Dispersion-strengthened copper electrode for upset weldingThe present invention relates to resistance welding electrode, a kind of dispersion-strengthened copper electrode for upset welding material is provided especially.
The resistance welding electrode head is a kind of conductive material of high flow rate, is widely used in the welding process of body of a motor car.It should have good electrical conductivity and high softening temperature.The alloy of elements such as copper that the electrode tip great majority employing melting of present most of factories practical application is produced and chromium, zirconium, nickel.These alloy raw materials cost an arm and a leg; and its adopts is that the principle of alloy strengthening makes material obtain high rigidity under the room temperature, and under higher temperature, its invigoration effect fades away; the softening temperature of material is only about 450 ℃; so head very fast distortion under the high temperature action that welding produces makes head can not keep the type shape that designs, thereby influences welding quality when using; the life-span of this soldering tip is shorter; about about 20,000 times,, can not overcome this shortcoming fully though adopting the water-cooled protection.Also there is in the recent period the technology that adopts internal oxidation to make oxide dispersion intensifying copper product electrogenesis in next life welding resistance electrode tip to come out.This material softening temperature improves greatly than melting material, thus service life significant prolongation, but its manufacturing process complexity is difficult for large-scale industrial production.It also has the shortcoming of dispersoid particle skewness in addition, thereby the welding head quality instability of producing.
The object of the present invention is to provide a kind of conductance height, the softening temperature height, material is even, is easy to big industrial resistance welding electrode.
The invention provides a kind of dispersion-strengthened copper electrode for upset welding head, make by powder metallurgy method, it is characterized in that used powder: (1) selects granularity for use is the pure copper powder of 5～100 μ m, and ceramic powder such as metal oxide or the carbide of granularity between 0.5～2 μ m made raw material, the amount of ceramic powders is 0.5～3wt%:(2) with raw meal mechanical ball milling alloying, ratio of grinding media to material is 1: 3～10, and the ball mill revolution is 500～800n/min, and the time 2～20 is little right.The present invention comes down to adopt the method for high-energy ball milling, and the pure copper powder of anticipating and pure ceramic powder are carried out ball milling with dry method or wet method.The principle that pottery is selected is the hardness height, and at high temperature chemical property is stable, not with matrix copper generation chemical reaction.Ceramic powder content is between 0.5～3wt%, if content is lower than 0.5wt%, then strengthening effect is not obvious, if content surpasses 3%, then can reduce the electric conductivity of material, and material is become fragile.Mixed powder behind ball milling vapour pressure in cold stamping die is become green compact, and vapour pressure pressure is at 3～7 tons/centimetre2Between.The vapour pressure green compact are squeezed into bar through hot extrusion technique, and extrusion temperature is between 750 ℃～850 ℃.With this material forge hot or be machined into the spot-wedling electrode head.The kind electrode material has the conductance height, the softening temperature height, and advantage such as elevated temperature strength is good, the electrode life of manufacturing is long, and the spot-welded on quality is good.The present invention has not only reduced the consumption of precious materials such as copper, chromium, nickel, and is easy to control product quality in large-scale industrial production.Below by embodiment in detail the present invention is described in detail.
Embodiment
To granularity is that 10～50 μ m copper powders were handled 4 hours with hydrogen reducing, and treated copper powder and pure zirconia aluminium powder (granularity 0.7～1 μ m) are carried out premixed, carries out ball milling then 10 hours, alumina content is 0.5%, 1%, 1.5%, 2.0% and 2.5%, totally five groups.Powder after grinding is cold-pressed into garden cylindricality green compact in cold stamping die, the pressure of colding pressing is 6 tons/centimetre2, Cylinder diameter 7cm, high about 15cm carries out copper-clad to the Cylinder surface and handles, and carries out hot extrusion then, and extrusion temperature is 820 ℃, the diameter of rod 10mm that is squeezed into.The conductance of made material is more than 75% of fine copper, and softening temperature is 800 ℃.Five groups of materials all are processed into the spot-wedling electrode head,, wherein can finish solder joint 3.5 ten thousand times for one of longest-lived group in the enterprising spot welding experiment of industrial production line.