Welded light-weight long-life arc striking electrode and welding method

Abstract

The invention provides a welding type light-weight long-service-life arc striking electrode and a welding method. The welding type light-weight long-service-life arc striking electrode comprises an anode head, a cathode head, an anode column and a cathode column. The anode head and the cathode head are made of single or composite metal conductor materials resistant to arc ablation; and the anode column and the cathode column are made of single or composite metal conductor materials. According to a current path, the arc starter is connected to the two ends of a rail in a bore opening area of the high-speed electromagnetic propulsion device and powered by an external power source, current conducts the rail and an armature path of the high-speed electromagnetic propulsion device, and an armature slides in a bore in an accelerated mode from a bore tail to a bore opening under the action of electromagnetic force; meanwhile, the metal or plasma medium in the bypass electrode gap of the arc striking device induces the gap to disrupt and discharge, and the arc striking effect is achieved. The cable can meet the requirements of conductivity, high tensile strength and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high-speed electromagnetic propulsion, and particularly relates to a welded lightweight long-life arc striking electrode and a welding method, which can conduct a current level of hundreds of kiloamperes or above. BACKGROUND

[0002] A conventional arc striking device adopts a form of bore parallel connection of a large resistance to achieve the purpose of reducing arc current by forming a loop of system current through the large resistance after the armature is discharged from the bore. Such parallel arc striking structure always participates in system energy loss and reduces system efficiency in the process of electromagnetic propulsion. The bore arc striking device independently developed by the Institute of Electrical Engineering of the Chinese Academy of Sciences adopts a loop parallel open gap electrode. When the armature moves in the bore, it does not participate in system energy consumption. When the armature is discharged from the bore, the bore voltage jumps, and when it exceeds the breakdown voltage threshold, the bore burns, the high-speed moving arc makes the gap between the electrodes of the arc striking device break down and discharge, which not only plays an arc striking role and reduces the influence of bore burning on the flight attitude of the armature discharged from the bore, but also effectively protects the bore material.

[0003] As shown in Figure 1 The independently developed bore arc striking device includes a flow guide anode 1a, a flow guide cathode 1b, a bypass anode 2a, a bypass cathode 2b, a fastener 3a, and an insulating spacer 4a. The flow guide anode 1a and the flow guide cathode 1b are made of single or composite metal good conductor material and have a left-right symmetrical structure. The bypass anode 2a and the bypass cathode 2b include an anode column, an anode head, a cathode column, and a cathode head, and are made of single or composite metal good conductor material. The fastener 3a can be a standard bolt and nut, or can be designed into a non-standard part according to the geometric size of the arc striking device or connected to the armature / ballast of the electromagnetic rail launcher by a resin-based insulating fiber winding fastener device. It is powered by an external power supply, and the current conducts the rail and armature path of the electromagnetic propulsion device. The armature is accelerated and slides in the bore from the bore tail to the bore mouth under the electromagnetic force. When the armature is discharged from the bore, the gap between the bypass electrodes of the metal dielectric or plasma induced arc striking device breaks down and discharges, realizing the arc striking effect.

[0004] Because the deflection of the muzzle of the high-speed electromagnetic propulsion device needs to be reduced, the lightweight requirement is needed; the muzzle is impacted by the shock wave and the transient electromagnetic force, the strength requirement is needed; the muzzle area is ablated by the high-temperature fluid and the plasma, the temperature resistance requirement is needed; the joule heat generated by the hundreds of kiloampere to the megampere current is consumed through the electric arc, the conductivity requirement is also needed. Therefore, the electrode material of the arc igniter needs to be lightweight, high strength and resistant to high-temperature electric arc ablation. At present, the integrated electrode cannot meet the above requirements at the same time, so the single metal or metal alloy material with high melting point and high strength is selected for the electrode head part of the electrode which contacts the high-temperature electric arc, and the single metal or metal alloy material with high strength and lightweight is selected for the electrode column part. And the electrode head and the electrode column need to realize reliable electrical connection. The ordinary non-welding process such as bolt pressure connection form increases the volume and weight, and cannot realize the complete connection of the contact surface; the fiber winding form is also not suitable for the structure; the conventional lap welding is limited by the welding depth, and cannot realize the complete welding of the large-size contact surface. SUMMARY

