Vacuum die mount

An apparatus for cutting paperboard sheets, comprising:

• a motor;
• means for controlling said motor;
• a die roll rotatably mounted for rotation by said motor, said die roll having a cylindrical surface;
• a cutting die having a rigid curved shell with at least one cutting rule mounted therein, said shell being mountable on said die roll surface;
• vacuum means for applying a vacuum between said surface and said die for drawing and holding said die against said surface;
• first and second sensor means, connected to said controlling means, for transmitting and receiving electromagnetic waves;
• a first reflector mounted on said die roll and covered in use by said die when mounted on said surface;
• a second reflector mounted on said die;
• said first sensor means functioning to cause said motor to be switched off if said first sensor means senses reflected electromagnetic waves from said first reflector;
• and
• said second sensor means functioning to cause said motor to be switched off if said second sensor means does not sense reflected electromagnetic waves from said second reflector.

Die mounting apparatus, comprising:

• a motor;
• a die cylinder mounted for rotation by said motor;
• a die mountable on an exterior surface of said die cylinder;
• means for generating a vacuum and being selectively switchable on or off;
• means for applying said vacuum between said surface and said die when mounted on said surface;
• a light reflector mounted on said die;
• and
• means for sensing light reflected from said reflector when said die cylinder is rotating, and for causing said motor to be switched off if said vacuum generating means is switched on and no reflected light is received by said sensing means.

A method of mounting on a die cylinder a cutting die having a wooden shell, comprising the steps of:

• locating a key on the die in an axial keyway in the die cylinder to position the die circumferentially on the die cylinder;
• then
• moving the die axially on the die cylinder and aligning a bolt hole in the die with a selected bore in the die cylinder to position the die axially on the die cylinder;
• then
• inserting a bolt through said bolt hole into said bore
• during said moving and inserting steps, causing a protruding but readily collapsible seal on said die to bridge gaps occurring between the die and the die cylinder due to the wooden shell of the die being distorted and not conforming exactly to the die cylinder, and causing said seal to define a closed area between said die and said die cylinder;
• and then
• applying vacuum to said closed area between the die and the die cylinder to draw the die towards and into surface conformity with the die cylinder and to flatten said seal.

A method of mounting and controlling use of a rotary cutting die, comprising the steps of:

• mounting a rotary cutting die on a die cylinder;
• applying vacuum between said die and said die cylinder to hold said die on said die cylinder;
• drivingly rotating said die cylinder while still applying said vacuum;
• transmitting first and second signals towards the rotating die and die cylinder;
• stopping said drivingly rotating of said die cylinder in response to absence of said first signal being reflected by a first reflector on said die;
• also stopping said drivingly rotating of said die cylinder in response to presence of said second signal being reflected by a second reflector on said die cylinder;
• and
• continuing said drivingly rotating of said die cylinder in response to said first signal being reflected by said first reflector and said second signal not being reflected by said second reflector.

A method of mounting a rotary cutting die, having a substantially rigid shell, on a rotatable die cylinder, comprising the steps of:

• placing said die on said die cylinder to be held thereon in use by application of vacuum between said die and said die cylinder;
• beginning rotation of said die cylinder with said die thereon;
• sensing whether a signal is coming from the rotating die;
• and
• stopping said rotation of said die cylinder in response to absence of said signal coming from said die when said application of vacuum has occurred.