JPH0669596B2 - Link chain upset welding method - Google Patents

Description

The present invention relates to a welding method for upset welding a link chain of a structural alloy steel tire chain.

"Prior Art" When driving safely on snowy roads, it is necessary to install tire chains and spiked tires to prevent vehicle slippage. However, recently, a dust pollution problem caused by being scraped off from a road surface by a spike tire has been raised, and the spike tire tends to be restricted and prohibited from being used.

On the other hand, the need and importance of a tire chain has been recognized due to the occurrence of a serious accident in a tourist bus when the road surface freezes.However, a tire chain made of mild steel wire that fits the tire of a large bus that weighs about 15 tons is , About 42kg per wheel
It is difficult for a single driver to handle the chain because of the weight of, and there are inconveniences such as mounting a tire chain for a single tire on a double tire.

"Problems to be solved by the invention" Weight reduction (cross-sectional area ratio 2/3) by using a material with a smaller wire diameter (for example, diameter 5 mm → 4 mm, 10 mm → 8 mm) than the conventional tire chain without degrading the performance of the tire chain. It is necessary to do the following), but this cannot be solved only by improving the manufacturing method,
It is necessary to replace with a material having high mechanical properties, high impact resistance and fatigue resistance, and low low temperature brittle transition temperature.
However, from the viewpoint of cost, do not use expensive materials such as nickel / chrome molybdenum steel, but use manganese steel, which is a relatively inexpensive material that has the above characteristics sufficiently and is easily bent and heat treated. Becomes

Structural alloy steel generally has a higher content of chemical components of carbon (C), silicon (Si), manganese (Mn) than mild steel wire rod [mild steel: C = 0.05 to 0.15%, Si = very small amount ~
0.15%, Mn = 0.25-0.60%, structural alloy steel: C = 0.17-0.
23%, Si = 0.15 to 0.35%, Mn = 0.90 to 1.50%], to weld this, after sending a preheating current to the weld part by the flash welding method, then sending a high heating current to generate a spark,
Carbon, silicon, manganese, and other impurities in the weld material were scattered and removed, and sufficient Joule heat for fusion was given, and then upset pressurization was not possible to complete welding.

In this case, not only the loss of time during which the spark is generated, but also a large heating current is shunted 38 to the spine 36 of the link 35 shown in FIG. 7 as shown in FIGS. And softens. When one end of the link 35 is hooked on the hooking portion 91 and the pressing portion 92 is pressed from the other end to apply upset pressure, the link becomes elliptical (9th
(Fig. 8) shows that the shrinkage of the inner long dimension M is large (L> M), there is a slight unevenness in current flow due to the condition of the surface of the wire to be processed, and there is a shift in the operation timing of the pressurizing device. Long dimension L
Variation, the welded portion 37 was deformed and the weld strength was reduced.

If the link is divided into two (Fig. 11), the split flow will not occur, but automation of link welding becomes difficult. Further, the spark-like iron powder generated stains the mechanical device, resulting in poor insulation of the electric circuit, which causes many problems such as protection of the eyes of the worker, fireproofing of work clothes, and deterioration of the working environment. In addition, the weld 37
Since it becomes close to pure iron due to the flash action, damage due to strength reduction during twisting after the welding process of the grounding part of the tire chain (cross chain), and deterioration of mechanical properties after carburizing heat treatment due to surface hardening In order to compensate for this, a large welding peak must be left, which makes it unsuitable for a tire chain, which complicates the mechanical structure and requires DC welding, resulting in an expensive device.

Welding of the structural alloy steel by the upset welding method,
Complete melting unless a heating current higher than that of mild steel welding (30 to 40% increase over mild steel (mild steel wire: 150 to ^{200 A} per 1 mm ² cross section, alloy steel wire: 250 to 300 A per 1 mm ² cross section)) Welding must be completed in a short time in order to prevent the link 35 from being deformed due to the back partial flow, but the contact resistance Joule heat increases as the pre-pressurization decreases due to the resistance welding method. , The heating current could be reduced (same as mild steel wire or increased by 10%).

