JPH10225744A - Method and device for manufacturing hollow product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To finely break slugs, which are generated at the time of forming an attaching hole of a prescribed diameter by punching a prepared hole on the wall of a hollow product, and to discharge the broken slugs out of the hollow part. SOLUTION: A hollow intermediate stock is formed which has a prepared hole on one side of the wall; then, with that prepared hole positioned on the punching side, by means of a punch 7 which is provided at the tip end with a cross-sectionally quadratic prism shaped cutting part 7e and a cylindrical punching part 7c, plural notches are thereby radially formed around the prepared hole by the cutting part 7e so that the tip end is positioned on the circumference of a through-hole (a) to be formed; after that, with punching performed around the prepared hole by the punching part 7c, the through-hole with a prescribed diameter is formed while the slugs (f) from the punching are broken into plural pieces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a hollow product and an apparatus for manufacturing the same, and to a method for connecting and fixing a metal supply pipe used as a fluid supply path for oil, air, etc. to various devices, mainly to a fluid supply portion. TECHNICAL FIELD The present invention relates to a manufacturing method for manufacturing an eye joint and the like used in a device and a manufacturing apparatus therefor.

[0002]

2. Description of the Related Art For example, as shown in FIG. 17, an eye joint used for an oil supply path of an automobile or the like has a hollow cylindrical shape and has through holes a and b opposed to each other at upper and lower walls thereof.
The structure is such that a connection hole d is formed in the side wall. A small-diameter metal supply pipe 31 is fixed to the connection hole d of the eye joint B by brazing means, and an eyebolt 32 having flow passages 32a and 32b therein is provided in the through holes a and b. Is inserted, and the eye joint 32 is screwed and fixed to the wall surface of the fluid supply unit 33 by the eye bolt 32. Thus, the eye joint B
Is used, for example, so that oil from the fluid supply unit 33 can be supplied to the supply pipe 31 through the flow passages 32a and 32b of the eye bolt 32 and the hollow portion c serving as a flow path of the eye joint B. Incidentally, in FIG.
Are packings.

Conventionally, when manufacturing the above-described eye joint B, a method of manufacturing an eye joint B having a hollow portion c serving as a flow path without an internal cutting operation is disclosed in, for example, Japanese Unexamined Patent Application Publication No. No. 241372.

In the method of manufacturing the eye joint B disclosed in this publication, first, in a first step, a metal cylindrical material is forged into a flat shape to form a shallow concave portion on the upper surface as shown in FIG. In the second step, the center of the upper surface of the metal column Y1 is depressed inward to form a bottomed cylinder Y2 as shown in FIG. Then, in a third step, the opening-side end of the bottomed cylindrical body Y2 is bent inward to form a hollow molded product Y3 having a through hole a on the upper surface as shown in FIG. After that, the fourth
In the step (3), the upper surface and the bottom surface of the hollow molded product Y3 are forged in parallel, and the through hole a on the upper surface is shaped to form a hollow molded product Y4 having the through hole a on the upper surface as shown in FIG. Thereafter, in the fifth step, a through hole b provided on the bottom surface of the hollow molded product Y4 and a connection hole d provided on the side surface are formed by cutting to manufacture an eye joint B as shown in FIG. ing.

In another manufacturing method, a through hole b is punched in the bottom surface of the hollow molded product Y3 at the same time as the top surface of the hollow molded product Y3 is shaped in the fourth step, and the through hole b on the bottom surface is shaped in a fifth step. Is also disclosed.

[0006]

However, according to the former manufacturing method of the above two manufacturing methods, the eye joint A having the hollow portion c as a flow path can be manufactured without an internal cutting operation. However, in the fifth step, it is necessary to form a through hole b on the bottom surface of the bottomed cylindrical body by cutting separately from the forging, and further, the cutting chips enter the hollow portion c, There is a problem that a troublesome operation of removing the cutting waste from the inside of the hollow portion c is required.

