Abstract: A piston limiting structure, including: a cylinder, a piston, and a flange provided with a limiting piece, the cylinder has a piston hole perpendicular to an axial direction of the cylinder and penetrating through the cylinder, and a projection of the piston hole in a penetrating direction is circular. The piston is disposed in the piston hole in a form-fit manner and is slid in the piston hole in a reciprocating manner. A side wall of the piston is provided with a thrust groove, a bottom surface of the thrust groove forms a thrust surface on the side wall of the piston, and the thrust groove does not penetrate through two ends of the side wall of the piston along an axial length of the piston. The limiting piece abuts against the thrust surface.

Abstract: The present disclosure provides a pump body assembly, a heat exchange apparatus, a fluid machine and an operating method thereof. The pump body assembly includes a piston, a shaft, a piston sheath, and a cylinder. The shaft drives the piston to rotate and reciprocate within the piston sheath while rotating. The piston sheath is located in the cylinder, and a compression chamber is defined between an outer circumferential wall of the piston and an inner wall of the cylinder. A pressure relief recess is defined in the outer circumferential wall of the piston or the inner wall of the cylinder at a position corresponding to the compression chamber.

Abstract: A method for detecting a surface welding quality of friction stir welding includes: acquiring a continuous surface depth image of a welding seam; intercepting a surface depth image segment of the welding seam with a proper step size, and dividing the intercepted surface depth image segments of the welding seam into a front reference region, a thinned region and a rear reference region; judging whether flatness of the front reference region is less than a threshold, and if yes, taking a height of the front reference region at this point as a latest reference height; if no, judging whether the flatness of the rear reference region is less than the threshold, and if yes, taking a height of the rear reference region at this point as the latest reference height; if no, taking the reference height of previous depth image segment as the latest reference height; and calculating a difference.

Abstract: A method for detecting a surface welding quality of friction stir welding includes: acquiring a continuous surface depth image of a welding seam; intercepting a surface depth image segment of the welding seam with a proper step size, and dividing the intercepted surface depth image segments of the welding seam into a front reference region, a thinned region and a rear reference region; judging whether flatness of the front reference region is less than a threshold, and if yes, taking a height of the front reference region at this point as a latest reference height; if no, judging whether the flatness of the rear reference region is less than the threshold, and if yes, taking a height of the rear reference region at this point as the latest reference height; if no, taking the reference height of previous depth image segment as the latest reference height; and calculating a difference.

Abstract: A water damping device includes a steel frame and a water-blocking cup; the device is immersed in the water and connected under the main bridge girder by wire ropes. One end of the water-blocking cup is provided with a blocking ring and a cover. The water-blocking cup cover is mounted between the cup and the blocking ring and is movably connected to the water-blocking cup. The blocking ring is used to prevent the water-blocking cup cover from opening towards the outside of the cup; an array of water-blocking cups is mounted on the steel frame along the downward direction of the water-blocking cup cover.

Abstract: A water damping device includes a steel frame and a water-blocking cup; the device is immersed in the water and connected under the main bridge girder by wire ropes. One end of the water-blocking cup is provided with a blocking ring and a cover. The water-blocking cup cover is mounted between the cup and the blocking ring and is movably connected to the water-blocking cup. The blocking ring is used to prevent the water-blocking cup cover from opening towards the outside of the cup; an array of water-blocking cups is mounted on the steel frame along the downward direction of the water-blocking cup cover.