Adhesive applicator for perfect bound books and method of applying adhesive

Apparatus for applying adhesive to the spine of a book block so that said book block to have a cover adhesively bound thereto along said spine, said apparatus comprising a head, said book block and said head being movable relative to one another toward and away from one another between an adhesive applying position in which said head is in operative relation with said spine so as to apply said adhesive to said spine and a retracted position in which said head is clear of said spine and further being movable relative to one another along a path substantially parallel to said spine of said book block, said adhesive being a solid member when at room temperature, said head having at least one heater for heating said adhesive to a flowable state for application to said spine, a drive which feeds said solid adhesive member into said head so as to be heated to said flowable state within said head, and a pump for effecting the dispensing of flowable adhesive from said head thereby to apply said adhesive to said spine as said book block and said head are moved relative to one another along said path, wherein said head having an end face adapted for the application of said flowable adhesive to said spine when said book block spine and said head are in operative relation with one another and when said book block and said head are moved along said path, said head having a slot across said end face with one portion of said head on one side of said slot extending axially out beyond another portion of said end face on the opposite side of said slot, said one portion of said head end face leads said slot relative to said relative to the direction of relative movement between said spine and said head during application of adhesive so that said other portion of said head is stepped back from said spine, and wherein said slot is in communication with said flowable adhesive within said head such that upon dispensing of said flowable adhesive said step back of said other portion of said head determines the thickness of said adhesive applied to said spine, wherein said book blocks range between a minimum and a maximum thickness, wherein the length of said slot is such that said slot extends across substantially the thickness of a spine of said maximum thickness book block, and wherein said head is rotatable about a horizontal axis from a first position in which said slot is generally perpendicular to said spine to an angled position so as to accommodate book block thicknesses ranging between said maximum thickness and a minimum thickness.