Further, according to the latter manufacturing method, in the fourth step, the bottom surface is punched out by a molding pin provided on the die while the through hole a on the upper surface of the hollow molded product Y3 is positioned on the punch side. As a result, the through-hole b is formed, but in this case, a circular punched cutting waste is generated by the punching. Then, the cutting waste is left in the hollow portion c of the hollow molded product Y3, and there is a problem that it is difficult to remove the cutting waste outside.

If the diameter of the through hole b formed on the bottom surface of the hollow molded product Y3 is smaller than that of the through hole a on the upper surface, the cutting chips can be discharged from the through hole a on the upper surface. Actually, since the through hole b on the bottom surface and the through hole a on the top surface have the same diameter because they are used for connection and fixation by the eyebolts 32 in the middle of the supply path, as described above, Will remain inside.

Therefore, according to the present invention, when manufacturing a hollow product such as an eye joint in which a through hole having a predetermined diameter is formed by punching a wall of a hollow molded product, cutting chips generated by the punching are divided simultaneously with the punching. It is another object of the present invention to provide a method of manufacturing a hollow product such as an eye joint and the like, which can discharge the cutting waste to the outside without remaining in the hollow portion, and an apparatus for manufacturing the same.

[0010]

Means for Solving the Problems In order to solve the above problems, the present invention is characterized in that it is configured as follows.

That is, first, the invention of claim 1 of the present application (hereinafter referred to as the first invention) is a method of manufacturing a hollow product in which a through hole having a predetermined diameter is formed by punching a wall of a hollow molded product. First, a hole which is smaller than the diameter of the through hole and is formed as a lower hole of the through hole is formed on the wall of the hollow molded product, and then, around the lower hole, the tip is substantially on the circumference of the through hole. A plurality of cuts are formed radially so as to be positioned, and thereafter, by punching operation, a punching operation is performed around the pilot hole, so that the cut waste to be punched is divided into a plurality of cut holes and a through hole having a predetermined diameter is formed. Is formed.

According to a second aspect of the present invention (hereinafter, referred to as a second aspect), a material is supplied to a multi-stage press forming machine having a plurality of press forming stations constituted by a die and a punch facing each other. As a method of manufacturing an eye joint in which a through-hole of a predetermined diameter is formed by punching the wall of a hollow molded product by stepwise forging the material, first, of the plurality of forging stations, In the forging station, a hollow molded product having a hole that is smaller than the diameter of the through hole and has a hole serving as a lower hole of the through hole is forged, and then, in a forging station on a stage subsequent to the predetermined forging station, the hollow molding is performed. In a state where the lower hole of the molded article is located on the punch side, the punching operation of one punch causes the tip to be positioned substantially on the circumference of the through hole around the lower hole. A plurality of cuts are formed radially so as to perform a punching process around the pilot hole, and a through hole of a predetermined diameter is formed while dividing the cutting waste to be punched into a plurality of cut chips. .

Further, according to a third aspect of the present invention (hereinafter referred to as a third aspect), a material is supplied to a multi-stage press forming machine having a plurality of press forming stations constituted by a die and a punch facing each other. By stepwise forging the material, as an eye joint manufacturing apparatus for manufacturing an eye joint having a through hole of a predetermined diameter formed by punching a wall of a hollow molded product, among the plurality of steps of the forging station, Around the periphery of the pilot hole, at a tip end of a punch in a forging station at a later stage than a predetermined forging station for forging and forming a hollow molded product having a hole that becomes a lower hole of the through hole with a diameter smaller than the diameter of the through hole. A notch processing portion for forming a plurality of notches radially so that a tip thereof is located substantially on the circumference of the through hole is provided, and the notch is formed at an intermediate portion of the punch. Punched around the lower hole formed,
It is characterized in that a column-shaped punching portion for forming a through-hole with a predetermined diameter is provided while dividing the punched cutting waste into a plurality.

By using such means, according to the above-mentioned inventions, the following effects can be obtained.

