JPH06114563A - Electric resistance welding method for aluminum-coated steel wires - Google Patents

Abstract

PURPOSE:To perform electric resistance welding which is being excellent in corrosion resistant effect and welding strength by melting only an aluminum- coated layer by primary energizing to allow steel wires to come into contact with each other and then, performing welding by secondary energizing. CONSTITUTION:The aluminum-coated steel wires 1 and 2 are crossed each other to perform electric resistance welding. At that time, only the aluminum- coated layer of a crossed contact part is melted by primary energizing to allow the steel wires 1 and 2 to come into contact with each other and then, the welding is performed by secondary energizing. In primary energizing, an applied electric current is increased and the energizing time is shortened and in secondary energizing, the applied electric current is decreased and the energizing time is extended. The welding is performed under conditions of a welding work stroke H of 3-6mm, the pressurizing force of 1-5kg/cm, the primary energizing time of 5-30 cycles (electric power frequency), the primary applied current of 3000-150000 (A), the secondary energizing time of 10-60 cycles (electric power frequency) and the secondary applied current of 1000-5000 (A). Consequently, a smooth welded body without producing burrs can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention of the present application relates to a coated wire rod made of a composite material having different electric resistance, that is, an aluminum-coated steel wire having a coating layer of aluminum on the surface of the steel wire to enhance corrosion resistance, particularly aluminum. The present invention relates to an electric resistance welding method for welding aluminum-coated steel wires having a space factor up to about 50% to a wire mesh or the like in a crossed state.

[0002]

2. Description of the Related Art Conventionally, a steel wire alone, a galvanized steel wire obtained by galvanizing a steel wire, or a stainless steel wire has been used for manufacturing a wire mesh or the like by using an electric resistance welding method using a metal wire. However, steel wire can obtain strong welding,
Since red rust is likely to occur, surface treatment with plating or paint is required.If the plating layer of galvanized steel wire is too thick, the steel of the core wire and zinc alloy during welding, resulting in reduced welding strength, corrosion resistance and appearance. In addition, the weld strength of the stainless steel wire varied due to the heat effect at the welded part, and the corrosion resistance was changed due to discoloration.

Therefore, it has been attempted to use an aluminum wire or an aluminum alloy wire which has good corrosion resistance and good appearance, but since these wires have a very high electric conductivity, the amount of energizing current becomes excessive, which is inconvenient in terms of equipment. Even if welding was performed with a large current, it was impossible to obtain sufficient welding strength because it was very easily oxidized.

However, in recent years, an aluminum-coated steel wire having an aluminum coating layer on the surface thereof has a more stable surface layer than a galvanized steel wire or the like, and is not only mechanically strong but also has corrosion resistance. It has been widely used for fences, animal cages, bird cages, etc. because it has enough.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As a commonly used aluminum-coated steel wire, high-purity aluminum having a purity of about 99.8 to 99.6% is hot-extruded onto the steel wire and melted. A clad layer formed by plating, tape attachment, or coating by a powder sintering method, etc., and finished to a specified outer diameter is used, but the intersection part using such aluminum coated steel wire is electric resistance welded. , Aluminum and steel have electric resistance (Al = 2.8 μΩ-cm, Fe = 10 μΩ-c).
Since m) differs by several times or more, it is difficult to obtain a good weld due to a large current leakage by the normal welding method, and aluminum changes into an oxide immediately after melting. Even with technical experience, the aluminum coating layer on the surface of the steel wire will melt and expose the steel wire portion, reducing the corrosion resistance near the cross welds, or the aluminum coating will interfere with the joining. Problems such as only low welding strength being obtained, or the appearance of aluminum burrs having a bad appearance, which may damage animals due to burrs when used as animal cages or bird cages. was there.