[0005] To solve the above technical problems, the application provides a welded lightweight long-life arc ignition electrode and a welding method. The arc ignition electrode is a key flow guide component of the muzzle arc igniter of the high-speed electromagnetic propulsion device, which is composed of at least four left-right and upper-lower symmetrical electrodes, each electrode including an electrode head and a bypass electrode column. In order to ensure the connection strength of the corresponding electrode head and electrode column and the complete conduction of the pulse large current in the electrode, the corresponding electrode head and electrode column are connected by the rotary friction welding process, which makes the welding surface of the electrode head and the electrode column completely welded. The rotary friction welding generates heat by the relative rotation and friction of the electrode head and the electrode column, so that the contact surface reaches the plastic state and then the pressure is applied to realize the solid-state connection, which can meet the requirements of conductivity, high tensile strength and the like.

[0006] To achieve the above purpose, the application adopts the following technical solutions:

[0007] The application discloses a welded light-weight long-life arc striking electrode, which comprises an anode head, a cathode head, an anode column and a cathode column; the material of the metal electrode head is single or composite metal good conductor material resistant to arc ablation, the cross section of the welding position of the electrode column is circular or circular ring structure, and the structure shape of the remaining part can be designed according to actual application; the arc current between the armature and the track is guided, and long life is realized. The material of the metal electrode column is single or composite metal good conductor material, the cross section of the welding position of the electrode head is circular or circular ring structure, and the structure shape of the remaining part can be designed according to actual application; the residual current fed into the arc eliminator by the power supply is conducted, and light weight is realized. The current path is as follows: the arc striking device is connected to the tracks at both ends of the muzzle area of the high-speed electromagnetic propulsion device, and is powered by an external power supply; the current conducts the track and the armature path of the high-speed electromagnetic propulsion device; the armature is accelerated to slide in the muzzle from the muzzle tail to the muzzle mouth under the electromagnetic force; when the armature exits the muzzle, the metal or plasma medium in the electrode gap bypasses the arc striking device, the gap breakdown discharge is induced, and the arc striking effect is realized.

[0008] Further, the rotary friction welding is continuous rotary friction welding, and the welding interface is free of holes and cracks, and forms full-section sealed connection.

[0009] Further, the material of the anode head and the cathode head is tungsten-copper alloy, and the material of the anode column and the cathode column is copper alloy or brass.

[0010] Further, the outer diameter of the anode column and the cathode column is equal to or slightly smaller than the outer diameter of the corresponding anode head and cathode head, forming a coaxial cylindrical structure.

[0011] Further, the thickness of the anode head and the cathode head and the thickness of the anode column and the cathode column are determined according to different calibers and weight requirements.

[0012] Further, the post-weld coaxiality of the anode head and the anode column and the cathode head and the cathode column is not greater than 0.1 mm.

[0013] Further, the electrode gap length is indirectly calculated according to the caliber and the residual current, and is not greater than the caliber of the electromagnetic propulsion device; and the electrode outer diameter is calculated according to the electromagnetic force.

[0014] The application further provides a welding method of the welded light-weight long-life arc striking electrode.

[0015] Step 1. cleaning the electrode head and the electrode column;

[0016] Step 2. placing the electrode head and the electrode column in the welding equipment and positioning;

[0017] Step 3. starting the rotary friction welding equipment, rotating the electrode column and keeping the electrode head static.

[0018] Step 4. Continue to apply axial pressure, so that the electrode head, electrode column is in close contact, and plastic deformation occurs, forming a weld;

[0019] Step 6. After the welding is completed, the weld is cooled and solidified;

[0020] Step 7. After the welding is completed, the size of the weld that exceeds the original outer diameter is polished and cleaned to ensure that the surface size is qualified.

[0021] Further, in step 1, acetone is used for cleaning.

[0022] Further, in step 3, the rotation speed of the electrode column is set to 3000 r / min, and the axial pressure is 100 MPa; in step 4, the axial pressure is continued to be applied to 200 MPa.

