JP2732339B2 - Electric resistance welding method of aluminum coated steel wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, to manufacture a wire mesh or the like by an electric resistance welding method using a metal wire, a steel wire alone, a galvanized steel wire in which steel wire is galvanized, or a stainless steel wire is used. However, although a strong welding can be obtained with steel wire,
Since red rust easily occurs, plating and surface treatment with paint are required.If the galvanized steel wire is too thick, the steel and zinc of the core wire are alloyed at the time of welding to reduce welding strength, corrosion resistance and appearance In addition, the welding strength of the stainless steel wire was varied due to heat influence, or the stainless steel wire was discolored and the corrosion resistance was changed.

[0003] Therefore, attempts have been made to use an aluminum wire or an aluminum alloy wire having good corrosion resistance and appearance. However, these wires have extremely high conductivity, so that the amount of current flow is excessive, which is inconvenient in terms of equipment. Even if welding is carried out with a large current, it is very difficult to obtain sufficient welding strength because it is very easily oxidized.

However, in recent years, an aluminum-coated steel wire in which an aluminum coating layer has been applied to the surface of a steel wire has a more stable surface layer than a galvanized steel wire or the like, and is not only mechanically strong but also has a high corrosion resistance. Since it has enough, it has come to be widely used for fences, animal breeding cages, bird cages, and the like.

[0005]

As a commonly used aluminum-coated steel wire, a high-purity aluminum having an aluminum purity of about 99.8 to 99.6% is hot-extruded onto the steel wire and melted. It is coated with a cladding layer by plating or tape, or coated by powder sintering method, etc. and finished to a specified outer diameter.Electric resistance welding is performed on the intersection using such aluminum-coated steel wire. When aluminum and steel are used, electric resistance (Al = 2.8 μΩ-cm, Fe = 10 μΩ-c
m) is different by several times or more, so that current leakage is large in the ordinary welding method, it is difficult to obtain good welding, and aluminum changes into oxide immediately after melting, so any welding Even with experience in technology, the aluminum coating layer on the surface of the steel wire melts down and the steel wire part is exposed, reducing the corrosion resistance near the cross weld or the aluminum coating hindering the joining Problems that only low welding strength can be obtained, aluminum burrs are generated and the appearance is deteriorated, and when animal cages or bird cages are used, animals may be damaged by burrs etc. was there.

[0006]

As one means for solving the above-mentioned problems, the applicant of the present invention has proposed using a coated steel wire having a large resistance value of an aluminum coating layer as disclosed in Japanese Patent Application No. 3-2541.
No. 82. That is, purity 9 on steel wire
9.5% or less of aluminum or Fe 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 to 1.5%.
~ 2.0 wt%, Mg 0.5 ~ 2.0 wt%, Mn 0.5 ~
By using an aluminum-coated steel wire with 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 cleaner appearance and higher welding strength. Apart from this method, as a result of intensive studies to solve the above problems, the invention of the present application, the bonding strength and 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 was related to the welding work stroke and the pressing force, and the aluminum coating layer was instantaneously softened with a large current under a constant pressing force and pressurizing time,
The primary energizing current value to be melted, and the optimal energizing time and holding time for supplying and joining the secondary energizing current value as a welding current to the steel cores in the molten aluminum liquid layer after melting, Is selected so that the relationship between the overlap thickness A before welding and the overlap thickness B after welding at the intersection of steel wires falls within the range of 88 / 100A ≧ B ≧ 68 / 100A. Welding was performed.

That is, when welding is performed, the current is divided into two stages, primary current and secondary current, so that the aluminum coating layer of the steel wire is melted and removed only at the portions where the steel wires come into contact with each other. Stopped to get a strong joint between the steel wires. In addition, when the same two-step current welding was performed using the coated steel wire described in Japanese Patent Application No. 3-254182, the same good appearance as in the case of the aluminum-coated steel wire could be obtained. However, no special value was found for adoption in terms of manufacturing cost.

[0008]

As shown in FIG. 2, aluminum-coated steel wires 1 and 2 having wire diameters of D 'and D ", respectively, intersect and overlap on a lower electrode plate of a welding machine in which welding electrodes are arranged vertically. When performing electrical resistance welding by placing
First, 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 pressurizing time is set to 5 to remove the aluminum jacket of the joint portion by melting. A pressure of 1 to 5 kg / cm ² is applied during 60 cycles (power frequency),
3000 to 15000 amps as the primary current
The aluminum sheath is melted by energizing for up to 30 cycles (power frequency) to cool and maintain the steel wires in contact with each other. Subsequently, 1000 to 5 as a secondary conduction current
000 amps are energized for 10 to 60 cycle times to join the steel wires together, held for 5 to 30 cycle times and then released to complete the welding operation. The welding state at this time is as shown in FIG.

By performing the welding operation in this way, a large current is supplied in a short time as the primary current, so that only the aluminum coating layer at the joining portion can be quickly melted and removed, and the other aluminum coating layer portions can be removed. The steel wires were able to be efficiently and firmly joined together without causing any press or welding scratches, and a welded product of an aluminum-coated steel wire having a good appearance was obtained.

Here, the limitation of the welding stroke is that if the stroke is too long, the response of the electrode at the spot is slowed, and the contact point between the electrode and the aluminum coating layer is damaged, so that the speed of the spot is improved. This is to reduce the impact at the time of pressurization and smoothly enter the initial pressurization step. If the initial pressurization time is too short, the wire or welder will be easily impacted, and if it is too long, the hitting speed will decrease.If the pressing force is too small, the contact of the wire will be good. This is because the appearance abnormality of the surface of the aluminum layer and the occurrence of welding burrs due to sparks increase.

The primary conduction current is defined because aluminum has a small electric resistance and escapes without heat when the current is small, and melts when too large.
If the primary energizing time is too short, the aluminum layer does not melt, and if it is too long, even the steel wire may be blown.

The secondary energizing time and the secondary energizing current are limited because if the energizing time is too short or the energizing current is too small, the steel wire will not be joined, or if the energizing time is too long or if the energizing current is too small. If the steel wire is too large, the steel wire will be melted or deformed.

The reason for the two-stage energization is that in order to melt and remove the aluminum coating layer having a low electric resistance and a high thermal conductivity, it is necessary to energize a large current in a short time. This is because the strong welding of the competitors requires a small current since there is a risk that the heat generation will be excessive at a large current and the steel wire will be blown.

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

[0015]

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

Example 1 (Experiment No. 2) Welding work stroke: 3.0 mm, initial pressurization time: 1
5 cycle time, primary energization time: 5 cycle time,
Primary energizing current: 10000A, secondary energizing time: 15 cycle times, secondary energizing current: 2500A, holding time after energizing: 10 cycle times, welding force: 2.0kg / cm ² As a result of welding under the above set conditions, The change in the overlap thickness of the wire rod is 78%, no elution projections or burrs are found on the wire rod, the appearance is good, and the shear fracture strength of the weld is 32k.
g / mm ² .

Example 2 (Experiment No. 4) Welding work stroke: 4.0 mm, initial pressurization time: 1
5 cycle time, primary energization time: 5 cycle time,
Primary energizing current: 10000A, secondary energizing time: 15 cycle times, secondary energizing current: 2500A, holding time after energizing: 10 cycle times, welding force: 2.0kg / cm ² As a result of welding under the above set conditions, The change in the overlapping thickness of the wire was 70%, and the occurrence of elution protrusions and burrs of the wire was recognized, and a wire having a poor appearance was obtained.

Example 3 (Experiment No. 6) Welding work stroke: 4.0 mm, initial pressurization time: 1
5 cycle time, primary energization time: 5 cycle time,
Primary energizing current: 10000A, secondary energizing time: 15 cycle times, secondary energizing current: 2500A, holding time after energizing: 10 cycle times, welding force: 2.0kg / cm ² As a result of welding under the above set conditions, The change in the overlapping thickness of the wire rod is 75%, no elution projections or burrs are found on the wire rod, the appearance is the best, and the shear fracture strength is 35 kg.
/ Mm ² .

Example 4 (Experiment No. 17) Welding work stroke: 8.0 mm, initial pressurization time: 1
5 cycle time, primary energization time: 5 cycle time,
Primary energizing current: 10000A, secondary energizing time: 15 cycle times, secondary energizing current: 2500A, holding time after energizing: 10 cycle times, welding force: 2.0kg / cm ² As a result of welding under the above set conditions, The change in the overlapping thickness of the wire was 50%, and elution projections and burrs of the wire were observed, and a poor appearance was obtained.

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 energizing current: 10000A, secondary energizing time: 15 cycle times, secondary energizing current: 2500A, holding time after energizing: 10 cycle times, pressing force: 3.0 kg / cm ² As a result of welding under the above set conditions, The change in the overlapping thickness of the wire rod was 75%, no elution projections or burrs were found on the wire rod, the appearance was good, and the shear fracture strength was 34 kg / mm ^2.
Things were obtained.

The other examples are summarized in Tables 1 to 4 in which the results for each of the welding conditions, wire properties and welding properties are summarized. FIG. 5 shows the relationship between the shear strength and the overlap thickness ratio at the intersection of the wires based on the above.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

[0026] In addition, a mild steel wire such as SWRH8 shown in JIS 3505 is used as the steel wire of the wire rod. However, when hard steel wires are welded together, a quenching phenomenon occurs at the time of welding and satisfactory strength cannot be obtained. Therefore, if the welding is a combination of a hard steel wire and a mild steel wire, a welding strength having no problem in strength can be obtained.

