JPH08243672A - Round form-rolling method - Google Patents

Abstract

PURPOSE: To form a clearance part by a round form-rolling at the high efficiency on the end part outer surface of a shaft part adjoined on the flange part of a shaft-like member without the difference of step in the flange part. CONSTITUTION: A projecting part 22a for forming the clearance part 12b is arranged on each outer surface of one pair of round dies 22 interposing the shaft part 12 of the shaft-like member 10. One side of the round die 22 is advanced/retreated to the shaft part 12, and the clearance part 12b is formed on the end part outer surface of the shaft part 12 with the projecting part 22a. During this formation, the shaft-like member 10 is shifted in the axial direction to the flange part 11 side. The projecting part 22a is separated from the flange part 11 during forming the clearance part 12b and the excess thickness developing accompanying the formation of the clearance part 12b is collected to the tip side of the shaft part on the reverse side to the flange part 11. It is avoided that the excess thickness is inserted between the flange part 11 and the round die 22, and the difference of step in the flange part is not caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a round rolling method for forming an annular recess on the outer surface of a shaft member having a flange.

[0002]

2. Description of the Related Art In a shaft-shaped member having a flange portion and a shaft portion extending at a right angle from the end surface of the flange portion, an annular recess is formed on the outer surface of the end portion of the shaft portion adjacent to the flange portion. There are cases. One example is a connecting rod bolt that connects a rod and a cap that form a connecting rod.

For example, as shown in FIG. 4, the connecting rod bolt has a head portion 11 which is a flange portion, a shaft portion 12 which extends at a right angle from a central portion of an end face of the head portion 11, and a tip portion of the shaft portion 12. And the formed male screw portion 13. Here, if roundness remains on the end outer surface 12a of the shaft portion 12 adjacent to the head portion 11, the seating area of the head portion 11 is limited when the head portion 11 is seated on the cap, and the surface per unit area is limited. The pressure increases. Therefore, a ring-shaped recess 12 called an under neck recess is formed on the outer surface 12a of the end of the shaft 12 adjacent to the head 11.
b is formed so that the seating area of the head portion 11 is not limited.

The under neck neck of such a connecting rod bolt can be processed by round rolling.

When forming the recessed portion 12b of the connecting rod bolt 10 and the male screw portion 13 at the same time by round rolling, as shown in FIG. 3, a pair of round dies 5, 5 for threading are formed.
5 and a pair of round dies 6, 6 for carrying out the dull work. The round dies 5, 6 on one side do not move in the direction perpendicular to the central axis, and the round dies 5, 6 on the other side
The round dies 5 and 6 on one side are driven back and forth. The pair of circular dies 5, 6 and 5, 6 are interlocked with each other by gears or belts so as to rotate synchronously.

In the processing, the shaft portion 12 is positioned between the fixed-side round dies 5 and 6 and the movable-side round dies 5 and 6, and the movable-side round dies 5 and 6 are rotated to be attached to the shaft portion 12. Move forward. The shaft 12 being processed is supported by the blade 7. Conventional round dies used for slimming 6,
The outer surface of the shaft 6 has a protrusion 6a that projects toward the outer surface 12a of the end of the shaft 12.

In the simultaneous formation of the recessed portion 12b and the male screw portion 13 by such round rolling, as shown in FIGS. 5 (A) and 5 (B), the protruding portion 6a bites into the outer surface 12a of the end portion of the shaft portion 12. As a result, the recessed portion 12b is formed. However, the excess thickness removed by the biting of the protrusion 6a escapes along the tip inclined surface of the protrusion 6a, and the excess thickness A on the head side and the excess thickness B on the non-head side occur. This head side surplus A
Is sandwiched between the head end surface 11a and the surface 6b of the protrusion 6a that faces the head end surface 11a. Therefore, as shown in FIG. 5C, the connecting rod bolt having the step C on the head end surface 11a is It is formed.

[0008]

In the case of machining a neck-necked recess of a shaft-shaped member having a flange portion such as a connecting rod bolt, the round rolling has a short cycle time and high efficiency. However, in the conventional round rolling, the extra thickness is sandwiched between the protrusion of the round die and the head end surface of the shaft-like member, and a bolt having a step C on the head end surface is formed.

When the connecting rod is fastened using such a connecting rod bolt having the step C, the excess thickness of the head end face 11a of the bolt is one of the seats of the rod or the cap constituting the connecting rod at the beginning of use. Although it is in contact with the surface, when the bolt is subsequently applied to the bolt by the connecting rod, the extra portion bites into the seat surface, and a gap is created between the rod and the cap or between the nut and the seat surface. It is not possible to use connecting rod bolts that can create such gaps.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to process an annular under neck recess in a shaft-shaped member having a flange portion by using a round die. By moving the shaft-shaped member in the axial direction toward the flange part, the excess thickness produced by the protrusion of the round die cutting into the shaft part of the shaft-shaped member is collected in the direction away from the flange part. It is an object of the present invention to provide a round rolling method capable of manufacturing a shaft-shaped member having a stepless underneck without a step by avoiding a phenomenon in which a surplus thickness is sandwiched between the shaft and the portion.

[0011]

The round rolling method of the present invention comprises:
A shaft-shaped member having a flange portion and a shaft portion extending at a right angle from an end surface of the flange portion, the shaft portion being sandwiched between a pair of shaft portion holding circular dies, and a pair of slush having an annular protrusion on the outer surface. An annular recess is formed on the outer surface of the end of the shaft portion adjacent to the flange portion of the shaft-shaped member by advancing one of the processing circular dies from the initial position toward the shaft-shaped member and retracting it again to the initial position. In the round rolling method, the protrusions of the pair of slushing round dies are brought into contact with the shaft portion of the shaft-shaped member, and then one of the slushing round dies is advanced toward the center of the shaft portion. At the same time, the shaft-shaped member is axially moved toward the flange portion to form an annular recess.

[0012]

In this round rolling method, first, one round die of the pair of sneaker round dies is advanced toward the shaft portion of the shaft-shaped member, and the protrusions formed on the pair of round dies. The tip is brought into contact with the shaft portion of the shaft member. Further, when one round die is advanced, each protrusion starts to bite into the outer surface of the end portion of the shaft portion adjacent to the flange portion of the shaft-shaped member, and starts forming an annular recess on the outer surface of the end portion.

At this time, at the same time when the round die bites into the shaft portion, the shaft-like member axially moves toward the flange portion side, and as a relative movement thereof, the protrusion separates from the flange portion. When the protrusion approaches the center of the shaft, the protrusion separates from the flange, so that the recessed portion formed on the outer surface of the end of the shaft becomes deeper as it separates from the flange.

Then, the movement of the shaft-shaped member is stopped and the projection separates from the center of the shaft, or the projection further separates from the flange when the projection separates from the center of the shaft, so that The recessed portion formed on the outer surface of the end portion becomes shallower as it goes away from the flange portion due to the curved shape of the protrusion itself or the processing by the protrusion.

In any of the processing steps, since the projection moves forward and moves relative to the flange at the same time, all the surplus material to be removed is on the inclined surface of the projection opposite to the flange. Occurs. The excess thickness is scraped by the relative movement of the protrusions to the side away from the flange portion, and finally discharged to the side opposite to the flange of the recessed portion formed on the outer surface of the shaft portion. Thus, the phenomenon that the extra thickness is sandwiched between the protruding portion and the flange portion is avoided, and the shaft-shaped member with a neck undercut by round rolling can be processed without causing a step.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the main part of an example of a round rolling device embodying the present invention, in which FIG.
FIG. 2B is a plan view, and FIG. 2 is an enlarged plan view of a working portion showing the state of the rolling work step by step.

In the present embodiment, as shown in FIG. 1, the present invention is applied to the processing of a connecting rod bolt 10 used for connecting a rod and a cap constituting a connecting rod. The connecting rod bolt 10 includes a head portion 11 that is a flange portion, a shaft portion 12 that extends at a right angle from the center portion of the head end surface 11 a, and a male screw portion 13 formed at the tip end portion of the shaft portion 12. , Shank 1 adjacent to head 11
The outer surface 12a of the second end has an annular recess 12b.

The round rolling apparatus of this embodiment forms simultaneously the thinned portion 12b and the male screw portion 13 of the connecting rod bolt 10, and for forming the round rolling machine, a pair of left and right round rolling machines 20 and 20 are arranged horizontally. To use. Round rolling machine 20, 20
Each of them comprises a round die 21 for screw processing and a round die 22 for dimming as a shaft holding circular die. The round die 21 for screw processing is a round rolling machine 20.
Round die 2 for one of the axial direction of the
2 is located on the other end side in the axial direction of the round rolling machine 20.

In FIG. 1A, one end side where the round die 21 for screw machining is located is the back side and the other end where the round die 22 for slimming is located is the front side. Then, one end side where the round die 21 is located is referred to as a back side, and the other end side where the round die 22 is located is referred to as a front side.

The rotary rolling machines 20, 20 on both sides are attached to a rotary shaft (not shown) (which is interlocked with a gear or a belt so as to rotate synchronously) with its central axis oriented in the horizontal direction, and they are mutually the same. Rotate synchronously in the direction. The round rolling machine 20 on one side (the left side in FIG. 1) is fixed in a direction perpendicular to the central axis. The circular rolling machine 20 on the other side (right side in FIG. 1) has its central axis passing through a horizontal plane L (shown by a chain line in FIG. 1) passing through central axes of the circular rolling machines 20, 20 on both sides. While moving in and out. Between the round rolling machines 20 and 20,
Blade 30 for supporting the shaft 12 of the rough material from below
Is provided. Further, a pusher 40 for pressing the head portion 11 of the rough material toward the tip side of the shaft portion 12 is provided.

The movable round die 21 for screw processing
The round die 22 and the rounded die 22 may be integrally rotated by one common rotary shaft and movable on the horizontal plane L, or two separate rotary shafts may be used to separate the round dies 21 and 22 from each other. Then, the structure may be rotatable and movable.

The rough material having the head portion 11 and the shaft portion 12 is placed on the blade 30 arranged between the round rolling machines 20, 20 with the head portion 11 facing the front side. Thus, the shaft portion 12 is arranged between the round rolling machines 20, 20 on both sides. After the rough material is set, the rough material is urged in the axial direction toward the tip side of the shaft portion 12 by the pusher 40 immediately before starting the rolling, so that the head end surface 11a of the rough material is rolled. The circular dies 22, 22 on the front side of the boards 20, 20 are elastically pressed.

The round dies 21 and 21 on the back side are for rolling the male screw portion 13 of the connecting rod bolt 10, and lead so as to axially move the rough material toward the head portion 11 during the rolling. Corner B _D is designed. That is, the die and the rough material mesh with each other during thread rolling, but the lead angle B _{D of the} meshing portion is the lead angle B of the product from the start of rolling to the end of rolling.
Round dies 21, 2 such that B _D <B _W with respect to _W
The lead angle B _{D of} 1 is designed.

Further, when the rolling dies rotate in the direction opposite to that shown on the round rolling machines 20, 20, the lead angles B _D of the round dies 21, 21 are set so that B _D > B _W. As a result, the same effect as described above can be obtained.

Therefore, in this embodiment, the round dies 21 and 21 for screw processing also serve as the driving mechanism 50 for axially moving the shaft-shaped member toward the flange portion.

The round dies 22, 22 on the front side are for rolling the recessed portion 12b on the outer surface 12a of the end portion of the shaft portion 12 adjacent to the head portion 11 of the connecting rod bolt 10. On the outer surface of each end on the side
an annular protrusion 22a protruding toward the outer peripheral side so as to face a,
22a. The protrusions 22a, 22a are inclined to the front side in order to form a gap G between the front end surfaces of the round dies 22, 22 and the rough head end surface 11a facing the end surfaces.

With the round rolling device configured as described above, the recessed portion 12b of the connecting rod bolt 10 and the male screw portion 1 are formed.
3 is formed, the movable side round rolling machine 20 is retracted to the initial position apart from the fixed side round rolling machine 20, and a rough material is placed on the blade 30 in the same direction. The shaft portion 12 made of a coarse material is arranged between the round rolling machines 20, 20 which rotate on both sides. Then, before advancing the movable round rolling machine 20, the pusher 40 is operated to urge the rough material in the axial direction toward the tip end side of the shaft portion 12.

The biasing of the rough material toward the tip side of the shaft portion 12 with the pusher 40 is performed so that the projection 22a does not separate from the head end surface 11a, and the end outer surface 12a is as close as possible to the head end surface 11a. This is for performing a slimming process.

From the time when the movable round rolling machine 20 moves forward while rotating, and the projection 22a of the round die 22 comes into contact with the outer surface 12a of the end of the shaft 12 adjacent to the projection 22a of the rough material,
The rolling process of the dull skin shown in FIG. 2 begins.

In this rolling process, the projection 22a is formed on the shaft 12
The amount of cut of the projection 22a with respect to the outer surface 12a of the end portion increases as it approaches the center of the, but the rolling process of the male screw by the round die 21 also starts at the same time as the rolling process of the slime begins. With the rough material, pusher 40
It moves axially toward the pusher 40 side against the axial urging force of. Therefore, as shown in FIGS. 2A and 2B, the projection 22a is separated from the head portion 11 as it cuts into the end outer surface 12a, and as a result, is formed on the end outer surface 12a by this cut. The recess 12b becomes deeper as it moves away from the head 11. Since the protrusion 22a is separated from the head 11, the excess thickness Z does not occur on the side of the head 11 with the protrusion 22a sandwiched therebetween and only on the opposite side of the head 11.

Therefore, it is possible to avoid a situation in which the extra thickness is sandwiched between the head portion 11 and the protrusion 22a, and no step can be formed on the head end surface 11a.

The movable round rolling machine 20 starts to retreat toward the initial position when it advances to the forward limit. In this process, as shown in FIGS. 2B and 2C, the shaft portion 12 does not move, and the protrusion 22 a moves away from the center of the shaft portion 12. As a result, it becomes shallower as it moves away from the head 11,
b is completed. The extra thickness Z generated on the opposite side of the head portion 11 during the formation of the recessed portion 12b is scraped to the opposite head side of the formed recessed portion 12b.

Thus, the head 1 of the connecting rod bolt 10
1 is provided on the outer surface 12a of the end portion of the shaft portion 12 adjacent to
b is formed by round rolling. At the same time, the male screw portion 13 is formed on the tip portion of the shaft portion 12 by rolling. Head end face 1 of connecting rod bolt 10 after processing
1a is flat without any step due to excess thickness.

Further, in the present embodiment, since the under neck neck rolling and the thread rolling are performed at the same time, it is efficient. Moreover, since the round dies 21, 21 used for thread rolling also serve as the axial driving mechanism of the shaft-shaped member, the structure is simple.
Furthermore, since the shaft-shaped member being rolled is supported at two places, the lower neck and the screw part, and its runout is suppressed, the size of the screw part and the squareness of the head end face are smaller than those of conventional thread rolling. The accuracy of can be improved.

In the above embodiment, the design of the lead angles of the round dies 21 and 21 for threading is used to move the shaft-like member during rolling in the axial direction, thereby simplifying the structure. However, the shaft member can be moved in the axial direction by a pressing means such as a piston. Also,
It is not necessary to perform the slimming process and the screwing process at the same time, and only the slimming process may be performed alone while holding the tip of the shaft portion of the shaft-shaped member. In addition, the present invention can be implemented in various modified and improved modes based on the knowledge of those skilled in the art without departing from the scope of the claims.

[0036]

As described above, in the case of the round rolling method of the present invention, when forming the recessed portion on the outer surface of the end portion of the shaft portion adjacent to the flange portion of the shaft-like member by the round rolling, By moving the shaped member axially to the side of the flange, it is possible to prevent excess thickness from being generated on the side of the flange, and there is no step due to excess thickness on the end face of the flange. Can be manufactured with high efficiency by round rolling.

[Brief description of drawings]

FIG. 1 is a diagram showing a main part of an example of a rolling device according to the present invention, in which FIG. 1 (A) is a front view and FIG. 1 (B) is a plan view.

FIG. 2 is an enlarged plan view of a processing portion showing a rolling process step by step.

3A and 3B are diagrams showing a conventional under neck thinning process by round rolling, where FIG. 3A is a front view and FIG. 3B is a plan view.

FIG. 4 is a front view of a connecting rod bolt with a neck-thinned portion.

FIG. 5 is an enlarged view showing a detailed state of conventional under neck thinning processing by round rolling, and is an enlarged view of a B portion in FIG. 3.

[Explanation of symbols]

 10 Connecting Rod Bolt (Shaft Member) 11 Head (Flange) 11a Head End Face 12 Shaft Part 12a End Outer Surface 12b Necked Part 13 Male Threaded Part 20 Round Rolling Machine 21 Round Die for Screw Processing 22 Rounded Molding Dice 22a Projection 30 Blade 40 Pusher 50 Drive mechanism

Claims (1)

[Claims] 1. A shaft-shaped member having a flange portion and a shaft portion extending at a right angle from an end surface of the flange portion, the shaft portion being sandwiched between a pair of shaft portion holding circular dies, and an annular protrusion is provided on an outer surface. By moving one of a pair of the rounding dice for shaving to move toward the shaft-like member from the initial position and retreat to the initial position again, thereby forming an annular shape on the outer surface of the end of the shaft part adjacent to the flange part of the shaft-like member. Is a round rolling method for forming a sunk part, wherein each protrusion of the pair of sneaky round dies is brought into contact with a shaft part of a shaft-shaped member, and then one slush forming round die is centered on the shaft part. A circular rolling method, characterized in that the shaft-shaped member is axially moved to the side of the flange portion at the same time as it is moved forward to form an annular recess.