[0023] Beneficial effects:

[0024] 1. Synergistic effect: Rotational friction welding through solid-state metallurgical bonding (non-melting welding) avoids defects caused by melting point differences, realizes atomic-level sealed connection of high-density electrode head (tungsten copper) and lightweight electrode column (beryllium copper or chromium copper and other copper alloys), and meets the requirements of lightweight and long service life.

[0025] 2. In terms of characteristic dimensions, a synergistic structure is constructed around the "welding interface", the anode head and the anode column form a defect-free metallurgical transition layer through rotational friction welding, the grain size of the transition layer is ≤50 μm (refined grains improve strength), the interface resistance is ≤5 μΩ (reduce joule heat), and the thickness of the transition layer is 10%~30% of the diameter of the electrode column (optimize stress distribution).

[0026] 3. Material synergy: Tungsten copper alloy (high melting point) and beryllium copper or chromium copper and other copper alloys (high conductivity) form a gradient structure through dynamic recrystallization of friction welding, avoiding cracking caused by mismatch of thermal expansion coefficients.

[0027] Geometric synergy: The welding surface is designed as a circular ring structure, which increases the contact area and eliminates edge lack of penetration defects by using radial plastic flow of rotational friction welding.

[0028] The rotational friction welding has a top forging pressure ≥50 MPa (to make the copper column fully plastic deformation to fill the micro-pits of the tungsten head), a rotation speed ≥2000 rpm (to ensure that the interface temperature reaches the recrystallization temperature of copper but is lower than the melting point of tungsten), and an interface shear strength ≥200 MPa after welding.

[0029] 4、The present application has synergistic effect: microcosmic level adopts high speed + high pressure to make copper column dynamic softening, embeds in tungsten head surface micro groove, forms mechanical interlocking + metallurgical combination double reinforcement. Macroscopic level, welding residual stress is released through the thin wall design (thickness range) of the electrode column, avoids brittle fracture of tungsten copper head. Rotating friction welding makes tungsten copper-copper alloy interface performance close to integrated tungsten copper electrode, but because the copper alloy occupies the main volume is larger, and the density of copper alloy is almost reduced, so the weight is greatly reduced, and the service life meets the requirement of electromagnetic propulsion, thereby realizing synergistic effect. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a schematic view of the existing muzzle arcing device;

[0031] Figure 2 It is a schematic view of the current path of the welded lightweight long-life arcing electrode of the present application;

[0032] Figure 3 It is a schematic view of the welded lightweight long-life arcing electrode of embodiment 1;

[0033] Figure 4 It is a schematic view of the welded lightweight long-life arcing electrode of embodiment 2;

[0034] Figure 5 It is a tensile test curve after welding of tungsten copper and beryllium copper welding surface;

[0035] Figure 6 It is a schematic view of the current path before and after the armature exits the muzzle.

[0036] Among them, the reference signs are: flow guide anode 1a, flow guide cathode 1b, bypass anode 2a, bypass cathode 2b, fastener 3a, insulating spacer 4a, anode head 1, cathode head 2, anode column 3, cathode column 4. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0038] The welded lightweight long-life arcing electrode provided by the present application comprises an anode head 1, a cathode head 2, an anode column 3 and a cathode column 4. The anode head 1 and the cathode head 2 are electrode heads, and the anode column 3 and the cathode column 4 are electrode columns.

[0039] The material of the electrode head is single or composite metal good conductor material, such as tungsten copper alloy, which is welded with the electrode column at the cross section of round or circular structure, and the rest of the structure shape can be designed according to the actual application, which functions to guide the arc current between the armature and the rail, and realizes long service life.

[0040] The material of the electrode column is single or composite metal good conductor material, which is welded with the electrode head at the cross section of round or circular structure, and the rest of the structure shape can be designed according to the actual application, which functions to guide the residual current from the power supply to the arc eliminator, and realizes light weight.

[0041] As shown in Figure 2 , Figure 6 , the current path of the welded light weight long service life arc starting electrode is that the arc starter is connected in parallel with the rail at the muzzle area of the high speed electromagnetic propulsion device, is powered by the external power supply, and is connected in series with the cathode and anode of the arc starter through the cathode and anode of the high speed electromagnetic propulsion device, so that the current is conducted to the rail and armature path of the high speed electromagnetic propulsion device, the armature is accelerated to slide in the bore from the bore tail to the muzzle under the electromagnetic force, and when the armature exits the bore, the metal or plasma medium in the bypass electrode gap of the arc starter induces the gap breakdown discharge, so as to realize the arc starting effect.

