The invention discloses a jet propulsion pipeline polishing equipment, which includes a polishing block. The polishing block is provided with a rotating cavity. The rotating cavity is provided with a polishing mechanism. The polishing mechanism includes a hollow shaft. The left side of the polishing mechanism A turning mechanism is provided. The turning mechanism includes a rack. A transmission cavity is provided in the polishing block. The rack is provided with an upper end wall that can move up and down. The upper side of the turning mechanism is provided with a water supply mechanism. The water supply mechanism includes a push plate, and a polishing cavity is provided in the polishing block. When the device is used to polish the pipeline, the device can be moved to facilitate the polishing of the pipeline, and the device can automatically add fresh water during polishing without manual labor Price adjustment improves polishing efficiency and reduces operation complexity.

The present invention relates to an actively dampened centerless grinding process for a centerless grinding machine having wheels, between which there is arranged a part to be ground, and heads carrying the wheels, which process has moving the wheels closer to one another by applying pressure on the part for the grinding thereof, such that vibrations are generated in the grinding machine due to grinding, measuring the vibrations due to grinding, and introducing, depending on the measurement, an active damping force (F.sub.act) parallel to the force flow of the grinding machine and by means of using an inertial actuator acting directly on one of the heads, such that the vibrations due to grinding are attenuated.

A rack bar includes a shaft member having a toothed section. The toothed section has a plurality of rack teeth, and extends over a portion of an entire length of the shaft member along a longitudinal direction of the shaft member. The shaft member has a grinding-finished outer peripheral surface extending over the entire length of the shaft member including the toothed section. A method for manufacturing the rack bar includes forming the toothed section by plastic working and grinding the outer peripheral surface to improve shape accuracy.

A rack bar includes a shaft member having a toothed section. The toothed section has a plurality of rack teeth, and extends over a portion of an entire length of the shaft member along a longitudinal direction of the shaft member. The shaft member has a grinding-finished outer peripheral surface extending over the entire length of the shaft member including the toothed section. A method for manufacturing the rack bar includes forming the toothed section by plastic working and grinding the outer peripheral surface to improve shape accuracy.

The present invention relates to a torsional severe plastic deformation method for a metal bar to which surface polishing is applied to the metal bar to improve the mechanical properties of the metal bar. According to an embodiment of the present invention, there is provided a torsional severe plastic deformation method for a metal bar, which includes: applying torsion to a metal bar; and removing a surface defect on the surface of the metal bar, the surface defect being caused by the applying of torsion, wherein the removing of the surface defect is carried out in a continuous manner in which the removing of the surface defect is performed together with the applying of torsion or in a discontinuous manner in which the applying of torsion is temporarily stopped and then the applying of torsion is performed, and the removing of a surface defect increases the amount of torsional rotation or the shear strain applied to the metal bar.

A cylindrical protective device is disclosed for the polished rod and packing of an oil well pumping system. The protective device is constructed with abrasive sandstone material, wraps around the polished rod, and is positioned on top of, or anchored to, the packing. The device has two symmetrical parts, each part having semicircular structure, the parts when joined together form a circular cavity to accommodate the polished rod therethrough. As the polished rod undergoes cyclic motion driven by a horsehead, the device smooths rough edges and oil chips, extending the polished rod's lifespan. By reducing friction and minimizing wear on the packing, the device prevents oil and natural gas leaks during the pumping process. Using the protective device, pump systems can operate more efficiently, ensuring a smoother and safer oil extraction process.

A cylindrical protective device is disclosed for the polished rod and packing of an oil well pumping system. The protective device is constructed with abrasive sandstone material, wraps around the polished rod, and is positioned on top of, or anchored to, the packing. The device has two symmetrical parts, each part having semicircular structure, the parts when joined together form a circular cavity to accommodate the polished rod therethrough. As the polished rod undergoes cyclic motion driven by a horsehead, the device smooths rough edges and oil chips, extending the polished rod's lifespan. By reducing friction and minimizing wear on the packing, the device prevents oil and natural gas leaks during the pumping process. Using the protective device, pump systems can operate more efficiently, ensuring a smoother and safer oil extraction process.

A stent includes a high radial force segment and a highly flexible segment, where the diameters of the high radial force segment and the highly flexible segment are different. For example, the stent may be formed from a tube having varying diameters as it extends distally combined with increased strut density to achieve increased flexibility distally while reducing loss of radial stiffness. The stent may further be placed with an additional stent segment, where the additional stent segment has a radial force similar to the radial force of the highly flexible force segment.

A stent includes a high radial force segment and a highly flexible segment, where the diameters of the high radial force segment and the highly flexible segment are different. For example, the stent may be formed from a tube having varying diameters as it extends distally combined with increased strut density to achieve increased flexibility distally while reducing loss of radial stiffness. The stent may further be placed with an additional stent segment, where the additional stent segment has a radial force similar to the radial force of the highly flexible force segment.

A manufacturing apparatus for producing a curved contour on an end face of a roll includes a grinding device and a holding device, linearly movable relative to the grinding device. The grinding device is for grinding the curved contour on the end face. The holding device is for holding the roll between the holding device and the grinding device. A method for producing the curved contour on the end face using the manufacturing apparatus is also disclosed. The method includes driving the holding device to move in a linear fashion relative to the grinding device.