WO2019196494A1 - 一种电阻点焊电极帽 - Google Patents

一种电阻点焊电极帽 Download PDF

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Publication number
WO2019196494A1
WO2019196494A1 PCT/CN2018/121780 CN2018121780W WO2019196494A1 WO 2019196494 A1 WO2019196494 A1 WO 2019196494A1 CN 2018121780 W CN2018121780 W CN 2018121780W WO 2019196494 A1 WO2019196494 A1 WO 2019196494A1
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WIPO (PCT)
Prior art keywords
electrode cap
welding
groove
annular
resistance spot
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PCT/CN2018/121780
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English (en)
French (fr)
Inventor
杨上陆
王俊艳
陶武
Original Assignee
中国科学院上海光学精密机械研究所
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Application filed by 中国科学院上海光学精密机械研究所 filed Critical 中国科学院上海光学精密机械研究所
Priority to DE112018007461.7T priority Critical patent/DE112018007461T5/de
Priority to JP2021504557A priority patent/JP7256863B2/ja
Priority to US17/046,830 priority patent/US11890701B2/en
Publication of WO2019196494A1 publication Critical patent/WO2019196494A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K11/00—Resistance welding; Severing by resistance heating
    • B23K11/30—Features relating to electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
    • B23K35/0205—Non-consumable electrodes; C-electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K11/00—Resistance welding; Severing by resistance heating
    • B23K11/10—Spot welding; Stitch welding
    • B23K11/11—Spot welding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K11/00—Resistance welding; Severing by resistance heating
    • B23K11/30—Features relating to electrodes
    • B23K11/3009—Pressure electrodes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
    • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K11/00—Resistance welding; Severing by resistance heating
    • B23K11/16—Resistance welding; Severing by resistance heating taking account of the properties of the material to be welded

Definitions

  • the present invention relates to the field of resistance spot welding, and more particularly to a welding electrode cap for use in resistance spot welding between two or more layers of metal workpieces.
  • the aluminum alloy material has the advantages of high strength, light weight, excellent corrosion resistance, and is suitable for various molding methods, the aluminum alloy is used instead of the steel plate material for welding, and the structural weight can be reduced by more than 50%, and is widely used in automobile bodies.
  • connection method of the body aluminum alloy in automobile manufacturing is mainly based on the mechanical connection method of riveting.
  • Riveting is a method of high cost, complicated process, poor surface quality and increased body weight.
  • An all-aluminum body or a hybrid body usually requires more than 1500 nails.
  • Resistance spot welding uses the workpiece itself and the resistance heat generated by each other to melt the material to achieve the connection. Since it does not require filling materials during the joining process, high production efficiency and easy automation, the method is widely used in automobile body manufacturing. For example, in the engine cover, door and other parts, with the application of aluminum alloy in automobiles, automobile manufacturers hope to continue to connect aluminum alloy by resistance spot welding.
  • a welding contact surface has a groove at the center. Electrode cap.
  • a technical solution adopted by the present invention is to provide a resistance spot welding electrode cap, comprising:
  • a contact surface 3 having a weld surface 31, a circumference 32, and a groove 33, the groove 33 being located at the center of the contact surface 3, the upper edge of which
  • the circumference 32 is the outer diameter of the welding surface 31;
  • side 2 is a transition region of the electrode cap body 1 to the contact surface 3, and the shape of the side surface 2 is a curved surface or a tapered surface;
  • the upper and lower surfaces of the side surface 2 are respectively connected to the contact surface 3 and the other end of the electrode cap body 1 in a curved or chamfered manner.
  • the shape of the groove 33 is a curved surface as a whole, or the bottom is a flat surface, the portion connected to the welding surface 31 is curved with a curved surface or a tapered surface, or the middle is a curved convex portion, and the welding surface ( 31)
  • the connecting portion is a transition of a curved surface or a tapered surface.
  • the shape of the groove is a spherical surface having an outer diameter d 3 of 2-15 mm; preferably 2-10 mm.
  • the groove 33 is joined to the weld surface 31 by a circular arc or a chamfer.
  • the side surface 2 and the welding surface 31 and the electrode cap body 1 are connected by a circular arc or a chamfer.
  • the radius of curvature of the curved surface is greater than or equal to the circumferential radius of the electrode cap body 1.
  • the inclination angle of the tapered surface is 0-90°, preferably 10-80°.
  • the depth h of the groove 33 is from 0.1 to 2 mm; or more preferably from 0.1 to 1.2 mm.
  • the radius of curvature of the arcuate surface of the groove 33 is 1-50 mm, and when the bottom of the groove is flat, the plane is a circle having a radius of 0.1-10 mm.
  • the soldering surface 31 is an annular plane, or an annular spherical surface on the same side of the core of the electrode cap body, or an annular spherical surface on the opposite side of the spherical core and the electrode cap body, or an upwardly convex circular arc. surface.
  • the outer diameter ranges from 2 to 30 mm; preferably, from 6 to 20 mm.
  • the radius of the ball on which the weld surface 31 is located is 10-100 mm.
  • the radius of curvature of the arc is 1-10 mm, and the vertical distance between the highest point of the curved surface and the plane of the lowest point is 0.1-5 mm.
  • the resistance spot welding electrode cap further includes an annular ridge 4 on the weld face 31 or groove 33, the cross-sectional shape of which is a straight line or a curve or a combination of a straight line and a curve.
  • the resistance spot welding electrode cap further includes a groove 43 formed between two adjacent annular ridges 4.
  • the annular ridge 4 has a projection height H of 20-500 um.
  • the number of annular ridges 4 is 0-5.
  • the spacing between adjacent two annular ridges 4, that is, the width of the grooves 43 is 50-2000 um.
  • the mechanism of the invention is as follows: for welding two layers of metal workpieces, the two sides of the metal workpiece are first contacted by the pressure and current of the welding surface with the central depression, and the contact portion is subjected to the action of the ring electrode. The area will generate resistance heat and form an annular molten pool. With the extension of the welding time, the annular molten pool will grow toward the center under the heat conduction with the gradual contact of the central area, due to the central area of the two metal workpieces corresponding to the grooves. (Inside of the solder joint) is small and is not in contact with the electrode cap. The heat is concentrated on the outside.
  • the metal material in the contact area melts and plastically deforms, it will expand and expand toward the center recess of the electrode, and the new contact surface of the center is generated again.
  • the resistance heat is generated at the new contact surface, causing the annular molten pool to grow toward the center of the ring, so that the contact portions of the two metal materials corresponding to the grooves form a nugget to complete the welding.
  • the initial contact area of the electrode cap of the present invention with the metal workpiece is reduced, the overall heat generation is concentrated, the heat dissipation is slowed, and as the welding progresses, the contact area becomes larger and the heat dissipation becomes faster, so
  • the electrode cap reduces the welding current required to form solder joints of the same size, saves power costs, and increases electrode life.
  • the annular molten pool is formed first, the presence of the central groove causes the annular molten pool to be externally inward.
  • the plastic metal material is squeezed into the groove center region under the action of pressure and current, which helps to avoid the occurrence of pores, splashes and welding deformation at the edge of the solder joint, thereby enabling Increase the diameter of the nugget and increase the strength of the solder joint.
  • the annular ridge can pierce the oxide film on the surface of the aluminum alloy during contact, thereby reducing the contact resistance, and can increase the contact area and enhance heat dissipation, thereby reducing the electrode welding surface and the aluminum alloy plate. Contact the heat of the surface to increase the life of the electrode.
