JP2006068763A - Method for bending thin hollow bent metal sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bending method for applying a bending work to have a shape of a smooth curved surface in the longitudinal direction of a thin follow bent metal sheet by simple operation. <P>SOLUTION: In the bending work in the longitudinal direction of the thin hollow bent metal sheet the cross-sectional shape of which is rectangular and which has opening parts alternately on the front and back surfaces, by this bending method of the thin hollow bent metal sheet, after filling a metal sheet excellent in flexibility as a packing material in the opening parts of the thin hollow bent metal sheet, the bending work is applied. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bending method of a thin hollow folded plate material. More specifically, for example, in a multi-tube heat exchange type gas cooling device having a flat heat transfer tube, turbulent flow or vortex flow is applied to the fluid flowing inside and outside the heat transfer tube. Longitudinal bending of thin hollow folded plate materials that have a rectangular cross-sectional shape and have openings alternately on the front and back sides, such as corrugated fins that contribute to the generation and improvement of heat transfer performance between fluids Regarding the method.

  Normally, when a metal workpiece is bent by a draw vent or a press vent, the metallic workpiece, that is, the metallic workpiece, whether solid or hollow, Stress is generated by compression and tension on the side surface and the outer surface, and distortion occurs.This causes a wrinkle and a dent on the bent surface especially in the case of a hollow body, especially in a thin-walled hollow body. It is not uncommon for buckling to occur due to inability to withstand inward compressive strain. Therefore, bending of a metallic hollow extruded material or the like is performed by various bending means, and among them, a bending apparatus called a multi-bender as shown in FIG. As it can be easily bent in various shapes, its usefulness is enhanced in various processing fields. The bending apparatus 100 is disposed in front of the stationary mold 40 and has a work conduction hole 50a, and has a turning direction. The stationary mold 40 has a conduction hole 40a for the hollow workpiece 20 to be processed. A movable mold 50 supported so as to be displaceable, and a work feeder 60 that is disposed behind the fixed mold 40 and forcibly conducts the hollow work 20 in the work conduction hole 40a of the fixed mold 40, The work feeder 60 urges the turning / displacement operation of the movable mold 50 while forcibly conducting the hollow work 20 through the both mold conduction holes 40a, 50a, and continuously bending the hollow work 20 with the fixed mold 40 as a fulcrum. And a bending process of a predetermined bent shape with respect to the hollow workpiece 20 is performed.

  However, when the hollow work member 10 having a square cross-sectional shape as shown in FIG. 12A is subjected to bending with a small curvature radius in the same manner as described above using the bending apparatus 100, the bending portion has a wrinkle. There remains a problem of causing a serious defect in the quality of the bent portion by causing dents and buckling. Therefore, as shown in FIG. 12B, for example, the pitch (P) is 0.3 to 2.0 mm and the depth (D) is 0.00 on the inner peripheral surface and / or outer peripheral surface of the hollow cylindrical work member. When the corrugated surfaces 15 and 16 of 3 to 1.0 mm are formed in advance and then bent in the same manner as described above, the wrinkles and dents in the bent portion are absorbed by the corrugated surfaces 15 and 16. Alternatively, it has been reported that a good bent surface can be obtained without buckling or the like (see, for example, Patent Document 1).

  Further, in the double-pipe heat exchanger shown in FIG. 13A, as shown in FIG. 13B, a corrugated 240 made of a thin metal plate is formed on the inner surface of the inner pipe 120 through which high-temperature gas flows. The heat transfer fins 220 are incorporated to generate turbulence and vortex flow with respect to the gas flow, improve heat transfer with the cooling water flowing through the outer tube 140, and effectively exchange heat. However, when installing an engine room of a narrow automobile, for example, a straight pipe heat exchanger double pipe H as shown in FIG. 14 is provided from a bent portion C as shown in FIG. There is a need to bend at a bending angle α. However, when the double pipe H is left as it is, for example, when it is bent by a draw vent as shown in FIG. 16 or a press vent as shown in FIG. It is feared that the heat transfer fins 220 of the shape 240 partially generate wrinkles or buckle, and in the worst case, the gas flow path is blocked and the flow is blocked. In order to prevent such a phenomenon, a method of bending by filling an amorphous material such as sand or a flexible material is well known, but the amorphous material is contained in the inner tube 120 in which the heat transfer fins 220 are installed. It is extremely difficult to uniformly fill the packing made of, and further, the work of removing the packing after bending is more difficult, and in some cases, the packing cannot be completely removed, and the system It is feared that there will be inconvenience of remaining inside.

  In such a case, there is known a method of injecting water as an indeterminate filling material and freezing and then bending, but in the double pipe H as described above, the heat transfer fins 220 are provided in the inner pipe 120. When the water is frozen, it freezes from the outside, but it is difficult to secure a frozen state with sufficient strength to the extent that it can prevent clogging and space unevenness due to bending inside. It has been the established theory (see Non-Patent Document 1) that it can be applied only to bending of a pipe having a simple double structure.

However, in the bending method of the double pipe heat exchanger shown in FIGS. 13 to 17, both the inner pipe 120 and the outer pipe 140 are filled with water, and the water is frozen after being closed so as not to flow out. In an icing state, after bending at a predetermined bending angle α by a draw vent as shown in FIG. 16 or a press vent as shown in FIG. There is a report that the double pipe heat exchanger H can be bent (see Patent Document 2) in which the inner pipe 120 is provided with a corrugated 240 heat transfer fin 220 made of a thin metal plate without causing a phenomenon. Has been made.
Japanese Patent Laid-Open No. 6-71344 (pages 1 to 4, FIGS. 1 to 4) JP 2000-79417 A (pages 1 to 5, FIGS. 1 to 10) Masanobu Nakamura, “Pipe Processing Method”, Nikkan Kogyo Shimbun, 201-202

  In each of the above prior arts, the hollow workpiece to be bent is a rectangular cylindrical body in Patent Document 1, and the corrugated surface formed on the inner peripheral surface and / or the outer peripheral surface thereof. Estimated from pitch (P) and depth (D), it is assumed that the wall thickness is at least 1 mm or more, and it occurs during bending compared to thin metal folded plate material even though it is a hollow material. Such as wrinkles and buckling are less likely to occur. Moreover, although the to-be-processed member in the said patent document 2 is a corrugated tube substantially built in an inner pipe, according to the embodiment, 0.01-0.8 mm, Preferably it is 0.05-0.5 mm It literally corresponds to a metal sheet material, but is surrounded by a metal tube. Therefore, it is possible to select a means of injecting water and freezing, but the metal to be bent has a rectangular cross-sectional shape and has U-shaped openings alternately on the front and back sides. In the case of a thin-walled hollow folded plate material, it is impossible to adopt such means, and even if it is surrounded by a separate frame member, etc. In addition, the technical problem incurred a significant increase in cost, and in addition, a technical problem to obtain a uniform frozen state imposed a heavy burden. The workpiece in the present invention is a single metal thin hollow folded plate material having a rectangular cross-sectional shape as described above and having U-shaped openings alternately on the front and back, and the single member is left as it is or After being subjected to a predetermined bending process, for example, it is widely used for unique applications as a heat transfer fin or the like installed in an EGR gas cooling device. However, in each of the above prior arts, the bending method for such a metallic thin-walled hollow folded plate material has remained as an unsolved problem. The present invention has an object to solve such problems, and relates to a method of performing a predetermined bending process on a thin hollow folded plate material suitably used for the above-mentioned applications, and particularly, a bending. An object of the present invention is to provide a bending method in which a finished surface with almost no wrinkles, dents, or the like can be obtained by an easy operation, as well as prevention of buckling in processing.

  In order to solve the above problems, the present invention relates to a thin-walled hollow folded plate material having a rectangular cross-sectional shape and having openings alternately on the front and back sides. As a gist, the gist is a method for bending a thin-walled hollow folded plate material, which is characterized in that it is preferably subjected to bending after filling a large number of plates having excellent flexibility.

  The present invention is also characterized in that the thin-walled hollow folded plate material bending method is a draw vent or a press vent.

  The present invention is further characterized in that the filler used in the method of bending a thin hollow folded plate material is a metallic thin plate.

  The metal sheet according to the present invention is preferably a mild steel, spring steel, stainless steel, shape memory alloy, aluminum, aluminum alloy, Sn, Sn-based alloy, lead, lead alloy, zinc, zinc alloy, or the like. It is.

  Moreover, it is set as a preferable aspect that the plate | board thickness of the said metal thin plate which concerns on this invention is 0.05-0.3 mm.

  According to the bending method of the thin hollow folded plate material according to the present invention, the cross-sectional shape is rectangular and the front and back are alternately U-shaped openings, for example, the plate thickness is 0.05 mm or more and 0.3 mm. Even when the bent metal plate is bent by a draw vent or a press vent, the hollow folded plate material is hardly deformed such as wrinkles and dents, as well as being buckled. A smooth curved surface shape can be obtained. That is, according to the bending method according to the present invention, the hollow portion of the thin metal hollow folded plate material that is the workpiece, that is, the opening portion having a rectangular cross-sectional shape and U-shaped opening portions on the front and back sides is filled. After filling a plurality of plate materials having excellent flexibility as materials, a predetermined bending process is performed through a separately prepared mold, so that the folded plate material having a plane perpendicular to the bending direction can be compressed or It has been demonstrated that a finished surface having a smooth curved surface with almost no deformation such as buckling phenomenon due to strain due to tensile stress, wrinkles and dents can be obtained by a very simple operation, for example, an EGR gas cooling device As corrugated plate fins or the like that are internally mounted, it can be suitably employed. In addition, the filler used in the present invention is basically a metal thin plate having a thickness of 0.05 to 0.3 mm and excellent in flexibility, and the opening of the workpiece is filled without excess or deficiency. It functions as a deformation preventing material such as buckling prevention at the time of bending, and at the same time causes a springback phenomenon instantly after the end of bending, which facilitates workability in dismantling of molds and the like, and the opening Facilitates removal of filler from Therefore, even if it is a bending process which employ | adopts either a draw vent or a press vent, a bending process can be performed with respect to a metal thin hollow folded plate material by very simple operation.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.
FIG. 1 shows a stainless steel hollow folded plate material used for bending according to an embodiment of the present invention, wherein (a) is a plan view thereof, (b) is an enlarged front perspective view thereof, and (c) is an opening portion thereof. Fig. 2 is a plan view showing a state in which a thin plate made of stainless steel is filled, (d) is a rear view showing a state in which (c) is inverted 180 degrees, (e) is a front enlarged perspective view of (d), and Fig. 2 is the same. It is a three-plane figure which shows the metal mold | die for press vents used in an Example, (a) is a side view of a metal mold | die main body, (b) is a side view which shows one side pressure plate A, (c) is the other side surface clamp. FIG. 3 is a side view showing the plate B, and FIG. 3 is a two-side view showing a state where the workpiece shown in FIGS. 1C to 1E is assembled in the press vent mold shown in FIG. a) is a side view showing the way of assembling, (b) is an enlarged side view of the dashed-dotted line frame X in (a), and (c) is assembling. 4 is a side view showing the press vent state in the embodiment, (a) is a side view showing a state before compression, (b) is a schematic front view just before compression, and (c) is a side view showing completion. Side view at the time of completion of compression, (d) is a schematic front view showing a state after completion of compression, FIG. 5 shows a state of disassembling the die after the bending process according to the embodiment, (a) is a side presser plate A FIG. 6B is a side view showing a state immediately after removing B and B, FIG. 6B is an enlarged side view of the alternate long and short dash line Y in FIG. 6A, and FIG. (A) is a plan view thereof, (b) is a partially enlarged side view of a mold, and FIG. 7 shows a member to be processed and a filler after bending in the same embodiment. , (A) is a partial plan view of the filler, (b) is a partial plan view of the workpiece, (c) is an enlarged front view of the filler. FIG. 8D is a front enlarged perspective view of the workpiece, FIG. 8 shows another embodiment according to the present invention, and FIG. 8A is a perspective view of a sample to be bent of the workpiece in the embodiment. b) is a perspective view of a workpiece immediately after bending with a filler, FIG. 9 is a perspective view of the workpiece after bending of a comparative example according to the present invention, and FIG. 10 is a bending of another comparative example. It is a perspective view of the to-be-processed member immediately after a process.
[Example]

  Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited thereto, and can be freely modified within the scope of the gist of the present invention.

  The bending method according to the first embodiment of the present invention comprises a thin plate made of stainless steel having a thickness of 0.2 mm as a workpiece, as shown in FIGS. 1 (a) and 1 (b). A hollow folded plate material 1 for plate fins having a rectangular shape and having U-shaped openings 1-2 alternately on the front and back sides, having a width of 13 mm and a total length of 210 mm, and having nine irregularities in its longitudinal direction A corrugated (corrugated) curved surface was formed. Therefore, as shown in FIGS. 1C to 1E, the opening 1-2 of the folded plate 1 was filled with a filler 2 made of a stainless steel thin plate having a thickness of 0.1 mm with almost no gap. On the other hand, as shown in FIG. 2, the press vent mold 3 has a lower mold 3-1 and an upper mold 3-2 that form a corrugated shape, a bottom plate 3-3 that supports the mold, and both left and right side surfaces thereof. Left and right guide plates 3-4 and 3-5, and press plates A3-6 and B3-7 on the side surfaces thereof, and the guide plates 3-4 and 3-5 and the press plate A3 in this example. 6 and B 3-7 are integrally incorporated via bolts 4, and the workpiece 1 to be clamped between the lower mold 3-1 and the upper mold 3-2 is shown in FIGS. 3 (a) to 3 (c). As shown in Fig. 4, the guide is performed so that the pressing force is applied vertically and vertically in the longitudinal direction at the same time as pressing from the left and right side surfaces and the front and rear side surfaces. The press vent method in the present embodiment is as shown in FIGS. 4 (a) to 4 (d). For example, as shown in FIG. 4 (a), the center is aligned and fixed on the cradle of the 2t press. After that, as shown in FIGS. 4B and 4C, the movable punch descends and is gradually pressurized, and at the end of the press, the movable punch rises and the pressure is released. At the same time, a springback phenomenon occurs in the filler 2 inserted in the opening 1-2 of the workpiece 1 and the upper mold 3-2 temporarily rises. However, the hollow folded plate material 1 that is the workpiece 5 is completed without delay as shown in FIG. 5, and the disassembly of the mold 3 and the removal of the hollow folded plate material 1 shown in FIGS. 5 and 6 and the removal of the filler 2 that has been inserted are performed. As can be seen in FIGS. 6 (a) and 6 (b), no galling phenomenon was observed, and a smooth disassembly and removal operation could be realized.

  On the other hand, the hollow folded plate material 1 subjected to the bending process according to the present example has some unevenness on the contact surface with the mold 3 and the friction surface with the filler 2 as shown in FIG. However, the most avoidable buckling phenomenon does not occur at all, and a smooth curved surface is maintained at the 1-2 bent portion of the opening as shown in FIG. It has been confirmed that the smooth surface can be easily restored by the modification of the above, and it has been demonstrated that the object can be sufficiently used as a corrugated plate fin, which is the object of the present invention.

Using the folded folded plate material 1a made of the same material as in Example 1, bending with a curved bend radius XR using FIG. 8A as a sample was performed by a press vent substantially similar to that in Example 1. It was confirmed that the hollow folded plate material 1a after the end of the bending process can be provided for the intended purpose without requiring any modification process as shown in FIG. . It should be noted that the removal of the workpiece 1a and the removal of the filler 2a according to the present example are much simpler than those of the first embodiment, and the workability thereof is extremely excellent. It has been proven that reductions can be made.
[Comparative Example 1]

A bending test was performed on the hollow folded plate material 1a in the same manner as in Example 3 except that polyethylene having a thickness of 3.2 mm was inserted into the opening 1a-2 as a filler for preventing buckling. As a result, as shown in FIG. 9, it was confirmed that wrinkles and dents due to compressive deformation occurred strongly, and that a large amount of correction processing was necessary to meet the intended purpose.
[Comparative Example 2]

  A bending test was performed on the hollow folded plate material 1a under the same conditions as in Example 3 without inserting a filler for preventing buckling. As a result, as shown in FIG. 10, a large buckling phenomenon was generated in the bent portion so that the correction processing was almost impossible, which was almost the same as scrap.

  The above-mentioned filler for preventing buckling according to the present invention is capable of inserting, preferably a large number of metal thin plates having flexibility in the bending direction, into the entire width of the opening of the hollow molded folded plate material. It is necessary to absorb the deformation caused by bending by causing slippage between the inserted fillers, and to prevent the phenomenon that the opening of the hollow folded plate material is narrowed. Bending deformation proceeds smoothly while suppressing the occurrence of buckling of the wall of the opening.

  In order to achieve the above object, the filler inserted into the opening of the hollow folded plate material is flexible without changing its volume against compression caused by bending or buckling deformation caused by tension. It is desirable that the material is excellent in properties and hardly plastically deformed, and as the metal plate material, spring steel, stainless steel, shape memory alloy, etc. are suitable, and as the disposable metal plate material, mild steel, aluminum, Sn, lead, zinc, and alloys thereof may be mentioned, and the filler made of these metallic plates is preferably a thin plate in order to absorb the strain caused by compression and tension by causing slippage between the fillers. More specifically, a thickness of 0.05 to 0.3 mm is more desirable.

  As the bending means according to the present invention, a draw vent is also adopted in addition to the press vent according to each of the above embodiments, but the inside of the hollow folded plate material that is bent in any bending means, a reduction phenomenon due to compression, On the outside, elongation phenomena due to tension occur, and these phenomena generate distortion, which causes deformation such as buckling, wrinkles and irregularities on the hollow folded plate material. It is an essential requirement to insert the filler according to the present invention with respect to the full width of the part. Further, as the filler in the present invention, metal plate materials having different plate thicknesses and materials may be used in combination, and a lubricant may be applied to the surface of the plate material by application or spraying.

  As is clear from the above embodiments, according to the bending method of thin hollow folded plate material according to the present invention, a plurality of thin metal plates having excellent flexibility are inserted over the entire width of the opening of the hollow folded plate material. After filling, a thin hollow folded plate material having a smooth bending surface can be obtained by a simple operation of bending. The obtained thin-walled hollow folded plate material can be provided at a low price for various uses including corrugated plate fins incorporated in an EGR gas cooling device, for example, and thus a wide range of uses are expected in various industrial fields. .

1 shows a stainless steel hollow folded plate material used for bending according to an embodiment of the present invention, wherein (a) is a plan view thereof, (b) is an enlarged front perspective view thereof, and (c) is a stainless steel plate at an opening thereof. The top view which shows the state filled with the steel thin plate, (d) is a back view which shows the state which reversed (c) 180 degree | times, (e) is a front expansion perspective view of (d). It is a three-plane figure which shows the metal mold | die for press vents used in the Example, (a) is a side view of a metal mold | die main body, (b) is a side view which shows one side pressure plate A, (c) is the other side surface. 3 is a side view showing a presser plate B. FIG. In the Example, it is a two-plane figure which shows the state which incorporates the to-be-processed member shown to FIG.1 (c)-(e) in the metal mold | die for press vents shown in FIG. 2, (a) is a side view which shows the middle of an assembly, (B) is an enlarged side view of the dashed-dotted line frame X in (a), (c) is a side view which shows completion of assembly. It is a four-sided view showing the press vent state in the embodiment, (a) is a side view showing a state before compression, (b) is a schematic front view immediately before compression, (c) is a side view at the time of completion of compression, (d ) Is a schematic front view showing a state after completion of compression. The state which disassembles the metal mold | die after completion | finish of the bending process by the Example is shown, (a) is a side view which shows the state immediately after removing the side surface holding plates A and B, (b) is the dashed-dotted line frame Y in (a). FIG. In the same Example, after disassembling the mold, a state where a part of the workpiece and the filler are taken out is shown, (a) is a plan view thereof, and (b) is a partially enlarged side view of the mold. The member to be processed and the filler after the bending process in the embodiment are shown, (a) is a partial plan view of the filler, (b) is a partial plan view of the member to be processed, and (c) is a filler. (D) is a front enlarged perspective view of a workpiece. The other Example which concerns on this invention is shown, (a) is a perspective view of the bending plan sample of the to-be-processed member in the Example, (b) is a perspective view of the to-be-processed member just after the bending process filled with the filler. is there. It is a perspective view of the to-be-processed member immediately after the bending process of the comparative example which concerns on this invention. Similarly, it is a perspective view of a member to be processed immediately after bending of another comparative example. It is a partially broken vertical side view showing a bending state of a conventional hollow material. The hollow material to be processed used for bending in the above-described conventional example is shown, (a) is a perspective view of the prototype, and (b) is a perspective view showing a state in which a corrugated surface is formed for bending. The conventional double tube heat exchanger is shown, (a) is the side view, (b) is the II line cross-sectional enlarged view in (a). It is a perspective view which shows the double tube in the said heat exchanger. It is a perspective view of the said double pipe after a bending process. It is a side view which shows typically the draw vent apparatus used in the said prior art example. It is a side view which shows typically the press vent apparatus used in the said prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a Thin hollow folded plate material 1-1, 1a-1 Convex part 1-2, 1a-2 Opening part 1-3, 1a-3 Section 2, 2a Filler 3 Mold 3-1 Lower mold 3-2 Top Mold 3-3 Bottom plate 3-4 Right side guide plate 3-5 Left side guide plate 3-6 Side guide plate A
3-7 Side guide plate B
4 bolts

Claims (5)

In the longitudinal bending method of a thin hollow folded plate material having a rectangular cross-sectional shape and having openings alternately on the front and back sides, a plurality of plate materials excellent in flexibility are filled in the openings of the thin hollow folded plate material. And then bending the thin hollow folded plate material. The method for bending thin-walled hollow folded plate material according to claim 1, wherein the bending is a draw vent or a press vent. The method for bending a thin-walled hollow folded plate material according to claim 1 or 2, wherein the filler is a metallic thin plate. The metal thin plate is made of mild steel, spring steel, stainless steel, shape memory alloy, aluminum, aluminum alloy, Sn, Sn-based alloy, lead, lead alloy, zinc, zinc alloy, or the like. Bending method for thin hollow folded plate material. The method of bending a thin hollow folded plate material according to any one of claims 1 to 4, wherein the metal thin plate has a thickness of 0.05 to 0.3 mm.

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