Swivel chair provided with length-adjustable leg tubes

A swivel chair provided with length-adjustable leg tubes, comprising:

• a chair frame assembly, a seat leg connection assembly, and a leg tube assembly rotatably connected with the chair frame assembly through the seat leg connection assembly, wherein the chair frame assembly includes a chair cloth, two turning bases, two turning base reinforcing pieces, a back tube, a seat frame and an upper connection plate, the back tube is perpendicular to the seat frame, a left end and a right end of the back tube can be turned forwards by 90° respectively through the two turning bases so as to be hinged to the seat frame, the upper connection plate is fixedly mounted at a bottom of the seat frame, the two turning base reinforcing pieces are respectively attached to outer sides of the two turning bases and are connected with the back tube and the seat frame through rivets, together with the turning bases, and the back tube and the seat frame are sleeved with the chair cloth;
• the leg tube assembly includes a bushing used for mounting the seat leg connection assembly, an upper leg tube fixing base, four upper leg tube connectors, two upper stretchable leg tubes, two lock mechanism, two lower leg tubes, four universal leg pads, four tie rods, a tie rod base, a tie rod base fixing tube and two upper necking leg tubes, wherein an annular flange is arranged at an upper end of the bushing and has an outer diameter greater than an inner diameter of the upper leg tube fixing base, the bushing is inlaid in the tie rod base fixing tube from top to bottom and is integrally connected with the tie rod base fixing tube, the tie rod base fixing tube is disposed in the upper leg tube fixing base and is able to move upwards or downwards, and a lower end of the tie rod base fixing tube is fixedly mounted on an upper portion of the tie rod base;
• the two upper stretchable leg tube are arranged adjacently, the two upper necking leg tubes are arranged adjacently, the two upper stretchable leg tubes are bilaterally symmetrical with the two upper necking leg tubes, lower ends of the upper necking leg tubes are necking ends, upper ends of the two upper stretchable leg tubes and upper ends of the two upper necking leg tubes are respectively arranged in the four upper leg tube connectors in a sleeved manner and are rotatably connected to the upper leg tube fixing base through rivets, the necking ends of the two upper necking leg tubes are respectively connected with two said universal leg pads, lower ends of the two lower leg tubes are connected with the other two universal leg pads, upper ends of the two lower leg tubes stretch into lower ends of the two upper stretchable leg tubes and stretch upwards or retract downwards through the two lock mechanisms, the four tie rods each having one end hinged to a lower portion of the tie rod base and one ends respectively hinged to upper portions of the two upper stretchable leg tubes and upper portions of the two upper necking leg tubes;
• the back tube can be turned forwards through the turning bases so as to be folded, the two upper stretchable leg tubes and the two upper necking leg tubes can be drawn inwards, and the lower leg tubes can stretch upwards or retract downwards in the upper stretchable leg tubes by locking or unlocking the lock mechanisms.