  • Figure 1 shows a schematic view of an electrode cap having a groove in the center of the contact surface.
  • Fig. 2 shows an embodiment of a cross-sectional view taken along line A-A of Fig. 1.
  • Figure 3 shows an embodiment of the cross-sectional view taken along line A-A of Figure 1 in which the weld face is an annular plane and the groove is spherical.
  • Figure 4 shows an embodiment of the cross-sectional view taken along line A-A of Figure 1 in which the weld face is an annular plane, the bottom of the groove is a flat surface, and the weld surface is curved with a curved surface.
  • Figure 5 shows an embodiment of the cross-sectional view taken along line A-A of Figure 1 in which the weld face is an annular plane with an arcuate boss in the middle of the groove and a transition to the weld face.
  • Fig. 6 shows an embodiment in which the welding face is an annular spherical surface on the same side as the center of the electrode cap body, and the groove is a spherical surface, taken along the line A-A in Fig. 1.
  • Fig. 7 shows an embodiment in which the welding surface is an annular spherical surface on the same side as the center of the electrode cap body, and the bottom of the groove is a flat surface, and a cross-sectional view taken along the line A-A of Fig. 1 with the curved surface of the welding surface.
  • Fig. 8 shows an embodiment in which the welding surface is an annular spherical surface on the same side of the core and the electrode cap body, the arc-shaped projection in the middle of the groove, and the cross-section of the welding surface connecting portion in a curved plane, taken along the line A-A in Fig. 1.
  • Fig. 9 shows an embodiment in which the welding face is an annular spherical surface on the opposite side of the center of the electrode cap body, and the groove is a spherical surface, taken along the line A-A in Fig. 1.
  • Fig. 10 shows an embodiment in which the welding surface is an annular spherical surface on the opposite side of the core and the electrode cap body, and the bottom of the groove is a flat surface, and a cross-sectional view taken along the line A-A of Fig. 1 with the curved surface of the welding surface.
  • Fig. 11 shows an embodiment in which the welding surface is an annular spherical surface on the opposite side of the center of the electrode and the electrode cap body, the arc-shaped boss is in the middle of the groove, and the cross-sectional view in Fig. 1 in Fig. 1 is transitioned to the curved surface.
  • Figure 12 shows an embodiment of the cross-sectional view taken along line A-A of Figure 1 in which the weld face is an upwardly convex annular curved surface and the groove is spherical.
  • Figure 13 shows an embodiment of the cross-sectional view taken along line A-A of Figure 1 in which the weld face is an upwardly convex annular curved surface with the bottom of the groove being planar and transitioning with the weld surface.
  • Figure 14 shows an embodiment in which the weld face is an upwardly convex annular curved surface with an arcuate boss in the middle of the groove and a cross-sectional view taken along line A-A of Fig. 1 in which the joint portion of the weld face is curved.
  • Figure 15 shows a schematic view of an electrode cap having a groove in the center of the contact surface and an annular ridge on the weld face.
  • Fig. 16 is an enlarged view showing a region of a welding surface of the electrode cap of Fig. 15.
  • Fig. 17 is a view showing an embodiment of a partial cross-sectional view taken along line B-B of Fig. 15.
  • Fig. 18 shows another embodiment of a cross-sectional view taken along line B-B of Fig. 15.
  • Fig. 19 shows an embodiment of a cross-sectional shape of an annular ridge on both sides which is a straight line and whose top is a circular arc tangent to the two sides.
  • Figure 20 shows an embodiment of the cross-sectional shape of an annular ridge with a symmetrical curve on both sides and a top arc that is tangent to the curve on both sides.
  • Figure 21 shows an embodiment of the cross-sectional shape of the annular ridges which are straight at both the top and the sides.
  • Figure 22 shows an embodiment of the cross-sectional shape of the annular ridges on both sides being straight and the top being a circular arc intersecting the two sides.
  • Figure 23 shows an embodiment of the cross-sectional shape of the annular ridges with different curves on both sides and a top curve connected to the two sides of the curve.
  • Figure 24 shows an embodiment of the cross-sectional shape of a circular ridge with a symmetrical curve on both sides and a straight line at the top.
  • Figure 25 shows an embodiment of the cross-sectional shape of an annular ridge with one side being a straight line, the other side being a curve, and the top being a curve or a straight line.
  • Figure 26 shows an embodiment of the cross-sectional shape of an annular ridge having an entire cross section.
  • Fig. 27 shows an embodiment of a cross-sectional view taken along line B-B of Fig. 15 in which the welding face 31 is an annular plane and the groove 33 is a spherical surface with the annular ridge on the welding surface.
  • Figure 28 shows an embodiment of a cross-sectional view of section B-B of Figure 15 in which the weld face is an annular plane and the groove is a spherical surface with the annular ridge on both the weld face and the groove.
  • Figure 29 shows an embodiment in which the weld face is an annular plane, the bottom of the groove is a flat surface, and the annular ridge is located on the weld face in the cross section taken along line B-B in Figure 15 when the groove is transitioned with the weld face.
  • Figure 30 shows an embodiment in which the weld face is an annular plane, the middle of the groove is an arcuate boss, and the cross-sectional view of the section B-B of Figure 15 in which the annular ridge is located on the weld face when the joint of the weld face is curved.
  • Figure 31 shows an embodiment of a cross-sectional view taken along line B-B of Figure 15 in which the weld face is the annular spherical surface on the same side as the center of the electrode cap body and the groove is a spherical surface with the annular ridge on the weld face.
  • Figure 32 shows an embodiment of a cross-sectional view of the BB section in Figure 15 with the weld surface being the same spherical surface as the center of the electrode cap body, the bottom of the groove being a flat surface, and the arcuate surface transitioning with the weld surface. example.
  • Figure 33 shows an annular spherical surface on the same side of the center of the electrode body as the welding surface, the arc-shaped boss in the middle of the groove, and the BB section in Figure 15 where the annular ridge is located on the welding surface when the connecting portion of the welding surface is curved.
  • FIG. 33 shows an annular spherical surface on the same side of the center of the electrode body as the welding surface, the arc-shaped boss in the middle of the groove, and the BB section in Figure 15 where the annular ridge is located on the welding surface when the connecting portion of the welding surface is curved.
  • Figure 34 shows an embodiment of a cross-sectional view of the section B-B of Figure 15 in which the weld face is an upwardly convex annular curved surface, the groove being a spherical surface with the annular ridge on both the weld face and the groove.
  • Figure 35 is a cross-sectional view of the BB section of Figure 15 in which the welding surface is an upwardly convex annular curved surface, the bottom of the groove is a flat surface, and the arcuate surface transitions with the welding surface when the annular ridge is located on the welding surface and is located on the groove.
  • Fig. 36 is a view showing the overall overall view of the metal workpiece during resistance spot welding.
  • Fig. 37 is a schematic cross-sectional view showing the initial stage of welding when welding is carried out using the present invention when the annular surface of the electrode cap of the present invention is not provided with an annular ridge.
  • Fig. 38 is a schematic cross-sectional view showing the initial stage of welding when welding is carried out using the present invention when an annular ridge is provided on the welding surface of the electrode cap of the present invention.
  • Figure 39 shows the cross-sectional shape of a solder joint after resistance spot welding of two 2 mm 5182-O aluminum alloys using a common electrode cap.
  • Figure 40 is a view showing the cross-sectional shape at the solder joint after resistance spot welding of two 2 mm 5182-O aluminum alloys using the electrode cap of Example 1 of the present invention.
  • the resistance spot welding electrode cap of the present embodiment includes a substantially cylindrical electrode cap body 1, and a contact surface 3 between the electrode and the welding metal material.
  • the body 1 has an electrode mounting passage 11 at one end and a circumference 12 at the other end.
  • the contact surface 3 includes a weld surface 31, a circumference 32, and a groove 33.
  • the groove 33 is located in the central region of the contact surface 3.
  • the electrode cap further comprises a side surface 2 which is a transitional region of the circumference 12 of the body 1 that transitions to the circumference 32 of the contact surface 3, the side surface 2 being in the form of a curved surface, it being noted that the side surface 2 may also be a conical shape.
  • the radius of curvature of the curved surface is greater than or equal to the circumferential radius of the electrode cap body 1; when the side surface 2 is a tapered surface, the inclined angle of the tapered surface is 0-90°, preferably 10-80°.
  • the upper surface of the side surface 2 is a portion in contact with the groove, and the lower surface is a portion in contact with the body 1.
  • the diameter of the circumference 12 is the same as the diameter of the circumference 32, the side surface 2 becomes a part of the electrode cap body 1.
  • the diameter of the circumference 12 is the diameter of the electrode cap body 1
  • the radius of the circumference 12 is the radius of the electrode cap body 1.
  • Side 2 can also be of other suitable shapes.
  • One end of the body 1 refers to one end connected to the resistance spot welding machine during resistance spot welding, and the other end refers to one end close to the contact surface of the welding workpiece.
  • the shape of the electrode mounting passage 11 is a circular or cylindrical shape, and the shape of the electrode mounting passage 11 may be other suitable shapes.
  • the circumference 32 is parallel to the circumference 12, and the circumference 32 is understood to be the circumference of the circumference 12 whose diameter has changed along the axis perpendicular to the axis of the body 1, the line center of the circumference 32 and the center of the circumference 12 and The axes of the bodies 1 coincide, and the diameter d 2 of the circumference 32 is less than or equal to the diameter d 1 of the circumference 12.
  • the groove 33 can be understood as a hole having a certain shape dug at the intermediate position of the contact surface 3 and extending downwardly a certain distance, the groove 33 being in the shape of a curved surface or in the middle of the plane, and the annular welding surface 31
  • the contact portion is a curved surface, or an arc-shaped boss in the middle, and the portion in contact with the welding surface 31 is a curved surface.
  • the depth of the groove 33 is from 0.1 to 2 mm; preferably, from 0.1 to 1.2 mm.
  • the depth of the groove 33 referred to herein is the vertical distance from the plane in which the edge of the upper portion of the groove 33 in contact with the welding face 31 is located to the bottommost portion of the groove 33.
  • the shape of the groove 33 is a spherical surface, and when the shape of the groove 33 is a spherical surface, the outer diameter d 3 is 2-15 mm; preferably, 4-12 mm.
  • the welding surface 31 is an annular plane or an annular spherical surface on the same side of the core of the electrode body or an annular spherical surface on the opposite side of the core and the electrode cap body or an upwardly convex annular curved surface.
  • the center of the ball and the opposite side of the electrode cap body and the different sides of the core and the electrode cap body refer to the welding surface 31 as a critical surface, and the direction in which the spherical core approaches the electrode cap body 1 is the same side as the electrode cap body.
  • the direction in which the center of the ball is away from the electrode cap body 1 is the direction from the opposite side of the electrode cap body.
  • the outer diameter range that is, the circumference 32 has a diameter of 2-30 mm, preferably 5-20 mm; when the welding surface 31 is an annular spherical surface, the radius of the ball where the welding surface 31 is located is 10- 100mm; When the welding surface 31 is an upwardly convex annular curved surface, the radius of curvature of the arc is 1-10 mm, and the vertical distance between the highest point of the arc surface and the plane of the lowest point is 0.1-5 mm.
  • FIG. 3-14 show various embodiments of the cross-sectional view taken along line A-A of Fig. 1 when the shapes of the weld face 31 and the groove 33 are combined.
  • 1A cross-sectional view of the cross-sectional view of the welding plane can be an annular plane
  • the groove is a spherical surface ( Figure 3) or the welding surface is an annular plane
  • the bottom of the groove is a plane, with a curved surface transition between the welding surface ( Figure 4) or
  • the welding surface is an annular plane
  • the middle of the groove is an arc-shaped boss
  • the curved surface is connected with the welding surface (Fig.
  • the welding surface is the annular spherical surface of the spherical core and the same side of the electrode cap body, and the groove is spherical (figure 6)
  • the welding surface is an annular spherical surface on the same side of the core of the electrode and the body of the electrode cap.
  • the bottom of the groove is a flat surface, and the arc surface is transitioned with the welding surface (Fig. 7) or the welding surface is the same side of the spherical body and the electrode cap body.
  • the annular spherical surface, the arc-shaped boss in the middle of the groove, the arc-shaped transition (Fig.
  • the welding surface is the annular spherical surface of the spherical body and the opposite side of the electrode cap body, and the groove is spherical (Fig. 9) or
  • the welding surface is an annular spherical surface on the opposite side of the spherical core and the electrode cap body, and the bottom of the groove is a plane, a curved surface transition with the welding surface (Fig. 10) or a welding surface is a circular spherical surface of the spherical core and the opposite side of the electrode cap body.
  • the middle of the groove is an arc-shaped boss, the arc-face transition (Fig.
  • the weld surface is a circular arc-shaped surface which is convexly connected to the welded surface, and the groove is spherical (Fig. 12)
  • the welding surface is an upwardly convex annular curved surface
  • the bottom of the groove is a flat surface
  • a curved surface transition with the welding surface Fig. 13
  • the welding surface is upwardly convex
  • the groove is curved in the middle.
  • the boss and the joint portion of the weld surface are in the shape of a curved transition (Fig. 14).
  • the electrode cap of the present invention may be made of any conductive and thermally conductive material, such as copper alloy, including copper chromium (CuCr) alloy, copper chromium zirconium (CuCrZr) alloy, copper with added alumina particles.
  • copper alloy including copper chromium (CuCr) alloy, copper chromium zirconium (CuCrZr) alloy, copper with added alumina particles.
  • An alloy or other various copper alloys useful as electrode materials; the aluminum alloys described above may comprise a deformed aluminum alloy or a cast aluminum alloy, including an aluminum alloy substrate having a coated or uncoated surface, such as an aluminum-magnesium alloy, aluminum Aluminum alloys such as silicon alloy, aluminum magnesium silicon alloy, aluminum zinc alloy, and aluminum copper alloy.
  • the material state may include various tempering, including annealing, strain strengthening, solid solution strengthening and the like.
  • the thickness of the aluminum substrate is generally between 0.3 mm and 6.0 mm, preferably between 0.5 mm and 3.0 mm.
  • the resistance spot welding electrode cap of this embodiment is similar to that of Embodiment 1, except that the welding surface 31 or the groove 33 of the present embodiment has a convex annular ridge 4, as shown in FIG. 15-16, adjacent to each other.
  • a groove 43 is formed between the two annular ridges.
  • the annular ridge 4 can be understood as an annular structure formed by a plane of a certain structure of the cross-section 44 around the central axis of the electrode cap, wherein the lower portion of the cross-section 44 is in contact with the welding surface 31, and the entire cross-section 44 is The weld face 31 is perpendicular.
