JPS58196183A - Butt resistance welding machine for fine wire - Google Patents

Abstract

PURPOSE:To provide a butt resistance welding machine for fine wires for the purpose of satisfactory welding of the fine wires of a TiNi alloy, by constituting so that the application timing of welding current and the working force on a molten part can be controlled variously with the respective detection signals of a load cell and a displacement sensor. CONSTITUTION:A motor 16 is operated to apply minute pressure between moving electrodes 12, 13; at the same time, the pressurizing force thereof is detected with a load cell 18. The movement of the electrodes 12 and 13 is stopped to maintain the pressurizing force constant at the point of the time when the pressurizing force increases slightly. Welding current is applied in this state for a short time between TiNi alloy wires 14 and 14 to melt the contact part thereof, thereby decreasing the pressurizing force. The decrease in the pressurizing force is detected 18, and the motor 16 is run at a high speed with the detection signal thereof to thrust the electrode 12 quickly to extrude the molten part to the outside, thereby completing the welding. The welding current is applied during this time in the state of the small pressurizing force on the alloy wires 14, that is, in the state of the large electric resistance in the contact part; therefore, the heated part is confined within the small local part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a butt resistance welding machine for thin wires suitable for welding TiNi-based shape memory alloy thin wires.

In recent years, shape memory alloys have attracted attention as elements that convert thermal energy into mechanical energy. A typical shape memory alloy is TiNi alloy, but TiNi
Butt welding of thin alloy wires is very difficult and has many problems. For example, (1) when melting the tip of a TiNi alloy wire for welding, the surface tension of the molten TiNi alloy is large, so it is difficult to join, and (2) when the molten wire is resolidified by cooling, that part (3) Deterioration of shape memory occurs in the heat-affected zone near the weld, so heating points must be kept to a minimum. , etc.

Conventionally, it has been said that electron beam welding is suitable for welding TiNi alloy wires. If this electric r-beam welding is used, it is possible to perform high-energy □-one time welding, so it is possible to perform one-time welding with high energy. The heat-affected zone can be narrowed. (- or (-) On the other hand, there is a drawback that sufficient welding strength cannot be obtained because the above-mentioned re-solidified structure becomes eroded.

Another drawback is that electron beam welding equipment is very expensive.

On the other hand, a simple welding machine and 1
．． There is a butt resistance welding machine shown in FIG. 1 in the same figure
2 is a fixed electrode, and 2 is a moving electrode, each of which chucks a thin metal wire 3. 4 is a pressurizing spring, 5 is a moving unit, 6
is a rail. The moving electrode 2 and the moving unit 5 are installed so as to be slidable on the rails 6. 7 is a capacitor, and 8 is a switch for discharging the capacitor 7.

When joining thin metal wires, the moving unit 5 is moved to the right by a driving mechanism such as air pressure or a motor (not shown). At this time, the pressurizing spring 4 moves '1 ((pole 2
is pressed to bring the tips of the thin metal wires 3 into contact and to increase the contact IF force at the contact point at 9i.

When the moving north pole 2 reaches a suitable position, the switch 1 and switch 8 are turned on and the capacitor 7 is discharged. At this time, the contact portion of the thin metal wire 3 is melted by instantaneous heat generation due to the contact resistance. Welding is completed when this molten part cools down. Figure 2 shows the changes in pressure a and welding current S.
It is.

Using a resistance welding machine that performs welding as described above, TiNi
When welding alloy wires, it is ideal to weld so that the base metals are directly joined.

In reality, it is impossible to directly join base materials together, but it is necessary to make the area occupied by the fusion zone and the heat affected zone as narrow as possible in order to improve strength or maintain shape memory. In order to achieve this point, when joining the alloy wires, after melting the contact part, strong pressure I2 is applied to push out the melted part 9 and the heat affected zone 11 to the outside as shown in FIG. and a method of removing the heat-affected zone IN. 1
0 is the part of the base material.

