Method of manufacturing mixing pipe component of cooking stove burner

Abstract

To provide a method of manufacturing a mixing pipe component of a cooking stove burner capable of appropriately preventing large strain at a flange portion around a base portion of a swelled portion subjected to deep drawing processing.SOLUTION: A method of manufacturing a mixing pipe component of a cooking stove burner having a swelled portion formation step of forming a swelled portion 2 that swells toward the front surface side of a metal plate 1A by applying deep drawing processing to the metal plate 1A as a raw material, and forming a flange portion 19 around a base portion of the swelled portion 2, has a strain correction step of correcting strain of the flange portion 19 after the swelled portion formation step. In the strain correction step, a punch 7A having a first press surface 71a with a convex curved surface shape is utilized, and the first press surface 71a is brought into contact with a back surface of the flange portion 19 to press the flange portion 19.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a mixing tube component of a stove burner. [Background technology]

[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 holes provided in a burner cap, and the burner cap is usually placed on the upper side of the mixing tube. The mixing tube of such a stove burner is made of, for example, aluminum die casting, but this makes the manufacturing cost high. One possible method for reducing the manufacturing cost of the mixing tube is to form the components of the mixing tube by pressing a metal plate, for example.

[0003] However, when the above-mentioned means is adopted, there are problems to be solved as described below.

[0004] That is, a specific example of a component of a mixing tube is a component having a bulge that bulges out on the front side (upper surface side) and a flat flange portion located around the base of the bulge. When forming such a component by deep drawing a metal plate, distortion is likely to occur in the flange portion. This distortion causes the flange portion to deform into a convex shape on the back side (convex shape on the lower surface side). Moreover, the greater the drawing depth of the bulge portion, the greater the distortion. This makes the flange portion non-flat, so that when other components of the mixing tube are assembled to the flange portion, it is difficult to properly bring these flange portions and other components into close contact with each other. As a result, there is a risk of an undesirable gap being generated between them, or a problem such as a rattle being generated. It is desirable to properly solve such a problem. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-21147 A [Patent Document 2] Patent No. 3739915 [Patent Document 3] JP 2019-27669 A [Patent Document 4] JP 2002-282952 A [Patent Document 5] Patent No. 6818229 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention was devised under the circumstances described above, and has an object to provide a manufacturing method for a mixing tube component of a stove burner that can appropriately prevent significant distortion in the flange portion formed around the base of the bulge portion when the mixing tube component of a stove burner is manufactured through a process of deep drawing a metal plate to form a bulge portion. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides the following technical solutions.

[0008] The method for producing a mixing tube component of a stove burner provided by the present invention comprises the steps of: A manufacturing method for a mixing tube component for a stove burner includes a bulge forming process in which a metal plate is subjected to deep drawing to form a bulge that bulges out on the front side of the metal plate and a flange portion is formed around the base of the bulge, and further includes a distortion straightening process in which distortion of the flange portion is corrected after the bulge forming process, wherein the distortion straightening process uses a punch having a convex curved first press surface, and presses the flange portion by abutting the first press surface against the back surface of the flange portion.

[0009] According to this configuration, the following effects can be obtained. That is, even if distortion (distortion due to deep drawing of the bulging portion) occurs in the flange portion of the metal plate at the stage where the bulging portion forming process is completed, this distortion is corrected by the distortion correction process executed thereafter. The distortion of the flange portion before correction causes the flange portion to be deformed into a convex shape on the back side, whereas in the distortion correction process, the convex curved first press surface of the punch is pressed against the back side of the flange portion to actively press and deform the flange portion in the opposite direction to the distortion direction. Therefore, it is possible to achieve a superior effect in eliminating the distortion of the flange portion compared to, for example, pressing the flange portion with a simple flat surface. For this reason, it is possible to appropriately manufacture a mixing tube component for a stove burner having a flange portion with a distortion appropriately corrected. As a result, when another mixing tube component is assembled to the mixing tube component, it is possible to prevent defects such as a large gap caused by the distortion or rattling between the flange portion and the other mixing tube component.