  • the central axis of the electrode cap is a straight line passing through the center of the circumference 12 and perpendicular to the circumference 12. It is to be noted that the number of the annular ridges is not limited to two, and may be one or more as needed.
  • the raised annular ridge 4 has two convex manners on the welding surface 31 as shown in FIGS. 17 and 18.
  • the height H of the annular ridge 4 relative to the welding surface 31 may be 20-500 um.
  • the height of the projections referred to herein refers to the vertical distance H from the lower portion of the annular ridge to the top in the direction perpendicular to the surface of the weld surface 31 or the groove of the annular ridge 4.
  • the width d 4 of the groove 43 formed by the spacing between two adjacent annular ridges, that is, the distance between the two annular ridges is 50-3000 um.
  • the width d 4 of the groove 43 between adjacent two annular ridges referred to herein means that a partial cross-sectional view of the electrode cap with the annular ridge is located at two adjacent annular ridges 41 as shown in FIG.
  • the distance between the two points 45 and 46 on the 42 points, the points 45 and 46 are located on the two sides adjacent to the annular ridges 41 and 42, and the line between the two points is parallel to the welding face 31.
  • the width d 5 of the annular ridge may be from 200 to 3000 ⁇ m, or more preferably from 500 to 2000 ⁇ m.
  • the width d 5 of the annular ridge referred to herein refers to the distance between two points on the two sides of the same annular ridge which are located on the same cross section of the annular ridge. It should be noted that when the number of the annular ridges is three or more, the groove widths d 4 between the adjacent two annular ridges may be the same or different, and the widths d 5 of the respective annular ridges may be the same or different.
  • a possible shape structure of the annular ridge cross section 44 is shown (a represents the lower portion of the cross section, b represents the top of the cross section, c represents the sides of the cross section), and the shape of the cross section 44 may be
  • the sides are straight, the top is an arc tangent to the two sides (Fig. 19) or the two sides are symmetrical, the top is an arc tangent to the curves on both sides (Fig. 20) or both sides and both sides are Straight line (Fig. 21) or a straight line on both sides, the top is an arc that intersects the line on both sides (Fig. 22) or a different curve on both sides, the top is a curve connected to the curve on both sides (Fig.
  • FIG. 23 A structure that is a symmetrical curve, with a straight line at the top (Fig. 24) or a straight line on one side, a curved line on the other side, a curve or straight line at the top (Fig. 25), or a semicircular cross section (Fig. 26).
  • Fig. 24 A structure that is a symmetrical curve, with a straight line at the top (Fig. 24) or a straight line on one side, a curved line on the other side, a curve or straight line at the top (Fig. 25), or a semicircular cross section (Fig. 26).
  • the cross-sectional structure of the annular ridges described above is only a preferred structure, and may be other structures suitable for the shape of the annular ridge.
  • the position of the annular surface is shown in the position of the welding surface 31 and the groove 33 when the shapes of the welding surface 31 and the groove 33 are different. It should be noted that only some annular ridges are listed on the welding surface and Some preferred locations on the recess, the annular ridges may be located solely on the weld face 31 or may be located separately on the groove 33 or on both the weld face 31 and the groove 33, and the annular ridges on the weld face 31 and the groove 33 The number can be randomly selected according to the usage.
  • This embodiment discloses an apparatus and a process for welding an aluminum alloy workpiece using the electrode cap of the present invention.
  • 5 is a welding position 8 which can be used for resistance spot welding to join the first aluminum alloy workpiece 6 and the second aluminum alloy workpiece 7.
  • the welding torch 5 includes a first welding gun arm 51, a second welding gun arm 52, a first welding electrode cap 53, and a second welding electrode cap 54.
  • the first and second aluminum alloy workpieces 6, 7 are composed of an aluminum alloy such as an aluminum-magnesium alloy, an aluminum-silicon alloy, an aluminum-magnesium-silicon alloy or an aluminum-copper alloy, and the thickness of the aluminum alloy workpiece is 0.5 to 3 mm.
  • the aluminum alloy workpiece may be a 2.0 mm thick 5182-O aluminum alloy.
  • the aluminum alloy workpiece during welding may be two (for example, only 6 and 7) or a combination of two or more, and the thickness of each aluminum alloy workpiece may be the same or different.
  • workpiece refers to a wide range of metal sheets, protrusions, castings, and other aluminum alloy parts or steel, magnesium alloy workpieces that can be resistance spot welded.
  • the torch arms 51, 52 are typically part of a larger automated welding operation, typically including Type C, Type X and other types of structural shapes, typically implemented by robots or automated components, well understood in the art. of.
  • the first and second torch arms 51 and 52 have mounted first and second welding electrode caps 53 and 54 as described in Embodiments 1 and 2, and during spot welding, the torch arms are operated to cause the electrode cap 53 and 54 can be accurately placed against the workpieces 6 and 7, and the pressure and current are conducted through the torch arm and the electrode cap, so that the bonding portions 8 of the workpieces 6, 7 are melted and a spot welded joint is formed.
  • the two electrode caps 53 and 54 may be of various structures as described in Embodiments 1 and 2, and the structures of 53 and 54 may be the same or different.
  • Fig. 37 is a schematic cross-sectional view showing the initial stage of welding when welding using the electrode cap of the embodiment 1 of the present invention.
  • the electrodes 53 and 54 have the same structural size.
  • the welding torch transmits pressure and current through the welding surface 31, and the contact portion of the two metal materials 6 and 7 is subjected to resistance heat in the region where the ring electrode acts, thereby forming the nugget 9, and further Form an annular weld pool.
  • the outer side of the two-layer metal workpiece is first contacted, and the area where the contact portion is subjected to the ring electrode generates resistance heat and forms an annular molten pool. As the welding time is extended and the central region is gradually contacted, the annular molten pool is centered under heat conduction.
  • the heat is concentrated on the outer side, and the electrodes are directed toward the electrodes as the metal material in the contact regions is melted and plastically deformed.
  • the central depression is squeezed and expanded, and the new contact surface is generated again.
  • the resistance heat is generated at the new contact surface, causing the annular molten pool to grow toward the annular center, thereby forming the nugget of the contact portion of the two metal materials corresponding to the groove. , complete the welding.
  • the initial contact area of the electrode cap of the present invention with the metal workpiece is reduced, the overall heat generation is concentrated, the heat dissipation is slowed, and as the welding progresses, the contact area becomes larger and the heat dissipation becomes faster, so the common electrode cap is The welding current required to form solder joints of the same size is reduced, the power cost is saved, and the life of the electrode is increased.
  • the annular molten pool is first formed, the presence of the central groove causes the annular molten pool to grow from the outside to the inside, The common electrode cap molten pool grows from the inside to the outside.
  • the plastic metal material is squeezed to the central groove area of the electrode under the action of pressure and current, which helps to avoid the occurrence of pores and splashes at the edge of the solder joint, thereby increasing the diameter of the nugget. Increase the solder joint strength.
  • the annular ridge can pierce the oxide film on the surface of the aluminum alloy during contact, thereby reducing the contact resistance, and can increase the contact area and enhance heat dissipation, thereby reducing the contact surface between the electrode welding surface and the aluminum alloy plate. The heat that increases the life of the electrode.
  • Figure 38 is a schematic cross-sectional view showing the initial stage of welding when welding using the electrode cap of Example 2 of the present invention.
  • the welding principle is similar to the welding principle of FIG.
