JP2768091B2 - Rolling dies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling die, and more particularly to a rolling die for forming an annular sunk portion on a shaft-like member having a flange portion.

[0002]

2. Description of the Related Art In a shaft-like member having a flange portion and a shaft portion extending at right angles from an end surface of the flange portion, an annular sunk portion is formed at an end portion of the shaft portion adjacent to the flange portion. May be needed. An example is a connecting rod bolt that fixes a rod and a cap that constitute a connecting rod. The connecting rod bolt includes a head portion as a flange portion, a shaft portion extending from an end face of the head portion, and a screw portion formed at a protruding end portion of the shaft portion. It is necessary to increase the area of the end face to be formed and reduce the surface pressure. Therefore, it is possible to form an annular indentation at the end adjacent to the head of the shaft so as to avoid the rounded portion at the end adjacent to the head of the shaft from reducing the seating area of the end face of the head. Is being done.

The formation of an annular groove in a shaft by a rolling die is known from Japanese Patent Application Laid-Open No. 59-87942. However, this rolling die is for forming an annular groove in a shaft-shaped member without a flange portion, and an annular sunk portion is formed at an end of the shaft-shaped member having a flange portion adjacent to the flange portion of the shaft portion. If you try to form
The material that escapes in the axial direction due to the bite of the protrusion formed on the rolling die enters between the protrusion and the flange, and the flange is deformed in a direction away from the shaft toward its outer peripheral side, and the flange and the shaft are deformed. The perpendicularity to the part becomes worse, and it cannot be used. Therefore, conventionally, in the case of forming an annular sunk portion at an end portion of a shaft-like member having a flange portion adjacent to the flange portion of the shaft portion, cutting has been performed.

[0004]

However, the cutting process is time-consuming, the productivity is low, the tool cost is high, and the cut formed by the process reduces the fatigue strength of the shaft-like member, and the durability is low. There was a low problem. An object of the present invention is to provide a rolling die capable of forming an annular sunk portion on a shaft-shaped member having a flange portion without impairing the perpendicularity between the flange portion and the shaft portion. It is.

[0005]

The rolling die according to the present invention comprises:
In order to solve the above-mentioned problem, a projection is formed on a surface of the main body portion facing the shaft portion of the shaft member to protrude toward the shaft portion side to form a sunk portion. A relief groove substantially formed along the projection is formed on the surface on the opposite side, and the depth of the relief groove is gradually reduced to zero at the terminal end.

[0006]

In the rolling die configured as described above,
When the protruding portion cuts into the shaft portion to form a dull portion, the material escapes to the escape groove, and a bulge protruding toward the rolling die is formed on the end face of the flange portion. Since the material that escapes to the flange portion due to the bite of the protrusion is stored in the escape groove, the material that escapes to the flange portion moves the flange portion away from the shaft portion as if there was no escape groove. The bent portion is formed while maintaining a right angle between the flange portion and the shaft portion without being bent. The bulge formed on the end face of the flange portion relatively moves from the base end to the front end of the projection as the flange rotates, and is squeezed by the projection. Therefore, the portion of the flange end surface that has passed through the protrusion has almost no swelling, but the portion before passing through the protrusion remains. This remaining bulge is gradually extinguished at the end of the relief groove whose depth is gradually reduced to zero. At this time, the formation of the bulge has already been almost completed, and the material hardly escapes, so no new bulge is formed.
As the clearance groove becomes shallower, the bulge remaining on the end surface of the flange portion is gradually lowered, and a slack portion is formed without impairing the perpendicularity of the end surface to the shaft portion.

[0007]

As described above, according to the rolling die of the present invention, the end of the shaft member adjacent to the flange portion of the shaft portion is formed without impairing the perpendicularity between the flange portion and the shaft portion. As a result, a sunk portion can be formed, and productivity can be improved. Further, the surface roughness of the sunk portion can be made extremely small, and the fatigue strength and the static strength can be improved as compared with the case where the sunk portion is formed by cutting. Forming the pit portion by rolling does not cause generation of cuts or cutting of the metal flow, and also improves strength by work hardening, so that a shaft-like member having excellent durability can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a rolling die for forming a slack portion on a shaft portion of a connecting rod bolt will be described in detail with reference to the drawings. In FIG. 6, reference numeral 10 denotes a connecting rod bolt. The connecting rod bolt 10 is formed at a head portion 12 as a disk-shaped flange portion, a shaft portion 16 extending perpendicularly from an end surface 14 of the head portion 12, and a tip portion of the shaft portion 16. And an external thread portion 18,
An annular recess 20 is formed at the end of the shaft 16 adjacent to the head 12.

[0009] The male thread portion 18 and the slack portion 20 of the connecting rod bolt 10 are formed by a rolling machine. The rolling plate has a first movable plate 22 and a second movable plate 24 that are provided so as to be movable in directions parallel to each other (a direction perpendicular to the paper surface) and in opposite directions. Between the first movable platen 22 and the second movable platen 24, positioning members 26 and 28 for positioning the material are provided facing each other, and one of the positioning members 28 is attached upward by a spring 30. The material is pressed against the positioning member 26.

The flat surfaces 34 of the first movable plate 22 and the second movable plate 24 facing each other are respectively provided with flat dies 34 for forming sneak portions.
And the screw forming flat die 36 are fixed in parallel with each other. On the surfaces of the flat dies 36 for screw formation facing each other,
The material is provided with a thread forming portion 38 for forming the male screw portion 18.

Each of the body portions 40 of the pair of flat dies 34 for forming a squeezed portion has a rectangular block shape in cross section. Are formed. As shown in FIG. 2, the flat dies 34 are arranged in order from the bite side.
A processing portion 44, a finishing portion 46, and a relief portion 48 are provided.
The processing portion 44 is inclined in such a direction as to move closer to the shaft portion 16 in the moving direction of the flat die 34 as the distance from the biting side increases, the finishing portion 46 is formed in parallel with the moving direction of the flat die 34, and the relief portion 48 is formed. In the moving direction, it is inclined in a direction away from the shaft portion 16 toward the escape side.

An escape groove 52 is formed along the protrusion 42 on the surface of the protrusion 42 facing the end surface 14 of the head 12. As shown in FIG.
In the processed portion 44, as shown in FIG.
_{It is} inclined by _one , and the depth is constant in the moving direction of the flat die 34. The inclination angle of the clearance groove 52 is gradually reduced in the finishing portion 46, and as shown in FIG. At the end, the depth and width are zero as shown in FIG. In the finished portion 46, the cross-sectional shape of the relief groove 52 is exaggerated toward the end in FIG.

On the other hand, the surface of the projection 42 on the side facing the shaft 16 is inclined at an angle θ ₂ away from the shaft 16 as shown in FIG.

The male thread 18 of the connecting rod bolt 10 and the recess 20 are formed by the rolling machine constructed as described above.
Is formed, after positioning the material on which the head 12 and the shaft 16 are formed by the positioning members 26 and 28, the first and second movable plates 22 and 24 are moved in opposite directions to each other, and The flat dies 34 for forming a portion and the flat dies 36 for forming a screw are cut into portions where the shaft portion 16 and the male screw portion 18 are formed, respectively.
The slack portion 20 and the male screw portion 18 are formed by the movement and rotation of the material.

As shown in FIG. 9, the material 5 is placed on both sides of the projection 42 in the axial direction of the shaft 16 due to the bite of the projection 42.
The material 56 that has escaped to the head 12 side enters the escape groove 52. The material 56 escaping into the escape groove 52
As the material rotates, it rotates as shown by the arrow A in FIG. 7, so that it is substantially equivalent to moving to the right in FIG. Disappear. While being processed by the processing unit 44,
When the material escapes into the escape groove 52, the material is squeezed by the protrusion 42.

As described above, the material escapes due to the bite of the protrusion 42, but the material 56 which escapes to the head 12 enters the escape groove 52 and projects from the end surface 14 of the head 12 toward the protrusion 42. Therefore, unlike the case where the escape groove 52 is not provided, the material that escapes toward the head 12 does not bend the head 12 away from the shaft 14, and the perpendicularity between the head 12 and the shaft 16 is reduced. The relief portion 20 is formed while maintaining.

As described above, since the bulge of the material 56 is squeezed by the vicinity of the tip of the protrusion 42 as the material rotates, the portion of the end surface 14 of the head 12 that passes through the vicinity of the tip of the protrusion 42 is flat. However, the bulge of the material 56 remains in the portion before passing through the vicinity of the tip end as shown by the broken line in FIG.

The bulge of the material 56 is extinguished at the end where the depth and width of the clearance groove 52 are gradually reduced. At the end of the escape groove 52, as shown in FIG. 5, the inclination angle θ ₁ is gradually reduced, and the side edge 54 on the side closer to the tip of the protrusion 42 gradually moves away from the tip. As shown in (a), (b), and (c), the bulge of the material 56 is crushed while being squeezed outward in the radial direction of the end face 14, and finally disappears.

As described above, the depth and width of the clearance groove 52 are gradually reduced to zero at the terminal end side, but in the finished portion 46 where the terminal end of the clearance groove 52 is formed, the formation of the slack portion 20 has already been performed. Is almost finished, and new material hardly escapes. Therefore, even if the depth of the escape groove 52 is gradually reduced to zero, the head 12 does not bend. At the end of the clearance groove 52, the bulge generated at the time of processing by the processing portion 44 and remaining on the end face 14 of the head 12 becomes gradually shallow, and the bottom surface of the clearance groove 52 whose width becomes narrower radially outwards. The end surface 14 is a flat surface with good flatness.

FIGS. 9 and 10 show how the material escapes when the slack portion 20 is formed by changing the inclination angle θ ₁ .
As is apparent from these figures, in the case of the projection 42 having a small inclination angle θ ₁ , the clearance groove 52 is positioned away from the center line O of the shaft 16.
The distance L ₁ from the end surface 14 of the material 56 that has escaped to the most protruding portion is longer than the distance L ₂ when the slack portion 20 is formed by the protrusion 42 having a large inclination angle θ ₁ ,
The smaller the inclination angle θ ₁ is, the more the material can be pushed to the portion of the end face 14 having a large radius.

The roundness R at the tip of the projection 42 should be determined in consideration of the amount of the protrusion 42 pressed into the material in the radial direction, and the like. Since the rotation resistance of the material is different, it is necessary to make the size such that the material does not slip and the material does not peel. If the rotation resistance is large, the material will not rotate due to slippage, or the material will peel off on the surface of the squeezed portion 20.

Experiments were conducted by changing the inclination angle θ ₁ of these clearance grooves 52 and the roundness R of the tip of the projection 42, and the results shown in FIG. 8 were obtained. As is clear from this figure, there is an appropriate range for the inclination angle θ ₁ and the roundness R in order to form the recessed portion 20 without causing peeling or slipping, and in the present embodiment, the inclination angle θ ₁ is 2. Five degrees, the roundness R is 0.8.

In this embodiment, the male thread 18 is formed at the same time as the slack 20. For this reason, the bite of the thread forming portion 38 into the material prevents the material from moving in the axial direction, so that the head portion 12 is satisfactorily pressed against the flat portion forming die 34, and the slack portion is formed by cutting. The deviation of the squareness is 2 compared to the case of forming
It can be reduced by a factor of one.

In the above embodiment, the finishing unit 4
In FIG. 6, the inclination angle and width of the escape groove 52 formed in the protrusion 42 are gradually reduced to zero, and the depth is gradually reduced to zero. However, as in the case of the escape groove 62 of the protrusion 60 shown in FIG. Alternatively, without changing the inclination angle, only the width may be gradually reduced to zero, and the depth may be gradually reduced to zero.
As in the escape groove 66 of the projection 64 shown in FIG.
Alternatively, only the inclination angle may be gradually reduced to zero, and the depth may be gradually reduced to zero.

In the above embodiment, the case where the present invention is applied to a flat die has been described as an example, but the present invention can also be applied to a round die.

In addition, without departing from the scope of the claims, the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

[Brief description of the drawings]

FIG. 1 is a front view showing a flat die for forming a slack portion according to an embodiment of the present invention.

FIG. 2 is a plan view showing the flat die for forming a sneak portion.

FIG. 3 is a sectional view taken along the line III-III in FIG.

FIG. 4 is a sectional view taken along line IV-IV in FIG.

FIG. 5 is a side cross-sectional view showing, on an enlarged scale, a projection of the flat die for forming a sneak portion.

FIG. 6 is a view schematically showing a rolling machine provided with the flat die for forming a sneak portion.

FIG. 7 is a view for explaining a state in which a bulge generated on the end face of the head of the material at the time of forming the slack portion by the protrusion is crushed by the vicinity of the tip of the protrusion.

FIG. 8 is a graph showing the occurrence of slipping and peeling of the material when the slack portion is formed by changing the rounded portion at the end of the flat die for forming the slack portion and the inclination angle of the escape groove.

FIG. 9 is a view showing a processing state in the case where the inclination angle of the escape groove of the flat die for forming a slush portion is small.

FIG. 10 is a view showing a processing state in the case where the inclination angle of the relief groove of the flat die for forming a slush portion is large.

FIG. 11 is a view for explaining a state in which a bulge generated on a head end face of a material disappears due to a change in the depth of a clearance groove when forming a sunk portion by the flat dies for forming a sunk portion.

FIG. 12 is a side view showing a protrusion of a flat die for forming a slack portion according to another embodiment of the present invention.

FIG. 13 is a side view showing a projection of a flat die for forming a recess portion according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Shaft-like member 12 Head 14 End face 16 Shaft 20 Sliding part 34 Flat die for forming slanting part 40 Main body part 42 Protrusion part 52 Relief groove 60 Protrusion part 62 Relief groove 64 Protrusion part 66 Relief groove

Continuation of the front page (56) References JP-A-52-144546 (JP, A) JP-A-1-104434 (JP, A) JP-A-59-87942 (JP, A) JP-B-59-22613 (JP, A) , B2) Japanese Patent Publication No. 1-52099 (JP, B2) Japanese Patent Publication No. 2-51692 (JP, B2) Japanese Patent Publication No. 51-34376 (JP, B2) Japanese Patent Publication No. 53-19466 (JP, B2) (58) Surveyed field (Int.Cl. ⁶ , DB name) B21H 1/00 B21H 3/06

Claims (1)

(57) [Claims] An axially extending member having a flange portion and a shaft portion extending at right angles from an end surface of the flange portion, the rolling member forming an annular sunk portion at an end portion adjacent to the flange portion of the shaft portion. In the forming die, a projection is formed on a surface of the main body portion facing the shaft portion so as to protrude toward the shaft portion to form the sunk portion, and along a surface of the main body portion facing the end surface substantially along the projection portion. A rolling die, wherein a relief groove is formed, and the depth of the relief groove is gradually reduced to zero at a terminal end.