JPH11197840A - Welding method and member for percussion welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress thermal stress on a planar member, with weldability superior to arc welding, under such advantage as short welding time and contact pressure, by making a projected front face a tapered face with small projections as the apex, protecting the planar member from blow holes and shrinks, and carrying out percussion welding. SOLUTION: Small projections 11 of a planar member 1 is brought into contact with a base material 2, with a welding electrode 3 abutted on the planar member, actuating a prescribed contact pressure with a spring 4, energizing in this state and instantaneously melting and evaporating the small projections 11 by heat generated through the energization. By this melting and evaporation of the small projections 11, a space between the projecting part 12 of the planar member 1 and the base material 2 is thermally ionized by the high temperature of metallic vapor, and igniting an arc, with the arc discharge continued until the member again comes into contact with the base material 2 with the spring pressure. A gap T between the planar member surface 120 around its projected part 12 and the base material 2 is designed to be thicker compared with a gap T between the projected part 12 and the base material 2; hence, expansion of the arc beyond the projected part 12 is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for percussion welding a flat welding member to a base material and a percussion welding member.

[0002]

2. Description of the Related Art Conventionally, percussion welding is generally used to implant studs (solid rods, hollow rods such as bolts, dowels, pins, lead wires, etc.) into a base material. -A small projection as a bell is machined, and this stud is brought into contact with the base material with a predetermined pressure by a spring.
The bell is instantly dissolved and evaporated. The dielectric strength is reduced by the thermal ionization based on the high temperature of the metal vapor, an arc is generated between the stud and the base material, and the stud and the base are heated by the arc heat maintained until the stud comes into contact with the base material. The welded portion of the material is melted, the arc discharge is terminated by the pressing of the stud against the base material by the spring, and the welding is completed.

[0003] If a plate-like member can be welded by this percussion welding method, it is possible to improve the work efficiency and eliminate the adverse effect on the base material by reducing the welding time and the contact pressure. Although it is advantageous, when the percussion welding method is used to weld a flat member without simply providing a navel,
The arc between the flat member and the base metal spreads around the above-mentioned navel, and the behavior becomes unstable due to a slight difference in shape, etc., so that the heat energy is not concentrated at the target position and the penetration is insufficient. However, satisfactory welding cannot be expected.

The inventor of the present invention processes a projection 12 'with a small projection 11' on the surface of a welding member 1 'as shown in FIG. 8, and uses the small projection 11' as a navel. And welding the projection 12 'to the base metal by percussion welding ".
No.-8610). In order to weld the flat member to the base material by this welding method, a convex portion with a small projection is formed on the flat member, and the small projection 11 'of the flat member 1' is formed as shown in FIG. Is brought into contact with the base material 2 'and the welding electrode 3' is brought into contact with the plate-like member 1 ', and a predetermined contact pressure is applied by a spring 4'. It melts and evaporates instantly with the heat generated by the current. By the dissolution and evaporation of the small projections 11 ', a discharge gap corresponding to the height of the navel is formed between the projection 12' of the plate-like member 1 'and the base material 2'. The arc discharge is sustained until the arc is ignited by the thermal ionization at the high temperature and the plate member comes into contact with the base material again by the spring pressure. In this case, the gap thickness T between the base member 2 'and the flat member plane 120' around the convex portion 12 'of the flat member 1' is the gap thickness t between the convex portion 12 'and the base material 2'. Since the dielectric strength in the former gap is higher than that of the latter, and the potential gradient in the former gap is weaker than that of the latter, the occurrence of arc in the former is suppressed and only the latter is used. Since the arc can be generated at the convex portion 11 'and the arc density can be increased, the arc density can be increased.
The base material portion 21 'facing the 2' and the convex portion 12 'can be sufficiently melted. Eventually, the convex portion 12 'is pressed against the base material portion 21' by the pressure of the spring 4 'and the arc discharge disappears, and the welding is completed as shown in FIG. .

