《模具制造及模具表面采用激光技术增强使用寿命.doc》由会员分享，可在线阅读，更多相关《模具制造及模具表面采用激光技术增强使用寿命.doc（11页珍藏版）》请在三一文库上搜索。
1、模具制造及模具表面采用激光技术增强使用寿命Mold manufacturing and mold surface using laser technology to enhance service lifeLaser strengthening processing system for die surface and laser strengthening process, laser intensifying die listThe laser hardening technique is used to investigate the relationship between the h
2、ardening depth and wear resistance of the surface and the laser strengthening process parametersCan greatly improve the service life of die, laser transformation hardening (LTH), laser surface melting treatment (LSM), excitedOptical surface coating and alloying (LSC/LSA), laser surface chemical vapo
3、r deposition (LCVD), laser physics, gas phase depositionProducts (LPVD), laser shock (LSH) and laser amorphization, are used to improve die life by laser phase transition hardeningThe die life is improved by laser transformation hardening and laser cladding and alloying.Keywords die surface; laser t
4、ransformation hardening; strengthening; wear resistance;Since the scientific development of reform and opening up, Chinas mechanical engineering industry has developed rapidly, such as space, automobile manufacturing, etc.The requirements of precision, processing quality and service life of mould ar
5、e continuously improved in the field of dense instrumentHigher demands have been made. It is an important research topic to improve the precision, the processing quality and the service life of the die.The metal and nonmetal surface strengthening treatment used in industrial history is an important
6、way to improve the quality and service life of the dieThe utility model has the advantages of improving the comprehensive performance of the die, greatly reducing the cost, and giving full play to the potential of the traditional moldSignificance。 Commonly used mold surface strengthening treatment p
7、rocess has chemical heat treatment: carburizing, carbonitriding and so onDouble layer treatment: surfacing, thermal spraying, electrospark surface strengthening, PVD and CVD, etc.:Shot peening. The techniques used in history are more complicated, the processing cycle is longer, and the later deforma
8、tion is larger. recent yearsWith the emergence of high-power lasers and laser processing technology in industrial applications become increasingly widespread and mature,It provides a new technology for strengthening the surface of metal and nonmetal mold.1 laser strengthening treatment of die surfac
9、eThere are several common methods for laser hardening of die surface:Laser phase transformation hardening (LTH), laser surface melting treatment (LSM), laser surface coating and alloying(LSC/LSA) laser surface chemical vapor deposition (LCVD), laser physical vapor deposition (LPVD), and laser shock(
10、LSH) and laser amorphization, etc. The methods used to improve die life are laser transformation hardening and shockLaser surface cladding and alloying, usually provided high research and life of mold by laser transformation hardening technology and the principle ofTechnique.Laser phase transformati
11、on hardening (laser quenching) uses laser radiation to the metal surface so that its surface rises very highThe temperature and velocity rapidly reach the phase transition temperature to form austenite. When the laser beam leaves, the metal itself conducts heatThe occurrence of martensitic transform
12、ation on the metal surface is caused by self hardening. Compared with conventional quenching method, laser quenchingFire is in the hot and cold process, the high temperature gradient, resulting in a layer of surface hardnessSpecial quenching structures, such as grain refinement, high dislocation den
13、sity, etc. The hardness of the hardened layer is more rigid than that of ordinary hardeningIts still 15%. 20%. The depth of the hardened layer can reach 0. and 2. 5mm, which can greatly improve the wear resistance of the moldService life of long die.Composition of 2 laser phase transformation harden
14、ing (laser quenching) machining systemThe laser transformation hardening (laser quenching) strengthening system is a multi axis laser hardening systemIt consists of 3 parts: the first part is the laser system, which consists of laser head, excitation power supply, cooling system andThe resonant cavi
15、ty parameter conversion device is composed of second parts, a laser beam transmission and transformation device, wherein the laser beam is processed according to the requirementsSeek to guide the surface of the part to be processed, and simultaneously change the spatial intensity distribution of the
16、 laser beam to meet the requirements of the dieWith different surface, the stress is strengthened effectively. The light beam can be generated on the surface of the mold after being transformedThe required strengthening unit can control the 3D surface of the mould by multi axis linkage CNC systemTo
17、speed and effectively strengthen the processing; the third part is the computer numerical control system, the control laser work head and numerical control workThe multi beam motion of a laser beam determines the shape of the reinforcing band with respect to the trajectory of the laser beam relative
18、 to the workpieceLaser strengthening treatment of die surface.3 laser phase transformation hardening (laser quenching) strengthening treatment processMold, workpiece processing table, avoiding surface pretreatment coating: when the laser is determined, the metal material absorbs the laserAbility dep
19、ends mainly on its surface condition. The surface of metal material that needs laser treatment is processed mechanically,The surface roughness value is very small, and the reflectivity is up to 80% and 0%, so that most of the laser energy is reflected away. in order toTo improve the laser absorptivi
