JPH09155565A - Electron beam welding method and its welding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron beam welding method capable of performing the deep penetration without generating any discharge phenomenon. SOLUTION: At least a first deflection coil 3 and a second deflection coil 4 are arranged between an electron gun 1 and a vacuum welding chamber to deflect the route of the electron beam B to be irradiated from the electron gun 1 by the deflection coils 3, 4, and the route of the electron beam B is an irradiation beam part to irradiate the electron beam from the electron gun 1, a deflected beam part to irradiate the electron beam from the beam part at an appropriate angle θ, and an irradiated beam part to irradiate the electron beam from the deflected beam part to a welded part of the welding metal D so as to prevent the electron gun 1 or the electron beam B from being affected by the metallic vapor, etc., generated from the welded part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam welding method using an electron beam and a welding machine therefor.

[0002]

2. Description of the Related Art When a product is manufactured using an aluminum alloy (hereinafter referred to as an aluminum-based material), it is difficult to weld the aluminum-based material. Means of attaching are often used. Tungsten in suitable for welding non-ferrous metals and alloy steels as a welding means for aluminum-based materials
ert) is used. When aluminum-based material is welded by this TEG welding, as shown in FIG.
A V-shaped or U-shaped groove J (also referred to as a groove) is formed at the joint of D2 and D3, respectively, or a groove J is formed at one of the material joints.
Are formed, the materials D1, D2 and D3 are butted, and the groove J is welded K in an inert gas atmosphere such as helium or argon using tungsten or a tungsten alloy as an electrode.

The reasons why it is difficult to weld aluminum-based materials are as follows. Thermal conductivity is about 4 times that of steel, specific heat is about 2 times that of steel, and latent heat of fusion is about 1.5 times that of steel. That is, despite the low melting point, it is difficult to locally melt, and it is necessary to rapidly supply a large amount of heat. Due to the above properties, the welding base metal is susceptible to wide range welding. Due to its high affinity with oxygen, it is necessary to sufficiently shield the molten pool with inert gas (argon, helium) during welding. When an oxide film is formed, it is thin but hard, dense, and has a high melting point (about 2000 ° C.), which makes it difficult to remove. It prevents the welding base metal and the fusion of the welding base metal and the filler metal. Since the linear expansion coefficient is large (about twice that of steel), welding distortion is also large. Due to the large solidification shrinkage (about 1
5 times), and also has a high solidification cracking susceptibility. Because of its high conductivity, electric resistance welding requires a large capacity power supply. Large amount of hydrogen gas absorption. That is, although the molten aluminum absorbs a large amount of hydrogen gas, the solubility in the solid layer is small (the tendency for pores to be large).

In recent years, it has been attempted to weld an aluminum material using a high energy density heat source such as an electron beam or a laser beam. The electron beam welding method is shown in Fig. 1 (B).
As described above, the welding metal D is irradiated with the electron beam B having a high energy density obtained by accelerating the electrons at a high speed in a vacuum and converging the electrons at a high density to melt and weld the electron beam B. The density reaches 5000 times or more that of arc welding, and when the electron beam B irradiates the weld metal D, the portion instantaneously generates heat, melts, vaporizes, and welds.

The features of the electron beam welding method are as follows. Since welding is performed in a high vacuum (10-4 Torr), no oxide is mixed. High energy density enables high speed welding. Penetration of about 10 mm is possible, and welding can be performed with one welding. The heat effect of the welding base material is small and the base material is not deformed much. Reproducibility is high because it can be managed by numerical control.

[0006]

Since aluminum-based materials have very good thermal conductivity, a large amount of heat input is required for fusion welding. Therefore, the heat change of the base metal due to welding and the inclusion of air during welding are required. There is a problem that the quality of the welded portion is easily deteriorated due to the generation of pores due to the above. In addition, when an aluminum-based material is welded by an electron beam, a discharge phenomenon (also called arcing) is more likely to occur as compared with a steel material,
There is a problem that porous internal defects (also referred to as porosity) in which a large number of minute cavities are present are likely to be caused.

The discharge phenomenon that occurs during electron beam welding is
Although it is closely related to the degree of dirt, it is more closely related to the acceleration voltage, and it is considered that the higher the acceleration voltage, the more sensitive it is to dirt. That is, the lower the accelerating voltage is, the more it decreases, but the lower the accelerating voltage is, the shallower the penetration becomes. On the contrary, the higher the accelerating voltage is and the deeper the penetration is, the more the electric discharge phenomenon occurs, and continuous welding becomes impossible. . As a result, continuous welding was possible only with a wall thickness of about 10 mm.

