The contents of Japanese Patent Application No. 2019-039830, and of International Patent Application No. PCT/JP2020/004985, on the basis of each of which priority benefits are claimed in an accompanying application data sheet, are in their entirety incorporated herein by reference.
A certain embodiment of the present invention relates to a metal pipe forming method, a metal pipe, and a forming system.
In the related art, a forming apparatus for forming a metal pipe including a pipe portion and a flange portion by supplying a gas into a heated metal pipe material and expanding the material is known. For example, the related art discloses a forming apparatus including: upper and lower dies to be paired with each other; a gas supply portion that supplies a gas into a metal pipe material held between the upper and lower dies; a heating mechanism that heats the metal pipe material; and a cavity portion formed by combining the upper and lower dies.
According to an embodiment of the present disclosure, there is provided a metal pipe forming method including: disposing a metal pipe material having a hollow shape between a pair of dies; and forming a metal pipe including a pipe portion and a flange portion by expanding the metal pipe material by supplying a fluid and bringing the metal pipe material into contact with the pair of dies. In the forming of the metal pipe, a gap which is positioned between a pair of inner surfaces of the flange portion and communicates with an internal space of the pipe portion is formed, and the flange portion is provided with a through-hole connected to the gap.
According to another embodiment of the present disclosure, there is provided a metal pipe including: a pipe portion having a hollow shape; and a flange portion integrated with the pipe portion. The flange portion has a pair of inner surfaces and a through-hole, a gap that communicates with an internal space of the pipe portion is positioned between the pair of inner surfaces, and the through-hole is connected to the gap.
According to still another embodiment of the present disclosure, there is provided a metal pipe forming system including: a forming unit that forms a metal pipe including a pipe portion and a flange portion by disposing a metal pipe material having a hollow shape between a pair of dies, expanding the metal pipe material by supplying a fluid, and bringing the metal pipe material into contact with the pair of dies; and a processing unit that provides a through-hole in the metal pipe, in which the forming unit forms a gap which is positioned between a pair of inner surfaces of the flange portion and communicates with an internal space of the pipe portion, and the processing unit provides a through-hole connected to the gap in the flange portion.
A metal pipe formed by using the forming apparatus shown in the related art exhibits a seamless hollow shape. In a case where a liquid such as water has entered such a metal pipe, the liquid is less likely to be discharged from the metal pipe. Therefore, rust may occur on the metal pipe in which the liquid is collected. Therefore, countermeasures against rust on the metal pipe as described above are required.
It is desirable to provide a metal pipe forming method, a metal pipe, and a forming system capable of suppressing the generation of rust.
According to the metal pipe forming method, in the forming of the metal pipe, a gap which is positioned between the pair of inner surfaces of the flange portion and communicates with an internal space of the pipe portion is formed. The flange portion is provided with a through-hole connected to the gap. Accordingly, for example, even in a case where a liquid such as water has entered the internal space of the pipe portion, the liquid can be easily discharged through the gap and the through-hole. Thereby, the liquid is less likely to be collected inside the metal pipe, and thus, the generation of rust on the metal pipe can be suppressed.
In the forming of the metal pipe, a plurality of the gaps which are positioned between the pair of inner surfaces and intermittently disposed along an axial direction of the pipe portion may be formed, and the pair of inner surfaces may be in close contact with each other between the gaps adjacent to each other along the axial direction. In this case, a portion where the pair of inner surfaces are in close contact with each other, and another member can be spot-welded. In addition, by the formation of the plurality of gaps inside the flange portion, the liquid is less likely to be collected in the internal space of the pipe portion. Therefore, it is possible to suppress the occurrence of intensity deterioration of the pipe portion, which is the main body of the metal pipe.
The flange portion may be provided with the through-hole for each of the plurality of gaps. In this case, it is possible to excellently suppress the collection of liquid inside the metal pipe.
The gap may be continuously provided along the axial direction of the pipe portion, and the pair of inner surfaces maybe partially in close contact with each other. In this case, the part where the pair of inner surfaces are in close contact with each other and another member can be spot-welded. Even in a case where the number of through-holes formed in the flange portion is reduced, the liquid can be excellently discharged through the gap and the through-hole.