However, it is difficult to perform excellent joining using the T method using the conventional welding machine shown in Figure 1.1. The j31 reason is as follows. If strong pressure is applied to the contact area when welding current is applied, the contact resistance will be low. However, in the conventional resistance welding machine shown in FIG. If a weak pressure is applied to the contact part when applying current, it will not be possible to apply a strong Vrc pressure rapidly after contact, and as a result, the melted part will not be pushed out sufficiently, resulting in a fragile re-circulation. This results in many solidified parts remaining.

As described above, the present invention achieves a Ti
An object of the present invention is to provide a welding machine for performing good welding of Ni alloy wire.

Hereinafter, one embodiment of the butt resistance welding machine for thin wires according to the present invention will be described in detail #II using the drawings.

FIG. 4 is an explanatory diagram of an embodiment of a butt resistance welding machine for thin wires according to the present invention. Reference numerals 12 and 13 denote movable electrodes, and TiNi alloy wires 14 are respectively chucked with their tips abutting each other. The moving electrode 12 is a 15-piece rail.
．． 13 is installed so as to be slidable left and right on the rail 15. Reference numeral 16 is a motor capable of forward rotation, reverse rotation, and stop, and a drive shaft 17 having a male thread groove is fixed thereto. On the other hand, the movable electrode 12 is provided with a female thread groove, and the drive shaft 17 is
3, 18 that meshes with the male thread groove of ! d a load cell that detects the pressure of the moving electrode; 19 is a displacement sensor that detects the amount of movement of the moving electrode; 20 control circuits;
A circuit for applying a welding current to the Ni alloy wire, a circuit for receiving signals from a load cell and a displacement sensor, and controlling the driving of the motor are built-in.

Next, the welding current generating circuit in the control circuit 20 will be explained. FIG. 5 is a circuit diagram of a welding current generating circuit. 2
1 is a power source, and 22.23 is a welding current output terminal, which is connected to a moving electrode 12.13, respectively. C,, G2...,
CN is a ++J variable capacitor, and each thyristor S
,,S2. ..., SN are connected in series. R,,R2
, . . . , RN are variable resistors, and these are connected to the source 21. , nf variable resistance R1R2+ ..., R
If you adjust N, the capacitor (-1+c,.

...Charge '+[pressure for +CN can be adjusted. Before welding, the capacitors C, C2, . . . , CN are charged. When the application of welding current starts (for example, when the load cell detects that the welding force has reached a small constant value and stops the motor to maintain the constant welding force), a pulse signal is sent to gate 1-G of thyristor S1. is applied. Then, at a predetermined timing, gate G2. G3
．． . . , GNK are sequentially applied, and their combined waveform is applied from the output terminal 22.23 to the moving electrode 12.18 in a form similar to the waveform of the welding current shown in FIG.

According to the following resistance welding machine, the 1st floor as shown in FIG.
- Welding can be performed by applying a force a and a welding current s to the contact part. That is, the moving electrode 1 is moved by operating the motor 16 without switching.
2. At the same time, a minute pressure is applied between 7 and 13 (the applied force is detected by the load cell 18).

When J made by J fj is slightly removed, move electrodes 12 and 1.
Stop the movement of step 3 and keep the pressure constant. In this state, a short-time welding current is applied to the TiNi alloy wire. Then, the 4th contact part melts, and this melting reduces the pressing force.

The load cell 18 detects this low pressure 1. In response to this detection signal, the motor 16 is rotated rapidly and the movable electrode 12 is pushed into the wheels a' and 1.1, pushing out the molten part of the contact area.Thus, welding is completed. According to the seven welding sequences, the welding current is applied in a state where the t-C force applied to the alloy wire is small, that is, the electrical resistance of the contact part is large, so the heated part can be contained within a small area. Since the pressure of the heat-affected zone is rapidly increased to a large extent, almost all of the melted zone and heat-affected zone can be extruded.