20、ty of metal surface, the surface of the material should be treated before laser heat treatmentThat is, blackening) on the metal surface to laser processing coated with a layer of laser has a high absorption capacitySurface pretreatment methods include phosphating, surface roughness, oxidation and sp
21、ray (brushing)Method, coating method and other methods, of which the most commonly used are phosphating and spray (brushing) coating method. Paint in common useAggregate has graphite, carbon black, manganese phosphate, zinc phosphate, water glass, etc., also has direct use of carbon ink and no light
22、Paint as a pretreatment coating. For some low carbon steel materials, they are treated with carbon black powder on their surfaceWhen laser quenching, it can play the role of carburizing. We use the blackening solution developed by Shanghai Institute of technology, processing methodSimple, can be spr
23、ayed directly on the surface of the mold workpiece, laser absorption rate of more than 90%.Optimization of process parameters for laser transformation hardening (laser quenching) hardening system: laser phase transformation hardening processParameters include laser output power P, spot size D and sc
24、anning speed V, in other conditions certain conditionsK, the depth of H laser hardening layer is related to P, D and V: H=P/ (D.v). In order to obtain the optimal processThe basic method is to determine a range of process parameters based on successful data, and then P, D, and V threeEach factor is
25、taken at 3 levels, and an orthogonal test table is made to carry out experimental research on the test piece. By laser phase transitionHardening experiments show that in general, the higher the laser power is, the deeper the hardening layer is, and the greater the scanning speed is, the hardened lay
26、er isShallower. When the laser power increases, the scanning speed increases and the spot diameter becomes smaller, the quenching layer is under the condition of technological parametersThe relationship between the hardness and the depth of the hardened layer is gradually increased.It can be seen th
27、at the surface of the material has been treated by laserThere is a marked increase in hardness.4 residual stress and wear resistance of mould hardened layerIn the process of laser hardening, the surface structure of metal material changes and the surface is relative to the materialThe generation and
28、 disappearance of the temperature difference will produce residual stress. The magnitude and distribution of residual stresses on the dieThe practical performance has a great influence on the distribution of residual stress produced by laser hardening along the hardened layer depth by laser workRate
29、 and the above process parameters determine the depth, range and area. Thus, the laser phase transformation is hardened in the die tableThe surface has a large residual compressive stress, which can effectively prevent fatigue cracks and improve the fatigue life of the die.The wear resistance of the
30、 mold surface and the microstructure, grain size, hardness and surface state of the mold materialAnd so on, and these factors are also affected by laser transformation hardening process parameters, so laser transformationThe technological parameters of the hardening system directly affect the wear r
31、esistance of the mold. Laser power and scanning speed versus dieThe effect of wear resistance of workpiece is remarkable. Thus, within a certain range, when the scanning speed is certain,Increasing power and abrasion resistance has increased. When the power is constant, the increase of scanning spee
32、d is also helpful to improve the wear resistance,Therefore, the laser strengthening technology can greatly improve the wear resistance of the material.The laser strengthening treatment of several different mould materials is carried out and checked with the actual working condition,The laser hardeni
33、ng technology can greatly improving the service life of the mold, and the hardening effect of cold die moreDistinct. The service life of the die obviously increased, and the practice increased from 25 thousand pieces of stamping to 100 thousand pieces, that is to say, the service life is improved3?
34、4 times. The advantage of laser strengthening technology is that it can be used according to the shape, characteristics and application requirements of the mouldWithin the specified area, no damage to the surface quality of the mold. The die with laser strengthening treatment can be directly put int
35、o workIt can reduce the cost of mould manufacturing, and use software to realize the automation and processing of laser intensification processing parametersThe process of simulation and real-time monitoring and processing, after the detection of surface texture and structure, to achieve complex sha
36、pes of moldIntelligent processing. An alloy obtained by cladding and alloying to obtain other components on the surface of a low-cost metal moldThe microstructure, the mechanical properties of the excellent mold, to improve the mold surface wear resistance, corrosion resistance and heat resistance.R
37、eference1 Li Ruxun, Ping Xueliang. Continuous laser hardening die blade machining process of J., 1995 (6).2 Chen, Xu Yourong. Die steel surface by laser cladding and modification of J. hardfacing alloy layer of metal heat treatment.Daniel, 1998 (1)3 Guan Guan. Handbook of laser processing technology M. Beijing: China Metrology press, 1998.4 Chen Guangnan. New technology and application of laser heat treatment J. metal heat treatment, 1998 (7)