Vacuum lifter

Abstract

A vacuum plate lifting system for lifting sheet material articles comprises a vacuum lifter apparatus for lifting sheet material articles, a lifter actuation system configured to lift and/or move the vacuum lifter apparatus during use and a control system, the control system being configured to control the lifter actuation system during said movement. The vacuum lifter apparatus comprises: a substantially horizontal suction plate comprising a perforated suction lifting surface, said surface being downwardly oriented for making contact with an upper surface of said articles to be lifted, an airflow suction system for conveying vacuum air pressure to said perforated suction lifting surface; and at least one mount for connection of the suction plate to at least one actuator of the lifter actuation system for lifting and/or moving the suction plate during use. There is at least one suction lifter proximate an edge of the suction plate, said suction lifter comprising a downwardly oriented suction cup, said cup being movably mounted in a substantially vertical direction relative to the suction plate and being connected to a source of air pressure for providing air suction to said cup for plucking upwards a local area of said of articles to be lifted. A suction cup actuation system is configured to drive said movement of the suction cup between a raised orientation in which the suction cup is raised relative to a level of said suction lifting surface and a lowered orientation in which the suction cup is substantially at or below the level of said suction lifting surface whereby, in use, said air suction is directed substantially downwardly towards a sheet material article to be lifted when said suction cup is in the lowered orientation. The control system is operable to control the operation of the lifter actuation system and the operation of the suction cup actuation system to initially pluck said local area of said article to be lifted prior to applying said vacuum air pressure to said perforated suction lifting surface to lift the remainder of said article.

1 . A vacuum plate lifting system, comprising a vacuum lifter apparatus for lifting sheet material articles, and a control system, the control system being configured to control the vacuum lifter apparatus during said lifting of sheet material articles, the vacuum lifter apparatus comprising:
 a substantially horizontal suction plate comprising a substantially planar perforated suction lifting surface extending across said suction plate, said suction lifting surface being downwardly oriented for making planar contact with an upper surface of said articles to be lifted;   an airflow suction system for conveying vacuum air pressure to said suction lifting surface;   at least one suction lifter proximate an edge of the suction plate, said suction lifter comprising a downwardly oriented suction cup, said cup being movably mounted in a substantially vertical direction relative to the suction plate and being connected to a source of air pressure for providing air suction to said cup for plucking upwards a local area of said of articles to be lifted; and   a suction cup actuation system including an actuator configured to drive substantially vertical movement of the suction cup between a raised orientation in which the suction cup is raised relative to a level of said suction lifting surface and a lowered orientation in which the suction cup is substantially at or below the level of said suction lifting surface whereby, in use, said air suction is directed substantially downwardly beneath said suction lifting surface towards a sheet material article to be lifted when said suction cup is in the lowered orientation;   wherein the control system is operable to control the actuator of the suction cup actuation system to position the suction cup in the lowered orientation for initially plucking said local area of said article to be lifted and subsequently to position the suction cup in the raised orientation in order to transfer said local area into said contact with said suction lifting surface.   
     
     
         2 . A vacuum plate lifting system as claimed in  claim 1 , in which the actuator of the suction cup actuation system comprises a vertically oriented slideable member to which the suction cup is mounted. 
     
     
         3 . A vacuum plate lifting system as claimed in  claim 1  or  claim 2 , in which the control system is operable to independently control: (1) the actuator of the suction cup actuation system; and (2) the source of air pressure for providing air suction to said cup. 
     
     
         4 . A vacuum plate lifting system as claimed in any preceding claim, in which the suction cup is raised up to or above the level of said suction lifting surface when in the raised orientation. 
     
     
         5 . A vacuum plate lifting system as claimed in any preceding claim, further comprising a lifter actuation system configured to lift and/or move the vacuum lifter apparatus during use, the control system being configured to control the lifter actuation system during said lifting and/or movement of the vacuum lifter apparatus. 
     
     
         6 . A vacuum plate lifting system as claimed in  claim 5 , in which the vacuum lifter apparatus further comprises at least one mount for connection of the suction plate to at least one actuator of the lifter actuation system for lifting and/or moving the suction plate during use. 
     
     
         7 . A vacuum plate lifting system as claimed in any preceding claim, in which the suction lifter extends downwardly through an aperture in said suction lifting surface, and is recessed within said aperture when in the raised orientation. 
     
