JPS61238480A - Production of shaft material - Google Patents

Abstract

PURPOSE:To make possible the satisfactory welding at the joint ends of a pair of shaft parts down to the central part by providing respectively through-holes to the side end faces of the round bar-shaped joint part of said parts, inserting a backing bar therein and irradiating an electron beam parallel with the joint side end faces thereon while rotating the shaft parts. CONSTITUTION:The through-holes 6 are respectively provided at the center of the joint end face 8 of a crank member 3 and the joint end face 5 of a main bearing part 4. The end faces 5, 8 are butted to each other and the backing bar 7 is inserted into the hole 6. While the assembled shaft member 10 is rotated, the electron beam 9 parallel with the end faces 5, 9 is irradiated on the joint part to melt and weld said part down to the central part. The arrival of the electron beam end at the opposite side is prevented by the bar 7 and therefore in full-surface welding without weld defects is made possible even with the large-sized shaft material.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method of manufacturing a shaft part by coaxially joining large-diameter shaft parts, and is particularly suitable for application to a crankshaft.

<Conventional technology> Manufactured by shape or integral forging.

<Problems to be solved by the invention> The shaft diameter and overall length of the crankshaft of an internal combustion engine for large ships are incomparably larger than the dimensions of a common internal combustion engine crankshaft. However, the cost would be extremely high or production would be impossible.

The present invention has been made based on this knowledge, and an object of the present invention is to provide a method for manufacturing shaft objects such as large crankshafts easily and at low cost.

Means for Solving the Problems> In the method for manufacturing a shaft of the present invention, a through hole is provided at the center of a pair of shaft components each having a round bar shape, and the side end surfaces of these shaft components are opposed to each other to form a through hole. A backing rod is inserted into the hole, and an electron beam parallel to the side end surface of the shaft part is irradiated onto the backing rod side, and the electron beam and the shaft part are rotated relative to each other, so that the aI end of the shaft part 3 is Tomomi Omengaki+r
It is characterized by a door.

Function> By irradiating the electron beam from the outer peripheral surface of the shaft component to the backing rod side at the center, the side end surfaces of the shaft component are electron beam welded to each other and function as one shaft component. Since the through hole is formed, the central part of the shaft component, where welding quality deteriorates, will not be welded, and a good welded part can be obtained.

Embodiment Fig. 1 shows the working concept of an embodiment in which the present invention is applied to the manufacture of a crankshaft, and Fig. 2 shows its cross-sectional shape in the direction of the
As shown in the figure, there are a plurality of crank members 3 in which pins 1 to which connecting rods (not shown) are attached are fixed to the tips of a pair of cranks 2, and a main bearing part 4 interposed between these crank members 3. and arrange them in a predetermined =)N- group. A joint end surface 5 having approximately the same diameter as the main bearing part 4 is formed at the joint part of the crank member 3 with the main bearing part 4, and a through hole 6 is provided in each joint part. Then, a backing rod 7 is inserted into this through hole 6, and the joining end surface 5 of the crank member 3 and the joining end surface 8 of the main bearing portion 4 are electron beam welded using an electron gun 9. The electron beam 11 is irradiated from the outer peripheral surface of the main bearing portion 4 toward the center in parallel with these joint end surfaces 5 and 8,
It is performed in the same manner as circumferential welding. After welding is completed, the backing rod 7 is removed from the through hole 6, and the crankshaft 10 is manufactured in this way. Note that a vacuum vessel necessary for electron beam welding is not shown.

Since the through hole 6 is formed in the center of the crankshaft 10, there is no risk of welding defects remaining in this center, and the tip of the electron beam 11 can be inserted into the through hole 6 in the center of the crankshaft 10. Since the inserted backing rod 7 does not reach the opposite side, a high-quality crankshaft 10 without welding defects can be manufactured. Incidentally, electron beam welding is a welding method that causes less thermal distortion during welding, so it is highly effective.

Since the method of the present invention allows large members to be divided into small pieces and joined together, the quality of each forged part can be improved, and shaft parts such as crankshafts of a size that is impossible with integral forging can be easily produced.

Further, in the above-described embodiment, the crank member 3 and the main bearing portion 4 are welded by electron beam, but the pin 1 and the crank 2 may be welded by electron beam in the same manner.

<Effects of the Invention> According to the present invention, by inserting a backing rod into a through hole formed in the center of a pair of shaft parts and electron beam welding the side end surfaces of the shaft parts, a large shaft part can be manufactured. It is also of good quality and easy to manufacture.

[Brief explanation of the drawing]

FIG. 1 is a working conceptual diagram of an embodiment in which the present invention is applied to a crankshaft, and FIG. 2 is a cross-sectional view taken along the line ■-■. 3 is a crank member, 4 is a main bearing portion, 5 and 8 are joint end surfaces,
6 is a through hole, 7 is a backing rod, 9 is an electron gun, 10 is a crankshaft, and 11 is an electron beam.

Claims (1)

[Claims] A through hole is provided in the center of each of a pair of shaft parts having a round bar shape, and a backing rod is inserted into the through hole with the side end surfaces of these shaft parts facing each other, and an electron beam parallel to the side end surfaces of the shaft parts is inserted. A method for manufacturing a shaft member, characterized in that the electron beam is irradiated onto the backing rod side, and the electron beam and the shaft member are relatively rotated to join the side end surfaces of the shaft member to each other.