JP2000045767A - Bulge forming die and bulge forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bulge forming die and a bulge forming method by which a pipe bulging rate can be remarkably improved regardless of the shape of both ends pipe parts by increasing a material feeding amount in the forming. SOLUTION: In a bulge forming die where a first pipe hole 5 and a second pipe hole 7 by a diameter of a pipe material 9, are formed at both ends, the pipe bulging holes 6, 8 of large diameter are formed on a central position communicated with both pipe holes 5, 7, and the cylindrical pipe material 9 is pushed into the first pipe hole 5, the pipe bulging holes 6, 8 and the second pipe hole 7 with the internal pressure to form a spindle-shaped pipe having the pipe bulging part on its central part, the bulge forming die comprises the divided type dies 2, 3 divided at the position of the pipe bulging holes 6, 8, and the divided type dies 2, 3 are mounted to a die case 1 relatively movably from a condition that the maximum gap is held in the setting of the preform material to a condition that the gap is closely adhered after the forming termination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of a bulge forming die and a bulge forming method for forming a spindle-shaped pipe used as a component of an exhaust manifold of an automobile.

[0002]

2. Description of the Related Art Conventionally, as a bulge forming die for forming a spindle-shaped pipe, as shown in FIG. 7, a pipe hole having a diameter of a pipe material is provided at both ends, and a large hole is provided at a central position communicating with both pipe holes. There is known an integrated type having a pipe expansion hole having a diameter.

In this conventional bulge forming method using a bulge forming die, both end surfaces of the pipe material are pushed into the expanded hole side while applying an internal pressure to a cylindrical pipe material set through both the pipe hole and the expanded hole. As a result, the material is supplied toward the expansion hole, the internal pressure is further increased, the pipe material is brought into close contact with the inner surface of the expansion hole, and a spindle-shaped pipe having an expansion portion at the center is formed.

[0004]

However, in the above-mentioned conventional bulge forming die and the bulge forming method, since the material is supplied toward the expansion hole while pushing the pipe end faces, the material supply amount by the pushing is reduced. There is a limit, and there is a problem that a spindle-shaped pipe having a high expansion ratio, which is an expansion ratio of the diameter of the expanded portion to the both-ends pipe portion, cannot be formed.

In particular, as shown in FIG. 8, when a pipe hole has a bent shape, even if a pushing force is applied to both end surfaces of the pipe, the flow of the material is poor, and the supply of the material toward the expansion hole is difficult. Since it can hardly be expected, only a spindle-shaped pipe having a low expansion ratio determined by the limit of elongation deformation of the material itself is formed.

That is, in the conventional bulge forming die and the bulge forming method, only a spindle-shaped pipe having a limited expansion ratio can be formed, the degree of freedom in design is low, and the use of the formed product is limited.

The problem to be solved by the present invention is to provide a bulge forming die and a bulge forming method capable of greatly improving the expansion ratio regardless of the shape of the pipe at both ends by increasing the amount of material supplied during molding. Is to do.

[0008]

[Means for Solving the Problems] (Solution 1) A first solution of the above problem (Claim 1) is to provide a first pipe hole and a second pipe hole at both ends according to the diameter of a pipe material, A large-diameter expansion hole is provided at the center position communicating with the hole,
Pushing while applying internal pressure to a cylindrical pipe material set through the first pipe hole, the expansion hole, and the second pipe hole,
In a bulge forming die for forming a spindle-shaped pipe having an expanded portion at the center, a split die is formed at the position of the expanded hole, and the split die is formed from a state where a maximum gap is secured when setting a material before forming. It is characterized in that it is provided on the mold case so as to be relatively movable to the gap close contact state at the end. (Solution 2) The solution 2 of the above-mentioned problem (Claim 2) is:
2. The bulge mold according to claim 1, wherein said first pipe hole and said second pipe hole are bent. (Solution Means 3) Solution Means 3 (Claim 3) of the above problem is:
The bulge mold according to claim 1 or 2,
The split mold is characterized in that it has a two-split configuration of a first split mold and a second split mold in which a dividing gap is set at a substantially central position of the pipe expansion hole. (Solution 4) The solution 4 of the above problem (Claim 4) is:
The bulge mold according to claim 1 or 2,
The split mold is characterized in that the split mold has a three-split configuration including a first split mold, a second split mold, and a third split mold in which the positions of both ends of the pipe expansion hole are divided gaps. (Solution 5) The solution 5 of the above-mentioned problem (Claim 5) is:
The bulge mold according to claim 1, wherein
A spring for applying a biasing force in a direction to open the gap is interposed at the divided gap position of each of the divided dies. (Solution 6) A solution 6 of the above problem (Claim 6) is:
Using a split mold divided at the position of the expansion pipe hole, the inner pipe is pushed through while applying internal pressure to the cylindrical pipe material set through the first pipe hole, the expansion pipe hole, and the second pipe hole, and the expansion pipe section is formed at the center. A bulge forming method for forming a spindle-shaped pipe having a maximum gap between each of the split dies, wherein a pipe central portion is formed in a cylindrical pipe material set in a first pipe hole, an expanded pipe hole, and a second pipe hole. A first step of applying an internal pressure to the extent that it begins to swell, a second step of pushing the split mold so as to reduce the gap in accordance with the swelling state of the pipe central part by controlling the internal pressure, And forming a spindle-shaped pipe having an expanded portion by bringing the central portion of the pipe into close contact with a split-type expanded hole. (Solution 7) The solution 7 of the above-mentioned problem (Claim 7) is:
A spindle-shaped pipe formed by the bulge forming method according to claim 6 is divided from a center position of the expanded portion and applied as two components of an exhaust manifold of an automobile equipped with a multi-cylinder engine.