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

From the above, it can be seen that a material which has a good appearance and can be put to practical use must be within the range of the region C in FIG.

Therefore, in order to achieve this, 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 of the aluminum-coated steel wires D' is D '. _1. Assuming that the thickness of the coating layer is d ₁ , the diameter of the steel wire which is the core of the other aluminum-coated steel wire D ″ is D ₂ , and the thickness of the coating layer is d ₂ , Thickness A before welding (A = D ₁ + D ₂ +2 (d ₁ +
d ₂ )] and the overlap thickness B after welding are 88/1
The welding operation needs to be performed according to the steps shown in FIG. 3 so as to fall within the deformation range of 00A ≧ B ≧ 68 / 100A. By doing so, the state shown in FIG. 4 is obtained and the coated steel wire is welded.

The welding operation conditions for satisfying the above requirements include welding operation strokes H: 3-6.
mm, pressure: 1-5 kg / cm, initial pressurization time t ₁ :
5 to 60 cycles (power frequency), primary energization time t ₂ :
5 to 30 cycles (power frequency), primary energizing current: 30
00 to 15000 amps, cooling holding time t ₃ : 0 to 3
0 cycle (power frequency), secondary energization time t ₄ : 10
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: 5 to 30 cycles is possible may be welded in a range satisfying (power frequency) it was found.

[0031]

When an aluminum-coated steel wire is welded according to the invention of the present application, the aluminum coating 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 coating is improved. The layer remains almost as it is except for the welded portion, and retains the corrosion-resistant effect, and a turbulent portion of the coating layer is inevitably generated at the weld corner, but the aluminum layer on the steel is inevitable. Has almost no effect on corrosion resistance, strength, appearance, etc. In addition, it is possible to obtain a special effect that a relatively smooth welded body can be obtained with almost no burrs.

[Brief description of the 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 line YY in FIG.

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

FIG. 4 is a change diagram of a welding state of an aluminum-coated steel wire.

FIG. 5 is a diagram showing the relationship between the overlapping thickness ratio at the intersection of the wires and the shear strength in the present invention.

[Explanation of symbols]

1,2 electrode D for aluminum coated steel wire 3,4 welding ', D "wire thickness H welding stroke of the outer diameter D _1, D ₂ the diameter d ₁ of the steel wire, d ₂ aluminum coating layer of the steel wire

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yoshito Wakabayashi 9-1 Futaba-cho, Numazu-shi, Shizuoka Fujikura Electric Wire Co., Ltd. Numazu Plant (56) References JP-A-63-68277 (JP, A) JP-A Sho 57-159276 (JP, A) JP-A-6-63761 (JP, A)

Claims (5)

(57) [Claims] When performing electrical resistance welding across aluminum-coated steel wires, only the aluminum coating layer at the intersection contact portion is melted by primary energization, and after the steel wires come into contact, secondary energization is performed. A method for welding aluminum-coated steel wire, characterized by welding. 2. The aluminum-coated steel wire according to claim 1, wherein the primary energizing increases the energizing current and shortens the energizing time, and the secondary energizing decreases the energizing current and prolongs the energizing time. Welding method. 3. An aluminum-coated steel wire having a steel wire diameter D ₁ and an aluminum coating layer thickness d ₁ , and an aluminum-coated steel wire having a steel wire diameter D ₂ and a coating layer thickness d _2. When cross-welding with No. 2, welding work conditions include welding work stroke H: 3-6.
mm, pressure: 1-5 kg / cm, initial pressurization time t ₁ :
5 to 60 cycles (power frequency), primary energization time t ₂ :
5 to 30 cycles (power frequency), primary energizing current: 30
00 to 15000 amps, cooling holding time t ₃ : 0 to 3
0 cycle (power frequency), secondary energization time t ₄ : 10
60 cycles (power frequency), secondary current: 1000
5000 amps, retention time after the energization t _5: 5~30
Cycle (power frequency), opening time t ₆ : By welding within a range satisfying 5 to 30 cycles (power frequency), the overlap thickness A before welding at the intersection of both coated steel wires
The relationship between [A = D ₁ + D ₂ +2 (d ₁ + d ₂ )] and the overlap thickness B after welding is 88 / 100A ≧ B ≧ 68/10.
A method for welding an aluminum-coated steel wire, characterized in that the welding is performed within a deformation range of 0A. 4. The method for welding an aluminum-coated steel wire according to claim 1, wherein an aluminum-coated steel wire having an aluminum purity of 99.5% or more is used. 5. The space factor of aluminum is 10 to 50%.
The welding method for an aluminum-coated steel wire according to any one of claims 1 to 4, wherein the aluminum-coated steel wire is used.