According to the manufacturing method of the first invention described above, when manufacturing a hollow product having a through-hole having a predetermined diameter formed by punching the wall of the hollow molded product, first, the through-hole is formed in the wall of the hollow molded product. Forming a pilot hole that is a through hole with a diameter smaller than the diameter of the through hole, and thereafter, forming a plurality of cuts radially around the pilot hole so that the tip is located substantially on the circumference of the through hole, Thereafter, a punching operation is performed around the prepared hole by a punching operation, whereby a through hole having a predetermined diameter is formed while dividing the cut chips to be punched into a plurality of pieces. Accordingly, when performing the punching process on the pilot hole, the cutting waste punched in a ring shape enters the hollow portion in a state of being divided into a plurality of pieces by the cut. As a result, the cutting chips that have been divided and punched out can be discharged at any time from the formed through holes, and do not remain in the hollow portion.

Further, according to the manufacturing method of the second invention, when manufacturing an eye joint having a through-hole of a predetermined diameter formed by punching a wall of a hollow molded product, the multi-stage type forging machine is used. At a predetermined forging station among a plurality of forging stations in the machine, at a predetermined forging station, a hollow molded article having a hole smaller than the diameter of the through hole and serving as a lower hole of the through hole is forged, and thereafter, the predetermined forging station is formed. At a later stage of the forging station, a punching operation by a single punch having a notch processing portion and a punching processing portion at the tip portion causes the tip to be located substantially on the circumference of the through hole around the pilot hole. As described above, a plurality of cuts are formed radially, and subsequently, a punching process is performed around the prepared hole to form a through hole having a predetermined diameter. With this, an eye joint having a hollow portion as a flow path can be manufactured without a cutting operation of the inside by a multi-stage type head forming machine, and when the punching process is performed on the prepared hole, cutting waste punched in a ring shape Are cut into the hollow portion at the same time as the punching, and the punched chips are easily discharged from the formed through hole, and do not remain in the hollow portion.

Further, according to the manufacturing apparatus of the third invention, when manufacturing an eye joint having a through hole having a predetermined diameter formed by punching a wall of a hollow molded product, the multi-stage forging machine is used. Among a plurality of forging stations in the machine, a forging station at a stage subsequent to a predetermined forging station for forging a hollow molded product having a diameter smaller than the diameter of the through hole and having a hole serving as a lower hole of the through hole. A plurality of cuts are radially formed around the prepared hole by the cutting operation provided at the tip of the punch by the punching operation of the punch so that the tip is substantially positioned on the circumference of the through hole. Subsequently, a cylindrical punching portion provided at an intermediate portion of the punch is used to punch around the prepared hole where the cut is formed. It will form a through hole having a predetermined diameter is subjected. With this, an eye joint having a hollow portion as a flow path can be manufactured without a cutting operation of the inside by a multi-stage type head forming machine, and when the punching process is performed on the prepared hole, cutting waste punched in a ring shape Is split at the same time as the punching and enters the hollow portion. As a result, the cutting waste is easily discharged from the formed through hole, and does not remain in the hollow portion.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

The drawings show an embodiment in which an eye joint A as a hollow product having a through-hole having a predetermined diameter formed by punching a wall of a hollow molded product is produced by a multi-stage press forming machine. In this case, the eye joint A has a hollow columnar shape as shown in FIG. 6, has through holes a and b opposed to each other at an opposing wall thereof, and has a hollow portion c serving as a flow path therein,
Further, a connection hole d is formed in the side wall.

FIGS. 1 to 6 show the respective molding steps in the case where the above-mentioned eye joint A is manufactured from the material X by the multistage forging machine 1 having a plurality of forging stations S1 to S5 as shown in FIG. Shows the change in the shape at.

