Method of grinding a workpiece and method for determining processing parameters

A method of determining processing parameters of a grinding method for grinding a workpiece, which is rotated about a rotational axis, by means of an essentially rotationally symmetrical grinding wheel, the grinding method comprising a first stage and a second stage, wherein the method of determining the processing parameters comprises iterating the first and the second stage of the grinding method by the following steps:

• a. selecting a total stock to be removed (δ) from the workpiece as the stock removed in the first stage (δ1);
• b. calculating a number of feed increments in the first stage (n1) with a corresponding depth of cut (ae1) for each increment in the first stage for achieving the stock removed in the first stage (δ1) while controlling an instantaneous workpiece rotational speed with the purpose of maintaining a pre-selected maximum surface temperature (θ*) of the workpiece;
• c. calculating a grinding cycle time (tj) resulting from the number of feed increments of the first stage and the instantaneous workpiece rotational speed obtained in step b;
• d. in case the grinding cycle time (tj) obtained in step c is equal to or less a grinding time (tj-1) which would be achieved for a grinding cycle comprising one less increment in the first stage, repeating steps b and c for a grinding cycle comprising one additional increment until the grinding time obtained is greater than a grinding time for a grinding cycle comprising one less increment, thereby obtaining a calculated instantaneous workpiece rotational speed for the first stage, a calculated number of feed increments for the first stage (n1) and a calculated depth of cut (ae1) for each increment in the first stage;
• e. calculating a stock removal (δ2) of the second stage using the calculated instantaneous workpiece rotational speed obtained from step d, a pre-selected number of feed increments (n2) in the second stage and a pre-identified aggressiveness number indicating a force of grinding of the second stage corresponding to a depth of cut (ae2) during the second staged;
• f. calculating the stock removal in the first stage (δ1) by subtracting the stock removal in the second stage (δ2) from the total stock removal (δ) from the workpiece;
• and
• g. repeating steps b to f using the stock removal of first stage (δ1) obtained in step f until the same stock removal (δ1) for the first stage is achieved in step f as in the previous iteration of the first and second stage,
• thereby determining the instantaneous workpiece rotational speed, the number of feed increments in the first stage (n1), the depth of cut (ae1) in each feed increment in the first stage and the depth of cut (ae2) in each feed increment in the second stage.

A computer program product for determining processing parameters of a grinding method, wherein said computer program product comprises computer program instructions stored on a non-transitory computer readable medium readable by a computer to cause one or more computer processors to perform the operations of:

• a. selecting a total stock to be removed (δ) from the workpiece as the stock removed in the first stage (δ1) (S1);
• b. calculating a number of feed increments in the first stage (n1) with a corresponding depth of cut (ae1) for each increment in the first stage for achieving the stock removed in the first stage (δ1) while controlling an instantaneous workpiece rotational speed with the purpose of maintaining a pre-selected maximum surface temperature (θ*) of the workpiece (S2);
• c. calculating a grinding cycle time (tj) resulting from the number of feed increments of the first stage and the instantaneous workpiece rotational speed obtained in step b (S3);
• d. in case the grinding cycle time (tj) obtained in step c is equal to or less a grinding time (tj-1) which would be achieved for a grinding cycle comprising one less increment in the first stage, repeating steps b and c for a grinding cycle comprising one additional increment until the grinding time obtained is greater than a grinding time for a grinding cycle comprising one less increment, thereby obtaining a calculated instantaneous workpiece rotational speed for the first stage, a calculated number of feed increments for the first stage (n1) and a calculated depth of cut (ae1) for each increment in the first stage (S4);
• e. calculating a stock removal (δ2) of the second stage using the calculated instantaneous workpiece rotational speed obtained from step d, a pre-selected number of feed increments (n2) in the second stage and a pre-identified aggressiveness number indicating a force of grinding of the second stage corresponding to a depth of cut (ae2) during the second stage (S5);
• f. calculating the stock removal in the first stage (δ1) by subtracting the stock removal in the second stage (δ2) from the total stock removal (δ) from the workpiece (S6);
• and
• g. repeating steps b to f using the stock removal of first stage (δ1) obtained in step f until the same stock removal (δ1) for the first stage is achieved in step f as in the previous iteration of the first and second stage (S7),
• thereby determining the instantaneous workpiece rotational speed, the number of feed increments in the first stage (n1), the depth of cut (ae1) in each increment in the first stage and the depth of cut (ae2) in each increment in the second stage.