JPS623882A - Joining method for welding wire - Google Patents

Abstract

PURPOSE:To extremely facilitate a burr finishing work by making the burr at joining part smaller and thinner by joining with electrification for short time the electric energy having a big specifying range according to the wire diameter in the butt state of the welding wire in the pressure state of its each end face. CONSTITUTION:The welding wire 1, 1 in 0.8-2.4mm diameter are set to the clamp 2 at fixed side serving an electrode as well and the clamp 3 at moving side and abutted in the pressure state to the extent of each end face of the wire 1, 1 coming in slight contact with by actuating the clamp 3. With this state, the electric energy of 160-1,600watt/sec is passed to the wire 1, 1 for the short time of about 7-20m/sec according to the diameter thereof and the wire 1, 1 is joined by stopping the pressure after stopping the electrification with the pressure state. It is however preferable to perform said electrification of electric energy after pre-electrification of the wire 1, 1.

Description

[Detailed description of the invention] Field of industrial use] The present invention relates to a method for joining welding wires.

(Prior Art) Generally, wire for gas shielded arc welding is wound up on a reel or a pail and supplied to the user.The standard weight of the wire is 20 kg for the former + 20 kg for the latter.
It is 0-250Kg.

By the way, in mass production industries such as automobile manufacturing plants, welding wires having a diameter of 0.8 to 2.4 strokes are generally used.

However, in this case, if the reel or pail is replaced every time one reel or pail of welding wire is used up, the production line must be stopped each time the welding wire is replaced, which reduces productivity.

Therefore, in general, a method is adopted in which wire of a new pail is joined to the end of the wire of a reel or pail in use, so that wire is endlessly supplied to the welding part.

Such welding wires have conventionally been joined by butt welding (also referred to as slow butt welding or upset butt welding).

This upset butt welding will be explained with reference to FIG. S and FIG. 10.

First, as shown in FIG. S (a), welding wires 1, 1, which are two materials to be welded, are set in a stationary clamp 2 and a movable clamp 2, which also serve as electrodes.

After that, start the movable side clamp (electrode) 3 and see Fig. S (
Move the clamp 3 as shown in b) and wires 1 and 1.
Bring each end face into pressure contact.

Then, as shown in FIG. S (c), while pressurizing the wire 1, for example, a
Approximately 5 cycles of alternating current welding current is applied to the wire 1, and the temperature of the joint is raised using heat generated by the contact resistance and specific resistance of the wires 1, 1.

The energizing circuit of the welding machine, for example, as shown in FIG. 11, includes an AC power source 4, 5CR5, E+, and a welding transformer 7, which are controlled on/off by an energizing control circuit (not shown).

Thereafter, as shown in Figure S (d), the power supply to the wire 1 is stopped, and after continuing the pressure on the wire 1, the pressure on the wire 1 is stopped as shown in the same figure (e). .

[Problem that the invention seeks to solve]

However, in such upset butt welding, as shown in FIG. 12, the wire 1 is heated over a wide range of length, so a large amount of metal that softens when pressurized is extruded. A gap 1a is formed at the joint,
Moreover, since the temperature gradient is gentle, the layer 1a becomes thick.

By the way, when welding wires are joined in this way, after welding, the edges of the wire joint must be removed using a file or a grinder to make the joint approximately equal to the outer diameter of the wire.

That is, when the welding wire is used for arc welding, the welding wire 1 pulled out from the pile 12 (or pail) as shown in FIG. The arc 1 is sent to the welding torch 16 via the feed path 15 by the feed roll 14 of
7 to weld the member to be welded 18.

However, at this time, if the joint part of the welding wire is finished too thin, when the joint part is sent to the feed roll 14, the pair of feed rolls that were pressurized with a constant force 14 idles on the surface of the wire 1, the wire 1 is no longer fed, and subsequent welding work cannot be continued.

Further, a contact tip is attached to the tip of the welding torch 16 as shown in FIG. 14, and the wire 1 is sent out through the center hole 20 of the contact tip.

The center hole 20 of this contact chip 1 has a diameter of +0.1 mm+ to +0. It is processed to about 2mm.

Therefore, if the joint portion of the wire 1 is insufficiently finished, the contact tip may not be able to pass through the center hole 20, or the resistance during energization will be large, making it impossible to perform stable welding work.

Therefore, as mentioned above, the large cracks that occur at the wire joints are manually removed to make them equal to the wire diameter (±
(0.1 mm or less).