In this metal pipe, the gap that communicates with the internal space of the pipe portion is positioned between the pair of inner surfaces of the flange portion. The through-hole is connected to the gap. Accordingly, for example, even in a case where a liquid such as water has entered the internal space of the pipe portion, the liquid can be easily discharged through the gap and the through-hole. Thereby, the liquid is less likely to be collected inside the metal pipe, and thus, the generation of rust on the metal pipe can be suppressed.
According to the forming system, it is possible to obtain the action and effects having the same meaning as those of the above-described forming method.
Hereinafter, a preferred embodiment of a metal pipe according to an aspect of the present disclosure, a forming method thereof, and a forming system will be described with reference to the drawings. In addition, in each drawing, the same reference numerals are assigned to the same portions or the corresponding portions, and repeated descriptions thereof are omitted.
The metal pipe 1 includes a pipe portion 100 and flange portions 101 and 102. The pipe portion 100 is a main body having a hollow shape, and has, for example, a substantially square cross section. An internal space S1 is defined by an inner peripheral surface 100a of the pipe portion 100. In the present embodiment, each of the inner peripheral surface 100a and the outer peripheral surface 100b of the pipe portion 100 has a planar shape, but the present disclosure is not limited thereto. From the viewpoint of improvement of withstanding intensity, irregularities or the like maybe appropriately provided in the pipe portion 100.
The flange portion 101 is a protrusion portion that protrudes from the pipe portion 100 along the transverse direction Y. The flange portion 101 is provided along the longitudinal direction X. In the present embodiment, the dimension of the flange portion 101 in the longitudinal direction X is substantially the same as the dimension of the pipe portion 100 in the longitudinal direction X. The flange portion 101 is formed by folding a portion that protrudes from the pipe portion 100. Therefore, the flange portion 101 and the pipe portion 100 are seamlessly integrated with each other. From the viewpoint of welding and the like, the protrusion amount of the flange portion 101 is, for example, 1 mm or more and 100 mm or less. The tip of the flange portion 101 is rounded, but the present disclosure is not limited thereto.
The flange portion 102 is a protrusion portion that protrudes from the pipe portion 100 along the transverse direction Y, and is provided on the opposite side of the flange portion 101 through the pipe portion 100 in the transverse direction Y. Similar to the flange portion 101, the flange portion 102 is provided along the longitudinal direction X. The flange portion 102 is also formed by folding a portion that protrudes from the pipe portion 100. Therefore, the flange portion 102 and the pipe portion 100 are seamlessly integrated with each other. From the viewpoint of welding and the like, the protrusion amount of the flange portion 102 is, for example, 1 mm or more and 100 mm or less. The tip of the flange portion 102 is rounded, but the present disclosure is not limited thereto.
As shown in
As shown in
The regions R1 and R2 are provided alternately with each other in the longitudinal direction X. Therefore, a plurality of gaps S2 are formed in the metal pipe 1, and the plurality of gaps S2 are intermittently disposed along the longitudinal direction X. Of the dimensions of the metal pipe 1 in the longitudinal direction X, a ratio of the dimensions of the region R1 in the longitudinal direction X is, for example 90% or less. Of the dimensions of the metal pipe 1 in the longitudinal direction X, a ratio of the dimensions of the region R2 in the longitudinal direction X is, for example 10% or more and 50% or less.
As shown in
In the present embodiment, the through-hole 110 is provided at the tip of the flange portion 102, but the present disclosure is not limited thereto. The through-hole 110 may be provided at the lowermost location (that is, the location where the liquid is most likely to be collected) in the flange portion 102. Therefore, for example, in a case where the flange portion 102 in the metal pipe 1 is positioned at the lowermost, the through-hole 110 may be provided at the most protruding portion in the flange portion 102. The shape of the flange portion 102 may be adjusted so that the liquid can easily reach the through-hole 110. For example, the inner surfaces 102a, 102b, and the like of the flange portion 102 may be bent, or the inner surfaces 102a, 102b, and the like may be provided with a gradient .
Next, a forming method of the metal pipe 1 according to the present embodiment will be described with reference to
The forming die 13 is a die used for forming the metal pipe material 14 into the metal pipe. Therefore, each of the lower die 11 and the upper die 12 included in the forming die 13 is provided with a cavity (recessed part) in which the metal pipe material 14 is accommodated (details thereof will be described later).