[0006]

As one means for solving the above problems, the applicant has proposed to use a coated steel wire having a large resistance value of an aluminum coating layer.
Proposed in No. 82. That is, the purity on the steel wire is 9
Aluminum or Fe of 9.5% or less is 0.5 to 1.0% by weight, Si is 0.5 to 1.5% by weight, and the total amount of both is 0.5.
~ 2.0 wt%, Mg 0.5-2.0 wt%, Mn 0.5-
By using an aluminum-coated steel wire having a coating layer formed of an aluminum alloy containing 1.5% by weight,
By increasing the resistance value of the aluminum coating layer to reduce the leakage of welding current, it is intended to obtain a product having a beautiful appearance and high welding strength. Apart from this method, as a result of extensive studies to solve the above problems, the invention of the present application, the joint strength and the finished appearance of the aluminum-coated steel wire, the outer diameter of the steel wire, the thickness of the aluminum coating layer, It was discovered that it is related to the welding work stroke and pressure, and the aluminum coating layer was instantly softened by a large current under a constant pressure and pressure time,
The primary energizing current value to be melted, and the secondary energizing current value after melting, in the molten liquid layer of aluminum, are the optimum energizing time and holding time for supplying and joining the steel cores as welding current to each other. By selecting, the relationship between the overlap thickness A before welding and the overlap thickness B after welding at the intersection of the steel wires should be within the deformation in the range of 88 / 100A ≧ B ≧ 68 / 100A. It was made to weld.

That is, when welding is carried out, the aluminum coating layer of the steel wire is melted and removed only by the portion where the steel wires contact each other by conducting the current in two stages of primary and secondary energization. It was stopped to obtain a strong joint between the steel wires. When the same two-step current welding was carried out using the coated steel wire described in Japanese Patent Application No. 3-254182, the aluminum coated steel wire produced a similar good appearance. , In terms of manufacturing cost, I couldn't find any special value to adopt.

[0008]

As shown in FIG. 2, aluminum-coated steel wires 1 and 2 having wire diameters D'and D ", respectively, are overlapped on a lower electrode plate of a welding machine in which welding electrodes are arranged vertically. When placing in a combined state and performing electric resistance welding,
First, in order to melt and remove the aluminum jacket of the joining portion, the distance from the upper surface of the aluminum-coated steel wire to the upper electrode, that is, the welding work stroke H is set to 3 to 6 mm, and the initial pressing time is set to 5 to 5. Applying a pressure of 1 to 5 kg / cm ² during 60 cycles (power frequency),
5 to 3000-15000 amps as the primary energizing current
By energizing for ~ 30 cycles (electric power frequency), the aluminum jacket is melted, and the steel wires are kept in contact with each other while cooling. Subsequently, the secondary energizing current is 1000 to 5
000 amperes are energized for 10 to 60 cycles to join the steel wires together, hold for 5 to 30 cycles and then open to complete the welding operation. The welding state at this time is as shown in FIG.

By carrying out the welding work in this way, only the aluminum coating layer at the joint portion can be rapidly melted and removed by passing a large current as the primary energizing current in a short time, and the other aluminum coating layer portions can be removed. It was possible to efficiently and firmly join steel wires to each other without causing scratches or welding damage, and to obtain a welded body of aluminum-coated steel wire with a good appearance.

Here, the welding work stroke is limited because if the stroke is too long, the impact point response of the electrode becomes slower and scratches occur at the contact surface between the electrode and the aluminum coating layer, so that the impact rate is improved. This is because the impact at the time of pressurization is reduced and the initial pressurizing step can be smoothly performed. If the initial pressurization time is specified too short, it is easy to give impact to the wire or welder, and if it is too long, the shot speed will decrease. This is because the appearance of abnormalities on the surface of the aluminum layer and the occurrence of welding flash due to sparks increase.

The primary energizing current is specified because aluminum has a small electric resistance, so if the electric current is small, it escapes without being heated, and if it is too large, it melts.
If the primary energization time is too short, the aluminum layer will not melt, and if it is too long, even the steel wire may melt.

The secondary energizing time and the secondary energizing current are limited because the energizing time is too short or the steel wire is not joined when the energizing current is too small, and the energizing time is too long or the energizing current is too large. This is because even if the steel wire is too large, even the steel wire will melt and deform.

The reason why the two-stage energization is applied is that it is necessary to energize a large current for a short time in order to melt and remove the aluminum coating layer having a small electric resistance and a large thermal conductivity. This is because for strong welding between the two, it is necessary to keep the current small because a large current may cause excessive heat generation and the steel wire may melt.

If the holding time after energization is too short, the welding intersection may be peeled off, and if it is too long, the welded part is severely deformed and the appearance is deteriorated.

[0015]

EXAMPLES Next, the invention of the present application will be described based on examples. Welding work was performed by the apparatus shown in FIGS. The wire rods used were all aluminum-coated steel wires with a wire diameter of 4.0 mmφ and a powder-sintering method with an aluminum space factor of 25%.

[Example 1] (Experiment No. 2) Welding work stroke: 3.Omm, initial pressurization time: 1
5 cycle time, primary energization time: 5 cycle time,
Primary energization current: 10000A, Secondary energization time: 15 cycles time, Secondary energization current: 2500A, Holding time after energization: 10 cycles time, Pressurization force: 2.0kg / cm ² As a result of welding under the above setting conditions, The change in the overlapping thickness of the wire rods is 78%, no elution protrusions or burrs are found on the wire rods, the appearance is good, and the shear fracture strength of the weld is 32k
g / mm ² was obtained.

[Example 2] (Experiment No. 4) Welding work stroke: 4.0 mm, initial pressing time: 1
5 cycle time, primary energization time: 5 cycle time,
Primary energization current: 10000A, Secondary energization time: 15 cycles time, Secondary energization current: 2500A, Holding time after energization: 10 cycles time, Pressurization force: 2.0kg / cm ² As a result of welding under the above setting conditions, The change in the overlapping thickness of the wire rods was 70%, the generation of elution protrusions and burrs on the wire rods was observed, and the appearance was also poor.

[Example 3] (Experiment No. 6) Welding work stroke: 4.0 mm, initial pressing time: 1
5 cycle time, primary energization time: 5 cycle time,
Primary energization current: 10000A, Secondary energization time: 15 cycles time, Secondary energization current: 2500A, Holding time after energization: 10 cycles time, Pressurization force: 2.0kg / cm ² As a result of welding under the above setting conditions, The change in the overlapping thickness of the wire rods is 75%, no elution protrusions or burrs are generated on the wire rods, the appearance is the best, and the shear fracture strength is 35 kg.
/ Mm ² was obtained.

[Example 4] (Experiment No. 17) Welding work stroke: 8.0 mm, initial pressing time: 1
5 cycle time, primary energization time: 5 cycle time,
Primary energization current: 10000A, Secondary energization time: 15 cycles time, Secondary energization current: 2500A, Holding time after energization: 10 cycles time, Pressurization force: 2.0kg / cm ² As a result of welding under the above setting conditions, The change in the overlapping thickness of the wire rods was 50%, the generation of elution protrusions and burrs on the wire rods was observed, and the appearance was also poor.

[Example 5] (Experiment No. 22) Welding work stroke: 5.0 mm, initial pressurization time: 1
5 cycle time, primary energization time: 5 cycle time,
Primary energization current: 10000A, Secondary energization time: 15 cycles time, Secondary energization current: 2500A, Holding time after energization: 10 cycles time, Pressurizing force: 3.0kg / cm ² As a result of welding under the above setting conditions, The change in the overlapping thickness of the wire is 75%, no elution protrusions or burrs are found on the wire, the appearance is good, and the shear fracture strength is 34 kg / mm ²
Things have been obtained.

For other examples, the results of welding conditions, wire rod characteristics and welding characteristics are summarized in Tables 1 to 4. And based on this, FIG. 5 shows the relationship between the shear strength and the overlapping thickness ratio of the intersecting portions of the wire rods in a diagram.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

Further, a soft steel wire such as SWRH8 shown in JIS 3505 is used as the wire steel wire. However, when hard steel wires are welded together, a quenching phenomenon occurs during welding and a satisfactory strength cannot be obtained. This is because, in the case of combination welding of a hard steel wire and a mild steel wire, welding strength with no problem in strength can be obtained.

Therefore, as a result of repeated examination of various tests on the thus obtained welded product, it was concluded that a shear fracture strength of 30 kg / mm ² or more is sufficient for practical use. .

From the above, it can be seen that the material having a good appearance and capable of being put to practical use must be within the range of the area C in FIG.

Therefore, in order to do so, when the outer diameters of the two aluminum-coated steel wires are D ′ and D ″, respectively, the diameter of the steel wire which is the core material of one aluminum-coated steel wire D ′ is D. ₁ , the thickness of the coating layer is d ₁ , the diameter of the steel wire which is the core material of the other aluminum-coated steel wire D ″ is D ₂ , and the thickness of the coating layer is d ₂ , the intersection of both steel wires is Overlap thickness before welding in A [A = D ₁ + D ₂ +2 (d ₁ +
d ₂ )] and the overlap thickness B after welding is 88/1.
It is necessary to perform the welding operation according to the process as shown in FIG. 3 so that the deformation range is 00A ≧ B ≧ 68 / 100A. By doing so, the state shown in FIG. 4 is obtained and the coated steel wire is welded.

