The basic forms of manual welding positioner are extensor type, tilting rotary type and double column single rotary type.

(1) The main feature of this welding positioner is that the motor-driven working device at one end of the column runs in one direction of rotation and the other end follows the active end. Both sides of the column can be designed as lifting type to meet the welding requirements of structural parts of different specifications. The disadvantage of this type of welding positioner is that it can only rotate in a circumferential direction, so it is necessary to pay attention to the suitability of the welding seam.

(2) Double-seat head-tail double-rotary head-tail double-rotary welding positioner is to add a rotational degree of freedom on the basis of double-column single-rotary welding positioner. This type of welding positioner is advanced, has large welding space, and can rotate the workpiece to the desired position. It has been successfully applied in many construction machinery manufacturers.

(3) The working device of the L-shaped double-rotary welding positioner is L-shaped, with two degrees of freedom of rotation in two directions, and can rotate at any direction (+360 degrees). The welding positioner has the advantages of good openness and easy operation.

(4) The C-type double-rotary C-type double-rotary welding positioner is the same as the L-type double-rotary welding positioner, but the fixture of the welding positioner is changed slightly according to the shape of the structural parts. This type of welding positioner is suitable for the welding of structural parts such as buckets of loaders and excavators.

The selection principle of welding positioner has the following three points: one is the principle of workpiece application, the other is the principle of convenient welding, and the third is the principle of easy operation.

(1) The applicable principle of workpiece is that the shapes of different structural parts of construction machinery vary greatly, and the requirements of welding time-varying displacement are also different. Therefore, the suitable welding positioner should be selected according to the structural characteristics and welding requirements of the welded structural parts.

(2) According to the principle of convenient welding, according to the condition of manual welding operation, the selected welding positioner should be able to transfer any weld of the welded workpiece to the position of flat welding or ship welding, so as to avoid vertical welding and uphill welding and ensure the welding quality.

(3) The principle of easy operation should be to select safe and reliable welding positioner with good openness, low operation height and compact structure, so as to facilitate workers'operation and placement of welding positioner. If the welding operation height of the positioner for welding structural parts is high, the worker can weld by the way of pad height, or adjust the height position by equipping the hydraulic lifting platform.