Tube expansion tool and tube expansion method

Abstract

To provide a tube expansion tool which holds and expands a tip of a positioned heat exchange tube, and easily pulls out a tube expansion billet after end of tube expansion.SOLUTION: A tube expansion tool 10 has a chuck sleeve 20 in which a plurality of holding pieces 20b at the tip of a cylindrical body 20a externally fit to a mandrel 18b with a tube expansion billet 18a are warped in a bow shape, and a slit 21 between the holding pieces 20b has a fan-shaped slit part 20g having a width gradually widened in a tip direction from a long hole 20e and a narrow opening 20f, and a slide sleeve 22 which contracts the width of the whole slit 21 of the chuck sleeve 20, and cylindrically restrains the respective holding pieces 20b or slides them in a release direction, wherein when the holding pieces 20b to which a tip 14a is inserted are cylindrically restrained by the slide sleeve 22 and the tube expansion billet 18a is inserted to the positioned heat exchange tube 14 and the tube is expanded, only tips of trapezoidal or triangular projecting lines 20h of inner wall surfaces of the respective holding pieces 20b bite in and hold outer peripheral surfaces without contracting the inner diameter of a tube expansion part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a tube expansion tool and a tube expansion method used for expanding a heat exchanger tube. [Background technology]

[0002] When manufacturing heat exchangers used in home room coolers, etc., a tube expansion tool is used to expand a copper heat exchange tube that penetrates a fin layer in which multiple heat dissipation fins are stacked, and to integrate the heat dissipation fins and the heat exchange tube. When expanding the heat exchange tube using the tube expansion tool, the avec phenomenon, in which the fins stick to each other, may occur due to the longitudinal shrinkage of the heat exchange tube that occurs with the tube expansion. Recently, in order to improve the thermal properties of heat exchangers and reduce their weight for energy saving and other reasons, there has been a demand for thinner copper heat exchange tubes. When thin-walled copper heat exchange tubes are expanded, they shrink more in the longitudinal direction than when normal-thickness heat exchange tubes are expanded. In addition, to reduce the weight of heat exchangers, it is desirable to use aluminum heat exchange tubes instead of copper heat exchange tubes. However, since aluminum has a lower thermal conductivity than copper, there is a demand for further thinning in order to improve the thermal properties of aluminum heat exchange tubes.

[0003] When expanding the thinned heat exchange tubes, the shrinkage of the heat exchange tubes due to the expansion can be prevented by grasping the upper end of the heat exchange tube protruding from the top plate of the fin layer and the lower end of the heat exchange tube protruding from the bottom plate, but the lower end of the heat exchange tube is not expanded and can be easily grasped with a grasping tool such as a receiver. However, it is difficult to grasp and expand the tip of the heat exchange tube to be expanded. A tube expansion tool capable of grasping the tip of such a heat exchange tube and expanding it is proposed in the following Patent Document 1.

[0004] Patent Document 1 discloses a heat transfer tube fixing device having a gripping portion that grips one axial end of a plurality of heat transfer tubes inserted into insertion holes of a plurality of heat transfer fins stacked at a predetermined interval, and a moving portion that moves in the axial direction of the heat transfer tube to switch between a first state in which the gripping portion is covered and a second state in which the gripping portion is not covered, and a mandrel device having a mandrel that is inserted into the heat transfer tube from one axial end side of the heat transfer tube, and the moving portion is a plate-shaped A heat transfer tube expanding device has been proposed, in which the mandrel is inserted into the heat transfer tube to expand the heat transfer tube while the moving part is in the first state, the gripping part fixes the heat transfer tube so as not to move in the axial direction, and the heat transfer fins and the heat transfer tube are fixed. The member provided with the gripping part is a collet chuck in which a tip end of a cylindrical body is divided to form a plurality of gripping pieces, which are curved radially outward from the cylindrical body midway, and fan-shaped slits that are gradually widened in the tip direction are opened on the tip surface between the gripping pieces, and the gripping pieces are the gripping part.

[0005] According to this heat transfer tube expanding device, a single plate-like member can simultaneously grip and expand the tips of many heat transfer tubes (called heat exchange tubes). However, in recent years, room coolers and the like have been shifting to high-mix low-volume production, and the arrangement and arrangement density of the heat exchange tubes inserted into the fin layers of the heat exchanger are frequently changed. Every time the arrangement and arrangement density of the heat exchange tubes are changed, the plate-like member must be changed to one that matches the arrangement and density of the changed heat exchange tubes, which requires a complicated replacement work. In contrast to the tube expansion jig proposed in Patent Document 1, which uses a single plate-shaped member to simultaneously grasp and expand the tip ends of multiple heat exchange tubes, Patent Documents 2 and 3 listed below propose tube expansion tools that can grasp and expand the tip end of each heat exchange tube used in a heat exchanger.

[0006] Fig. 9 shows a schematic diagram of an example of a tube expansion jig proposed in Patent Document 2. The object to be expanded by the tube expansion jig 100 shown in Fig. 9 is a heat exchange tube 104 that is inserted into a collared through-hole in a fin layer in which heat dissipation fins 102, each having a plurality of collared through-holes of a predetermined height, are stacked, and whose tip portion 104a protrudes from a top plate 106 of the fin layer. The lower ends of the heat exchange tubes 104 protruding from the bottom plate of the fin layer are held by a holding jig (not shown) such as a receiver.

[0007] The tube expansion tool 100 includes a tube expansion mandrel 108 having a mandrel 108b at the front end of which is attached a tube expansion billet 108a that expands the heat exchange tube 104 and integrates it with each of the heat dissipation fins 102, and a rear end of which is connected to a press-fitting means (not shown) that is provided so as to be movable in the direction of inserting and removing the tube expansion billet 108a into and from the heat exchange tube 104, and a cylindrical body 112a that is externally inserted onto the tube expansion mandrel 108 so as to be able to slide. A plurality of gripping pieces 112b are formed by dividing the front end of the cylindrical body 112a, and the gripping pieces 112b are arranged along the way. The slit 112c formed between the gripping pieces 112b, 112b is curved radially outwardly of the cylindrical body 112a, and is formed into a fan-shaped slit portion that gradually widens toward the tip end while leaving a narrow slit portion 112 of a predetermined length on the rear end side of the cylindrical body 112a.The gripping body 112 has an outer surface formed into an inclined surface 112e at a portion corresponding to a protrusion 112d protruding inwardly of the cylindrical body 112a formed on the inner wall surface of the gripping piece 112b, and a cylindrical body 114 that is inserted into the gripping body 112 so as to be slidable in the longitudinal direction.

[0008] In the method of expanding the heat exchange tube 104 using the tube expansion tool 100 shown in Fig. 9, the gripper 112 located above the tip 104a of the heat exchange tube 104 protruding from the top plate 106 shown in Fig. 10(a) is lowered so that its tip surface abuts against the top plate 106 as shown in Fig. 10(b), and the tip 104a of the heat exchange tube 104 is surrounded by a plurality of gripping pieces 112b of the gripper 112. Next, as shown in Fig. 10(c), the tube expansion mandrel 108 is lowered to expand the portion including the tip 104a of the heat exchange tube 104 with the tube expansion billet 108a to form the expanded portion 104b, and the descent of the tube expansion mandrel 108 is stopped. The expanded tube portion 104b and the top plate 106 are integrated together. 10(d), the cylindrical body 114 is lowered along the gripping body 112, and its tip portion rides on the inclined surface 112e of the gripping body 112, and the fan-shaped slit portion of the slit 112c is reduced in width to approximately the same width as the remaining narrow slit portion. At this time, the protruding portion 112d on the inner wall surface of the gripping piece 112b presses the expanded portion 104b to form a crimped portion 104c with a reduced diameter. The protruding portion 112d and the crimped portion 104c become the gripping portion of the heat exchange tube 104 when the descent of the tube expansion mandrel 108 is resumed to expand the heat exchange tube 104 to the lower end protruding from the fin layer of the heat exchange tube 104, and together with a gripping tool such as a receiver that grips the lower end of the heat exchange tube 104, the heat exchange tube 104 can be prevented from shrinking due to tube expansion.

[0009] Fig. 11(a) shows a schematic diagram of an example of the tube expansion tool proposed in Patent Document 3. The object to be expanded by the tube expansion tool 200 in Fig. 11(a) is, like the tube expansion tool 100 in Patent Document 2, a heat exchange tube 204 that is inserted into a collared through-hole in a fin layer in which heat dissipation fins 202 having a plurality of collared through-holes of a predetermined height are stacked, and a tip portion 204a of the heat exchange tube 204 protruding from a top plate 206 of the fin layer. The lower end portion of the heat exchange tube 204 protruding from the bottom plate of the fin layer is held by a holding tool (not shown) such as a receiver.

[0010] The tube expansion jig 200 directly contacts the outer peripheral surface of the expanded billet 208a, which is inserted from the tip 204a of the heat exchange tube 204 that penetrates the fin layer and protrudes from the top plate 206, with the inner wall surface of the heat exchange tube 204, expanding the heat exchange tube 204 and integrating it with the heat dissipation fin 202. The tube expansion jig 200 is capable of reducing its diameter by fastening force, and includes a chuck sleeve 212a in which an inner wall surface 212d at the tip protrudes inward more than the inner wall surfaces of the other parts and is formed in a thick portion 212b, and a clamp bush 214 provided slidably along the outer peripheral surface of the chuck sleeve 212a in the direction of fastening the chuck sleeve 212a or in the direction of releasing the fastening, and a recessed groove 212c is formed on the inner wall surface of the thick portion 212b of the chuck sleeve 212a. Furthermore, within the chuck sleeve 212a, a guide portion 216a is formed at the tip portion to be inserted into the tip portion of the expanded portion of the expanded heat exchange tube 204, and a flare punch 216 is formed in the middle portion to further expand the tip portion of the expanded portion to form a flared portion.The flare punch 216 is mounted so as to be slidable in the vertical direction along a mandrel 208b having an expansion billet 208a attached to its tip.

[0011] When expanding the heat exchange tube 204 as shown in Fig. 11(b) using the tube expansion tool 200 shown in Fig. 11(a), first, the front end 204a of the heat exchange tube 204, whose rear end is held by a holding tool (not shown), which protrudes after penetrating the fin layer, is inserted into the thick-walled portion 212b formed at the front end of the chuck sleeve 212a, and the clamp bush 214 is lowered to clamp the chuck sleeve 212a including the thick-walled portion 212b. At this time, the thick-walled portion 212b of the chuck sleeve 212a is also reduced in diameter, and the front end 204a of the heat exchange tube 204 is positioned in a direction in which the axis of the tube expansion billet 208a coincides with that of the tube expansion billet 208a. At this time, the tip 204a of the heat exchange tube 204 is not gripped by the thick portion 212b of the chuck sleeve 212a, and by pressing the top plate 206 with the tip surface of the chuck sleeve 212a, the length of the tip 204a of the heat exchange tube 204 protruding from the top plate 206 can be adjusted. Next, the expanded billet 208a is inserted into the tip 204a of the heat exchange tube 204 to expand it, and the outer peripheral surface of the expanded portion 204b is pressed against the inner wall surface 212d of the thick portion 212b of the chuck sleeve 212a to generate a gripping force to grip it, and then the insertion of the expanded billet 208a into the heat exchange tube 204 is temporarily stopped, and the guide portion 216a of the flare punch 216 is inserted into the expanded portion 204b. By inserting this guide portion 216a, a decrease in the gripping force caused by the diameter reduction due to the springback phenomenon of the expanded portion 204b after the passage of the expanded billet 208a is prevented. Furthermore, the expansion billet 208a is inserted again in the direction toward the rear end of the heat exchange tube 204 to expand the tube, and the heat exchange tube 204 and the heat dissipation fin 202 are integrated together. Thereafter, after the expansion of the heat exchange tube 204 is completed, the clamp bush 214 is raised to release the grip of the expanded portion 204b of the heat exchange tube by the thick portion 212b of the chuck sleeve 212a, and the chuck sleeve 212a is further raised, after which the flare punch 216 is lowered along the mandrel 208b to form a flare portion at the tip portion of the expanded portion 204b, and the expanded billet 208a is pulled out of the expanded heat exchange tube 204. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Patent No. 5696745 [Patent Document 2] Patent No. 5870418 [Patent Document 3] JP 2010-247190 A Summary of the Invention [Problem to be solved by the invention]

[0013] According to the tube expansion tool 100 of Patent Document 2 described above, the tip of each heat exchange tube 104 can be grasped to expand the heat exchange tube 104, and shrinkage of the heat exchange tube 104 due to tube expansion can be prevented as much as possible. Furthermore, since the tube expansion tool 100 is provided for each heat exchange tube 104, changes in the arrangement and arrangement density of the heat exchange tubes 104 inserted into the fin layer can be accommodated for each changed heat exchange tube 104, so that frequent changes in the arrangement and arrangement density of the heat exchange tubes 104 can be accommodated quickly. However, as shown in Fig. 10(c), the tube expansion jig 100 expands the tip 104a of the heat exchange tube 104 that is not fixed to the top plate 106 of the fin layer by lowering the tube expansion mandrel 108 and inserting the tube expansion billet 108a into the tip 104a. The tip 104a of the heat exchange tube 104 that is not fixed to the top plate 106 of the fin layer may be inclined, protruding from the top plate 106. The axial centers of the tip 104a of the heat exchange tube 104 in this inclined state and the tube expansion mandrel 108 do not coincide, and when the tube expansion mandrel 108 is lowered to insert the tube expansion billet 108a into the tip 104a of the heat exchange tube 104, the tip 104a of the heat exchange tube 104 may buckle. Even if the axial center of the tip 104a of the heat exchange tube 104 and the expansion mandrel 108 are aligned, if the tip 104a of the heat exchange tube 104 is expanded in an unfixed state, shrinkage occurs in the tip 104a. Furthermore, when the expansion billet 108a expanding the tip 104a of the heat exchange tube 104 reaches a predetermined position, the descent of the expansion mandrel 108 is temporarily stopped, the gripping body 112 is lowered to form the crimped portion 104c in the expanded portion 104b, and then the descent of the expansion mandrel 108 is resumed to resume expansion by the expansion billet 108a. In this manner, while the expansion billet 108a is expanding the heat exchange tube 104, controlling the drive means of the expansion mandrel 108 so that the descent of the expansion mandrel 108 can be stopped and resumed when the expansion billet 108a reaches a predetermined position requires a complex control means. Furthermore, when the expansion of the heat exchange tube 104 is completed and the expansion billet 108a is removed, the crimped portion 104c, which has undergone work hardening, needs to be re-expanded with the expansion billet 108a, which places an excessive load on the gripping means, such as a receiver, that grips the rear end of the heat exchange tube 104, and there is a risk that the gripping means, such as a receiver, and / or the rear end of the heat exchange tube 104 may be damaged.

[0014] The slit 112c formed in the gripping body 112 of the tube expanding jig 100 is a fan-shaped slit portion that is gradually expanded toward the tip while leaving a narrow slit portion of a predetermined length. This slit 112c is intended to expand and contract only the fan-shaped slit portion. If the narrow slit portion is also expanded or contracted, the expansion and contraction stress will be concentrated on the rear end portion 115 of the narrow slit portion, and there is a risk of cracks occurring in the rear end portion 115. When using a tube expanding jig 100 having a gripping body 112 in which such a slit 112c is formed, it is necessary to reduce the variation in the outer diameter of the expanded portion 104b of the heat exchange tube 104 as much as possible. However, in the expanded portion 104b of the heat exchange tube 104, in addition to variations in the outer diameter of the heat exchange tube 104 itself, there is also variation in the expansion, and when the fan-shaped slit portion expands and contracts to grip the expanded portion 104b with such variations by the multiple gripping pieces 112b of the gripping body 112, the narrow slit portion following the fan-shaped slit portion may also expand and contract, and the expansion and contraction stress may concentrate on the rear end portion 115 of the narrow slit portion, causing a risk of breakage. The same is true of a collet chuck with a fan-shaped slit opening at its tip surface, which is used as a member with a gripping portion formed in the heat transfer tube expanding device of Patent Document 1.

[0015] According to the tube expanding jig 200 of Patent Document 3, when inserting the expanded billet 208a into the tip 204a of the heat exchange tube 204, the tip 204a of the heat exchange tube 204 is adjusted in position by the chuck sleeve 212a in a direction in which the axis of the tip 204a coincides with that of the expanded billet 208a, so that it is possible to prevent a situation in which the expanded billet 208a is inserted into the tip 204a of the heat exchange tube 204 that is in an inclined state, as occurs with the tube expanding jig 100 of Patent Document 2. In addition, since the inner wall surface of the heat exchange tube after expansion is smooth, the expanded billet 208a can be easily pulled out of the expanded heat exchange tube.

[0016] In the tube expansion jig 200, similarly to the tube expansion jig 100, when the tip portion 204a of the heat exchange tube 204 is expanded, the insertion of the tube expansion billet 208a into the heat exchange tube 203 is temporarily stopped, and the guide portion 216a of the flare punch 216 is inserted into the tube expansion portion 204b, and then the insertion of the tube expansion billet 208a is resumed. In this manner, while the tube expansion billet 208a is expanding the heat exchange tube 104, it is necessary to control the drive means of the tube expansion mandrel 208 so that the descent of the tube expansion mandrel 208 can be stopped and resumed when the tube expansion billet 208a reaches a predetermined position, which requires a complex control means. In addition, in the expansion tool 200, the expansion section 204b of the heat exchange tube 204 is gripped by the thick portion 212b of the chuck sleeve 212a due to a gripping force generated when the outer circumferential surface of the expansion billet 208a presses the outer circumferential surface of the expansion section 204b against the inner wall surface 212d of the chuck sleeve 212a when the gap between the outer circumferential surface of the expansion billet 208a and the inner wall surface 212d of the thick portion 212b of the chuck sleeve 212a becomes minimum, as described below. In other words, the expansion of the heat exchange tube 204 by the tube expansion billet 208a is an operation of expanding the inner diameter while reducing the tube wall as the tube expansion billet 208a advances, and even if the expanded tube portion 204b has a reduced tube thickness, if the tube thickness is a predetermined thickness, the expanded tube portion 204b is pressed against the inner wall surface 212d of the chuck sleeve 212a with a predetermined pressing force from the tube expansion billet 208a to exert a predetermined gripping force in the minimum gap between the outer circumferential surface of the tube expansion billet 208a and the inner wall surface 212d of the chuck sleeve 212a. In this way, the inner wall surface 212d of the chuck sleeve 212a is pressed by the tube expansion billet 208a, so it is necessary for the inner wall surface 212d to have a strength capable of resisting the pressing force of the tube expansion billet 208a. In addition, the heat exchange tube 204 to be expanded usually has variations in tube thickness and / or outer diameter, and when expanding an expansion billet 204 in which the tube thickness is thinner and / or the outer diameter is shifted in the direction of smaller diameter, the tube thickness of the expanded portion 204b which has been expanded and reduced in thickness and reaches the minimum gap between the expansion billet 208a and the inner wall surface 212d of the chuck sleeve 212a may become less than a predetermined thickness, and the gripping force of the expanded portion 204b may suddenly decrease. For this reason, the range in which the expansion tool 200 can accommodate variations in the tube thickness and / or outer diameter of the heat exchange tube 204 is narrow. Incidentally, the groove 212c formed on the inner wall surface 212d of the chuck sleeve 212a is a clearance for the excess tube wall of the expanded portion 204b generated in the minimum gap between the outer peripheral surface of the expansion billet 208a and the inner wall surface 212d of the chuck sleeve 212a during expansion of the expansion billet 204 with a thicker tube wall and / or an outer diameter shifted in the direction of a larger diameter, as described below, and is intended to prevent damage to the chuck sleeve 212a and deformation of the expanded heat exchange tube. Therefore, in the expansion of the heat exchange tube 204 with a wall thickness and / or outer diameter that does not generate excess tube wall in the minimum gap between the expansion billet 208a and the chuck sleeve 212a, the original space is preserved in the groove 212c, and the gripping force of the expanded portion 204b is generated only by the pressing force of the expansion billet 208a against the inner wall surface 212d of the chuck sleeve 212a.

[0017] The present invention has been made to solve the above-mentioned problems, and aims to provide a tube expansion tool and a tube expansion method which, by using an expansion tool having a chuck sleeve with a slit formed therein, can adjust the position of the tip of the heat exchange tube in a direction that coincides with the axis of the expansion billet to expand it, even if the tip of an unexpanded heat exchange tube is inclined against the top plate of the fin layer, etc., and which can continuously insert the expansion billet into the heat exchange tube without stopping the insertion of the expansion billet once to complete the expansion, and which can easily remove the expanded billet from the heat exchange tube without damaging the gripping means for gripping the rear end of the heat exchange tube and the rear end of the heat exchange tube when the expansion has been completed, and which can easily and reliably grip the tip of a heat exchange tube having variations in tube wall thickness and / or outer diameter with a chuck sleeve, and which can distribute stress associated with the expansion and contraction of the slit in the chuck sleeve. [Means for solving the problem]

[0018] The tube expansion tool made to achieve the above object is a tube expansion tool that grasps and expands a heat exchange tube, the front end and rear end of which protrude from a fin layer in which a plurality of heat dissipation fins are laminated, so as to prevent longitudinal contraction of the tube, and integrates the tube with each of the heat dissipation fins by grasping the front end and rear end so as to prevent the tube from shrinking. The tube expansion tool comprises a mandrel that is inserted from the front end of the grasped heat exchange tube at the rear end, to which an expansion billet for expanding the heat exchange tube is connected at the front end, and whose rear end is connected to a press-fitting means that is provided so as to be movable in a direction in which the expansion billet is inserted and removed from the heat exchange tube, and a cylindrical body that is slidably inserted around the mandrel, and a plurality of gripping pieces formed by dividing the front end of the cylindrical body into which the front end of the heat exchange tube is inserted are curved in a bow shape toward the outer surface of the cylindrical body due to their spring force, and slits between the gripping pieces are formed in the front end of the cylindrical body. a chuck sleeve having an inner wall that opens onto the circumferential surface of the rear end side of the body and that is composed of a curved hole portion and a fan-shaped slit portion that gradually widens from an opening narrower than the lateral width of the hole portion toward the tip end of the cylindrical body, and a convex rib is formed as a convex portion protruding from each of the inner wall surfaces of the gripping pieces toward the inside of the cylindrical body; and a slide sleeve that is slidably inserted along the outer circumferential surface of the chuck sleeve and slides in a direction to fasten each of the gripping pieces against the spring force so as to contract the entire slit between the gripping pieces of the chuck sleeve and to constrain each of the gripping pieces into a cylindrical shape, or slides in a direction to release the constraining, and the cross-sectional shape of the convex rib is a trapezoid or triangular shape that gradually narrows from a base portion toward the tip end, and the protruding length of the convex rib from the inner wall surface of the gripping pieces is such that each of the gripping pieces of the chuck sleeve into which the tip end of the heat exchange tube is inserted is set to be equal to or larger than the width of the slide sleeve. Sliding of When the tube expansion billet is inserted into the tip of the heat exchange tube, which is held in a cylindrical shape by the tube expansion member and adjusted in position so that the axis of the tube expansion billet coincides with that of the tube expansion member, the tip ends of the ridges are engaged with the outer circumferential surface of the expanded tube without reducing the inner diameter of the expanded tube, and a gripping portion is formed for gripping the expanded tube of the heat exchange tube. Then, a space is formed between the entire inner wall surface of each of the gripping pieces, excluding the ridges, and the outer circumferential surface of the expanded tube. When the slide sleeve slides in a direction in which the restraint by the chuck sleeve is released, each of the gripping pieces is warped in a bow shape toward the outer surface of the cylindrical body due to the spring force, and the tip ends of the convex ribs are released from the bite of the outer circumferential surface of the expanded portion, and the grip by the gripping portion is released.It is characterized by the protruding length.

[0019] It is preferable that the hole portion constituting the slit of the chuck sleeve is an elongated hole portion, the opening of the fan-shaped slit portion formed at the tip of the elongated hole portion is narrower than the horizontal width of the elongated hole portion, and when the constraint of the gripping portion is released, the horizontal width of the elongated hole portion gradually expands in the direction of the opening, so that the stress caused by the expansion and contraction of the slit can be sufficiently distributed by the curved inner wall surface of the elongated hole portion.

[0020] The portion of the gripping piece of the chuck sleeve on which the protrusion is formed is in the outer surface direction. The cylindrical body It is preferable that the sliding sleeve is formed in a thick-walled portion that is thicker than the other portions, an inclined surface is connected to the rear end of the thick-walled portion, and the entire portion including the inclined surface and the thick-walled portion is curved in a bow shape toward the outer surface of the cylindrical body due to its spring force, so that when the sliding sleeve rides up on the thick-walled portion, each of the gripping pieces can be strongly restrained into a cylindrical shape.

[0021] When each of the gripping pieces is constrained into a cylindrical shape by the sliding sleeve, an annular ridge is formed from the ridges, so that the tip of the annular ridge bites into the outer peripheral surface of the expanded portion at the tip of the heat exchange tube in an annular shape, ensuring reliable gripping, which is preferable.

[0022] It is preferable that a plurality of the annular ridges are formed, because the tips of the plurality of annular ridges can be inserted into the outer peripheral surface of the expanded portion at the tip of the heat exchange tube to provide a more secure grip.

[0023] The height of the protrusion from the inner wall surface is 0.5 to 0.8 mm. The bite width of the tip of the protrusion is 0.01 to 0.07 mm. It is preferable that there is.

[0024] The tube expansion method achieved to achieve the above object is a method for expanding a heat exchange tube, which penetrates a fin layer having a plurality of laminated fins and has a front end and a rear end protruding from the fin layer, by gripping and expanding the front end of the heat exchange tube, the rear end of which is gripped, using the above-mentioned tube expansion tool so as to prevent longitudinal contraction of the heat exchange tube, and integrating it with each of the fins, the method comprising inserting the front end of the heat exchange tube into a plurality of gripping pieces forming the front end of the chuck sleeve constituting the tube expansion tool, and sliding the slide sleeve against the spring force of the plurality of gripping pieces of the chuck sleeve against the upper surface side of the gripping pieces. The method is characterized in that the heat exchange tube is inserted into the expansion billet, the entire slit is narrowed to constrain it into a cylindrical shape, the heat exchange tube is positioned in a direction so that its axis coincides with that of the expansion billet, and then the expansion billet is inserted into the tip of the heat exchange tube, and the tip of the ridge is inserted into the outer peripheral surface of the expanded portion without narrowing the inner diameter of the expanded portion, forming a gripping portion in which a space is formed between the entire inner wall surface of each gripping piece excluding the ridge and the outer peripheral surface of the expanded portion, and then, without stopping the expansion billet, the expansion of the heat exchange tube with the tip held by the gripping portion is continued toward the rear end of the heat exchange tube.

[0025] After the expansion of the heat exchange tube is completed, the expanded billet is pulled out from the expanded heat exchange tube held by the holding portion, and then the slide sleeve is slid from the upper surface side of the multiple holding pieces of the chuck sleeve to release the cylindrical restraint state of the multiple holding pieces, and the spring force of each of the holding pieces is used to hold the expanded billet. in The cylindrical body is curved in a bow shape toward the outside. height, The tip of the protrusion of The outer circumferential surface of the expanded portion to Eat Rather than removing the congestion, The grip by the gripping portion can be easily released. Effect of the Invention

[0026] According to the expansion tool of the present invention, the tip of an unexpanded heat exchange tube can be expanded while being positioned in a direction so that its axis coincides with that of the expansion billet, thereby preventing buckling or other problems from occurring at the tip of the heat exchange tube. In addition, since only the tip of the convex rib of the chuck sleeve bites into the outer peripheral surface to form a gripping portion without reducing the inner diameter of the expanded portion of the heat exchange tube, the heat exchange tube can be expanded continuously without stopping the expanded billet once, and once expansion is completed, the expanded billet can be easily removed from the heat exchange tube without damaging the gripping means that grips the rear end of the heat exchange tube or the rear end of the heat exchange tube. Within this gripping portion, a gap is formed between the entire inner wall surface excluding the convex ribs of the chuck sleeve and the outer peripheral surface of the expanded portion, so that even if there is variation in the tube thickness and / or outer diameter of the unexpanded heat exchange tube, this can be accommodated by the width at which the tip of the convex ribs of the chuck sleeve bites into the outer peripheral surface of the expanded portion of the heat exchange tube, making it possible to easily accommodate variations in the tube thickness and / or outer diameter of the heat exchange tube. In this way, the entire inner wall surface of the chuck sleeve, excluding the convex ribs, is not in direct contact with the outer peripheral surface of the expanded portion of the heat exchange tube, and the pressing force of the expansion billet is not received through the outer peripheral surface of the expanded portion of the heat exchange tube, making it possible to eliminate the need for solidification measures such as thickening the chuck sleeve and to reduce the weight of the chuck sleeve. Furthermore, when the gripping pieces of the chuck sleeve are constrained into a cylindrical shape by the slide sleeve or released from the constrained state, the expansion / contraction stress applied to the rear end of the slit formed between the gripping pieces of the chuck sleeve due to the expansion / contraction of the slit can be dispersed, thereby preventing the occurrence of cracks, etc. due to the concentration of the expansion / contraction stress at the rear end of the slit. [Brief description of the drawings]

[0027] [Figure 1] FIG. 2 is a partial cross-sectional view for explaining an example of a tube expansion jig to which the present invention is applied. [Diagram 2] 2 is a partial cross-sectional view illustrating a state in which a tip portion of an unexpanded heat exchange tube is inserted into a tip portion of a chuck sleeve of the tube expansion jig shown in FIG. 1. [Diagram 3] 2 is a partial cross-sectional view illustrating a state in which the tip end of the chuck sleeve is converged into a cylindrical shape by the slide sleeve of the tube expansion jig shown in FIG. 1. [Figure 4] This is a partial cross-sectional view explaining that when the tip of an unexpanded heat exchange tube inserted into the tip of the chuck sleeve of the expansion jig shown in Figure 1 is in an inclined state and the axis of the tip does not coincide with the axis of the expansion billet, the position of the tip of the heat exchange tube is adjusted. [Diagram 5] 2 is a partial cross-sectional view illustrating a state in which a portion including a tip end of an unexpanded heat exchange tube inserted into the tip end of the chuck sleeve of the tube expansion jig shown in FIG. 1 is expanded by a tube expansion billet. [Figure 6] 4 is a partial cross-sectional view illustrating a state in which a portion including a tip portion of a heat exchange tube is expanded by a tube expansion billet. FIG. [Figure 7] 4 is a partial cross-sectional view illustrating a state in which a flare portion is formed at the tip end of the expanded heat exchange tube. FIG. [Figure 8] 13 is a partial front view illustrating another example of a slide sleeve to which the present invention is applied. FIG. [Figure 9] FIG. 11 is a partial cross-sectional view illustrating a conventional pipe expansion jig. [Figure 10] FIG. 10 is a partial cross-sectional view illustrating a pipe expanding method using the conventional pipe expanding jig shown in FIG. [Figure 11] FIG. 11 is a partial cross-sectional view illustrating a conventional pipe expansion jig. [Figure 12] 12 is a partial cross-sectional view illustrating a gripping portion formed by the conventional tube expanding jig shown in FIG. 11. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The present invention will be described in detail below, but the scope of the present invention is not limited thereto.