[0009]

(Embodiment 1) Embodiment 1 is a bulge forming die and a bulge forming method according to the first, second, third, fifth, sixth and seventh aspects of the present invention. [Regarding Bulge Mold] FIG. 1A shows a bulge mold according to the first embodiment, wherein 1 is a mold case, 2 is a first split mold, 3 is a second split mold, 4 is a spring, and 5 is a spring. A first pipe hole, 6 is a first expansion hole, 7 is a second pipe hole, 8 is a second expansion hole, 9 is a pipe material, 10 is a first plug, and 11 is a second plug.

The bulge forming die has a first pipe hole 5 and a second pipe hole 7 at both ends depending on the diameter of the pipe material 9.
Large-diameter pipe expansion holes 6 and 8 are provided at central positions communicating with both pipe holes 5 and 7, and are set so as to penetrate the first pipe hole 5, the pipe expansion holes 6 and 8, and the second pipe hole 7. As shown in FIG. 2, this is a mold for forming a spindle-shaped pipe 12 having bent pipe portions 12a and 12b at both ends and an expanded portion 12c at the center as shown in FIG.

In the bulge forming die of the first embodiment, the first part is obtained by dividing the pipe expansion holes 6 and 8 into two at a substantially central position as a division gap.
It is composed of a split mold 2 and a second split mold 3, and both split molds 2, 3
With the maximum clearance when setting the material before molding (Fig. 1
It is provided to the mold case 1 so as to be relatively movable from (a)) to the gap close contact state at the end of molding (FIG. 1 (c)). The first pipe hole 5 and the second pipe hole 7 are bent. In addition, the first split mold 2 and the second split mold 3
A spring 4 for applying an urging force in a direction to open the gap is interposed at the divided gap position.

Therefore, the material is supplied to the pipe expansion holes 6 and 8 by pushing the split dies 2 and 3 irrespective of the quality of the material flow.
The pipe material for the maximum gap is secured as the material supply amount to the expansion holes 6 and 8, and the pipe expansion compared with the conventional pipe end pressing in which not only the pushing amount but also the good material flow is required. The material supply to the holes increases.

By increasing the amount of material supplied to the tube expansion holes 6 and 8, it is possible to provide a bulge forming die capable of greatly improving the tube expansion ratio of the tube expansion portion 12c.

A first pipe hole 5 and a second pipe hole 7
Has a bent shape. However, in securing the amount of material supplied to the expansion holes 6 and 8, the quality of the material flow does not matter, and therefore, the bent pipe holes 5 and 7 are used. Even in this case, a high expansion ratio can be secured.

Further, since a spring 4 for applying an urging force in a direction to open the gap is interposed at the divided gap position between the first divided mold 2 and the second divided mold 3, the operation of the divided molds 2 and 3 is performed. Control can be performed by a simple pushing force control applied to the split dies 2 and 3. [About bulge forming method]
1A to 1C are views showing a bulge forming method according to the first embodiment.

The bulge forming method includes a first split mold 2 and a second split mold 2 which are divided into two at substantially the center positions of the pipe expansion holes 6 and 8 as a division gap.
Using the split mold 3, the first pipe hole 5, the expansion holes 6, 8 and the second
A cylindrical pipe material 9 set through the pipe hole 7
As shown in FIG. 2, a spindle-shaped pipe 12 having bent pipe portions 12a and 12b at both ends and an expanded portion 12c at the center as shown in FIG.

