JPH0426952B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stud welded body in which two elongated members are stud welded end to end to provide a weld that is stronger than the strength of the members themselves, and a method for manufacturing the same.

Stud end welding techniques are known in the art and provide a method for welding two parts together by passing a high current density current through one of the two parts to create an arc between the two parts. That is, the generated arc heats and melts the welding surfaces of the two members, presses the two members together, and solidifies the molten metal to weld the members together. Further, for stud welding, an arc stud welding method and a capacitor discharge type stud welding method are used.

One of the most common methods of known stud welding involves implanting an elongated stud into a substantially flat metal member, such as a metal plate. When this is done by arc stud welding, an arc shield is used and an overlay is formed during the welding process. This reinforcement provides a good weld and generally a stronger weld than the stud itself. On the other hand, in the case of capacitor discharge type stud welding, the weld is not necessarily as strong as in the case of arc stud welding, so a flange is provided at the end of the stud to widen the weld surface and flatten it. The strength of the welded part can be increased by welding it to a solid plate. In this way, in stud welding using the capacitor discharge stud welding technique, it is possible to obtain a weld having a weld strength greater than that of the stud itself.

Another example of stud welding is when it is desired to stud-weld the ends of two elongated members, such as bolts, together. Traditionally, stud ends have been welded together by forming a predetermined weld surface on the end of one stud and a flat weld surface on the other stud. In these methods, if the cross-sectional shapes of the studs are the same, the weld formed extends approximately transversely to the longitudinal axis of the stud, and the weld joint area is equal to the cross-section of the two studs to be welded. equal to area. Due to unavoidable problems such as blowholes and contamination in the weld area, the total weld joint area and therefore the strength of the resulting weld will be somewhat weaker than the strength of the stud itself. Therefore, when subjected to torsion or tensile stress, bolts of this type that are welded end to end are generally prone to breaking at the weld.

To date, when it is necessary to weld two bolts end to end together to form a weld with a strength greater than or equal to the strength of the bolts themselves, the ends of the two bolts to be welded are It was necessary to expand the welding area by adding a flange to the part. The provision of a flange can increase the strength of the weld beyond that of the bolt itself, but on the other hand, the cross-sectional area of the weld area or, in the case of round bolts, its diameter is larger than the rest of the bolt. Also, this type of welding method is often not available, since the welded product would be unusable if the bolt had to pass through an opening or hole with a diameter comparable to the cross-sectional area of the bolt itself. Therefore,
It has been desired to develop a stud welding method and product in which the weld has greater strength than the bolt itself and is no larger than the circumferential contour of the bolt itself.

There is a special need for a stud welding method that allows two bolts to be welded end to end, with the diameter of the weld being the same as the diameter of the bolt, but with the weld being stronger than the bolt itself. An example is the fastening member known as a bolt in the aircraft fastening industry.

A tightening member such as a bolt has a bolt head and a smooth bolt shaft, and the end of the bolt shaft is provided with multiple locking grooves. A detachable shank with a tension groove extends from the area of reduced cross section, called the fracture neck. When using a cross bolt, the bolt is inserted into a hole in the parts to be secured together, and a collar is fitted onto the bolt from the end opposite the bolt head. A special tool is then used to pull the shank to be separated and at the same time crush the collar located in the area of the locking groove.

When a tensile force is continued to be applied to the bolt through the shaft portion to be separated, the collar is crushed and firmly locked in the locking groove of the bolt shaft portion of the hatch bolt. The breaking neck is designed to adjust the amount of tension and thus the clamping force applied via the bolt to the two parts to be clamped together.
When the tension increases to the breaking point of the fracture neck of the bolt, the shank to be severed breaks and is separated from the bolt shank. In this way, the tension in the clamping members is adjusted to the point of failure intended to break the fracture neck, thus ensuring a uniform clamping force of any clamping member against the members to be clamped together.

The hack-shaped clamping element consists primarily of titanium. The price of titanium has become very high, and its availability has also become a problem. Conventionally,
The hack-shaped clamping element was made entirely of titanium, ie the shank to be separated was made of the same material as the bolt shank. In view of the cost of titanium material and its availability, there are concerns regarding reusing the cut-off shank in a newly manufactured bolt or welding or fixing a cut-off shank made of relatively cheap material to a newly manufactured bolt. efforts have been made.

It has been proposed in the past that a relatively cheap material, such as a steel-based material, be used for the shaft part of the hack-shaped tightening member that is separated, and then welded to the main bolt shaft part, but the conventional welding method In this case, it is not possible to obtain a welding strength sufficient to ensure that the hack-shaped tightening member breaks at the fracture neck rather than at the welding site, and therefore it is not possible to obtain a product that can be put to practical use.

It is therefore an object of the present invention to provide a weld between two elongated members having the same external contour as these members, but with a welding contact area greater than the cross-sectional area of the two members to be welded, and to reduce the strength of these members themselves. An object of the present invention is to provide a stud welding method having a welding strength equal to or greater than , and a stud welded body manufactured by this method.

The purpose of this is, according to the invention, to form on one of the parts to be welded together a welding surface with a welding contact area larger than the cross-sectional area of these parts, and on the other part to form a welding surface which has a welding contact area made on said one part. This is achieved by forming a welding surface with a shape complementary to the shape of the surface. In this way, the weld contact area in the weld region of the two parts is greater than the cross-sectional area of these parts, so that the strength of the weld is greater than or equal to the strength of the bolt itself.

The shapes of the welding surfaces of the two members may be complementary truncated cones, or one may be concave and the other convex. Further, a protruding welding tip is provided on the welding surface of one of the members. The welding can preferably be carried out by a capacitor discharge stud welding method.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings regarding an embodiment in which a shaft section of a hack-shaped tightening member is welded to a bolt shaft section.