[0005]

However, the present inventor has continued to study the percussion welding of the flat plate-shaped member, and has conducted various tests. There was a case where welding occurred and welding strength was lowered. In welding using arc heat, the arc behavior is not always constant due to various disturbances, and even in this percussion welding, variations in welding strength due to disturbances cannot be avoided. In addition, the gap between the projection and the base metal is not uniform with respect to the melting center (the position of the small projection) due to the processing accuracy of the projection and the setting accuracy of the welding member, and the radial flow of the molten metal becomes non-uniform. It is also presumed to be a serious cause.

An object of the present invention is to form a projection with small projections on the surface of a plate-shaped welding member, and use the small projections as a navel to perform percussion welding of the projections to a base material. It is an object of the present invention to prevent the occurrence of shrinkage and sink and further improve the welding strength.

[0007]

According to the present invention, there is provided a welding method, comprising: forming a projection having small projections on a surface of a flat welding member; and using the small projections as a navel. Is percussion-welded to the base material, wherein the front surface of the convex portion is a tapered surface having the above-mentioned small protruding portion as an apex, and the tapered surface is usually a cone. The taper surface has a slope of 3 ° to 15 °.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG.
FIG. 1B is a plan view of an example of the flat welding member 1 used in the invention according to the invention.
(B) a cross-sectional view, each showing a small projection 11 as a navel;
The convex portion 12 having the conical surface 10 having the small projection portion as the apex and having the front surface is machined on the welding surface side. As shown in FIG. 1C, the inclination of the conical surface 10, that is, the taper angle β ° is β ° = (180 ° −2) where the apex angle is α °.
α °) / 2.

The projections 12 with small projections can be squeezed out at once using a press die. 2A and 2B show different examples of the squeezing type.
In the case of (a), the back side of the projection is formed into a curved surface. It is to be noted that such a shape processing is naturally possible even in casting or shaving, and an appropriate processing method may be selected as needed.

In order to weld the above-mentioned flat member to the base material by the welding method according to the present invention, the small projection 11 of the flat member 1 is brought into contact with the base material 2 as shown in FIG. At the same time, the welding electrode 3 is brought into contact with the plate-shaped member 1, a predetermined contact pressure is applied by the spring 4, and the small projections 11 are instantaneously melted and evaporated by the energized heat generated in this state. Due to the melting and evaporation of the small projections 11, the space between the projections 12 of the plate-like member 1 and the base material 2 is thermally ionized at a high temperature of the metal vapor, and the arc is ignited. The arc discharge is continued until the spring comes into contact with the base material again by the spring pressure.

The arc discharge, that is, the behavior of the arc plasma, is difficult to confirm even with a high-speed camera because the arc discharge time is extremely short, several milliseconds. Similarly, it is assumed that the arc tends to spread outward from the center while rotating the welding surface. However, the gap between the flat plate member 120 around the convex portion 12 of the flat plate member 1 and the base material 2 is made thicker than the gap between the convex portion 12 and the base material 2 so that insulation at the former gap is achieved. Since the proof stress is made higher than the latter and the potential gradient in the former gap is made weaker than the latter, the occurrence of arc in the former can be suppressed and the arc can be generated only in the latter, and the convex portion can be formed. The spread of the arc beyond the periphery of the circle 12 can be prevented.

Since the arc density can be increased by intensively generating the arc in the convex portion 12, the convex portion 12 and the base material portion 21 facing the convex portion 12 are sufficiently melted. be able to. Eventually, the convex portion 12 is pressed against the base material portion 21 by the pressure of the spring 4, and the arc discharge disappears, and the welding is completed as shown in FIG.

Now, assuming that the angle between the center line of the projection 12 and the base material 2 is slightly inclined from the normal 90 °, in the present invention, the front surface of the projection 12 has the small projection 11 as the apex. Since the projection is formed on the conical surface 10, the distance between the projection 12 and the base material 2 along the radial direction around the small projection 11 is smaller than when the front surface of the projection is a flat surface having a small projection in the center. The gap state is hardly different in any radial direction. On the other hand, when the front surface of the convex portion is a flat surface, the gap state becomes completely reverse gradient in the forward direction and the reverse direction with respect to the above inclination centering on the small projection, and the molten metal in the radial direction The flowability will be greatly different.

