JP2013202615A - Tube expanding billet, tube expanding device, and heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain: a tube expanding billet capable of expanding a tube in a stable state without damaging heat transfer promoting fins on an inner surface of a heat transfer tube when expanding the tube or without damaging heat transfer performance; a tube expanding device using the tube expanding billet; and a heat exchanger.SOLUTION: A tube expanding billet 2 is used for expanding a heat transfer tube 1 with a plurality of heat transfer promoting fins 11 having projected cross sections extending to the longitudinal direction and projected on an inner peripheral surface. A plurality of projection parts 22 contacting an inner peripheral surface in the heat transfer tube 1 between the adjacent heat transfer promoting fins 11, projecting to the radial direction so as to expand the heat transfer tube 1, and having the maximum outer diameter part at the center part in the axial direction and concave grooves 21 formed between the adjacent projection parts 22 for receiving the heat transfer promoting fins 11 are alternately formed in the circumferential direction of an outer peripheral surface. A chamfer 23 formed so that an excised part can be enlarged as it approaches the edge side by a surface inclined to a tangent direction with respect to a rotation locus is provided at the edge in the tube expanding direction of the projection parts 22.

Description

  The present invention relates to a tube expansion billet, a tube expansion device, and a heat exchanger that are used when, for example, heat transfer tubes inserted through fins for heat exchangers are expanded and fixed to each other.

  As a conventional pipe expansion billet, a plurality of concave grooves having a maximum outer diameter larger than the inner diameter of the pipe (heat transfer pipe) and extending in the axial direction on the outer peripheral surface and fitted with the inner fin of the pipe are spaced apart in the circumferential direction. The tube expansion member is formed in the pipe with the inner fin fitted in the groove, using a tube expansion member (expansion billet) that is formed in the groove and the width and depth of the groove is larger than the width and height of the inner fin. In some cases, the portion between the adjacent grooves on the outer peripheral surface of the expanding member is pressed to expand the tube by pressing a portion where the inner fin does not exist on the inner surface of the expanding member (see, for example, Patent Document 1).

JP-A-9-253775 (page 2-3, FIGS. 1 and 2)

  In the conventional tube expansion billet (tube expansion member) as described above, the outer shape of the expanded tube is not distorted, and the effect of preventing the inner fin from being crushed at the time of tube expansion is obtained. As shown in FIG. 2, the distal end portion of the expanded billet in the insertion direction has only a small outer diameter, so that when the expanded billet is inserted into the heat transfer tube, the distal end of the inner fin and the expanded tube There is a problem that the concave groove of the billet may come in contact with the inner fin of the heat transfer tube, or the mandrel connected to the expanded billet may be broken.

  The present invention has been made to solve the above-mentioned problems, and does not damage the heat transfer promotion fins on the inner surface of the heat transfer tube during pipe expansion, and does not impair the heat transfer performance. It aims at obtaining the pipe expansion billet which can be performed, the pipe expansion apparatus using the pipe expansion billet, and a heat exchanger.

  The tube expansion billet according to the present invention is a tube expansion billet used for tube expansion of a heat transfer tube in which a plurality of heat transfer promotion fins having a convex cross section and extending in the longitudinal direction are projected on the inner peripheral surface, and the heat transfer promotion fins adjacent to each other A plurality of ridges protruding in the radial direction so as to abut on the inner peripheral surface of the heat transfer tube between them and having a maximum outer diameter portion in the axial central portion, and the adjacent ridges Grooves that are formed between the portions and that receive the heat transfer promotion fins are alternately formed in the circumferential direction of the outer peripheral surface, and at the tube expansion direction tip of the ridge portion with respect to the tangential direction with respect to the rotation locus A chamfered portion formed such that the cut portion becomes larger toward the tip end side by the inclined surface is provided.

  In the tube expanding billet according to the present invention, the tube expanding billet is formed by chamfering the distal end portion of the ridge portion in the tube expanding direction with a surface inclined with respect to the tangential direction with respect to the rotation trajectory so that the cut portion becomes larger toward the distal end side. When the heat transfer tube is inserted into the heat transfer tube, the heat transfer promotion fin of the heat transfer tube comes into contact with the chamfered portion at the tip of the ridge, the tube expansion billet is rotated in the circumferential direction, and the ridge is guided between the heat transfer promotion fins. Is done. For this reason, the protruding end portion of the heat transfer promoting fin is not damaged, and breakage of the mandrel connected to the tube expansion billet is prevented, and the tube can be expanded smoothly.

The perspective view which shows the external appearance at the time of inserting the pipe expansion billet by Embodiment 1 of this invention into a heat exchanger tube. The front view which shows schematic structure of the pipe expansion apparatus by Embodiment 1 of this invention. It is a figure explaining the principal part of the pipe expansion billet shown by FIG. 1, (a) is an expansion perspective view, (b) shows the chamfering part vicinity of the convex part (only 1 line | wire is shown) of the pipe expansion direction front-end | tip part. A perspective view and (c) are front views which explain chamfering part notionally. Sectional drawing which shows the state by which the pipe expansion billet shown by FIG. 1 was inserted in the heat exchanger tube. The principal part perspective view which shows the front-end | tip part vicinity of the pipe expansion billet by Embodiment 2 of this invention. The perspective view which shows the pipe expansion billet by Embodiment 3 of this invention. Sectional drawing which shows schematic structure of the pipe expansion billet shown by FIG. It is a figure which shows roughly the principal part external appearance of the heat exchanger by Embodiment 4 of this invention, (a) is a top view, (b) is a front view. It is a figure explaining the heat exchanger tube of the heat exchanger shown by FIG. 8, (a) is a fragmentary sectional view, (b) is the fragmentary cross section of the heat exchanger tube expanded using the conventional tube expansion billet as a comparative example. Figure.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing an external appearance when a billet according to Embodiment 1 of the present invention is inserted into a heat transfer tube, FIG. 2 is a front view showing a schematic configuration of the tube expanding device according to Embodiment 1 of the present invention, and FIG. FIG. 2 is a diagram for explaining a main part of the pipe expansion billet shown in FIG. 1, (a) is an enlarged perspective view, and (b) is a chamfered portion in the vicinity of a protruding strip (only one strip is shown) at the tip of the pipe expansion direction. The perspective view to show, (c) is a front view which illustrates a chamfer part notionally. 1 to 4, a heat transfer tube 1 to be expanded has a plurality of heat transfer promotion fins 11 projecting in the center direction at an equally divided angle on the inner peripheral surface and having a convex cross section and extending straight in the longitudinal axial direction. In addition, a groove-like recess 12 is formed between adjacent heat transfer promotion fins 11.

  In the outer peripheral portion of the pipe expansion billet 2, a concave groove 21 provided at a position corresponding to the heat transfer promotion fin 11 so as not to damage the heat transfer promotion fin 11, and a desired outside larger than the inner diameter of the heat transfer pipe 1 The ridges 22 protruding in the radial direction so as to have a diameter are alternately formed in the circumferential direction. The height of the ridge 22 is set to be larger than the fin height of the heat transfer promotion fin 11 of the heat transfer tube 1. The width of the protruding portion 22 is set to be slightly narrower than the interval between the heat transfer promotion fins 11 of the heat transfer tube 1. The tip of the protruding portion 22 on the side inserted into the heat transfer tube 1 is constricted so as to start from a position where the tip of the heat transfer promotion fin 11 of the heat transfer tube 1 contacts the inner peripheral direction.

  Note that the height of the ridges 22 may be gradually increased from the position where the tips in the inner circumferential direction of the heat transfer promotion fins 11 of the heat transfer tube 1 come into contact. In addition, a through hole 2a is provided at the axial center of the pipe expansion billet 2, and the pipe expansion billet 2 is held by a mandrel 3 inserted through the through hole 2a. The tube expansion billet 2 has a maximum outer diameter portion at the center in the axial direction, and is formed in a shape in which the rear end portion is narrowed together with the tip portion in the tube expansion direction (the lower right direction in FIG. 1).

  As shown in FIG. 3, one of the typical features of the pipe expansion billet 2 of the present invention is that the pipe expansion tip of the ridge 22 is inclined with respect to the direction tangent A to the rotation locus. The chamfered portion 23 is chamfered in the shape of a triangular pyramid so that the cut portion becomes larger toward the side. In this example, as shown in FIGS. 3 (b) and 3 (c), the tip of the chamfered portion 23 in the tube expansion direction includes one corner portion 22 a of the protruding end of the protruding strip portion 22 and the root portion 22 b of the protruding strip portion 22. It is cut off along a diagonal line B to be connected. In addition, the chamfered portion 23 is similarly provided at the front end portion and the rear end portion in the pipe expanding direction of all the protruding strip portions 22. Further, the surface including the chamfered portion 23 is inclined with respect to the tangent line A direction, and is inclined so as to be lowered toward the distal end portion in the axial direction.

  As shown in FIG. 2, the tube expansion device 6 using the tube expansion billet 2 configured as described above includes a plurality of heat transfer tubes 1 bent in a U-shape and through holes (not shown) provided at predetermined positions. The work holding part 61 for holding the heat exchanger 5 before completion composed of the laminated fins 4 in which the thin plates such as aluminum into which the heat transfer pipes 1 are inserted are laminated at predetermined intervals, and the expanded billet 2 is attached to the tip part. A plate 62 that rotatably holds the upper ends of a predetermined number of mandrels 3 and a hydraulic cylinder 63 as a drive mechanism that moves the plate 62 up and down in the vertical direction are provided.

  A detachable flange 31 is provided at the upper end of the mandrel 3 on the hydraulic cylinder 63 side. After the upper end of the mandrel 3 is passed through the plate 62 with the flange 31 removed, the flange 31 is Install. As a result, the mandrel 3 and the plate 62 are connected in the direction of gravity, but the mandrel 3 is locked so as to be freely rotatable in the circumferential direction together with the tube expansion billet 2. In addition, since the other structure is the same as that of the conventional pipe expansion apparatus, description is abbreviate | omitted.

  Next, the operation of the first embodiment configured as described above will be described. When the hydraulic pressure is applied to the hydraulic cylinder 63 in the state of FIG. 2, the load is transmitted to the plate 62 connected to the hydraulic cylinder 63, and the tube expansion billet 2 starts to descend together with the mandrel 3. When the lower end (expansion in the tube expansion direction) of the tube expansion billet 2 reaches the opening end of the heat transfer tube 1, the tube expansion direction tip of the ridge portion 22 is on the distal end side by the surface inclined with respect to the tangential A direction with respect to the rotation trajectory. When the chamfered portion 23 at the tip of the ridge 22 contacts the heat transfer promotion fin 11 of the heat transfer tube 1 by being obliquely chamfered so that the cut portion becomes larger, the pipe expansion billet 2 The force generated by the lowering of the pressure generates a circumferential component in addition to the reaction force in the direction opposite to the lowering direction within the contact surface.

  As the lowering of the expanded billet 2 proceeds, the expanded billet 2 rotates in the circumferential direction together with the mandrel 3, and finally, as shown in FIG. 4, the protrusion 22 of the mandrel 3 is fitted between the heat transfer promoting fins 11. Then, it enters the heat transfer tube 1. Further, when the mandrel 3 is lowered, the tube expansion billet 2 passes through the heat transfer tube 1 while expanding the heat transfer tube 1, and the outer surface of the heat transfer tube 1 is fixed to the through hole (not shown) of the laminated fin 4 by expanding the outer diameter. A vessel 5 is formed.

  The pipe expansion billet 2 of the first embodiment configured as described above expands the heat transfer promotion fin 11 in the circumferential direction while pushing only the inner circumference on the base side of the heat transfer promotion fin 11 of the heat transfer pipe 1 in the radial direction. The outer diameter of the heat transfer tube 1 can be expanded without being crushed and fixed to the through-hole provided in the laminated fin 4. For this reason, the heat-transfer performance fall of the obtained heat exchanger can be prevented. Furthermore, the tube expansion direction tip of the ridge 22 is chamfered by a surface inclined with respect to the tangential direction with respect to the rotation trajectory so that the cut portion becomes larger toward the tip, so that the tip of the ridge 22 is When the heat transfer promotion fin 11 of the heat transfer tube 1 comes into contact with the chamfered portion 23, the tube expansion billet 2 rotates in the circumferential direction. Finally, as shown in the cross-sectional view of FIG. Since they are guided and fitted in between, there is an advantage that damage to the heat transfer promotion fins 11 and the ridges 22 and breakage of the mandrel 3 connected to the pipe expansion billet 2 can be prevented.

