JP2817368B2 - Arc welding system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an arc welding system using a tungsten electrode, and more particularly to a welding system suitable for welding small parts.

<Prior Art> Arc welding using a tungsten electrode has been widely known, but conventional arc welding uses welding of relatively large parts.

Here, small parts may need to be assembled by welding.

For example, the drug injection nozzle 1 shown in FIGS. 9 (a) and 9 (b) is a small part having an outer diameter and a height of about several mm, but an orifice having a nozzle hole 3a for the following reason. It is necessary to process the plate 3 and the base 2 separately from each other with a stainless steel material and to assemble them by welding.

That is, a nozzle hole whose diameter is set to several tens μm or less
3a, in order to make the injected medicine a good injection state,
It is necessary to set the length of the hole with high accuracy.
Since the accuracy of 3a cannot be realized, it is necessary to form the orifice plate 3 from a plate material to form a predetermined nozzle hole 3a, and to assemble the nozzle hole 3a with the base 2. Some chemicals ejected from the injection nozzle are chemically very active, and react with metals such as copper, aluminum and lead to deteriorate the chemical and clog the nozzle due to the formation of crystals. Therefore, it is necessary to make the nozzle 1 stainless. However, even if the base 2 and the orifice plate 3 are formed of stainless steel, when they are soldered or brazed, the solder or the wax reacts with the chemical, and when they are bonded with an adhesive, the use durability is deteriorated. Therefore, the base 2 and the orifice plate 3 need to be welded.

As described above, the nozzle for ejecting the medicine needs to be manufactured by separately processing the base and the orifice plate with a stainless steel material, and assembling them by welding. A conventional arc welding machine is used for this welding. I couldn't do that. That is, since the conventional arc welding machine is intended for welding relatively large parts, its arc current value is large, and if this is used for welding small parts, the parts are destroyed by an excessive arc, or , Parts blow off. On the other hand, when the arc current value is reduced in the conventional arc welding machine, an arc cannot be generated.

Under the circumstances described above, there has been a strong demand for an arc welder capable of welding small parts without any problem.

The present invention has been made in view of the above-described conventional circumstances, and generates a small arc by a relatively small arc current.
Accordingly, it is an object of the present invention to provide an arc welding system capable of realizing welding of small components without hindrance.

<Means for Solving the Problems> An arc welding system according to the present invention is an arc welding system that performs welding by generating an arc between a workpiece and a workpiece using a tungsten electrode having a conical tip. When the welding between the tungsten electrode and the work is detected by the means and the tungsten electrode and the work are welded, the power supply to the tungsten electrode is put into a standby state by the maintenance means, but the tungsten electrode and the work are not welded. Sometimes, the contact detection means detects that the tungsten electrode has come into contact with the work, and the shutter mechanism provided between the worker and the welding work position is closed by the shutter drive means after the tungsten electrode comes into contact with the work, and the shutter An arc generated after the mechanism is closed is detected by the arc detection means and the electrode drive is performed. The moving electrode separates the tungsten electrode from the work.

<Operation> The arc welding system of the present invention can generate a small arc in a minute range even with a small arc current by using a tungsten electrode having a conical tip, thereby melting a minute range of a small component. To achieve good welding.

Further, the arc welding system according to the present invention is capable of wasteful power consumption and repair work for separating the electrode from the work by setting the power supply system to the tungsten electrode in a standby state when the tungsten electrode and the work are welded. Danger can be avoided.

In addition, the arc is automatically generated after a very short time after the tungsten electrode is brought into contact with the workpiece, and the welding position is a position where the tungsten electrode is brought into contact. By closing the shutter mechanism after contacting the work, welding work to a predetermined position is realized while protecting the eyes of the worker against the arc.

Further, the arc welding system of the present invention avoids welding between the work and the electrode by separating the tungsten electrode from the work after the arc is generated.

That is, the arc welding system of the present invention realizes welding of small parts without any trouble by a series of operations as described above.

The present invention is particularly effective when applied to an arc welding machine used for welding small parts, but the same applies to a conventional general arc welding machine used for welding relatively large parts. Effects can be obtained.

<Example> The present invention will be specifically described based on examples.

FIG. 1 shows an external configuration of an arc welding system for welding small parts according to an embodiment of the present invention.

The arc welding system of the present embodiment includes a controller 10, which controls the supply of current to the welding pen 11 and the workbench 12 and the supply of argon gas from the cylinder 13 to the welding pen 11. Further, a foot switch 14 for performing various manual operations and a microscope 15 having a shutter mechanism for protecting an operator's eyes against an arc are connected to the controller 10. Reference numeral 16 denotes an outlet for connecting to an AC 100V power supply.

