JPH068061A - Manufacture of metallic hollow structure body - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing a metallic hollow structure body easy to manufacture and excellent in strength and productivity. CONSTITUTION:At the time of manufacturing a metallic hollow structure body 1 provided with a hollow body part 11 with a slit provided along the longitudinal direction and a solid body part 12 provided on the other side, a mandrel hole 10 is bored to the intermediate part of metallic material along its axial direction by forging, and a mandrel 2 of the approximately same diameter as a hole to be obtained is inserted into the mandrel hole 10. Rolling is then applied to the outer periphery of the mandrel inserted part by a rolling device 3 under heating, and outline machining is applied to the solid body part 12 afterwards.

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 metal hollow structure which is easy to manufacture and has excellent strength and productivity.

[0002]

2. Description of the Related Art As a hollow metal structure, for example, FIG.
There is a rear axle shaft 9 used as an axle as shown in FIG. The rear axle shaft 9 supports the weight of the vehicle body and plays an important role in transmitting the driving force to the wheels 93. Therefore, the rear axle shaft 9
High strength is required. On the other hand, the rear axle shaft 9 is formed with a hollow body portion 91 provided with an elongated hole 90 as shown in FIGS. 14 to 16 in order to reduce the weight of the vehicle. The rear axle shaft 9 is manufactured as follows, as shown in FIGS. 13 to 16.

First, as shown in FIG. 13, an elongated rod-shaped metal material 99 such as carbon steel is used. Next, as shown in FIG. 14, the drill 8 is inserted in the axial direction of the metal material 99.
Use to make a slot 90 with a bottom. Then, FIG.
5, As shown in FIG. 16, in a part of the hollow body portion 91,
The drawn portion 911 is formed by using a swaging machine, a rolling drawing machine, or an extruder (not shown). The throttle portion 911 is provided to increase the axial diameter ratio as it gets closer to the wheel 93 in order to reduce the torsion or bending moment due to the driving torque with respect to the hollow body portion 91.

On the other hand, as shown in FIG. 15, the flange-shaped header portion 92 is manufactured by forging in advance. Then, the header portion 92 is joined to one end of the hollow body portion 91 by friction welding 7. Friction welding 7
The hollow body portion 91 and the header portion 92 to be pressure-welded are brought into pressure contact while rotating at the joint portion 98,
This is a method of joining the two by frictional heat generated on the contact surface.

Thus, as shown in FIG. 16, the rear axle shaft 9 including the hollow body portion 91 and the header portion 92 is manufactured. In addition, the rear axle shaft 9
In manufacturing the metal, as shown in FIG. 14, after making the elongated hole 90 using the drill 8, the end 99 of the metal material 99 is formed.
1 is upset forged to form a header portion 92,
Then, swaging, rolling drawing or cold extrusion may be used.

[0006]

However, the above-mentioned conventional technique has the following problems. That is, as shown in FIG.
When drilling the elongated hole 90 using the drill 8, this drilling operation is generally performed at room temperature. Therefore, it takes a long time,
The work is complicated and expensive. Further, the axis of the elongated hole 90 may be eccentric. Further, as shown in FIG. 15, in the method of friction welding the hollow body portion 91 and the header portion 92,
The joint 98 may be softened and its strength may be reduced.

In addition, defects such as internal voids and cracks are likely to occur in the joint portion 98, and the strength may be reduced. On the other hand, in the method of performing upset forging and cold pressing, the number of steps is large, and the work is complicated, the productivity is lowered, and the cost is increased. The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a method of manufacturing a metal hollow structure which is easy to manufacture and has excellent strength and productivity.

[0008]

According to the present invention, a metal hollow structure having a hollow body portion having elongated holes provided along the length direction and a solid body portion provided on one of the hollow body portions is manufactured. At the same time, forging or drilling the metal material along its axial direction to open a mandrel hole up to the middle of the metal material, then insert a mandrel of approximately the same diameter as the hole to be obtained into the mandrel hole In the above method, the outer periphery of the mandrel insertion part is rolled, swaged or extruded, and then the outer shape is processed to form the solid part, which is a method for producing a hollow metal structure.

What is most noticeable in the present invention is that a metal material thicker than the shaft diameter of the metal material is forged or drilled to form a mandrel hole which is thicker and shallower than the mandrel hole up to the middle, and the mandrel hole is provided with a mandrel. It is to insert and roll the outer periphery of the mandrel insertion part under heating to shape the solid part. In the hollow body portion, half or more of the hollow body portion and the solid body portion are formed in the middle of the metal material, and the hollow body portion is slightly increased. Further, a mandrel having substantially the same shape as the mandrel hole is inserted into the hollow body portion and the outer circumference thereof is rolled.

The mandrel is a mandrel inserted into the elongated hole of the hollow body portion, and holds the shape of the elongated hole so that the mandrel hole does not slip or deform during rolling. As the metal material, for example, structural carbon steel bar or structural alloy steel bar is used. The diameter of the metal material is, for example, 50 to 70 mm.

The length of the metal material is, for example, 30
It is 0 to 1400 mm. These are used, for example, in rear axle shafts and gear shafts of automobiles and industrial vehicles. The diameter of the mandrel hole is, for example, 30
It is preferably ˜50 mm. If it is less than 30 mm, the hole diameter is reduced during rolling, and the effect of weight reduction is poor.
If it exceeds 0 mm, the reduction in hole diameter during rolling will be small,
The strength of the hollow metal structure cannot be obtained. For the rolling, for example, the outer circumference of the mandrel insertion portion is processed under heating at 800 to 1200 ° C. If it is less than 800 ° C, the deformation resistance of the material is high and the rolling load is large, while
If it exceeds 1200 ° C, there is a possibility that a problem of strength reduction due to overheating may occur.

As the processing of the outer circumference of the mandrel hole, for example, swaging (sliding) forming or triaxial roll rolling is used. The swaging method is a method of compressing the metal material in the radial direction while reducing a part or all of the cross section thereof. The above-mentioned three-way axis rolling method is a method of forming a seamless hollow tube (seamless tube) or the like while applying a strong pressure to the rolled end portions of the three rolls (see Fig. 8).

In the outer shape processing, for example, an upsetter forging machine or a friction forging machine is used to form a solid body portion into, for example, a flange-shaped header portion (see FIG. 7). Further, the outer shape processing may be any of cold working, warm working, and hot working. Examples of the hollow metal structure include a rear axle shaft, a gear shaft, and a constant velocity joint intermediate shaft.

[0014]

In the method for manufacturing a metal hollow structure of the present invention, a mandrel hole is formed halfway in the metal material by forging or drilling. Next, a mandrel is inserted into the mandrel hole and heated (for example, 800 to 1200).
The outer circumference of the insertion part is rolled or swaged at a temperature of (° C).

As a result, the metal material between the mandrel and the rolling mill or swaging machine is rolled or forged one after another, so that the hollow portion becomes longer and the wall thickness becomes smaller. In addition, the mandrel should always be held in the part that is being rolled or forged. By the above, a metal hollow structure in which the hollow body portion and the solid body portion are integrally molded can be obtained. Therefore, the manufacture of the metal hollow structure is facilitated, the productivity is improved, and the cost is reduced.

Further, unlike the conventional case, since friction welding is not used, defects such as internal holes and cracks and deterioration of strength due to softening do not occur at the joint portion. Further, since the mandrel hole is formed by forging or drilling, it has a continuous metallographic structure as described above, and further such a structure part is rolled or forged into a long hollow shape as described above. Therefore, the hollow body is formed by a continuous structure and has excellent toughness. Therefore, the strength of the hollow metal structure is improved. As described above, according to the present invention,
It is possible to provide a method for manufacturing a metal hollow structure which is easy to manufacture and has excellent strength and productivity.

[0017]

【Example】

Example 1 A method for manufacturing a metal hollow structure according to an example of the present invention will be described with reference to FIGS. In this example, the rear axle shaft as the metal hollow structure 1 shown in FIG. 7 is manufactured. The metal hollow structure 1 comprises a hollow body portion 11 having elongated holes provided along the longitudinal direction,
It has a solid body portion 12 provided on one side thereof. Further, the solid body portion 12 has a flange-shaped header portion 122.

First, an outline of a method for manufacturing the hollow metal structure 1 will be described. That is, first, as shown in FIGS. 3 and 4, the mandrel hole 10 is formed in the middle of the metal material 19 along the axial direction 190 thereof by forging or drilling. Next, as shown in FIG. 5, as a preliminary step, the mandrel 2 is put into the mandrel hole 10 and is rolled using a pair of upper and lower flat rolls 5. Thereby, in the hollow body portion 11,
A guide portion 111 for gripping during rolling is formed.