The discharge phenomenon is induced by the gas component contained in the metal melted by the electron beam, the ionized metal vapor reaching the cathode-anode through the beam path, or the electron gun chamber. It is also considered to be induced by the gas component generated from the foreign matter (oil and fat etc.) that has penetrated into the. Therefore, as the electron gun is contaminated with metal vapor or the like, a discharge phenomenon occurs more frequently, and the beam welding is also temporarily stopped due to the discharge phenomenon, resulting in a problem that the frequency of maintenance becomes high. Moreover, even if the degree of vacuum is adjusted or the electron beam acceleration or the like is adjusted, the occurrence of the discharge phenomenon cannot be reduced.

When a product is cut out from an aluminum-based lump material, there is much waste of expensive material, and the cost increases accordingly, and when forming an aluminum product by TIG welding, it is opened at the welded part of the aluminum-based material. There is also a problem of inefficiency because it requires pre-machining and requires welding of the groove several times. Therefore, the present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide an electron beam welding method and a welding machine therefor capable of deep penetration without causing a discharge phenomenon. To do.

[0010]

In order to achieve the above object, the electron beam welding method of the present invention irradiates the welded portion of the weld metal by deflecting the course of the electron beam emitted from the electron gun from the middle. However, the electron gun and the electron beam are not affected by the metal vapor or the like generated from the welded portion.

In the electron beam welding machine of the present invention, at least the first deflection coil and the second deflection coil are arranged between the electron gun and the vacuum welding chamber, and the path of the electron beam emitted from the electron gun by the deflection coil is arranged. Is deflected from the middle by an irradiation source beam part irradiated from the electron gun, a deflection beam part irradiated from the beam part at an appropriate angle, and an irradiation destination beam part irradiated from the deflection beam part toward the welding part. The electron beam is not affected by the metal vapor generated from the weld.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the basic principle of the electron beam welding method according to the present invention will be described with reference to FIG. 1 (A). The course of the electron beam B emitted from the electron gun 1 is at least deflected by the deflection coils 3 and 4. The beam is deflected halfway, and the irradiation source beam part b1 for irradiating the path of the electron beam B from the electron gun 1, the deflection beam part b2 for irradiating the beam part b1 at an appropriate angle θ, and the deflection beam part b2 for welding metal The irradiation target beam portion b3 for irradiating the welding portion D is formed.

Next, an embodiment of the electron beam welding machine according to the present invention will be described with reference to FIG. 2. A second vacuum chamber 6 is provided under the first vacuum chamber 5 and a vacuum welding chamber 7 is provided under the vacuum chamber 6. Is provided
The electron gun 1 is housed in the first vacuum chamber 5, the lens coil 2 and the first deflection coil 3 are arranged in the middle part of the second vacuum chamber 6, and the second deflection coil 4 is arranged in the lower part, so that a vacuum system for one system is formed. The device 8 is connected to the first vacuum chamber 5, the second vacuum chamber 6 and the vacuum chamber welding chamber 7, or the vacuum device 8 is divided into the vacuum welding chamber 7 and the others and connected to two systems. If the vacuum device 8 is divided into two systems and connected, it is possible to further reduce the metal vapor rate reaching the electron gun 1. It is also possible to configure the first vacuum chamber 5 and the second vacuum chamber 6 as one chamber.

The lens coil 2 is arranged on the path of the beam B emitted from the electron gun 1, and uses an electrostatic lens, a magnetic lens or a collecting electron lens. The first deflection coil 3 is arranged on the path of the beam B emitted from the electron gun 1, and the second deflection coil 4 is arranged at the intersection of the paths of the deflection beam part b2 and the irradiation destination beam part b3. Electrostatic deflection type or electromagnetic deflection type is used for 3 and 4. An inlet / outlet 71 is provided in at least one of the vacuum welding chambers 7, and a door 72 is provided at the inlet / outlet 71 so as to be openable / closable and sealable.
The workbench 73 is moved in and out through the doorway 71.

A column valve 61 and an orifice 62 are provided above the second vacuum chamber 6, and a mirror 63 for observing a welding state and a CCD (charge coupled device ca) are provided in the second vacuum chamber 6 below the first deflection coil 3.
It is desirable to include a mera 64. For the vacuum device 8, for example, a rotary pump, a mechanical booster pump, a diffusion pump or the like is used.