First, a flat cylindrical material X as shown in FIG. 1 is subjected to upsetting at a first stage forging station S1 to form a flat cylindrical shape as shown in FIG. To form a first intermediate material X1. Then
In the second stage forging station S2, a second intermediate material X2 having a cylindrical shape with a bottom and a shallow concave portion on the upper surface as shown in FIG. 3 is formed. Thereafter, at the third stage forging station S3, a bottom (hereinafter, referred to as a prepared hole) a 'serving as a prepared hole of the through hole a is formed on the bottom surface as shown in FIG. Is formed into a third intermediate material X3 having a hollow portion c slightly bent inside. Then, at the fourth stage forging station S4, the third stage as shown in FIG.
A fourth intermediate material (hollow molded article) X4 having a hollow portion c obtained by further bending the opening end of the intermediate material X3 is formed. Further, in the fifth stage forging station S5, by performing radial cutting and circular punching on the prepared hole a 'of the fourth intermediate material X4 and simultaneously forging the opening end, As shown in FIG. 6, an eye joint as a final molded product is formed by forming one flat wall having a through hole a having a predetermined diameter and the other flat wall having a central through hole b. A is formed. A connection hole d as shown in FIG. 6 is formed on the side surface of the eye joint A by cutting or punching at a forging station (not shown) subsequent to the fifth forging station S5. You. In that case,
Since the punched waste generated when forming the connection hole d is smaller in diameter than the through holes a and b, it can be discharged to the outside.

Next, a description will be given of the configuration of a multi-stage press forming machine 1 as a manufacturing apparatus for manufacturing the eye joint A from the material X by the press forming.

As shown in FIG. 7, the die forming machine 1 has a plurality of die-side mold members 4... 4 arranged side by side on a die block 3 fixed to a machine base 2. A plurality of punch-side die members 6... 6 are attached to a ram 5 that reciprocates so as to approach and separate from the respective die-side die members 4.

More specifically, as shown in FIG. 8, the die side die member 4 at the first stage forging station S 1 is composed of a receiving seat 11 a and a holder 1 supported in the die block 3.
3a, the pressure receiving body 14a and the die 15a supported in the holder 13a, and the forged first intermediate material X1 into the die 1
And a movable pin 16a for pushing out from 5a to the outside. The movable pin 16a is connected to the die 1
Knockout means (not shown) provided so as to penetrate the center of 5a and driven in synchronization with the movement of ram 5
Is driven by the movement of the moving shaft 16a '. Reference numeral 16a ″ denotes a spring for returning the movable pin 16a.

On the other hand, the punch-side mold member 6 comprises a ram 5
A support member 18a fixed to the support member 1;
The pressure receiving member 19a is supported by the ram 5 within 8a, and the punch 7 is supported by the pressure receiving member 19a within the support member 18a via the linking member 20a.

Then, at the first stage forging station S1, the central portion at one end and the outer peripheral portion at the other end of the material X are forged, thereby forming a flat cylindrical shape having a sloped bottom surface.
An intermediate material X1 is formed.

As shown in FIGS. 9 to 11, the die side mold members 4 to 4 in the second to fourth stage forging stations S2 to S4 are supported in the respective die blocks 3 to 3, respectively. Seats 11b to 11d, intermediate seats 12b to 1
2d and holders 13b to 13d, pressure receiving bodies 14b to 14d supported in the holder 13, and dies 15b to 15d
And the intermediate material X2 to X4 formed by forging and die 15b to
Movable members 16b to 16d for pushing out from 15d,
The movable members 16b to 16d are constituted by fixed molding pins 17b to 17d which protrude into the die from inside. The movable members 16b to 16d are connected to a moving shaft 16 of knockout means (not shown) driven in synchronization with the movement of the ram 5.
The movement of b 'to 16d' causes the plurality of push pins 16b "to move.
To 16d ". Reference numeral 17b 'to
17d 'is a spring for returning the movable members 16b to 16d.

On the other hand, the punch-side mold member 6 is
The support members 18b to 18d are fixed to the support members 18b to 18d, and the punches 7 to 7 are supported by the pressure receiving members 19b to 18d supported by the ram 5 in the support members 18b to 18d via the link members 20b to 20d. ing.

