.S. Pat. Nos. 3,604,295 and 3,656,379 to sever laminates of the type to which the present invention relates by firstly cutting a groove in the plastic layer up to its interface with the metal layer and then, in a separate operation, cutting through the metal layer.
The present inventions have found that the potential for delamination may be substantially reduced by forming an indentation in the laminate which extends through the plastic layer and into the metal layer. This indentation being caused by means which cause the plastic material along the line of the indentation to be displaced substantially laterally. This invention differs from the prior art described above both in that the indentation is formed by displacement of the plastic material rather than by cutting it out and in that the indentation extends through the plastic layer into the metal layer. It is believed that these two features contribute significantly to the efficacy of the process according to this invention.
The present invention consists in a method of severing a laminate of the type including a layer of a metal and a layer of a flexible synthetic plastic material, the method comprising forming an indentation of substantially channel-shaped cross section in the laminate along a line on which the laminate is to be severed, the indentation being of such depth as to extend through the full thickness of the plastic layer and through a part of the thickness of the metal layer, such that the plastic material along the line of the indentation is substantially displaced laterally; and severing the laminate along the line of the indentation in the metal layer.
The present invention further consists in an article consisting of a portion of a laminate of the type comprising a layer of a metal and a layer of a flexible synthetic plastic material which has been severed from a sheet of such laminate by the method according to this invention.
The present invention still further consists in apparatus for severing a laminate of the type including a layer of a metal and a layer of a deformable synthetic plastic material, the apparatus comprising means to form along a line of intended severance an indentation in a laminate of the said type, the indentation being of substantially channel-shaped cross section and being of such a depth as to extend through the full thickness of the plastic layer and through a part of the thickness of the metal layer, and means for severing the laminate along the line of the indentation in the metal layer.
As used in this specification the expression "an indentation of substantially channel-shaped cross sectional shape" means an indentation which, when seen in cross section, has a pair of side walls which are parallel or inclined towards one another and which
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patent: 3812002 (1974-05-01), Lurie
patent: 4386925 (1983-06-01), Focke
Kilgannon William F.
Precision Valve Australia Pty, Limited
Simmons David
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