Spindle and cutting apparatus including the same

A spindle comprising:

• a housing;
• a bearing housed in the housing;
• a main shaft rotatably supported by the bearing, the main shaft being provided with a through hole passing through the main shaft in an axial direction of the main shaft, the main shaft including a first end located on a first side in the axial direction and a second end located on a second side in the axial direction;
• a collet chuck extending into the through hole and being movable in the axial direction, the collet chuck including a first collet end located adjacent to the first end of the main shaft and a second collet end located on the second side in the axial direction, the first collet end of the collet chuck being able to grip a machining tool to machine a workpiece;
• a draw bar extending into the through hole and being movable in the axial direction, the draw bar including a first bar end located adjacent to the first end of the main shaft and a second bar end located adjacent to the second end of the main shaft, the first bar end of the draw bar being connected to the second collet end of the collet chuck;
• a first securer secured to the main shaft and holding the bearing from below;
• and
• a second securer secured to the housing, holding the bearing from below, and located outward of a spindle radial direction of the first securer, wherein
• the housing includes:
• an air inlet which is located above the bearing and through which air is introduced into the housing;
• an air passage located below the bearing such that the air introduced into the housing through the air inlet is capable of flowing below the bearing;
• and
• an air outlet which is located below the bearing and through which the air flowing below the bearing is capable of being discharged out of the housing;
• the second securer includes:
• a first securer portion that presses against the bearing from below and that includes a recess recessed downward from an upper surface of the first securer portion;
• and
• a second securer portion that is secured to the housing;
• the air passage includes:
• a first air passage portion located below the bearing;
• and
• a second air passage portion located laterally of the first securer;
• the air outlet is located below the second air passage portion;
• the air flowing through the first air passage portion passes along a surface of the bearing;
• the first air passage portion is defined by the bearing and the recess in the first securer portion of the second securer;
• the second air passage portion is defined by the first securer and the second securer;
• and
• the air flowing through the air passage passes through the first air passage portion and simultaneously passes along the surface of the bearing.