When welding is completed with the high heating current required for fusion connection, oxygen in the air and enzymes in the material react with carbon in the molten metal heated to 1500 ° C or more to generate carbon dioxide gas, which causes iron and iron If silicon, manganese, etc. oxidize to become impurities, and continue to apply pressure with pre-pressurization, feather-like burrs will appear
33 (Fig. 10), impure gas and impurities remain in the weld, coarsening and weakening the strength, and in extreme cases, the fracture surface becomes bluish and rough, and Figs. 12 and 13 As shown in Fig. 14, the fracture occurred at the weld, or as shown in Fig. 14, at the boundary of the weld, the tensile strength became half or less of the material strength of the weld of the perfect weld link.

In this case, a difference in melting point temperature depending on the chemical component content of the material to be processed in both the first pressure and the second pressure which are pressure-operated by the cam, the unevenness of the electric current due to the surface of the material and the contact portion state of the electrode, and dirt, There is a difference in the time taken to reach the melting point temperature due to the shape of the cut surface of the weld and dirt. At this time, if a constant pressurizing operation is applied and the temperature rises quickly, the welded part becomes an overheated structure and in some cases melts and falls off, and if the rise of the temperature is slow, incomplete welding results and variations occur. That is, when the required pressurization is too large, the heated welded portion is largely extruded to the outside, forming a large weld crest and causing a decrease in the strength of the welded portion. Further, if the required pressing force is too small, oxidized impurities may remain in the welded portion, leading to a decrease in the strength of the welded portion. In addition, the responsiveness to pressure may be insufficient and the welded portion may become molten metal and fall off. There was a drawback.

"Means for Solving the Problem" The present invention provides a first timer for a welded portion of a structural alloy steel link chain that is positioned between a fixed electrode and a movable electrode that sandwich the welded portion, via a foot switch. The step of activating the movable electrode for clamping by the time-delayed operation to continue the clamp pressurization, and the time-deactivated operation of the second timer by the time-up of the first timer, and the upset of the weak welding force by the operation of the upsetting pressurizing cylinder. The step of performing the first pressurization, the third timer and the fourth timer are simultaneously actuated after the time-up of the second timer, and the strong first heating current is applied to the welded portion for a short time by the timed operation of the third timer, Raising the temperature of the welded portion by the first heating current due to the contact resistance having a large cross section and the specific resistance of the link chain material due to the upset first pressurization; Switching the first heating current to a weak second heating current after the time-out of the third timer and continuing to energize the welded portion, and ending the upset first pressurization after the time-up of the fourth timer, and Upset second pressurization stronger than the upset first pressurization, the second heating current is terminated through a limit switch, and the welded part is upset second pressurized until the fifth timer which operates at the same time expires. The configuration including the forging step and the step of ending the upset second pressurization and the clamp pressurization by the time-up of the fifth timer is a means for solving the above problems.

[Operation] Welding of the link where the welded part of the link is clamped by the fixed and movable electrodes, and the upset first pressurization is performed by operating the cylinder for upset pressurization, and the hardness decreases in proportion to the heating degree of the power device. The pressure applied to the joint is good and the pressure of the joint is increased by a constant pressure to move the movable pressurizer in two steps, weak and strong, to form a connection crest in the welded part, and By utilizing the fact that both ends are pushed outward, the inner length of the link shrinks, and the limit switch is activated before the welding is completed to turn off the heating current. It is possible to make the amount of heat and the size of the weld mountain and the inner long dimension of the link constant.

[Embodiment] An embodiment of the present invention will be described with reference to FIG. 1. An air source 1 such as a compressor and a branching portion 2 of a pipe are connected to each other through an air filter 3 and an automatic lubricator 4 by a pipe. First, second and third solenoid valves 10, 11 and 12 are connected to the branch portion 2 via first, second and third pressure reducing valves 6, 7 and 8, respectively. First solenoid valve 10
One of the cylinders 14 and one of the front ends of the pair of cylinders 14, and the other of the first solenoid valve and each of the rear ends of the cylinder 14 are connected by pipes. Further, each piston 16 connected to a pair of movable electrodes 15 for clamping is housed in the cylinder 14 so as to be able to move back and forth, and a pair of fixed electrodes 17 facing each movable electrode 15 is provided. . A movable pressurizing unit provided so as to advance and retreat facing the fixed pressurizing unit 18 installed on one side of the fixed electrode 17.
The piston 20 connected to 19 is replaced with the cylinder 21 for upsetting.
It is housed inside so that it can move back and forth.

