Laser aggrandizement technology improves mould service life

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Summary: The laser aggrandizement that introduced to be used at mould surface processes system and laser aggrandizement technique, the relation between the sclerotic layer deepness that discussed surface of laser aggrandizement mould and wear-resisting function and parameter of laser aggrandizement craft, use laser aggrandizement technology to be able to improve the service life of the mould substantially. Keyword: Stimulate smooth aggrandizement; Mould; Wear away / the life swift and violent development as industry of our country car, home appliance, raised taller requirement to mould industry. How to improve the treatment quality of the mould and service life, it is the task that people explores ceaselessly all the time. Using exterior aggrandizement to handle is the important way that improves mould quality and service life, the its integral performance to improving a mould, latent capacity that reduces mould of tradition of cost, sufficient play substantially, have very important sense. Technology of commonly used processing of mould surface aggrandizement has thermo-chemical treatment (like nitrogen of cementite, carbon in all ooze) , exterior answer layer is handled (wait like aggrandizement of surface of v, thermal spraying, electric spark, PVD and CVD) , exterior treatment aggrandizement is handled (the) such as the bolus that be like gush. These methods are old much technology is relatively sophisticated, processing is periodic and longer, the presence after processing is larger be out of shape. In recent years, the application that goes up in industry as the occurrence of high-power laser and technology of laser beam machining is extensive with each passing day, mature, the aggrandizement that is mould surface offerred a kind of new technique approach. The method that laser of processing technique of aggrandizement of 1 laser surface uses at finishing is much, include among them: Laser photograph becomes sclerotic (LTH) , laser surface is fused handle (LSM) , fu of laser surface besmear and alloy are changed (LSC/LSA) , laser become apparent learns gas phase deposit (LCVD) , deposit of laser physics gas phase (LPVD) , laser is pounded (LSH) and laser blame brilliant are changed etc, the method that already was used at improving mould life by research among them has laser photograph to change sclerosis and Fu of laser surface frit and alloy are changed, the article basically discusses use laser photograph to harden the mechanism that changes a technology to improve mould life and method. Laser photograph becomes sclerotic (laser quenchs) it is to use laser irradiation to arrive metallic surface, make its surface with very tall warm up speed is achieved quickly change temperature and form austenite, after stimulating beam of light to leave, use metallic itself to heat is conducted and happen " quench oneself " , make metallic surface produces martensite change. Quench with the tradition methodological photograph is compared, laser quenchs undertake in urgent heat, urgent cold procedure, temperature gradient is tall, formed a hardness in the surface thereby extremely tall special quench organization, if grain is refined, exalted wrong density. Its quench the hardness of the layer is compared common quenched hardness is tall still 15% ～ 20% . Deepness of hard layer of temper by dipping in water can be amounted to 0.

1 ～ 2.

5mm, can raise the wearability of the mould greatly consequently, prolong the service life of the mould. The composition of system of treatment of 2 laser aggrandizement pursues the 1 laser aggrandizement that has much axis linkage for machines sketch map of systematic work principle. It divides composition by 3: The first part is laser system, by harmony of laser head, incentive power source, cooling system brace up composition of device of antrum parameter shift; The 2nd part is transmitted for beam of light with shift device, stimulate beam of light to ask to guide by treatment treat surface of processing spare parts, enter the commutation that the intensity between line space distributings to stimulating beam of light at the same time, undertake effective aggrandizement is handled in order to satisfy different to mould surface position getting power. Beam of light can produce needs aggrandizement unit in mould surface after classics commutation, the numerical control system that adopts much axis linkage can undertake can accusing to the three-dimensional curved surface of the mould, handle with effective aggrandizement quickly; The 3rd part is system of computerized numerical control, the much axis such as head of control laser job and numerical control workbench moves, the belt that its stimulated photograph of beam of light to decide aggrandizement to the athletic contrail of workpiece appearance, in order to realize the laser aggrandizement processing of mixed pattern surface. Graph the composition of system of treatment of 1 laser aggrandizement 3 laser aggrandizement handles technology 3.

Coating of pretreatment of 1 workpiece surface decides when laser hind, the metallic stuff absorption to laser ability basically depends on its surface condition. The metallic stuff surface that needs laser processing commonly passes machining, exterior surface roughness is worth very small, its reflectivity can amount to 80% ～ 90% , make major laser energy is reflexed. To raise a metal the watch faces the absorptivity of laser, finishing should undertake to material surface before laser heat treatment (often say black change processing) , the metallic appearance that handles in need laser namely has the painting that absorbs ability higher on besmear one layer to laser. The method of exterior pretreatment includes phosphor to change a way, raise exterior surface roughness law, oxidation law, gush (brush) a variety of methods such as painting magic art, plated film law, among them relatively commonly used is phosphor spends law and in season (brush) painting magic art. Commonly used coating aggregate has zinc of manganese of black lead, carbon black, phosphoric acid, phosphoric acid, water glass to wait. Also have use carbolic element directly prepared Chinese ink and the lacquer that do not have light regards pretreatment as coating. To material of some mild steel, in its the surface is handled with carbon black powder, cementite effect can have when undertaking laser quenchs. The Hei Huarong liquid that we use place of Shanghai smooth machine to develop (86-1) , its processing technique is simple, but direct gush is brushed in workpiece surface, laser absorptivity amounts to 90% above. 3.

