The large heterogeneous board such as blame nods solder craft imitate

Energy-saving environmental protection already became a society to produce one of themes of the life. Because resistor spot welding is efficient, energy-saving, realize the characteristic such as mechanization, automation easily, the main welder that remains automobile body up to now art. As the occurrence of new product, form of connect of resistor spot welding to get used to the need of new product, and no longer bureau be confined to is akin wait for thick material. The connect of thick heterogeneous material such as blame applies extensively also. As a result of board large presence difference, and ability of the electric conduction of material, heat conduction is different, formation frit nucleus is as not symmetrical as joint face, produce deflection, make laminose penetration rate insufficient, affect the effective carrying capacity that solder nods. Undertake study to the spot welding craft of this kinds of connect, seek parameter of spot welding craft and the concern that solder orders quality, have certain real sense. The occurrence of composite material automobile body, it is car light quantified efficient way. With thick for 1.

4mmQ235 armor plate and 0.

The DP590 of 8mm is light the connect that quantifies board composition is research target, use ANSYS software, use finite yuan of analytic method, acquire the concern of craft parameter and spot welding quality, get reducing frit nucleus deflection, assure the way of the carrying capacity of contact. The geometry of appearance of form of 1 frit nucleus describes the geometrical parameter that describes appearance of frit nucleus form to have: Frit nucleus diameter, frit appears deflection of nucleus of height of nucleus of rate, frit, frit to wait for a few kinds. Change to state appearance of frit nucleus form, diameter of the nucleus that use frit undertakes stating to frit nucleus figuration. Namely frit nucleus size is larger, the carrying capacity of contact is stronger, lose more conversely [1] . Solder the main factor that electric current, weld time is dimension of decision frit nucleus and frit nucleus deflection, the electrode pressure factor that attributes opposite secondary [2] . Contact structure sees a picture 1. D is frit for frit nucleus diameter, H and H deep. 2 finite of yuan of model building spot welding is axial symmetry finite yuan of model. Unit type chooses PLANE67 of pyroelectricity coupling unit, this unit has voltage and temperature two freedom are spent, coupling of pyroelectricity of spot welding of OK and successful implementation is analysed. Reseau differentiates the principle that follow is: In osculatory area, temperature field and electric field variation are complex and rapid, reseau wants fractionize, to improve computational efficiency, other area reseau needs thick delimit. The processing of attrib border condition and wait thick board spot welding connect is similar, relevant data parameter can consult document is obtained [3-4] . Finite yuan of model and attrib border condition are like a graph respectively 2 (A) , (B) place is shown. Spot welding border heats up action form is convection heat exchange and radiation heat exchange. Attrib border ③ is the action of electrode and cooling water, the consideration is compulsive convection heat exchange, coefficient of convection heat exchange is 3800W/ (M2 · ℃ ) . Attrib border ④ is the surface of electrode and air action, put in action of convection, radiate, its heat up commutative result to express with W of α of coefficient of integrated heat exchange. Voltage of coupling of attrib border ① , ② falls on, ensure electric current can guide. 3 imitate result and the computational condition of discussion article are: F=3500N, weld time T=0.

25s, solder electric current is 6kA respectively, 6.

6kA, 7.

5kA, if the imitate result of its temperature field pursues 3 (A) , (B) , (C) be shown. Nextpage can see, as the accretion of load electric current, temperature of frit nucleus area lifts gradually, radius is ordinal increase. Different board thick, heat conducts coefficient, electrical conductivity different also, heat up namely conduct ability to differ. According to joule's law Q=I2Rt, material contacts resistor to differ, produce quantity of heat to differ. So frit nucleus shows asymmetry distributinging pattern along joint face. Balance phasor according to Fe-Fe3C, steely kind of material temperature prep above 1450 ℃ , can regard frit nucleus as the area, if pursue medium,gules area place is shown. The area of 750 ℃ is temperature prep above hot influence area. The quantity of heat that computation of a few groups of parameter gives above can satisfy craft to ask, but do not come off to assure frit nucleus, spot welding has a the smallest critical diameter. According to experience, blame thick board when the butt joint, of craft parameter custom-built it is reference with thin plate. According to experimental formula Dmin=5 δ [3] (δ is board thick) computation, the smallest frit nucleus diameter that the article assures to frit nucleus does not rupture is 4.

47mm. From the graph 4 (A) , (B) , (C) can see, the frit nucleus diameter that obtains below 3 kinds of parameter is D =4 respectively.

24mm, D=4.

8mm, D=5.

4mm. Reach quite, divide I=6kA to cannot satisfy a requirement, other two groups of parameter are feasible. From the graph 3 be pleasant to the eye piece, 7.

The configuration of nucleus of frit of load electric current of 5kA is close friends at 6.

6kA, the impact that to prove to solder electric current, weld time and frit nucleus deflection measure, the article made imitate calculation further. 4 test and verify reduce method of frit nucleus deflection to compare I=6.

6kA, t=0.

25s, I=10kA, t=0.

The frit nucleus deflection of 2s is measured, it is a basis with the distance of joint face and line of frit nucleus center. If pursue,5 are shown. From the graph 5 in can see apparently, (B) face of joint of workpiece of distance of line of center of group frit nucleus should is bordering on (A) group, namely (B) the quantity of frit nucleus deflection of the group is less than apparently (A) group. 5 last words 5.

When 1 weld time is changeless, frit nucleus diameter increases as the addition of load electric current, want melting point of electrode temperature short of only can. 5.

2 be aimed at problem of frit nucleus deflection, the article wins the following verdict: Use tough standard, use big load electricity namely, short weld time, can reduce frit nucleus deflection. The account in this conclusion and book is same, show article simulative rationality. 5.

The parameter of spot welding craft of the 3 connect that article place narrates: Can consider T=0.

25s, I=6.

6kA, with T=0.

25s, I=7.

5kA these two groups, but the issue that considers frit nucleus deflection, the proposal uses I=10kA, T=0.

2s this group, because this group of parameter are calculated,gotten frit nucleus diameter and laminose electrode temperature satisfy a requirement, and amount of frit nucleus deflection is very small. CNC Milling