Since the electron beam welding method and the welding machine therefor according to the present invention are as described above, first, the welding metal D is placed on the work table 73, and the work table 73 is placed inside the entrance 71 of the vacuum welding chamber 7. , The door 71 is closed by the door 72, the vacuum device 8 is activated, the vacuum welding chamber 7 and the vacuum chamber 5,
6 is evacuated. Next, when the electron beam B is radiated from the electron gun 1 toward the weld metal D, the electron beam B radiated from the electron gun 1 is first radiated by the radiation source beam part b1 along the radiation direction of the electron gun 1, Deflection beam portion b is set at an appropriate angle θ from irradiation source beam portion b1 by deflection coils 3 and 4.
2, and the irradiation target beam part b3 irradiates the weld metal D from the deflected beam part b2.

Since the electron beam B radiated from the electron gun 1 is deflected and radiated to the outside of the irradiation portion of the electron gun 1, even if the metal vapor diffuses from the welded portion due to the beam welding, the generated metal vapor is generated. It is quickly recovered by the vacuum device 8 and does not reach the deflected electron gun 1 from the welded portion. As a result, the influence of the metal vapor or the like on the electron gun 1 and the electron beam B is reduced, and the discharge phenomenon due to the metal vapor (including the dielectric breakdown due to the metal vapor or the abnormal phenomenon of the overcurrent) is significantly reduced. The voltage can be increased and the power of the electron beam B can be increased.

[0018]

EXAMPLES An electron beam welding machine according to the present invention (hereinafter referred to as D-
KM) and conventional electron beam welder (hereinafter, S-T)
The welding state according to (E) is compared. D-KM and S
-TE performance is shown in Table 1.

[Table 1]

The welding conditions for D-KM and S-TE are shown in Table 2.

[Table 2]

As a weld metal D (referred to as a test metal in the examples) used for electron beam welding, A5052 is used.
Using a (JIS) aluminum alloy, the test metal D1 to the test metal D3 have a thickness t of 50 mm, a width S of 23 mm, and a length L of 3
The test metal D4 has a thickness t of 50 mm and a width S of 2
3mm and length L is 69mm. The test metals D1 to D3 are sequentially beam-welded in parallel as shown in FIG. 5, one of them is beam-welded again to form the irregular beads E generated by the beam welding as the decorative beads F, and then the beams are beamed in parallel. The test metal D4 was beam-welded to one end of the welded test metal D1 to test metal D3. In order to compare the penetration of the beam welding in the joints of the test metals D1 to D4 and the penetration of the beam welding in the portions other than the joints, as shown in FIG. And electron beam B was irradiated. This is called test welding T.

When the appearances of the test metals D1 to D4, which were electron beam welded by the D-KM, were visually observed, the penetration penetrated from the beam irradiation side to the opposite side as shown in FIG. Except for the cosmetic beads F, a considerable amount of spatter (slag and metal particles scattered during beam welding) was found around the beads E on the beam irradiation side, and the beads E were irregular. This is probably because the metal vapor generated by the beam heating was blown out of the molten metal that had flowed in when it rose through the narrow and deep beam hole.

Observing the appearance of the test metals D1 to D4 which were electron beam welded by S-TE, the beads E on the beam irradiating side were not conspicuously irregular as shown in FIG. 11, but melted on the opposite side. It can be seen that the irradiation of the electron beam B has not reached 50 mm because there is no trace of the penetration. Since the bead width is slightly thicker than D-KM, it is considered that the energy loss of the beam B is large. Also, the oxidation was remarkable.

The test metals D1 to D3, which were electron beam welded by D-KM, were longitudinally cut along C1 as shown in FIG. 6, and the penetration depth at the cut surface C1 was measured. A parallel penetration was formed up to about / 4, and the penetration depth reached about 50 mm as shown in FIG. It is considered that this is because the energy loss of the beam B at the initial stage of heat input (surface of the object to be welded) is small and the beam hole is deeply formed due to the high accelerating voltage and the output characteristic of the beam B. From this, it can be understood that deep penetration can be obtained with a small heat input amount.

The test metals D1 to D3 electron-beam welded by S-TE were replaced with C1 in FIG. 6 in the same manner as described above.
When the depth of penetration in the cut surface C1 was measured, the bead E was thick as shown in FIG. 14 (A), and was gradually tapered toward the tip of the bead E. Although the penetration depth reaches about 40 mm, the energy loss of the beam B on the metal surface d becomes large, and it is considered that deep penetration cannot be obtained. The S-TE accelerating voltage is set lower than the D-KM because, due to the structure, when the accelerating voltage is increased to 120 KV or more, electric discharge occurs near the electron gun 1 and beam welding becomes difficult. .