Therefore, due to the processing accuracy of the projection 12 and the setting accuracy of the projection 12 on the base material 2, even if the angle between the center line of the projection and the base material is slightly inclined from the normal 90 °, the small projection 11 The radial expansion due to the pressure of the molten metal around the spring 4 by the spring 4 and the plasma airflow or surface tension,
Since the welding method of the present invention can be made sufficiently uniform, it is possible to prevent the occurrence of cavities and the like and to ensure excellent welding strength.

In the above, in order to concentrate the arc in the gap between the convex portion 12 and the base material 2, the welding member surface around the convex portion is compared with the distance t between the edge of the front surface of the convex portion and the base material. It is necessary to make the distance T between the conical surface 10 and the base material sufficiently large, and this distance t is determined by the taper angle of the conical surface 10. It depends on the distance T between the surface and the base material, and thus the height of the projection 12. Further, under a condition of a large current and a long arc discharge time, the taper angle can be increased to a certain extent due to a large amount of the molten metal in the convex portion 12, but when the taper angle is small, the taper angle can be increased. The welding conditions are such that the melting amount of the portion is small, and the taper angle is also affected by the welding conditions.

The height of the projections (not including the height of the small projections) is 1 to 2 mm, the height of the small projections is 0.5 mm, the charging voltage of the welding machine is 150 to 275 V, and the peak current is about 8000
In the case of welding at 16000 A and arc discharge time of 2 to 10 milliseconds, it is appropriate that the taper angle of the conical surface on the front surface of the projection is 3 to 15 degrees. The distance between the plate-like member 1 and the base material 2 after percussion welding according to the present invention can be made smaller as the height of the projections 12 is reduced, and the space can be made as small as possible. This is advantageous in terms of the above-mentioned sense of stability, prevention of intrusion of foreign matter into the gap, improvement of the positional accuracy of the welding member (work), and rust prevention.

As shown in FIG. 4, the welding method according to the present invention can be carried out by providing the insulating layer 7 on the surface 120 of the plate-like member around the convex portion 12. In this embodiment, the small protrusions 11 of the plate-shaped member 1 are brought into contact with the base material 2 and the welding electrode 3 is brought into contact with the plate-shaped member 1, and the electrode 3 is used as an anode,
A predetermined contact pressure is applied by the spring 4, and the small projections 11 are instantaneously melted and evaporated by the energized heat generated by energizing in this state. And the arc discharge is extinguished to complete the welding.

In the embodiment described above, the distance between the periphery 120 of the convex portion of the welding member and the base material 2 is made larger than the distance between the convex portion 12 of the welding member 1 and the base material 2 in FIG. As a result, the dielectric strength in the former gap is higher than that of the latter,
In addition, the potential gradient in the former gap is made weaker than the latter,
The arc is generated only in the latter (between the convex portion and the base material) by suppressing the arc in the former. However, in the welding method of another embodiment, as shown in FIG. Since the insulating layer 7 is provided around the protrusion 12 of the member 1, the flow of electrons due to arc discharge is hindered around the protrusion 12, and the periphery 120 of the protrusion of the welding member 1 and the base material 2 Even if the interval T is not so large, or even if the charging voltage is considerably increased and the current value is increased, the occurrence of arc around the convex portion 12 is well suppressed, and the convex portion 12 and the base material portion 21 The arc can be generated only during the period.