Further, in the tube expansion device of the first embodiment, the tube expansion direction tip portion of the ridge portion 22 is chamfered so that the cut portion becomes larger toward the tip portion side by a surface inclined with respect to the tangential direction with respect to the rotation locus. The billet 2 is used, and the specific tube expansion billet 2 is rotatably supported with respect to the plate 62, thereby preventing the heat transfer promotion fins 11 of the heat transfer tube 1 from being damaged and preventing the mandrel from being broken. In addition, it is possible to obtain a remarkable effect that is not possible in the past, such as smooth production and improved yield.
Moreover, since the heat exchanger manufactured by the pipe expansion billet 2 or the pipe expansion apparatus of Embodiment 1 is the thing in which the heat transfer promotion fin 11 inside the heat transfer pipe 1 is not damaged, the effect that heat exchange performance is excellent. Is obtained.

Embodiment 2. FIG.
FIG. 5 is a perspective view of the main part showing the vicinity of the tip of the expanded billet according to the second embodiment of the present invention. In the figure, an anti-adhesion coating 24 indicated by a hatching portion is provided on each surface of at least the tip of the ridge 22, that is, on both side surfaces, top surface, tip surface, and chamfer 23 of the ridge 22. Yes. In this example, the anti-adhesion coating 24 is formed by depositing a hard film such as diamond-like carbon by a method such as chemical vapor deposition. Other configurations are the same as those of the first embodiment.

  According to the second embodiment configured as described above, there is an advantage that the wear resistance, lubricity, chemical stability, and surface smoothness of the tip of the ridge 22 can be improved. It can suppress that the base material of the heat exchanger tube 1 adheres to the protruding item | line part 22 when a front-end | tip passes the base of the heat transfer promotion fin 11 of the heat exchanger tube 1. FIG. For this reason, since the axial resistance at the time of pipe expansion can be reduced, there is an advantage that damage to the pipe expansion device can be prevented.

Embodiment 3 FIG.
FIG. 6 is a perspective view showing a tube expansion billet according to Embodiment 3 of the present invention, and FIG. 7 is a cross-sectional view showing a schematic configuration of the tube expansion billet shown in FIG. As shown in FIG. 6, the expanded billet 2 is divided into at least two parts in the plane orthogonal to the axial direction in the vicinity of the central part in the axial direction, and is supported so as to be freely rotatable in the circumferential direction with respect to the mandrel 3. Has been. In this example, the expanded billet 2 is composed of two of a first billet 2A and a second billet 2B, and is connected by a mandrel 3 that is coaxially penetrated through both axes, and the first billet 2A and the second billet 2B. When an external force that rotates in the circumferential direction is applied, the bearings are supported so that they can rotate independently of each other. The diameters of the outermost circumferences of the first billet 2A and the second billet 2B are the same.

  At the time of tube expansion, a chamfered portion 23 (not shown) similar to that of the first embodiment is provided at the distal end portion of the convex strip portion 22A of the first billet 2A that is in the distal direction. A similar chamfer may be provided. Further, as shown in the cross-sectional view of FIG. 7, a screw hole 3 a for screwing a screw 32 inserted through the shaft hole of the first billet 2 </ b> A is provided at the tip of the mandrel 3. The first billet 2A and the second billet 2B are held by the screw 32 so as not to fall off in the axial direction, and the screw hole 3a is formed so that a slight gap G is formed between the first billet 2A and the second billet 2B. The length of is set.

  According to the third embodiment configured as described above, even when the heat transfer tube 1 is twisted or meandering, the protrusion 22A of the first billet 2A and the protrusion of the second billet 2B are provided. Since the strip portion 22B is independent, it is difficult to be restrained by the roots of the heat transfer promotion fins 11 of the heat transfer tube 1 and can pass smoothly even if the pipe expansion proceeds. Moreover, since it can reduce that the axial resistance at the time of tube expansion increases, there is an advantage that damage to the tube expansion device can be prevented.

Embodiment 4 FIG.
FIG. 8 is a diagram schematically showing the external appearance of the main part of a heat exchanger according to Embodiment 4 of the present invention, where (a) is a top view and (b) is a front view. FIG. 9 is a view for explaining a heat transfer tube of the heat exchanger shown in FIG. 8, wherein (a) is a partial cross-sectional view, and (b) is a heat transfer tube expanded using a conventional tube expansion billet as a comparative example. FIG. In the figure, the heat exchanger 50 uses the pipe expansion billet 2 according to the present invention shown in the first embodiment, and allows the heat transfer pipe 1 to pass through the pipe expansion device shown in FIG. The outer surface of the heat transfer tube 1 is fixed to four through holes (not shown). As shown in FIG. 9A, the heat transfer promotion fin 11 of the heat transfer tube 1 after the tube expansion generally maintains the shape before the tube expansion including the tip shape rounded in an arc shape.