The tungsten electrode 22 supported by the welding pen 11 has a shaft portion having a diameter of, for example, 0.5 to 1.5 mm, and as shown in FIG.
(10 to 20 degrees), a small arc can be generated by a relatively small arc current by improving the current density without impairing the strength of the electrode 22 itself.

As shown in detail in FIG. 4, the welding pen 11 has a tubular body 21 having a tapered tip and a tungsten electrode 22 supported thereon, and is supplied from the tube 23 into the tubular body 21. An argon gas is supplied to the vicinity of the tungsten electrode 22 to generate an arc. Reference numeral 27 denotes a cable that supplies an arc current to the tungsten electrode 22 and a drive current to the solenoid 24.

Here, since the molten pool formed on the workpiece by the small arc is very small, it cools and hardens in a relatively short time, so that the operator separates the electrode 22 from the workpiece W after the arc is generated. If you miss the timing,
As shown in FIG. 3, a situation in which the electrode 22 is welded to the workpiece W is likely to occur.

Therefore, the welding pen 11 is provided with a mechanism for preventing welding to the workpiece. That is, the tungsten electrode 22 is attached to the mover 25 of the solenoid 24,
The tungsten electrode 22 is held in a state where it is projected by a predetermined amount from the distal end of the tubular body 21 by being urged to the distal end side by a spring 26. Detecting by means, the solenoid 24 is actuated, and the tungsten electrode 22 is slightly retracted against the spring 26 to prevent welding between the work and the tungsten electrode 22.

Further, the microscope 15 is provided as described above in order to perform a fine welding operation on small parts, and an operator visually recognizes a welding location with the microscope 15 and performs an operation.

The microscope 15 has a lens 50 as shown in detail in FIG.
A support base that can move the housing 51 holding the
A shutter plate 53 that is supported by 52 and that can block the optical path of the lens 50 is provided in the housing 51. The shutter plate 53 is rotatably (up and down in FIG. 4) mounted inside the housing 51 via a support shaft 54, and is normally provided by a spring 55 wound around the support shaft 54. 53
Is jumped up to an upper position retracted from the optical path of the lens 50. A solenoid 43 is attached to the housing 51, and the movable element 56 of the solenoid 43 is normally positioned at a position where the movable element 56 is retracted into the solenoid by a spring 57. That is, according to the microscope 15, the welding position of the work can be enlarged and visually recognized through the lens 50 in a normal state, and when the solenoid 43 is activated by contact with the tungsten electrode 22 as described later, the movable element 56 The shutter plate 53 is pushed downward to block the optical path of the lens 50, and blocks arc light incident through the lens 50.

FIG. 6 shows a circuit configuration of the above-described arc welding system.

In the figure, reference numeral 30 denotes a central processing unit (CPU), and a controller 10 plays a central role in automatic welding control.

Reference numeral 31 denotes a capacitor. The capacitor 31 is charged by a charging power supply 33 connected to an AC 100 V power supply via a charging switch 32 controlled by the CPU 30. One electrode of the capacitor 31 is a thyristor switch 34 controlled by the CPU 30,
The other electrode of the capacitor 31 is connected to the workbench 12 via the current limiting resistor 35 and the tungsten electrode 22. A discharge switch 36 is provided between the electrodes of the capacitor 31.
Controlled by U30.

A resistor 37 is provided to allow a very small current to flow by bypassing the thyristor switch 34. The very small current is guided to a voltage level detection circuit 38, and various states are detected and input to the CPU 30. For example, when the tungsten electrode 22 is brought into contact with a work placed on the work table 12, the voltage drops momentarily, so that the state can be detected, and the tungsten electrode 22 is welded to the work placed on the work table 12. When this occurs, the voltage does not rise, so that the state can be detected.

Further, the charging circuit is provided with a transformer 39 for detecting an arc current. The detection of the arc current by the detection circuit 40 detects the occurrence of an arc, and inputs the detection signal to the CPU 30.

A solenoid driver 41 controlled by the CPU 30 is provided. The driver 24 drives the tungsten electrode 22 by the solenoid 24 and the cylinder 13 to the welding pen 11.
Solenoid valve 42 provided in the argon gas supply path to the valve, a solenoid that drives the shutter mechanism of the microscope 15
Drive 43.

Note that a control signal from the foot switch 14 is also input to the CPU 30, and various manual operations such as resetting of a control system are performed based on the input.

The operation of the arc welding machine having the above configuration will be described with reference to the flowchart shown in FIG.

First, when the main power supply of the welding machine is turned on and the circuit is started, all switches, actuators, and valves provided in the welding machine are turned off to an initial state (step
S1).

Next, after turning on the switch 36 to once discharge the capacitor 31 (step S2), the switch 36 is turned off and the charging switch 32 is turned on to charge the capacitor 31 (step S3).