In the test metals D1 to D4, the intersections of the two beams B were cut along the line C2 in FIG. 6, and the penetration depth at the cut surface C2 was measured. In that case, as shown in FIG. 13, the macrostructure had a porous welding defect at the tip of the bead E, but no porous welding defect was found in the vicinity of the boundary with the intersecting bead E. FIG. 14 for S-TE
As shown in (B), no defect was found in the vicinity of the boundary with the intersecting bead E.

When the welded portion of the test metal D2 and the test metal D3 which were electron beam welded by the D-KM was cut as indicated by C3 in FIG. 7 and the internal defect at the cut surface C3 was measured,
As shown in FIG. 15, block-shaped porous welding defects were almost regularly distributed in the welding direction at the tip of the decorative bead F.
Porous welding defects are found in the range of 45 to 50 mm from the metal surface d. It can be seen that the beam B is stably irradiated in the welding direction. Further, the effective range for the joint portion is about 40 mm after removing the porous welding defect at the tip of the bead E and the surface of the bead E.

The welded portions of the test metal D2 and the test metal D3 which were electron beam welded by S-TE were cut along the line C3 in FIG. 7 in the same manner as described above, and the internal defects at the cut surface C3 were measured. At the tip of F, slender linear porous welding defects were distributed in the deep melting direction as shown in FIG. Porous welding defects are 25-40 from the metal surface d
In the range of mm, the decorative bead F has two layers of porous welding defects, and the effective range as a joint joint is 2
It is 4 mm or less.

When microscopic cracks of the test metal D1 to the test metal D4 welded by electron beam were measured, the D-KM tends to be seen at the tip of the bead E during solidification of the molten metal as shown in FIG. 8 (A). There were few microcracks. S-
In TE, as shown in FIG. 8 (B), many microcracks are seen at the tip of the bead E, so when used as a joint joint, these are removed together with a porous welding defect at the tip of the bead E. Must.

As a result of the experiment, comparing D-KM and S-TE, as shown in Table 3, D-KM is superior to S-TE in terms of stability of the bead E, penetration depth, internal defects and the like. I understand.

[Table 3]

The porous welding defect generated at the tip of the bead E can be removed later by cutting, so that it does not cause any problem. In beam welding of a large product, the irradiation position of the beam B is taken into consideration and a joint position and the like need to be devised.

When a test metal D of aluminum alloy A5052 (JIS) was irradiated with an electron beam B under the following conditions, continuous beam welding could be performed without interruption. Acceleration voltage 150 KV Welding current 100 mA Welding speed 100 mm / min Vacuum degree (5 × 10 −4 Torr) Penetration depth reached 100 mm or more as shown in FIG.

The workbench 73 that enters and exits through the inlet / outlet 71 of the vacuum welding chamber 7 is mounted with the weld metal D outside the welding chamber 7, the workbench 73 travels inside the welding chamber 7, and the inlet / outlet 71 of the welding chamber 7 is installed. After the work is shielded, the workbench 73 is finely adjusted by remote control so that the welding metal D matches the irradiation position of the electron beam B. The deflection angle θ of the electron beam B is mainly determined by the first deflection coil 3 and the second deflection coil 4.

[0033]

The electron beam welding method of the present invention and the welding machine therefor have the above-described structure, and therefore have the following effects. Alloys containing components such as tin, zinc, and magnesium, which are difficult to e-beam weld and easily evaporate (hereinafter,
It is possible to perform ultra-precision welding of non-ferrous metal materials, such as aluminum-based materials, from thin plates to thick plates (0.1 to 120 mm), and with a single beam welding, a penetration depth of 100 mm or more can be obtained. As a result, the manufacturing efficiency of non-ferrous metal products can be improved and the cost can be reduced. Furthermore, since the beam welding is performed in a vacuum, it is possible to perform uniform beam welding in which the non-ferrous metal base material does not contain impurities, prevent deterioration of electrical efficiency due to corrosion, and improve quality.