[0042] Example 1:

[0043] As shown in Figure 3 , the material of the anode head 1 is tungsten, and the material of the cathode head 2 is tungsten, with an outer diameter of 50 mm and a thickness of 20 mm; the material of the anode column 3 is copper, and the material of the cathode column 4 is copper, with an outer diameter of 50 mm and a thickness of 80 mm; the electrode gap is 10 mm long. A current source is connected to the high speed electromagnetic propulsion device, which adopts an alternating current source of 60 Hz and 1 MA, and is applied to the anode and cathode of the arc starter. Compared with the integrated arc starting electrode, the structure has the characteristics of high strength, light weight and long service life; compared with other welded arc starting electrodes, the structure has the characteristics of high strength and high current. The electrode column and the electrode head adopt equal cross section columnar form, and the cross section adopts circular structure.

[0044] Figure 3 In the structure, the rails are arranged in upper and lower positions, which are not shown because they are shielded by the upper and lower flow guide electrode plates of the arc starter, and the left and right bore support members are respectively placed on the lower rails, and the upper rail is placed on the bore support member, so as to form the inner bore assembly. The device shell is sleeved outside the inner bore assembly, which can adopt fiber winding form or bolt pre-tightening form. The upper and lower flow guide electrode plates of the arc starter are respectively connected with the upper and lower rails.

[0045] Example 2:

[0046] As shown in Figure 4As shown, the material of the anode head 1 is tungsten, the material of the cathode head 2 is tungsten, the outer diameter is 70mm, and the thickness is 20mm; the material of the anode column 3 is copper, the material of the cathode column 4 is copper, the outer diameter is 50mm, and the thickness is 80mm; the electrode gap is 10mm. A current source is connected to a high-speed electromagnetic propulsion device, an alternating current source of 60Hz and 1MA is used, and is applied to the anode and cathode of the arc striking device. Compared with the integrated arc striking electrode, the structure has the characteristics of high strength, light weight and long service life; compared with other welding arc striking electrodes, the structure has the characteristics of high strength and high current. The electrode column and the electrode head adopt a non-equal cross-section columnar form, the cross-section adopts a circular structure, and the outer diameter of the electrode column is smaller than the outer diameter of the electrode head.

[0047] Figure 4 In the embodiment, the rails are arranged in an upper and lower arrangement, and are not shown because they are shielded by the upper and lower flow guide electrode plates of the arc striking device. The left and right barrel support members are respectively placed on the lower rails, and the upper rail is placed on the barrel support member, thereby forming an inner barrel assembly. The device shell is sleeved outside the inner barrel assembly, and can adopt a fiber winding form or a bolt pre-tightening form. The upper and lower flow guide electrode plates of the arc striking device are respectively connected with the upper and lower rails.

[0048] The application also provides a welding method of the welding type light-weight long-service-life arc striking electrode, comprising the following steps:

[0049] The melting point and softening temperature of the material of the electrode column are lower than the melting point and softening temperature of the material of the metal electrode head, frictional heat energy is generated through high-speed relative rotation of the two, the material of the electrode column is first melted, and permanent sealing connection is formed under the action of pressure. In this way, the material of the electrode head with greater density can be designed to be small in size and light in weight, so as to meet the requirements of light weight and long service life, and the specific steps include the following steps.

[0050] Step 1. Clean the electrode head and the electrode column with acetone.

[0051] Step 2. Place the electrode head and the electrode column in the welding equipment and position them.

[0052] Step 3. Start the rotary friction welding equipment, rotate the electrode column, and keep the electrode head stationary. The rotation speed of the electrode column is set to 3000r / min, and the axial pressure is 100MPa.

[0053] Step 4. Continue to apply the axial pressure to 200MPa, so that the electrode head and the electrode column are in close contact and plastic deformation occurs, and a weld is formed.

[0054] Step 6. After the welding is completed, cool and solidify the weld.

[0055] Step 7. After the welding is completed, polish and clean the size of the welding part exceeding the original outer diameter to ensure that the surface size is qualified.