FIG. 1 shows a conventional hack-shaped clamping member, which comprises a bolt shank 10 and a bolt head 11 at one end thereof. The bolt shaft portion 10 is provided with multiple locking grooves 12.

The hack-shaped tensioning element is also provided with a break neck 13, which has a narrow cross-sectional area and, as mentioned above, determines the tension when tightening the tensioning element.

A detachable shaft 14 extends from the fracture neck 13 and is provided with a double tension groove 15 in which a tension caulking tool used for tightening and securing the tensioning member is engaged.

According to the present invention, the shank portion 14 cut off from the hatch bolt can be welded to a newly made hatch bolt that extends slightly beyond the fracture neck 13 and terminates therein. Such weldable parts are marked with numeral 1 in Figure 1.
6. Additionally, a separate cut-off shank 14 made of a relatively inexpensive material, such as an iron-based material, can be welded to the bolt shank 10 of a new bolt as shown in FIG.
In either case, the bolt has the shape of a hitherto known bolt having a bolt shank and a detachable shank, and the detachable shank is conventionally discarded, or the detachable shank is made of a relatively cheap material such as mild steel. An assembly is provided that can be used.

FIGS. 2 and 3 show an embodiment of the stud welding method according to the present invention. In this embodiment, the welding surface 17 of the shaft portion to be separated is formed in the shape of a truncated cone. The sloping section of the frustoconical welding surface begins at the outer peripheral section 18 of the shank to be cut off and ends at a flat section 19. Protruding welding tip 20
is located in the center of the flat portion 19 and serves to generate an arc in a manner conventionally known in capacitor discharge stud welding.

Furthermore, according to the invention, the shaft portion 21 extending beyond the fracture neck 13 is provided with a welding surface 22 having a complementary shape to the truncated conical welding surface 17 of the shaft section to be separated.

Welding surface 1 of the shaft part and bolt shaft part to be separated
7 and 22 respectively result in a larger area of weld contact area than if the weld surfaces extend perpendicularly or transversely to the axial direction of the bolt. As a result, when two bolts are welded together using capacitor discharge stud welding, the total area of a good weld between the two parts is the same as the cross-section of the two parts, even if blowholes, cavities, and contamination occur. It will be more than the area. In this way, it is possible to maintain the shape of the outer periphery of the bolt itself and perform welding with a welding strength higher than the actual cross-sectional strength of the bolt itself.

FIG. 4 shows a partial cross-sectional view of the hack-shaped tightening member in which the separated shaft portion 14 is re-welded.

As a non-limiting example, a diameter of 0.597
In the embodiment of the truncated conical welding surface of cm, the inclination angle of the truncated conical welding surface is 45°C, the width of the flat section 19 is kept approximately 0.18 cm, and therefore the height of the truncated conical welding surface is It is approximately 0.18cm. The protruding welding tip has a substantially truncated conical shape with a base of approximately 0.10 cm and a top of approximately 0.03 cm.

In the welding process, the voltage is preferably 100-130V, and the capacitance of the capacitor is preferably 80,000-100,000 μF. It is also preferred to use mineral oil in the arc generation area to stabilize the arc.

A hack-shaped clamping member of the dimensions described above made of titanium material with a welded shaft portion separated according to the present invention has been found to have a weld strength capable of withstanding a tensile load of approximately 2721.6 kg. Further, the tensile load at the fracture neck where the separated shaft portion breaks from the fracture neck of the bolt shaft portion is 2222.6Kg to 2404.1Kg.

As explained above, in this invention, the shape of the welded part is complementary to the shape of the two members to be welded together, and the welding strength of the two members is greater than the strength of the members themselves. can be welded.

The invention is not limited to welding elongated members together and their assembly, but has application in any case where it is desirable to increase the strength of the weld without increasing the external dimensions of the weld area of the members to be welded together. can.

[Brief explanation of drawings]

Figure 1 is a perspective view showing the hack-shaped tightening member with the part to be cut off welded to the newly formed bolt shaft, and Figure 2 is the hatch-shaped tightening member shown in Figure 1 before the part to be cut off is welded to the bolt shaft. FIG. 3 is a perspective view showing the member, FIG. 3 is a partial cross-sectional view showing a part of the hack-shaped tightening member shown in FIG. 2 before welding and a part of the shaft portion to be separated, and FIG. FIG. 3 is a partially sectional front view showing a welded portion between a bolt shaft portion of a hack-shaped tightening member that is welded together and a shaft portion that is to be separated; In the figure, 10: bolt shaft, 11: bolt head,
13: Broken neck, 14: Shaft to be separated, 1
6: Welding part, 17, 22: Welding surface, 20: Welding tip.

Claims (1)

[Scope of Claims] 1. An elongated tightening member body with a truncated conical welding surface larger than the cross-sectional area at one end, and made of a material cheaper than the tightening member body, and approximately equal to the welding surface of one end of the tightening member body. It consists of an elongated auxiliary member that has a complementary truncated conical welding surface at one end and is separated during use, and the welding surfaces of the tightening member main body and the auxiliary member are stud-welded on the same axis, and the A round bar-shaped tightening member characterized in that stud welds between the stud welds have approximately the same outline as those of the studs and have a welding strength equal to or greater than the strength of the studs themselves. 2 A truncated conical welding surface that is wider than the cross-sectional area is formed at one end of the elongated tightening member body, and has the same external dimensions as the elongated tightening member main body, and is attached to one end of the elongated tightening member main body at one end of the elongated auxiliary member that is separated during use. Manufacture of a round bar-shaped tightening member characterized by forming a truncated conical welding surface substantially complementary to the welding surface, and welding the welding surfaces of the tightening member main body and auxiliary member to each other on the same axis by stud welding. Method.