Patent Application
20250073767
This application claims priority to Japanese Patent Application No. 2023-144615 filed on Sep. 6, 2023. The disclosure of the above-identified application, including the specification, drawings, and claims, is incorporated by reference herein in its entirety.
The present disclosure relates to an extrusion die for manufacturing a hollow profile having a hollow part, a hollow profile manufactured using this extrusion die, and a manifold.
A pipe manifold to which a plurality of hydrogen tanks is coupled is formed by, for example, an elongated member with an oblong cross-section of which a lateral dimension is longer than a vertical dimension, and has a main pipe hole continuing in a longitudinal direction. Further, a plurality of recessed parts for coupling caps of the hydrogen tanks is formed in an upper surface at regular intervals along the longitudinal direction, and each recessed part and the main pipe hole are communicably connected to each other through a communication hole (branch pipe hole).
When manufacturing a manifold, the main pipe hole is bored by a gun drill in an elongated rod material with a rectangular cross-section along a longitudinal direction, and then the recessed parts and the communication holes (branch pipe holes) are formed.
However, when a long-size elongated rod material is used to manufacture a manifold, the work of boring by a gun drill becomes difficult, which may lead to reduced productivity.
In recent years, therefore, methods have been explored that use extrusion molding to manufacture an elongated rod material (hollow profile) with a hollow part (main pipe hole) for producing a manifold.
As an extrusion die for manufacturing a hollow profile, for example, a hollow die, such as a port-hole die, is used. The port-hole die includes a female die having a die hole that molds an outer peripheral surface of the hollow profile, and a male die having a mandrel that is disposed facing the die hole and molds an inner peripheral surface of the hollow part. Further, the male die has a plurality of port holes formed in an outer circumference of the mandrel along a circumferential direction, and is configured such that the hollow profile is molded as an extrusion material having passed through each port hole passes through a molding gap between an outer peripheral-side bearing part of the die hole and an inner peripheral-side bearing part of the mandrel.
In such a port-hole die, a bridge for supporting the mandrel is provided between each adjacent pair of port holes in the male die. In an ordinary port-hole die, four bridges are disposed at nearly regular intervals in the circumferential direction, and a flow of the extrusion material (extrusion raw material) once diverges at the positions of the bridges and then merges and becomes unified near the molding gap, so that linear marks called weld lines (pressure-bonding lines) are formed in the hollow profile at positions corresponding to the bridges.
For example, in the port-hole die shown in Japanese Unexamined Patent Application Publication No. 2003-71514 (JP 2003-71514 A), weld lines are formed in a rectangular cylindrical hollow profile at middle positions in four surrounding walls (an upper wall, a lower wall, and side walls), and these four weld lines are disposed in a cross shape around a mandrel as the center. In the port-hole dies shown in Japanese Unexamined Patent Application Publication No. 2004-74204 (JP 2004-74204 A) and Japanese Patent No. 3698927, weld lines are formed at four corner portions of each of cylindrical hollow profiles, and these four weld lines are disposed in an X shape around a mandrel as the center.
In the above-described conventional manifold, a circular main pipe hole is formed in an elongated member with a rectangular cross-section along the longitudinal direction, and this main pipe hole is formed on a lower side relative to a middle position in an up-down direction (at a position offset toward a lower surface). In other words, of surrounding walls, a lower surface side is formed thinner and has lower strength compared with an upper surface side and side surface sides. Therefore, if a hollow profile for producing a manifold is molded using the port-hole dies shown in JP 2003-71514 A, JP 2004-74204 A, and Japanese Patent No. 3698927, weld lines are formed on the lower surface side. Thus, a problem arises that sufficient strength as a whole may fail to be secured as the weld lines that cause a decrease in strength are formed on the lower surface side that is thin and has low strength.
The present disclosure has been developed in view of the above-described problem, and an object thereof is to provide a hollow profile-manufacturing extrusion die that can mold a hollow profile having sufficient strength, and further to provide a hollow profile having sufficient strength and a manifold.
A first aspect of the present disclosure is a hollow profile-manufacturing extrusion die. The hollow profile-manufacturing extrusion die manufactures a hollow profile of which, in an outer peripheral surface, a dimension between side surfaces is longer than a dimension between an upper surface and a lower surface, and which has a hollow part continuing in a longitudinal direction on a lower side relative to a middle position in an up-down direction. The hollow profile-manufacturing extrusion die includes a mandrel that molds an inner peripheral surface of the hollow part, and bridges for supporting the mandrel. The mandrel is disposed so as to correspond to a die hole that molds the outer peripheral surface of the hollow profile. The bridges are disposed at positions corresponding to between the hollow part and the side surfaces in the hollow profile, and are not present at positions corresponding to between the hollow part and the lower surface.
