JPS60203373A - Electron beam welding method - Google Patents

Abstract

PURPOSE:To perform butt welding without a defect such as a defective bead shape at the beginning and terminal ends of butt welding by positioning the focus of an electron beam upper or lower than the surface of members to be welded at the beginning end and terminal end of butt welding and welding said members. CONSTITUTION:The focus of an electron beam 3 is positioned upper or lower than the surface of materials 1, 1 to be welded at both ends of a butt part and welding is performed by matching the focus to the surface in the intermediate part in the stage of fixing the materials 1, 1 by means of clamps 6 via spacers 5, a backing strip 4, etc. and subjecting said materials to but welding by the beam 3. The generation of a welding defect such as the run at the beginning end, the keyhole at the terminal end, etc. is thus prevented without using an end tab and the good bead shape is easily obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to welding using an electron beam, and more particularly to an electron beam welding method for performing two butt welds without attaching end tabs.

[Prior Art and Its Problems] Electron beam welding, which has a high energy density, allows deep penetration and penetration welding in one pass, and is widely used for butt welding of steel plates.

For example, the cylinder 457 (φ: diameter) x 19 (t: thickness) x 31 shown in Photo 3 on page 41 of Welding Technology August 1982 issue [Current status of practical application of electron beam welding] by Mitsuo Kono, Archipelago Kikai
24 (It: length), unit: mm.

In longitudinal joint welding, as shown in Figure 1, as with other welding methods, end tabs 2 are attached to both ends of the butt part of the welded material 1 by tack welding before welding, and the start and end ends of the bead are This prevents welding defects from occurring.

Therefore, much time and labor is required to remove the end tabs by gas cutting or hammering after tack welding and electron beam welding, and labor saving is strongly desired.

[Object of the Invention] An object of the present invention is to provide an electron beam welding method that can butt weld two members without using end tabs.

[Technical background of the invention] In butt welding of two members, end tabs are used to prevent welding defects such as irregular cracks in the bead shape that occur at the start and end of the bead, and to prevent gaps and misalignment at the butt part. were attached to both ends of the butt part.

The welding then started on the end tab and ended on the end tab at the end of the bead. If an end tab is not used, the beam output at the start of the bead is gradually increased to the beam output required for penetration welding while the workpiece is stopped, so the beam is irradiated at the same location and the molten metal is deposited on the surface of the part. A flow of water occurs.

Since electron beam welding is a linear heat source welding method that joins while maintaining the beam hole, a keyhole remains at the end of the bead when the beam output is stopped. If the beam power is gradually lowered, the keyhole will disappear, but defects due to insufficient welding will occur.

Therefore, as a result of various studies, the present inventors have found that the bead shape can be improved by changing the convergence of the electron beam on the surface of the welded material. We have obtained new knowledge that by changing the bead quality at the start end and keyholes at the end end can be prevented. The present invention is based on this knowledge.

[Structure of the Invention] In butt welding two members using an electron beam, welding is performed by positioning the focus of the electron beam above or below the surface of the workpiece at the start and end of the weld.

The present invention will be described below with reference to the drawings.

FIG. 2a is a plan view showing an arrangement of materials to be welded for implementing the electron beam welding method of the present invention in one embodiment;
The figure is a sectional view taken along the line A--A in Figure 2a, and Figure 3 shows the focal position of the electron beam during welding and the welding position of the workpiece.

Reference numeral 1 denotes a material to be welded butt-welded by an electron beam 3, and the butt surfaces are set by a clamp 6 via a backing material 4 placed on the back surface of the material to be welded 1 and a spacer 5.

The focal position of the electron beam 3a at the start of welding at the bead starting end is set above the surface of the material to be welded 1, the beam 3a is irradiated onto the backing material 4, and welding is started.

At the starting end of the bead, the beam 3a is out of focus with respect to the back surface of the welded material 1, and the bead width becomes wider, but the molten metal is less likely to flow.

After welding the starting end of the bead, welding is performed using the beam 3b whose focus position is adjusted to be on the surface of the material to be welded 1.

The depth of penetration is the deepest when the focal point of the beam is on the surface of the material to be welded, resulting in good beam focusing and a bead shape with a narrow bead width.

Next, at the end of the bead, welding is performed using the beam 3c whose focus position has been changed to above the surface of the material to be welded 1, and the beam 3c is moved to a position where the true material 4 is irradiated to complete the welding.

In this way, by appropriately changing the focal position of the beam and performing welding, it is possible to obtain a good bead shape with no defects at both ends of the butt portion.

Note that the same effect can be obtained even if the focus position of the beam at the welding start and end portions is set below the surface of the welded material.

[Example] As a result of butt welding under the conditions shown in Table 1 below, the present invention was able to obtain a good welded portion without any defects.

4- ■Surface of the welded material■15 to 20 mm above the surface of the welded material [Effects of the invention] As described above, according to the present invention, in butt welding of plates, a good welding process without end tabs and no welding defects at the start and end of the bead can be achieved. A bead shape is obtained.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the arrangement of materials to be welded when butt welding plates by the conventional method using end tabs. FIG. 2a is a plan view showing an arrangement of materials to be welded according to one embodiment of the present invention, and FIG. 2b is a cross-sectional view taken along the line A--A in FIG. 2a. FIG. 3 is an explanatory diagram showing the focal position of the beam and the welding position of the material to be welded. 1: Material to be welded 2: End tabs 3.3a, 3b, 3c: Electron beam 4: Trunk material 5 Varnish spacer - 6: Clamp W: Welding direction -7 = Child 1 Figure 3 Figure 8 Section 2b Procedure amendment ( Spontaneous) May 23, 1981 1, Incident Indication 1981 Patent Application No. 060334 2
, Title of the invention Electron beam welding method 3, Relationship with the amended person's case Patent applicant address 2-6-3 Otemachi, Chiyoda-ku, Tokyo Name (6
65) Nippon Steel Corporation Representative Takeshi 1) Yutaka 4, Agent 103 Phone: 03-864-6052
Address: 2-27-6-5 Higashi Nihonbashi, Chuo-ku, Tokyo, Subject of amendment: Column 6 for detailed explanation of the invention in the specification, Contents of amendment 1- 2-

Claims (1)

[Claims] In butt welding of two members using an electron beam: Welding is performed by positioning the focus of the electron beam above or below the surface of the workpiece at the start and end of the welding. Electron beam welding method.