[0056] Example 3:

[0057] The tensile property test was made on the friction welding electrode sample, the outer diameter of the electrode was 20 mm, the inner diameter was 14 mm, according to the calculation, it needed to withstand tensile force of more than 40 kN, after the tensile test, the welding strength of the friction welding electrode could meet the design requirements. As shown in the figure, the main coordinate unit was kN, corresponding to the lower segment polyline, the secondary coordinate unit was mm, corresponding to the upper segment polyline. Figure 5 Figure 5 The tensile test curve after welding the welding surface of tungsten copper and beryllium copper. After the tungsten copper electrode head and the beryllium copper electrode column were welded by rotary friction welding, a tensile testing machine was used to apply a tensile force of more than 40 kN, and 5 times of tensile test was continuously carried out within 2 minutes, the tensile force and elongation were detected, after the tensile test was finished, if there was no crack and no fracture on the welding surface, the welded part was qualified.

[0058] After 100 tests of the friction welding electrode, the mass loss was about 68 g; the one-piece copper alloy electrode was invalid after one test; the one-piece tungsten electrode was not adopted because it was too heavy and did not meet the lightweight requirement; the bolt-connected tungsten-copper electrode was not adopted because its structure did not meet the requirements of the muzzle working condition.​

Claims

1. A welding type lightweight long life arc striking electrode, characterized in that: It includes an anode head, a cathode head, an anode column, and a cathode column; the anode head and the anode column, and the cathode head and the cathode column are respectively welded on a circular or annular welding surface by rotational friction welding to form a solid metallurgical bond; the anode head and the cathode head are metal conductors resistant to arc erosion; the anode column and the cathode column are good metal conductors with a lower melting point than the corresponding electrode head; the electrodes are connected to the two ends of the muzzle track of the high-speed electromagnetic propulsion device, and induce electrode gap breakdown discharge when the armature is discharged from the muzzle.

2. A welding type lightweight long life arc striking electrode according to claim 1, characterized in that: The rotary friction welding is continuous rotary friction welding, and the welding interface has no holes or cracks, forming a full-section sealed connection.

3. A welding type lightweight long life arc striking electrode according to claim 1 or 2, characterized in that: The anode head and cathode head are made of tungsten-copper alloy, and the anode column and cathode column are made of copper alloy or brass.

4. The welding type lightweight long-life arc-starting electrode according to claim 1, characterized in that: The outer diameters of the anode column and cathode column are equal to or slightly smaller than the outer diameters of the corresponding anode head and cathode head, forming a coaxial cylindrical structure.

5. The welding type lightweight long life arc striking electrode according to claim 1, characterized in that: The thickness of the anode head and cathode head, the thickness of the anode column and cathode column are determined according to different calibers and weight requirements.

6. The welding type lightweight long life arc striking electrode according to claim 1, characterized in that: The coaxiality between the anode head and the anode column, and between the cathode head and the cathode column after welding is not greater than 0.1 mm.

7. The welding type lightweight long-life arc-starting electrode according to claim 1, characterized in that: The electrode gap length is indirectly calculated based on the caliber and residual current, and is no larger than the caliber of the electromagnetic propulsion device. The electrode outer diameter is calculated based on the electromagnetic force it receives.

8. A welding method for a welding type lightweight long-life arc-starting electrode, characterized in that: The steps include: Step 1. Clean the electrode head and electrode column; Step 2. Place the electrode head and electrode column in the welding equipment and position them; Step 3. Start the rotary friction welding equipment to rotate the electrode column and keep the electrode head stationary; Step 4. Continue to apply axial pressure to make the electrode head and electrode column in close contact and plastically deform to form a weld; Step 6. After welding is completed, the weld is cooled and solidified; Step 7. After welding is completed, grind and clean the weld that exceeds the original outer diameter to ensure that the surface size is qualified.

9. The welding method according to claim 8, characterized in that: In step 1, acetone is used for cleaning.

10. The welding method according to claim 8, characterized in that: In step 3, the rotation speed of the electrode column is set to 3000 r / min and the axial pressure is 100 MPa; in step 4, the axial pressure is continued to be applied to 200 MPa.

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