Next, in order to carry out rolling according to the present invention,
As shown in FIG. 1, a mandrel 2 having the same diameter as the hole to be obtained is inserted into the mandrel hole 10. Then, the outer circumference 110 of the mandrel insertion portion is rolled under heating. As a result, as shown in FIG. 6, the hollow body portion 1
A metal hollow structure 1 having a mandrel hole 10 and a solid portion 12 is obtained. After that, as shown in FIG.
The solid portion 12 of the hollow metal structure 1 is processed into a header 122.

The metal material 19 is JIS S4.
A rod-shaped object made of 8C material is used. The metal material 19 is
It consists of a round bar with a length of about 450 mm and a diameter of 65 mm. The mandrel hole 10 is drilled by forging or punching at about 1200 ° C. The mandrel hole 10
It is 290 mm deep and has a diameter of 40 mm.

Next, the above manufacturing method will be described in detail. As shown in FIG. 5, the flat roll 5 used in the preliminary step is for making a part of the hollow body portion 11 a little thin in advance before rolling. As a result, the feed roll 4 (Fig. 1)
It is possible to form a guide portion 111 for the.

Next, the hollow body portion 1 of the metal hollow structure 1
In roll-forming 1, rolling is performed by using a rolling device 3 having a triaxial roll as shown in FIGS. As shown in FIGS. 8 to 10, the rolling device 3 has a three-way shaft roll including an upper roll 31 supported by a frame 33, a lower roll 32, and a side roll 33.

As shown in FIGS. 8 and 9, the upper roll 31, the lower roll 32 and the side roll 33 have rolling curved portions 311, 321, 331 near the tip thereof.
Have. Further, each of these rolls has a gear portion 310, 320, 330 at the rear end portion.
The rolling device 3 includes the gear units 310, 320, 330.
And a first gear portion 341 that meshes with each of them. Also,
The first gear portion 341 is connected to a second gear portion 342 that meshes with the first gear portion 341 and a rotating shaft 343 that works together with the second gear portion 342.

The rolling apparatus 3 has an upper drive unit 35 for transmitting power to the second gear unit 342 and the rotating shaft 343.
And a lower drive unit 36. In addition, between both drive parts,
It has a transport pipe portion 37 for transporting the metal material 19. Also,
The transport pipe portion 37 has an insertion opening 370 for the metal material 19 at one end thereof. As shown in FIG. 10, a feed roll 4 for conveying the metal hollow structure 1 in the direction of the arrow is arranged behind the rolling device 3.

Here, as shown in FIGS. 1, 2, and 8 to 10, a mandrel is inserted into the mandrel hole 10 of the metallic hollow structure 1 and, under heating, the upper roll, the lower roll, The outer periphery 110 of the mandrel insertion portion is rolled by the side rolls 31, 32, 33.

That is, as shown in FIG. 1, the mandrel hole 1
The mandrel 2 is put in 0, and the guide portion 111 is pulled while being held by the feed roll 4. In parallel with this, the three-way shaft roll of the rolling device 3 rotates, and rolling is performed while pressing the outer periphery 110 of the hollow body portion 11.

By the above-mentioned rolling, the hollow body portion 11 is formed into an elongated shape, and the mandrel 2 is also pushed out together with this. Therefore, the mandrel 2 is pushed into the hollow body portion 11 and held so that the mandrel 2 is always present in the rolling part of the rolling device 3.

As a result, the metal material 19 as an intermediate product shown in FIG. 6 is obtained. After that, the outer shape of the solid body portion 12 at the rear end portion of the metal material 19 is processed. still,
For the outer shape processing, forging is performed while warm or hot.

As described above, as shown in FIG. 7, the hollow metal body 1 is obtained by integrally molding the hollow body portion 11 and the solid body portion 12 with the flange-shaped header portion 122. The metal hollow structure 1 is used as a rear axle shaft for various automobiles and industrial vehicles. As described above, this rear axle shaft is characterized in that the header portion 122 is formed integrally with one end of the hollow body portion 11 in a continuous state.

Next, the function and effect will be described. In the method for manufacturing the metal hollow structure 1 of this example, as shown in FIG.
Open 0 This makes it possible to form a mandrel hole in which the metal material 19 has a uniform structure, is tenacious, and has a continuous metal structure. Next, as shown in FIGS. 1 and 2, the mandrel 2 is inserted into the mandrel hole 10 and the outer periphery 110 of the inserted portion is rolled under heating.

