Motor Spindle Safety System

The most com­mon acci­dents involv­ing the use of machine tools include spin­dle crash­es. Com­mon caus­es include pro­gram­ming errors, incor­rect­ly defined tools, dis­re­gard­ed inter­fer­ence con­tours, or unin­ten­tion­al high-speed oper­a­tion. The forces involved are so enor­mous that com­po­nents of the motor spin­dle, ceram­ic spin­dle bear­ings, shafts, encoders, clamp­ing sys­tem and the entire machine geom­e­try can be affect­ed or even com­plete­ly destroyed.

A case study from RWTH Aachen shows that repair costs after a crash in the amount of five-dig­it euro amounts are not uncom­mon. Col­li­sion avoid­ance sys­tems for machine tools min­i­mize dam­age and reduce down­time and repair costs in the event of a col­li­sion. Nev­er­the­less, only very few machine tools have a spin­dle col­li­sion pro­tec­tion at all. This is usu­al­ly based on com­pres­sion ele­ments that act like a car bumper and are com­plete­ly destroyed in the event of a crash. Although the spin­dle com­po­nents remain intact, down­time still occurs.

The motor spin­dle pro­tec­tion sys­tem MS³ from Jakob Antrieb­stech­nik detects col­li­sions by means of sev­er­al sen­sors and reports them elec­tron­i­cal­ly to the machine con­trol. This can bring the feed axes of the machine tool to a halt with mea­sures such as brak­ing and revers­ing the dri­ves. But beyond that, the motor spin­dle pro­tec­tion sys­tem can imme­di­ate­ly inter­rupt the pow­er flow at the inter­face between the spin­dle box and the motor spin­dle by means of 3D deflec­tion in the event of a col­li­sion-induced over­load, even before the elec­tron­ic emer­gency stop, mechan­i­cal­ly and ener­gy-autonomous­ly. This effec­tive com­bi­na­tion of mechan­i­cal pro­tec­tion sys­tem and active elec­tron­ic sen­sor mon­i­tor­ing makes the sys­tem supe­ri­or to pure­ly elec­tron­ic col­li­sion avoid­ance sys­tems and effec­tive­ly pro­tects the shock-sen­si­tive com­po­nents of the motor spin­dle from the high force peaks of the col­li­sion. The result­ing kinet­ic ener­gy of the crash inter­cepts a built-in shock absorber. The dif­fer­ence is made by a dou­ble flange sys­tem with built-in per­ma­nent magnets.

They can guar­an­tee the required high hold­ing forces and rigid­i­ty. Dur­ing the dis­en­gag­ing process, com­pres­sion springs guide the motor spin­dle and then return it to its orig­i­nal posi­tion. The down­time is lim­it­ed to the exchange of tools, addi­tion­al exter­nal ser­vice is no longer need­ed. The sys­tem is ener­gy self-suf­fi­cient, main­te­nance-free and adapt­able to all com­mon motor spin­dle geometries.