JP2006320959A - Welding electrode and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding electrode and a method capable of preventing any crack or a space from being formed in a coating or delaying formation thereof when the coating is formed on the welding electrode. <P>SOLUTION: The welding electrode has a body having a shank and a contact region for placement against a workpiece during the welding. A portion of the body may be formed on a parabolic profile. A coating is formed on the contact region. The coating may have a first layer, and a second layer formed over the first layer. The first and second layers may have different compositions. The electrode may have an internally formed cooling finwork for interaction with a liquid cooling system. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to the field of welding electrodes.

  The welding electrode can be used for electric resistance welding. Resistance welding techniques are widely used in the industry, an example being spot welding of automobile bodies. In this particular application, a welding gun fitted with a pair of cooperating welding electrodes is moved step by step along the welding path. At each stage, a pair of welding electrodes are brought close to the workpiece to be welded and a current flows between them. The electrical resistance at the boundary between the workpieces causes local overheating so that the workpiece melts locally to form a weld nugget. Thereafter, the electrode is removed from the workpiece. On a production line basis, these steps are performed as a fast procedure and repeated at each successive welding position.

US Pat. No. 4,734,254 US Pat. No. 4,423,617

  When manufacturing in large quantities, especially when welding using robots, it is advantageous to be able to operate with little interruption. One reason for the interruption is that the electrodes need to be changed from time to time. In general, it is desirable to be able to maintain a reasonable weld quality without excessively frequent electrode changes.

  The electrodes are most commonly made of copper or a copper alloy, which has a relatively small electrical resistance and allows a relatively high current to flow between the electrodes. As expected, this electrode is prone to heat during use. As the temperature increases, there are a number of phenomena associated with it that shorten the life of the electrodes and / or reduce welding performance. First, the electrode may catch the workpiece, i.e., the electrode may stick to the workpiece, resulting in sparks and weld cracks when the electrode is removed.

  Secondly, the increase in temperature softens the copper electrode, thereby making it easier to deform under the pressure of contact during welding. Such deformation includes plastic flow of the electrode tip (tip), which tends to make the tip flat or stubborn, and also tends to increase the contact area of the welding tip. This phenomenon is called “mash roaming”. Increased contact area tends to result in lower temperature welds (due to reduced current density), possibly incomplete welds, higher weld currents, or combinations thereof.

  Thirdly, since this welding electrode is frequently used for spot welding a zinc iron plate in automobile manufacture, zinc easily moves from the zinc iron plate to the copper of the welding electrode at the welding temperature. This tends to be greatest at the electrode contact area. This undesirably forms a brass alloy with the electrode tips and tends to shorten the life of the tips.

  In general, it is desirable to maintain the electrode tip at a low temperature or to prevent interaction between the electrode tip material and the material or coating to be welded. It is desirable to form a coating on the electrode tip to prevent zinc migration and to prevent plastic deformation. These coatings can be relatively thin films, one reference being about one thousandth or one thousandth of an inch in the case of a titanium carbide coating, and another reference being a ceramic coating. In the case of things, 5000 angstroms have been proposed. When the coating is formed on the electrode tip, the life of the electrode tends to be extended if there is almost no opening or defect in which zinc can move in the coating, and according to the present inventor, the coating It is desirable to prevent or delay the formation of cracks or gaps. Over time, electrode tip coatings are prone to degradation as a result of heating and chemical environments as a result of impact when the welding head is brought closer to the workpiece. The coating wears out or cracks and the electrode approaches the end of its useful life. The inventor of the present application generally indicates that the longer the time during which a certain coating or all the coatings are on the electrode tip, and the greater the proportion of the portion of the electrode tip that is still covered, the longer the service life of the electrode. thinking.

  In an aspect of the invention, the welding electrode has a hollow body. This welding electrode is mainly made of a copper-based material. The welding electrode has a first end for engaging the electrode holder. The first end has a first end having an opening for supplying coolant to the hollow body and for discharging from the hollow body. The welding electrode has a second end with a welding tip for engaging the object to be welded. The hollow body provides an array of chambers formed therein. This chamber extends from the opening toward the welding tip. The welding electrode has a web formed therein between a pair of adjacent chambers.

  In a feature of an embodiment of the invention, the electrode has a primarily titanium coating thereon. In other features, the coating has a first layer and a second layer. In other features, the first and second layers are primarily composed of titanium carbide, and the second layer includes a higher weight percentage of titanium carbide than the first layer. In other features, the first layer includes a higher weight percentage of titanium carbide than the second layer. In other features, the welding electrode has a hollow shaft that allows the coolant to be introduced therein. The electrode has cooling fins therein. In other features, at least a portion of the electrode is formed of a copper dispersion strengthened alloy. In yet another feature, the second layer is composed of a material that has better adhesion to copper than the first layer.