One side of the second solenoid valve 11 and the front end of the upsetting cylinder 21 are connected to each other, and the other side of the second solenoid valve and the rear end of the cylinder 21 are connected to each other by piping. 3 Connect the solenoid valve 12 with piping. In order to adjust the forward position of the movable pressurizing unit 19, a limit switch 22 for turning off the heating energization is provided on the secondary side of the welding transformer 25 provided facing the movable pressurizing unit 19 so as to be movable for clamping. An electric power device 23 that connects the fixed electrodes 15 and 17 and heats the welding portion 37 of the link 35 by applying electricity
And a pair of thyristors on the primary side of this welding transformer 25.
The ignition circuit 27 is connected through the thyristor switch 26 for controlling the heating current formed by the SCR, the resistor and the capacitor C,
An ignition circuit transformer 29 is provided between the ignition circuit 27 and the power supply 28.

Two variable resistors 30 and 31 for adjusting the secondary side current of the welding transformer 25 in two levels of strength and weakness are connected in parallel to the ignition circuit 27, and the fifth relay piece 51a having a closed contact and the open contact are provided. 5th relay piece 5
An adjusting circuit 32 is formed by 1b and the fourth relay piece 50a having an open contact. In addition, as shown in FIG.
0'and 31 'may be connected in series.

Next, the sequence circuit of FIG. 2 will be described.
A main switch 45 and a pair of fuses 44 are connected to a control circuit 42 connected to the control power sources U and V, and a pilot lamp 43 is connected in parallel to the control circuit 42. A foot switch 46, a third branch 70, a ninth relay piece 55a having a closed contact, and a first relay 47 are connected to the control circuit 42, and a first relay piece 47a having an open contact is connected.
And a fourth branch 71 connected to the branch 70 and a ninth closed contact
The relay piece 55b and the first timer 61 are connected.

Between the fourth branch portion 71 and the control circuit 42, there is an eighth closed contact point.
The relay piece 54a, the second relay 48, and the first timer piece 61a
The fifth branch 72 and the second timer 62 are connected to each other, the fifth branch 72 is connected to the eighth relay piece 54b and the third relay 49 which are closed contacts, and the second timer 62a is connected. And the sixth branch 73 and the third timer 63 are connected. Further, the sixth
The branch portion 73, the seventh relay piece 53a having a closed contact, and the fourth relay 50 are connected, and the sixth branch portion 73 and the fourth timer 64 are connected.

A third timer 63a and a fifth relay 51 are connected between the fourth branch unit 71 and the control circuit 42, and a fourth timer piece 64a, an eighth relay piece 54C having a closed contact, and a sixth relay. 52 is further connected, and further, the limit switch 22, the eighth branch 75, the ninth relay piece 55c having a closed contact and the seventh relay 53 are connected, and the seventh relay piece 53b having an open contact and the first relay piece 53b. The ninth branch portion 76 connected to the eighth branch portion 75 and the fifth timer 86 are connected, and further, the fifth timer piece 65a, the eighth relay 54 and the ninth relay 5 are connected.
5 are connected in parallel.

Further, in parallel with the control circuit 42, a second relay piece 48a having an open contact and the first solenoid valve 10 for clamp pressurization, and a third relay piece 49a having an open contact and a second solenoid valve 11 for upset first pressurization, The sixth relay piece 52a having an open contact and the third solenoid valve 12 for upset second pressurization are connected to each other.

Next, the operation of this embodiment will be described. First, when the main switch 45 is turned on and the control circuit 42 is energized, one end of the link 35 positioned between the clamping electrodes 15 and 17 is fixed to the fixed pressurizing portion 18. When the foot switch 46 (FS) is turned on, the first relay 47 is activated to turn on the first relay piece 47a, the foot switch 46 is held by itself, and the first timer 61 (T1) is timed. Start operation. Further, when the second relay 48 is activated and the second relay piece 48a is turned on, the first solenoid valve 10 for clamping is switched to move the movable electrode connected to the piston 16 in the cylinder 14.
15 is moved forward to clamp both end pieces 34 of the link 35 to start clamping pressure.

When the first timer 61 (T1) times out, the first timer piece 61a is turned on, the second timer 62 (T2) for upsetting first pressurization starts the time-delayed operation, and the third relay 49 is activated. 3 Relay piece 49a is turned on to switch the second solenoid valve 11, the movable pressing portion 19 is moved forward by the operation of the cylinder 21, and the upset first pressurization (40-60% strength of the second pressurization described later). To start. The ring 35, which is weakly upset by the movable pressurizing unit 19 moved forward by the operation of the cylinder 21, is first pressed by the upset first pressing force until the time of the second timer 62 (T2) expires.