In the first step shown in FIG. 1 (a), the first pipe hole 5
Then, an internal pressure is applied to the cylindrical pipe material 9 set in the pipe expansion holes 6 and 8 and the second pipe hole 7 to such an extent that the central portion of the pipe starts to expand by the supply of hydraulic pressure from one or both of the plugs 10 and 11.

In the second step shown in FIG. 1B, the two split molds 2 and 3 are connected to both plugs 1 and 2 so as to reduce the gap in accordance with the bulging state of the center of the pipe by controlling the internal pressure.
It is pushed in by the pushing force applied to 0,11. In other words, the control of the pushing operation of the two split dies 2 and 3 is performed by maintaining the opening of the split dies 2 and 3 by the urging force of the spring 4 and applying the pushing force corresponding to the magnitude and time of the internal pressure to both plugs 10 and 3. This is done by adding to 11.

In the third step shown in FIG. 1C, the gaps between the two split dies 2 and 3 are brought into close contact with each other, and the internal pressure is increased so that the center of the pipe is inserted into the expansion holes 6 and 8 of the two split dies 2 and 3. The spindle-shaped pipe 12 having the expanded portion 12c is formed in close contact therewith.

Therefore, as described above, the material is supplied to the pipe expansion holes 6 and 8 by the method of pushing the split dies 2 and 3, and the pipe material for the maximum gap between the split dies 2 and 3 is expanded at the time of bulge forming. The amount of material supplied to the holes 6 and 8 is secured.

By increasing the amount of material supplied to the pipe expansion holes 6 and 8, it is possible to provide a bulge forming method capable of greatly improving the pipe expansion rate of the pipe expansion section 12c regardless of the shape of the pipe sections at both ends. [Application to Exhaust Manifold] FIG. 2A is a view showing a spindle type pipe formed by the bulge forming method of the first embodiment, and FIG. 2B is a view showing application of the spindle type pipe to the exhaust manifold.

As shown in FIG. 2A, the application to the exhaust manifold is divided into two from the center of the expanded portion 12c of the spindle-shaped pipe 12, and as shown in FIG. The exhaust tube 14 is attached to the two components 12 'and 12' of the exhaust manifold of the vehicle equipped with the exhaust valve 13 and the two components 12 'and 12', respectively.
Is applied.

Therefore, the bulge-formed spindle-shaped pipe 1
2 to which a lightweight and inexpensive automobile exhaust manifold can be provided. (Embodiment 2) A bulge forming die and a bulge forming method according to Embodiment 2 corresponding to the first, fourth, fifth and sixth aspects of the present invention will be described.

FIG. 3 is a cross-sectional view showing a bulge forming die and a first step of the bulge forming method according to the second embodiment. FIG. 4 is a side view showing the bulge forming die according to the second embodiment. 2
FIG. 20 is a cross-sectional view showing a second step and a third step of the bulge forming method, wherein 20 is a mold case, 21 is a first split mold, 22 is a second split mold, 23 is a second split mold, 24 is a first spring, 25
Is a second spring, 26 is a first pipe hole, 27 is an expansion hole, 28 is a second pipe hole, 29 is a pipe material, 30 is a first plug, and 31 is a second plug.

In the bulge forming die of the second embodiment, the split die is a first split die 21, a second split die 22, and a third split die 23, each of which is divided into three by using the positions of both ends of the expansion hole 27 as a split gap.
, And both pipe holes 26 and 28 are short straight tubular holes. The other configuration is the same as that of the first embodiment, and the description is omitted.

In the bulge forming method according to the second embodiment, the cylinders set in the first pipe hole 26, the expanded pipe hole 27, and the second pipe hole 28 with the maximum clearance between the split dies 21, 22, 23 secured. A first step (FIG. 3) of applying an internal pressure to the pipe material 29 to such an extent that the central portion of the pipe starts to swell, and a first split mold 21 for reducing the gap in accordance with the swelling state of the central portion of the pipe by controlling the internal pressure. The second step (upper half in FIG. 4) of pushing the three-piece mold 23 toward the second mold 22 and the gaps between the two molds 21, 22 and 23 are brought into close contact with each other, and the inner pressure is increased so that the center of the pipe is removed. After a third step (lower half in FIG. 4) of bringing the pipe into close contact with the expansion hole 27 of the two-piece mold 22, a spindle-shaped pipe 32 having an expansion part is formed.