  In other features of embodiments of the present invention, the first layer is formed by depositing a material that is primarily nickel on a weld cap body material that is primarily copper. In other features, the first layer is an underlayer formed of a material that is at least 5% by weight molybdenum deposited primarily on a copper weld cap body. In other features, the first layer is an underlayer formed of a material that is at least 5 wt.% Tungsten deposited primarily on a copper weld cap body. In still another feature, the body is mainly made of copper, and the covering includes any one of (a) an overlying layer and (b) a base layer in which molybdenum and tungsten are mixed, and the molybdenum and tungsten layers. The mixture is part of the coating material that is applied to the weld cap body, and the welding electrode comprises 10-15% by weight of the molybdenum and tungsten together.

  In another aspect of the present invention, a method for manufacturing a welding electrode is provided. This method is a molded blank made primarily of copper material, a shaft for fixing to an electrode holder, and a head having a contact area for placement against the workpiece to be welded. The process of preparing the shaping | molding blank which has these. The method includes a step of forming a main hole in the shaft portion, and a step of forming a plurality of sub chambers in the head, the sub chambers communicating with the main hole by liquid.

  In other features, the obtaining step includes obtaining a blank having internal fins formed therein. In yet another feature, prior to the step of forming the first layer, a step of cleaning the contact area is performed. In still other features, the cleaning step includes a mechanical cleaning step. The mechanical cleaning step is a shot peening step at least in the contact region. In other features, forming the first layer includes using a first deposition process, forming the second layer includes a second deposition process, and the first deposition process is different from the second deposition process.

  In other features, the method includes forming a central internal cross. In still other features, the method includes forming a blank to have a head positioned axially forward of the shank, wherein the head is primarily (i) parabolic and ( ii) providing a shape formed along a curve that is one of the elliptic curves. In other features, the curve has a vertex at the forefront position of the head, and the method includes removing the vertex to produce a flat end face of the head.

  The foregoing and other aspects and features of the present invention can be understood by the following detailed description of the invention and the accompanying drawings.

  The following description and the embodiments described therein are illustrative or specific embodiments of the principles of aspects of the present invention. These examples are provided for purposes of illustration and are not intended to limit their principles and the invention. In the description, the same parts bear the same reference numerals in the specification and the drawings. The drawings are not necessarily of the same dimensions, and in certain instances, ratios may be exaggerated to more clearly represent features of the present invention.

  In this specification, as will be shown below, the welding electrode is either male or female. In any case, the welding electrode can have the form of a rotating body formed about an axis. The rotating body has a long axis, that is, an axial direction called a z-axis, a radial direction extending from the z-axis or a radial axis r, and a circumferential direction represented by angle data perpendicular to the axial direction and the radial direction. It is possible to study in a pole-cylinder coordinate system having

  Consider the example of a male electrode shown in FIGS. 1a and 1b. In this example, the electrode 20 is mounted on an electrode holder 22 (shown in phantom in FIG. 1b). The electrode holder 22 includes a coolant supply conduit 24 (shown in perspective), which is like an internal passage for coolant such as water. The electrode holder 22 also includes a coolant return passage 26 (shown in perspective) that draws coolant out of the electrode 20.

  With respect to form, the welding electrode 20 has a body 30. The body 30 has two essential regions, a head shown generally as 32 and a shank shown generally as. The shank 34 has an outer surface 36 that has a frustoconical cross section when the shank 34 has an external taper indicated by an angle α. In this cone, a narrow end 38 extends from the head 32 and a wider end 40 bounds by a shoulder 42. The taper of the shaft portion 34 is intended to facilitate the shaft portion 34 being taken into a receiving port of a welding electrode holder such as the holder 22, and is easy to pack in the holder, and is firmly connected to the receiving port of the electrode holder. Can be attached. Thereby, it is possible to obtain a contact surface suitable for transmitting a current.

  The shoulder 42 extends in a plane that is substantially perpendicular to the major or central axis, i.e. the axis of rotation indicated by CL, whereby the shoulder 42 has an annular shape. The shoulder 42 has an axially rearward surface 44 called a joint or a joint surface, which serves as a current path when in use.

  The shaft portion 34 can be hollow. For example, the shaft portion 34 has a cavity or chamber formed therein, and this cavity is specified as a hole 46 extending from the distal end 38 toward the inside in the axial direction. The hole 46 is cylindrical or is formed, for example, by a punch and has a small taper to facilitate removal of the part from the punch or die. The hole 46 is a hole that has not been removed, extends beyond the shoulder 42 in the axial direction, and terminates in a hole end region 48 where most of the body 30 is entered. The hole end region 48 is narrow to some extent and can include a narrowed region 49. The narrowed region 49 can be a tapered portion, which need not necessarily be a circular tapered portion. For example, the narrowed region 49 may have a shape with a round protrusion when viewed from one end as shown in FIG. This form of rounded protrusions has an array of tapered protrusions 50 that are arranged as protrusions 51, 52, 53, 54 around the center line of the longitudinal axis. End region 48 also has a conventional heat transfer device, such as a fin mechanism, which includes one or more fins. In one embodiment, fin mechanism 56 includes a centrally located fin 58. The fin 58 has a shape of a prefix cone, which extends from a generally wide bottom surface to a narrow tip 59. The fin 58 has a tapered circular cross section. The fins 58 tend to be relatively bulky. The ratio of height to bottom width (in this example, diameter) ranges from less than 2: 1, may be less than 1: 1, and in one embodiment is less than 2: 3. The hole end region 48 terminates at the end wall 62. This end wall extends around the wider end of the fin 58 and more generally connects to the narrowing wall 47 of the tapered protrusion around the hole end region 48. Wall 55 is the foremost end of hole 46. It is considered that when the end of the water reservoir is relatively close to the welded joint, a short conduction path to the surface where heat conduction to the liquid cooling medium is relatively fast is likely to be formed. Therefore, aggressive liquid cooling inside the water reservoir can prevent or delay the annealing of the copper base alloy of the weld cap in the tip region. Thereby, the life of the welding cap can be extended. Also, the relatively bulky center fin is more compatible with cold formation than the long, thin fins or arrayed fins.

  The head portion 32 can have a chip region 60 and a side region 62 extending from the region toward the rear in the axial direction. The surface of the side region 62 also extends radially outward and rearward relative to the tip region 60 and extends rearwardly on the arcuate portion 64. In the cross section, this arcuate part is formed in a part of a parabola or elliptic curve. The tip region 60 is a parabolic or oval cut and becomes flat. The head portion 32 is initially formed in a completely parabolic or elliptical shape. The final contact shape is created by finishing the chip region 60. For example, the head portion 32 may initially include an end portion 61 that is a parabolic or elliptical end. During the finishing process, the end 61 is partially removed to provide a flat prefix shape or other suitable shape as shown at 60. The side region 62 includes or enters a barrel-like base region 66, which has a substantially constant radius and the shoulder 42 is distal.

The hole 46 and the region 48 of the hole 46 are portions called water reservoirs. The dimension of the representative width from end to end of the cap 20 is taken as the outer diameter φ, which is measured across the cap 20 in front of the shoulder 42. The other dimension δ ₁ is taken from the far point of the parabola or elliptic curve at 61 of the electrode to the position of the wall 55 at the foremost end of the puddle. Still another dimension δ ₂ is taken from the far point of the parabola or elliptic curve to the surface of the shoulder 42. The third dimension δ ₃ is taken from the finished surface indicated at 60 to the nearest portion of the sump in the end wall 62. In one embodiment, the ratio φ: δ ₁ between the representative cross-sectional dimension and the first dimension is taken. This ratio can be greater than 2: 1, and in some examples can be greater than about 5: 2. As another ratio, a ratio between the first distance δ ₁ and the second distance δ ₂ is taken. In one embodiment, this ratio can be 2/5 or less, and can be in the range of about 0.3 to about 0.5. Alternatively, the third ratio can be taken between the difference between the first and second distances (where δ ₄ = δ ₂ −δ ₁ ). This ratio can be in the range of 5:12 to 2: 3. The parabolic or oval shape reduces plastic deformation at the end of the weld cap compared to a mold recommended by ISO 5821 or the Resistance Welding Manufacturers Association (RWMA) with a “bullet” rounded design. There seems to be a tendency to not cause or delay.

  In one embodiment, the end wall 55 does not intersect the longitudinal centerline, but rather has a shape that connects protrusions extending around the longitudinal centerline CL of the cap 20, such as a ring or ring. Form a surface.

  Referring to FIG. 3, the chip region 60 can have a coating 70 formed thereon as described below. In some cases, the body 30 is made from substantially pure copper or a copper-based alloy and has a relatively high thermal conductivity (possibly greater than 200 W / mK). One alloy is an alloy composed primarily of three elements: copper, chromium and zirconium (CuCrZr). Other alloys are primarily binary alloys such as copper and zirconium (CuZr) or copper and chromium (CuCr). Copper and Berrylium (CuBe), copper tungsten (CuW) and copper alumina (Cu-A1203) alloys are also possible as alternative coating materials. One copper alloy with silver is suggested in US Pat. As another alloy, there is a dispersion strengthened alloy described in Patent Document 2 issued to Nippon on January 3, 1984. This dispersion strengthened alloy can be included in only one part of the welding electrode 20 forming the tip.

