Fitting tube structure of glue gun

A fitting tube structure of a glue gun comprising:

• a conical connection part, an accommodation chamber formed in a bottom of the conical connection part and configured to accommodate a heater, a feeding segment formed on a front end of the conical connection part, and an open segment defined on a rear end of the conical connection part and configured to connect with a fitting assembly;
• wherein the fitting assembly includes a first fixing tube, an O ring, a second fixing tube made of aluminum or aluminum alloy, a stop sleeve, a locating ring, and a coupling tube;
• wherein a first end of the first fixing tube is connected with the open segment of the conical connection part, and a second end of the first fixing tube is coupled with the second fixing tube, wherein the first fixing tube has a stepped portion formed on a center thereof;
• wherein the O ring is retained between the stepped portion of the second fixing tube and the second fixing tube;
• wherein the stop sleeve is fitted on an outer wall of the first fixing tube and has a large-diameter extension and a small-diameter extension, and the large-diameter extension covers the first fixing tube, and the locating ring is fitted on an outer wall of the large-diameter extension;
• wherein the coupling tube is fixed on an outer wall of the small-diameter extension;
• and
• wherein the first fixing tube, the second fixing tube, and the stop sleeve are fitted and are fixed by the locating ring and the coupling tube.