Dual speed limits for a cut-off

• US 5,713,256 A
• Filed: 03/09/1994
• Issued: 02/03/1998
• Est. Priority Date: 03/09/1994
• Status: Expired due to Fees

• Current Assignee: Sun Automation Inc.
• Original Assignee: The Langston Corporation
• Inventors: Keeny, Thomas R.
• Primary Examiner(s): Peterson, Kenneth E.
• Application Number:
  US08/208,758
• Time in Patent Office: 1,427 Days
• Field of Search: 83/311, 83/342, 83/343, 83/345, 83/363, 83/110, 83/26, 83/38, 83/76, 83/324, 83/354
• US Class Current: 83/26
• CPC Class Codes: B26D 1/626 for thin material, e.g. for sheets, strips or the like
• CPC Class Codes: B26D 5/00 Arrangements for operating and controlling machines or devices for cutting, cutting-out, stamping-out, punching, perforating, or severing by means other than cutting
• CPC Class Codes: B26D 5/20 with interrelated action between the cutting member and work feed
• CPC Class Codes: B65H 35/08 from or with revolving, e.g. cylinder, cutters or perforators
• CPC Class Codes: Y10T 83/0462 By accelerating travel
• CPC Class Codes: Y10T 83/0519 Cyclically varying rate of tool or work movement
• CPC Class Codes: Y10T 83/159 Including means to compensate tool speed for work-feed variations
• CPC Class Codes: Y10T 83/2094 Means to move product at speed different from work speed
• CPC Class Codes: Y10T 83/4775 Tool speed varied within each orbital cycle
• CPC Class Codes: Y10T 83/4827 With helical cutter blade

Abstract

A direct drive cut-off has a pair of cylinders, each having a helical knife blade. The path of the knife blade around the cylinder defines a synchronous length. A corrugated board is passed in a board path direction between the cylinders at a production rate. The knife blades move in proximity to each other in the board direction to cut the continuous board into sheets. The knife blades enter the board path and engage the continuous board at a beginning of engagement position of a knife blade entering edge and depart the board path at an end of engagement position of a knife blade exiting edge. The sheets are accelerated downstream of the cylinders. The cylinders are controlled by a control unit for accelerating and decelerating the rotational speed of the cylinders so that the knife blades engage the continuous board at the specific length cutting the board into sheets. The control unit is responsive to the production rate, and the sheet length. Therefore, for sheets that are shorter than the synchronous length, when the production rate is above a set speed, the control unit accelerates the cylinders after the knife blades complete the cut but before blade engagement is complete so that the knife blades do not engage the accelerating sheet. For production rates below the set speed and sheets shorter than the synchronous length, the control unit accelerates the cylinders when the knife blades reach the end of engagement position of the knife blade exiting edge.

Claims

1. A method for cutting sheets of a preselected length from a continuous web, comprising the following steps:

providing a direct drive cut-off having a pair of cylinders, each of the cylinders having a knife blade, the path of the knife blade around the cylinder defining a synchronous length;

passing the continuous web in a web path direction through a web path between the cylinders at a production rate;

rotating the cylinders in opposite directions so that the knife blades move in proximity to each other in the web direction to cut the continuous web into sheets such that the knife blades engage the web path and continuous web at a beginning engagement position, depart the web path at an end engagement position, and complete the cut prior to the end engagement position;

accelerating the sheets downstream of the cylinders; and

controlling the cylinders by a control means for accelerating and decelerating the rotational speed of the cylinders so that the knife blades engage the continuous web at the preselected length cutting the web into sheets, the control means being responsive to the production rate and the desired sheet length so that for sheets that are shorter than the synchronous length, the control means accelerates the cylinders after the knife blades complete the cut but before the knife blades reach the end engagement position when the production rate is above a set speed, and begins accelerating the cylinders when the knife blades reach the end engagement position for production rates below the set speed.

2. A method for increasing the production rate of cutting sheets of a specific length from a continuous web as in claim 1 wherein the sheet accelerating means is driven at a constant rate above the production rate.

3. A method for increasing the production rate of cutting sheets of a specific length from a continuous web as in claim 1 wherein the sheet accelerating means is accelerated when the knife blades complete the cut but before blade engagement is complete.

4. A method for cutting a continuous board moving through a cutting apparatus into sheets of preselected length comprising:

rotating a pair of driven knife blade cylinders having helically mounted knife blades for cutting the continuous board into sheets in opposite directions in synchronization with each other so that the knife blades begin making a cut across the board at one edge of the board and end the cut at the opposite edge of the board, the knife blades clearing the path of the board after the end of the cut at an end engagement position;

accelerating the sheets cut from the board to a speed greater than the speed at which the board is traveling, creating a gap between the board and each successive cut sheet; and

accelerating the rotational speed of the knife blade cylinders to cut the board into sheets having a length less than a synchronous length of the knife blade cylinders such that i) when the speed at which the board is traveling is greater than a preselected speed, the controller accelerates the cylinders after the board is cut, but before the knife blades reach the end engagement position, and ii) when the speed at which the board is traveling is less than the preselected speed, the controller begins accelerating the cylinders after the end engagement position is reached.