JP3441856B2 - Arc start method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc starting method and an arc starting apparatus for TIG arc welding, and particularly to an arc starting method and an arc starting method for generating an arc by touching the electrode tip of a welding torch with a welding base metal. Regarding the device.

[0002]

2. Description of the Related Art T using non-consumable tungsten as an electrode
In IG (tungsten inert gas) arc welding,
Generally, a method in which a high frequency voltage of several thousand volts is superimposed and applied between the electrode tip of the welding torch and the welding base material to generate an arc is widely used. For example, "T
IG welding equipment and its use, pp. 43-47 "describes a high frequency generator (Issue: Industry Bulletin 1973).
October 5th). However, it has been pointed out that the high frequency voltage causes noise and radio wave interference. As a measure for reducing the noise generation and the radio wave interference, for example, Japanese Patent Laid-Open No. 56-4376 discloses a DC TIG welding machine which discloses a device for superimposing a high voltage pulse instead of the high frequency voltage.

Further, in an apparatus used in a place where various precision instruments which are easily affected by electric noise are located in the vicinity, the tip of the electrode of the welding torch is welded without using high frequency voltage or high voltage pulse of several thousand volts. A touch start method in which a base material is touched for a short time to generate an arc may be used. In this touch start method, a voltage of several tens of volts is applied between the electrode and the welding base metal, and at the same time as the tip of the electrode contacts the welding base metal, the lowering operation of the welding torch is temporarily stopped to contact the electrode. While energizing the welding base metal, the welding torch is raised to a steady position to generate an arc from the electrode tip.

[0004]

The arc generating method in which a high voltage pulse is superposed and applied instead of a high frequency voltage is effective as a measure for reducing noise generation and radio wave interference, but it has reached a sufficient solution range. Absent. On the other hand, by using the arc generation method of the touch start method, the problems of noise generation and radio interference can be solved. However, as a problem peculiar to this arc generation method, a start error occurs because the arc cannot be ignited due to a defect in the energization of the electrode and the rising timing of the welding torch. Deviates or its electrode welds to the welding base metal,
The damage and wear of the electrode tip is remarkable, and so on.

The present invention has been made in view of the above problems, and an object thereof is to improve the arc start method to prevent start mistakes, electrode welding, and reduce electrode wear.

[0006]

In order to achieve the above object, the present invention lowers a welding torch having a non-consumable electrode at its tip in an atmosphere of an inert gas shield and lowers the welding torch. In an arc start method in which an arc is generated between the electrode tip of the welding torch and the welding base metal by contacting the material and raising it after energization, the welding torch is lowered and contact detection is performed between the electrode and the welding base material. The welding sub-power supply voltage is applied to detect that the electrode tip of the welding torch has come into contact with the welding base metal, and at the same time the welding torch lowering operation is stopped, after which the welding main power supply voltage is applied. At the same time as or immediately after the start of the application of the initial current, the electrode tip of the welding torch that was in contact with the welding base metal is moved so as to be separated in an oblique direction to perform arc ignition.

In this case, the contact detection current is set to 1 A or less,
The range of the initial current that flows between the electrode and the welding base metal is 5 to 5
At 0A, the separation angle of the electrode tip with respect to the welding base material and the height range are set to 20 to 60 degrees and 0.5 to 1.5 mm, respectively.

Further, when the initial current supplied from the main power supply is cut off in the middle, the arc start operation is temporarily stopped, and then the position different from the position where the electrode tip is in contact is in the front-rear direction or the left-right direction. The welding torch is moved to, and the arc start operation is restarted from the position after the movement.

Further, the above object is to lower the welding torch and to apply a voltage of a sub power supply for contact detection between the electrode and the welding base metal so that the electrode tip of the welding torch contacts the welding base metal. The welding torch lowering operation is stopped at the same time that the welding torch is detected, and then the welding main material is in contact with the welding base metal at the same time as or immediately after the start of the initial current application by applying the voltage of the main power supply for welding. Perform arc firing by moving the electrode tip of the torch diagonally away from the arc.Furthermore, the electrode tip position of the welding torch after arc firing is the time to reach the initial welding current or the steady welding current. It is also achieved by raising and moving inward to a stationary position.

Further, the above-mentioned object is to lower the welding torch provided with a non-consumable electrode at the tip thereof in the atmosphere of the inert gas shield so as to bring the welding torch into contact with the welding base metal and to raise it after energizing the welding torch. In an arc start device that generates an arc between the electrode tip of and the welding base material, a traveling carriage that moves in the welding direction by engaging a vertical drive shaft that vertically moves the welding torch and a horizontal drive shaft that horizontally moves the welding torch, The welding torch is provided with a welding power source for energizing for welding between the electrode in the welding torch and the welding base material, and a contact detection power source for detecting electrode contact,
After contacting the electrode with the welding base metal and energizing, the electrode tip of the welding torch is pulled up diagonally to perform arc ignition, and the electrode tip position of the welding torch after arc ignition is set to the initial welding current time or the steady welding current. This is achieved by providing the welding control device that controls the vertical drive shaft, the horizontal drive shaft, and the contact detection power supply so as to move up and move to the steady position within the time required for reaching.

