Abstract: A tube frame fixing structure comprises two cambered plates and tube frames. Each cambered plates has positioning holes without threads or a plurality of round grooves having threads on an inner wall thereof. Each tube frame has a plurality of through holes; the through holes of the tube frames, positioning holes and round grooves of the first and second cambered plate being aligned. A plurality of studs having threads are used to lock the two cambered plates and two tube frames. At first, each stud enters into one through hole of the tube frame. Then the stud enters into the round groove of one selected cambered plate of the two cambered plates to reach the positioning hole of the other cambered plate to resist against one wall of the tube frame. The stud moves forwards continuously so that the selected cambered plate will resist against the wall of the tube frame due to the interaction of the threads of the stud and round groove of the selected cambered plate.

Abstract: A joint structure, which allows a user to individually assemble and strengthens the stability of steel pipes. The joint structure mainly comprises of a fixture element, which can be slipped into a vertical steel pipe, a joint block, which connects two transversal steel pipes on the inner sides, and a fixture screw, which fastens a joint block and the vertical steel pipe to unite both of the transversal steel pipes and the vertical steel pipe. On the bottom of the vertical steel pipe and the fixture element, there are overlapped fixture screw holes. Both of the inner ends of the transversal steel pipes having clip holes. On the bottom of the extension panels located on the lateral sides of the joint block, there are inert blocks, which fit exactly with the clip holes. In the middle of the joint block, there is a piercing hole.

Abstract: The invention provides a kind of joint structure, which allows a user to individually assemble and strengthens the stability of steel pipes. The joint structure mainly comprises of a fixture element, which can can be slipped into a vertical steel pipe, a joint block, which cannects two transversal steel pipes on the inner sides, and a fixture screw, which fastens a joint block and the vertical steel pipe to unite both of the transversal steel pipes and the vertical steel pipe. On the bottom of the vertical steel pipe and the fixture element, there are overlapped fixture screw holes. Both of the inner ends of the transversal steel pipes equip clip holes. On the bottom of the extension panels located on the lateral sides of the joint block, there are inert blocks, which fit exactly with the clip holes. In the middle of the joint block, there is a piercing hole.

Abstract: A coupler structure for steel pipe conjoinment that provides for user DIY assembly having a coupling block overlapping inner sides of two horizontal sections of steel piping, a bolt inserted through the coupling block to fasten together the two horizontal sections of steel piping, a locating hole formed in the ends of each inner side of the two horizontal sections of steel piping, and a threaded hold tapped at a suitable position in the front corner of a straight section of steel pipe. A junction contact element extends from each of the two ends of the coupling block with insertion tabs fitted into the locating hole in each of the two horizontal sections of the steel piping. A semi-circular opening is formed at the mutually facing ends of the two horizontal sections of the steel piping such that after the semi-circular openings are brought together, their position is in a state of alignment with the threaded hole of the straight section of steel pipe.