2 craft parameter optimizes laser photograph to become sclerotic craft parameter basically has laser to output power P, facula size D reachs scanning speed V, in other condition certain condition falls, the deepness H of laser sclerosis layer and P, D, V is like next relations: H=P/(D. V) . To get best craft parameter, basic method is the data according to already having a success, define scope of parameter of a craft, again with P, D, v3 factor, each take 3 levels, make orthogonal experiment watch undertake experimenting study on test specimen. Graph the 2 material Cr-Mo that pull late pattern place to use for car taillight bracket are cast-iron, below different scanning speed, the relation curve with laser power and sclerotic deep layer. Graph 3 fall for different laser power, the relation curve of scanning speed and sclerotic layer. Graphic representation makes clear: Be in usually, laser power is higher, sclerotic layer is deeper; Scanning rate is older, sclerotic layer is more shallow. Graph 4 to be in laser power P=1200W, scanning speed V=15mm/s, facula diameter D=4.

Below the craft parameter condition of 5mm, quench the hardness of the layer and sclerotic layer are deep the relation between. Can see from which, the hardness of surface of the material after classics laser is handled has relatively remarkable rise. Pursue speed of 2 laser power, scanning and curve of sclerotic layer relation 1 -- 6mm/s 2 -- 15mm/s 3 -- 25mm/s graph scans below power of 3 different laser speed and curve of sclerotic layer relation 1 -- 600W 2 -- 1000W 3 -- 1500W pursues layer of sclerosis of 4 hardness edge is deep distributing 4 sclerotic layer remains stress and wear-resisting, the change of structure of organization of metallic stuff appearance and surface are opposite at material interior the generation of difference in temperature is mixed disappear, be sure to produce leftover stress. The size of leftover stress and distributinging state has very big effect to the economic performance of the mould, if the distributinging situation with the hard difficult layer of temper by dipping in water of leftover stress edge that laser sclerosis produces pursues 5. By the graph 5 visible, laser photograph becomes sclerotic to produce bigger remains to press stress in mould surface, prevent the generation of fatigue crackle effectively, improve the fatigue life of the mould. Graph a variety of elements such as condition of discretion of size of the microstructure of the wear-resisting function of surface of late distributinging pattern and material, grain, hardness, surface concern layer of sclerosis of edge of 5 leftover stress, and the effect that these elements suffer processing technology parameter again, consequently the craft parameter of laser aggrandizement affects the wear-resisting performance of the mould directly. Graph 6 with the graph 7 be opposite for laser power and scanning speed the influence of function of 35CrMn steel wear-resisting. See by the graph, inside certain limits, when scanning rate is fixed, raise power wearability to increase somewhat; When power is certain, of scanning speed rise to also conduce to raise wearability. Graph 8 handle for laser of 42CrMo material classics (P=1200W, v=55mm/s, d=3.

Between 5mm) hind and groovy processing wear away comparative, use laser aggrandizement technology to be able to improve the wear-resisting performance of material greatly it is thus clear that. Graph the influence of 6 laser power (V=20mm/s) pursues the influence of 7 scanning speed (P=1800W) pursues 8 wearability are comparative 5 conclusion carry the laser that to a few kinds different mould material undertakes aggrandizement processing, undertake checking contrast with real work circumstance, make clear the service life that uses laser aggrandizement technology to be able to raise a pattern substantially, and the aggrandizement effect of cold die is more apparent. If be opposite,the sunken model that the drift that T8A steeliness builds and Cr12Mo steeliness build undertakes laser sclerosis is handled, laser sclerosis layer is 0.

15mm, hardness is 1200HV, service life increases apparently, by punch 2.

50 thousand raise 100 thousand, namely life raises 3 ～ 4 times. Use laser aggrandizement technology, its advantage depends on: (1) can be in according to the appearance characteristic of the mould, use requirement appoint undertake inside area, and do not have any injury to exterior quality. Via the mould after laser is handled, do not need follow-up treatment to be able to throw production to use directly, reduced the production cost of the mould thereby. (2) passes aggrandizement of laser of work out appropriative to handle software, the computer that can realize laser to handle craft parameter is optimized automatically, the computer of structure of organization of the appearance after the computer that handles a process emulates imitate and real time monitoring and laser processing and function is forecasted, realize the finishing that the complex form of the mould and artificial intelligence change. (3) uses laser frit Fu and alloy to change wait for a technology, can be in cheap the alloy that metallic stuff surface layer gets aleatoric part and corresponding microcosmic organization, acquire good integrated and mechanical property thereby, improvement and the wear-resisting that improve material appearance, be able to bear or endure corrode and heat-resisting function. These technologies are used at discarding as useless the rehabilitate of the mould and aggrandizement, have relatively wide market perspective. CNC Milling