  The welding electrode 20 (or 120 or 170 described below) can be manufactured in many ways, such as solid machining, casting or forging. About the formation of the lump of copper solid (or copper alloy depending on the case), it can manufacture by the substantially the same method as described in patent document 2, for example. However, the central portion of the shaft portion may be formed by the process of a male die, that is, a die having an external shape corresponding to the shape of the longitudinal groove described above, and having a cavity for defining heat transfer ribs or fins. it can.

  Manufacturing the welding electrode 20 (or electrode 120 or 170 as described below) can include applying a coating 70 to the contact area at the electrode tip 60. The coating 70 can include a first surface coating layer, material or composite, which is designated by the numeral 80 and is generally indicated. In addition, this layer is entirely or partially overlapped with the second surface covering layer, substance or composite 82.

  The step of applying the end covering 70 to the tip 60 of the welding electrode 20 is performed first by removing impurities from the end region 60. The end region can include a flattened or scraped end surface, such as surface 60, and can include a portion or all of the portion adjacent to the tapered side region 62. Removing the impurities can include removing oxides, dirt, oil, or all of them. As an alternative, or in addition, there may be a work step that hardens the end region. The step of removing impurities and the step of curing operation can be performed in the same process at the same time, and can also include bringing compressive internal stress into the contact area. The step of the curing operation may include a shot peening step for the end region. The shot peening process makes it easier to remove surface impurities and maintain the surface to which the surface coating is applied in a relatively new and clean state. The shot used for shot peening can be made of non-participating materials such as glass beads (ie, materials that do not substantially react with copper). In one embodiment, a gas such as, for example, compressed air in the range of 30-50 psig directs No. 7 glass beads to the uncoated end of the electrode for a time in the range of 15 seconds to 1 minute. Used for In one embodiment, this time is approximately 30 seconds.

  The first portion, region, or layer 80 can be formed with a different composition than the layer 82 overlying it. In turn, this layer 82 is different from the composition of layer 84 (if such a third layer is present), and this layer 84 can be different from any composition of further layers. In some cases, although the composition of the powder or solid rod that is the material from which the coating is made is known before the coating process begins, the very process of layer formation or deposition results in local melting and alloying. You can make it. As such, the layers are smeared or smeared or prone to flow into each other, so that the composition of the various layers does not change clearly or clearly and still changes in the concentration of one composition or other layer organisms Is.

  The first layer, region, or base coating is relatively rich in certain materials over other layers. For example, the first layer can include a relatively higher concentration of nickel or nickel alloy than can be included in one or more subsequent layers. Alternatively or additionally, the layer closest to or relatively close to the copper (or primarily copper) body of the weld cap has a relatively higher concentration of molybdenum, tungsten than the subsequent layer or layers. , Or both. Alloys with relatively higher amounts of relatively softer metals, such as nickel and molybdenum-tungsten alloys, tend to have an affinity for copper and are also relatively hard, primarily titanium or titanium carbide layers I.e., when overlaying the coating layers, it is possible to avoid porosity, cavities and surface cracks, which are the alloys of these (which can be applied in one or more subsequent layers) Is believed to be easier than when layered without the mediating effect of base coatings of different composition. Softer metal or metal alloy layers also allow thermal expansion. That is, it is considered to act as a moderating or moderating effect on the thermal expansion between the underlying copper (or copper alloy) and the layer of titanium, titanium carbide, or primarily bi-bore titanium. It is done. In addition, these intervening, softer layers are believed to help the overall coating of the titanium, titanium carbide, or titanium alloy alloy to adhere generally to the predominantly copper substrate of the weld cap. In other words, this lower layer, in effect, acts as an intermediate adhesive layer between the underlying copper-based substrate and a layer or layers of titanium base that are more rigidly layered on top. There is a tendency to fulfill. In one embodiment, the powder or sintered material deposited to make the first layer or layers is in the range of 8-40 wt% nickel, or narrower 10 wt% and 35 wt%. Nickel may be included in the range between. Alternatively, 25-35 wt% nickel can be included. Other layers may contain 10-20% by weight nickel.

