Method of manufacturing a pipe coupling component

A method of manufacturing upper and lower structural members used in a casing comprising a casing main body which is composed of a top wall, a bottom wall, and a circumferential wall and through which fluid flows;

• and a fluid passage section provided on the casing main body and composed of a base portion communicating with the interior of the casing main body, and a tubular pipe coupling portion extending from a distal end of the base portion, wherein the upper structural member forms the top wall of the casing main body, an upper half portion of the circumferential wall of the casing main body, an upper half portion of the base portion of the fluid passage section, and an upper half portion of the pipe coupling portion of the fluid passage section;
• and the lower structural member forms the bottom wall of the casing main body, a lower half portion of the circumferential wall of the casing main body, a lower half portion of the base portion of the fluid passage section, and a lower half portion of the pipe coupling portion of the fluid passage section, the method comprising:
• a first step of producing a first intermediate product for the upper structural member by performing press work on a metal blank plate using two dies, each die having a shape corresponding to a final shape of the upper structural member, the first intermediate product including a top wall forming portion that forms the top wall of the casing main body, a circumferential wall forming portion that forms the upper half portion of the circumferential wall of the casing main body, a base portion forming portion that forms the upper half portion of the base portion of the fluid passage section, a semi-tubular coupling portion forming portion that forms the upper half portion of the pipe coupling portion of the fluid passage section, and flat portions integrally formed along opposite side edges of the coupling portion forming portion and being located on the common plane, wherein round portions are formed at boundaries between the inner circumferential surface of the coupling portion forming portion and surfaces of the flat portions facing a direction toward which the coupling portion forming portion is open;
• a second step of producing a second intermediate product for the lower structural member by performing press work on a metal blank plate using two dies, each die having a shape corresponding to a final shape of the lower structural member, the second intermediate product including a bottom wall forming portion that forms the bottom wall of the casing main body, a circumferential wall forming portion that forms the lower half portion of the circumferential wall of the casing main body, a base portion forming portion that forms the lower half portion of the base portion of the fluid passage section, a semi-tubular coupling portion forming portion that forms the lower half portion of the pipe coupling portion of the fluid passage section, and the flat portions integrally formed along opposite side edges of the coupling portion forming portion and being located on the common plane, wherein round portions are formed at boundaries between the inner circumferential surface of the coupling portion forming portion and surfaces of the flat portions facing a direction toward which the coupling portion forming portion is open;
• a third step of deforming the flat portions of each second intermediate product so that the flat portions move toward the direction toward which the coupling portion forming portion is open, to thereby produce a third intermediate product for each of the upper and lower structural members, which product is larger in bending depth of the coupling portion forming portion and smaller in width of the flat portions than the first intermediate product;
• a fourth step of bending portions of the flat portions of each third intermediate product located on the side toward the coupling portion forming portion so that the bent portions form acute angles in relation to opposite side walls of the coupling portion forming portion and form obtuse angles in relation to outer portions of the flat portions, to thereby produce a fourth intermediate product for each of the upper and lower structural members, which product includes a coupling portion forming portion, sloping flat portions extending from the opposite side walls of the coupling portion forming portion, and narrow flat portions extending from distal edges of the sloping flat portions, being located on the common plane, and being narrower than the flat portions of the third intermediate product;
• a fifth step of pushing the sloping flat portions of each fourth intermediate product, in a direction away from a bottom portion of the coupling portion forming portion, toward the side walls of the coupling portion forming portion, while restraining distal edge portions of the narrow flat portions, so as to move material of the intermediate product to boundaries between the sloping flat portions and the side walls of the coupling portion forming portion, to thereby produce a fifth intermediate product for each of the upper and lower structural members;
• a sixth step of pressing, from upper and lower sides, opening-side portions of the side walls of the coupling portion forming portion, the sloping flat portions, and the narrow flat portions of each fifth intermediate product, to thereby produce a sixth intermediate product for each of the upper and lower structural members which product includes a coupling portion forming portion having the same depth as the upper and lower structural members of the final shape, and final flat portions extending from the opposite side walls of the coupling portion forming portion and being identical in shape and dimension with the upper and lower structural members of the final shape, wherein burrs project toward the interior of the coupling portion forming portion from opening-side end portions of the side walls of the coupling portion forming portion;
• and
• a seventh step of removing the burrs from each sixth intermediate product, to thereby produce the upper and lower structural members of the final shape each of which includes a coupling portion forming portion which is to come into close contact with an outer circumferential surface of a pipe, and the final flat portions which are integrally formed along opposite side edges of the coupling portion forming portion and are located on the common plane, wherein edge portions are formed at boundaries between the inner circumferential surface of the coupling portion forming portion and surfaces of the final flat portions, the surfaces facing a direction toward which the coupling portion forming portion is open.

A method of manufacturing a pipe coupling that prevents leakage comprising the steps of:

• forming a semi-tubular portion and flat portions along opposite sides of the semi-tubular portion;
• deforming the flat portions to produce larger bending depth and smaller width;
• bending portions of the flat portions to form bent portions so that the bent portions form acute angles in relation to the semi-tubular portion with sloping flat portions extending from the semi-tubular portion, and distal narrow flat portions;
• pushing the sloping flat portions away from the semi-tubular portion;
• pressing the semi-tubular portion, the sloping flat portions, and the narrow flat portions to produce a final shape having final flat portions;
• and
• removing burrs so that the semi-tubular portion of the final shape comes into close contact with an outer circumferential surface of a pipe, and the final flat portions are integrally formed along opposite side edges of the semi-tubular portion in a common plane.