A VERY EXPERIENCED PIPER CHEYENNE SINGLE PLT EXPERIENCED A NOSE GEAR FAILURE DURING LNDG ROLLOUT AT ZZZ.

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FLT ORIGINATED IN ZZZ1 AND WAS FLOWN IFR TO ZZZ TO PICK UP ACFT OWNERS. EVERYTHING WAS NORMAL. ALL SYS CHKED NORMAL ON THE PREFLT; THROUGH PREDEP AND WERE OPERATING NORMALLY DURING THE FLT. UPON ARRIVING IN ZZZ; I WAS CLRED FOR A VISUAL APCH TO RWY 9L. AT APPROX 5 NM FROM THE RWY THRESHOLD; AFTER THE PROPS WERE ADVANCED AND APCH FLAPS WERE SELECTED; THE GEAR WAS LOWERED. 3 GREEN LIGHTS WERE OBSERVED AS WAS THE GEAR HANDLE RETURNING TO THE NEUTRAL POS. THE ACFT WAS SLOWED TO BLUE LINE; 3/4 DEG FLAPS SELECTED; THEN FULL FLAPS AT 500 FT. WINDS WERE APPROX 070 DEGS AT 18 KTS AND TOUCHDOWN ON THE CTRLINE IN A SLIGHT SLIP. LOWERING THE NOSE TO THE RWY SMOOTHLY; WHILE COMING INTO REVERSE; THERE WAS A SLIGHT BUMP THEN THE NOSE GEAR COLLAPSED. NO GEAR WARNING HORN SOUNDED AND THE ACFT SLID TO A STOP ON THE CTRLINE. AFTER PROP IMPACT; CONDITION LEVERS WERE MOVED TO THE CUT-OFF POS; FUEL PUMPS TURNED OFF; MASTER SWITCH TURNED OFF; AND FUEL SHUT OFF. THERE WERE NO PAX ON BOARD AND I EVACED THE ACFT ON THE RWY. I ATTRIBUTED MY FORMAL TRAINING IN EMER PROCS TO PREVENTING ANY ADDITIONAL DAMAGE TO THE ACFT AND MY SUCCESSFUL AND ORDERLY EVAC. AT THIS TIME; THE CAUSE OF THE NOSE GEAR FOLDING IS UNKNOWN.