JPH0237475Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a die for heading the head of a polygonal bolt, and in particular, it is designed to facilitate the removal of waste from processed materials and to improve durability. Regarding dice.

(Prior Art) Conventionally, when forging the head of a polygonal bolt, first a bolt material 1 is prepared as shown in a of FIG. 1, and then a schematic head 2 is forged as shown in b. ,
Finally, a flanged hexagonal bolt head 3 as shown in c is forged. Note that the tsuba 4 is not necessarily necessary.

In the final step shown in FIG. 1c, a heading die as shown in FIGS. 2 and 3 has conventionally been generally used.

This conventional heading die includes a cylindrical case 11 having a bush 10 inside as required;
A plurality of (for example, six) nib pieces 12 are fitted into, for example, hexagonal nib press-fit holes of the bush 10. Each nib piece 12 has a substantially trapezoidal cross section, has an inner surface 13 corresponding to one side of the head 3 (FIG. 1) of a hexagonal bolt, etc., and extends from both ends of the inner surface 13 and is pressed against the adjacent nib pieces 12. an outer surface 16 located between the ends of these tightening surfaces 14 and press-fitted into the inner wall surface 15 of the nib press-fit hole of the bushing 10 integrated into the case 11; It has

When heading is performed using this die, the head 2 (the first
(Fig.) and press-fit.

(Problem to be solved by the invention) However, in the case of this conventional die, the split nib (nib piece 12) is tightened by the impact during driving.
When the gap between the holes 4 and 4 opens, bonding powder, scale, oil, etc. on the surface of the bolt material between them will get in and the accumulated residue will gradually push the nib piece 12 wider, degrading the finishing accuracy and damaging the bush 10 or the case 11. There is a problem with it being damaged. Further, if debris or the like accumulates between the nib pieces 12 and is gradually spread out, it appears as burrs on the product. In addition, although there is a type in which each nib piece 12 is formed integrally, there is a drawback that the nib itself is easily broken in this case.

In order to prevent debris from accumulating between the nib pieces 12 as described above, conventionally, notches are formed at both ends of the outer surface 16 of each nib piece 12, and each nib piece 12 and the bush 10 or case 11 are press-fitted into the runnibs. Hole inner wall surface 15
A recess 1 for accommodating debris and relieving stress between the
It has also been proposed to provide 8.

In this case, in order to avoid problems caused by scale, etc., it is necessary to take out the material accumulated in the recess 18 upward each time, and the removal work is extremely complicated, and the area of the outer surface 16 of each nib piece 12 As a result, a large pressure is locally applied to the bush 10 or the case 11 during forging, which increases the load and tends to deteriorate overall durability.

(Means for Solving the Problems) The present invention has been made based on such conventional problems. In addition to forming a concave part for discharging scraps, it also communicates with the scrap discharge hole via a passage, which avoids the accumulation of scraps from the material, and improves overall durability by eliminating localized excessive pressure. This is a heading die.

(Example) The present invention will be described below with reference to an example shown in FIGS. 4 to 6.

In these figures, the heading die of this embodiment includes a substantially cylindrical case 21, a cylindrical bush 20 inserted inside the case 21, and a case 21 located on the bottom side of the bush 20. a disc-shaped spacer 29 inserted inside the nib press-fit hole 22 formed by the bush 20 and the inner surface of the spacer 29;
A plurality of (six pieces in this embodiment) nib pieces 23 are fitted into the nib pieces 23.

It is also possible to omit the bush 20 and spacer 29 and form the nib press-fit hole 22 directly inside the case 21.

Further, each of the nib pieces 23 is a square columnar member having a substantially trapezoidal cross section, and has an inner surface 24 corresponding to one side of the head of a polygonal bolt (hexagonal bolt), and extends from both ends of the inner surface 23. Adjacent nib piece 2
3, and an outer surface 27 located between the ends of these tightening surfaces 25 and pressed against the inner wall surface 26 of the nib press-fit hole 22. There is.