When the second timer 62 (T2) times out, the third timer 63 (T3) and the fourth timer 64 (T4) start the time-delaying operation at the same time, and the operation of the fourth relay 50 causes the opening of the fourth relay piece 50a. (Fig. 1) is turned on, and the ignition circuit 27 is turned on to the primary side of the welding transformer 25 by the voltage of the first variable resistor 30 via the fifth relay piece 51a which is the closed contact of the fifth relay 51. Ignition of thyristor switch 26 through a higher primary voltage welding transformer
The power device 23 on the secondary side of 25 is energized, and this movable / fixed electrode is
A strong first heating current X (for example, 250 to 300 A per 1 mm ² of the cross-sectional area of the alloy steel wire) is applied to the welded portion 37 of the link 35 through 15 and 17 as shown in FIG. Therefore, the welded portion 37 is heated to a high temperature by heating with a large current due to the large contact resistance of the cross section due to the weak upset first pressurization and the specific resistance of the link chain material until the third timer 63 (T3) NO time is up.

Then, even if the third timer 63 (T3) times out,
The fourth timer 64 (T4) is in operation, the fifth relay 51 operates, the fifth relay piece 51a, which is a closed contact, is turned off, and the fifth relay piece 51b, which is another closed contact, is turned on. 2 variable resistors 31
The lower primary voltage due to the voltage is applied to the primary side of the welding transformer 25 via the thyristor switch 26, and the first heating current X
The second heating current Y, which is weaker by 40 to 60%, is applied to the link 35.
Very short time for this strong first heating current X (0.15 to 0.2 seconds)
To the second heating current Y that is weak and immediately before the flash occurs to suppress the temperature of the molten metal that continuously rises to prevent overheating and melting dropout. It prevents the shunt 38 to the back of the link 35. This second heating current Y is applied to the limit switch 22.
It keeps energizing until (LS) is activated.

When the fourth timer 64 (T4) times out, the fourth timer piece 64a is turned on, the sixth relay 52 is activated, and the sixth relay piece 5 is activated.
2a is turned on to switch the third solenoid valve 12, and the cylinder 21 is switched to the upset second pressurization (for example, 25 to 35 Kgf per 1 mm of the cross-sectional area of the alloy steel wire), which is about twice as strong as the first upset pressure. On the other hand, when the link 35 is continuously pressed until the time of the fifth timer 65 (T5) is up, the welded portion 37 pushes out impure gas and impurities to the outside by the strong upset second pressing force to form the weld mountain 39. However, the inner length dimension L of the link is shrunk by that amount, and when the movable pressurizing section 19 moves forward to a certain position by the operation of the cylinder 21, the limit switch 22 (LS) operates, the seventh relay 53 operates, and the closed contact is closed. The seventh relay piece 53a is operated to turn off the fourth relay 50, and the power supply to the primary side of the welding transformer 25 by the thyristor switch 26 is cut off to end the heating. At the same time, the fifth timer 65 (T5) starts the timed operation via the seventh relay piece 53b, which is the other open contact, and during the set time of the fifth timer 65, the welded portion 37 of the link 35 is
Is forged with a strong upset second pressure by the cylinder 21 to forge the molten metal.

When the 5th timer 65 (T5) times out and the 5th timer piece 65a turns on, the 8th relay 54 operates and the 2nd relay 4
8, the third relay 49, the sixth relay 52 is turned off, the piston 16 returns and the movable electrode 15 retracts to release the nipping of the link 35, and at the same time, the ninth relay 55 operates and the ninth relay piece 55a, Five
5b and 55c are turned off, the foot switch 46 is turned off, the control circuit 42 returns to the original state, and all the operations are completed.

Below, Experimental example 1 and Experimental example 2 of this invention are shown.

Experimental Example 1 When manufacturing a cross chain link for a light vehicle having a material diameter of 4 mm Material standard component (%) = carbon (C): 0.18 to 0.23, silicon (Si): 0.15 to 0.23, manganese (Mn): 0.80 to 1.1
0, Chrome (Cr): 0.10 to 0.20, Boron (B): 0.0010
that's all.

The first timer (T1) and clamp pressure are omitted because they are pinching operations.

