RU1803841C - Method of detection of flaws in metal articles with machining of their surfaces - Google Patents

Abstract

Usage: quality control of products in mechanical engineering. SUMMARY OF THE INVENTION: the surface of a product is heated by a laser beam with a power density of 108-109 W / m2, moving at a speed of (5-25) -. 1 s.p. f-ly.

Description

The invention relates to flaw detection and can be used to detect surface and subsurface defects, e.g., pores, cracks, hairs, sinks, non-penetration, etc.

The purpose of the invention is the detection of subsurface defects while improving product quality.

The goal is achieved in that in the method of defectoscopy of metal products during their surface treatment, which consists in heating the surface of the products with a high-energy heat source and visually inspecting it (the surface is heated by a laser beam moving along it with a power density selected from the condition that the defective sections of the product are melted, In this case, heating is carried out by a laser beam with a power density of 25)

108-109 W / cm2 with speed (.

The method is as follows

In the initial position, the actuators rotate (or move) the product and move the laser beam. Further

supply laser radiation to the workpiece. During laser processing of the product, the surface of the product is heated to 1000-1200 ° С with rapid cooling due to heat removal into the product volume and obtaining a structure of increased hardness (55-65 LDCs) of the martensitic type. In this case, the intensity in the zone of defects (cracks, pores) sharply decreases heat sink, the surface overheats with the opening of the defect. The sharp edges of the defects are melted and they are cleaned of contaminants. A visual assessment of the surface makes it possible to assess its condition and conclude that the product is suitable and then used.

In the absence of defects in the surface layers of the product, quenching occurs with an increase in operational characteristics while maintaining the surface cleanliness not worse than grade 8.

Carrying out laser processing with a laser beam with a power density of 10 -109 W / cm and a speed of (5-25) m / s avoids the fusion of the surface of the product, which improves the quality of the product, and eliminate

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processing without hardening and revealing subsurface defects.

Example, The quality of the surfacing of the necks of the crankshaft of the ZMZ-53 engine was controlled by the wire NpZOKhGSA while thermally hardening the surfaces of the necks. Before laser thermal hardening (after grinding), visual inspection made it possible to establish a number of defects on the surfaces of the first three root necks. In accordance with the requirements for the acceptance of the shaft from repair, the surface quality is satisfactory, and the shaft can be directed to the assembly of the engine in this condition.

After laser heat treatment, the number of opened defects has increased significantly.

In accordance with the requirements for accepting a shaft from restoration according to the number and size of pores, such a shaft cannot be received for assembling the engine and must be rejected.

Laser processing of the crankshaft was carried out according to the following modes: radiation power of 780 W, diameter of the focused beam 3 mm, linear velocity of the beam relative to the treated surface 25 mm / s. For heat treatment and, accordingly, defect detection, a CU2 cw laser of the LGN-702 type with a nominal power of up to 800 W was used.

Thus, heat treatment by a moving focused laser beam made it possible to simultaneously detect defects in the metal of a part with a high degree of probability of such detection. In this case, an increase in the energy density in the focused beam makes it possible to increase the number of detected defects, which, in this case, include cleaned surface defects and opened ones (due to the melting of thin

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walls) subsurface defects (pores, shells) located at a depth of 0.1-0.6 mm. So, in the above example, with a decrease in the speed of beam movement by 2 times, the number of detected defects (pores and shells) was: on the first neck 14; on the second 12; on the third 14.

When processing the shift program for the ZMZ-53 engine shafts, it was found that existing control methods let 40% of the weld necks with shells pass through, which are rejected by laser heat treatment.

Measurements show

5 that the proposed method for detecting defects allows the rejection of very critical parts with a low quality of their manufacture, even when the part was considered suitable before laser processing. With insignificant application of a heat beam, the real dimensions of the defect in are significantly larger than those observed or recorded by known methods.

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Claims (2)

1. The method of defectoscopy of metal products during their surface treatment, which consists in heating the surface of the products with a high-energy heat source and visually inspecting it, characterized in that, in order to detect subsurface defects while improving the quality of the products, the surface is heated by a laser moving along it beam power density selected from the condition of the melting of the defective sections of the product. 2. The method according to claim 1, on the basis of which the heating is carried out with a laser beam raft 8. 9 g power rating 10-10 W / m / s soon style (5-25).