Vacuum plate, sheet material handling apparatus comprising such vacuum plate, and method for making the plate

A vacuum sheet material handling apparatus for handling sheet material, comprising a vacuum plate and a source of vacuum pressure, the vacuum plate comprising a first wall, a plurality of vacuum holes in the first wall each of said holes being defined by a bore extending through the first wall between opposite first and second sides of the first wall, the source of vacuum pressure being configured to apply a vacuum pressure to said bores from the second side of the first wall, whereby the first wall provides, in use, a vacuum surface for pulling and holding said article to the vacuum surface when said vacuum pressure is applied to said bores, wherein said bore comprises:

• a flared entrance terminating at the vacuum surface for admitting air pulled through said bore by said applied vacuum pressure;
• opposite said entrance, an exit for said air pulled through said bore, said exit being surrounded by a rim that extends above a surrounding surface of the second side of the first wall;
• and
• the source of vacuum pressure being connected to said at least one air outlet for applying said vacuum pressure from the second side of the first wall.

A vacuum sheet material handling apparatus for handling sheet material, comprising a vacuum plate and a source of vacuum pressure, the vacuum plate comprising a first wall, a plurality of vacuum holes in the first wall each of said holes being defined by a bore extending through the first wall between opposite first and second sides of the first wall, and at least one air outlet for connection to a source of vacuum pressure for applying a vacuum pressure to said bore from the second side of the first wall whereby the first wall provides, in use, a vacuum surface for pulling and holding said article to the vacuum surface when said vacuum pressure is applied to said bore, wherein said bore comprises:

• a flared entrance terminating at the vacuum surface for admitting air pulled through said bore by said applied vacuum pressure;
• and
• opposite said entrance, an exit for said air pulled through said bore, said exit being surrounded by a rim that extends above a surrounding surface of the second side of the first wall;
• wherein the source of vacuum pressure is connected to said at least one air outlet for applying said vacuum pressure from the second side of the first wall.

A method of making a vacuum plate for handling a sheet material article, the vacuum plate comprising a first wall, a plurality of vacuum holes in the first wall each one of said holes being defined by a bore extending through the first wall between opposite first and second sides of the first wall, and at least one air outlet for connection to a source of vacuum pressure for applying a vacuum pressure to said bores from the second side of the first wall, the first wall providing, in use, a vacuum surface for pulling and holding said article to the vacuum surface when said vacuum pressure is applied to said bores, wherein the method comprises:

• holding a metallic sheet between at least one aligned punch and die, the metallic sheet having opposite first and second sides and the punch extending along a punch axis and comprising around said axis:
• (i) a substantially V-shaped tip;
• (ii) extending axially away from the V-shaped tip a middle portion being substantially parallel with said axis;
• (iii) extending axially away from the middle portion, an expanded portion having a profile that flares away from said axis;
• and (iv) at the end of the expanded portion an axially extending step;
• pressing the V-shaped tip of the punch into the first side of said held metallic sheet along a punching direction aligned with an axis of the die to pierce the metallic sheet and start to draw material of the metallic sheet into a die recess around said bore pierced through the metallic sheet;
• continue to press the punch along said punching direction as the middle portion of the punch enters said bore until said profile of the expanded portion of the punch impresses an expanded entrance around said bore, the clearance between the middle portion of the punch and the die recess being sufficient such that said drawn material forms a rim of said bore, said rim being raised relative to a surrounding surface of the second side of the metallic sheet around said bore, and;
• continue to press the punch along said punching direction until the axially extending step of the punch impresses a step around said expanded entrance, thereby axially recessing said expanded entrance relative to the surface of the metallic sheet surrounding the bore;
• withdrawing the punch from the bore;
• repeating, if necessary, the above steps to create said plurality of bores in said metallic sheet, and then using said metallic sheet to provide said first wall in the vacuum plate with the first side of the metallic sheet providing the first side of the first wall, so that when said at least one air outlet is connected to a source of vacuum pressure, the first side of the first wall provides, in use, a vacuum surface for pulling and holding sheet material articles to the vacuum surface.