The lower die 11 is fixed to a large base stage 15. The lower die 11 is configured with a large steel block and includes a cavity 16 on an upper surface of the lower die 11, for example. A cooling water passage 19 is formed in the lower die 11. Further, the lower die 11 includes a thermocouple 21 inserted from below substantially at the center. The thermocouple 21 is supported to be movable upward or downward by a spring 22. The thermocouple 21 is merely an example of temperature measurement means, and may be a non-contact type temperature sensor such as a radiation thermometer or an optical thermometer. When the correlation between the energization time and the temperature can be obtained, the temperature measurement means may be omitted.
An electrode storage space 11a is provided in the vicinity of the left and right ends (left and right ends in
On the upper surface of the lower electrodes 17 and 18, semi-arc-shaped concave grooves 17a and 18a corresponding to the outer peripheral surface on the lower side of the metal pipe material 14 are respectively formed (refer to
The upper die 12 is configured with a large steel block similar to the lower die 11, and is fixed to a slide 81 (details thereof will be described later) that configures the drive mechanism 80. A cavity 24 is formed on the lower surface of the upper die 12. The cavity 24 is provided at a position facing the cavity 16 of the lower die 11. A cooling water passage 25 is provided inside the upper die 12.
Similar to the lower die 11, an electrode storage space 12a is provided in the vicinity of the left and right ends (left and right ends in
On the lower surface of the upper electrodes 17 and 18, the semi-arc-shaped concave grooves 17a and 18a corresponding to the outer peripheral surface on the upper side of the metal pipe material 14 are respectively formed (refer to
On the upper surface of the lower die 11, when the surface of the cavity 16 at the center of the lower die 11 is defined as a reference line LV2, the step is formed by a first protrusion 11b, a second protrusion 11c, a third protrusion 11d, and a fourth protrusion 11e. The first protrusion lib and the second protrusion 11c are formed on the right side (the right side in
As shown in
As shown in
The first protrusion 12b of the upper die 12 faces the first protrusion 11b of the lower die 11, the second protrusion 12c and the fifth protrusion 12f of the upper die 12 face the second protrusion 11c of the lower die 11, the cavity 24 of the upper die 12 faces the cavity 16 of the lower die 11, the third protrusion 12d of the upper die 12 faces the third protrusion 11d of the lower die 11, and the fourth protrusion 12e of the upper die 12 faces the fourth protrusion 11e of the lower die 11. Accordingly, a space is formed when the upper die 12 and the lower die 11 are fitted respectively between the second protrusion 12c and the fifth protrusion 12f of the upper die 12 and the second protrusion 11c of the lower die 11 and between the third protrusion 12d of the upper die 12 and the third protrusion 11d of the lower die 11. A space is formed when the upper die 12 and the lower die 11 are fitted between the cavity 24 of the upper die 12 and the cavity 16 of the lower die 11.
Returning to
The heating mechanism (power supply portion) 50 includes a power supply source 55 and a power supply line 52 which electrically connects the power supply source 55 and the electrodes 17 and 18 to each other. The power supply source 55 includes a DC power source and a switch, and can energize the metal pipe material 14 through the power supply line 52 and the electrodes 17 and 18. In the present embodiment, the power supply line 52 is connected to the lower electrodes 17 and 18, but the present disclosure is not limited thereto. The controller 70 can control the heating mechanism 50 such that the metal pipe material 14 is heated to a quenching temperature (for example, equal to or higher than an AC3 transformation point temperature) .
Each of the pair of gas supply portions 40 includes a cylinder unit 42 that is placed and fixed on the base stage 15 through a block 41, a cylinder rod 43 that advances and retreats in accordance with the operation of the cylinder unit 42, and a gas supply nozzle 44 connected to the tip of the cylinder rod 43. The cylinder unit 42 is a portion that drives the gas supply nozzle 44 to advance and retreat with respect to the metal pipe material 14 through the cylinder rod 43. The gas supply nozzle 44 is a portion configured to be capable of communicating with the inside of the metal pipe material 14 held by the pipe holding mechanism 30, and supplies a gas for expansion forming to the inside. The gas supply nozzle 44 includes a tapered surface 45 provided so that the tip thereof is tapered, a gas passage 46 provided on the inside thereof, and an on-off valve 47 positioned at the outlet of the gas passage 46. The tapered surface 45 is formed in a shape that can be exactly fitted to and in contact with the tapered concave surfaces 17b and 18b of the electrodes 17 and 18 (refer to
The gas supply unit 60 includes the gas source 61, an accumulator (gas storage unit) 62 in which the gas supplied by the gas source 61 is stored, a first tube 63 which extends from the accumulator 62 to the cylinder unit 42 of the gas supply portion 40, a pressure control valve 64 and a switching valve 65 which are provided in the first tube 63, the second tube (pipe) 67 which extends from the accumulator 62 to the gas supply nozzle 44 of the gas supply portion 40, and a pressure control valve 68 and a check valve 69 which are provided in the second tube 67. The pressure control valve 64 plays a role of supplying a gas, which has an operation pressure applied to a pressing force against the metal pipe material 14 of the gas supply nozzle 44, to the cylinder unit 42. The check valve 69 plays a role of preventing the gas from backflowing in the second tube 67.
The pressure control valve 68 is a valve that adjusts the pressure in the second tube 67 under the control of the controller 70. For example, the pressure control valve 68 plays a role of supplying a gas (hereinafter, referred to as low-pressure gas) having an operation pressure (hereinafter, referred to as first ultimate pressure) for temporarily expanding the metal pipe material 14, and a gas (hereinafter, referred to as high-pressure gas) having an operation pressure (hereinafter, referred to as second ultimate pressure) for forming the metal pipe, into the second tube 67. Accordingly, the low-pressure gas and the high-pressure gas can be supplied to the gas supply nozzle 44 connected to the second tube 67. The pressure of the high-pressure gas is, for example, approximately 2 to 5 times that of the low-pressure gas.
With the information transmitted from (A) shown in
Next, an example of the forming method of the metal pipe 1 using the forming apparatus 10 will be described with reference to
Next, as shown in
Next, as shown in
When the flange portion 102 is formed, the portion that has entered between the second protrusion 11c and the fifth protrusion 12f in the expanded metal pipe material 14 is formed following the shapes of only the first protrusion 12b, the second protrusion 11c, and the fifth protrusion 12f, as shown in
The outer peripheral surface of the blow-formed and expanded metal pipe material 14 comes into contact with the lower die 11 and the upper die 12 and is rapidly cooled. Accordingly, the metal pipe material 14 is quenched. The upper die 12 and the lower die 11 have a large heat capacity and are managed at a low temperature. Therefore, the heat of the pipe surface is rapidly taken to the die side as the metal pipe material 14 comes into contact with the upper die 12 and the lower die 11. The above-described cooling method is referred to as die contact cooling or die cooling. Immediately after being rapidly cooled, austenite transforms into martensite (hereinafter, transformation from austenite to martensite is referred to as martensitic transformation). The cooling speed is set to be low in a second half of the cooling, and thus, martensite transforms into another structure (such as troostite, sorbite, or the like) due to recuperation. Therefore, it is not necessary to separately perform tempering treatment. In the present embodiment, the cooling may be performed by supplying a cooling medium into, for example, the cavities 16 and 24, instead of or in addition to the die cooling. For example, cooling may be performed by bringing the metal pipe material 14 into contact with the dies (the upper die 12 and the lower die 11) until a temperature at which the martensitic transformation starts is reached, and the dies may be opened thereafter with a cooling medium (cooling gas) blown onto the metal pipe material 14 such that martensitic transformation occurs.
After the metal pipe 1 is formed, the metal pipe 1 is carried out from the forming apparatus 10. For example, the metal pipe 1 is carried out from the forming apparatus 10 by using a robot arm or the like. Then, the through-hole 110 connected to the gap S2 is provided in the flange portion 102 (refer to
Specifically, as shown in
By going through the above-described steps, the metal pipe 1 having the pipe portion 100 and the flange portions 101 and 102 can be formed. The time from the blow forming of the metal pipe material 14 to the completion of forming of the metal pipe 1 is approximately several seconds to several tens of seconds, although the time depends on the type of the metal pipe material 14. By changing the shapes of the cavities 16 and 24, it is possible to form a pipe portion having any shape such as a circular cross section, an elliptical cross section, and a polygonal cross section.
According to the metal pipe 1 formed by the forming method according to the above-described present embodiment, the gap S2 that communicates with the internal space S1 of the pipe portion 100 is positioned between the pair of inner surfaces 102a and 102b of the flange portion 102. The through-hole 110 provided in the flange portion 102 is connected to the gap S2. Accordingly, for example, even in a case where a liquid such as water has entered the internal space S1 of the pipe portion 100 when coating the metal pipe 1, the liquid can be easily discharged through the gap S2 and the through-hole 110. Thereby, the liquid is less likely to be collected inside the metal pipe 1, and thus, the generation of rust on the metal pipe 1 can be suppressed. In addition, for example, when the metal pipe 1 is immersed in the coating liquid, the through-hole 110 becomes an air escape hole. Accordingly, the inner peripheral surface 100a and the like of the pipe portion 100 can be excellently coated. Furthermore, it is possible to suppress the occurrence of collection of the coating liquid on the inner peripheral surface 100a or the like.
In the present embodiment, in the forming of the metal pipe 1, the plurality of gaps S2 positioned between the pair of inner surfaces 102a and 102b and intermittently disposed along the longitudinal direction X of the pipe portion 100 are formed, and the pair of inner surfaces 102a and 102b are in close contact with each other between the gaps S2 adjacent to each other along the longitudinal direction X. Therefore, the portion where the pair of inner surfaces 102a and 102b are in close contact with each other, and another member can be spot-welded. In addition, by the formation of the plurality of gaps S2 inside the flange portion 102, the liquid is less likely to be collected in the internal space S1 of the pipe portion 100. Therefore, it is possible to suppress the occurrence of intensity deterioration of the pipe portion 100, which is the main body of the metal pipe 1.
In the present embodiment, in the flange portion 102, the through-holes 110 may be provided for each of the plurality of gaps S2. In this case, it is possible to excellently suppress the collection of liquid inside the metal pipe 1.
The forming system 200 according to the embodiment includes: the metal pipe material 14 having a hollow shape; the forming apparatus 10 that is disposed between the upper die 12 and the lower die 11, expands the metal pipe material 14 by supplying a fluid, brings the metal pipe material 14 into contact with the upper die 12 and the lower die 11, and accordingly, forms the metal pipe 1 having the pipe portion 100 and the flange portion 101; and the processing device 210 that provides the through-hole 110 in the metal pipe 1, in which the forming apparatus 10 forms a gap which is positioned between the pair of inner surfaces of the flange portion 101 and communicates with the internal space of the pipe portion 100, and the processing device 210 provides the through-hole 110 connected to the gap in the flange portion 101.
According to the forming system 200, it is possible to obtain the action and effects having the same meaning as those of the above-described forming method.
Hereinafter, the metal pipe according to a modification example of the above-described embodiment will be described. In the description of the modification example, the description overlapping with the above-described embodiment will be omitted, and the portion different from the above-described embodiment will be described.
In the present modification example, the gap S2 is provided in the entire flange portion 102A. In addition, the flange portion 101A is also provided with a gap S3 as a whole. In other words, the gap S3 is provided between the inner surfaces 101a and 101b of the flange portion 101A. Therefore, each of the gaps S2 and S3 is continuously provided along the longitudinal direction X.
A part of the inner surface 101b of the flange portion 101A is provided with a protrusion portion 120 that protrudes toward the inner surface 101a. Accordingly, the part of the inner surface 101b is in close contact with the inner surface 101a. Similarly, apart of the inner surface 102b of the flange portion 102A is provided with the protrusion portion 120 that protrudes toward the inner surface 102a, and the part is in close contact with the inner surface 102a. Accordingly, the intensity of the metal pipe 1A can be improved. In the present modification example, each of the locations where the inner surfaces 101a and 101b are in close contact with each other and the location where the inner surfaces 102a and 102b are in close contact with each other can function as a spot-welded portion with other member. The dimension of the protrusion portion 120 along the longitudinal direction X is, for example, 10% or more and 50% or less of the dimension of the metal pipe 1A along the longitudinal direction X. The dimension of the protrusion portion 120 along the transverse direction Y is not particularly limited, but is appropriately adjusted according to the dimension of the protrusion portion 120 along the longitudinal direction X and the like.
A plurality of protrusion portions 120 are provided on each of the flange portions 101A and 102A. In the present modification example, the plurality of protrusion portions 120 provided on the flange portion 101A are provided at regular intervals along the longitudinal direction X, but the present disclosure is not limited thereto. Similarly, the plurality of protrusion portions 120 provided on the flange portion 102A are provided at regular intervals along the longitudinal direction X, but the present disclosure is not limited thereto. The protrusion portions 120 adjacent to each other in the longitudinal direction X are separated from each other.
Each of the protrusion portions 120 is formed, for example, by pressing the flange portions 101A and 102A after forming the metal pipe 1A. Otherwise, each of the protrusion portions 120 maybe provided, for example, when forming the metal pipe 1A. In this case, for example, a protrusion is provided at a part of the surface of the second protrusion 11c of the lower die 11. Accordingly, the protrusion portion 120 can be formed when the flange portions 101A and 102A are formed.
The through-hole 110A is provided on each of the flange portions 101A and 102A. The through-hole 110A is an opening connected to the gap S2 or the gap S3, and is provided so as to penetrate the inner surfaces 101b and 102b. The through-holes 110A provided in the flange portions 101A and 102A are positioned on the opposite side of the pipe portion 100A with the protrusion portion 120 therebetween in the transverse direction Y. In this case, the liquid is less likely to be collected on the tip end side (particularly, in the vicinity of the protrusion portion 120 from the viewpoint of surface tension) of the flange portions 101A and 102A. In addition, as shown in
In the present modification example, the through-hole 110A is provided corresponding to each of the protrusion portions 120, but the present disclosure is not limited thereto. The through-hole 110A may be provided in any of the flange portions 101A and 102A.
In the above-described modification example, the same effects as those in the above-described embodiment are exhibited. Since the gaps S2 and S3 are continuous in the longitudinal direction X, even in a case where the number of through-holes 110A formed in the flange portions 101A and 102A is reduced, the liquid can be excellently discharged through the gaps S2 and S3 and the through-holes 110A.
Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiment and the above-described modification examples. The above-described embodiment and the above-described modification example may be a combination with each other. For example, the metal pipe may be provided with the flange portions 101A and 102, or may be provided with the flange portions 101 and 102A. Further, the metal pipe is provided with one flange portion, or may be provided with three or more flange portions.
In the above-described embodiment and the above-described modification example, the through-hole is provided after forming the metal pipe, but the present disclosure is not limited thereto. The through-hole may be provided when forming the metal pipe.
In the above-described embodiment, the gap is provided only in one flange portion, but the present disclosure is not limited thereto. For example, the gap may be provided in both of the flange portions. In this case, through-holes may be provided in both of the flange portions.
In the above-described modification example, the flange portion is provided with the protrusion portion that protrudes from one inner surface toward the other inner surface, but the present disclosure is not limited thereto. For example, the protrusion portion that protrudes from the other inner surface toward one inner surface may be provided on the flange portion. Otherwise, the flange portion may be provided with both the protrusion portion that protrudes from one inner surface toward the other inner surface, and the protrusion portion that protrudes from the other inner surface toward one inner surface. The close contact between one inner surface and the other inner surface may be configured with the protrusion portion that protrudes from one inner surface toward the other inner surface and the protrusion portion that protrudes from the other inner surface toward one inner surface. The through-hole is provided on the opposite side of the pipe portion through the protrusion portion, but the present disclosure is not limited thereto.
In the above-described embodiment, gas is exemplified as the fluid to be supplied to the metal pipe material, but a liquid may be adopted as the fluid. The metal pipe material does not need to be heated during the forming. In other words, the metal pipe may be formed with hydrofoam.
In the example of the forming system 200 shown in
It should be understood that the invention is not limited to the above-described embodiment, but may be modified into various forms on the basis of the spirit of the invention. Additionally, the modifications are included in the scope of the invention.
Number | Date | Country | Kind |
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2019-039830 | Mar 2019 | JP | national |
Number | Date | Country | |
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Parent | PCT/JP2020/004985 | Feb 2020 | US |
Child | 17383103 | US |