In the second stage forging station S2, the first intermediate material X1 is formed by forging so as to further indent the one end recess, thereby forming a bottomed cylindrical shape having a shallow recess on the lower surface. (2) An intermediate material X2 is formed.
In the third-stage forging station S3, by forging the opening end of the second intermediate material X3 inward so as to bend inward and simultaneously punching the bottom surface, the diameter of the through hole a is smaller than that of the through hole a. A third intermediate material X3 having a pilot hole a 'and a hollow portion c having a bottomed cylindrical opening slightly bent inward is formed. Thereafter, in the fourth stage forging station S4, the fourth intermediate material having the hollow portion c having the open end portion largely bent by forging the open end portion of the third intermediate material X3 to be greatly bent. (Intermediate molded product) X4 is formed. In addition, the punched waste a ″ punched in the third-stage forging station S3
Is a discharge hole 7 ′ provided in the punch 7 and a linking member 20.
c is discharged outside through the discharge passage 20c '.

As shown in FIG. 12, the die side die member 4 at the fifth stage forging station S5 includes a receiving member 11e supported by the die block 3, an intermediate seat member 12e, and a holder 13e. And a pressure receiving body 14e and a die 15e supported in the holder 13e, a movable member 16e for extruding the forged molded product from the die 15e, and a fixed molding projecting from the inside of the movable member 16e to the die 15e side. And a pin 17e. The movable member 16e
Is driven via a plurality of push pins 16e "by the movement of a movement shaft 16e 'of a knockout means (not shown) which is driven in synchronization with the movement of the ram 5. Further, reference numeral 17 denotes
e 'is a spring for returning the movable member 16e.

On the other hand, the punch side mold member 6 is
A support member 18e fixed to the support member 1;
8e, a pressure receiving member 19e supported in
8e and a punch 7 supported via a pressure receiving member 19e. When the punch 7 is driven, the fourth intermediate material X4 is pressed toward the die side to forge the open end, and when the retreat is performed, the final molded product A formed from the die side is pressed from the die side. A stripper 21e for preventing slipping out is inserted. This stripper 21e
Is a pair of plate members 24e, 25e held on the front surface of the support member 18e by the pushing member 22e via the rod 23e.
Is sandwiched between.

In the fifth stage forging station S5, the fourth intermediate material X4 is subjected to a punching process for setting the final dimension of the pilot hole a 'and a forging process for the opening end side. Thus, an eye joint A having through holes a and b facing each other and having a hollow portion c serving as a flow path is formed. In FIG. 12, reference numerals 26e and 27e represent
It is a link member interposed between the punch 7 and the pressure receiving member 19e.

Here, the configuration of the punch 7 used in the fifth forging station S5 will be described.

As shown in FIGS. 13 and 14, the punch 7 has a base portion 7a having a predetermined diameter, a body portion 7b having a slightly smaller diameter following the base portion 7a, and a small portion following the body portion 7b. It is provided with a columnar punched portion 7c having a small diameter, and a rectangular column-shaped cutout portion 7e that follows the processed portion 7c via an escape groove 7d. The cut portion 7e is provided at the forefront of the punch 7, and is punched into a pilot hole a 'to form a plurality of cuts e... E radially prior to the processing by the punching portion 7c. I have.

Here, as shown in FIG. 14, the radius r of the punched portion 7c is equal to the center of the cut portion 7e, in other words, the length L from the center of the pilot hole a 'to the cut end. The distal ends of the radial cuts e... E formed around the prepared hole a ′ of the fourth intermediate material X4 are set so as to be positioned on the circumference of the through hole a formed by the punched portion 7c. ing.

The punch 7 can be easily manufactured by, for example, the following manufacturing method.

That is, a bar having a diameter equal to the outer diameter of the base 7a and having a predetermined length is used, one end of the bar is left as the base 7a, and the other outer periphery is cut to the diameter of the body 7b. Then
At the foremost portion, a square pillar portion inscribed in the outer peripheral diameter is formed by cutting, and then, the tip including the square pillar portion is cut to the diameter of the stamped portion, thereby forming the stamped portion having the radius r. 7c and the notched portion 7e having the length L are formed.

It is sufficient that the cross-section of the cut portion 7e is radial. The cross-section may be square, as shown in the figure, or may be appropriately selected, such as a triangle, a pentagon, or a star. Can be.

Next, the molding operation of the eye joint A in the fifth stage forging station X5 of the multistage forging machine having the above-described configuration will be described.

After the hollow fourth intermediate material X4 in which the pilot hole a 'is formed as shown in FIG. 5 is forged at the first to fourth forging stations X1 to X4, a material transfer device is appropriately provided. As a result, the fifth stage forging station S shown in FIG.
5, the punching operation of the forging station S5 by the punch 7 is performed. In that case, first,
Prior to the punching of the prepared hole a 'formed in the fourth intermediate material X4 by the punching portion 7c at the tip of the punch 7, the cutting portion 7e at the foremost portion of the hole a' as shown in FIG. A plurality of cuts e... E having a length L ′ from the center to the cut end that is substantially the same as the radius r ′ of the through hole a to be formed are formed in the pilot hole a ′. That is, a plurality of cuts e... E are radially formed in the pilot hole a ′ such that the length from the center to the cut end is located on the circumference of the through hole a. After the cuts e... E are formed, as shown in FIG. 16, the periphery of the prepared hole a 'is punched by the punching portion 7c. As a result, the cutting chips f... F cut into a thin ring shape in the finishing portion 7c are divided into a plurality of pieces and enter the hollow portion c. As a result, the finely divided cutting waste f ...
f can be discharged from the through hole a or b at any time, and does not remain in the hollow portion c.

On the other hand, when the punch 7 is driven,
At the same time, the stripper 21e presses the fourth intermediate material X4 toward the die, whereby the opening end is forged and formed along the outer peripheral surface of the forming pin 17e provided at the center on the die side, thereby forming a flat shape. The other end face is formed and the through hole b is formed at the center.

When the punch 7 is retracted, the pushing member 22e advances toward the die relative to the punch 7, and moves.
As a result, the punch 7 retreats with the stripper 21e remaining in the die 15e via the rod 23e and the plates 24e and 25e. As a result, the stripper 21e
The punch 7 is retracted in a state where the eye joint A, which is the final molded product formed by forging, is prevented from falling out of the die side.

In this manner, the eye joint A can be forged by the multi-stage forging machine, and the cutting chips f... F punched at the time of the forming are finely divided simultaneously with the punching and enter the hollow portion c. The cutting waste f
.. F are easily discharged from the formed through holes a and the like. Further, the punching operation by one punch 7 simultaneously applies the radial cuts e... E to the pilot hole a ′ of the intermediate material X4 and the punching process by punching around the pilot hole a ′ to obtain a predetermined diameter. Since the through holes a are formed, the number of forging steps can be reduced. In addition, 1
Cutting part 7e and punching part 7
c, the centers of both processing portions 7c and 7e can be accurately matched, whereby the cutting chips f can be satisfactorily divided by cutting and punching, and the inner surface of the through hole a can be formed. It is possible to prevent the incision marks from being left in the area.

In the above-described embodiment, the method of manufacturing the eye joint A has been described. However, the present invention is not limited to the eye joint A at all. It is needless to say that the present invention can be applied to a case where a through hole having a predetermined diameter is formed.

