Real time machining process monitoring

Abstract

A pre-process simulation may calculate operating conditions of a machine tool by simulating a NC program and calculate predicted values indicative of the operating conditions. A real time monitoring system may compare actual values from the actual operation of a machine tool actually executing the NC program to the predicted values and determine whether to initiate a response. The operating conditions may be machine tool operating conditions. The comparison of actual values to predicted values may be based on a dynamic limit within which the predicted values fall which may vary based on the tool position, and the dynamic limit may include upper and lower limit boundaries.

1 . A machining system comprising a machine tool and a monitoring system,
 a. the machine tool configured:
 i. to move a tool carried by the machine tool along a tool path, the tool path comprising a plurality of sequential tool positions; 
 ii. to provide, to the monitoring system, for each respective tool position of a plurality of the plurality of sequential tool positions a respective actual value of each of at least one operating condition resulting from operation of the machine tool at that respective tool position; and 
   b. the monitoring system configured to compare each respective actual value of a plurality of the respective actual values to a respective predicted value of the at least one operating condition that corresponds to that respective tool position of the respective actual value.   
     
     
         2 . The machining system of  claim 1 , wherein the respective predicted value has an associated tool position, and the monitoring system is configured to select the respective predicted value by comparing the respective tool position to the associated tool position. 
     
     
         3 . The machining system of  claim 1 , wherein the respective predicted value has an associated tool position, and the monitoring system is configured to select the respective predicted value by selecting the respective predicted value of the associated tool position that is within a tolerance range of the respective tool position. 
     
     
         4 . The machining system of  claim 1 , wherein the respective predicted value has an associated tool position, and the monitoring system is configured to select the respective predicted value by selecting the respective predicted value of the associated tool position that is the closest to the respective tool position. 
     
     
         5 . The machining system of  claim 1 , wherein the plurality of sequential tool positions are consecutive tool positions. 
     
     
         6 . The machining system of  claim 1 , wherein the machine tool is configured to move the tool along the tool path by execution of a program comprising a plurality of respective motion steps, each tool position of a plurality of the plurality of sequential tool positions corresponding to a respective motion step. 
     
     
         7 . The machining system of  claim 1 , wherein the monitoring system is configured to send a command to the machine tool if any respective actual value falls outside of a range which contains the respective predicted value. 
     
     
         8 . The machining system of  claim 1 , comprising a computer configured to calculate a plurality of the predicted values value by simulating operation of the machine tool. 
     
     
         9 . The machining system of  claim 1 , wherein the monitoring system is configured to compare a plurality of the respective actual values to respective predicted values that do not correspond to a respective tool position. 
     
     
         10 . A method of operating a machine tool, the method comprising:
 a. moving a tool carried by the machine tool along a tool path, the tool path comprising a plurality of sequential tool positions;   b. comparing a respective actual value of each of at least one respective operating condition experienced by said machine tool during operation of the machine tool at each respective tool position of a plurality of the plurality of sequential tool positions to a respective predicted value of the at least one operating condition that corresponds to that respective tool position of the respective actual value.   
     
     
         11 . The method of  claim 10 , wherein the respective predicted value has an associated tool position, and wherein the step of comparing comprises selecting the respective predicted value by comparing the associated tool position to the respective tool position. 
     
     
         12 . The method of  claim 10 , wherein the respective predicted value has an associated tool position, and wherein the step of comparing comprises selecting the respective predicted value of the associated tool position that is within a tolerance range of the respective tool position. 
     
     
         13 . The method of  claim 10 , wherein the respective predicted value has an associated tool position, and wherein the step of comparing comprises selecting the respective predicted value of the associated tool position that is closest to the respective tool position. 
     
     
         14 . The method of  claim 10 , wherein the step of moving a tool along a tool path comprises executing a plurality of motion steps corresponding to a NC program, each respective tool position corresponding to a respective motion step. 
     
     
         15 . The method of  claim 10 , wherein the step of comparing comprises comparing a plurality of the respective actual values to respective predicted values that do not correspond to a respective tool position. 
     
     
         16 . The method of  claim 10 , comprising calculating each respective predicted value by simulating operation of the machine tool. 
     
     
         17 . The method of  claim 10 , wherein the step of moving a tool comprises executing a program which comprises a plurality of motion steps, and comprising calculating each respective predicted value by simulating execution of the plurality of motion steps. 
     
     
         18 . The method of  claim 10 , wherein the step of comparing comprises comparing the at least one respective actual value to a respective range containing the respective predicted value. 
     
     
         19 . The method of  claim 10 , comprising sending a command to the machine tool if any respective actual value falls outside of a range which contains the respective predicted value. 
     
     
         20 . The method of  claim 19 , comprising implementing a remedial action in response to a command. 
     
     
         21 . The method of  claim 10 , wherein the respective operating condition comprises machine tool operating condition. 
     
     
         22 . The method of  claim 10 , wherein the respective operating condition is selected from the group consisting of radial load on a tool holder of the machine tool, bending moment on the tool holder, bending moment at the tool holder/spindle interface, spindle power, torque of the machine tool, load on one or more axis servo of the machine tool and temperature of the tool. 
     
     
         23 . A method of simulating operation of a machine tool, the method comprising:
 a. simulating execution of a plurality of motion steps corresponding to a NC program; and   b. for at least one respective simulated operating condition corresponding to each respective one of a plurality of the plurality of motion steps, calculating at least one respective predicted value for each of the at least one simulated operating condition, wherein at least one of the simulated operating conditions comprises a simulated machine tool operating condition.   
     
     
         24 . The method of  claim 23 , wherein the step of simulating execution of a plurality of motion steps is executed in a sequence of one motion step at a time and the step of calculating at least one respective predicted value is executed for one of the plurality of motion steps before proceeding to the next motion step of the sequence. 
     
     
         25 . The method of  claim 23 , comprising for each motion step simulated the step of determining whether any predicted value for that motion step exceeds a limit which is relevant to the simulated operating condition of that predicted value. 
     
     
         26 . The method of  claim 23 , comprising revising the NC program if any predicted value exceeds the limit. 
     
     
         27 . The method of  claim 23 , wherein the simulated machine tool operating condition is selected from the group consisting of simulated radial load on a tool holder of the machine tool, simulated bending moment on the tool holder, simulated bending moment at the tool holder/spindle interface, simulated torque of the machine tool, and simulated load on one or more axis servo of the machine tool. 
     
     
         28 . A machine comprising a computer configured to:
 a. simulate operation of a machine tool by modeling the execution of a plurality of motion steps corresponding to a NC program;   b. for at least one respective simulated operating condition corresponding to each respective one of a plurality of the plurality of motion steps, calculate at least one respective predicted value for each of the at least one respective simulated operating condition, wherein at least one of the simulated operation conditions comprises a simulated machine tool operation condition.