Method and apparatus for cutting sheet material with improved accuracy

An automatically controlled cutting machine for cutting sheet material comprising:

• a cutting table including a cutting tool and a support surface on which sheet material is held during a cutting operation;
• motive means responsive to machine command signals for moving the sheet material and cutting tool relative to one another in cutting engagement;
• computing means receiving data defining desired cutting paths in the sheet material for generating machine command signals which produce the desired cutting paths from the received data, said computing means also including an optional program memory having a program of biassing signals for combination with the machine command signals;
• and means for selecting the optional program.

A method of cutting pattern pieces from sheet material with an automatically controlled cutting machine having a cutting blade in accordance with marker data defining the pattern pieces comprising:

• generating in a data processor from the marker data displacement signals for translating the cutting blade and the sheet material relative to one another along a cutting path;
• calculating in the data processor from the marker data blade rotation signals for orienting the cutting blade to a position in alignment with the cutting path at each point along the path;
• establishing an optional yaw program for adding yaw signals to said blade rotation signals in order to generate machine command signals which bias the cutting blade slightly out of alignment with the cutting path during the cutting operations;
• storing the yaw program in a memory device associated with the data processor;
• selectively activating the optional, stored yaw program in the memory device from a selector on the cutting machine to obtain yaw signals and combining the yaw signals with the calculated balde rotation signals to produce modified blade rotation signals;
• and
• advancing the cutting blade and the sheet material relative to one another along the cutting path in cutting relationship in accordance with the displacement and modified blade rotation signals to cut the pattern pieces from the sheet material.

In an automatically controlled cutting machine having a cutting blade and a table on which sheet material is supported while the blade and sheet material are moved relative to one another in response to machine commands developed from data defining pattern pieces to be cut from the sheet material, the improvement comprising:

• first computing means responsive to said data for generating displacement signals to control translation of the cutting blade and sheet material relative to one another along cutting paths corresponding to the shape of the pattern pieces;
• second computing means also responsive to said data to determine blade rotation signals for orienting the blade along the cutting path in the direction of the path;
• memory means for storing an optional yaw program defining yaw signals to be added by the second computing means to the blade rotation signals to rotate the cutting blade slightly away from the direction of the cutting path;
• and
• selector means operatively connected with the memory means for optionally engaging the memory means with the second computing means and introducing the yaw signals into the second computing means,
• the second computing means also being responsive to the introduced yaw signals and including means for combining the yaw signal with the blade rotation signals to produce modified blade rotation signals.