  • Figure 39 shows the cross-sectional shape of the solder joint after resistance spot welding of two 5182-O2 aluminum alloys with a thickness of 2 mm using a common electrode cap. It can be seen from the figure that the nugget diameter is only 6.08 mm. There are obvious shrinkage defects in the inside, the splash is serious, and the edge welding deformation is large, which results in low solder joint strength.
  • two aluminum alloys are subjected to resistance spot welding on two 5182-O aluminum alloys having a thickness of 2 mm.
  • the cross-sectional shape of the solder joint it can be seen that the nugget diameter reaches 8.23mm, and there is no obvious welding defect inside, no spatter occurs, no obvious deformation at the edge of the solder joint, which greatly improves the solder joint strength.

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Abstract

一种电阻点焊电极帽，此电极帽的焊接接触面（3）中心上具有凹槽（33），焊接时，由于凹槽（33）的存在，电极帽与待焊金属工件的接触面积减小，初期整体产热集中于焊点外圈、散热变慢，有助于熔核由外向内形成，并且由于凹槽（33）的存在，金属工件向电极中心凹槽（33）处扩展，从而增大焊点熔核，减小飞溅和变形，与传统电极帽相比，形成相同大小的焊点所需要的焊接电流更低，节省电力成本；并且使用相同的电流时所得焊点强度和稳定性更高，且焊接缺陷更少。

Description

一种电阻点焊电极帽 技术领域
本发明涉及电阻点焊领域，更具体地涉及两层或多层金属工件之间进行电阻点焊时使用的焊接电极帽。
背景技术
随着全球变暖、能源枯竭问题的逐渐加剧，汽车的尾气排放及能源消耗越来越严重，实验证明汽车质量降低一半，燃料消耗也会降低将近一半，由于环保和节能的需要，汽车的轻量化已经成为世界汽车发展的潮流。由于铝合金材料具有强度高、质量轻、耐腐蚀性能优良、适合多种成型方法等优点，采用铝合金代替钢板材料焊接，结构重量可减轻50％以上，被广泛应用于汽车车身中。
目前汽车制造中车身铝合金的连接方法主要以铆接的机械连接方法为主。而铆接是一种成本较高，工序复杂，表面质量差，增加车身重量的方法，一辆全铝车身或混合车身，通常需要1500个以上的钉子。电阻点焊利用工件本身及相互之间的电阻产热来熔化材料实现连接，由于其在连接过程中不需要填充材料，生产效率高且容易实现自动化，所以该方法被广泛应用在汽车车身制造中，例如发动机盖、车门等部位，随着铝合金在汽车中的应用，汽车制造商期望能继续采用电阻点焊对铝合金进行连接。
但是由于铝合金其本身的物理性质，采用普通的点焊工艺进行焊接时存在诸多问题。由于铝合金的高导电性、高导热性导致其在点焊过程中需要特别大的电流和压力，而伴随着大电流和高电极压力的使用，导致其在焊接时就需要更高的制造成本。而且由于铝合金的塑型温度区间较窄而导致焊接时飞溅及内部缺陷严重，焊接变形较大。表面高电阻氧化膜的存在又会导致在点焊过程中焊接电极磨损较快、电极寿命短进而导致焊点强度下降，表面质量差。
因此，需要一种能够获得更高焊接强度、电极寿命更长、低成本，更容易推广的电阻点焊铝合金的方法。
发明内容
本发明为了解决铝合金电阻点焊需要较大焊接电流，焊接飞溅、缺陷严重而焊接强度相对较低，焊接质量不稳定，电极寿命低等问题，提出了一种焊接接触面中心具有凹槽的电极帽。
为解决上述问题，本发明采用的一个技术方案是：提供一种电阻点焊电极帽，包括：
呈圆柱状的电极帽本体1；
具有焊面31、圆周32、凹槽33的接触面3，凹槽33位于接触面3的中心，其上部边缘
与焊面31相连接，圆周32为焊面31的外径；
侧面2，侧面2为电极帽本体1到接触面3的过渡区域，侧面2的形状为弧面或锥面；
侧面2的上下表面分别与接触面3及电极帽本体1的另一端以弧面或倒角的形式相连接。在另一优选例中，凹槽33的形状为整体为一弧面，或底部为平面、与焊面31连接部分以弧面或锥面过渡，或中间为弧形凸台、与焊面(31)连接部分以弧面或锥面过渡。
在另一优选例中，凹槽的形状为球面，其外径d 3为2-15mm；优选地，2-10mm。
在另一优选例中，凹槽33与焊面31以圆弧或倒角连接。
在另一优选例中，侧面2与焊面31以及与电极帽本体1之间以圆弧或倒角连接。
在另一优选例中，当侧面2为弧面时，弧面的曲率半径大于等于电极帽本体1的圆周半径。
在另一优选例中，当侧面2为锥面时，锥面的倾角为0-90°优选地，10-80°。
在另一优选例中，凹槽33的深度h为0.1-2mm；或更优选地，0.1-1.2mm。
在另一优选例中，凹槽33弧面的曲率半径为1-50mm，当凹槽底部为平面时，平面是半径为0.1-10mm的圆。
在另一优选例中，焊面31为环形平面，或为球心与电极帽本体同侧的环形球面，或为球心与电极帽本体异侧的环形球面，或为向上凸起的环形弧面。
在另一优选例中，当焊面31为
环形平面时，其外径范围为2-30mm；优选地，6-20mm。
在另一优选例中，当焊面31为环形球面时，焊面31所在的球的半径为10-100mm。
在另一优选例中，当焊面31为向上凸起的环形弧面时，弧的曲率半径为1-10mm，弧面最高点与最低点所在平面的垂直距离为0.1-5mm。
在另一优选例中，电阻点焊电极帽还包括位于焊面31或凹槽33上的环形脊4，环形脊的截面形状为直线或曲线或直线与曲线的组合。
在另一优选例中，电阻点焊电极帽还包括相邻两个环形脊4之间形成的沟槽43。
在另一优选例中，环形脊4凸起高度H为20-500um。
在另一优选例中，环形脊4的数量为0-5个。
在另一优选例中，相邻两个环形脊4之间的间距即沟槽43的宽度为50-2000um。
应理解，在本发明范围内中，本发明的上述各技术特征和在下文(如实施例)中具体描述 的各技术特征之间都可以互相组合，从而构成新的或优选的技术方案。限于篇幅，在此不再一一累述。