Upset 1st force 176kgf (14.0kgf / mm ² ) Upset 2nd force 330kgf (26.3kgf / mm ² ) 2nd timer (T2) 0.15 seconds 3rd timer (T3) 0.15 seconds 4th timer (T4) 0.25 seconds Energizing time of welding current 0.18 seconds (9Hz) 5th timer (T5) 0.80 seconds 1st heating current 3440A (274A / mm ² ) 2nd heating current 1960A (156A / mm ² ) Experimental example 2 Large sightseeing bus with material diameter 8mm In the case of manufacturing a cross chain link for use, the material standard component (%) is the same as in Experimental Example 1, and is omitted.

The first timer (T1) and clamp pressure are omitted because they are pinching operations.

Upset 1st force 800kgf (15.9kgf / mm ² ) Upset 2nd force 1440kgf (28.6kgf / mm ² ) 2nd timer (T2) 0.15 seconds 3rd timer (T3) 0.20 seconds 4th timer (T4) 0.35 seconds Energizing time of welding current 0.28 seconds (14Hz) 5th timer (T5) 1.50 seconds 1st heating current 14300A (284A / mm ² ) 2nd heating current 7800A (155A / mm ² ) "Effect of invention" It has such an effect.

Since the upset pressure to the welded part of the link, whose hardness decreases in proportion to the degree of heating, is adjusted to two levels, weak and strong, the welding is performed by pushing out impure gas and impurities to the outside. Since the inner length of the link is reduced by the amount pushed out, the limit switch is activated to cut off the heating current before welding is completed, so the amount of heat given to the weld and the size of the weld crest and the link without the need for a timer It is possible to mold the inner long dimension of the uniform.

If the complete welding is performed by the upset welding method without flashing, the welding time can be shortened by adding parts to some parts without fundamentally changing the mechanical device, and deformation and welding due to shunting to the back of the link The durability of the link can be improved by preventing a large change in each chemical component of the part, and since the link is lightweight, it can be easily handled and the tire chain can be easily mounted.

Since upset welding is a resistance welding method, if the pre-pressurization is reduced, the welding resistance Joule heat in the cross-section of the link weld will increase, and the heating current can be reduced to save the current consumption. is there.

[Brief description of drawings]

1 is an overall circuit diagram, FIG. 2 is a sequence circuit diagram, FIG. 3 is a schematic diagram showing a processing operation state, FIG. 4 is a plan view showing a pressed state of a clamped link, and FIG. The same front view, FIG. 6 is an adjustment circuit diagram showing another embodiment, FIG. 7 is a plan view of the link before welding, FIG. 8 is a plan view of the link after welding, and FIG. 9 is a defective welding state. FIG. 10 is a cross-sectional view showing another defective welding state, FIG. 11 is a plan view of a divided link, and FIGS. 12 to 14 are plan views of broken links. Cylinder, 15 ... Fixed electrode, 17 ... Movable electrode, 22 ... Limit switch, 35 ... Link, 37 ... Welded part, 46 ... Foot switch, 61 ... First timer, 62 ...
… Second timer, 63 …… Third timer, 64 …… Fourth timer, 65 …… Fifth timer, X …… Strong first pressurizing current,
Y: Weak second pressurizing current.

Claims (1)

[Claims] 1. A movable structure for clamping, which is located between fixed and movable electrodes for sandwiching a welded part of a structural alloy steel link chain, by a timed operation of a first timer via a foot switch. A step of operating the electrode to continue clamping and pressurizing, and a step of timely operating the second timer by the time-up of the first timer to perform the upset first pressurization of the welding portion with a weak force by the operation of the upset pressurizing cylinder. After the time of the second timer is up, the third timer and the fourth timer are simultaneously operated to apply a strong first heating current to the welding portion for a short time by the timed operation of the third timer, and the cross section is formed by the upset first pressurization. High contact resistance and the specific resistance of the link chain material to raise the temperature of the weld by the first heating current, and a third timer After switching the first heating current to a weak second heating current and continuing to energize the welded portion, after the time-up of a fourth timer, the upset first pressurization is terminated, and the upset first Upset second pressurization stronger than pressurization is performed, the second heating current is terminated via the limit switch, and the welded part is upset second
An upset welding method for a link chain, which comprises a step of forging by pressurization and a step of ending upset second pressurization and clamp pressurization by a time-up of a fifth timer.