[0010] In the present invention, preferably, the punch comprises a plurality of first blocks whose tip surfaces form the first press surface, and a first base portion that holds the plurality of first blocks in a spaced-apart arrangement so as to be in opposing contact with the rear surface of the flange portion.

[0011] With this configuration, it is possible to facilitate the manufacture of the punch used in the distortion straightening process and reduce the cost. That is, as another aspect of the first press surface of the punch, it is possible to form the first press surface as a loop-shaped surface in plan view so as to correspond to the flange portion of the mixing tube component, but this has the disadvantages that it is difficult to process the first press surface, the punch is not easy to manufacture, and the manufacturing cost is high. In contrast, with the punch of the above configuration using multiple first blocks, it is possible to eliminate the above disadvantages.

[0012] In the present invention, preferably, in the distortion correction process, a die having a second press surface that is concavely curved or flat corresponding to the convexly curved first press surface is also used, and the flange portion is pressed so as to be sandwiched between the first and second press surfaces.

[0013] According to this configuration, in the distortion straightening step, the flange portion is sandwiched between the convexly curved first press surface of the punch and the concavely curved or flat second press surface of the die, so that the distortion straightening effect of the flange portion can be further improved. Note that, through tests by the present inventors, it has been found that the distortion straightening effect intended by the present invention can be sufficiently obtained even when the second press surface is flat instead of concavely curved.

[0014] In the present invention, preferably, the die comprises a plurality of second blocks whose tip surfaces form the second press surface, and a second base portion that holds the plurality of second blocks in a spaced-apart arrangement so as to be in opposing contact with the surface of the flange portion.

[0015] According to this configuration, it is possible to simplify the manufacture of the die used in the distortion straightening step and reduce the cost. For example, when forming a second press surface having a loop shape in a plan view corresponding to the flange portion, the processing may be difficult and the cost may be high. In contrast, the above-mentioned configuration can eliminate or reduce such a risk.

[0016] Other features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0017] [Figure 1] 1(a) is a schematic cross-sectional view of a main part showing an example of a stove burner, in which of a pair of upper and lower mixing tube components of the stove burner shown in this figure, the lower mixing tube component corresponds to an example of the object to be manufactured by the manufacturing method of the present invention, and (b) is a cross-sectional view taken along line Ib-Ib of (a). [Diagram 2] FIG. 2 is a schematic perspective view of a pair of upper and lower mixing tube components of the stove burner shown in FIG. [Diagram 3] FIG. 3(a) is a cross-sectional view of the lower mixing tube component shown in FIG. 1 and FIG. 2, FIG. 3(b) is a plan view of FIG. 3(a), and FIG. 3(c) is a cross-sectional view of FIG. 3(a) taken along line IIIc-IIIc. [Figure 4] 5(a) and 5(b) are cross-sectional views showing an example of a bulge forming step in the manufacturing method of the present invention. [Diagram 5] 5(a) is a plan view of an intermediate mixing tube component manufactured through the bulge portion forming process shown in FIG. 4, (b) is a cross-sectional view taken along line Vb-Vb of (a), and (c) is a cross-sectional view taken along line Vc-Vc of (a). [Figure 6] FIG. 6A is a cross-sectional view showing an example of a distortion straightening step in the manufacturing method of the present invention, FIG. 6B is an explanatory plan view showing the positional relationship between the intermediate product of the mixing tube component shown in FIG. 6A and a plurality of first press surfaces of a punch, and FIG. 6C is a cross-sectional view of a different portion of FIG. 6A, which corresponds to the cross-sectional view taken along the line VIc-VIc of FIG. 6B. [Figure 7]7A is a plan view of an intermediate mixing tube component manufactured through the distortion straightening process shown in FIG. 6, FIG. 7B is a cross-sectional view taken along line VIIb-VIIb of FIG. 7A, FIG. 7C is a cross-sectional view taken along line VIIc-VIIc of FIG. 7A, and FIG. 7D is a cross-sectional view taken along line VIId-VIId of FIG. [Figure 8] FIG. 8 is a cross-sectional view showing an example of a first trimming process step for the intermediate product of the mixing tube component shown in FIG. 7. [Figure 9] FIG. 8 is a plan view showing an example of a second trimming process for the intermediate product of the mixing tube component shown in FIG. 7. [Figure 10] FIG. 11 is a cross-sectional view of a main portion showing another example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

[0019] First, for ease of understanding, the configuration of the stove burner B shown in Fig. 1 will be described. In this embodiment, the lower mixing tube component ML of the stove burner B, which will be described later, is the object of manufacture.

[0020] The 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 formed by combining a pair of upper and lower mixing tube components MU and ML, forming a mixture flow path 6. From the gas nozzle 52, fuel gas is ejected from the vicinity of the air inlet 60 toward the inside of the tubular flow path 6a of the mixture flow path 6. Then, primary air flows into the mixture flow path 6 from the air inlet 60, and the mixture of this primary air and the fuel gas advances through the mixture flow path 6 and is finally led to a plurality of flame holes 50b provided in the head portion 50a of the burner cap 50. The fuel gas in the mixture that flows out from these plurality of flame holes 50b to the outside is ignited by the ignition plug 51 and burns.

[0021] The upper mixing tube component MU is formed by pressing a metal plate such as a stainless steel plate. This mixing tube component MU has a bulge 4 and an upwardly extending The bulge 4 has a convex portion 30 (see also FIG. 2). The bulge 4 has a cylindrical peripheral wall portion 40 that stands upward from the plate-like region 3 and an upper wall portion 41 that is connected to the upper portion of the peripheral wall portion 40, and a burring hole portion 43 is provided in the upper wall portion 41. The upward convex portion 30 constitutes the upper wall portion of the tubular flow path portion 6a and has a cross-sectional shape that is approximately semicircular and forms a concave groove portion 30a on the lower surface side. The bulge 4 functions as a support base for the burner cap 50. The burring hole portion 43 (as well as the burring hole portion 23 described later) is used as an insertion guide hole portion 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 mixture supplied to the second region 61b of the chamber 61 described later of the mixture flow path 6 is guided to the flame hole 50b of the burner cap 50 by passing through the gap.

[0022] The lower mixing tube component ML is formed by pressing a metal plate such as a stainless steel plate, similarly to the upper mixing tube component MU. As shown in Figs. 2 and 3, this mixing tube component ML has a bulging portion 2 and a downwardly convex portion 10. The bulging portion 2 has a cylindrical peripheral wall portion 20 that stands upward from the plate-like region 1 and an upper wall portion 21 that is connected to the upper portion of the peripheral wall portion 20, and the upper wall portion 21 is provided with a burring hole portion 23 in which a downwardly protruding burring portion 24 is provided on the peripheral portion. As shown in Fig. 1, the cylindrical portion 50c of the burner cap 50 is fitted into this burring hole portion 23. The downwardly convex portion 10 constitutes the lower wall portion of the tubular flow passage portion 6a, and has a cross-sectional shape that is approximately semicircular and forms a concave groove portion 10a on the upper surface side.

[0023] As shown in Fig. 1, the bulge 2 is fitted into the lower part of the bulge 4 of the upper mixing tube component MU, thereby forming a chamber 61 of the mixture flow path 6 between these two bulge parts 2, 4. The chamber 61 includes a first region 61a sandwiched between the peripheral walls 20, 40 of the two bulge parts 2, 4, as well as a second region 61b sandwiched between the upper walls 21, 41 of the two bulge parts 2, 4. The peripheral wall 20 of the bulge part 2 is formed with a pair of steps 22 (see Figs. 2 and 3) that extend at an angle in the vertical direction. The pair of steps 22 are portions for partitioning and forming the mixture flow path 6. A first region 61a of the chamber 61 is formed in the region between the peripheral wall portions 20, 40, closer to the tubular flow path portion 6a than the pair of step portions 22, and the second region 61b of the chamber 61 and the tubular flow path portion 6a are connected via this first region 61a.

[0024] 4 to 9 show an example of a manufacturing method for the lower mixing tube component ML, the details of which will be described below.

[0025] To manufacture the lower mixing tube component ML, first a bulge forming process (first bulge forming process) as shown in FIG. 4(a) is carried out, and then a second and third bulge forming process are further carried out to manufacture an intermediate product ML' of the mixing tube component as shown in FIG. 5 (note that the intermediate product ML' will have a different structure as it is subsequently subjected to processing, but the same reference numerals are used). That is, in the initial bulge forming step shown in FIG. 4(a), a flat metal plate 1A is deep-drawn to form a prototype bulge 2A. This prototype bulge 2A is a part that will be the prototype of the final bulge 2 (see FIG. 3), and has a peripheral wall 20 that stands upward (standing on the surface side) from the plate-like region 1 of the metal plate 1A, and an upper wall 21. Preferably, the height H1 of the prototype bulge 2A is set higher than the finishing target height H3 (see FIG. 3) of the final bulge 2, and the height of the prototype bulge 2A is lowered as the bulge forming step is repeated, so that the size approaches the final target size. By adopting such a method, it is possible to appropriately prevent the bulge 2 from becoming thin-walled and to prevent cracks and the like from occurring in the bulge 2. In addition, in the plate-like region 1, a flange portion 19, which is a region around the base of the bulging portion 2 (peripheral wall portion 20), is distorted and is actually non-flat as shown by the imaginary line La in the same figure. (This also applies to FIG. 4(b), and the details of the distortion will be described later.)

[0026] 4(b), a processing is performed to form a bulge 2' having a height H2 that is lower than the height H1 of the original bulge 2A based on the original bulge 2A. Also, an initial step 22a that will eventually be finished as the step 22 is formed in the peripheral wall 20.

[0027] After the second bulge forming process, a third bulge forming process is further performed to manufacture an intermediate product ML' shown in FIG. 5. In this third bulge forming process, bulge processing is performed to set the height H3 of the bulge 2 to a height of the final finishing target size even lower than the height H2 of the bulge 2' in FIG. 4. The peripheral wall 20 of the bulge 2 is formed to a final finishing target shape and size, and processing is simultaneously performed to finish the step 22 by enlarging the initial step 22a in FIG. 4(b). Furthermore, processing is simultaneously performed to form a downward convex portion 10 having a concave groove portion 10a in the plate-like region 1.

[0028] At the stage where the third bulge forming process is completed, the flange portion 19 of the intermediate product ML', which is the peripheral region of the base of the bulge portion 2, is distorted and non-flat. In Fig. 5(b) and (c), the flange portion 19 is shown simplified as a flat plate portion inclined at an appropriate angle α. However, in reality, this is not limited to this, and the flange portion 19 may be distorted so as to be curved. In any case, the distortion of the flange portion 19 causes the flange portion 19 to be deformed into a convex shape on the back side (convex shape on the lower surface side). It is considered that such distortion is caused by the generation of springback-like stress when the metal plate 1A is deep-drawn to form the bulge portion 2.

[0029] After the third bulge forming step, a distortion straightening step is carried out to straighten the distortion of the flange portion 19. In this distortion correction process, a press machine A equipped with a punch 7A and a die 7B as shown in FIG. 6 is used. Here, the punch 7A is equipped with a plurality of first blocks 70A and a first base portion 72A. The basic form of each of the plurality of first blocks 70A is a rectangular parallelepiped, but the tip surface thereof is a first press surface 71a having a convex curved surface that is convex downward. In this embodiment, the first press surface 71a is a curved surface that has an arc-shaped cross section, but the present invention is not limited to this, and it is also possible to make it a non-arc-shaped curved surface (a curved surface in which the radius of curvature of each part is not constant). It is also possible to make it a curved surface that is asymmetric left and right or front and back (this also applies to the second press surface 71b described later).

[0030] 6(b), the first blocks 70A are held by the first base portion 72A in a circular arrangement spaced apart from each other in a plan view so as to face the flange portion 19 of the intermediate product ML'. The holding means for each of the first blocks 70A is a means for fitting each of the first blocks 70A into a plurality of recesses 75a provided in the first base portion 72A.

[0031] The die 7B includes a plurality of second blocks 70B and a second base portion 72B. The plurality of second blocks 70B are basically rectangular parallelepiped-shaped like the first block 70A. However, the upward tip surface is a second press surface 71b that is concave downward. The plurality of second blocks 70B are arranged in the same manner as the plurality of first blocks 70A shown in FIG. 6(b) (arranged in a ring shape with a gap therebetween) and are held by the second base portion 72B. The holding means is a means in which the plurality of second blocks 70B are fitted into the plurality of recesses 75b provided in the second base portion 72B.

[0032] In the distortion correction process, as shown in FIG. 6(c), a punch 7A and a die 7B are arranged in a plurality of positions. The flange portion 19 of the intermediate product ML' is sandwiched and pressed by the first and second press surfaces 71a, 71b. At this time, the first press surface 71a is set to abut against the back surface of the flange portion 19 (the side where the bulging portion 2 does not bulge), and the second press surface 71b is set to abut against the front surface of the flange portion 19. This distortion straightening process makes it possible to straighten the distortion of the flange portion 19. As described above, the distortion of the flange portion 19 is caused by deforming the flange portion 19 into a convex shape on the back surface side, but the above-mentioned distortion straightening process presses the flange portion 19 so as to actively deform it in the direction opposite to the distortion direction. Therefore, it is possible to enhance the effect of straightening the distortion of the flange portion 19. This distortion straightening step provides an intermediate product ML' in which the distortion of the flange portion 19 has been straightened, as shown in Fig. 7. The flange portion 19 may be in the shape of a flat plate or a shape close to this.

[0033] In addition, in Fig. 7, an additional processing portion 18 is provided in a part of the intermediate product ML'. This additional processing portion 18 is a portion formed at the same time as the distortion straightening process is performed, and is, for example, a portion in which a cut portion 18a and a bent portion 18b are provided in a part of the plate-shaped region 1. As shown in Fig. 6(a), the punch 7A is provided with an auxiliary portion 76 for forming the additional processing portion 18. In this embodiment, the process of providing the additional processing portion 18 is performed at the same time as the distortion straightening process is performed. According to such a configuration, it is not necessary to separately perform a dedicated work process for providing the additional processing portion 18, which is advantageous in reducing the total number of work processes.

[0034] After completing the distortion straightening process, first and second trimming processes are performed as shown in Fig. 8 and Fig. 9. In the first trimming process in Fig. 8, a burring hole 23 is formed in the upper wall 21 of the bulge 2 of the intermediate product ML'. In the second trimming process in Fig. 9, the outer shape of the plate-like region 1 of the intermediate product ML' is trimmed to a final target shape (the shape shown by the imaginary line in the figure).

[0035] By going through the series of steps described above, it is possible to properly manufacture the lower mixing tube component ML shown in FIGS. In the manufacturing process described above, a distortion straightening step is performed to properly straighten distortion of the flange portion 19. Therefore, as shown in Fig. 1, when the upper mixing tube component MU is superimposed on the lower mixing tube component ML, no large gap occurs at the flange portion 19, and they can be properly assembled.

[0036] As described above, the punch 7A and the die 7B used in the distortion straightening process are configured such that a plurality of first and second blocks 70A, 70B each having a first and second press surface 71a, 71b are held by a first and second base portion 72A, 72B. This makes it possible to appropriately facilitate the manufacture of the punch 7A and the die 7B and reduce the cost. That is, if the first and second press surfaces 71a, 71b are each formed into a continuous loop shape in plan view corresponding to the flange portion 19, for example, there is a disadvantage that the processing and manufacturing of the first and second press surfaces 71a, 71b is quite troublesome. In contrast, according to the configuration of this embodiment, the first and second press surfaces 71a, 71b are easily formed, and there is no such disadvantage.

[0037] Fig. 10 shows another embodiment of the present invention. In this figure, elements that are the same as or similar to those in the above embodiment are given the same reference numerals as in the above embodiment, and duplicated explanations will be omitted.

[0038] The second press surface 71b' of the die 7B of the press device A' shown in FIG. 10 is flat. Even in this configuration, the flange portion is pressed by the pressing action of the first press surface 71a. 19 distortion correction can be performed appropriately. As can be seen from this embodiment, the second press surface can be, for example, flat instead of concavely curved.

[0039] The contents of the present invention are not limited to the contents of the above-mentioned embodiment. The specific configuration of each step of the manufacturing method of the mixing tube component of the stove burner according to the present invention can be freely changed in various ways within the intended scope of the present invention.

[0040] In the above embodiment, the bulge forming step is performed three times in total, but the present invention is not limited to this. The bulge forming step may be performed at least once. The punch and die used in the distortion correction process may differ from the above-described embodiment in that they do not have a plurality of first and second blocks having first and second press surfaces (for example, the first and second press surfaces are not provided on each of a plurality of blocks, but are provided on the punch or die in a loop shape in plan view or a shape similar thereto). In the above embodiment, the case of manufacturing the lower mixing tube component ML has been described, but the present invention is not limited to this. The present invention can also be used to manufacture the upper mixing tube component MU, and any mixing tube component of a stove burner having a bulge and a flange can be suitably manufactured using the manufacturing method of the present invention. In the press apparatuses A and A' shown in Fig. 6 and Fig. 10, the punch 7A is the upper die and the die 7B is the lower die, but the present invention is not limited to this. It is also possible to use a configuration that is upside down from Fig. 6 and Fig. 10, that is, a configuration in which the punch 7A is the lower die and the die 7B is the upper die. [Explanation of symbols]

[0041] B Convection Burner M mixing tube ML mixing tube component (lower mixing tube component) ML' Mixing tube component intermediate product 1 Plate-like region 1A metal plate 19 Flange 2 Bulge 7A Punch 7B Die 70A, 70B First and second blocks 71a, 71b First and second press surfaces 72A, 72B First and second base parts

Claims

1. A method for manufacturing a mixing tube component of a stove burner, comprising a step of forming a bulge portion on a surface side of a metal plate as a raw material by deep drawing, and forming a flange portion around a base of the bulge portion, The method further includes a distortion correction step of correcting distortion of the flange portion after the bulge portion forming step, A manufacturing method for a mixing tube component of a stove burner, characterized in that in the distortion correction process, a punch having a first press surface shaped like a convex curve is used, and the first press surface is abutted against the back surface of the flange portion to press the flange portion.

2. A method for manufacturing a mixing tube component of a stove burner according to claim 1, comprising the steps of: The method for manufacturing a mixing tube component of a stove burner, wherein the punch comprises a plurality of first blocks whose tip surfaces form the first press surface, and a first base portion that holds the plurality of first blocks in a spaced-apart arrangement so that they can come into opposing contact with the back surface of the flange portion.

3. A method for manufacturing a mixing tube component of a stove burner according to claim 1 or 2, comprising the steps of: This method for manufacturing a mixing tube component for a stove burner includes using a die having a second press surface that is concavely curved or flat corresponding to the convexly curved first press surface in the distortion correction process, and pressing the flange portion so as to sandwich it between the first and second press surfaces.

4. A method for manufacturing a mixing tube component of a stove burner according to claim 3, comprising the steps of: The method for manufacturing a mixing tube component of a stove burner, wherein the die is provided with a plurality of second blocks whose tip surfaces form the second press surface, and a second base portion that holds the plurality of second blocks in a spaced-apart arrangement so that they can come into opposing contact with the surface of the flange portion.

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