Further, according to the present invention, a waste discharge recess 28 is formed in at least one of the tightening assembly surfaces 25. This waste discharge recess 28 is located approximately at the center of the tightening assembly surface 25 along the radial direction
It extends over the entire length of 5. Further, the waste discharge recess 28 may be formed so as to face the waste discharge recess of another adjacent nib piece 23 in the nib press-fit hole 22. In this case, as shown in FIG. The concave portion 28 may be formed symmetrically with respect to the boundary line of the nib piece 23, but is not limited thereto, and may have any asymmetric shape.

Next, the spacer 29 inserted into the bottom side of the bush 20 in the case 21
A plurality of radial grooves 31 are formed on the upper surface of the spacer 29 to support each nib piece 23, and extend radially in the radial direction and communicate with the waste discharge recess 28, and each of these radial grooves. An annular groove 32 is formed to allow the radial grooves 31 to communicate with each other, and the radial groove 31 and the annular groove 32 form a discharge passage. Further, the case 21 is provided with a waste discharge hole 33, one of which opens toward the bottom of the nib press-fit hole 22 and communicates with the annular groove 32, and the other opens to the outside of the case 21.

The discharge passage may be provided on the bottom surface of the nib piece 23, or may be provided directly within the case 21 if the spacer 29 is omitted.

The above-described forging die according to the present invention is installed in a bolt cold heading machine in a horizontally opposed manner to a mating die on which a bolt material whose tip is roughly pressed is mounted, and works in cooperation with the mating die. As shown in FIGS. 7 and 8, it is used as a finishing second forming punch for forming a polygonal (for example, hexagonal) head.

In other words, the first
A bolt material 1 whose head has been pre-formed into a roughly pressed head 2 as shown in FIG. A knockout pin 36 is inserted into the side die 34 and die nib 35 from the rear end side so as to be able to push out the bolt material 1.

The forging die of the present invention also includes a punch insert 37 having a punch 37a formed at its tip for making a recess in the upper surface of the bolt head with a polygonal column (for example, a hexagonal column) that can fit into the press-fit hole 30. is inserted from the rear end side of the case 21, and the punch insert 37 is supported by an insert die 38, which is also inserted from the rear end side of the case 21, so as to be movable forward and backward.

Then, from the state shown in FIG. 7, the forging die of the present invention and the insert die 38 are moved by a driving device (not shown) to the mating die 34 and the die nib 35.
As a result, the roughly pressed head 2 is loosely fitted into the press-fit hole 30 formed by each nib piece 23 in the nib press-fit hole 22 . Next, the insert die 38 is further advanced to form the punch insert 37.
When inserted into the press-fit hole 30 as shown in Fig. 8,
The roughly pressed head 2 pressed by the punch insert 37 is pressed into a polygonal (for example, hexagonal) head 3 by the regulation of the press-fit hole 30.

After that, first, only the heading die of the present invention is slightly retreated to allow the head 3 to escape from the press-fit hole 30, and then the heading die of the present invention and the insert die 38 are simultaneously retreated to a predetermined position. Then, the knockout pin 36 is advanced to eject the bolt material 1 inside the die nib 35. still,
The ejected bolt material 1 is dropped onto a pedestal (not shown) disposed below, and a thread is rolled into the bolt material 1 in the next step.

Note that the forging dies of the present invention according to this embodiment are examples for forging a hexagonal head without a flange, and for forging a head with a flange as shown in Fig. As is conventional practice, the press-fit hole 30 is provided with a tapered portion on its inner surface to fit a flange.
Further, in FIG. 6, the draft taper formed on the inner surface of the press-fit hole 30 is exaggerated, and the press-fit hole 30 is an example of a case where a hexagonal head without a flange is forged.