  Alternatively or additionally, the powder or sintered bar material contains 3-20% by weight molybdenum prior to deposition. Other embodiments may include 10-15 wt% molybdenum, and yet other embodiments may include 4-8 wt% molybdenum. Alternatively or additionally, tungsten may be included between approximately 0.65% and 2.0% by weight. Other layers may contain approximately 0.8 to 1.1% tungsten. Still other layers may contain approximately 1.2 to 1.8% tungsten. The sum of molybdenum and tungsten can range from about 5% to about 17% by weight. In one embodiment, the sum of molybdenum and tungsten in the pre-deposition powder or sintered rod material is approximately 5 to 8% by weight. In other layers, the sum of molybdenum and tungsten is approximately 12 to 17% by weight.

The subsequent layer or layers of the coating is relatively rich in titanium or a titanium alloy such as titanium carbide, in which several such layers are deposited, but in the subsequent layers Titanium or titanium alloys can be made increasingly rich. Examples of the titanium alloy are titanium carbide (TiC) and diborotitanium (TiB ₂ ). Such a layer or layers tend to be harder than the previously deposited layer or layers rich in nickel, molybdenum or tungsten. A layer of titanium, titanium carbide or titanium biborate can be made from a powder or bar with an initial concentration between 60 and 80 wt% titanium by weight. Such powders also contain 10-35 wt% nickel, or in one embodiment 13-17 wt%, and in another embodiment 28-35 wt% nickel.

  The finish or coating layer or layers thereof again contain relatively more nickel, molybdenum or tungsten, or molybdenum and tungsten contents, compared to the layer of mainly titanium, titanium carbide or bi-bore titanium material. Can do. This overlying layer tends to fill cracks or discontinuities in the underlying titanium carbide or bi-bore titanium layer. Such relatively rich molybdenum or tungsten layers are believed to tend to prevent zinc from moving into their cracks and discontinuities. That is, where there is a layer that is relatively hard and has cracks, gaps, or other defects in the same layer of material deposited as a coating, such as a titanium-based layer or a coating of titanium carbide or titanium carbide In some embodiments, an overlayer is applied to block or cover these defects, thereby preventing molten zinc from moving therethrough. The overlay layer can include a material that has a higher viscosity than a titanium-based layer and that has a higher melting point than zinc. In one embodiment, the material may be or include molybdenum. In other embodiments, the material may be or include nickel. The overlayer can also contain a tungsten component.

  In one embodiment, a layer comprising primarily titanium carbide is applied to the copper substrate and a relatively molybdenum and tungsten rich layer is applied as a layer over the titanium carbide. When applied, the material melts, and the material tends to mix in the remelted state. After deposition has been performed on the finished electrode surface, the resulting coated areas are approximately 40-50 wt% titanium, 10-30 wt% nickel, and 20-40 wt% copper. The initial powder or sintered bar used to make this coating is 70 to 80 wt% titanium carbide, 10 to 15 wt% nickel, and 10 to 15 wt% molybdenum. In some examples, powders are used for laser coating processes, whereas sintered bars can be used for discharge deposition.

  As stated, the various layers can be applied by electrical discharge deposition or laser coating. When discharge deposition is used, the current is 60 Hz a. c. It is. Alternatively, a variable direct current such as a pulse DC or a half-rectified AC may be used. In some cases, in some embodiments in which current is used, the current can vary at frequencies greater than 100 Hz. In some examples, the frequency is greater than 1000 Hz, and in some examples the leaf frequency is in the range of 5000 Hz to 50,000 Hz. In one embodiment, the frequency used is 10,000 or 20,000 Hz, (+/− 25%).

  In one application, the overall single coating layer is approximately 50% titanium, 20% nickel, and 25% copper (by weight) at the surface, and the two coating layers are approximately 40% titanium. 40% nickel and 15% copper, and the three coating layers are approximately 15% titanium, 70% nickel and 15% copper. (The ratio can vary by 10% or more depending on where and how the measurement is made. For example, the ratio of titanium tends to be higher at the center of the layers to be stacked.)

  The welding electrode 20 of FIGS. La and 1b is referred to as a male electrode, whereas FIGS. 4a, 4b and 4c show a female welding electrode 120. FIG. The female welding electrode 120 has a main body 130 having a head portion 132 and a shaft portion 134. In this example, the shaft portion 134 is an outer substantially round cylindrical skirt 136 and a tapered surface that faces mainly inward in the radial direction and has a mating socket or a driving shaft. A surface 138 adapted to be adapted to The taper of this surface is of a small angle such as the angle α. An internal hole 146 is formed in the shaft portion 134 and extends from the distal end 142 of the shaft portion 134 to the foremost end 144 that does not escape axially. The tapering taper ends at a first longitudinal position or shoulder 148, which is a portion of the range from the distal end 142 to the distal end 144. The male welding electrode base is identified as a holder. The foremost end of the holder contacts the shoulder 148. The foremost portion 149 of the internal hole 146 can have substantially the same internal shape as described above in the description of the cap 20, where similar elements are given the same numbers used above.