[0011]

As described above, by applying the voltage of the sub power supply for contact detection between the electrode and the welding base metal, it is possible to detect that the tip of the electrode is in contact with the welding base metal by decreasing the applied voltage or generating the contact current. Can be detected from. This contact current of 1 A or less is sufficient. Moreover, the tip of the electrode can be prevented from being damaged by stopping the descending of the welding torch immediately upon detection of this contact. Then, by applying the voltage of the main power source for welding and starting the energization of the initial current, at the same time, the electrode tip of the welding torch that was in contact with the welding base metal was moved diagonally away from each other without causing electrode welding. ,
The electrode can be detached from the welding base metal with a small reaction force, which facilitates arc ignition. That is, the touch start method is performed as if the matchstick was rubbed to ignite.

In this case, if the initial current for energization is too small, it may cause arcing mistakes, and if it is too large, it may cause electrode adsorption and electrode wear. Therefore, the appropriate initial current range is about 5 A or more. Also, it is desirable to set it to 50 A or less. In addition, if the separation angle of the electrode with respect to the weld metal surface is too large, the separation effect of the electrode will be small, and if the separation angle is too small, the arc point will easily move in the lateral direction. It is desirable to set it within 20 to 60 degrees. With respect to the height direction, the electrode of the welding torch is not pulled up to a steady height position (for example, about 2 to 3 mm) at a stroke, but the electrode is stopped at about 1.5 mm or less to prevent arc breakage. Height is 0.
By setting the thickness to 5 mm or more, it is possible to eliminate the risk of the electrode tip re-contacting with the welding base material that is melted by the arc heat after arc ignition and melting and consumption. Further, in the unlikely event that the initial current is cut off on the way, the arc starting operation is temporarily stopped, the welding torch is moved to another position, and then the arc starting operation is restarted, whereby the arc ignition becomes easy.

Further, by raising and moving the electrode tip position after the arc is ignited to the steady position within the time period of the initial current or the time period until the steady welding current is reached, arc breakage or positional deviation is caused. It is possible to form a stable molten arc and a good molten pool in the welding base metal from the tip of the electrode, without causing the above phenomenon.

[0014]

EXAMPLES The contents of the present invention will be specifically described below with reference to examples. FIG. 1 shows a welding apparatus according to an embodiment for carrying out the arc start method of the present invention. A welding torch 4 provided with a non-consumable electrode 1 through which a shield gas 2 flows, its welding torch 4, and a torch holder. 6, a vertical drive shaft 7 for vertically moving the welding torch 4, a horizontal drive shaft 11 for horizontally moving the welding torch 4, a traveling carriage 12 engaged with both shafts and moving in the welding direction, and an electrode 1 in the welding torch 4.
Welding power source 8 for energizing for welding between the base metal and the welding base material 5, another contact detection power source 9 for detecting electrode contact, and welding for collectively controlling and controlling each axis and each power source. It is composed of a control device 10.

Next, the arc start method will be described with reference to FIGS. 2 and 3. FIG. 2 is an explanatory view showing the state of the arc start operation, in which the positional relationship between the welding base material 5 and the welding torch 4 is shown below, and the moving direction of the welding torch is shown above as a vector. In (1), a voltage is applied from the contact detection power source 9 between the electrode 1 and the welding base material 5, and at the same time, the welding torch 4 starts to descend, and the electrode 1 moves downward toward the welding base material 5 by a downward movement 7a. (2) is the state of the electrode 1 by contact detection (for example, voltage detection or current detection)
It shows a state in which the tip of the welding torch 4 is stopped at the same time when the tip comes into contact with the welding base material 5. A contact current of 1 A or less flows from the contact detection power supply 9 during contact of the electrode 1. In (3), from the situation shown in (2), the welding power source 8 starts to supply the initial current, and at the same time, the vertical drive shaft 7 and the horizontal drive shaft 11
By moving (elevating operation 7c and right moving operation 11a), the tip of the electrode 1 of the welding torch 1 is pulled obliquely to the right and the arc 15 is moved.
a The state of being ignited is shown. The contact detection power supply 9 is stopped during this operation. In (4), from the situation shown in (2), the vertical drive shaft 7 and the horizontal drive shaft 11 are moved so that the welding torch 4 moves to the steady position (ascending operation 7d and left moving operation 1
1b) The tip of the electrode 1 is pulled up in the left diagonal direction. Further, (5) is an arc 15 between the electrode 1 and the welding base metal 5.
The state in which the traveling carriage is made to travel after the initial current flowing in b is increased to the steady welding current is shown.