[0045]

As described above, according to the method for manufacturing a hollow product according to the first invention of the present application, when manufacturing a hollow product having a through hole of a predetermined diameter formed by punching a wall of a hollow molded product. First, a pilot hole is formed on the wall of the hollow molded article, which is a through hole having a diameter smaller than the diameter of the through hole. Thereafter, the length from the center to the cut end of the pilot hole is formed in the pilot hole. A plurality of cuts are formed radially so as to be located on the circumference, and then, by punching operation, punching is performed around the prepared hole, thereby dividing the cut chips to be punched into a plurality of pieces. Since a through hole having a diameter is formed, when punching is performed on the pilot hole, the cutting waste punched in a ring shape enters the hollow portion in a state divided into a plurality of pieces by the cut. Become Fruit, divided by cuttings punched, it becomes possible to optionally discharged from the through-hole formed, thereby preventing such remains in the hollow portion.

Further, according to the eye joint manufacturing method of the second invention, a multi-stage forging machine is used, and among the plurality of forging stations in the forging machine, a predetermined forging station is used to form the through hole. A hollow molded product having a hole that becomes a lower hole of the through hole with a diameter smaller than the diameter is forged, and then, at a forging station on a side subsequent to the predetermined forging station, a notch processing part and a punching processing part at the tip end. A plurality of cuts are radially formed around the pilot hole by a punching operation so that the tip is located substantially on the circumference of the through hole. Since a through hole with a predetermined diameter is formed by punching the hollow, a hollow as a flow path without internal cutting work by a multi-stage press forming machine It is possible to manufacture an eye joint having, when punching against the lower hole,
Since the cutting waste punched in a ring shape is divided at the same time as the punching and enters the hollow portion, the cutting waste is easily discharged from the through hole formed and remains in the hollow portion. Disappears.

Further, the punching operation by one punch is simultaneously performed on the pilot hole by radial cutting and punching around the pilot hole to form a through hole having a predetermined diameter. The number of forging steps can be reduced. In addition, since the notch processing part and the punching processing part are provided in one punch, it becomes possible to make the centers of both processing parts exactly coincide with each other, so that the cutting chips can be divided well by the cutting and the punching processing. In addition, it is possible to prevent cut marks from remaining on the inner surface of the through hole.

Further, according to the apparatus for manufacturing an eye joint according to the third invention, a multi-stage forging machine is used, and a plurality of forging stations of the forging machine have a diameter smaller than the diameter of the through hole. In a forging station subsequent to a predetermined forging station for forging a hollow molded product having a hole serving as a pilot hole of a through-hole, by a punching operation of a punch of the forging station, a notch portion provided at a tip portion of the punch is formed. , Around the pilot hole,
A plurality of cuts are formed radially so that the tip is located substantially on the circumference of the through-hole, and subsequently, the cuts are formed by a cylindrical punching portion provided in the middle of the punch. Since a punched hole was formed around the formed pilot hole to form a through hole with a predetermined diameter, an eye joint having a hollow portion as a flow path without internal cutting work by a multi-stage type forging machine. In addition to being able to be manufactured, when performing punching on the pilot hole, it becomes possible to separate the cutting waste punched in a ring shape into the hollow portion simultaneously with the punching. As a result, the cutting waste is easily discharged from the formed through hole, and does not remain in the hollow portion.

Moreover, the punching operation by one punch simultaneously forms a radial cut into the pilot hole and a punching process by punching around the pilot hole to form a through hole having a predetermined diameter. Thus, the number of forging steps can be reduced. In addition, since one punch is provided with a notch processing part and a punching processing part,
It is possible to exactly match the centers of both processing parts,
As a result, it is possible to satisfactorily divide the cutting waste by cutting and punching, and it is possible to prevent cut marks from being left on the inner surface of the through hole.

[Brief description of the drawings]

FIG. 1 is a diagram showing a shape of a material used in an embodiment of the present invention.

FIG. 2 is a view showing a shape of a first intermediate material formed in a first-stage forging station.

FIG. 3 is a view showing a shape of a second intermediate material formed in a second-stage forging station.

FIG. 4 is a view showing a shape of a third intermediate material formed in a third-stage forging station.

FIG. 5 is a view showing a shape of a fourth intermediate material formed in a fourth forging station.

FIG. 6 is a view showing a shape of an eye joint formed in a fifth forging station.