According to this configuration, since the bridges are not present on the lower side of the mandrel, a hollow profile in which weld lines are not present on the lower side of the hollow part can be molded. Thus, even though the hollow part in the molded hollow profile is disposed on the lower side, a decrease in strength on the lower side of the hollow part due to formation of weld lines can be prevented, and a hollow profile having sufficient strength can be molded. Although weld lines are formed at side portions of the hollow profile, since the hollow profile has a wide shape thick at the side portions, sufficient strength as a hollow profile can be maintained even when a decrease in strength due to the formation of the weld lines is taken into account.
In the above-described hollow profile-manufacturing extrusion die, the bridges may be disposed only at positions corresponding to a middle part and the side surfaces in the hollow profile.
In the above-described hollow profile-manufacturing extrusion die, a bridge that is disposed at a position corresponding to between one side surface of the side surfaces and the hollow part and a bridge that is disposed at a position corresponding to between the other side surface and the hollow part may be disposed in a straight line as seen from an extrusion direction.
According to this configuration, the above-described effects can be more reliably achieved.
A second aspect of the present disclosure is a hollow profile. The hollow profile is composed of an extruded profile of which, in an outer peripheral surface, a dimension between side surfaces is longer than a dimension between an upper surface and a lower surface, and which has a hollow part continuing in a longitudinal direction on a lower side relative to a middle position in an up-down direction. In the hollow profile, weld lines are formed at positions corresponding to between the hollow part and the side surfaces, and the weld lines are not present at positions corresponding to between the hollow part and the lower surface.
According to this configuration, as with the hollow profile molded by the above-described extrusion die, sufficient strength can be secured.
In the above-described hollow profile, the hollow part may be provided by a circular hole with a diameter of 10 mm or smaller.
In the above-described hollow profile, a dimension from the center of the hollow part to the lower surface may be set to be equal to or smaller than ½ of a dimension from the center of the hollow part to the upper surface.
According to this configuration, the above-described effects can be more reliably achieved.
In a manifold produced using the hollow profile described above, a recessed part may be provided in the upper surface of the hollow profile, and a communication hole communicating with the hollow part may be provided in a bottom wall of the recessed part.
According to this configuration, as with the hollow profile molded by the above-described extrusion die, sufficient strength can be secured.
Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein:
In the hollow profile 1 of this embodiment, to facilitate understanding of the disclosure, four surrounding surfaces constituting the outer peripheral surface 10 are referred to as the upper surface 11, the lower surface 12, and the side surfaces 13. However, these surfaces 11 to 13 are not related to the gravitational direction and may be disposed in whichever directions. For example, when processing or actually using the hollow profile 1, the upper surface 11 may be disposed facing downward or sideways relative to the gravitational direction, or the lower surface 12 may be disposed facing upward or sideways relative to the gravitational direction, or the side surfaces 13 may be disposed facing upward or downward relative to the gravitational direction. (The same applies to the manifold 2 to be described below.)
In this embodiment, when a pressure of high-pressure hydrogen flowing through the hollow profile 1 is taken into account, it is preferable that the diameter of the hollow part 15 be set to 10 mm or smaller as seen in the cross-section of
In this embodiment, it is preferable that, in the hollow profile 1 as seen in the cross-section of
On the other hand, as shown in
As will be described in detail later, weld lines (pressure-bonding lines) 16 that have a linear shape (planar shape) and continue along the longitudinal direction are formed between the hollow part 15 and the side surfaces 13 in the hollow profile 1 and the manifold 2.
As shown in these drawings, the port-hole die 3 of this embodiment includes a male die 4 and a female die 5, and is formed as these dies 4, 5 are combined. In this embodiment, a downstream side in the extrusion direction (a rightward direction in
The female die 5 has a disc shape, and at a center position thereof, a rectangular die hole 51 that increases in diameter toward the front side is formed, and an inner peripheral surface at a back end part of the die hole 51 is formed as a bearing part (outer peripheral-side bearing part) 52. The outer peripheral-side bearing part 52 is a part that molds an outer peripheral surface of the hollow profile 1, and has a rectangular shape with a width dimension longer than an up-down dimension so as to correspond to an outer peripheral shape of the cross-section of the hollow profile 1.
The male die 4 has an annular shape, and at a nearly center part thereof, a through-hole 40 that penetrates in a front-rear direction is formed. Further, in the male die 4, a mandrel 41 extending in the front-rear direction is disposed inside the through-hole 40, and a part of an outer peripheral surface at a leading end part of the mandrel 41 that corresponds to the outer peripheral-side bearing part 52 of the female die 5 is formed as a male-side bearing part 42 (inner peripheral-side bearing part). The inner peripheral-side bearing part 42 is a part that molds the inner peripheral surface of the hollow part 15 of the hollow profile 1, and has a circular cross-section so as to correspond to the cross-sectional shape of the hollow part 15 in the hollow profile 1.
