Cutting carton blanks and cutters therefor

Apparatus for slotting paperboard sheets, comprising:

• a first rotatable slotting head having a slotting groove therein and an anvil surface to one side of said groove;
• a second rotatable slotting head having a slotting blade extending radially therefrom and intermittently engageable in said groove for cutting slots in paperboard sheets fed between said heads;
• said second head having a knife extending transversely to said slotting blade and intermittently cooperating with said anvil surface for making in said paperboard sheets cuts extending transversely from said slots;
• a scallop-like cut-out in a side of said blade nearest said anvil surface, said cut-out being intermediate leading and trailing edges of said blade and reducing in thickness a portion of a double edged, radially outer cutting surface of said blade, said cut-out enabling an integral scrap portion to be cut from each paperboard sheet by said blade and said knife;
• said groove having opposed side walls with radial channels formed therein to aid gripping of part of said integral scrap portion by said groove;
• removing means, engaging in said groove, for removing said part of said scrap portion therefrom;
• and
• conveyor means for conveying away from said removing means said integral scrap portion after said part of said scrap portion has been removed from said groove.

A method of cutting an end portion of a carton blank, comprising the steps of:

• cutting a slot in the carton blank adjacent one end of the carton blank, the slot having a lengthwise direction and being incomplete on one side for a portion of the length thereof;
• making a cut in said carton blank transverse to said direction;
• said slot cutting and cut making steps together severing from the carton blank an integral piece of scrap comprising a strip portion connected to another portion by a bridging piece created by said slot being incomplete on said one side for said portion of the length thereof;
• and
• collecting said integral piece of scrap.

A method of controlling scrap when forming a carton blank with a stitch flap, comprising the steps of:

• scoring a carton blank to define side panels thereof;
• slotting the carton blank to define end flaps thereof;
• said slotting including cutting a slot in a lengthwise direction in the carton blank adjacent one end of the carton blank by passing the carton blank between a rotating slot cutting blade and a rotating slot cutting groove;
• making a cut in said carton blank transverse to said direction, said cut extending from said slot to said one end of the carton blank to define one side of a stitch flap and also to define a portion of scrap at said one end of the carton blank between said slot and said cut;
• said cutting a slot being performed by two cutting edges of said blade cooperating with opposite cutting edges of said groove, said blade entering said groove to cut a strip from said carton blank and force said strip into said groove;
• said cutting a slot also including leaving an uncut part along a portion of a side of said slot between said strip and said portion of scrap, said uncut part being enabled by a cut-out in a side of said blade immediately adjacent said portion of scrap, said uncut part forming a bridging piece integrally connecting said portion of scrap to said strip;
• allowing edges of said strip to key into radial channels in opposing sides of said groove to enable said groove to positively grip said strip;
• moving said strip so gripped by said groove by rotating of said groove;
• stripping said strip out of said groove;
• and
• allowing said strip with said portion of scrap integrally connected thereto to fall onto a conveyor.