APPARATUS FOR CHANGING THE LENGTH OF ENVELOPE BLANKS CUT FROM A CONTINUOUS WEB

• Main Authors: LAMBERT; MICHAEL P, WILKINSON; JASON H, SMITHE; ELIOT S
• Format: Patent
• Language: English
• Published: 07.09.1993
• Subjects: CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING,CUTTING-OUT, STAMPING-OUT OR SEVERING; HAND CUTTING TOOLS; PERFORMING OPERATIONS; SEVERING; TRANSPORTING

A pair of pull rolls unwind web material from a roll and advance the web at a preselected linear feed rate to a web cutting mechanism. The pull rolls are rotated at a preselected speed to generate the desired linear speed rate for cutting the web at selected intervals to produce blanks of a preselected length. The feed rolls are driven by a servo-motor which is operated by a controller that is microprocessor controlled. The controller is electrically connected to an encoder that is drivingly connected to a rotating knife cylinder of the web cutting mechanism. A selected length of blank to be cut from the web is inputted by the operator through a keypad to transmit a corresponding signal to the controller. In addition, the controller receives a signal from the servo-motor that drive the pull rolls, which signal is representative of the rate of rotation of the pull rolls. The inputs to the controller are compared to determine if the pull rolls are being rotated at the required speed to provide the linear feed rate that supplies the web to the cutter mechanism for producing blanks of a desired length. Should a deviation occur in the length of blank cut from the web, the controller detects the deviation and generates an output signal to the servo-motor to adjust the rate of rotation of the pull rolls. In addition, in the event a change in the length of blank cut from the web is desired, the operator changes the blank length and the controller responds by generating an output signal which adjusts the rate of rotation of the pull rolls in relationship to the position of the cutter mechanism.