本发明的机理为：以焊接两层金属工件为例，焊接时，通过在具有中心凹陷的焊面的压力与电流的作用下，两层金属工件外侧首先接触，相接触部分受到环形电极作用的区域会产生电阻热、形成环形熔池，随着焊接时间的延长，随着中心区域的逐渐接触，环形熔池在热传导作用下向中心生长，由于与凹槽相对应的两金属工件中心区域面积(焊点内侧)较小并且未与电极帽接触，热量集中于外侧，随着接触区域金属材料的熔化和塑性变形，其会向电极中心凹陷处挤压扩展，进而中心新的接触面又产生，电阻热在新的接触面产生，导致环形熔池向环形中心生长，进而使与凹槽相对应的两金属材料接触部分形成熔核，完成焊接。
技术效果：由于凹槽的存在本发明的电极帽初期与金属工件的接触面积减小，整体产热集中、散热变慢，并随着焊接的进行，接触面积变大散热变快，所以与普通电极帽相比形成相同大小的焊点所需要的焊接电流会降低，节省电力成本，并提高电极寿命；另外，因为环形熔池首先形成，中心凹槽的存在，会使环形熔池由外向内生长，与普通电极帽熔池从内向外生长相反，塑性金属材料会在压力及电流作用下被挤向电极中心凹槽区域，有利于避免在焊点边缘产生气孔、飞溅及焊接变形，从而能够增大熔核直径、提高焊点强度。
存在环形脊的情况下，在接触时，环形脊可以刺破铝合金表面的氧化膜，进而降低接触电阻，并且可以增大接触面积，增强散热，以此来减小电极焊接面与铝合金板接触面的热量，从而提高电极的使用寿命。
附图说明
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图做简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的可替代的实施方式。
图1表示接触面中心具有凹槽的一个电极帽的示意图。
图2表示图1中A-A截面的剖视图的一个实施例。
图3表示焊面为环形平面，凹槽为球面的图1中A-A截面剖视图的一个实施例。
图4表示焊面为环形平面，凹槽底部为平面、与焊面之间以弧面过渡的图1中A-A截面剖视图的一个实施例。
图5表示焊面为环形平面，凹槽中间为弧形凸台、与焊面连接部分以弧面过渡的图1中A-A截面剖视图的一个实施例。
图6表示焊面为球心与电极帽本体同侧的环形球面，凹槽为球面的图1中A-A截面剖视图的一个实施例。
图7表示焊面为球心与电极帽本体同侧的环形球面，凹槽底部为平面、与焊面之间以弧面过渡的图1中A-A截面剖视图的一个实施例。
图8表示焊面为球心与电极帽本体同侧的环形球面，凹槽中间为弧形凸台、与焊面连接部分以弧面过渡的图1中A-A截面剖视图的一个实施例。
图9表示焊面为球心与电极帽本体异侧的环形球面，凹槽为球面的图1中A-A截面剖视图的一个实施例。
图10表示焊面为球心与电极帽本体异侧的环形球面，凹槽底部为平面、与焊面之间以弧面过渡的图1中A-A截面剖视图的一个实施例。
图11表示焊面为球心与电极帽本体异侧的环形球面，凹槽中间为弧形凸台、与焊面连接部分以弧面过渡的图1中A-A截面剖视图的一个实施例。
图12表示焊面为向上凸起的环形弧面，凹槽为球面的图1中A-A截面剖视图的一个实施例。
图13表示焊面为向上凸起的环形弧面，凹槽底部为平面、与焊面之间以弧面过渡的图1中A-A截面剖视图的一个实施例。
图14表示焊面为向上凸起的环形弧面，凹槽中间为弧形凸台、与焊面连接部分以弧面过渡的图1中A-A截面剖视图的一个实施例。
图15表示接触面中心具有凹槽，焊面上具有环形脊的一个电极帽的示意图。
图16表示图15中电极帽的焊面的区域放大图。
图17表示图15中B-B截面的剖视图局部的一个实施例。
图18表示图15中B-B截面的剖视图的另一个实施例。
图19表示两侧为直线、顶部为与两侧直线相切的圆弧的环形脊的横截面形状的一个实施例。
图20表示两侧为对称的曲线、顶部为与两侧曲线相切的圆弧的环形脊的横截面形状的一个实施例。
图21表示顶部和两侧都为直线的环形脊的横截面形状的一个实施例。
图22表示两侧为直线、顶部为与两侧直线相交的圆弧的环形脊的横截面形状的一个实施例。
图23表示两侧为不同的曲线、顶部为与两侧曲线相连接的曲线的环形脊的横截面形状的一个实施例。
图24表示两侧为对称的曲线、顶部为直线的环形脊的横截面形状的一个实施例。
图25表示一侧为直线、另一侧为曲线、顶部为曲线或直线的环形脊的横截面形状的一个实施例。
图26表示整个横截面为弧形的环形脊的横截面形状的一个实施例。
图27表示焊面31为环形平面，凹槽33为球面时环形脊位于焊面上的图15中B-B截面的剖视图的一个实施例。
图28表示焊面为环形平面，凹槽为球面时环形脊既位于焊面上又位于凹槽上的图15中B-B截面的剖视图的一个实施例。
图29表示焊面为环形平面，凹槽底部为平面、与焊面之间以弧面过渡时环形脊位于焊面上图15中B-B截面的剖视图的一个实施例。
图30表示焊面为环形平面，凹槽中间为弧形凸台、与焊面连接部分以弧面过渡时环形脊位于焊面上的图15中B-B截面的剖视图的一个实施例。
图31表示焊面为球心与电极帽本体同侧的环形球面，凹槽为球面时环形脊位于焊面上的图15中B-B截面的剖视图的一个实施例。
图32表示焊面为球心与电极帽本体同侧的环形球面，凹槽底部为平面、与焊面之间以弧面过渡时环形脊位于焊面上图15中B-B截面的剖视图的一个实施例。
图33表示焊面为球心与电极帽本体同侧的环形球面，凹槽中间为弧形凸台、与焊面连接部分以弧面过渡时环形脊位于焊面上的图15中B-B截面的剖视图的一个实施例。
图34表示焊面为向上凸起的环形弧面，凹槽为球面时环形脊既位于焊面上又位于凹槽上的图15中B-B截面的剖视图的一个实施例。
图35表示焊面为向上凸起的环形弧面，凹槽底部为平面、与焊面之间以弧面过渡时环形脊位于焊面上又位于凹槽上的图15中B-B截面的剖视图的一个实施例。
图36表示金属工件电阻点焊焊接时整体的总体侧视图。
图37表示本发明电极帽的焊面上未设置环形脊时使用本发明进行焊接时焊接初期的一个横截面示意图。
图38表示本发明电极帽的焊面上设置环形脊时使用本发明进行焊接时焊接初期的一个横截面示意图。
图39表示使用普通电极帽对2块2mm的5182-O铝合金进行电阻点焊后焊点处的截面形状。
图40表示在使用本发明实施例1中电极帽对2块2mm的5182-O铝合金进行电阻点焊后焊点处的截面形状。
附图标记，1-电极帽本体、11-电极安装通道、12-电极帽本体圆周、2-侧面、3-接触面、31-焊面、32-圆周、4-环形脊、41-实施例2中的一个环形脊、42-实施例2中的另一环形脊、43-沟槽、44-环形脊横截面、45-位于环形脊41侧面上的点、46-位于环形脊42侧面上的点、5-焊枪、51-第一焊枪臂、52-第二焊枪臂、53-第一焊接电极帽、54-第二焊接电极帽、6，7-焊接工件、8-焊接工件6和7焊接熔核区、9-熔核、d 1-圆周12的直径、d 2-圆周32的直径、d 3-凹槽为球面时，其外径尺寸、d 4-相邻两个环形脊之间的间距、d 5-环形脊的宽度、h-凹槽的深度、H-环形脊凸起的高度。