The head part 132 has a flat chip or chip region 160. Accordingly, the head portion is shaved and a flat tip is produced as shown in the examples of FIGS. La and 1b. That is to cut or finish the initial round tip 152. The round tip 152 is initially formed in a parabolic or elliptic curve shape as described above. As shown in the example of FIG. 1a, the head portion 132 has an arcuate side portion 153 and terminates in a substantially tangential direction in a circular cylindrical wall 154 facing outward in a substantially radial direction. To do. The axially innermost end of the hole 146 is an end wall 155 that is axially separated from the shoulder 148 by a distance δ ₅ . This distance is the depth of the water reservoir from the sloped cut to the end of the inner wall of the hole 146. The axial distance between the wall 155 and the tip 160 is similarly indicated as δ ₃ . As described above, δ ₃ can be made relatively small. That is, δ ₃ can be smaller than 2/3 of the total diameter Φ ₁ of the cap 120. In one embodiment, δ ₃ can be 1/2 or less of Φ ₁ , and in other embodiments, can be in the range of 3/8 to 1/2 of Φ ₁ , approximately 2 / 5Φ may be _one.

In an alternative representation, the reservoir in front of the shoulder 148 in the hole 146 is large compared to the total distance from the shoulder 148 to the tip 160 (or 152). That is, the ratio of the distance δ ₅ to the distance δ ₃ is in the range of 2: 3 to 1: 1, and may be in a narrower range of 3: 4 to 9:10, and in one embodiment is approximately 4 : 5. Also, in some cases, the main lateral diameter in the water reservoir 150 in front of the fin mechanism 56 is represented by the dimension Φ ₃ of the end wall 55, which is the main area of the tip region 160, shown as the tip diameter Φ _2. It can be larger than the dimensions. Some or all of the tips 160 can be provided with a coating 70 as described above with respect to the description of the welding electrode 20. The welding electrode 120 can be made of any of the materials described above with respect to the description of the welding electrode 20 and can be manufactured according to the processes described with respect to the description of the welding electrode 20.

  Yet another electrode is shown at 170 in FIG. 5a. The welding electrode 170 is generally similar to the welding electrode 120 and can include any type of outer coating described herein. The welding electrode 170 differs from the welding electrode 120 only in that the internal shape is round. Further, the welding electrode 170 may alternatively be shipped to the customer in an uncoated form and produced in an uncut form. This is to achieve the initial weld contact diameter, which varies from an unsharp tip to a medium or large flat part diameter. It is a matter of course that the welding electrode 170 can be made in the same type of female type as the welding electrode 120 or in the same type of male type as the welding electrode 20 by providing an appropriate shaft portion.

  The welding electrode 170 has a main body 172 having a head portion 174 and a shaft portion 176. The shaft portion 176 can be substantially the same as the shaft portion 134. The welding electrode 170 has an internal hole 178 formed inside the shaft portion 176. The hole 178 extends axially from the distal end 142 of the shank 176 to the foremost dead end, ie, end 180. The tapered taper ends at a first longitudinal position, i.e. a shoulder or wall discontinuity. This discontinuous portion is a part of the range from the end 142 to the tip 180. The foremost portion 184 of the internal hole 178 has an internal shape different from that described above in the description of the cap 20. Rather than having a generally flat peripheral shoulder, such as a shoulder 148, the change in the sloped cut 182 is in the form of a rounded change 186. This change leads to one of an array of protrusions, chambers or sub-cavities indicated by 189, 190, 191, 192 or other tapered walls 188. Each of these protrusions is terminated by a round dome end 194 which is formed along a generally spherical arch or vault. These protrusions are provided with a plurality of cooling chambers. The flat portion of the gap indicated by 196 is to be stopped in the axial direction with respect to the inserted male electrode holder. In the region between the protrusions 189, 190, 191 and 192 is a protruding cooling arrangement, shown as a fin mechanism 200. In one embodiment, the axially rearwardly protruding end of the fin mechanism 200 may have a somewhat rounded cross-section and a somewhat Phillips screwdriver tip with a rounded end. . This cruciform extends radially and meets or extends a set of outwardly extending wings or fins, shown by way of illustration as an axially upstanding web 198. . These webs intersect at a central portion shown as fin pillars 201 and extend from the central portion. The fin pillar 201 may not have a round cross section, but has a larger large crossing dimension in a certain direction, and a smaller small crossing dimension in a direction shifted by half the angular pitch between the protrusions. Web 198 joins the outer perimeter that continues toward the center of flat portion 196 at the radially outermost portion of the column. The radial web 198 varies in thickness both in the radial and axial directions, but is thicker in the axial base (ie, the portion closest to the foremost portion 184 in the axial direction) and in the middle between adjacent protrusions. It is the thinnest at the plane indicated by 195, which is defined by the plane through the line. That is, the radially extending web portions can be inserted between the centers of a pair of adjacent protrusions, respectively, and can transfer heat so that heat is released from the tip 202. That is, the web acts as a partition between adjacent protrusions, thereby isolating the protrusions from one another. Moreover, the area of the heat transfer surface through which the coolant flows can be increased. The edge of the surface beyond which the coolant flow passes, that is, the edge of the surface where the coolant meets, is rounded rather than sharp, as shown. In operation, the coolant introduced axially and directed forward is divided by the cruciform portion of the fin mechanism 200 (ie, the cruciform portion functions as a flow separator) and is defined by the surface of the protrusion. It flows along the wall. These walls are smoothly rounded, function as wings that change the direction of flow backwards, and provide appropriate heat transfer to the liquid. Liquid leaving this area is drained backwards. The smooth surface arc extends over a curve greater than 120 degrees, and in one embodiment extends over a curve of approximately 180 degrees.