Therefore, in the second embodiment, since the second split mold 22 is set at the position to be the expanded portion, the spindle-shaped pipe 32 having the cylindrical expanded portion without unevenness can be formed. That is, since the pipe material 29 has the property of expanding from the central portion when an internal pressure is applied, the expanded portion can be made cylindrical by setting the second split mold 22 at the central portion. (Other Embodiments) In the second embodiment, the split type
An example is shown in which the pipe hole is a short straight tubular hole with a split configuration. However, as shown in FIG. 6 (a), the split mold is formed into a three-piece configuration, and the pipe holes 26 ', 26 with bent pipe holes are formed. '. Further, as shown in FIG.
An example in which the division type is a multi-division configuration such as a four-division configuration may be used. However, in the case of multi-segmentation, the operation of the split mold is controlled so that it starts closing at the center of the split mold formed at the time of pushing and gradually closes the outer gap.

In the first and second embodiments, an example has been described in which the split-type operation control is performed by a spring and a pushing force.
Even if a spring is not used, the operation of each of the split dies may be independently controlled, or the operation of each of the split dies may be controlled in conjunction with each other.

[0029]

According to the first aspect of the present invention, a first pipe hole and a second pipe hole are provided at both ends according to the diameter of a pipe material, and a large-diameter pipe is provided at a central position communicating with both pipe holes. A bulge for forming a spindle-shaped pipe having a pipe expansion hole provided with an internal pressure and applying an internal pressure to a cylindrical pipe material set through the first pipe hole, the pipe expansion hole, and the second pipe hole while applying internal pressure. In the molding die, it is composed of a divided die divided at the position of the pipe expansion hole, and the divided die is relatively movable from the state where the maximum gap is secured at the time of setting the material before molding to the close contact state at the end of molding. The bulge forming die can provide a bulge forming die capable of greatly improving the expansion ratio regardless of the shape of the pipes at both ends due to an increase in the amount of material supplied at the time of forming.

According to the second aspect of the present invention, the first aspect is provided.
In the bulge forming die described in the above, the first pipe hole and the second pipe hole have a bent shape, so that in addition to the effect of the invention according to the first aspect, bent pipe portions are provided at both ends and expanded at the center. A spindle-shaped pipe having a high-efficiency expanded portion can be formed.

According to the third aspect of the present invention, there is provided the first aspect.
Alternatively, in the bulge forming die according to the second aspect, the split die has a two-division configuration of a first split die and a second split die having a split gap substantially at the center position of the pipe expansion hole. In addition to the effects of the invention, a spindle-shaped pipe having an expanded portion with a high expansion ratio at the center can be formed with the simplest split type structure.

According to the fourth aspect of the present invention, there is provided the first aspect.
3. The bulge forming die according to claim 2, wherein the split die is divided into three first portions each having a position at both ends of the expansion hole.
Since the split type, the second split type, and the third split type have a three-segment configuration, in addition to the effects of the invention described in claim 1 or 2, a spindle-shaped pipe having a cylindrical expanded portion with no unevenness in the center portion is provided. Can be molded.

According to the invention of claim 5, claim 1 is
In the bulge forming die according to the fourth aspect, a spring for applying a biasing force in a direction to open the gap is interposed at the divided gap position of each divided mold, so that the bulge forming die is arranged.
In addition to the effects of the described invention, the split-type operation control can be easily performed only by the pushing force or the pushing stroke.

[0034] In the invention according to claim 6, a cylindrical pipe set through the first pipe hole, the expansion pipe hole, and the second pipe hole using a split mold divided at the position of the expansion pipe hole. A bulge forming method for forming a spindle-shaped pipe having an expanded portion at a central portion by applying pressure while applying an internal pressure to a material, wherein a first pipe hole, an expanded hole, and a second pipe are formed in a state in which a maximum clearance of each split mold is secured. The first step of applying an internal pressure to the cylindrical pipe material set in the hole so that the central part of the pipe starts to expand, and the split mold is pushed in so as to reduce the gap according to the state of expansion of the central part of the pipe by controlling the internal pressure. A second step and a third step of forming a spindle-shaped pipe having an expanded portion by closely contacting the gaps of the split molds, increasing the internal pressure, and bringing the pipe central portion into close contact with the expansion holes of the split molds, During molding The increased charge supply amount, can provide a bulge forming method of obtaining substantially improved expansion ratio regardless of the both end pipe portion shape.