FIG. 7 is a schematic explanatory view of a multi-stage press forming machine used in the embodiment of the present invention as viewed from a plane.

FIG. 8 is a cross-sectional view showing a configuration of a mold member in the first stage forging station.

FIG. 9 is a cross-sectional view showing a configuration of a mold member in the second-stage forging station.

FIG. 10 is a cross-sectional view showing a configuration of a mold member in the third-stage forging station.

FIG. 11 is a cross-sectional view showing a configuration of a mold member in the fourth stage forging station.

FIG. 12 is a sectional view showing a configuration of a mold member in the fifth stage forging station.

FIG. 13 is a plan view of a punch used for a mold member in a fifth-stage forging station.

FIG. 14 is a front view of the punch.

FIG. 15 is an explanatory diagram showing a radial cutting state of the fourth intermediate material at the fifth forging station.

FIG. 16 is a cross-sectional view of a main part showing the punching state.

FIG. 17 is an explanatory diagram showing a use state of the eye joint.

FIG. 18 is a view showing a shape of an intermediate material formed in a first step of a conventional manufacturing method.

FIG. 19 is a view showing the shape of the intermediate material formed in the second step.

FIG. 20 is a view showing a shape of an intermediate material formed first in the third step.

FIG. 21 is a view showing a shape of an intermediate material formed later in the third step.

FIG. 22 is a view showing the shape of the eye joint formed in the fifth step.

[Explanation of symbols]

 Reference Signs List 7 punch 7c punching part 7e cutting part 15a to 15d die X material X1 to X4 intermediate material A final molded product a, b through hole a 'pilot hole

Claims (3)

[Claims] 1. A method for producing a hollow product having a through-hole having a predetermined diameter formed by punching a wall of a hollow molded product, wherein the hollow product has a smaller diameter than the diameter of the through-hole. Forming a hole that becomes a pilot hole of the through hole, and thereafter forming a plurality of cuts radially around the pilot hole so that the tip is located substantially on the circumference of the through hole; A punching process is performed around the pilot hole by the driving operation of (1) to form a through hole having a predetermined diameter while dividing the cutting waste to be punched into a plurality of pieces. 2. A hollow molded product by supplying a material to a multi-stage forging machine having a plurality of forging stations constituted by a die and a punch facing each other, and forging the material in a stepwise manner. A method of manufacturing an eye joint in which a through hole having a predetermined diameter is formed by punching a wall of a plurality of forging stations, first, among the plurality of forging stations, at a front end side forging station, a diameter smaller than the diameter of the through hole. In a state in which a hollow molded product having a hole serving as a pilot hole of the through hole is forged, and then, in a forging station downstream of the predetermined forging station, the pilot hole of the hollow molded product is positioned on the punch side. Under the above, a plurality of cuts are radially formed around the prepared hole by a punching operation so that the tip is substantially positioned on the circumference of the through hole. A method for manufacturing an eye joint, wherein a punching process is performed around the pilot hole to form a through hole having a predetermined diameter while dividing the cutting chips to be punched into a plurality of pieces. 3. A hollow molded product by supplying a material to a multi-stage forging machine having a plurality of forging stations constituted by a die and a punch facing each other, and forging the material in a stepwise manner. An eye joint manufacturing apparatus for manufacturing an eye joint in which a through hole having a predetermined diameter is formed by punching in a wall of the plurality of forging stations, wherein the diameter of the through hole is smaller than the diameter of the through hole. At the tip of the punch in a forging station at a stage subsequent to a predetermined forging station for forging and forming a hollow molded product having a hole serving as a pilot hole, the tip is substantially located around the circumference of the through hole at the periphery of the pilot hole. A plurality of cuts are formed radially so as to form a plurality of cuts radially, and a punched hole is formed in the middle of the punch around the prepared hole where the cuts are formed. An eye joint manufacturing apparatus, comprising: a column-shaped punching portion for forming a through hole having a predetermined diameter while dividing a cut-out chip into a plurality of pieces.