The article presents the review of the main methods of restoration and repair of machine parts: mechanical and bench work, welding, surfacing, metal coating, chrome plating, nickel plating, steeling (iron plating), bonding, hardening the surface of parts and restoring their shape under pressure. The areas of application of each method, its advantages and disadvantages are noted. Welding and surfacing are used to restore more than half of all repaired car parts. With the help of welding, cracks and fractures on the frame and platform are repaired, patches, various overlays and reinforcing gussets are put, and the crankcases of the units are restored. Damaged or worn threads on stub axles and other parts are restored by welding, followed by cutting a new thread. The internal threads are restored in the same way. Restoration of parts by surfacing consists in surfacing the worn working surfaces in such a way that they can be processed to the nominal or repair dimensions. When repairing cars, automatic and semi-automatic surfacing and welding under a layer of flux or in a carbon dioxide environment are used. Damaged and worn parts can be repaired by pressure. This method is based on the use of the ductility of metals. The parts are restored to their nominal dimensions with the help of special devices, by moving a part of the metal from non-working areas of the part to its worn surfaces. When restoring parts by pressure, not only their external shape changes, but also the structure and mechanical properties of the metal. Plastics are used to restore worn parts when repairing metal-cutting machines. As an adhesive, plastics are widely used for bonding broken parts, as well as for obtaining a fixed connection of parts made of metallic and non-metallic materials. When repairing metal-cutting machines, the most widely used plastics are textolite, wood laminated plastics and fast-hardening plastic — styracryl.
Lasers are widely used and have wide prospects in the most various branches of mechanical engineering. The paper considers the possibilities of using changes in laser technologies in billet production, welding and Assembly various materials, engraving and painting.
The article considers the shock-intermittent processing method, which is used for cutting blind threads M12x1.5 in nuts made of steel grade X18N9T. Compared to the conventional method, it allows increasing the processing productivity; the durability of the thread taps has increased to 300 holes (with manual thread cutting, the durability of the taps is 100 holes). The method allows mechanizing labor-intensive threading operations. The optimal conditions of processing by this method are determined based on ensuring sufficient strength of the cutting wedge of the tool under repeated loading and, at the same time, creating the most intense impact on the material of the cut layer of the workpiece. The destruction of the processed material on impact most easily occurs at critical deformation rates, which, for instance, equal 60 m/s for corrosion-resistant steel. This leads to an overestimation of the impact pulse values, and consequently, chipping of the cutting edges of the tool. Therefore, for these processing conditions, there is an optimal value of the pulse load transmitted by the spindle to the tool. For threads M10 and M12 with pitches of 1.25 and 1.5 in parts made of steel grades X18N10T, the best results are achieved at loads corresponding to the increment of the dynamic moment of the driven bushing with the tool. At high pulse loads, the durability of the working tool is sharply reduced, and at lower loads, the cutting performance is reduced. One of the positive features of shock-intermittent cutting is the presence of breaks that facilitate the operation of the cutting wedge due to the better penetration of the coolant. Therefore, shockintermittent cutting is carried out at more intensive modes than conventional continuous cutting. However, the tool life does not decrease as a result, but even increases. The relative length of the cutting area, determined by the angle, should be chosen based on the fact that the temperature in the cutting area does not have time to reach its steady value, equal to the cutting temperature during the normal long-duration cutting, carried out continuously.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.