Background technology
In industrial production, near the quality of laser cutting, but cost is far below laser cutting aspect the cutting surface quality of material for meticulous plasma cutting technique.Therefore, in recent years, the quantity of digital controlling plasma cutting equipment gathers way very fast in each enterprise.Yet the at present main dependence on import of efficient numerically controlled plasma cutting machines must be bought as annex simultaneously as the crucial consumable accessory electrode of equipment, and it is expensive.And electrode is as the main consumables in the plasma cutting operation, and the length in its service life directly has influence on processing cost and the production efficiency of plasma cutting, and electrode is changed more frequent, and its processing cost is more high, and production efficiency is corresponding just more low.
External plasma cutting electrode is cooperated with the axis body mechanical compaction by copper sheathing seat, silver-colored body and hafnium filament core three and forms, and when heavy current is passed through, has two bed boundary contact resistances and gap thermal resistance, makes radiating effect and conductive effect not good enough.Chinese patent ZL03150716.6 discloses a kind of employing vacuum brazing method oxygen-free copper block set, silver-colored body, hafnium filament has been connected, by brazing member being assembled (as adopting positioning fixture control postweld interval), being placed thread and foil-shaped brazing material, and control soldering processes, the electrode surface quality that obtains is good, non-oxidation, coloured light is bright, the welding even compact, and steady quality, product percent of pass reach more than 98%; Operating mode is used and is shown, the electrode that obtains reaches 500 meters for the cutting ship plate single-piece life-span, than exceed 200 meters of inlet electrode.But, not only there is the expensive problem of pure white silver-colored coolant jacket of use in this technology, and when welding needs itself and copper sheathing seat and hafnium filament are coupled together respectively, also need adopt paper tinsel shape and thread solder during connection, in addition, also need formulate special positioning fixture the joint clearance of brazing is positioned, have complex operation, the defective of plasma cutting electrode assembling unit structure complexity.
Summary of the invention
At existing in prior technology the problems referred to above and defective; the purpose of this invention is to provide that a kind of cost is low, simple to operate, quality is good, be fit to the vacuum brazing method of the plasma cutting electrode of large-scale production, to satisfy the market demand of plasma cutting electrode.
For achieving the above object, the technical solution used in the present invention is as follows:
A kind of vacuum brazing method of plasma cutting electrode, comprise: assemble plasma cutting electrode sub-assembly, assembly is put into vacuum drying oven, vacuumizes, is heated to brazing temperature, soldering step by step, is cooled off, comes out of the stove, it is characterized in that: described assembling plasma cutting electrode sub-assembly refers to put into solder wire and hafnium filament in the copper sheathing seat from bottom to top successively, then the copper sheathing seat is just put, be placed on the bottom in the anchor clamps of horizontal plane.
As preferred version, the fit-up gap of copper sheathing seat and hafnium filament is 0.02~0.05mm.
As preferred version, the diameter of described solder wire and hafnium filament diameter are equal to.
As preferred version, the draw ratio of described solder wire is 0.6~0.8.
As preferred version, described solder wire is silver-bearing copper eutectic solder silk.
As preferred version, being evacuated to vacuum is 1.0 * 10
-2~8 * 10
-3Pa.
As preferred version, described substep is heated to brazing temperature and refers to: be heated to 400~500 ℃ with 15~25 ℃/min earlier, insulation 10~30min; Be heated to 700~770 ℃ with 5~15 ℃/min then, insulation 40~80min; Be heated to brazing temperature with 15~25 ℃/min again.
As preferred version, described brazing temperature is 810~850 ℃.
As preferred version, described soldering refers at brazing temperature insulation 15~40min.
As preferred version, described cooling refers to cool off with stove.
Compared with prior art, beneficial effect of the present invention has been to simplify the vacuum brazing technique of plasma cutting electrode, adopt vacuum brazing method directly copper sheathing seat and hafnium filament to be carried out soldering, make the electrode that obtains not only simple in structure, cost is low, and surface quality is good, the even weld densification, and the resistivity that adopts electric-resistivity method to record electrode has only (0.03~0.04) * 10
-6Ω m.
The specific embodiment
The present invention will be further described in detail below in conjunction with drawings and Examples.
The vacuum brazing method of a kind of plasma cutting electrode provided by the invention, comprise: assemble plasma cutting electrode sub-assembly, assembly is put into vacuum drying oven, vacuumizes, is heated to brazing temperature, soldering step by step, is cooled off, comes out of the stove, it is characterized in that: described assembling plasma cutting electrode sub-assembly refers to solder wire 2 and hafnium filament 3 are put into 1 li of copper sheathing seat from bottom to top successively, then copper sheathing seat 1 is just being put, be placed on the bottom in the anchor clamps 4 of horizontal plane (as shown in Figure 1).
Described anchor clamps 4 are made up of upper plate 41, lower plate 42 and four support bars 43, and upper plate 41 is provided with fixing hole 44 and several locating holes 45 of 4 fixed support bars 43, the upper surface of described lower plate 42 is the plane, the external diameter of the internal diameter of described locating hole 45 and copper sheathing seat 1 is complementary (as shown in Figures 2 and 3), places a plasma cutting electrode sub-assembly that assembles in each locating hole.