Next, it is confirmed that the tungsten electrode 22 is not welded to the work based on the signal from the voltage level detection circuit 38 (Step S4). As a result, when welding of the electrode 22 has occurred, the switch 32 is turned off to turn off the charging power, and the switch 36 is turned on to discharge the capacitor 31 once (step S5). The power supply system to the electrode 22 is set in a standby state until resetting is performed by 14 (step S6). Accordingly, while the worker is performing the work of separating the welded electrode 22 from the work, the charging power of a relatively high voltage is not supplied, so that unnecessary power consumption can be prevented and the work can be prevented. Can be performed safely.

On the other hand, when there is no welding of the electrode 22, the operator operates to judge whether the tip of the tungsten electrode 22 has contacted the workpiece based on a signal from the voltage level detection circuit 38, and the operator turns the electrode 22 to the workpiece. It is in a standby state until it is hit on the portion to be welded (step S7).

Next, when the tip of the tungsten electrode 22 comes into contact with the workpiece, the solenoid valve solenoid 42 is turned on and the welding pen is turned on.
The argon gas is supplied to 11 and the solenoid 43 is turned on to close the field of view of the microscope 15 with the shutter mechanism (step S8). Then, in order to ensure that the shutter is closed in consideration of the operation delay of the solenoid 43, a slight delay time (0.2 seconds in this embodiment) is provided (step S).
9), the thyristor switch 34 is turned on to generate an arc (step S10).

As described above, the visual field of the microscope 15 is closed based on the contact of the tungsten electrode 22, and the eyes of the operator can be protected from the subsequently generated arc. Even if the field of view is blocked in this way, there is no operational problem since the welding position is defined at the contact position of the electrode 22.

Next, it is determined whether an arc has occurred within a predetermined time (2 seconds in this embodiment) based on the detection value of the arc current detection circuit 40 (step S11). The solenoid 42 is turned off to stop supplying argon gas, the solenoid 43 is turned off, the shutter mechanism of the microscope 15 is opened, and the thyristor switch is turned off.
Turn off 34 to stop the supply of arc current (step S1
2) Turn on the switch 36 to discharge the capacitor 31 (step S13), and execute again from the above step S3.

On the other hand, when an arc occurs within a predetermined time, the solenoid 24 is turned on to pull in the tungsten electrode 22, the solenoid 43 is turned off, the shutter mechanism of the microscope 15 is opened, and the thyristor switch 34 is turned off to reduce the arc current. The supply is stopped (step S14). That is,
Using the detection value of the arc current detection circuit 40 as a start timing, the solenoid 24 is quickly turned on after the arc is generated to separate the tungsten electrode 22 from the work so that the tungsten electrode is not welded to the weld formed by the arc. ing.

Then, with a delay (0.4 seconds in this embodiment) required for the operator to pull the welding pen 11 to separate the workpiece from the workpiece (step S15), the solenoid 24 is turned off, and the tungsten electrode 22 is returned to the original position by the spring 26. And the solenoid valve solenoid 42 is turned off to stop supplying argon gas (step S16), and the switch 36 is turned on to discharge the capacitor 31 (step S17).
The process is repeated from step S3.

The operation of assembling the nozzle for chemical injection by the arc welding system having the above configuration will be described with reference to FIGS. 8 (a) to 8 (c).

As shown in FIG. 8 (a), the base 2 and the orifice plate 3 having the nozzle holes 3a are prepared separately from stainless steel.

Then, the base 2 is supported on a rotatable jig, and the orifice plate 3 is placed on the base 2, and the orifice plate 3 is pressed and fixed by the pressing member 6.

Then, as shown in FIG. 8 (b), an arc is blown by the tungsten electrode 22 at the joint between the base 2 and the orifice plate 3, and the base 2 and the orifice plate 3
To form a welded portion 8 extending between the two. Such a work is sequentially performed at predetermined time intervals while rotating the work with the jig, so that the adjacent welded portions 8 overlap each other by about 50%, and a gap between the base 2 and the orifice plate 3 is formed. Do not weld.

Then, the nozzle 1 as shown in FIG. 8 (c) is finished.

In the above welding work, since the tip of the tungsten electrode 23 is pointed, the arc concentrates in a very small area of the work, and a molten pool is formed in a very small area of the work before heat is diffused. Can be made. Further, the adjacent welded portion 8 is formed after the heat of the previously formed welded portion is lowered to some extent, so that the welded portion 8 is not excessively heated. From these facts, it is possible to avoid excessive heating of the work in the above-described welding operation, and to prevent damage and deterioration of the quality of the work, which is a small component.

In the above embodiment, an example was shown in which a nozzle for chemical injection made of stainless steel was used. However, the arc welding machine according to the present invention uses other small parts (for example, pressure sensors, etc.) made of other materials. It can also be used for production, and there are no special restrictions on its use.

Further, in the present embodiment, the driving means for separating the tungsten electrode 22 from the work after the arc is generated by the solenoid 24 is configured, but other known means may be used. Also,
As the arc detecting means, other known means such as a means for directly detecting the occurrence of an arc optically, other than a means for detecting the occurrence of an arc from an arc current, may be used.

Further, in this embodiment, the driving means for closing the shutter plate 53 after the contact of the tungsten electrode with the solenoid 43 is formed, but other known means may be used. Also, the tungsten electrode contact detection means may use other known means, such as one that directly detects the tungsten electrode optically, other than one that detects from the arc current.

In the present embodiment, the charged capacitor 31 and the electrode 22
By supplying power to the power supply, the occurrence of arcs is suppressed in a short time to prevent damage to the work, which is a small part, but electronic switches such as thyristors and transistors are provided between the constant voltage source and the electrode 22. Alternatively, this switch may be controlled by the CPU to be turned on for a short time to control the arc generation time.

<Effects of the Invention> According to the present invention, the tungsten electrode used in the arc welding machine has a conical tip, so that a small arc can be generated in a minute range even with a small arc current, and the small parts Range can be melted. Therefore, small parts such as nozzles for drug injection can be assembled by welding without any trouble, and small parts with high performance and high reliability can be manufactured.

Further, according to the present invention, when the tungsten electrode and the work are welded, the power supply system to the tungsten electrode is set in a standby state, so that wasteful power consumption is prevented and the electrode is separated from the work. Safety can be ensured.

Further, according to the present invention, since the shutter mechanism provided between the worker and the welding work position is closed after the tungsten electrode comes into contact with the work, the worker is not disturbed by the welding work with respect to the arc. Can protect eyes. In particular, the present invention is very effective when applied to an arc welding machine that realizes welding of small parts by making the arc extremely small, and assures the operator's eyes against such an arc having a great influence on the eyes. Can be protected.

Further, according to the present invention, the tungsten electrode of the arc welding machine is automatically separated from the work after the arc is generated, so that welding between the work and the electrode is reliably avoided to realize a smooth and efficient welding operation. can do. In particular, the present invention is very effective when applied to an arc welding machine that realizes welding of small parts by making a weld pool formed by an arc a very small one, and performs an operation of separating a welding pen from a workpiece after an arc is generated. Since the welding can be performed without relying on the above-mentioned skills, welding of the electrodes can be avoided and the work efficiency can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an entire configuration of an arc welding system according to one embodiment of the present invention, FIG. 2 is a perspective view showing a tip portion of a tungsten electrode, and FIG. 3 explains welding between a tungsten electrode and a work. FIG. 4 is a sectional view showing a configuration of a welding pen of the arc welding system according to one embodiment of the present invention, and FIG. 5 is a sectional view showing a microscope of the arc welding system according to one embodiment of the present invention. FIG. 6 is a block diagram showing a circuit configuration of an arc welding system according to one embodiment of the present invention;
FIG. 7 is a flowchart for explaining the operation of the arc welding system according to one embodiment of the present invention, and FIGS. 8 (a) to (c).
FIG. 9A is a conceptual view for sequentially explaining the assembling work of a nozzle for drug injection, FIG. 9A is a perspective view of the nozzle for drug injection, FIG.
FIG. 2B is a cross-sectional view of a drug injection nozzle. 11 is a welding pen, 12 is a workbench, 14 is a foot switch, 22 is a tungsten electrode, 24 is a solenoid, 30 is a CPU, 31 is a capacitor, 32 and 36 are switches, 33 is a charging power supply, 37 is a resistor, and 38 is A voltage level detection circuit, 40 is an arc current detection circuit, 41 is a solenoid driver, 43 is a solenoid, 53 is a shutter plate, and W is a work.

Continuation of front page (56) References JP-A-58-3787 (JP, A) JP-A-57-1575 (JP, A) JP-A-61-3669 (JP, A) (58) Fields investigated (Int) .Cl. ⁶ , DB name) B23K 9/06, 9/10, 9/095 B23K 9/32, 37/00, 9/00

Claims (1)

(57) [Claims] An arc welding system in which welding is performed by generating an arc between a workpiece and a workpiece using a tungsten electrode having a conical tip, wherein welding between the tungsten electrode and the workpiece is detected by welding detection means. When the tungsten electrode and the work are welded, the power supply to the tungsten electrode is put into a standby state by the maintenance means, while when the tungsten electrode and the work are not welded, the tungsten electrode contacts the work by the contact detection means. And the shutter mechanism provided between the worker and the welding operation position is closed by the shutter driving means after the tungsten electrode comes into contact with the work, and the arc generated after the shutter mechanism is closed is detected by the arc detecting means. The tungsten electrode is separated from the work by the electrode drive means Arc welding system according to claim and.