Abstract: A pressing apparatus includes a lower die (24) fixed to a lower plate (11), and first and second plate (11), and first and second upper die punches (33 and 34) capable of being lifted and lowered along with an upper plate (12). The first upper die punch (33) supported by a spring (49) is capable of being lifted and lowered relative to the second upper die punch (34). The upper plate (12) is lifted and lowered, while intermittently feeding a band-shaped work (W) one pitch by one pitch from the right to the left along an upper surface of the lower die (24), thereby pressing the work (W) to form grooves in the work (W) continuously. When the groove is formed in the work (W) by pressing the work (W) by the second upper die punch (34), the groove formed at the last time by pressing the work (W) by the second upper die punch (34) is retained and positioned between the first upper die punch (33) and the lower die (24).

Abstract: A body member and flange members are butted together at a first abutment portion and a second abutment portion. The first and second abutment portions are held by first and second backing jigs, respectively. The first backing jig has a circumscribing recessed section corresponding to an inner circumferential surface of the first abutment portion. Further, the first backing jig has a circumscribing opening communicated with the bottom of the recessed section. On the other hand, the second backing jig has a circumscribing recessed section corresponding to an inner circumferential surface of the second abutment portion. Further, the second backing jig has a circumscribing opening communicated with the bottom of the recessed section. First and second buffer members are attached to the recessed sections, respectively.

Abstract: A pressing apparatus includes a lower die (24) fixed to a lower plate (11), and first and second plate (11), and first and second upper die punches (33 and 34) capable of being lifted and lowered along with an upper plate (12). The first upper die punch (33) supported by a spring (49) is capable of being lifted and lowered relative to the second upper die punch (34). The upper plate (12) is lifted and lowered, while intermittently feeding a band-shaped work (W) one pitch by one pitch from the right to the left along an upper surface of the lower die (24), thereby pressing the work (W) to form grooves in the work (W) continuously. When the groove is formed in the work (W) by pressing the work (W) by the second upper die punch (34), the groove formed at the last time by pressing the work (W) by the second upper die punch (34) is retained and positioned between the first upper die punch (33) and the lower die (24).

Abstract: A body member and flange members are butted together at a first abutment portion and a second abutment portion. The first and second abutment portions are held by first and second backing jigs, respectively. The first backing jig has a circumscribing recessed section corresponding to an inner circumferential surface of the first abutment portion. Further, the first backing jig has a circumscribing opening communicated with the bottom of the recessed section. On the other hand, the second backing jig has a circumscribing recessed section corresponding to an inner circumferential surface of the second abutment portion. Further, the second backing jig has a circumscribing opening communicated with the bottom of the recessed section. First and second buffer members are attached to the recessed sections, respectively.

Abstract: Ends of heat-transfer plates S1, S2, formed by bending folding plate blanks in a zigzag fashion along folding lines L1, L2, are cut in an angle shape, and flange portions 26 formed by folding apexes of the angle shape are superposed one on another and brazed in a surface contact state, thereby to form combustion gas passage inlets 11 and air passage outlets 16 along the two end edges of the angle shapes. Compared with brazing of separate flange members onto the cut surfaces of the apexes of the angle shapes, this fabrication not only dispenses with precise finishing of the cut surfaces, but also serves to increase the brazing strength.

Abstract: Ends of heat-transfer plates S1, S2, formed by bending folding plate blanks in a zigzag fashion along folding lines L1, L2, are cut in an angle shape, and flange portions 26 formed by folding apexes of the angle shape are superposed one on another and brazed in a surface contact state, thereby to form combustion gas passage inlets 11 and air passage outlets 16 along the two end edges of the angle shapes. Compared with brazing of separate flange members onto the cut surfaces of the apexes of the angle shapes, this fabrication not only dispenses with precise finishing of the cut surfaces, but also serves to increase the brazing strength.

Abstract: First heat-transfer plates S1 and second heat-transfer plates S2 are radially arranged between a larger diameter cylindrical-shaped outer casing 6 and a smaller diameter cylindrical-shaped inner casing 7 to form combustion gas passages 4 and air passages 5 alternately in a circumferential direction, and a multiplicity of projections 22, 23 formed on both surfaces of the first heat-transfer plates S1 and second heat-transfer plates S2 are jointed to one another at tip ends thereof. Pitches P between adjacent projections 22, 23 are changed in a radial direction to make the number of heat transfer units substantially constant in a radial direction to uniformize temperature distributions on the first heat-transfer plates S1 and second heat-transfer plates S2 in the radial direction, thereby avoiding a decrease in heat exchanging efficiency and generation of unwanted thermal stress.

Abstract: First heat transfer plates S1 and second heat transfer plates S2 folded along crest folding lines L1 and valley folding lines L2 are bonded to an inner periphery of an outer casing 6 and an outer periphery of an inner casing 7, so that the first and second heat transfer plates S1 and S2 are disposed radiately, thereby forming combustion gas passages and air passages circumferentially alternately. One end of both the combustion gas passages and the air passages is cut into an angle shape, and one side and the other side of the angle shape are closed to form combustion gas passage inlets 11 and air passage outlets 16. In a similar manner, combustion gas passage outlets 12 and air passage inlets 15 are formed at the other end of the combustion gas passages and the air passages. Thus, it is possible to provide a heat exchanger which has a simple structure and is easy to manufacture, and in which the pressure loss due to bending of flow paths can be suppressed to the minimum.