Gun Drill

A gun drill cutter head, comprising:

• a main head body having a distal end face;
• at least one coolant delivery port formed in the distal end face;
• at least one coolant supply path communicating with the at least one coolant delivery port;
• a main discharge port formed in the distal end face;
• at least one cutting chip discharge groove communicating with the main discharge port, the cutting chip discharge groove extending in a lengthwise direction along an outer face of the gun drill cutter head;
• and
• a seal portion extending continuously over an entire circumference of a portion of the main head body;
• wherein:
• the seal portion bridges over the cutting chip discharge groove;
• and
• the cutting chip discharge groove extends on both sides of the seal portion.

A gun drill comprising:

• a gun drill cutter head installed on a distal end portion of a tool shank, the gun drill cutter head comprising:
• a main head body having a distal end face;
• at least one coolant delivery port formed in the distal end face;
• at least one coolant supply path communicating with the at least one coolant delivery port;
• a main discharge port formed in the distal end face;
• at least one cutting chip discharge groove communicating with the main discharge port, the cutting chip discharge groove extending in a lengthwise direction along an outer face of the gun drill cutter head;
• and
• a seal portion extending continuously over an entire circumference of a portion of the main head body;
• wherein:
• the seal portion bridges over the cutting chip discharge groove;
• and
• the cutting chip discharge groove extends on both sides of the seal portion.