FIG. 3 shows an arc execution operation execution procedure. Each operation shown in FIG. 2 corresponds to the operation classification from (1) to (5). Here, the contact detection power supply 9
A shield gas 2 is supplied to protect the tip of the welding torch 1 from the atmosphere before applying a voltage from the. Further, before stopping the contact detection power supply 9 for flowing the contact detection current 9b, the welding power supply 8 is activated to start the energization of the initial current. Switching the energization to the electrodes becomes smooth by allowing a slight overlap time. A suitable initial current range is preferably from about 5A to at most 50A. The reason for this is that if the initial current for energization is too small, it will cause arcing mistakes, and if it is too large, it will cause electrode adsorption and electrode consumption. In the operation of (3), as shown in FIG. 2 (3), the tip of the electrode 1 of the welding torch 4 is pulled up obliquely with respect to the welding base metal so that electrode welding does not occur and welding is performed with a small reaction force. The electrode can be detached from the base material, and arc ignition becomes easy. It's like rubbing a matchstick to ignite. The operation of pulling up the tip of the electrode 1 in an oblique direction can be performed by the ascending operation 7c of the vertical drive shaft 7 and the right moving operation 11a of the left and right drive shaft 11, and furthermore, by appropriately setting the moving speed and moving distance of the both, an appropriate position can be obtained. Can be taken to. The proper range of the separation angle of the electrode tip with a good arc firing and its height is about 20 to 60 degrees and about 0.5 to 1.5 mm. The reason is that if the electrode separation angle is too large, the electrode separation effect becomes small, and conversely, if the electrode separation angle is too small, the arc point tends to move laterally. Further, with respect to the height direction, if the electrode is pulled up to a steady height position (for example, about 2 to 3 mm) at once, arc breakage is likely to occur. On the contrary, if it is too small, it is melted by arc heat after arc ignition. This is because the electrode tip may come into contact with the welding base metal again and melt and wear. Furthermore, if the initial current is cut off in the middle of operation (3), the arc start operation is temporarily stopped, and then the welding torch is moved to a different position in the front-back direction or left-right direction of the welding line different from the contact position of the electrode. The movement is performed, and the operations (1) to (3) are performed again from the position after the movement. The arc ignition is facilitated by moving the contact position of the electrode and restarting the arc start operation.

The operation of (4) for raising and moving the electrode after the arc is ignited to the steady position is the time (t) of the initial current.
s) or the time until reaching a steady welding current (t
Go within w). By this operation, it is possible to always form a stable arc and a good molten pool in the welding base metal from the tip of the electrode without causing arc breakage or displacement. In this embodiment, the vertical drive shaft 7 and the horizontal drive shaft 11 are moved to pull up the electrode tip of the welding torch 4 in an oblique direction. However, instead of the horizontal drive shaft 11, a traveling carriage in the welding direction is used. It goes without saying that the same operation can be performed by moving it.

[0018]

As described above, the arc starting method according to the present invention enables good arc ignition, prevents start mistakes and electrode welding, and reduces electrode wear, resulting in arc breakage and displacement. Without doing so, it is possible to always form a stable arc and a good molten pool in the welding base metal from the electrode tip.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment showing a welding apparatus for performing an arc start method of the present invention.

FIG. 2 is an explanatory diagram showing an arc start operation situation of the present invention.

FIG. 3 is an explanatory diagram showing an arc execution operation execution procedure of the present invention.

[Explanation of symbols]

1 ... Electrode, 2 ... Shield gas, 3 ... Gas passage, 4 ... Welding torch, 5 ... Welding base metal, 6 ... Torch holder, 7 ... Vertical drive shaft, 7a, 7b, 7c, 7d ... Vertical movement operation, 8 ... Welding Power supply, 8a ... Operation of welding power supply, 9 ... Contact detection power supply, 9
a ... Operation of contact detection power source, 10 ... Welding control device, 11 ...
Left and right drive shafts, 11a, 11b, 11c, 11b ... Left and right movement operation, 12 ... Traveling carriage, 12a ... Traveling operation, 13 ... Shaft holder, Is ... Initial current, Iw ... Steady welding current, ts ...
Initial current time, tw: steady welding current arrival time.

