JPS6050550B2 - Manufacturing method of closed hollow body by welding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a closed hollow body having a relatively narrow internal space by welding.

An example of this type of closed hollow body is the propeller shaft of an automobile. An automobile propeller shaft is generally made of a hollow steel tube with a universal joint yoke connected to both ends. To connect a yoke to a hollow steel pipe, fit the yoke properly to both ends of the hollow steel pipe, and then support the entire body at both ends to the extent that it can be rotated appropriately by a pressurizing center, and then slowly loosen the whole thing. A widely used method is to continuously arc weld the part while rotating the part. However, as the hollow steel pipe and yoke are welded together, the air inside the hollow steel pipe sealed by the yoke expands, so if welding is performed in a sealed state, welding defects (blowholes) are likely to occur on the heated surface, which may occur later. This will require some rework. Regarding this point, conventionally, a ventilation hole was formed in a part of the yoke that was not blocked by the pressurizing center, and this ventilation hole was used to allow circulation between the internal air and the outside air.
However, since the position that is not blocked by the pressurization center is located off the center line of the propeller shaft, care must be taken to ensure that the rigidity and rotational characteristics of the propeller shaft do not change even when the ventilation hole is formed. be. For this reason, in the case of propeller shafts, it is necessary to close the ventilation holes after welding is complete. Furthermore, even if there is a hollow body other than the propeller shaft, there are some in which the ventilation hole cannot be made anywhere other than on the center line of the hollow body. Even if the hollow body is cylindrical, it is difficult to weld the hollow body while rotating it using a pressure center, and therefore the efficiency of the welding operation is low. In view of the above-mentioned conventional problems, the present invention provides a closed hollow body that can utilize a pressurization center to circulate internal air and outside air without impairing the overall balance of the closed hollow body. The purpose is to provide five manufacturing methods by welding.

Next, the configuration of the present invention will be specifically described based on embodiments shown in the drawings.

FIG. 1 shows, as an application example of the present invention, the relationship between the most common automobile propeller shaft and a pressure center, which is a tool that supports it.

The propeller shaft as a sealed hollow body includes a hollow steel pipe 1 as a body, and front and rear (left and right in the drawing) yokes 2 as welded joint members connected to both ends of the hollow steel pipe 1.

After fitting the boss portions 3 of the front and rear yokes 2 to both ends of the hollow steel tube 1, the front and rear yokes 2 are fitted at the joint portion between the edge of the hollow steel tube 1 that appears on the outer periphery and the stepped portion of the boss portion 3 of the yoke 2. It is welded. One of the front and rear yokes 2 (first
In the left side (in the figure), a ventilation hole 4 is bored in the center. The vent hole 4 is perfectly circular, and its center is on the center line of the propeller shaft. During temporary assembly, the propeller shaft, in which the yoke 2 is fitted to both ends of the hollow steel pipe 1, is assembled by welding the hollow steel pipe 1 and the yoke 2 together.As shown in FIG. The book is supported by the tips of the pressure centers 5, 5A and held in a substantially horizontal state. A pressurizing center 5 that supports the side of the yoke 2 having the ventilation hole 4 has two communication grooves 6 formed along the generatrix line, leaving the leading edge, at its conically pointed tip. However, the number of communication grooves 6 is not a particular problem. Therefore, the number of communication grooves 6 may be one, or three or more. As shown in FIG. 1, the relationship between the grooved pressure center 5 and the ventilation hole 4 is that the pressure center 5 has a larger diameter; On the other hand, it is possible to penetrate about halfway between the tip. To support the temporarily assembled propeller shaft on the pressurizing centers 5, 5A, insert the tip of one grooved pressurizing center 5 into the ventilation hole 4 of the yoke 2, and insert the tip of the other pressurizing center 5A. All you have to do is press it against the center of the yoke 2 on the other -3 side. This operation is easy because the yoke 2 has a vent hole 4 formed therein, and the propeller shaft can be stably supported by the pressurizing center 5 by the vent hole 4. In this way, the propeller 4 lash shaft supported by the pressurizing centers 5, 5A,
The hollow steel pipe 1 and each yoke 2 are welded by the torch 7, which is rotated slowly in one direction and adjusted to the location where welding is required. During this welding, the air inside the propeller shaft expands thermally, but since the air inside the propeller shaft communicates with the outside air through the ventilation hole 4 and the communication groove 6 of the pressurizing center 5, the pressure inside the propeller shaft increases. is not high and the welding condition is good. After welding is completed, the ventilation hole 4 of the yoke 2 is sealed, because if the ventilation hole 4 is left open, noise will be generated due to the high speed rotation of the propeller shaft, so it is not necessary to seal the ventilation hole 4 of the yoke 2. It is not intended to deal with changes in propeller shaft stiffness or rotational characteristics.
Also, sealing the vent hole 4 is easy because the vent hole 4 is located on the center line of the propeller shaft, and the characteristics of the propeller shaft itself will not change significantly even if there are variations in the sealing process. . As is clear from the description of the embodiments, the present invention has a vibrator-like body part with at least one end open, and a body part which is welded to the open end of the body part in the form of a closed lid. Regarding the hollow body consisting of a welded joint member, a small hole is passed through approximately the center of at least one welded joint member before welding, and when welding the body part and the welded joint member (above), proper assembly is required. Among the supporting tools that support the hollow body in the attached state at approximately the center of both ends while allowing appropriate rotation, those that are fitted into the small holes of the welded joint members have a tip with the small hole extending outward. Since this is a manufacturing method by welding a closed hollow body that uses a communication groove that can be opened, unlike the conventional technology in which a ventilation hole is provided at a location away from the support part of the support tool, a rotating hollow body is used. In this case, it is easier to consider the overall rigidity and balance, and in the case of a hollow body in which the shaft is passed through the center, the hole for passing the shaft can be used as a small hole for ventilation. Something will happen. For any of these types of hollow bodies, good welding can be performed efficiently by using a support tool.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIG. 1 is a schematic front view, partially in cross section, showing a state of welding a propeller shaft as an application example of the present invention. FIG. 2 is a front view of only the main parts showing only the pressurizing center on the left side of FIG. 1, and FIG. 3 is a view taken in the direction of arrow 2 in FIG. 1...
...Hollow steel pipe, 2...Yoke, 4...
...Vent hole, 5...Pressure center, 6...
・Communication groove.

Claims (1)

[Claims] 1. A method for manufacturing a hollow body consisting of a pipe-shaped body with at least one end open, and a welded joint member welded to the open end of the body in the form of a closed lid, the method comprising: A small hole is passed through approximately the center of at least one welding joint member, and when welding the body and the welding joint member, the hollow body in a properly assembled state is allowed to rotate moderately and approximately at both ends. Among the supporting tools supported at the center, those fitted into the small holes of the welded joint members should have communication grooves at their tips that can open the small holes to the outside. A method for producing a closed hollow body by welding, characterized by: