Manufacturing method for mixing tube components of a stove burner

Abstract

To provide a manufacturing method of a mixing pipe formation member of a cooking stove burner which enables a burring part to be provided properly having a relatively large vertical width at an upper wall part of a predetermined expansion part when processing is performed to a metal plate to manufacture the mixing pipe formation member of the cooking stove burner.SOLUTION: A manufacturing method of a mixing pipe formation member of a cooking stove burner has: an expansion part formation step in which deep drawing processing is performed on a metal plate 1A prepared as a raw material to form a predetermined expansion part 2; and a burring hole part formation step in which a burring hole part 23, in which a burring part 24 having a downward protruding cylindrical shape is located at a peripheral edge part, is formed at an upper wall part 21 of the expansion part 2. In the expansion part formation step, a prototype expansion part 2A having a height higher than that of the expansion part 2 having a final finishing target size is formed and then expansion part processing for reducing the height of the expansion part 2 to the final finishing target size is performed. After the expansion part processing is performed at least one time and then the burring hole part formation step is performed.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for manufacturing a mixing tube constituent member of a stove burner.

BACKGROUND ART

[0002] A stove burner is generally configured to include a mixing tube, as described in, for example, Patent Documents 1 to 3. The mixing tube is a member for guiding a mixture of fuel gas and air to a plurality of flame ports provided in a burner cap, and it is customary that the burner cap is placed on the upper side of this mixing tube. Such a mixing tube for a stove burner is made of, for example, aluminum die-cast, but this leads to high manufacturing costs. As a means for reducing the manufacturing cost of the mixing tube, for example, a means of forming the constituent member of the mixing tube by subjecting a metal plate to press working can be considered.

[0003] However, when the aforementioned means is adopted, there is a problem to be improved as described below.

[0004] That is, when the constituent member of the mixing tube is configured using a metal plate, there is a case where it is desired to provide an upwardly rising bulging portion by utilizing a part of this metal plate, and to form a burring hole portion in which a cylindrical burring portion protruding downward is located at the inner peripheral edge on the upper wall portion of this bulging portion. Here, such a burring hole portion is used, for example, to fit a part of the burner cap to fix and hold it. Therefore, it is desired that the cylindrical burring portion of this burring hole portion be formed to have a vertical width that is a relatively large width equal to or greater than a certain level. However, since the aforementioned burring portion is a portion obtained by extending a part of the upper wall portion of the bulging portion that bulges upward by deep drawing downward, if an attempt is made to increase the vertical width of this burring portion, the burring portion will be significantly thinned, and defects such as cracks are likely to occur. Therefore, it is difficult to appropriately form this burring portion so that the vertical width of the burring portion is relatively large. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2001-21147 [Patent Document 2] Patent No. 3739915 [Patent Document 3] Japanese Patent Publication No. 2019-27669 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention was conceived under the circumstances described above, and its objective is to provide a method for manufacturing a stove burner mixing tube component that enables the appropriate provision of a burring portion with a relatively large vertical width on the upper wall of a predetermined bulge when manufacturing a stove burner mixing tube component by processing a metal plate. [Means for solving the problem]

[0007] To solve the above problems, the present invention employs the following technical measures.

[0008] The method for manufacturing a mixing tube component of a stove burner provided by the present invention comprises a bulge forming step, in which a metal sheet as a raw material is subjected to deep drawing to form a bulge having a cylindrical peripheral wall portion that rises upward from a plate-like region of the metal sheet and an upper wall portion connected to the upper part of the peripheral wall portion, and A method for manufacturing a mixing tube component of a stove burner, comprising a burring hole forming step, in which a burring hole is formed in the upper wall portion, in which a cylindrical burring portion protruding downward is located at the periphery, wherein in the bulge forming step, a prototype bulge portion that will serve as the prototype for the bulge portion is formed by deep drawing, in which a prototype bulge portion that is taller than the final finished target size bulge portion is formed first, then a bulge processing step is performed to reduce the height of the prototype bulge portion to make it the final finished target size bulge portion, and after performing the bulge processing step at least once, the burring hole forming step is performed.

[0009] This configuration yields the following effects: In other words, when an upward-facing, upright bulge is formed in the plate-like region of a metal sheet by deep drawing during the bulge formation process, the upper wall of the bulge generally becomes thin, making it difficult to provide a burring hole with a large vertical width in this upper wall. However, according to the present invention, a prototype bulge that is taller than the final target size of the bulge is formed first, and the volume of the metal material constituting the entire prototype bulge is made large. Then, a bulge processing is performed to reduce the height of this prototype bulge, and then a burring hole is formed in the upper wall of this bulge. Therefore, at the time of forming the burring hole, the volume of the metal material constituting the upper wall can be kept large. Consequently, even if the vertical width of the burring is relatively large, the burring does not become excessively thin, and it is possible to appropriately prevent cracks from forming.

[0010] In the present invention, preferably, the bulging process is repeated multiple times, and after the bulging is formed to the final target size by these multiple bulging processes, the burring hole formation process is performed.

[0011] With this configuration, by repeating the bulging process multiple times, it is possible to more effectively increase the volume of the material (metal material) that constitutes the upper wall of the bulging portion. Since the burring hole formation process is performed in this state, it is even more preferable for appropriately forming a burring portion with a large vertical width.

[0012] In the present invention, preferably, the process further includes a step-forming step in which a step is formed on the peripheral wall of the bulging portion to constitute a part of the mixed gas flow path of the stove burner, and the burring hole forming step is performed after the step-forming step is completed.

[0013] With this configuration, it is possible to form a stepped section on the peripheral wall of the bulge section, which constitutes part of the mixed air flow path of the stove burner. However, at the time the stepped section is formed, the burring section is not yet present. Therefore, the burring section does not get in the way when the stepped section is formed, and there is no risk of damaging the burring section during the process.

[0014] In the present invention, preferably, the process performed before the burring hole formation process includes a step-pressing process in which a stepped-pressed portion is formed in a region near the center of the upper wall of the bulging portion, which is convex on the lower side and concave on the upper side, and a pilot-hole processing process in which a pilot hole smaller in diameter than the stepped-pressed portion and the burring hole is provided in the stepped-pressed portion, and in the burring hole formation process, the burring hole is provided in the stepped-pressed portion and a part of the stepped-pressed portion is formed as the burring portion.

[0015] With this configuration, a portion of the stepped recess formed on the upper wall of the bulging section is formed as a burring section, which allows for a reasonable and unforced increase in the vertical width of the burring section.

[0016] In the present invention, preferably, the stepped pressing portion includes a planar wall portion that is circular in plan view and located closer to the center of the upper wall portion of the bulging portion, and an inclined wall portion that is located between the planar wall portion and a region closer to the outer peripheral edge of the upper wall portion, is annular in a circular shape in plan view, and is inclined such that the height decreases toward the position closer to the center of the upper wall portion. In the burring hole portion forming step, the burring hole portion is provided in the stepped pressing portion, and the inclined wall portion is made to serve as the burring portion.

[0017] According to such a configuration, among the stepped pressing portions formed on the upper wall portion of the bulging portion, the inclined wall portion that is annular in a circular shape in plan view and decreases in height toward the center is formed as the burring portion, so that no large load or stress is generated, and the burring portion can be formed more smoothly and appropriately.

[0018] Other features and advantages of the present invention will become more apparent from the following description of the embodiments of the invention with reference to the accompanying drawings. [Brief Description of the Drawings]

[0019] [Figure 1] (a) is a schematic cross-sectional view of main parts showing an example of a stove burner. Of the pair of upper and lower mixing tube constituent members of the stove burner shown in this figure, the lower mixing tube constituent member corresponds to an example of the manufacturing target of the manufacturing method according to the present invention, and (b) is an Ib-Ib cross-sectional view of (a). [Figure 2] It is a schematic perspective view of the pair of upper and lower mixing tube constituent members of the stove burner shown in Figure 1. [Figure 3] (a) is a cross-sectional view of the upper mixing tube constituent member shown in Figure 1 and Figure 2, and (b) is a IIIb-IIIb cross-sectional view of (a). [Figure 4] (a) is a cross-sectional view of the lower mixing tube constituent member shown in Figure 1 and Figure 2, (b) is a plan view of (a), and (c) is an IVc-IVc cross-sectional view of (a). [Figure 5] It is a cross-sectional view showing an example of the first step when manufacturing the mixing tube constituent member by the manufacturing method of the present invention. [Figure 6] This is a cross-sectional view showing an example of the second step when manufacturing a mixing tube constituent member by the manufacturing method of the present invention. [Figure 7] (a) is a cross-sectional view showing an example of the third step when manufacturing a mixing tube constituent member by the manufacturing method of the present invention, and (b) is a partially enlarged cross-sectional view of (a). [Figure 8] (a) is a cross-sectional view showing an example of the fourth step when manufacturing a mixing tube constituent member by the manufacturing method of the present invention, and (b) is a partially enlarged cross-sectional view of (a). [Figure 9] (a) is a cross-sectional view showing an example of the fifth step when manufacturing a mixing tube constituent member by the manufacturing method of the present invention, and (b) is a partially enlarged cross-sectional view of (a). [Description of Embodiments]

[0020] Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

[0021] First, for ease of understanding, the configuration of the stove burner B shown in FIG. 1 will be described. In the present embodiment, the below-described lower mixing tube constituent member ML of the stove burner B is the manufacturing target.

[0022] The stove burner B includes a mixing tube M, a burner cap 50, a temperature sensor 53, an ignition plug 51, and a gas nozzle 52. The mixing tube M is configured by combining a pair of upper and lower mixing tube constituent members MU and ML, and forms a mixed gas flow path 6. Fuel gas is ejected from the gas nozzle 52 toward the inside of the tubular flow path portion 6a of the mixed gas flow path 6 from the vicinity of the air supply port 60. Then, accompanying this, primary air flows into the mixed gas flow path 6 from the air supply port 60, and the mixture of this primary air and the fuel gas travels through the mixed gas flow path 6, and is finally guided to a plurality of flame ports 50b provided in the head portion 50a of the burner cap 50. The fuel gas in the air-fuel mixture flowing out from the plurality of flame ports 50b to the outside is ignited by the ignition plug 51 and combusted.

[0023] The upper mixing tube component MU is formed by press-forming a metal plate, such as a stainless steel plate. As is clearly shown in Figures 2 and 3, this mixing tube component MU has a bulge 4 and an upward-facing convex portion 30. The bulge 4 has a cylindrical peripheral wall portion 40 that rises upward from the plate-like region 3 and an upper wall portion 41 connected to the upper part of this peripheral wall portion 40, and a burring hole portion 43 is provided in the upper wall portion 41. The upward-facing convex portion 30 has a substantially semicircular cross-section that constitutes the upper wall portion of the tubular flow path portion 6a and forms a recessed groove portion 30a on its lower surface side. The bulge 4 functions as a support base for the burner cap 50. The burring hole portion 43 (and the burring hole portion 23 described later) is used as an insertion guide hole for the cylindrical portion 50c of the burner cap 50 and the temperature sensor 53. There is a gap between the burring portion 44 of the burring hole portion 43 and the cylindrical portion 50c of the burner cap 50, and the air-mixed gas supplied to the second region 61b of the chamber 61, which will be described later, is guided to the flame hole 50b of the burner cap 50 by passing through this gap.

[0024] The lower mixing tube component ML, like the upper mixing tube component MU, is formed by press-forming a metal plate such as a stainless steel plate. As is clearly shown in Figures 2 and 4, this mixing tube component ML has a bulge 2 and a downward-facing convex portion 10. The bulge 2 has a cylindrical peripheral wall portion 20 that rises upward from the plate-like region 1 and an upper wall portion 21 connected to the upper part of this peripheral wall portion 20, and a burring hole portion 23 is provided in the upper wall portion 21. The downward-facing convex portion 10 has a substantially semicircular cross-section that constitutes the lower wall portion of the tubular flow path portion 6a and forms a recessed groove portion 10a on its upper surface.

[0025] As shown in Figure 1, the bulge portion 2 is fitted into the lower part of the bulge portion 4 of the upper mixing tube component MU, thereby forming a chamber 61 of the mixed gas flow path 6 between the two bulges 2 and 4. The chamber 61 includes a first region 61a sandwiched between the peripheral walls 20 and 40 of the two bulges 2 and 4, as well as a second region 61b sandwiched between the upper walls 21 and 41 of the two bulges 2 and 4. The peripheral wall 20 of the bulge portion 2 has a pair of stepped portions 22 (see Figures 2 and 4) that extend inclined in the vertical direction. These pair of stepped portions 22 correspond to specific examples of "stepped portions for forming a part of the mixed gas flow path of a stove burner" as referred to in the present invention. Between the peripheral wall portions 20 and 40, a first region 61a of the chamber 61 is formed in the portion closer to the tubular flow path portion 6a than the pair of stepped portions 22, and the second region 61b of the chamber 61 and the tubular flow path portion 6a are in communication via this first region 61a.

[0026] The bulging portion 2 is equipped with an upper wall portion 21 connected to the upper part of the peripheral wall portion 20, and a burring hole portion 23 is provided in this upper wall portion 21. This burring hole portion 23 is a portion in which a cylindrical burring portion 24 protrudes downward from its peripheral edge. As shown in Figure 1, the cylindrical portion 50c of the burner cap 50 is fitted into this burring hole portion 23, and airtight sealing is required in this fitted portion to prevent the mixed gas from leaking downward. For this reason, in addition to the dimensional accuracy of the inner diameter of the burring portion 24, its vertical width La is required to be a relatively long dimension. However, simply trying to make the vertical width La relatively long would result in a significant thinning of the burring portion 24, making it prone to defects such as cracking.

[0027] Figures 5 to 9 show an example of a manufacturing method for the lower mixing tube component ML described above, and the first to fifth steps are shown as the steps for this method, which are executed sequentially. Here, steps 1 to 3 correspond to specific examples of the "bulge formation step" as defined in the present invention. The fourth step corresponds to a specific example of the "pre-drilling process." Step 5 corresponds to a specific example of the "burring hole formation step". Furthermore, the third step also corresponds to the "step pressing step." The second and third steps are the "step formation step." This also applies to ''.

[0028] To manufacture the lower mixing tube component ML, the first step shown in Figure 5 is performed first. In this first step, for example, a flat metal plate 1A is deep-drawn to form a prototype bulge 2A, which will serve as the prototype for the final bulge 2 (see Figure 4). This prototype bulge 2A has a peripheral wall portion 20 and an upper wall portion 21 that rise upward from the plate-like region 1 of the metal plate 1A. However, the height H1 of this prototype bulge 2A is higher than the height H3 of the target finished size of the final bulge 2. The diameter of the prototype bulge 2 is approximately the same as, or slightly larger than, the diameter of the final bulge 2.

[0029] In the second step shown in Figure 6, a bulge processing is performed to form a bulge 2' with a height H2 that is lower than the height H1 of the original bulge 2A. Also in the second step, an initial stepped portion 22a, which will ultimately be finished as a stepped portion 22, is formed on the peripheral wall portion 20.

[0030] In the third step shown in Figure 7, a bulge machining process is performed to lower the height H3 of the bulge 2 to a height H2 of the bulge 2' in Figure 6, thereby setting it to the target final finished size. The peripheral wall portion 20 of the bulge 2 is formed to the target final finished shape and size, and the step portion 22 is finished simultaneously by increasing the initial step portion 22a in Figure 6. In addition, a downward-facing convex portion 10 having a recessed groove portion 10a on its upper side is also formed in the plate-like region 1.

[0031] Furthermore, in the third step, a process is performed to form a stepped recessed portion 21b on the upper wall portion 21 of the bulging portion 2. As is clearly shown in Figure 7(b), this stepped recessed portion 21b has a circular planar wall portion Sa located near the center of the upper wall portion 21 and a circular ring-shaped inclined wall portion Sb located near the center of the upper wall portion 21. The inclined wall portion Sb is located between the planar wall portion Sa and the region 21a near the outer edge of the upper wall portion 21, and is inclined so that its height gradually decreases as it moves closer to the center of the upper wall portion 21. The inclined wall portion Sb may be formed as a simple inclined surface, but in this embodiment, it has two curved cross-sections Aa and Ab with different directions of curvature and radii of curvature Ra and Rb. (Examples of the first and second curved sections) The shape is said to be smoothly connected. Preferably, Ra <Rbである。

[0032] In the fourth step shown in Figure 8, a pilot hole 23a for forming a burring hole 23 is provided in the planar wall portion Sa of the stepped recess 21b of the upper wall portion 21 of the bulging portion 2. This pilot hole 23a has a smaller diameter than the stepped recess 21b and the burring hole 23.

[0033] In the fifth step shown in Figure 9, a burring hole 23 is formed in the upper wall portion 21 of the bulging portion 2. This burring hole 23 is formed by providing a hole in the stepped pressing portion 21b, but preferably, the remaining area of ​​the planar wall portion Sa of the stepped pressing portion 21b is removed, and substantially the entire inclined wall portion Sb (curved cross-section portions Aa, Ab) of the stepped pressing portion 21b is formed as a cylindrical burring portion 24.

[0034] Through the series of steps described above, it is possible to properly manufacture the lower mixing tube component ML shown in Figures 2 and 4. In the manufacturing process described above, first, a prototype bulge 2A is formed that is taller than the final target size bulge 2. The volume of the metal material that makes up the entire prototype bulge 2A is made large, and then the height of the prototype bulge 2A is reduced to form the final target size bulge 2. As a result, when forming the burring hole 23, the volume of the metal material that makes up the upper wall 21 of the bulge 2 can be made large, and even if the vertical width of the burring 24 is made relatively large, it is possible to appropriately suppress the thinning of the burring 24 and prevent cracks from forming.

[0035] Furthermore, as a method for forming the burring portion 24, as shown in Figures 7 to 9, a downwardly convex stepped portion 21b is formed on the upper wall portion 21 of the bulging portion 2, and then a part of this stepped portion 21b, the inclined wall portion Sb (curved cross-section portions Aa, Ab), is formed as the burring portion 24. This is preferable in that it prevents thinning of the burring portion 24 while increasing the vertical width of the burring portion 24.

[0036] The present invention is not limited to the embodiments described above. The specific configuration of each step in the method for manufacturing the mixing tube component of a stove burner according to the present invention can be modified in various ways within the scope intended by the present invention.

[0037] In the above-described embodiment, the prototype bulge 2A is formed in the first step, and then the bulge 2 of the final target size is formed through a total of two bulge processing steps (processing to reduce the height of the bulge) in the second and third steps, after which the burring hole formation step is performed. However, the present invention is not limited to this. In the present invention, the bulge processing only needs to be performed at least once. [Explanation of Symbols]

[0038] B. Stove burner M mixing tube ML mixing tube component (lower mixing tube component) Sa Planar wall section (stepped section) Sb Inclined wall section (stepped section) 1. Plate-like region 1A metal plate 2 Bulge 20 Peripheral wall section 21 Upper wall 21a Region near the outer edge ( Upper wall (of the department) 22 Step section 23 Burring hole 24 Burring section 6. Mixed gas flow path

Claims

1. A process to form a bulge by deep drawing a metal sheet as a raw material, thereby forming a bulge having a cylindrical peripheral wall portion that rises upward from the plate-like region of the metal sheet and an upper wall portion connected to the upper part of this peripheral wall portion, The process of forming a burring hole in the upper wall portion, in which a cylindrical burring portion that protrudes downward is located at the periphery, A method for manufacturing a mixing tube component of a stove burner, having the following characteristics: In the bulge formation process, a prototype bulge, which will serve as the model for the bulge, is formed by deep drawing, with a height greater than that of the final target size bulge. Then, a bulge processing is performed to reduce the height of the prototype bulge and make it the final target size bulge. After performing the aforementioned bulging portion processing at least once, the burring hole formation step is performed, The process performed before the burring hole formation process includes a step-pressing process in which a step-pressed portion is formed in the central region of the upper wall of the bulging portion, which is convex on the lower side and concave on the upper side. In this step-pressing process, the step-pressing portion is formed to have a planar circular wall portion located near the center of the upper wall portion, and a planar circular ring-shaped inclined wall portion located between the planar wall portion and the outer peripheral edge region of the upper wall portion, and inclined such that its height decreases as it approaches the center of the upper wall portion. The inclined wall portion has a first curved cross-section portion that protrudes downward in a rounded manner from the inner circumference of the region near the outer edge, and a second curved cross-section portion that protrudes upward in a rounded manner from the outer circumference of the planar wall portion. The lower part of the first curved section and the upper part of the second curved section are directly connected, and the radius of curvature Rb of the second curved section is greater than the radius of curvature Ra of the first curved section. In the process of forming the burring hole, the burring hole is provided in the stepped portion, and the inclined wall portion is made into the burring portion. A method for manufacturing a mixing tube component of a stove burner, characterized by the above.

2. A method for manufacturing a mixing tube component of a stove burner according to claim 1, A method for manufacturing a mixing tube component of a stove burner, wherein the bulging process is repeated multiple times, and after the bulging is formed to the final target size through these multiple bulging processes, the burring hole formation process is performed.

3. A method for manufacturing a mixing tube component of a stove burner according to claim 1, The process further includes a step-forming step in which a step is formed on the peripheral wall of the bulging portion to constitute a part of the mixed air flow path of the stove burner. A method for manufacturing a mixing tube component of a stove burner, comprising completing the step-forming step and then performing the burring hole forming step.

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