Because of the fit-up gap of copper sheathing seat and hafnium filament size influence solder the capillary joint filling and and the interaction degree of solder and mother metal, thereby influence compactness and the performance of soldering; The joint clearance of brazing is excessive, and capillarity weakens even disappears, and solder is difficult to fill up the gap; The joint clearance of brazing is too little, hinders solder and fills, and is difficult to form the high joint of ratio of brazing area; Therefore, the fit-up gap of preferably copper block set of the present invention and hafnium filament is 0.02~0.05mm.
Because what of shape, size and the solder amount of solder have certain influence to brazing quality, and the plasma electric pole piece is columned, therefore, the present invention selects brazing wire, diameter and the hafnium filament diameter of preferred solder wire are equal to, and assembling is simple like this, and the solder amount is controlled easily.In addition, the draw ratio of the preferred solder wire of the present invention is 0.6~0.8, and can satisfy solder fills up whole joint clearance of brazing to this solder amount on the one hand, can prevent that on the other hand the solder amount from too much flowing out brazed seam and polluting surface of the work and cause waste etc.
Because the fusing point of silver-bearing copper eutectic solder is moderate, good manufacturability, and have good electrical conductivity, thermal conductivity, intensity and toughness, and therefore, the preferred silver-bearing copper eutectic solder of the present invention silk.
Influence the wetting of solder and brazing member surface state because the vacuum degree is too low, and the too high volatilization that can accelerate metallic element of vacuum, therefore, the preferred vacuum of the present invention is 1.0 * 10
-2~8 * 10
-3Pa.
As preferred version, the present invention carries out the process that substep is heated to brazing temperature and is: be heated to 400~500 ℃ with 15~25 ℃/min earlier, and insulation 10~30min, purpose is impurity and the gas of extracting out in the stove, reduces generation of defects; Be heated to 700~770 ℃ with 5~15 ℃/min then, insulation 40~80min, mainly be to make the temperature of test specimen even this moment; Be heated to brazing temperature with 15~25 ℃/min at last.
The inventor also discovers: brazing temperature is too low or temperature retention time is too short, can cause the solder fusing insufficient, form the cavity in the joint easily, and brazing temperature be too high or the long meeting of temperature retention time causes the more frangible compounds of generation in the joint, even crackle appears, influence the performance of joint.Therefore, brazing temperature of the present invention is preferably 810~850 ℃, at brazing temperature insulation 15~40min, cools off with stove then.
Embodiment 1
According to Fig. 1, earlier oxygen-free copper block set 1, silver-bearing copper eutectic solder silk 2 (diameter is 2.5mm, highly is 1.6mm), hafnium filament 3 are pressed the fit-up gap assembling of 0.03mm, then the oxygen-free copper block set is just put, be placed on the bottom in the anchor clamps 4 of horizontal plane.
Assembly is put into vacuum drying oven, be evacuated to 8 * 10
-3Pa.
Earlier be heated to 400 ℃ with 20 ℃/min, insulation 20min; Be heated to 750 ℃ with 10 ℃/min again, insulation 60min; Be heated to 840 ℃ with 20 ℃/min again, insulation 20min.
Come out of the stove with the stove cooling, it is full namely to obtain joint filling, and solder does not have the cross flow phenomenon, joint flawless, and the moderate plasma cutting electrode of compound layer thickness, and described plasma cutting electrode only is made up of copper sheathing seat and hafnium filament.
The resistivity that adopts electric-resistivity method to record the electrode that obtains is 0.04 * 10
-6Ω m.
Embodiment 2
According to Fig. 1, earlier oxygen-free copper block set 1, silver-bearing copper eutectic solder silk 2 (diameter is 2.5mm, highly is 1.8mm), hafnium filament 3 are pressed the fit-up gap assembling of 0.05mm, then the oxygen-free copper block set is just put, be placed on the bottom in the anchor clamps 4 of horizontal plane.
Assembly is put into vacuum drying oven, be evacuated to 1 * 10
-2Pa.
Earlier be heated to 400 ℃ with 20 ℃/min, insulation 20min; Be heated to 750 ℃ with 10 ℃/min again, insulation 60min; Be heated to 820 ℃ with 20 ℃/min again, insulation 40min.
Come out of the stove with the stove cooling, it is full namely to obtain joint filling, and solder does not have the cross flow phenomenon, joint flawless, and the moderate plasma cutting electrode of compound layer thickness, and described plasma cutting electrode only is made up of copper sheathing seat and hafnium filament.
The resistivity that adopts electric-resistivity method to record the electrode that obtains is 0.03 * 10
-6Ω m.
In sum, the vacuum brazing technique of plasma cutting electrode of the present invention is simple, and the electrode that obtains is not only simple in structure, and cost is low, and surface quality is good, the even weld densification, and the resistivity that adopts electric-resistivity method to record electrode has only (0.03~0.04) * 10
-6Ω m.
Should be noted that at last: above embodiment only is used for the present invention is further specified; can not be interpreted as limiting the scope of the invention, some nonessential improvement that those skilled in the art's foregoing according to the present invention is made and adjustment all belong to protection scope of the present invention.