Thus, according to this embodiment, the arc discharge is caused only by the projections even when the height of the projections is low, only by providing the insulating layer on the surface of the welding member around the projections. To reduce the height h of the projections, and to ensure arc discharge only at the projections even under a high charging voltage, and to increase the penetration depth by increasing the welding energy. Can be achieved. Actually, the capacitor capacity is 180,000 μF, the charging voltage is 150
v, when the height of the convex portion is 0.5 mm, when there is no insulating layer,
The plating evaporates to about 2 mm around the projection, and the thermal energy diffuses around the projection due to the irregular behavior of the arc. However, when an insulating layer is provided, the generation of the arc is immediately below the projection. Only got it. Charge voltage 275v, convex part height 1.0
In the case of mm, heat energy was similarly diffused up to about 4 mm around the convex portion when there was no insulating layer, but when the insulating layer was provided, arc generation was kept just below the convex portion.

The insulating layer 7 is made of, for example, an insulating film, tape, plate, or insulating paint (eg, acrylic lacquer, synthetic resin emulsion), and is used for electrical energy and arc conduction during welding. Any suitable material can be used as long as it can withstand heat. Normally, the insulating layer is provided on the entire surface of the welding member except for the convex portion. However, as the charging voltage is increased and the convex portion is decreased, the range of the spread of the arc around the convex portion is increased. Therefore, an annular insulating layer having a predetermined width and including the convex portion may be formed in accordance with the degree of increase in the charging voltage or the degree of decrease in the height of the convex portion.

In the present invention, as shown in FIG. 5, an electric resistance layer 70 may be provided on the entire surface of the flat plate-shaped member 1 for implementation. In this embodiment, the flat member 1
The small protrusion 11 is brought into contact with the base material 2 and the welding electrode 3 is brought into contact with the plate-shaped member 1, the electrode 3 side is used as an anode, a predetermined contact pressure is applied by a spring 4, and electricity is supplied in this state. The protrusions 11 are instantaneously melted and evaporated by the heat generated by the energization, and finally, the protrusions 12 are pressed against the base material portion 21 by the pressure of the spring 4 to extinguish the arc discharge and the welding is completed.

In this welding method, the electric resistance layer 70
Is set so as to be 15 × 10 ⁻⁴ Ω or less, compared with the resistance value (about 3 × 10 ⁻⁴ Ω) in the normal state of the galvanized steel sheet without the electric resistance layer 70. Since the resistance value is suppressed to a very low value, the generation of arc around the convex portion 12 is well suppressed, and the arc can be generated only in the latter (between the convex portion and the base material).

The function of blocking the electron flow by the electric resistance layer 70 around the projection 12 is presumed to be weaker than the function of preventing the electron flow by the insulating layer 7.
In comparison with the case where there is no protrusion, the height of the convex portion can be reduced and the penetration depth of the convex portion can be increased, so that the distance between the flat plate member 1 and the base material 2 after percussion welding is reduced. In addition to being able to enjoy the benefits of being able to increase the welding strength to a greater or lesser degree, even if the welding members and base metal have oil stains and aging oxide films, and even if they have been provided with an anticorrosion film, The welding can be performed as it is, and the advantage that no pretreatment (cleaning or peeling of the anticorrosion film) is required can be obtained.

The resistance value of the electric resistance layer 70 is 3.5 ×
It is preferable to set the ^resistance to 10 ⁻⁴ to 15 × 10 ⁻⁴ Ω. At 3.5 × 10 ⁻⁴ Ω or less, there is almost no effect as an electric resistance layer. At 15 × 10 ⁻⁴ Ω or more, the current-carrying resistance becomes too high, and a stable arc is not obtained in normal capacitor charging / discharging type current-carrying. Because it is difficult to obtain A more preferred resistance value is 6 × 10 ⁻⁴ to 15 × 10 ⁻⁴ Ω.

The electric resistance layer 70 is formed by applying a cutting oil, applying a rust preventive paint (for example, zinc chromate), or applying a black dyeing treatment (a dense and stable black magnetic iron oxide film on a steel surface is subjected to an alkali immersion oxidation method). , Dry oxidation method, heated steam method,
A method of forming by an anodizing method or the like can be used. The percussion welding member used in the above embodiment may be formed by forming the electric resistance layer after molding the percussion welding member described with reference to FIGS. 1 and 2, or by forming the electric resistance layer before molding. It can be obtained by forming and then molding into the percussion welding member described with reference to FIGS.

