Vision-based detection of weld pool width in TIG welding of copper-clad aluminum cable

In order to realize automatic control of the width of weld pool, a visual sensor system for the width of weld pool detection is developed. By initiative arc light, the image of copper plate weld pool is taken back of the torch through the process of weakening and filtering arc light. In order to decrease the time of processing video signals, analog circuit is applied in the processing where video signals is magnified, trimmed and processed into binary on the datum of dynamic average value, therefore the waveform of video signals of weld pool is obtained. The method that is used for detecting the width of weld pool is established. Results show that the vision sensing method for real-time detecting weld pool width to copper-clad aluminum wire TIG welding is feasible. The response cycle of this system is no more than 50 ms, and the testing precision is less than 0. 1 mm.

Orthogonal tests of copper-clad aluminum bimetal continuous casting by nitrogen pressure core-illing

To provide theoretical basis and practical guidance for preparing composite rods by direct continuous casting, copper-clad aluminum composite rods of external copper layer diameter 12 mm and inner aluminum core diameter 8 mm were manufactured. Orthogonal tests consisted of three factors and three levels were carried out to research the effects of melting copper temperature, continuous casting speed and nitrogen pressure on the performance of composite rods. Results showed that nitrogen pressure is the most important factor in influencing the surface quality; continuous casting speed is the most important factor in influencing copper & aluminum inter diffusion amount. Nitrogen pressure can noticeably improve the surface quality and make the rods easily be drawn out, but the surface quality does not show visible improvement when the nitrogen pressure is above 0.05 MPa. Measured by tests, the compound layer can be divided into three types according to its cladding layer degree: deficient cladding, normal cladding and excess cladding. The diameter of normal copper-clad aluminum composite rods can be successfully drawn less than 0.6 mm without annealing.

Effect of continuous induction annealing on the microstructure and mechanical properties of copper-clad aluminum flat bars

Copper-clad aluminum （CCA） flat bars produced by the continuous casting-rolling process were subjected to continuous induction heating annealing （CIHA）, and the effects of induction heating temperature and holding time on the microstructure, interface, and mechanical properties of the fiat bars were investigated. The results showed that complete recrystallization of the copper sheath occurred under CIHA at 460℃ for 5 s, 480℃ for 3 s, or 500℃ for 1 s and that the average grain size in the copper sheath was approximately 10.0 μm. In the case of specimens subjected to CIHA at 460-500℃ for longer than 1 s, complete recrystallization occurred in the aluminum core. In the case of CIHA at 460-500℃ for 1-5 s, a continuous interracial layer with a thickness of 2.5-5.5 μm formed and the thickness mainly increased with increasing annealing temperature. After CIHA, the interracial layer consisted primarily of a Cu9A14 layer and a CuA12 layer; the average interface shear strength of the CCA flat bars treated by CIHA at 460-500℃ for 1-5 s was 45-52 MPa. After full softening annealing, the hardness values of the copper sheath and the aluminum core were HV 65 and HV 24, respectively, and the hardness along the cross section of the CCA flat bar was uniform.

短路激烈程度对铜包铝导线熔珠引燃能力及组织特征的影响

调查铜包铝导线短路故障引发的火灾,需在起火点处找到迸溅熔珠,通过熔珠的特征确认其来源于短路点,再根据可燃物情况推算其引燃能力。用电焊机模拟短路故障,调节输出电流,改变短路电弧激烈程度;根据东北地区房屋特点,选取碎木屑为被引燃物,在50A、150 A、200 A、250 A、300 A电流下重复试验20次,统计试验的熔珠数量、引燃、形状和组织等特征。结果表明：电流越大,试验的电弧越剧烈,熔珠数量越多,大粒径熔珠比例越高,所有熔珠粒径满足d≤5. 5 mm;随电流增大,熔珠携带的能量升高,可引燃碎木屑的最小熔珠粒径d减小,而d 〈1. 26 mm时,一定不会引燃碎木屑,而d〉 1. 5mm时,则多数情况下均可引燃碎木屑;铜的存在使迸溅熔珠更易形成树枝晶,小孔洞分散组织中,随电流的升高和熔珠体积的增大,枝晶臂更加粗大,小气孔逐渐汇集成大孔洞。

Microstructures and mechanical properties of Cu/Al compound materials during thermal cycle

Cu/Al compound materials,named as copperclad aluminum bus bars,are widely used in heat dissipation of modern engineering.The thermal cycle tests were conducted at 200,250 and 300℃for different cycle times,respectively.Effects of thermal cycle temperatures and thermal cycle times on micro structures and mechanical properties of the interface were studied.The results show that the width of bonding layer and bond strength are significantly affected by thermal cycle temperatures and times.Nonetheless,the variety or the quantity of intermediate compounds is scarcely influenced.Al_(2)Cu,Cu_(9) Al_(4)and CuAl were identified on the interface.With the increase in cycle times,grains of the material grew up.However,grains of the interface grew up more apparently than those of Cu and Al.The knowledge may be applied in the establishment of service condition and quality evaluation of material.