Plasma torch and center pipe for plasma torch

A plasma torch comprising:

• an electrode including
• an internal passage that extends in an axial direction of the electrode,
• a tip portion that closes the internal passage,
• a convex portion including a root portion connected to an inner surface of the tip portion, the convex portion protruding from the inner surface of the tip portion, and
• an electrode insert at least partially arranged in the convex portion;
• a center pipe at least partially arranged in the internal passage of the electrode, the center pipe including
• a first pipe end that faces the inner surface of the tip portion in the axial direction, and
• a second pipe end located opposite to the first pipe end;
• and
• a coolant passage including
• a first passage arranged in the center pipe,
• a second passage arranged between an inner surface of the center pipe and the convex portion,
• a third passage arranged between the first pipe end and the inner surface of the tip portion, and
• a fourth passage arranged between an outer surface of the center pipe and an inner surface of the electrode
• a coolant flowing from the first passage through the second passage and the third passage to the fourth passage,
• at least a part of the convex portion being arranged in the center pipe,
• the inner surface of the center pipe including a first inclined surface having a diameter that decreases toward a distal direction, the distal direction being a direction extending from the second pipe end to the first pipe end,
• the first inclined surface extending toward the root portion of the convex portion, and
• the inner surface of the center pipe further including a second inclined surface extending along a direction opposite to the distal direction with respect to the first inclined surface, a diameter of the second inclined surface increasing toward the distal direction.