JPS5976640A - Working method of upset bolt having under filled head - Google Patents

Abstract

PURPOSE:To form exactly the vertical angle part of a hexagonal shape and to rationalize forging by forging the pyramidal face to be formed to the head of a hexagon headed bolt in such a way as to have a curved face of a projection type which is bulged into an under-filled part. CONSTITUTION:The under fill in the head of a hexagonal headed bolt B is formed to a hexagonal shape M1 in which the part near the inlet in an under fill part J is similar to a hexagonal shape M0 delineating the outside circumference of the head of the bolt B. The base T in the part J is formed to a hexagonal shape M2 having the similar shape smaller than the shape M1 above the part J. The respective pyramidal faces K-K to be formed between the lower part of the shape M1 and the shape M2 are so formed as to have the curved face m of a projection type bulged into the part J. A forging force is then concentrated at the part of each ridgeline Rn in the inverted pyramidal face part, whereby the vertical angle part of the hexagonal shape M0 on the outside is exactly formed and the forging of the lightweight bolt is considerably rationalized.

Description

[Detailed Description of the Invention] The method of the present invention relates to a method for processing an upset bolt having a thinning head, and its purpose is to forge a thinning part in the head in order to make the hex bolt lighter. −
・To invent a new shape for the thinned part that can reliably extrude the hexagonal shape 2, and to provide a processing method for the thinned part shape that has not yet been adopted in conventional hexagonal bolts of this type. It is to be. The gist of the method of the present invention is that the thinned state of the hexagonal bolt head is formed into a hexagonal M1 similar to the hexagonal Ml forming the outer periphery of the head of the hexagonal bolt B near the entrance of the thinned portion J; The bottom surface T of the thinned part J is formed into a similar hexagon M2 smaller than the hexagon M1 above the thinned part J, and each pyramidal surface formed between the lower part of the hexagon M1 and the hexagon M2. It is characterized by being forged to form a convex curved surface m that bulges into the thinned part J.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed explanation will be given with reference to the drawings showing one implementation method embodying the technical idea of the present invention.

In the drawing, the hexagonal pole I-B is formed as a main body consisting of a head H and a screw shaft S extending from the bottom surface of the head H.

The area around the entrance of the removed part J is formed into a polygon M1 similar to the hexagon MQ forming the outer periphery of the hexagonal part E, and the bottom surface T of the removed part J is similar to the hexagon M1 above the removed part J. It is formed into a small similar hexagon M2.

Each pyramidal surface formed below the hexagon M1 and between the hexagon M2 is formed so that -K becomes a convex W-curved surface m that bulges into the thinned portion J.

As shown in FIG. 1, the upper die U has a punched part U1 projecting from its lower end which becomes a male die when the above-mentioned thinned part J is made into a female die.

Next, a method for forging the thinned portion J of the above-described embodiment will be specifically explained.

Now, when the head H of the hexagonal pole (B) is forged using the above-mentioned upper 5U, a thinned part J is formed on the head H.

At this time, each pyramidal surface XX, which is silvered in the inverted pyramidal part of the bottom T of the thinned part J, becomes a convex curved surface m that bulges into the thinned part J. As a result, in FIG. 7, which shows enlarged cross-sectional views at three cross-sectional positions a to 0 shown in FIG. The apex portion of the square MQ must be formed accurately, which is also a particular advantage of the particular method of the invention.

That is, in the method of the present invention, the thinned state of the head of the hexagonal bolt is formed into a hexagonal M1 similar to the hexagonal MQ forming the outer periphery of the head of the hexagonal hole B near the entrance of the thinned part J; The bottom surface T of the portion J is formed into a similar hexagon M2 smaller than the hexagon M1 above the thinned portion J, and the hexagon M2 is smaller than the hexagon M1 above the thinned portion J.
Each pyramidal surface formed between the lower part of 1 and the hexagon M2 is forged so that it becomes a convex curved surface m that bulges into the thinned part J. In FIG. 7, which shows enlarged cross-sectional views at the six cross-sectional positions a-o shown in the figure, which are shown in the same center, the forging force is concentrated at each ridge line Rn of the inverted pyramidal surface, and the apex portion of the outer hexagon MQ is The method of the present invention can be said to be an extremely preferable invention as a method for processing upset bolts having a thinning head, since the bolts can be formed accurately and the forging process of lightweight bolts can be extremely streamlined.