The height of the fin column 201 is indicated by δ ₈ , and the ratio of the height between the tip and the discontinuity of the wall indicated by δ ₉ is, for example, the ratio of δ ₃ to δ ₅ . Greater than. In one embodiment, the ratio of δ ₈ to δ ₉ is in the range of 2/3 to 9/10. Similarly, the minimum height of each web 198, which can be obtained by subtracting the [delta] ₁₀ dimensions from [delta] _9, which can be obtained as a percentage. In one embodiment, the ratio is in the range from 1/2 of the [delta] ₈ 4/5. That is, the fin column 201 protrudes from the adjacent minimal web 198 and stands in the axial direction. The web and protrusion arrangements shown are intended to represent many protrusions or many webbed arrangements, and in some cases two, three, four, five, six, seven. , Any of eight or more protrusions or webs. In addition, the distance from the welding tip surface or region 202, when measured in the axial direction, is closer to the tip 180 than the conventional or conventional one, and is actually cut from the shoulder discontinuity to the top of the parabola, or in some cases. The distance to the chip surface is within the range of 2/5 to 3/5.

  The head portion 174 has a chip or chip area 202 which can be left uncut as shown at 204 in FIGS. 5h and 5i, or initially shown in FIG. And may be shaved moderately, as shown at 206 in 5g. This makes it possible to use a weld surface having a diameter corresponding to the size of the weld ingot required for the thickness of the metal to be welded in combination with a curved surface close to a parabolic curve (or other curve).

  If the chip is used in an initial rounded end shape (eg, FIG. 5h) or if it is cut to an appropriate size before shipping to the end consumer (as in FIG. 5a or 5f), Some or all include a coating 70 as described above in the description of electrode 20. The welding electrode 120 can be made of any of the materials described above in the description of the welding electrode 20, and can be manufactured by the process described in the description of the welding electrode 20.

  Where a coated tip is used, in some cases, a weld cap formed as shown herein may be used in a welding process that includes using a weld cap in a welding tool that is clamped to two objects. it can. These two objects, such as metal sheets that are welded together, include zinc or nickel, or steel coated with zinc and nickel, advanced high-strength steel, aluminized or aluminum sheets. . Processing includes the use of the electrode without the step of conditioning the electrode prior to using the electrode with these materials or one of them. In such use, in some cases, the tendency to stick to the surface of the material being welded is reduced, and the tendency for copper to deposit on the workpiece is correspondingly reduced. As long as electrode degradation occurs over a long period of time, the use of the electrode involves a current phase process.

  Instead, as long as the electrode coating tends not to react to the workpiece, it can be removed from the surface of the workpiece, such as a zinc-based or zinc-coated workpiece, and the workpiece Can reduce or retard chemical alloying of the electrode with impurities extracted from the workpiece, and can reduce or retard electrode degradation accordingly.

  The internal fin mechanism for interaction with the coolant flow can help cool the electrode and can slow or not cause electrode annealing over a long period of time. . In some cases, such cooling allows more concentrated heating of the weld mass as opposed to heating adjacent electrodes.

  Various embodiments have been described in detail. Modifications to or additions to the above-described best embodiments can be made without departing from the nature, spirit or scope of the invention, and the invention is not limited to the details described above.