In the present invention, the diameter of the projection (welding area)
In consideration of the power performance and welding strength of a normal welding machine body, the limit is usually φ12 mm, and in general, φ10 mm
mm or less is appropriate. In the present invention, the shape of the convex portion is not limited to a columnar shape, and the rising is preferably vertical as a problem at the time of welding work, but a slight inclination is allowed in processing.

In the present invention, if the height of the small projections is too high, the shape accuracy of the small projections, the surface layer (plated layer)
And the reaction force at the time of evaporation when energized greatly fluctuates, so that the arc discharge time differs even under the same welding conditions, and the arc becomes difficult to ignite. In the case of squeezing, the plate thickness in the vicinity of the convex portion is reduced in order to raise the navel, and a hole may be formed in the member due to arc discharge heat.
0v, 0.5m when the work thickness is 2-3mm
m is preferable. The diameter of the small protrusion is φ1 m when the charging voltage is 150 V and the peak current value is 7000 A in consideration of the current density so as to cause instantaneous melting.
m.

In the welding method according to the present invention, a plurality of projections with small projections can be machined on the welding surface side of the flat member, and these projections can be welded simultaneously. in this case,
The distance between the edges of the adjacent protrusions (indicated by L in FIG. 1) is appropriately determined so that the arcs at the adjacent protrusions do not become unstable due to electromagnetic interference. It is necessary to have a minimum of about 30 mm under a welding current of 7000 to 12000 A.

In the welding method according to the present invention, in addition to the flat member, a welding member having a flat portion, for example, as shown in FIG. A small protrusion can be machined into a convex portion, and the small protrusion can be used as a navel to perform percussion welding of the convex portion to the base material. The detachable support of the welding member to the welding electrode can be performed by a jig according to the shape of the welding member.

FIG. 7 shows an example of the welding equipment used in the present invention. In FIG. 7, reference numeral 5 denotes a device for raising and lowering an electrode and a work. A header 53 is attached to a piston rod 52 of a cylinder 51, and the welding electrode 3 is supported on the header 53 via a spring 4. . Reference numeral 1 denotes a flat plate-shaped member having an ear portion 13, which is detachably supported on the welding electrode 3 by a stopper pin 14 at the ear portion 13.
Reference numeral 12 denotes a projection with a small projection 11 formed on the flat member 1. 2 is a base material. Reference numeral 6 denotes a welding machine main body equipped with a condenser and a control device. The output end of the condenser is connected to the welding electrode 3 and the base material 2 by cables.

The welding procedure when welding using this equipment according to the present invention is as follows. The piston rod of the cylinder is raised to support the plate-like member on the welding electrode. The piston rod is lowered to a predetermined position, and the flat member is brought into contact with the base material by the compressive stress of the spring. At this stage, the welding surface of the projection of the flat member is floating above the base material by the height of the small projection of the flat member. The electric energy charged in the condenser of the welding machine body is supplied to the welding electrode, and the small protrusions are instantaneously melted and evaporated, so that the plate-like member floats by the height of the navel, and the base metal An arc discharge is generated for several milliseconds while being pressed against the substrate, and the arc melts the convex portion of the flat member and the base material portion facing the convex portion. After the arc discharge is continued for several milliseconds, the convex portion of the flat member is pressed against the base material by the compressive stress of the spring, the arc discharge disappears, and the welding is completed. Note that a gradually decreasing current flows for a short time until the capacitor of the welding machine is completely discharged.

[0032]

[Embodiment 1] 1 mm diameter and 0.5 height in the center
12 mm in diameter, 1.5 mm in height with small projections of
The convex part with a slope of about 5.2 ° of the front conical surface is 2.3 mm thick.
Was processed into a hot-dip galvanized steel sheet to obtain a welding member.