In the figure, it is desirable that each corner be rounded, the ridge line Rn replaced with the sharp edge shown, and slightly brighter.

Furthermore, instead of the straight line shown in the drawing, the ridge line Rn may be made into a convex curve that slightly bulges inward, or a concave curve that bulges slightly outward. (Indicated by dotted lines in FIG. 4.)

Next, we will create a hexagonal pol) 2B with the above-mentioned ridge line made into a convex curve.
As an additional note, in FIGS. 8 to 10, the hexagonal pole 2B is mainly formed of a head 2H and a spiral portion S continuing to the lower surface of this l\rad H. The area near the entrance of the thinned part 2J is a hexagonal hole 2M forming the outer periphery of the hexagonal hole 2B.
It is formed into a polygon 2) 11 similar to O, and this thinned part 2
The bottom surface 2T of J is formed into a similar hexagon 2M2 smaller than the hexagon 2M1 above the thinned portion 2J. Each pyramidal surface 2 formed below the hexagon 2M1 and between the hexagon M2
2K is formed so that one convex curved surface m is carved out in the thinned part J.

As shown in FIGS. 8 and 9, the upper die U has a stamped part 2U1 which is a male die when the above-described thinned part 2J is a female die, and is provided with a protruding part 2U1 at its lower end.

In addition, in the figure, the lower part of the bottom surface 2T may be a recessed portion indicated by a dotted line 2D.

Now, attach the hexagonal bolt 2B at the upper F2U shown in Figures 8 and 9.
When is press-formed, the ridgeline 2Rn of the hexagonal portion at the bottom is formed into a convex curve. However, since its effect is almost the same as that of the previous example, hexagonal pol) B, its explanation will be omitted.

Furthermore, the technical idea of the method of this invention can be applied to heads of square bolts, which is very convenient.

[Brief explanation of drawings]

The drawings show each embodiment of the present invention, and FIG. 1 is a front view of the upper mold, FIG. 2 is a side sectional view thereof, FIG. 6 is a view taken in the direction of arrow P in FIG. 1, and FIG. 4 is a hexagonal view. 5 is a partially cutaway front view of the bolt, FIG. 5 is a sectional view taken along the line A-A in FIG. 4, FIG. 6 is a plan view of the hexagonal bolt, and FIG. C-
It is a cross-sectional explanatory view in which the C@ plane is marked tljt on the same center. 8 to 10 show the other side; FIG. 8 is a front view of the upper die, FIG. 9 is a side sectional view thereof, and FIG. 10 is a partially cutaway front view of the hexagonal bolt. B...Hexagonal B) v) MO, Ml, M2...Hexagonal K...Pyramid M...Convex curved surface J...Exclusion factor T...Bottom light, 2
Rn...Ridge line 2B...Hexagonal bolt Applicant: Katsuyo Nonoyama, Attorney: Hidehiko Okada, Figure 1, Figure 3, Figure 2

Claims (1)

[Claims] The thinned state of the head of the hexagonal po/I/) is formed into a hexagon M1 similar to the hexagon MQ forming the outer periphery of the head of the hexagonal po The bottom surface T is a similar hexagon M2 smaller than the hexagon M1 above the thinned part J.
and the lower part of the hexagon M1 and the hexagon M
Processing of an upset bolt having a thinning head characterized in that each pyramidal surface formed at 2f'lj is forged to form a convex curved surface bulging into the thinning part J. Method.