The mandrel 41 is disposed on the lower side relative to a center position in the through-hole 40 of the male die 4 so as to correspond to the hollow part 15 of the hollow profile 1. The mandrel 41 is supported on an inner peripheral surface of the through-hole 40 of the male die 4 through bridges 45. The bridges 45 are disposed along a horizontal direction from side parts of the mandrel 41 toward lateral sides, and are disposed so as to be suspended between the side parts of the mandrel 41 and an inner peripheral-side surface of the through-hole 40 in the male die 4. The bridges 45 on both sides are disposed in a straight line, one on each side of the mandrel 41, as seen in the front view of
In the port-hole die 3 of this embodiment, port holes 46 are formed on the upper side and the lower side of the bridges 45 disposed in a straight line. That is, the port-hole die 3 of this embodiment is a type having two bridges 45 and two port holes 46.
Here, in the port-hole die 3 of this embodiment, the bridges 45 are provided only on both sides of the mandrel 41, and are not present on the lower side of the mandrel 41 nor on the upper side of the mandrel 41. In other words, the bridges 45 are disposed at positions corresponding to between the hollow part 15 and the side surfaces 13 in the hollow profile 1, and are not present at positions corresponding to between the hollow part 15 and the upper surface 11 and positions corresponding to between the hollow part 15 and the lower surface 12 in the hollow profile 1.
The port-hole die 3 having the above-described configuration is set in a container of an extruder to perform extrusion process. In the extrusion process, an extrusion material (metal material), such as aluminum alloy, inside the container flows through the port holes 46 of the male die 4 in a pressurized state. In the process, a flow of the extrusion material once diverges at the positions of the bridge 45, passes through the bridges 45 and merges, and then passes through a molding gap between both bearing parts 42, 52 of the mandrel 41 and the die hole 51, and thereby the outer peripheral surface 10 of the hollow profile 1 and the inner peripheral surface of the hollow part 15 are molded. Thus, the hollow profile 1 is molded. In the hollow profile 1 resulting from this extrusion process, the linear weld lines (pressure-bonding lines) 16 are formed at positions corresponding to the bridges 45, i.e.., from positions on both sides of the inner peripheral surface of the hollow part to the side surfaces 13 of the hollow profile 1.
In this embodiment, the weld lines 16 of the hollow profile 1 are formed only at positions corresponding to between the hollow part 15 and the side surfaces 13, and are not formed at positions corresponding to between the hollow part 15 and the lower surface 12. Therefore, sufficient strength of the hollow profile I can be secured as will be described in detail below.
That is, in the hollow profile 1 for producing the manifold 2 for coupling high-pressure hydrogen tanks as in this embodiment, the hollow part 15 is disposed on the lower side relative to the center position in the up-down direction, so that a portion on the lower side from the hollow part 15 has lower strength compared with portions on both sides of the hollow part 15 or a portion on the upper side of the hollow part 15. In this structure, if weld lines are formed on the lower side of the hollow part 15, a decrease in strength due to the presence of the weld lines serves as another factor that further reduces the strength of the portion of the hollow profile 1 on the lower side of the hollow part 15, making it difficult to sufficiently secure the strength of the profile as a whole.
In this embodiment, therefore, the weld lines 16 are not formed at the portion of the hollow profile 1 on the lower side of the hollow part 15 as already described. Thus, even though the hollow part 15 is formed on the lower side, a decrease in strength due to the weld lines 16 can be prevented, and sufficient strength as the hollow profile 1 can be secured.
In this embodiment, since the weld lines 16 are not formed at the portion of the hollow profile 1 on the upper side of the hollow part 15 either, the strength can be further improved. Specifically, at the upper-side portion of the hollow profile 1, the recessed parts 21 and the communication holes 22 are formed as shown in
In this embodiment, although the weld lines 16 are formed at both side portions of the hollow profile 1, the molded hollow profile 1 is wide and a sufficient plate thickness can be secured at both side portions. Therefore, even when a decrease in strength due to the formation of the weld lines 16 is taken into account, sufficient strength can be secured to such an extent as to pose no problem as the hollow profile 1 for a manifold.
Further, in this embodiment, since the bridges 45 provided on both sides of the mandrel 41 are disposed in a straight line one on each side of the mandrel 41, the mandrel 41 can be supported from both sides in a balanced manner. Thus, the mandrel 41 can be retained with good positional accuracy against the pressure of the flow of the extrusion material, so that the high-accuracy, high-quality hollow profile 1 can be molded.
The hollow profile-manufacturing extrusion die of the present disclosure can be used when molding a hollow profile that is used to produce a manifold for coupling high-pressure hydrogen tanks.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-144615 | Sep 2023 | JP | national |