     
         8 . A vacuum plate lifting system as claimed in any preceding claim, in which the suction plate has a substantially square or rectangular profile in a horizontal plane, and there are three of said suction lifters with two of said lifters being mounted along adjacent edges of the suction plate proximate a corner of said profile and a third one of said lifters is mounted proximate a vertex of said profile between said adjacent edges. 
     
     
         9 . A vacuum plate lifting system as claimed in any preceding claim, in which the suction plate is composed of a plurality of adjacent suction modules, each module providing a portion of said perforated suction lifting surface, and the airflow suction system is configured to convey vacuum air pressure to each of said portions via corresponding control valves, the control system being configured to control the operation of said valves to individually control the vacuum air pressure provided to each of said portions. 
     
     
         10 . A vacuum plate lifting system as claimed in  claim 9 , in which said portions of said perforated suction lifting surface include a proximal set of portions relatively closer to said suction lifter and a distal set relatively further away from said suction lifter, and the control system being configured to sequence the operation of said valves to provide said vacuum air pressure to said proximal portion prior to said distal portion following said initial plucking of said local area. 
     
     
         11 . A vacuum plate lifting system as claimed in any preceding claim, in which the actuator is a bellows actuator which pulls upwards a piston on which said suction cup is mounted, said piston being spring biased to the lowered orientation. 
     
     
         12 . A method of using a vacuum plate lifting system, the vacuum plate lifting system comprising:
 a vacuum lifter apparatus for lifting sheet material articles;   at least one suction lifter proximate an edge of a suction plate, said suction lifter comprising a downwardly oriented suction cup, said cup being movably mounted in a substantially vertical direction relative to the suction plate and being connected to a source of air pressure for providing air suction to said cup for plucking upwards a local area of said of articles to be lifted;   an airflow suction system for conveying vacuum air pressure to a substantially planar perforated planar suction lifting surface;   a suction cup actuation system configured to actively drive said movement of the suction cup between a raised orientation in which the suction cup is raised relative to a level of said suction lifting surface and a lowered orientation in which the suction cup is substantially at or below the level of said suction lifting surface whereby, in use, said air suction is directed substantially downwardly towards a sheet material article to be lifted when said suction cup is in the lowered orientation; and   a control system for controlling the suction cup actuation system;   wherein the method comprises the steps of:   using the control system to control the movement of said suction cup by the suction cup actuation system to place said suction cup in the lowered orientation;   with the suction cup in the lowered orientation and with said suction lifting surface over said sheet material article to be lifted, applying said air suction to said suction cup to pluck upwards a local area of said of said article to be lifted;   using the control system to control the movement of said suction cup by the suction cup actuation system to place said suction cup in the raised orientation once the airflow suction system is being used or is about to be used to lift the remainder of said article to said suction lifting surface; and   with said local area being first being lifted by said suction cup, using the airflow suction system to convey vacuum air pressure to the suction lifting surface to lift the remainder of said article to said suction lifting surface.   
     
     
         13 . A method as claimed in  claim 12 , in which the vacuum plate lifting system further comprises a lifter actuation system configured to lift and/or move the vacuum lifter apparatus during use, and the method comprises using the controller to control the lifter actuation system when said sheet material articles are to be lifted to position said suction lifting surface over a sheet material article to be lifted. 
     
     
         14 . A method as claimed in  claim 12  or  claim 13 , in which said suction lifter extends downwardly through an aperture in said suction lifting surface and the method comprises withdrawing said suction cup inside said aperture when the remainder of said article is lifted or is about to be lifted to said suction lifting surface. 
     
     
         15 . A method as claimed in any one of  claims 12  to  14 , further comprising using the control system to control the operation of valves to individually control the vacuum air pressure provided to each of several portions of said suction lifting surface during lifting of the remainder of said article to said suction lifting surface. 
     
     
         16 . A method as claimed in  claim 15 , in which the control system is configured to sequence the operation of said valves to provide said vacuum air pressure to a portion of said suction lifting surface relatively closer to said suction cup prior to providing said vacuum air pressure to a portion of said suction lifting surface relatively farther away from said suction cup. 
     
     
         17 . A method as claimed in any one of  claims 12  to  16 , in which the suction plate is composed of a plurality of adjacent suction modules, each module providing a portion of said perforated suction lifting surface, and the method comprises using the airflow suction system to convey vacuum air pressure to each of said portions via corresponding control valves, the control system being configured to control the operation of said valves to individually control the vacuum air pressure provided to each of said portions in a progressive manner such that subsequent lifting of as yet un-lifted portions of the sheet material article is directed away from the initially lifted localised area.