External opening aligning machine for pipelines

The invention belongs to the technical field of pipeline welding and discloses an external opening aligning machine for pipelines. The external opening aligning machine for the pipelines comprises a fixed clamping assembly, a movable clamping assembly, a guide rod and a horizontally-moving hydraulic cylinder. The guide rod is arranged between the fixed clamping assembly and the movable clamping assembly. The horizontally-moving hydraulic cylinder is connected with the fixed clamping assembly and the movable clamping assembly. The fixed clamping assembly comprises a first upper frame and a first lower swing arm. The first lower swing arm is hinged to the first upper frame through a hinge shaft. The movable clamping assembly comprises a second upper frame and a second lower swing arm. The second lower swing arm is hinged to the second upper frame through a hinge shaft. During opening aligning operation, the main pipeline abuts against the inner side of the first upper frame, and the first lower swing arm tightl