Multipolar single-head plug and method for manufacturing same

A method for manufacturing a multipolar single-head plug, the multipolar single-head plug comprising:

• a bar electrode exposed at a tip thereof;
• multiple tubular electrodes concentrically arranged on an outer circumference of the bar electrode and exposed at the outer circumference on a side closer to a root than the exposed part of the bar electrode at the tip;
• and
• an insulator composed of an insulating part between the bar electrode and the tubular electrode and an insulating part between the tubular electrodes,
• the multipolar single-head plug being integrated with an insulating resin for insert molding that forms part of the insulator,
• the method comprising:
• a first step of providing an insulating material so as to cover at least a given area of the outer circumference of the bar electrode or a given area of an outer circumference of one of the tubular electrodes, the insulating material being provided to a middle section of at least one of the insulating parts composed of a front section, the middle section, and a rear section, the middle section being separate from the front and rear sections, the insulating material being separate from the insulating resin for insert molding;
• a second step of placing the bar electrode and the multiple tubular electrodes in a mold;
• and
• a third step of forming the insulator including an insulating part with the insulating resin tightly contacting the separate insulating material by pouring the insulating resin into the mold, thereby integrating the bar electrode, the multiple tubular electrodes, and the insulator.