However, it is difficult to finish the wire joint part by hand so that it falls within a range of ±0.1 nun or less with respect to the wire diameter.

As a result, wire feeding problems often occur.

[Means for solving problems]

In order to solve the above problems, this invention has a diameter of 0.8~
Welding wires of 2.4 ml and 1 M are joined by applying electric energy of 160 to 1600 watt-seconds for a short time depending on the diameter of the wires with their respective end surfaces pressed against each other.

[Function] Heat concentrates near the contact surface of the wire, pinching the plastic deformation area due to pressure, and thinning the cracks that occur at the joint.

[Embodiment j] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing the wire bonding process of the first embodiment of the present invention.

First, as shown in the same figure (A), after setting the welding wire 1゜1 to the fixed side clamp 2 which also serves as an electrode and the movable side lamp 3, start the clamp 3 and as shown in the same figure (B). The end surfaces of the wires 1, 1 are butted together under pressure (the end surfaces of the wires 1, 1 may be in light contact with each other) as shown in FIG.

Then, a large welding current (electrical energy) is applied for a short time to the welding wire 1 while in this pressurized state as shown in FIG. After stopping, the pressurization is stopped and the wires 1, 1 are joined as shown in FIG.

The current application time in this case varies depending on the diameter of the wire 1, but according to experiments, good results were obtained when the current application time was in the range of 7 to 20 m5ec.

Moreover, the relationship between the wire diameter, the electrical energy supplied during energization, and the joining result (the energization time was 7 to 20 m5ec) was shown in FIG. 2 through experiments. In addition, each mark in the figure is an X-near 1j cut.

MU: Occurrence of burrs, O: Good, .: Central condition, Δ: Insufficient strength, ×: Peeling.

For example, Table 1 shows the relationship between electrical energy (watt seconds: W, S) and the difficulty of finishing for wires with a diameter of 1 or 2 mm.

Table 1 As can be seen from Table 1, if the electrical energy to the wire is too small, the strength of the joint will be low, and if it is too large, the crack will become large or splash will occur. Regarding the wire, the electrical energy is ``250 ~
Good results have been obtained in the range of 300 watts seconds.

In this way, good joining results can be obtained by applying electrical energy of 160 to 1,600 watt-seconds depending on the wire diameter for a short period of time (7 to 20 m5ec) while the end surfaces of the wires are butted together. .

In other words, by applying a large welding current for a short period of time, the conduction of resistance heat generation at the contact surface to the wire is reduced, heat is concentrated near the contact surface, and the plastic deformation area due to pressure is pinched, resulting in a joint. The particles that appear on the surface become smaller and thinner.

As a result, there are many cases in which the wire can be fed without finishing the edges of the joint, and even if it is finished, it can be finished by simply sanding it lightly with sandpaper.

However, in this method of welding by applying a large welding current for a short period of time, the condition of the contact surface of the wire affects the welding quality.

In other words, for wires with a diameter of 1.2 mm that are joined by applying a current of 250 to 300 watts for a short period of time, the respective joint strengths are determined when the butt surfaces of the wires are in surface contact and when they are in local contact. The passing rate and feeding test passing rate are shown in Table 2.

The joint strength pass rate is the percentage of wires that break at places other than the joint in a tensile test of the wire that includes the joint, and the feed test pass rate is the ratio of wires that break at places other than the joint when used for arc welding without any abnormality in the arc phenomenon. is the proportion consumed.

Table 2 As can be seen from Table 2, when the abutting surfaces are in surface contact, high pass rates are obtained for both the joint strength pass rate and the feed test pass rate.

However, 1. For example, when the wires are in local contact, such as when joining wires that have been cut with pliers, only the contact area may be excessively heated and melted, which may scatter as splash and cause defects in the joint. , the joint strength pass rate and the feed test pass rate also decrease.

FIG. 3 is a diagram for explaining the wire bonding process of the second embodiment of the present invention. This will be explained with reference also to FIG.

First, as shown in Figure 3 (I), set the welding wire 1.1 to the fixed clamp 2, which also serves as an electrode, and the movable clamp O, and then start the clamp 3 as shown in Figure 3 (B). Then, the end surfaces of the wires 1, 1 are butted together under pressure.