In addition to the above-mentioned welding operation, it is also possible to apply a weak welding electric current (7) again after welding is completed, as shown in Figure 7, and reheat (anneal). Also, the following welding operation is also possible. . That is, first, the motor 16 is operated to apply a slight pressure between the movable electrodes 12 and 13 so that the welding surfaces touch each other, a welding current is applied 12, and almost simultaneously with the application of the current, the welding surfaces are separated by a slight V. Adjustment of this IF pole position is carried out using the positions a and -j from the displacement sensor 19. If the current continues to flow for a certain period of time during the movement of this electrode, an arc occurs [7] The heat generated during the arc causes the end face of the alloy wire to The alloy wire is melted.Then, pressure is applied rapidly to push out the molten part to complete welding.According to this welding operation, the end face of the alloy wire is melted by the arc, so there is no need to flatten the end face before joining.

In the welding machine described above, the timing of application of welding current and the pressure applied to the contact part can be adjusted with type 4 using the detection signal of the load cell 18 and the detection signal of the displacement sensor 19. By using the welding current generation circuit shown in the figure, it is possible to weld by adjusting the welding current waveform in various ways.
It can also successfully join many alloys other than alloy wires.

1- According to the present invention explained in detail, it is possible to adjust the pressurizing force or welding current to the optimum value especially when joining Ti-Ni alloy wires where strict welding conditions are required, so that strength and shape memory properties can be improved. Ti Ni with +Q in both cases
It is possible to join alloy wires,

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional welding machine, Fig. 2 is a graph diagram of pressurizing force and welding current of the conventional welding machine, Fig. 3 is a side view of a metal wire welding part, and Fig. 4 is a diagram according to the present invention. An explanatory diagram of an embodiment of a butt resistance welding machine for thin wires, a circuit diagram of a welding current generating circuit for the 51st welding machine, and FIGS. 6 and 7 show graphs of the pressurizing force and welding process. In the figure, 12.13: Scratch 4I] electrode +4: T1Ni
Alloy wire 15: Rail 16: Motor 17:
Drive shaft 18: Load cell 19: Displacement sensor
20: Control circuit agent Patent attorney Aihiko F. (and 2 others) Figure 1 ↑ No. 211 (

Claims (1)

[Claims] 1. Holding the metal wires to be welded on an electrode, abutting the end faces of the metal wires, and applying a welding current to the contact portion caused by the butt.1. A butt resistance welding machine for thin wires that performs welding by means of a metal wire includes means for directly driving the electrode with a motor or the like to apply pressure to the contact portion, and pressure detection means for detecting a pressurized state of the contact portion of the metal wire. A butt resistance welding machine for fine wire, characterized in that the welding current or the amount of pressure applied to the contact portion of the metal wire is controlled based on the detection signal of the pressure detection means. 2. In a butt resistance welding machine for fine wires, which holds a metal wire to be welded on an electrode, butts the end faces of the metal wire, and performs welding by applying a welding current to the contact portion resulting from the butt, the contact portion is applied. A means for directly driving the electrode with a motor or the like to press the electrode, and a position detecting means for detecting the position of the electrode, and a welding current or a contact portion of the metal wire is controlled based on a detection signal from the position detecting means. A butt resistance welding machine for fine wire that is characterized by controlling the amount of pressure applied. & Comprising a circuit means in which a plurality of circuit elements each having a variable capacitance capacitor and a thyristor connected in series are connected in parallel, a means for adjusting a charging voltage to the capacitor, and a means for controlling a gate of the thyristor. 2. The butt resistance welding machine for thin wires according to claim 1, wherein the discharge current of the capacitor is a welding current. ↓ Comprising circuit means in which a plurality of circuit elements in which a variable capacitance capacitor and a thyristor are connected in series are connected in parallel, a means for adjusting the charging voltage to the capacitor, and a means for controlling the gate of the thyristor. 3. The butt resistance welding machine for thin wires according to claim 2, wherein the discharge current of the capacitor is a welding current.