As a result, the metal material 19 between the mandrel 2 and the rolling device 3 is sequentially rolled, and the hollow body portion 1
1 becomes longer and the thickness becomes smaller. In addition, the mandrel 2 is always held in the rolled portion. By the above, the metal hollow structure 1 in which the hollow body portion and the solid body portion are integrally molded in a continuous state can be obtained.

Therefore, the manufacture of the metal hollow structure 1 is facilitated, the productivity is improved and the cost is reduced. In addition, unlike the conventional method, friction welding is not used, so there is no deterioration of strength due to softening at the joint. Further, since the mandrel hole 10 is formed by forging, it has a continuous metal structure as described above, and such a structure portion is rolled and formed into a long hollow shape as described above.

Further, the hollow body portion 11 is formed of a continuous structure and has excellent toughness. Therefore, the strength of the metallic hollow structure 1 is improved. In addition, since the rolling device 3 is used for rolling, the precision of rolling is improved, and the hollow body portion 11 and the solid body portion 12 can be easily molded integrally.

Embodiment 2 In this embodiment, as shown in FIGS. 11 and 12, instead of the metallic hollow structure 1 of Embodiment 1, a solid body portion 12 is provided in the central portion and both end portions thereof are provided. A metal hollow structure 1A having two hollow body parts 11 and 11 is manufactured. That is, as shown in FIG. 11, first, the hollow body portion 11 on the right side is formed using the rolling apparatus 3 in the same manner as in the first embodiment. Next, the hollow body portion 11 on the left side is similarly molded. As a result, as shown in the figure, a metal hollow structure 1A having a solid body portion 12 at the center and two hollow body portions 11, 11 at both ends thereof is obtained. Others are the same as in the first embodiment.

Next, as shown in FIG. 12, the central portion 121 of the solid body portion 12 is cut by the cutter 5. As a result, it is possible to simultaneously obtain two metal hollow structures 1 as a material for the rear axle shaft from one metal hollow structure 1A. Therefore, according to this example, the metal hollow structure 1A can be obtained with higher productivity and at a lower cost than the first example. In addition, the same effect as that of the first embodiment can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing an initial state of manufacturing a metal hollow structure by a rolling process in Example 1.

FIG. 2 is a perspective view showing a final state of a rolling process in Example 1.

FIG. 3 is a perspective view showing a metal material according to the first embodiment.

FIG. 4 is a perspective view showing a state in which a mandrel hole is formed in a metal material according to the first embodiment.

FIG. 5 is a perspective view showing a state where the guide portion is processed in the first embodiment.

FIG. 6 is a perspective view of a rolled product according to the first embodiment.

FIG. 7 is a perspective view showing a rear axle shaft as a metal hollow structure body according to the first embodiment.

FIG. 8 is a perspective view of a triaxial roll as a rolling device according to the first embodiment.

FIG. 9 is a cross-sectional view of the essential parts of the rolling device in the first embodiment.

FIG. 10 is an explanatory diagram showing a state of rolling processing by the rolling device in the first embodiment.

FIG. 11 is a perspective view showing a state of rolling processing by the rolling apparatus in the second embodiment.

FIG. 12 is a perspective view showing a step of cutting a metal hollow structure according to a second embodiment.

FIG. 13 is a perspective view of a metal material in a conventional method for manufacturing a hollow metal structure.

FIG. 14 is a perspective view showing a punched state in a conventional example.

FIG. 15 is a perspective view showing a joined state of a metal hollow structure in a conventional example.

FIG. 16 is a perspective view of a conventional metal hollow structure.

[Explanation of symbols]

 1. ． ． Metal hollow structure, 10. ． ． Mandrel hole, 11. ． ． Hollow body part, 110. ． ． Outer circumference of mandrel insertion portion, 12. ． ． Solid part, 2. ． ． Mandrel, 3. ． ． Rolling mill, 31. ． ． Upper roll, 32. ． ． Lower roll, 33. ． ． Side rolls,

Claims (1)

[Claims] 1. When manufacturing a metal hollow structure having a hollow body portion having an elongated hole provided along a length direction and a solid body portion provided on one of the hollow body portions, a metal material is used. On the other hand, a mandrel hole is formed halfway in the metal material by forging or drilling along its axial direction, and then a mandrel of approximately the same diameter as the hole to be obtained is inserted into the mandrel hole. Rolling, swaging or extruding around the outer periphery of
A method for manufacturing a metal hollow structure, which comprises performing an outer shape processing for forming a solid portion.