具体实施方式
本发明人经过广泛而深入的研究，通过大量试验，发现了一种接触面上中心具有凹槽的电极帽可以解决铝合金电阻点焊需要较大焊接电流，焊接飞溅严重而焊接强度相对较低，电极寿命低等问题，在此基础上完成了本发明。
下面结合具体实施例，进一步阐述本发明。应理解，这些实施例仅用于说明本发明而不用于限制本发明的范围。此外，附图为示意图，因此本发明装置和设备的并不受所述示意图的尺寸或比例限制。
需要说明的是，在本专利的权利要求和说明书中，诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。
实施例1
如图1-2所示，本实施例的电阻点焊电极帽包括大致呈圆柱状的电极帽本体1、电极与焊接金属材料的接触面3。本体1的一端处具有电极安装通道11，另一端具有圆周12。接触面3包括焊面31、圆周32、凹槽33。所述凹槽33位于接触面3的中心区域。所述电极帽还包括侧面2，侧面2为本体1的圆周12过渡到接触面3的圆周32的过渡区域，侧面2的形状为弧面，需要说明的是侧面2还可以为圆锥。当侧面2为弧面时，弧面的曲率半径大于等于电极帽本体1的圆周半径；当侧面2为锥面时，锥面的倾角为0-90°优选地，10-80°。侧面2的上表面为与凹槽相接触的部位，下表面为与本体1相接触的部位。需要说明的是，当圆周12的直径与圆周32的直径相同时，侧面2就成为电极帽本体1的一部分。此处需要 说明的是圆周12的直径即为电极帽本体1的直径，圆周12的半径为电极帽本体1的半径。侧面2也可以为其他一些适当的形状。
所述本体1的一端指的是电阻点焊时与电阻点焊机相连的一端，另一端指的是靠近焊接工件接触面的一端。
在另一优选例中，电极安装通道11的形状为圆台或圆柱形，电极安装通道11的形状也可以为其他一些适当的形状。
所述圆周32与圆周12是平行的，圆周32可以理解为是圆周12沿着垂直于本体1的轴线向上平移后直径大小改变了的圆周，圆周32的圆心与圆周12的圆心的连线与本体1的轴线重合，圆周32的直径d 2小于等于圆周12的直径d 1。
凹槽33可以理解为在接触面3的中间位置挖了一个一定形状孔且此孔向下延伸一定的距离，所述凹槽33的形状为弧面，或中间为平面、与环形焊面31接触部分为弧面，或中间为弧形凸台，与焊面31接触部分为弧面。凹槽33的深度为0.1-2mm；优选地，0.1-1.2mm。此处所指的凹槽33的深度是，凹槽33上部与焊面31相接触的边缘所在的平面到凹槽33最底部所在平面的垂直距离。
在另一优选例中，凹槽33的形状为球面，当凹槽33的形状为球面时，其外径d 3为2-15mm；优选地，4-12mm。
所述焊面31为环形平面或为球心与电极帽本体同侧的环形球面或为球心与电极帽本体异侧的环形球面或向上凸起的环形弧面。
所述球心与电极帽本体同侧及球心与电极帽本体不同侧指的是以焊面31为临界面，球心向电极帽本体1靠近的方向为与电极帽本体同侧的方向，球心远离电极帽本体1的方向为与电极帽本体异侧的方向。
当焊面31为环形平面时，其外径范围即圆周32的直径为2-30mm，优选地，5-20mm；当焊面31为环形球面时，焊面31所在的球的半径为10-100mm；当焊面31为向上凸起的环形弧面时，弧的曲率半径为1-10mm，弧面最高点与最低点所在平面的垂直距离为0.1-5mm。
图3-14显示了焊面31和凹槽33的形状相组合时，图1中A-A截面剖视图的各个实施例。图1中A-A截面剖视图的可以为焊面为环形平面，凹槽为球面(图3)或焊面为环形平面，凹槽底部为平面、与焊面之间以弧面过渡(图4)或焊面为环形平面，凹槽中间为弧形凸台、与焊面连接部分以弧面过渡(图5)或焊面为球心与电极帽本体同侧的环形球面，凹槽为球面(图6)或焊面为球心与电极帽本体同侧的环形球面，凹槽底部为平面、与焊面之间以弧面过渡(图7)或焊面为球心与电极帽本体同侧的环形球面，凹槽中间为弧形凸台、与焊面 连接部分以弧面过渡(图8)或焊面为球心与电极帽本体异侧的环形球面，凹槽为球面(图9)或焊面为球心与电极帽本体异侧的环形球面，凹槽底部为平面、与焊面之间以弧面过渡(图10)或焊面为球心与电极帽本体异侧的环形球面，凹槽中间为弧形凸台、与焊面连接部分以弧面过渡(图11)或焊面为向上凸起的环形弧面，凹槽为球面(图12)或焊面为向上凸起的环形弧面，凹槽底部为平面、与焊面之间以弧面过渡(图13)或焊面为向上凸起的环形弧面，凹槽中间为弧形凸台、与焊面连接部分以弧面过渡(图14)的形状。
值得注意的是，本发明中的电极帽可以由任何导电和导热材料制成，例如可由铜合金制成，包括铜铬(CuCr)合金、铜铬锆(CuCrZr)合金，添加氧化铝颗粒的铜合金或其他各种的可用作电极材料的铜合金；上述所说铝合金可包含变形铝合金或铸造铝合金，包括表面具有涂层或未涂层的铝合金基板，例如铝镁合金、铝硅合金、铝镁硅合金、铝锌合金、铝铜合金等铝合金。而且其材料状态可以包括各种回火，包括退火、应变强化、固溶强化等状态。铝基板的厚度一般为0.3毫米至6.0毫米之间，优选地为从0.5毫米至3.0毫米之间。
实施例2
本实施例的电阻点焊电极帽与实施例1类似，与之不同的是本实施例焊面31或凹槽33上具有凸起的环形脊4，如图15-16所示，相邻的两个环形脊之间形成一沟槽43。所述环形脊4可以理解为横截面44为一定结构的平面围绕电极帽的中心轴旋转一周所形成的环状结构，其中横截面44的下部与焊面31相接触，且整个横截面44与焊面31相垂直。所述电极帽的中心轴为经过圆周12的圆心并垂直于圆周12的直线。需要注意的是所述环形脊的数量不限于2个，根据需要可以为1个或多个。
如图17-18，所述凸起的环形脊4在焊面31上有如图17和18两种凸起方式，所述环形脊4相对于焊面31凸起的高度H可以为20-500um。此处所说的凸起的高度指的是环形脊4在垂直于焊面31或凹槽表面的方向上，环形脊下部到顶部的垂直距离H。两个相邻的环形脊之间间隔所形成的沟槽43的宽度d 4即两个环形脊之间的距离为50-3000um。此处所说的相邻两个环形脊之间的沟槽43的宽度d 4指的是当带有环形脊的电极帽的局部剖视图如图17所示时，分别位于两个相邻环形脊41、42上的两个点45与46之间的距离，点45与点46位于环形脊41与42相邻的两个侧面上，两个点之间的连线平行于焊面31。环形脊的宽度d 5可以为200-3000μm，或更优选地为500-2000μm。此处所说的环形脊的宽度d 5指的是位于同一个环形脊的两个侧面上的两个点之间的距离，所述两个点位于环形脊的同一横截面上。需要说明的是当环形脊的数量为3个以上时，相邻两个环形脊之间的沟槽宽度d 4可以相同也可以不同， 各个环形脊的宽度d 5可以相同也可以不同。