Front Page Continuation (72) Inventor Nobuo Shibata 502 Jinrachicho, Tsuchiura City, Ibaraki Prefecture, Hitachi Ltd., Mechanical Research Laboratory (72) Inventor Yoshio Nakajima, 502, Jinmachicho, Tsuchiura City, Ibaraki Hitachi Ltd., Mechanical Laboratory (72) ) Inventor Hironari Kikuchi 502 Kintate-cho, Tsuchiura-shi, Ibaraki, Hitachi Ltd., Mechanical Research Laboratory (72) Inventor Masahiro Kobayashi 3-1-1, Sachi-cho, Hitachi, Ibaraki Hitachi Ltd. (72) Invention Takeo Uehara 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi, Ltd. Hitachi factory (72) Inventor Hideyuki Akiyoshi 4-153, Obara, Yao-shi, Osaka Matsumoto Machinery Co., Ltd. (56) References JP-A-5-285648 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23K 9/067 B23K 9/00 330 B23K 9/12 331

Claims (5)

(57) [Claims] 1. A welding torch having a non-consumable electrode provided at the tip thereof is lowered in an atmosphere of an inert gas shield so as to come into contact with the welding base metal and rise after being energized to weld the electrode tip of the welding torch. In an arc start method of generating an arc between a base metal, (1) by lowering the welding torch and applying a voltage of a sub power supply for contact detection between the electrode and the weld base metal,
(2) Detecting that the electrode tip of the welding torch has come into contact with the welding base metal, and at the same time stopping the lowering operation of the welding torch,
(3) After that, apply the voltage of the main power source for welding,
(4) Simultaneously with the start of energization of the initial current or immediately after energization,
There line arc ignition move to separate the electrode tip of the welding torch in contact with the welding base material in an oblique direction, the contact
Tactile detection current is less than 1A, and between the electrode and welding base metal
The range of the initial current applied to the
The separation angle of the electrode tip to the opposite is 20 to 60 degrees, and the height
An arc start method characterized in that it is in the range of 0.5 to 1.5 mm . 2. The operation of pulling apart the electrode tips in an oblique direction is performed by simultaneously driving a vertical drive shaft on which a welding torch is mounted and a horizontal drive shaft or a traveling carriage. Arc start method. 3. When the initial current supplied from the main power source is cut off in the middle, the arc start operation is temporarily stopped, and then the front and rear direction or the left and right direction of the welding line different from the position where the electrode tip is in contact. 2. The arc start method according to claim 1, wherein the welding torch is moved to another position of No. 1, and the arc start operation is restarted from the position after the movement. 4. A welding torch provided with a non-consumable electrode at its tip is lowered in an atmosphere of an inert gas shield to bring it into contact with the welding base metal and raise it after energization to weld the electrode tip of the welding torch. In an arc start method of generating an arc between a base metal, (1) by lowering the welding torch and applying a voltage of a sub power supply for contact detection between the electrode and the weld base metal,
(2) Detecting that the electrode tip of the welding torch has come into contact with the welding base metal, and at the same time stopping the lowering operation of the welding torch,
(3) After that, apply the voltage of the main power source for welding,
(4) Simultaneously with the start of energization of the initial current or immediately after energization,
Move the electrode tip of the welding torch that was in contact with the welding base metal in an oblique direction to perform arc ignition, and (5)
In addition, the electrode tip position of the welding torch after arc firing,
Make sure to raise and move to the steady position within the initial current time or the time until the steady welding current is reached.
The contact detection current to 1 A or less, and
The range of the initial current applied between the base materials is 5 to 50A,
The separation angle of the electrode tip from the welding base metal is 20 to 60
An arc start method characterized in that the degree and the height are in the range of 0.5 to 1.5 mm . 5. A welding torch provided with a non-consumable electrode at its tip is lowered in an atmosphere of an inert gas shield so as to come into contact with the welding base metal and rise after being energized to weld the electrode tip of the welding torch. In an arc starter that generates an arc between the base metal, a traveling carriage that moves in the welding direction by engaging a vertical drive shaft that vertically moves the welding torch and a horizontal drive shaft that horizontally moves the welding torch, and electrodes in the welding torch. It is equipped with a welding power source for energizing for welding and a contact detection power source for detecting electrode contact between the welding base metal and the welding base metal, and the electrode tip of the welding torch is pulled up in an oblique direction after the electrode is contacted with the welding base metal and energized. Perform the arc firing, and move the electrode tip position of the welding torch after arc firing up and down to move up and move to the steady position within the time of the initial current or the time until reaching the steady welding current. A welding control device for controlling the moving shaft, the left and right drive shafts, and the contact detection power supply is provided, and the contact detection current is set to 1 A or less.
The range of the initial current that flows between the electrode and the welding base metal is 5 to 5
At 0A, set the separation angle of the electrode tip to the welding base metal to 2
An arc starter characterized by having a height within a range of 0 to 60 degrees and a height of 0.5 to 1.5 mm .