The accompanying drawings illustrate exemplary embodiments or embodiments that include the principles and aspects of the present invention. here,
It is a side view which shows an example of a male welding electrode. 1 b is a cross-sectional view of a symmetric longitudinal section of the welding electrode of FIG. It is the end elevation which looked at the welding electrode of Drawing 1a in the internal direction shown by arrow 2 of the figure. FIG. 2 is an enlarged detail view showing a surface covering in a contact end region of the welding electrode in FIG. 1 with hatching omitted for clarity. FIG. 2 is a side view of a female electrode similar to the male electrode of FIGS. 1a and 1b. 4b is a cross-sectional view of a symmetric longitudinal section of the welding electrode of FIG. 4a. It is the end elevation which looked at the welding electrode of Drawing 4a in the internal direction shown by the arrow of the figure. FIG. 1b is a side view showing an electrode instead of the electrode of FIG. 1a. FIG. 5b shows a first end of the electrode of FIG. 5a. FIG. 5b shows the opposite end of the electrode of FIG. 5a. FIG. 5d is a cross-sectional view of the electrode of FIG. 5a taken along line 5d-5d. It is the sectional view on the 5e-5e line of the electrode of FIG. 5a. FIG. 5b is a side view showing an electrode instead of the electrode of FIG. 5a. FIG. 5f shows a first end of the electrode of FIG. 5f. FIG. 5b is a side view showing another alternative electrode of the electrode of FIG. 5a. FIG. 5c shows a first end of the electrode of FIG. 5h.

Claims (11)

In welding electrodes that have a hollow body and are made mainly of copper-based materials,
The welding electrode is a first end for engaging with an electrode holder, the first end having an opening for supplying cooling liquid to the hollow body and for discharging from the hollow body Have
The welding electrode has a second end with a welding tip for engaging the object to be welded;
The hollow body is an array of chambers formed therein, the chamber having an array of chambers extending from the opening toward the welding tip,
The welding electrode has a web formed therein between a pair of adjacent chambers;
A welding electrode characterized by that. The welding tip has a coating comprising a titanium-based layer and a stack deposited on the titanium-based layer;
The stack includes a material that is more viscous than titanium carbide and has a higher melting temperature than zinc;
The titanium base layer has one of (a) titanium carbide and (b) diborotitanium as a main component;
The welding electrode according to claim 1, wherein the superposition includes at least one of (c) molybdenum and (d) nickel.   The hollow body has a weld tip, the tip forms a coating thereon, the coating has a first layer and a second layer, and the first and second layers are mainly made of titanium carbide. The welding electrode of claim 1, wherein the second layer comprises a higher weight percent titanium carbide than the first layer.   The electrode is a smooth arc-shaped surface, and includes a surface formed so as to change a direction of flow of the coolant mainly forward in the axial direction to a direction of flow backward in the axial direction. The welding electrode according to claim 1. The welding electrode is
(A) the first layer is an underlayer formed of a material that is deposited on a weld cap body of copper primarily and is at least 5 wt% molybdenum;
(B) the first layer is an underlayer formed of a material that is deposited at least on a copper weld cap body and is at least 5 wt% tungsten;
The welding electrode according to claim 3, wherein the welding electrode is selected from a set of welding electrodes composed of:   The chamber includes a smooth surface for contacting the coolant, and the smooth surface extends in an arc shape to change the direction of the coolant, and the arc has an angle greater than 120 degrees. The welding electrode according to claim 3. In the method of manufacturing a welding electrode,
A molded blank made primarily of copper material, having a shaft for fixing to the electrode holder and a head having a contact area for placement against the workpiece to be welded A step of preparing a molding blank;
Forming a main hole in the shaft portion;
Forming a plurality of sub chambers in the head, wherein the sub chambers communicate with the main holes by liquid;
The manufacturing method of the welding electrode characterized by having.   Forming a contact region on the head for contacting an object to be welded; and forming a coating on the contact region of the head; and forming the coating. 8. The method of claim 7, further comprising: depositing a first layer of a first composition on the contact area of the head; and depositing a second layer on the first layer. The manufacturing method of the welding electrode of description.   The method for producing a welding electrode according to claim 7, wherein the step of forming the sub chamber includes forming at least one fin in the blank.   The method for manufacturing a welding electrode according to claim 8, wherein a shot peening process is performed at least in the contact region prior to the process of forming the covering. The method includes the step of forming the blank to have a head positioned axially forward of the shaft portion;
(A) giving the head a shape formed along a curve that is mainly one of (i) a parabola and (ii) an elliptic curve when viewed from the side; and (b) the head And, when viewed from the side, is a step of giving a shape formed mainly along a curve that is either (i) a parabola or (ii) an elliptic curve, the curve being the forefront of the head Followed by the step of having a vertex at the position of and removing the vertex to produce a flat end face of the head;
A process selected from at least a set of processes consisting of:
The manufacturing method of the welding electrode of Claim 7 characterized by the above-mentioned.

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