如图19-26所示，显示了环形脊横截面44可能的形状结构(a表示横截面的下部，b表示横截面的顶部，c表示横截面的两侧)，横截面44的形状可以为两侧为直线、顶部为与两侧直线相切的圆弧(图19)或两侧为对称的曲线、顶部为与两侧曲线相切的圆弧(图20)或顶部和两侧都为直线(图21)或两侧为直线、顶部为与两侧直线相交的圆弧(图22)或两侧为不同的曲线、顶部为与两侧曲线相连接的曲线(图23)或两侧为对称的曲线、顶部为直线(图24)或一侧为直线、另一侧为曲线、顶部为曲线或直线(图25)或整个横截面为半圆形(图26)的结构。需要注意的是上述所阐述的环形脊的横截面结构只是优选的一些结构，也可以为其他一些适合环形脊截面形状的结构。
如图27-35，显示了焊面31和凹槽33的形状不同时，环形脊位于焊面31和凹槽33的位置情况，需要说明的是图中只是列举了一些环形脊在焊面和凹槽上的一些优选位置，环形脊可以单独位于焊面31上或可以单独位于凹槽33上或同时位于焊面31和凹槽33上，并且位于焊面31和凹槽33上的环形脊的数量可以根据使用情况随机选择。
实施例3
本实施例揭示了采用本发明电极帽焊接铝合金工件的装置及过程，如图36所示，5为可用于电阻点焊连接第一铝合金工件6和第二铝合金工件7的焊接位置8处的焊枪，焊枪5包括第一焊枪臂51、第二焊枪臂52、第一焊接电极帽53和第二焊接电极帽54。第一和第二铝合金工件6、7由比如铝镁合金、铝硅合金、铝镁硅合金或铝铜合金等铝合金构成，铝合金工件的厚度为0.5-3mm。更佳地，铝合金工件可以为2.0mm厚的5182-O铝合金。焊接时铝合金工件可以为2个(比如只有6和7)也可以为2个以上的组合，且各个铝合金工件的厚度可以相同也可以不同。需要说明的是，本文中所使用的术语“工件”是指广泛地包含金属片层、突起部、铸件和可电阻点焊的其他铝合金件或钢材、镁合金工件。焊枪臂51、52通常是具有较大自动化焊接操作中的一部分，一般包括C型、X型和其他种类的结构形状，通常是由机器人或自动化部件来实现的，在本领域中是很好理解的。
第一和第二焊枪臂51和52上具有安装的如实施例1和2所述的第一和第二焊接电极帽53和54，在点焊时，焊枪臂被操作以使电极帽53和54可以精密贴靠工件6和7，通过焊枪臂和电极帽传导压力和电流，使工件6、7贴合部位8熔化并形成点焊接头。两电极帽53和54可以为实施例1和2所述的各种结构，53和54的结构可以相同也可以不同。
图37表示在使用本发明实施例1中电极帽进行焊接时焊接初期的一个横截面示意图。电极53和54具有相同的结构尺寸，焊接时焊枪通过焊面31传递压力和电流，两层金属材料6和7相接触部分受到环形电极作用的区域会产生电阻热，从而形成熔核9，进而形成环形熔 池。两层金属工件外侧首先接触，相接触部分受到环形电极作用的区域会产生电阻热、形成环形熔池，随着焊接时间的延长，并中心区域的逐渐接触，环形熔池在热传导作用下向中心生长，由于与凹槽相对应的两金属工件中心区域面积(焊点内侧)较小并且未与电极帽接触，热量集中于外侧，随着接触区域金属材料的熔化和塑性变形，其会向电极中心凹陷处挤压扩展，进而中心新的接触面又产生，电阻热在新的接触面产生，导致环形熔池向环形中心生长，进而使与凹槽相对应的两金属材料接触部分形成熔核，完成焊接。由于凹槽的存在本发明的电极帽初期与金属工件的接触面积减小，整体产热集中、散热变慢，并随着焊接的进行，接触面积变大散热变快，所以与普通电极帽相比形成相同大小的焊点所需要的焊接电流会降低，节省电力成本，并提高电极寿命；另外，因为环形熔池首先形成，中心凹槽的存在，会使环形熔池由外向内生长，与普通电极帽熔池从内向外生长相反，塑性金属材料会在压力及电流作用下被挤向电极中心凹槽区域，有利于避免在焊点边缘产生气孔及飞溅，从而能够增大熔核直径、提高焊点强度。
环形脊存在的情况下，在接触时，环形脊可以刺破铝合金表面的氧化膜，进而降低接触电阻，并且可以增大接触面积，增强散热，从而减小电极焊接面与铝合金板接触面的热量，从而提高电极的使用寿命。
图38表示在使用本发明实施例2中电极帽进行焊接时焊接初期的一个横截面示意图。焊接原理与图37的焊接原理类似。
实施例4
如图39所示为使用普通的电极帽对两块厚度为2mm的5182-O铝合金进行电阻点焊后，焊点处截面形状；由图中可看出其熔核直径较小只有6.08mm，且内部存在明显的缩孔缺陷，飞溅严重，边缘焊接变形较大，这就造成了其焊点强度较低。
实施例5
如图40所示为使用本发明实施例1中的电极帽并采用实施例3的焊接装置及焊接原理，对两块厚度为2mm的5182-O铝合金进行电阻点焊后，两块铝合金焊点处的截面形状；由图中可看出其熔核直径达到了8.23mm，且内部无明显的焊接缺陷，没有飞溅产生，焊点边缘无明显的变形，这就大大提高了其焊点强度。
尽管本发明已以较佳实施例揭露如上，然而并非用以限制本发明，任何熟悉本领域的技术人员，在不脱离本发明的精神和范围内，做出的种种的等效的变化或替换，均属于本发明保护的范围。因此，本发明的保护范围当视后附的本申请权利要求所界定的范围为准。

Claims (10)

  1. 一种电阻点焊电极帽，包括：
    呈圆柱状的电极帽本体(1)；
    具有焊面(31)、圆周(32)、凹槽(33)的接触面(3)，凹槽(33)位于接触面(3)的中心，其上部边缘与焊面(31)相连接，圆周(32)为焊面(31)的外径；
    侧面(2)，侧面(2)为电极帽本体(1)到接触面(3)的过渡区域，侧面(2)的形状为弧面或锥面；
    侧面(2)的上下表面分别与接触面(3)及电极帽本体(1)的另一端以弧面或倒角的形式相连接。
  2. 如权利要求1所述的电阻点焊电极帽，其特征在于：凹槽(33)的形状为整体为一弧面，或底部为平面、与焊面(31)连接部分以弧面或锥面过渡，或中间为弧形凸台、与焊面(31)连接部分以弧面或锥面过渡。
  3. 如权利要求1或3所述的电阻点焊电极帽，其特征在于：凹槽(33)的深度h为0.1-2mm。
  4. 如权利要求1或3所述的电阻点焊电极帽，其特征在于：当凹槽(33)整体为一弧面时，凹槽(33)弧面的曲率半径为1-50mm；当凹槽底部为平面时，平面是半径为0.1-10mm的圆。
  5. 如权利要求1所述的电阻点焊电极帽，其特征在于：焊面(31)为环形平面，或为球心与电极帽本体同侧的环形球面，或为球心与电极帽本体异侧的环形球面，或为向上凸起的环形弧面。
  6. 如权利要求1所述的电阻点焊电极帽，其特征在于：还包括位于焊面(31)或凹槽(33)上环形脊(4)，环形脊(4)的截面形状为直线或曲线或直线与曲线的组合。
  7. 如权利要求1所述的电阻点焊电极帽，其特征在于：还包括相邻两个环形脊(4)之间形成的沟槽(43)。
  8. 如权利要求7所述的电阻点焊电极帽，其特征在于：环形脊(4)凸起高度H为20-500um。
  9. 如权利要求7所述的电阻点焊电极帽，其特征在于：环形脊(4)的数量为0-5个。
  10. 如权利要求7所述的电阻点焊电极帽，其特征在于：相邻两个环形脊(4)之间的间距为50-3000um。
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