Compared with general welding, the groove processing for the metal base material is not required and the number of beam welding for the continuous portion is significantly reduced, so that the processing cost can be reduced. Moreover, reproducibility and reliability of beam welding are great. It can cope with an increase in the number of products manufactured. Material cost is low compared to the machined product, and it does not take time to obtain the thick plate. Moreover, the machining cost is low and the delivery time can be shortened. Compared with die forging, it does not require die cost and can respond to design changes. Moreover, the starting of the first rod is quick (because no mold is required).

The electron beam welding according to the present invention is used for beam welding of metals which have been conventionally electron beam welded, such as stainless steel, carbon steel, low alloy steel, copper, nickel alloy, zirconium, titanium, molybdenum and tungsten. Of course, it is especially effective for electron beam welding, which has been difficult to obtain in the past, for example, non-ferrous metal-based beam welding containing components such as tin, zinc, and magnesium that easily evaporate, and beam welding of special metals. To do.

As a result, the electron beam welding according to the present invention is used in space / aircraft fields, electric / electric power fields, chemical / steel manufacturing fields, plant / machine fields, and composite materials, for example, valves, turbine blades, filters, gyro tubes, It has a remarkable effect in manufacturing rotors, impellers, pump parts, gear couplings, liners, rolls, flanges, gears, rolled clad, clad pipes, pressure vessels, and vacuum vessels. Especially semiconductor manufacturing equipment and LC
This is optimal because the material is changing from stainless steel to aluminum-based material with the increase in size of ultra-high vacuum chambers (also called vacuum vessels) used in the field of D (color liquid crystal display) manufacturing.

[Brief description of the drawings]

1A and 1B are comparison diagrams of an electron beam welding method according to the present invention and a conventional electron beam welding method.

FIG. 2 is a schematic view showing a basic structure of an electron beam welding machine according to the present invention.

FIG. 3 is a side view showing a welding example of (A) and (B) electron beam welding.

FIG. 4 is a side view showing a conventional welding example.

FIG. 5 is a perspective view showing an example of beam welding of a test metal.

FIG. 6 is a perspective view showing a measurement position of a penetration depth by an electron beam.

FIG. 7 is a perspective view showing measurement positions of internal defects.

8A and 8B are perspective views showing a melted state by beam welding.

FIG. 9 is a comparative perspective view of arc welding, laser welding, and electron beam welding.

FIG. 10 (A) and (B) are external appearance photographs on the side opposite to the beam irradiation side, showing the welding state by D-KM.

FIG. 11 (A) and (B) are external appearance photographs on the side opposite to the beam irradiation side, showing the welding state by S-TE.

FIG. 12 is a cut surface C showing a melted state by D-KM.
It is a photograph of 1.

FIG. 13 is a cut surface C showing a state of penetration by S-TE.
It is a photograph of 1.

14 (A) and (B) are photographs of a cut surface C2 showing a melted state of a beam intersection portion by D-KM and S-TE.

FIG. 15 is a photograph of a cut surface C3 showing a melted state of a cosmetic bead portion by D-KM.

FIG. 16 is a photograph of a cut surface C3 showing a melting state of a decorative bead portion by S-TE.

FIG. 17 is a photograph showing an example of electron beam welding according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Electron gun 2 Lens coil 3,4 Deflection coil 5,6 Vacuum chamber 7 Vacuum welding chamber 8 Vacuum device B Electron beam b1 Source beam part, b2 Deflection beam part, b3 Target beam part E Bead, F Cosmetic bead D, D1, D2, D3, D4 Weld metal (test metal),
a Metal surface C1, C2, C3 Cut surface A Arc weld, G beam weld, R Laser weld T Test welding θ Beam deflection angle

Claims (3)

[Claims] 1. An electron beam welding method in which the course of an electron beam (B) emitted from an electron gun (1) is deflected from the middle to irradiate the welded portion of the weld metal (D). 2. At least a first deflection coil (3) and a second deflection coil (4) are arranged between the electron gun (1) and the vacuum welding chamber (7), and the deflection coils (3, 4) are used. The course of the electron beam (B) emitted from the electron gun (1) is deflected from the middle so that the electron gun (1) and the electron beam (B) are not affected by metal vapor or the like generated from the welded portion. Electron beam welder. 3. The path of the electron beam (B) emitted from the electron gun (1) is set at an appropriate angle from the irradiation source beam portion (b1) emitted from the electron gun (1) and the beam portion (b1). 3. The electron beam welding machine according to claim 2, comprising a deflected beam portion (b2) for irradiating with θ) and an irradiation destination beam portion (b3) for irradiating the welded metal (D) from the deflected beam portion (b2).