In the invention according to claim 7, claim 6
The spindle-shaped pipe formed by the bulge forming method described above is divided from the center of the expanded portion and applied as two components of an exhaust manifold of an automobile equipped with a multi-cylinder engine. In addition, it is possible to provide a lightweight and inexpensive automobile exhaust manifold to which a spindle-shaped pipe formed by bulge molding is applied.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a bulge forming die and a bulge forming method according to a first embodiment.

FIG. 2 is a diagram showing a state in which a spindle-shaped pipe manufactured by the bulge forming method according to the first embodiment is applied to an exhaust manifold of an automobile.

FIG. 3 is a sectional view showing a first step of a bulge forming die and a bulge forming method according to a second embodiment.

FIG. 4 is a side view showing a bulge forming die according to a second embodiment.

FIG. 5 is a sectional view showing a second step and a third step of the bulge forming method according to the second embodiment. FIG. 5 is a view showing a bulge forming die and a bulge forming method according to the first embodiment.

FIG. 6A is a cross-sectional view showing a bulge forming die according to an embodiment of a three-piece bent pipe, and FIG. 6B is a cross-sectional view showing a bulge forming die according to an embodiment of a four-piece bent pipe. FIG.

FIG. 7 is a view showing a conventional bulge forming die and a bulge forming method.

FIG. 8 is a view showing a conventional bulge forming die having a bent pipe and a bulge forming method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold case 2 1st split type 3 2nd split type 4 Spring 5 1st pipe hole 6 1st expansion hole 7 2nd pipe hole 8 2nd expansion hole 9 Pipe material 10 1st plug 11 2nd plug 12 Spindle type pipe 12a , 12b bent pipe section 12c

Claims (7)

[Claims] 1. A first pipe hole depending on the diameter of a pipe material (9).
(5) and a second pipe hole (7) are provided at both ends, and a large-diameter expansion hole (6) is provided at a central position communicating with both pipe holes (5) and (7).
, (8) are provided, the first pipe hole (5) and the expansion hole (6),
(8) and through the second pipe hole (7), press into the set cylindrical pipe material (9) while applying internal pressure to form a spindle-shaped pipe (12) having an expanded part (12c) in the center. In the bulge forming die, a split die (2) divided at the positions of the pipe expansion holes (6) and (8),
The split molds (2) and (3) can be moved relative to the mold case (1) from the state where the maximum gap is secured when setting the material before molding to the state where the gap is in close contact at the end of molding. A bulge forming die characterized by being provided. 2. A bulge forming die according to claim 1, wherein said first pipe hole (5) and said second pipe hole (7) are bent. 3. A bulge forming die according to claim 1, wherein said split die has a first split die (2) having a split center at a substantially central position of the pipe expansion holes (6) and (8). A bulge forming die characterized by having a two-part structure using a second split mold (3). 4. The bulge forming die according to claim 1, wherein the split die has a first split die (21) and a second split die that are divided into three at both end positions of an expansion hole (27). A bulge forming die characterized by having a three-part structure including a split mold (22) and a third split mold (23). 5. A bulge forming die according to claim 1, wherein a spring for applying a biasing force in a direction to open the gap at a position of the divided gap of each of the divided dies. A bulge forming die characterized by interposing. 6. A first pipe hole (5) and a pipe expansion hole (6) using split molds (2) and (3) divided at positions of the pipe expansion holes (6) and (8).
, (8) and the second pipe hole (7) are pushed into the set cylindrical pipe material (9) while applying internal pressure, and the spindle type pipe (12) having the expanded part (12c) in the center is inserted. A bulge forming method for forming, wherein a maximum gap between each of the split molds (2) and (3) is secured, and
A first step of applying an internal pressure to the cylindrical pipe material (9) set in the pipe hole (5), the expansion hole (6), (8) and the second pipe hole (7) such that the center of the pipe starts to expand; The second step of pushing the split molds (2) and (3) to reduce the gap in accordance with the bulging state of the pipe center part by controlling the internal pressure, and the gap between the split molds (2) and (3) is closely adhered. The inner pressure is increased and the center of the pipe is brought into close contact with the expansion holes (6) and (8) of the split molds (2) and (3) to form a spindle-shaped pipe (12) having an expansion part (12c). A bulge forming method, comprising the steps of: 7. An exhaust manifold for an automobile equipped with a multi-cylinder engine (13), wherein a spindle-shaped pipe (12) formed by the bulge forming method according to claim 6 is divided from a center position of an expanded portion (12c). A bulge forming method characterized by being applied as two components (12 ') and (12').