Views: 89 Author: Site Editor Publish Time: 2019-06-25 Origin: Site
Denatured propeller blade will cause the outboard engine to vibrate, resulting in abrasion of the tail shaft and the tail bearing. Knowing the repair and maintenance of blade bending is extremely important. Here goes several correction methods for your information.
According to temperature, correction methods for blade bending include cold correction and hot correction. Cold correction means to do correction below heating temperature of 205 ° C. Cold correction applies to tips with blade tips and blade edges less than 30 mm thick. When the bending is small and the section is thin, it can adopt the hammer hitting load to correct, otherwise the static load to correct. Hot correction is mainly used for correction of big blade bending area. The temperature should refer to the preheating temperature of the weld repair. With the heating temperature, it should cover the entire section and be maintained until the correction is terminated.
According to specific correction tools, there are classified with press correction, plate correction, multi-plate correction, fixture correction.
Correct on a compression machine. Large and medium propeller blades can be deformed on the press of compression machine. Through a trolley lift the propeller and adjust the position with the crane.
Using platen correction on the plate. When correcting, the distance from the bolt to the point of application should be about 1/3 of the total length of the pressure plate. Slowly tighten the nut and apply pressure to the deformation of the blade through the plate, which gradually restore the original shape. It is also possible to change the jack at the place of the horn and correct it with a jack.
Multi-plate correction. Multi-plate correction is also called row correction. The two blades are used to correct the bending of the blade. It clamps the pressure plate on the curved blade and then corrects it with a jack. This platen method can only correct the bending deformation of the blade. It cannot be used to correct the distortion.
Correct with a clamp. For the deformation of the small propeller blades and the local deformation of the medium propeller blades, the fork-shaped pry bar can be used for correction.
There are many ways to correct the outboard engine propeller deformation. It should be selected according to different deformation conditions and equipment conditions, or several methods can be combined together.
After the correction and stress relief annealing, the blade bending should be carefully inspected. If necessary, coloring penetrant inspection can be used. Any cracks and unequal defects should be repaired. When the correction area is large, the pitch should be re-measured.
If the blade is severely bent or corrected in a large area, the stress reliving annealing should be adopted according to the material characteristics. For nickel-aluminum bronze paddles, the annealing requirements are generally reduced.