JPS5922609B2 - Molding method of boss with tightening bolt - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of forming a boss with a tightening bolt.

In the case of a boss with a tightening bolt, in which a slit is provided in the gripping part that clamps the shaft, a bolt is installed between the slits, and the shaft is fixed by tightening the bolt, in order to screw the bolt into the boss, Cut a thread around the inside of the bolt hole.

For this reason, the portion in which the screw hole is to be drilled must have a certain degree of thickness. In order to make the part where the screw hole is inserted thicker, conventionally the boss was forged and this part was made thicker. However, when the boss is made of forged material, the gripping portion that clamps the shaft must be bored after forging, which results in wasted material, and has the drawback of being time-consuming and expensive to manufacture. When manufacturing by pressing a plate material, there is a method in which both outer ends of the boss are bent inward to form a double structure, bolt holes are provided here, and threads are cut on the inner periphery.

However, this method touches on other companies' patents and cannot be implemented without permission. Therefore, the present invention is a method for forming a boss with a tightening bolt, which has been proposed in consideration of the above circumstances. I will explain based on this.

Fig. 1 is a perspective view showing how the boss A with tightening bolt is used;
2 to 6 are explanatory diagrams showing the molding process of the boss A.

First, a plate material is pressed to form a rectangular blank 2 having arc-shaped protrusions on both left and right sides of the upper end (these will be the parts where screw holes for tightening bolts to be described later will be provided).

Next, the blank 2 is crushed and molded to make the central part 4 thinner, excluding the protruding part 1 and the left and right edges 3, 3 following this, and the slope 5 connecting the protruding part 1 and the central part 4 to have an arcuate cross section. to curve. When the radius of curvature of this curved surface is made to match the radius of curvature of the gripping part 6, which will be explained next, when the bending process is performed,
As it is, it should be connected smoothly to the grip part 6.
In this crushing process, the mold is designed so that the protruding portion 1 maintains the original thickness of the plate material, the central portion 4 becomes thinner, and the material spreads from side to side. Next, using a press bending die, the plank 2 is bent from the left and right sides to form a cylindrical gripping part 6 that clamps the shaft at the center part 4, and a slit T is provided on the upper surface of the gripping part 6. Furthermore, a separately molded mounting flange 8 is welded to the lower end. Bolt holes 9, 9 for fixing are provided on both the left and right sides of the flange 8. Finally, screw holes 11 and holes 111 for the tightening bolts 10 are bored in the left and right protrusions 1, 1, and a notch 12 for preventing rotation is provided on the inner periphery of the discharging part 6. In order to use the boss A molded as described above as a shaft joint for a steering shaft, as shown in FIG.
After fixing the shafts 15, 15 with the mounting bolts 14, 14 so as to be perpendicular to each other, the shafts 15, 15 are respectively inserted into the grip portion 6, and the tightening bolts 10 are tightened to fix the shafts 15, 15.

As explained above, in the crushing process in which the protruding part of the plank is made thicker than the gripping part, at the same time, the slope connecting the central part, which will become the gripping part, and the protruding part has an arcuate cross-section. The slope was molded so that the slope smoothly continued with the grip.

Therefore, all cutting work after molding is omitted, and the work is completed only by the pressing process, which greatly reduces production costs and saves materials.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing how the boss A with tightening bolt is used;
2 to 6 are explanatory diagrams showing the molding process of the boss A, and FIG. 1 is a partially cutaway front view. 1...Protrusion, 2...Blank, 3.
... Edge, 4 ... Center, 5 ...
・Slope, 6...Gripping part, 11...Screw hole.

Claims (1)

[Claims] 1. A punching process in which a plate material is punched out to form a rectangular blank with arc-shaped protrusions on both left and right ends of the upper end, and the central part excluding the protrusions and the edges following this is thinned, and the protrusions are A crushing process in which the slope connecting the central part of the blank is formed into an arcuate cross-sectional shape, a bending process in which the above-mentioned blank is bent from left and right using a press bending die to form a cylindrical gripping part at the center of the blank, A method for forming a boss with a tightening bolt, the method comprising the step of drilling a screw hole for a tightening bolt in a protruding portion of the boss.