Then, as shown in FIG. 3(c), a welding current smaller than that during main energization is energized for a short time (preliminary energization) to the welding wire 1 in the pressurized state, and then as shown in FIG. 3(d), Preliminary energization is stopped while the pressurized state is maintained.

Thereafter, as shown in FIG. 3(e), a large welding current is applied to the wire 1 in the pressurized state for a short period of time, for example, 7 to 20+asec as described above (main energization).

Thereafter, as shown in FIG. 3(F), the main current supply is stopped while maintaining the pressurized state, and then, as shown in FIG. 3(G), the pressurization is stopped and the wires 1, 1 are joined.

In this way, after performing preliminary energization, a large welding current is applied for a short time (main energization).

In addition to the effects of the above embodiments, good welding quality can always be obtained without being affected by the condition of the contact surface of the wire.

In other words, for the wires that were joined by performing two-step energization (pre-energization and main energization) in this way, the joint strength pass rate and transmission were determined for the cases where both abutting surfaces of the wires were in surface contact and when they were in local contact. Table 3 shows the passing rate of the salary test.

Table 3 As can be seen from Table 3, high joint strength pass rates and feed test pass rates were obtained in both surface contact and local contact cases.

Moreover, as can be seen from the comparison with FIG. 4 and FIG. 10-, the amount of electrode movement is small, that is, the welding allowance is reduced.

In this way, in any of the above embodiments, the burr produced at the wire joint is small and thin, making it easy to finish the burr removal.

Next, an example of a welding machine that performs energization control according to the second embodiment will be explained with reference to FIG. 5.

The welding current supply circuit in this welding machine includes an AC power supply 21
A transformer 22 boosts the AC voltage from the

This boosted AC voltage is converted into a high DC voltage by a full-wave rectifier 23.

Then, the DC high voltage obtained from the full-wave rectifier 23 is supplied to the pre-energization capacitor 25 via the pre-energization charge control 5CR 24, and also to the main energization capacitor 27 via the main energization 5CR 2G.

Then, the voltage accumulated in the pre-energizing capacitor 25 is supplied to the welding lance 30 via the pre-energizing capacitor 28, and the voltage accumulated in the main-energizing capacitor 27 is supplied to the welding lance 30 via the main-energizing capacitor 29, Clamp (electrode) the DC low voltage generated on the secondary side of this welding transformer 30
2 and 3, a direct current welding current is supplied to the wire 1.

On the other hand, in the welding current supply control section 31, when the charging start push button switch 32 is pressed, the charging voltage setting device 33 is set to the 5CR for preliminary energization charging via the driver 34 and the driver 35.
24 and the main energization charging 5CR 26 are turned on to start charging the preliminary energization capacitor 25 and the main energization capacitor 27.

The charging voltage setter 33 sets the charging voltage of the pre-energization capacitor 25 and the main energization capacitor 27 to the set pre-energization charging voltage and the set main energization charge voltage set by the pre-energization setting device 36 and the main energization setting device 37. When the charging voltage is reached, each 5CR24 and 5CR2S is controlled to turn off,
Charging to each capacitor 25 and 27 is stopped.

Thereafter, when the starting push button switch 38 is pressed, if the timer 39 receives a charge completion signal from the charge setting device 33, it controls the pre-energization 5CR 28 to be turned on via the driver 40.

As a result, the discharge voltage from the pre-energizing capacitor 25 is applied to the welding transformer 30, and a pre-energizing welding current is applied to the wires 1, 1 via the clamps 2, 3.

After that, the timer 3 days controls the preliminary energization 5CR28 to turn off when a predetermined time has elapsed from the start of the preliminary energization, and ends the preliminary energization.

Then, when a predetermined period of time has elapsed after the start of preliminary energization, the timer 3 days controls the main energization 5CR 29 to be turned on via the driver 41.

As a result, the discharge voltage from the main energization capacitor 27 is applied to the welding transformer 30, and the main energization welding current is applied to the wires 1, 1 via the clamps 2, 3.

Thereafter, the timer 3S controls the main energization 5CR 29 to turn off when a predetermined period of time has elapsed from the start of the main energization, thereby ending the main energization.

That is, as shown in FIG. 6, at one time point 1. ) to start preliminary energization and apply a small welding current. This preliminary energization ends at time t1.

Thereafter, a time point t when a predetermined time T has elapsed from the start of preliminary energization
At step 2, main energization is started and a large welding current is applied. This main energization ends at time t3.