However, the welding work conditions for satisfying the above requirements are as follows: welding work stroke H: 3 to 6
mm, applied pressure: 1 to 5 kg / cm, initial pressurization time t ₁ :
5 to 60 cycles (power frequency), the primary energizing time t _2:
5 to 30 cycles (power frequency), primary energizing current: 30
00 to 15,000 amperes, cooling retention time t _3: 0~3
0 cycles (power frequency), the secondary current supply time t _4:. 10 to
60 cycles (power frequency), secondary current: 1000
5000 amps, retention time after the energization t _5: 5~30
It was found that welding should be performed within a range satisfying the cycle (power frequency) and the opening time t ₆ : 5 to 30 cycles (power frequency).

[0031]

When the aluminum-coated steel wire is welded according to the invention of the present application, the aluminum-coated layer at the joint portion of the wire is melted and removed, and then welded, so that the welding strength is excellent, and the aluminum-coated steel wire is welded. The layer remains almost the same except for the welded part and retains the anticorrosive effect, and a disordered part of the coating layer inevitably occurs at the weld corner, but aluminum for steel Due to the sacrificial anode effect, the corrosion resistance, strength, appearance, etc. are hardly affected. Further, it is possible to obtain a special effect that a relatively smooth welded body can be obtained with almost no burr.

[Brief description of drawings]

FIG. 1 is an enlarged view of an electrode portion of a welding machine according to the present invention.

FIG. 2 is a sectional view taken along the line YY in FIG.

FIG. 3 is a welding work process diagram in the invention of the present application.

[Fig. 4] Change diagram of welding condition of aluminum-coated steel wire

FIG. 5 is a diagram showing the relationship between the overlapping thickness ratio and the shear strength at the intersection of the wire according to the invention of the present application.

[Explanation of symbols]

1, 2 Aluminum-coated steel wire 3, 4 Welding electrodes D ', D "Wire rod outer diameter D ₁ , D ₂ Steel wire diameter d ₁ , d ₂ Steel wire aluminum coating layer thickness H Welding work stroke

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshito Wakabayashi 9-1 Futaba-cho, Numazu-shi, Shizuoka Fujikura Electric Wire Co., Ltd. Numazu Factory

Claims (5)

[Claims] 1. When electric resistance welding is performed by intersecting aluminum-coated steel wires with each other, only the aluminum coating layer at the cross-contact portion is melted by primary energization, and after the steel wires come into contact with each other, secondary energization is performed. A method for welding an aluminum-coated steel wire, which comprises welding. 2. The aluminum-coated steel wire according to claim 1, wherein the primary energization has a large energizing current and a short energizing time, and the secondary energizing has a small energizing current and a long energizing time. Welding method. 3. An aluminum-coated steel wire having a steel wire diameter of D ₁ and an aluminum coating layer thickness of d ₁ , and an aluminum-coated steel wire having a steel wire diameter of D ₂ and a coating layer thickness of d _2. When cross-welding with 2, welding work conditions include welding work stroke H: 3 to 6
mm, applied pressure: 1 to 5 kg / cm, initial pressurization time t ₁ :
5 to 60 cycles (power frequency), the primary energizing time t _2:
5 to 30 cycles (power frequency), primary energizing current: 30
00 to 15,000 amperes, cooling retention time t _3: 0~3
0 cycles (power frequency), the secondary current supply time t _4:. 10 to
60 cycles (power frequency), secondary current: 1000
5000 amps, retention time after the energization t _5: 5~30
Cycle (power frequency), the opening time t _6: By welding range satisfying 5-30 cycles (power frequency), the thickness A overlap before welding in the intersection of two coated steel wire
The relationship between [A = D ₁ + D ₂ +2 (d ₁ + d ₂ )] and the overlapping thickness B after welding is 88 / 100A ≧ B ≧ 68/10
A welding method for an aluminum-coated steel wire, characterized in that the deformation range is 0 A. 4. The method for welding an aluminum-coated steel wire according to claim 1, wherein an aluminum-coated steel wire having a purity of aluminum of 99.5% or more is used. 5. The space factor of aluminum is 10 to 50%.
5. The method for welding an aluminum-coated steel wire according to claim 1, wherein the aluminum-coated steel wire is used.