Apparatus for decorating pressed tins

Claim 1

An apparatus for decorating pressed tine by printing a distorted image on a blank which is to be pressed but avoids the distortion of the decoration on the sidewall of the tin which may result from nonlinearity of the distortion of the metal and from the anisotropic character of the metal comprising an anamorphic device and a photographic apparatus in which the anamorphic device comprises in combination a truncated cone of transparent optical material having a perforation along an internal wall in the form of a cylinder, the cross section of which is geometrically similar to the cross section of the tin which is to be formed, and an external wall which is in the form of a truncated cone, the two bases of which are similar to the section of the internal cylinder and a correcting lens, the contour of which is geometrically similar to the cross section of the tin to be formed and which provides distortions which correspond to the distortions of the tin to be formed.

Claim 2

An apparatus for decorating pressed tine by printing a distorted image on a blank which is to be pressed but avoids the distortion of the decoration on the sidewall of the tin which may result from nonlinearity of the distortion of the metal and from the anisotropic character of the metal comprising an anamorphic device and a photographic apparatus in which the anamorphic device comprises in combination a truncated cone of transparent optical material having a perforation along an internal wall in the form of a cylinder, the cross section of which is geometrically similar to the cross section of the tin which is to be formed, and an external wall which is in the form of a truncated cone, the two bases of which are similar to the section of the internal cylinder and a correcting lens, the contour of which is geometrically similar to the cross section of the tin to be formed and which provides distortions which correspond to the distortions of the tin to be formed.

Claim 3

An apparatus for decorating pressed tins by printing a distorted image on a blank which is to be pressed but avoids the distortion of the decoration on the sidewall of the tin which may result from nonlinearity of the distortion of the metal and from the anisotropic character of the metal comprising an anamorphic device and a photographic apparatus in which the anamorphic device comprises in combination a truncated cone of transparent optical material having a perforation along an internal wall in the form of a cylinder, the cross section of which is geometrically similar to the cross section of the tin which is to be formed, and an external wall which is in the form of a truncated cone, the two bases of which are similar to the section of the internal cylinder and a correcting lens having a central zone formed of a strip with parallel surfaces geometrically similar to the shape of the tin to be formed and a peripheral zone obtained by pressing an experimental tin from a blank on which a checkered design is drawn, said tin enabling the curves of elongation of the metal to be traced as a function of the abscissa x of the given point taken on the blank by noting at each point of the sidewall of this tin the difference Delta H between the theoretical uniform elongation and the real elongation and then calculating the inclination A of the tangent at each point to the surface of the correcting lens according to the formula: A (1/n-1) ( Delta H/L) in which L is the distance of the given point on the correcting lens from the corresponding point of the image given by the truncated cone.

Claim 4

An apparatus for decorating pressed tins by printing a distorted image on a blank which is to be pressed but avoids the distortion of the decoration on the sidewall of the tin which may result from nonlinearity of the distortion of the metal and from the anisotropic character of the metal comprising an anamorphic device and a photographic apparatus in which the anamorphic device comprises in combination a truncated cone of transparent optical material having a perforation along an internal wall in the form of a cylinder, the cross section of which is geometrically similar to the cross section of the tin which is to be formed, and an external wall which is in the form of a truncated cone, the two bases of which are similar to the section of the internal cylinder and a correcting lens having a central zone formed of a strip with parallel surfaces geometrically similar to the shape of the tin to be formed and a peripheral zone obtained by pressing an experimental tin from a blank on which a checkered design is drawn, said tin enabling the curves of elongation of the metal to be traced as a function of the abscissa x of the given point taken on the blank by noting at each point of the sidewall of this tin the difference Delta H between the theoretical uniform elongation and the real elongation and then calculating the inclination A of the tangent at each point to the surface of the correcting lens according to the formula: A (1/n-1) ( Delta H/L) in which L is the distance of the given point on the correcting lens from the corresponding point of the image given by the truncated cone.