This welding member was applied to a base material of a hot-dip galvanized steel sheet without oil application (a cutting oil was applied immediately before welding) and no oil application, using a capacitor welding machine having a capacitor capacity of 336000 μF, a charging voltage of 150 V and a spring. Pressure 5
Percussion welding was performed at kgf. At this time, a peak current value of 9600 to 11000 A, energization time (time from the start of energization until the electric pole value reaches the peak value) 2.5 ms, arc time
The discharge time was 4-5 milliseconds.

The welding strength of the sample in the case of oil application (average tensile strength of 50 samples) is 804 kgf,
Welding strength of sample without oil application (sample 50
The average tensile strength was 246 kgf. Also,
When a cross section of the welded portion was inspected by cutting, no nest or pulling was observed in any of the samples, and the sample was in a good state of penetration.

[Comparative Example] In comparison with Example 1, a welding member having a flat front surface (with a gradient of 0 °) instead of a conical front surface was used, and the welding conditions were the same as in Example 1. . The welding strength of the sample in the case of oil application (average tensile strength of 50 samples) was 437 kgf, and the welding strength of the sample without oil application (average tensile strength of 50 samples) was 115 kgf. Further, when the cross section of the welded portion was inspected by cutting, nests and towing were found in about 10% of the sample.

[Examples 2 to 5] In contrast to Example 1, welding members were used in which the slope of the conical surface in front of the convex portion was about 3 °, about 8.1 °, about 10 °, and about 14 °. The welding conditions were the same as in Example 1.
And the same. The welding strength of each sample (average tensile strength of 50 samples) is as shown in Table 1. In addition, no nest or pulling was observed in any of the samples, and the samples were in a good penetration state.

[0037]

[Table 1]

[0038]

According to the welding method of the present invention, a flat member can be welded by percussion welding while preventing the occurrence of nests and pulling. Therefore, the plate-shaped member can be welded under the advantages of percussion welding such as a short welding time of several milliseconds and a low contact pressure of several kgf. Welding can be performed with stress suppressed well.

Also, unlike resistance welding, large power is not required, and breakage of the plating layer around the weld can be prevented.

[Brief description of the drawings]

FIG. 1A is a plan view showing an example of a percussion welding member used in the present invention, and FIG.
FIG. 1 is a cross-sectional view taken along a line in FIG. 1A, and FIG. 1C is an explanatory view of a gradient of a welding member.

FIG. 2 is a view showing different molds used for processing the percussion welding member of the present invention.

FIGS. 3A and 3B are drawings showing an embodiment of a welding method according to the present invention, wherein FIG. 3A shows a state before welding, and FIG. 3B shows a state after welding.

FIG. 4 is a drawing showing another embodiment of the welding method according to the present invention.

FIG. 5 is a drawing showing another embodiment of the welding method according to the present invention.

FIG. 6 is a drawing showing another example of a percussion welding member used in the present invention.

FIG. 7 is a drawing showing an example of a welding facility used in the present invention.

FIG. 8 is a drawing showing a welding member used for percussion welding proposed earlier.

FIG. 9 is a view showing a previously proposed percussion welding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Welding member 10 Conical surface 11 Small projection 12 Convex part 120 Welding member surface around convex part 2 Base material 3 Welding electrode 4 Spring

Claims (4)

[Claims] 1. A method of processing a projection with small projections on the surface of a flat welding member and percussively welding the projections to a base material using the small projections as a navel. A welding method, wherein the front surface of the convex portion is a tapered surface having the small projection portion as an apex. 2. The taper surface is a conical surface, and the gradient of the taper surface is [180 ° −2α when the vertex angle of the conical surface is α °.
°) / 2] is set to 3 ° to 15 °. 3. A front surface having a small projection, and a convex portion having a conical surface having the small projection as an apex is machined on the surface, the small projection is used as a navel, and the convex portion is formed as a welded portion. Plate-shaped percussion welding member. 4. The method according to claim 3, wherein the convex portion is provided by squeezing.
A plate-shaped percussion welding member as described in the above.