  On the other hand, when the outer surface is expanded with a spherical expansion billet or the like, as shown in the comparative example of FIG. 9B, the vicinity of the tip of the heat transfer promoting fin 11 is crushed and the height is lowered. Furthermore, the shape of the tip is also deformed from a curved surface to a trapezoidal cross section. In a heat exchanger having a cross-sectional shape of a heat transfer tube having heat transfer promoting fins, when a refrigerant consisting of a mixed flow of gas and liquid flows through the inside of the heat transfer tube, the liquid phase is affected by inertial force and gravity. Although the gas phase flows near the base of the heat transfer promotion fin and the upper part or near the center of the heat transfer tube, the heat transfer promotion fin 11 is crushed in the heat transfer tube 1 expanded by the tube expansion billet 2 of the present invention. Since the tip of the heat transfer promotion fin 11 protrudes into the gas phase, the heat path with the laminated fin 4 outside the heat transfer tube 1 is shorter than that through the liquid phase, and the heat exchange efficiency is improved. improves.

As described above, in the heat exchanger of the fourth embodiment, since the pipe is expanded using the pipe expansion billet 2 shown in the first embodiment, the heat transfer promoting fins 11 inside the heat transfer pipe 1 are expanded during the pipe expansion. The shape is maintained, and the effect of excellent heat exchange efficiency is obtained.
It should be noted that within the scope of the present invention, a part or all of each embodiment can be freely combined, or each embodiment can be appropriately modified or omitted.

  DESCRIPTION OF SYMBOLS 1 Heat transfer tube, 11 Heat transfer promotion fin, 12 Concave part, 2 Expanded billet, 2a Through hole, 2A 1st billet, 2B 2nd billet, 21 Concave groove, 22, 22A, 22B Convex strip part, 22a Corner | angular part, 22b Root Part, 23 chamfered part, 24 anti-adhesion coating, 3 mandrel, 3a screw hole, 31 flange, 32 screw, 4 laminated fin, 5, 50 heat exchanger, 6 pipe expansion device, 61 work holding part, 62 plate, 63 hydraulic pressure Cylinder, A tangent, G gap.

Claims (5)

  A pipe expansion billet used for expansion of a heat transfer tube in which a plurality of heat transfer promotion fins having a convex cross section and extending in the longitudinal direction are projected on an inner peripheral surface, and the inner periphery of the heat transfer tube between adjacent heat transfer promotion fins A plurality of protruding ridges protruding in the radial direction so as to be able to expand the heat transfer tube in contact with the surface and having a maximum outer diameter portion in the axial central portion, are formed between the adjacent protruding ridge portions, Concave grooves that receive the heat transfer promoting fins are alternately formed in the circumferential direction of the outer peripheral surface, and at the distal end side by the surface inclined with respect to the tangential direction with respect to the rotation trajectory at the distal end portion in the tube expansion direction of the protruding portion A tube expanding billet characterized in that a chamfered portion is formed so that the excised portion becomes larger.   2. The expanded billet according to claim 1, wherein the billet body is divided into a plurality of parts in the axial direction.   The tube-expanding billet according to claim 1 or 2, wherein an adhesion preventing coating is provided on at least the surface of the protruding portion in the axial direction.   The tube expansion billet comprising: the tube expansion billet according to any one of claims 1 to 3; a mandrel that holds the tube expansion billet; and a drive mechanism that moves the mandrel in the axial direction of the mandrel. Is held in a freely rotatable manner with respect to at least one of the mandrel and the drive mechanism.   The pipe is expanded by the pipe expansion billet according to any one of claims 1 to 3, and a plurality of heat transfer promotion fins protruding in the longitudinal direction with a convex cross section are projected on the inner peripheral surface, A heat exchanger comprising: a heat transfer tube that is held in a curved shape before expansion, and a laminated fin that is inserted into the through hole and fixed to each other by the expansion.

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