Incidentally, although the timing of starting energization of the five wires is controlled by a timer, for example, the amount of movement of the movable clamp may be detected and the timing may be controlled based on the detection result. However, since it is on the moving side, an expensive device is required to accurately detect the amount of movement, so there is no practical problem in using a timer as in this embodiment, and it is advantageous in terms of configuration and cost. It is.

Next, timing control of preliminary energization and main energization will be explained.

As mentioned above, pre-energization is performed by shaping the unevenness of the cut cross section of the wire and adjusting the push distance (
This is to reduce the amount of heat input (upset cost) as much as possible, and to obtain stable welding quality with less occurrence of flash.

In this case, what are the factors that determine the time interval between preliminary energization and main energization?

■ Temperature rise and increase in electrical resistance at the contact part (butt part) and its vicinity due to preliminary energization ■ Minimum time required for electrical interlock of preliminary current and main current (■ Time for magnetic energy storage effect of welding transformer Dependence (magnetic energy changes over time).

Disappear) ■) Working time etc.

Among these, ■～■ do not have a big effect on welding performance (
, (j) are the main factors.

That is, the contact area and its vicinity instantaneously reach a high temperature of 1500 to 2000°C due to preliminary energization, but most of it becomes spatter and scatters, and the temperature drops to 150 to 200°C after lapse of L seconds from the start of preliminary energization. Moreover, the electrical resistance value of the wire is reduced to such an extent that it does not pose a problem with the contact resistance of the contact portion.

However, since the preheating effect and magnetic energy storage effect due to preliminary energization are time-dependent, it is desirable that there be no variation in the time interval between preliminary energization and main energization.

The time interval between preliminary energization and main energization is time t as shown in Fig. 6, and the time of preliminary energization is 5 to 7 m5.
ec, but it is difficult to confirm that preliminary energization is complete, so
As described above, the start timing of main energization is controlled by the time from the start of preliminary energization.

The timer that controls the time from the start of preliminary energization to the start of main energization can be set within the range of 0.2 to 2.0 seconds, and it is desirable that the 1-meter return accuracy be within ±1%.

Next, the relationship between the wire diameter and the electric energy value supplied during preliminary energization and main energization will be explained.

First, the electrical energy (preliminary energization value) during preliminary energization and the electricity during main energization of a wire with a diameter of 0.8 to 2.4 mm (this diameter is the same as that commonly used in the past). According to experiments, the relationship between energy (main energization value) and bonding results is as shown in FIGS. 7 and 8. In addition, each mark in both figures is burr fusion, M: large burr generation, o: good, ・: center condition, Δ: insufficient strength, X
：Means peeling.

As can be seen from this experimental result, the diameter is 0.8 to 2.4 mm.
For wires, the current value per wire is 16 depending on the wire diameter.
Good results are obtained with voltage energies between 0 and 1600 watt-seconds.

If this is determined by numerical calculation, it will be as follows.

First of all, when joining wires of diameters 1 and 2, for example, the ends of the wires must be melted and joined by approximately 0.1 om each, or in fact, a heat dissipation and pressure welding method is required, so one side of the wire must be 1.
It is estimated that 0+u+.

Therefore, the amount of heat to melt the wire 1.01 made of iron is determined.

First, what is the weight W of one side?

W=0.6' πX7.8XIX10S=8.8X1
The heat of fusion of 0 sg iron is 354 cal/g = 1475
W, s/g, so the tips of the left and right wires are each 1
, the amount of heat Q required to melt 0 mm is.

Q=8.8X10-' XL475X2==26W, S
becomes.

If the main energization time is 1On+, sec, the time from the start of 1 energization to the maximum value is about 5 rssec, so the power P required for welding is.

P=26W, 515X10-'5ec=5200W.

Here, the contact resistance when the wires are butted together is 350
In addition, the protrusion length during welding (clamp spacing) is approximately 6 mm, and the specific resistance of the wire is 1
100 x 10-' ohms, and the impedance of the welding machine itself is about 300 x 10-' ohms, so the total impedance R is: R = 1750 x 10-' ohms.

Therefore, the welding current ■ is I = (P/R)" = (5200/350X10-")
^→The output of the welding machine is 3900A.

I” R=3900”X1750X10-@=267
It becomes 001.

From the above, the electrical energy Q is 5 X for the total time of main energization.
Since 2 = 10m5ec.

Q = 26700 x 10 x 10-' = 2
It becomes 67W, S.