In this case, the scraps of the bolt material etc. are removed from the nib piece 23.
Recessed portion 2 for waste discharge formed in the tightening assembly surface 25 of
The radial groove 31 that collects in the discharge passage 8 and constitutes the discharge passage.
and is gradually pushed out of the case 21 through the annular groove 32 and the waste discharge hole 33. Therefore, the waste etc. are automatically discharged, making the removal work easy, and the space between the clamping assembly surfaces 25 of each nib piece 23 is not pushed apart by the waste etc., thereby preventing burrs, scratches, etc. on the product. There is no problem causing this. Further, there is no problem that the bush 21 or the case 20 may be broken due to debris or the like pushing the nib piece 23 apart.

Furthermore, in the present invention, the waste discharge recess 2
8 is provided at approximately the center of the tightening assembly surface 25 of the nib piece 23, the area of the outer surface 27 of the nib piece 23 is not reduced as in the conventional case, and therefore, the bush 20 is removed from each nib piece 23 during forging. In addition, excessive pressure is not applied locally to the case 21 or the bush 20 or the case 21.
This further reduces the risk of damaging the Therefore, the overall durability is further improved.

(Effects of the invention) As explained above, according to the invention, it is possible to easily remove material debris, improve the finishing accuracy of the product, and prevent excessive pressure locally in the nib press-fit hole. It is possible to obtain a die for heading the head of a polygonal bolt, which can improve overall durability without stress.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the head forging process of a polygonal bolt, Fig. 2 is a front view of a conventional heading die,
3 is a sectional view taken along the line -- in FIG. 2, FIG. 4 is a front view of a heading die according to an embodiment of the present invention, and FIG. 5 is a perspective view of a nib piece in the die shown in FIG. 4. 6th
The figure is a sectional view taken along the line -- in FIG. 4, and FIGS. 7 and 8 are longitudinal sectional views illustrating the usage state of the heading die of the present invention. Explanation of symbols, 1... Polygonal bolt material, 2...
Roughly pressed head, 3...head, 20...butsuyu, 2
DESCRIPTION OF SYMBOLS 1...Case, 22...Nib press-fit hole, 23...Nib piece, 24...Inner surface, 25...Tightening assembly surface, 26...
...inner wall surface, 27 ... outer surface, 28 ... recess for waste discharge, 29 ... spacer, 30 ... press-fit hole, 31 ...
...Discharge passage, 32...Annular groove, 33...Scrap discharge hole, 34...(Mating side) die, 35...Die nib, 36...Knockout pin, 37...Punch insert, 38...Insert die .

Claims (1)

[Claims for Utility Model Registration] Comprising a plurality of nib pieces that are substantially fitted into the nib press-fit hole of the case, each nib piece has an inner surface corresponding to one side of the head of the polygonal bolt, and an inner surface of the inner surface. two clamping surfaces extending from both ends and pressed against adjacent nib pieces, and an outer surface located between the ends of these clamping surfaces and pressed against the inner wall surface of the nib press-fitting hole of the case. A polygonal bolt head forging die having a die for forming a head of a polygonal bolt, wherein at least one of the tightening surfaces of the nib piece is located approximately at the center of the tightening surface along the radial direction of the case. A scum discharge recess is formed extending along the entire length of the fastening assembly surface along the axial direction of the case, and a nib press-fitting hole of the case has a recess at the bottom into which these nib pieces are substantially inserted. A spacer is fitted and each nib piece is placed on top of the spacer, and the case is provided with a waste discharge hole, one of which opens toward the bottom of the nib press-fit hole and the other opens toward the side of the case. The upper surface side of the spacer has radial grooves that extend along the tightening surface of each nib piece and communicate with the bottom of the waste discharge recess, and a groove that communicates with the radial grooves and connects to the waste discharge hole. A discharge passage consisting of an annular groove along the outer periphery of the nib press-fitting hole is provided in a communicating manner, and the scraps accommodated in the scrap discharge recess are sequentially discharged to the outside of the case via the discharge passage and the scrap discharge hole. A die for heading a polygonal bolt head, which is characterized by the following: