JP7261060B2 - Method for manufacturing headed parts - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a headed component having a relief groove under the neck.

Conventional methods for manufacturing headed parts are disclosed in Japanese Unexamined Patent Application Publication Nos. 2003-100002 and 2004-100000. First, the method for manufacturing a headed part disclosed in Patent Document 1 includes a first pressing step of integrally forming a large-diameter shaft portion and a small-diameter leg portion by axially pressing a wire rod having a predetermined diameter; A second pressing step of loosely fitting and holding the leg portion and pressing from the distal end side of the leg portion to form a small-diameter shaft portion with an enlarged diameter; and a rolling step of rolling a thread on the small-diameter shaft portion including. The second pressing step is not a step of enlarging the diameter of the leg over the entire length, but a step of forming a relief groove having a diameter of the leg that is the same as the portion adjacent to the large-diameter shaft portion. In other words, in the method of manufacturing a headed part disclosed in Patent Document 1, the small-diameter relief groove is formed under the neck of the large-diameter shaft portion by the second pressing process, not by the rolling process.

On the other hand, the method for manufacturing a headed part disclosed in Patent Document 2 includes a relief rolling step of forming by rolling the relief groove, and the relief rolling step includes a pair of rolling dies arranged oppositely. is a step of rolling the legs by sliding the . In addition, the rolling dies have protrusions formed to gradually bite into the rolling legs. It is formed so as to flow to the part side. In addition, the projection has an inclined wall surface that gradually guides downward the surplus material that has flowed toward the tip of the leg. Then, the angle of inclination is increased. Further, the upper surface of the protrusion is formed so as to gradually push up the surplus material that has flowed toward the large-diameter shaft portion toward the large-diameter shaft portion. be made. Therefore, in the method of manufacturing a headed component disclosed in Patent Document 2, the surplus material that has flowed toward the tip end of the leg is gradually guided downward, so that the bearing surface of the large-diameter shaft portion faces the upper surface of the rolling die. be forced.

Japanese Patent Application Laid-Open No. 2010-42440 JP-A-07-308727

However, in the method for manufacturing a headed part disclosed in Patent Document 1, when the diameter of the leg is expanded, the escape groove having a diameter substantially the same as that obtained in the first pressing step is not constrained. Excess wall tends to flow in the axial direction during diameter expansion. As a result, there is a problem that it is difficult to determine the shape and diameter of the clearance groove, and it is difficult to obtain a headed component with stable quality. On the other hand, the method of manufacturing a headed component disclosed in Patent Document 2 requires rolling dies having upper surfaces and inclined wall surfaces set at different angles, and therefore it takes time to process the rolling dies. There was a problem that the manufacturing cost of the head part increased.

In the method of manufacturing a headed component according to the present invention, a punch having a gap symmetrical to an arbitrary head shape is axially pressed against a receiving piece that holds a wire rod of a predetermined diameter. and a small-diameter shaft portion having substantially the same diameter as the wire rod, and a pair of rolling dies sandwiching the pressed product formed by the pressing step and sliding the rolling dies. A method for manufacturing a headed part, comprising a rolling step of rolling and forming an annular relief groove in a small-diameter shaft portion of a pressed product, wherein an annular protrusion is formed on the contact surface with the punch during the pressing step. An annular recessed groove continuous with the small-diameter shaft portion is formed in the head bearing surface of the pressing piece by using the above-mentioned receiving piece. It is characterized by using a rolling die having a surplus-thickness extruding portion that is inclined upward, and filling the recessed groove with the surplus-thickness generated when forming the front escape groove. It is preferable that the concave groove extends to a predetermined depth along the outer diameter of the small-diameter shaft portion, expands to a predetermined diameter while maintaining this depth, and is rounded up at a predetermined angle while further expanding radially from there.

The method for manufacturing a headed component according to the present invention has the advantage that the material is not wasted because the excess thickness generated in the rolling process can be fed into the large-diameter shaft portion to form the large-diameter shaft portion. . Further, the method for manufacturing a headed part according to the present invention uses a rolling die capable of forming a relief groove in the rolling process, and the rolling die transfers the excess thickness to the large-diameter shaft portion. A surplus-thickness extruded portion is provided for guiding and forming the escape groove. Therefore, not only the escape groove is formed, but also the excess thickness projecting in the radial direction can be built up on the large-diameter shaft portion, so that there is an advantage that the strength of the large-diameter shaft portion can be increased. Further, in the method for manufacturing a headed part according to the present invention, since the recessed groove that can accommodate the extra thickness is formed in the bearing surface of the large-diameter shaft portion in the pressing step, the rolling step is performed in the radial direction. The surplus material to be taken out can be pushed into the concave groove. Therefore, since the excess thickness is configured as a part of the large-diameter shaft portion without protruding from the bearing surface of the large-diameter shaft portion, there is no portion protruding from the bearing surface in the axial direction. There is also the advantage that a head part can be obtained. Further, in the method of manufacturing a headed component according to the present invention, a concave groove is formed in advance, which increases in depth toward the large-diameter shaft portion along the outer diameter of the small-diameter shaft portion and is rounded up at a predetermined angle as it spreads in the radial direction. Therefore, the surplus material guided by the concave groove can be caused to gradually flow in the radially expanding direction from the small diameter side. As a result, since the build-up is performed from the small diameter side, which requires mechanical strength, there is also the advantage that the strength is high and a flat bearing surface can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram for explaining a pressing step of a method for manufacturing a headed component according to the present invention, (a) showing a state in which a wire rod is set, (b) showing a state in which a wire rod is pressed, and (c). indicates the state in which the pressed product is discharged. FIG. 3 is an explanatory diagram for explaining another pressing step of the method for manufacturing a headed component according to the present invention, (a) shows a state in which the wire is set, (b) shows a state in which the wire is pressed, ( c) shows the state in which the pressed product is discharged. FIG. 3 is an operation explanatory diagram for explaining the rolling process of the method for manufacturing a headed part according to the present invention, where (a) is a plan view showing a state in which a pressed product is set, and (b) is A- of (a). It is an A line expanded sectional view. 4A is a plan view showing the initial state of rolling, and FIG. 4B is an enlarged cross-sectional view taken along the line BB of FIG. is. FIG. 5 is an operation explanatory diagram for explaining a state in which rolling is advanced from the state of FIG. 4, (a) is a plan view showing a state in the middle stage of the start of rolling, and (b) is an enlarged cross-sectional view taken along the line CC of (a). is. FIG. 6 is an operation explanatory diagram for explaining a state in which rolling is advanced from the state of FIG. 5, (a) is a plan view showing the state in the latter stage of the start of rolling, and (b) is an enlarged cross-sectional view taken along line DD of (a). is. 4 is a partially cut-away enlarged side view showing the fixed die in view E of FIG. 3; FIG. FIG. 4 is an enlarged cross-sectional view of a part of a main part showing a concave groove of a headed component according to the present invention;

A method for manufacturing a headed component according to the present invention will be described with reference to FIGS. 1 to 8. FIG. First, as shown in FIGS. 6(a) and 6(b), the headed component according to the present invention consists of a large diameter shaft portion 1 and a small diameter shaft extending axially from the large diameter shaft portion 1. and a small-diameter escape groove 3 connecting the small-diameter shaft portion 2 and the large-diameter shaft portion 1 integrally.

Moreover, the headed component according to the present invention may be provided with the large diameter shaft portion 1, the small diameter shaft portion 2, and the escape groove 3, and may be a pin or rivet for fastening members together, or a small diameter shaft portion. There are a wide variety of bolts and tapping screws having a spiral thread (not shown) on the outer circumference of 2, and a worm gear, which is a type of gear.

The method for manufacturing a headed component according to the present invention includes a pressing step of axially pressing a wire rod 5 having a predetermined diameter, and a rolling step of forming an annular escape groove 3 in the pressed product 6 obtained by this pressing step. and a step.

In the pressing step, as shown in FIGS. 1 and 2, the wire rod 5 cut to a predetermined length is held so as to partly protrude from the receiving piece 10 (11), and is arranged opposite to the receiving piece 10 (11). After the punch 15 is brought close to the receiving piece 10 and the large-diameter shaft portion 1 is formed by the punch 15, the punch 15 is returned to eject the pressed product 6 from the receiving piece 10 (11).

The pressing part 6 is one before the escape groove 3 is formed, and comprises a large-diameter shaft part 1 having a flat bearing surface 1b and a small-diameter shaft part 2 having a diameter substantially equal to that of the wire rod 5. . Further, the pressing member 6 may be provided with a recessed groove 1a in which the seat surface 1b is recessed as shown in FIG. 1, or may not be provided with the recessed groove 1a as shown in FIG. good too.

As shown in FIGS. 1(a), 1(b) and 3(b) or FIG. 8, the recessed groove 1a of the pressing member 6 can accommodate excess thickness 2a generated during the rolling process described later. Pre-sized to fit.

Each of the receiving pieces 10 (11) is constructed so that the wire rod 5 and the knockout pin 17 can be inserted. configured as

The protrusion 10a is formed so as to enter the bearing surface 1b of the large-diameter shaft portion 1 and form a recessed groove 1a. As shown in FIG. 8, it is configured to be able to form a concave groove 1a which is rounded up at a predetermined angle.

FIG. 8 shows a groove 1a formed by the projection 10a. The groove 1a extends from the small-diameter shaft portion 2 to the top of the large-diameter shaft portion 1 without changing its diameter and enters the seating surface 1b at a predetermined angle. It expands in the radial direction and increases in depth, then expands in the radial direction while maintaining the depth, and is rounded up to the seat surface 1b at a predetermined angle. Therefore, the projection 10a has an annular configuration that is raised opposite to the concave groove 1a shown in FIG.

The punch 15 is a mold for pressing the wire rod 5 held by the receiving piece 10 (11) in the axial direction to plastically deform it to form the large-diameter shaft portion 1, and contacts the receiving piece 10 (11). It is configured to be accessible until just before Moreover, since the punch 15 is provided with a convex portion 15a having a cross shape or the like, the driving portion 1c having a cross shape or the like as shown in FIGS. can be transferred.

The knockout pin 17 is normally inserted through the receiving piece 10 (11) as shown in FIG. 1(a) or FIG. It consists Further, as shown in FIG. 1(b) or FIG. 2(b), it is constructed so as to withstand the pressing force caused by the approach of the punch 15, so that the wire rod 5 can be plastically worked.

1(c) and 2(c), the knockout pin 17 slides so as to protrude partly from the end surface of the receiving piece 10 (11) in accordance with the return of the punch 15 shown in FIGS. 1(c) and 2(c). ) or the pressing piece 6 shown in FIG.

The rolling process is a process using a pair of rolling dies as shown in FIGS. be.

The rolling dies are a fixed die 20 and a moving die 21 arranged at a predetermined interval, and the moving die 21 is configured to be parallel and relatively movable with respect to the fixedly arranged fixed die 20. ing. As shown in FIG. 3(b), the rolling dies hold the small-diameter shaft portion 2 of the pressed product 6 supplied thereto, and support the pressed product 6 with the bearing surface 1b slightly raised. is configured to

Further, as shown in FIGS. 3 to 6, the rolling dies gradually enter deeply into the small-diameter shaft portion 2 in the process of rolling while holding the small-diameter shaft portion 2, as shown in FIG. 6(b). Extruded portions 20a and 21a for forming the escape groove 3 are provided.

The extruded portions 20a and 21a have a small pointed shape at the beginning of rolling, as shown in FIG. 4(b). It forms a projection shape with increased thickness, and forms a shape that finishes the escape groove 3 as shown in FIG. As shown in FIG. 7, the extruded portion 20a (21a) has a triangular area with an acute angle and a rectangular area. ).

Here, the pressing process and the rolling process for manufacturing the headed component according to the present invention will be described in order. First, the pressing process for forming the pressed product 6 from the wire 5 will be described with reference to FIG.

The wire rod 5 is supplied to a receiving piece 10 slidably provided with the knockout pin 17 and is in contact with the end surface of the knockout pin 17 . At this time, the wire rod 5 projects from the receiving piece 10 by a predetermined length and is supported by the receiving piece 10, as shown in FIG. 1(a).

The punch 15 moves in a direction approaching the receiving piece 10, thereby axially pressing the protruding wire rod 5 as shown in FIG. 1(b). As a result, the wire rod 5 is transformed into a press piece 6 comprising the large-diameter shaft portion 1 having the concave groove 1a and the driving portion 1c and the small-diameter shaft portion 2. As shown in FIG.

Then, the punch 15 starts to return to its original position, so that it separates from the large-diameter shaft portion 1 . At this time, the knockout pin 17 slides along the moving direction of the punch 15 as shown in FIG.

Thus, the pressing process is a process of performing one cycle from supplying the wire rod 5 to the receiving piece 10 to discharging the pressed product 6 by the knockout pin 17. 6 is obtained. 2(a) to 2(c) also show the same state of the pressing process as described above, but the difference from FIG. 1(a) to FIG. Since the only point is that the recessed groove 10a is not provided, a series of explanations will be omitted.

Next, the rolling process for forming the escape groove 3 in the pressed product 6 will be described with reference to FIGS. 3 to 6. FIG. When the moving die 21 is positioned on the right side with respect to the fixed die 20 as shown in FIGS. 2 is fed to the rolling die so that it is in a pressed state.

At the beginning of rolling shown in FIG. 4A, the movable die 21 moves leftward from the position shown in FIG. there is As a result, the surplus-thickness extruding portions 20a and 21a of the fixed die 20 and the movable die 21 gradually bite into the rolling small-diameter shaft portion 2, and gradually form a triangular cross-section as shown in FIG. 4(b). Therefore, a surplus thickness 2a projecting radially from the small-diameter shaft portion 2 is generated.

The excess thickness 2a gradually increases in the middle stage of the start of rolling shown in FIG. As a result, the excess thickness 2a flowing toward the large-diameter shaft portion 1 enters the concave groove 1a located in the large-diameter shaft portion 1, and as can be seen from the difference between FIGS. The volume of the recessed groove 1a is reduced more than that.

Before long, the extruded portions 20a and 21a change from the triangular or trapezoidal shape to the quadrangular shape shown in FIG. An annular escape groove 3 is formed between the large-diameter shaft portion 2 and the small-diameter shaft portion 2 and finished. Moreover, at this time, since the inclined upper surface 20b (21b) converges to a flat surface, the excess thickness 2a that gradually increases during this convergence is offset by the recessed groove 1a formed in the large-diameter shaft portion 2. sent to. Therefore, in the rolling step, the area of the bearing surface 1b can be made wider and flatter than that of the pressed product 6 obtained in the pressing step.

Further, if the recessed groove 1a has the shape shown in FIG. 8, the excess wall 2a generated by biting into the excess wall extruding portions 20a and 21a is likely to flow from the small diameter portion to the large diameter portion of the recessed groove 1a. , the recessed groove can be made smaller and built up so as to gradually expand in diameter. Therefore, the bearing surface 1b can be finished flat over a wide range, and the strength of the large-diameter shaft portion 1 can be increased.

The headed component according to the present invention may be provided with the large-diameter shaft portion 1, the small-diameter shaft portion 2, and the escape groove 3, and may be a pin or rivet for fastening members together, or a small-diameter shaft portion. There are a wide variety of bolts and tapping screws having a spiral thread (not shown) on the outer circumference of 2, and a worm gear, which is a type of gear.

Further, when forming the headed part into a bolt or a tapping screw, the rolling dies are provided with a plurality of inclined grooves (not shown) on their facing surfaces. 3 and the threads are molded simultaneously.

REFERENCE SIGNS LIST 1 Large-diameter shaft portion 1a Concave groove 1b Bearing surface 2 Small-diameter shaft portion 2a Surplus thickness 3 Escape groove 5 Wire rod 6 Pressed piece 10 Receiving piece 10a Projection 15 Punch 17 Knockout pin 20 Fixed die 21 … Moving die

Claims (2)

By axially pressing a punch having a gap symmetrical with an arbitrary head shape against a receiving piece holding a wire of a predetermined diameter, a head having a diameter larger than that of the wire and a diameter smaller than that of the wire are obtained. a pressing step of molding the shaft;
a rolling step of sandwiching the pressed product formed by the pressing step between a pair of rolling dies and sliding the rolling dies to form an annular escape groove in the small-diameter shaft portion of the pressed product; A method for manufacturing a headed component comprising:
At the time of the pressing step, the receiving piece having an annular protrusion formed on the contact surface with the punch is used, and an annular recessed groove continuous with the small-diameter shaft portion is formed on the head bearing surface of the pressing piece,
During the rolling process, a rolling die formed with a surplus-thickness extruded portion that gradually protrudes sideways and has an upper surface that is gradually inclined upward is used to form the surplus that is generated when the front relief groove is formed. A method for manufacturing a headed component, characterized by filling the groove with meat . The concave groove extends to a predetermined depth along the outer diameter of the small-diameter shaft portion, widens to a predetermined diameter while maintaining this depth, and is rounded up at a predetermined angle while further expanding radially from there. The manufacturing method of the headed part according to claim 1 .

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