Also, the preliminary energization can be set to about 1/10 to 1/20 of the main energization, so for wires with a diameter of 1 to 2 mm.

Pm2O3 degree r = (500/350 x 10-”) 12
0OAI'R=1200"X1750X10-@=
25001Q=2500X10X10-'IN, 5=2
51. It becomes S.

Next, 1. For example, when joining wires with a diameter of 2.4 mm,
The tips of the wires are melted and joined by approximately 0.1 mm+ each, but in reality, heat dissipation and pressure welding are required, so it is estimated that each side is 1.01 mm.

Therefore, the amount of heat required to melt the wires l and Oim made of iron is determined.

The weight W on one side is.

W=1.22 πx7.8xlxlo-”=35.3
x], 01g.

The heat of melting iron is 354 cal/g = 1475W,
s/g, so the tips of the left and right wires are 1 and 0, respectively.
The amount of heat Q required to melt +n+o is: Q = 35.3 x 1o-' x 1475 x
105W out of 2, S.

If the energization time for 9 wires is 10m5ec, the time from the start of 1 energization to the maximum value is approximately 511Isec, so the power P required for TM connection is: p = 10515 x 10-' = 21000W
becomes.

Here, the contact resistance when the wires are butted together is 90X
The protrusion length during welding (clamp spacing) is approximately 6 mm, and the specific resistance of the wire is 270.
X 10”@Ω, the impedance of the welding machine itself is approximately 30
0 x 10-''Ω, so the total impedance R is.

R = 6sOXto-@Ω It is.

Therefore, the welding current ■ is.

I = (P/R) gift = (210oO/90 x 10
-@) ” = 15300A Therefore, the output of the welding machine is.

1” R=153002X660X10-”=1550
It becomes 0011.

From the above, the electrical energy Q is 5 X for the total time of main energization.
Since 2 = lomsec.

Q = 155000 x 10 x 10-' = t
= 1550s, becomes S.

Further, the preliminary energization can be set to about 1710 to 1/20 of the main energization, so for a wire with a diameter of 2°4no++.

P = about 2000w I = (2000/90 X to-”) Pupil-+
470OAT"R=47002X660X10-"=
], 45001i1Q = 14500 X 10
10-'W,S = 14'5W,S.

In the above embodiment, a welding machine that uses a capacitor to apply a large welding current for a short period of time is described, but it is possible to directly apply a large welding current for a short period of time without using such a capacitor charging method. It can also be done.

(Effect of the invention J As explained above, according to the present invention, since the wires are joined by applying a large welding current for a short time, the cracks at the joint are small and thin, making the finishing work extremely easy. .

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the wire joining process of the first embodiment of the present invention, Fig. 2 is a diagram showing the energization value, wire diameter, and the state of the joining result, and Fig. 3 and 4 are the diagrams of the invention. An explanatory diagram showing the wire joining process of the second embodiment, a timing chart diagram showing the relationship between the electrode movement amount and welding current, and FIGS. 5 and 6 also illustrate the thread threading control of the second embodiment. A block diagram showing an example of a welding machine and a timing chart for explaining its operation; FIGS. 7 and 8 are diagrams showing preliminary energization values, main energization values, wire diameters, and welding results. FIGS. S and 10 are explanatory diagrams showing the joining process of a conventional wire joining method, and timing charts showing the relationship between electrode movement amount and welding current to provide the explanation. FIG. 11 is a circuit diagram showing an example of a welding current supply circuit that similarly controls the energization. Fig. 12 is an explanatory diagram for explaining the temperature distribution and welding results during welding, and Figs. 13 and 14 are configuration diagrams and cross-sectional views of essential parts for explaining the usage conditions of welding wire in arc welding. It is. 1... Welding wire 2... Fixed side clamp 3... Moving side clamp 25... Preliminary energization capacitor 27... Main energization capacitor, 7. j Figure 1 Clamp Figure 9 Figure 10

Claims (1)

[Scope of Claims] 1 A welding wire having a diameter of 0.8 to 2.4 mm is subjected to an electric current of 160 to 1600 watt seconds depending on the diameter of the wire, with each end face of the wire butted under pressure. A method for joining welding wires, which is characterized by applying energy for a short period of time to join the welding wires. 2 After pre-energizing the welding wire, the above 160-1
The method for joining welding wires according to claim 1, wherein 600 watts of electrical energy is applied.