[0029] An example of a tube expansion tool to which the present invention is applied is shown in FIG. 1(a). The tube expansion tool 10 shown in FIG. 1(a) is attached to a tube expansion machine dedicated to expanding heat exchange tubes. The tube expansion tool 10 expands a heat exchange tube 14 that is inserted into a collared through hole in a fin layer 17 in which a plurality of heat dissipation fins 12 having collared through holes of a predetermined height are stacked, and a tip portion 14a of the heat exchange tube 14 protrudes from a top plate 16 of the fin layer 17. A straight tube or a hairpin tube is usually used as the heat exchange tube 14. In the case of a straight tube, the lower end protrudes from the bottom plate of the fin layer 17, and in the case of a hairpin tube, a U-shaped portion protrudes from the bottom plate of the fin layer. The protruding portion protruding from the bottom plate of the fin layer 17 is held by a holding tool (not shown) such as a receiver.

[0030] The tube expansion tool 10 is composed of an expansion mandrel 18 having a mandrel 18b, the front end of which is fitted with an expansion billet 18a that is inserted from the front end of the heat exchange tube 14 to expand the heat exchange tube 14 and become integrated with each of the heat dissipation fins 12, and a rear end of which is connected to a press-fitting means (not shown) that is provided so as to be movable in the direction of inserting and removing the expansion billet 18a into and from the heat exchange tube 14, a chuck sleeve 20 that is slidably fitted onto the expansion mandrel 18, and a slide sleeve 22 that is slidably fitted onto the chuck sleeve 20. FIG. 1(b) shows an enlarged partial cross-sectional view of the chuck sleeve 20. The chuck sleeve 20 is a cylindrical body 20a that is slidably fitted onto the mandrel 18b of the tube expansion mandrel 18, and the front end of the cylindrical body 20a is equally divided into a plurality of gripping pieces 20b. The grip piece 20b has a thick portion 20c formed on its tip side that bulges outward from the cylindrical body 20a and is thicker than the other portions, and an inclined surface 20d is formed between the main body side of the grip piece 20b and the thick portion 20c. The grip piece 20b, including the thick portion 20c and the inclined surface 20d, is curved in a bow shape toward the outer surface of the cylindrical body 20a due to its spring force. The spring force of the grip piece 20b is obtained by heat treatment of the grip piece 20b as described below.

[0031] Between the gripping pieces 20b, 20b that are bowed toward the outer surface of the cylindrical body 20a, a slit 21 is formed on the circumferential surface of the cylindrical body 20a, which is made up of a long hole portion 20e with a curved inner wall that opens in the longitudinal direction of the cylindrical body 20a, an opening portion 20f formed at the tip of the long hole portion 20e and narrower than the width of the long hole portion 20e, and a fan-shaped slit portion 20g that gradually widens from the opening portion 20f toward the tip of the cylindrical body 20a. The long hole portion 20e also gradually widens in the direction of the opening portion 20f, but the width is narrow at the opening portion 20f. Furthermore, a plurality of protruding stripes 20h that protrude inward of the cylindrical body 20a are formed on each inner wall surface 20ci corresponding to the thick portion 20c of the gripping piece 20b. As shown in the partially enlarged cross-sectional view of Figure 1 (b), the cross-sectional shape of this convex rib 20h is a trapezoid or triangular shape that gradually narrows from the base toward the tip, and it is preferable that the height of the convex rib 20h from the inner wall surface 20ci is 0.5 to 0.8 mm.

[0032] A slide sleeve 22 is fitted onto the chuck sleeve 20 so as to be slidable along its outer circumferential surface. When the slide sleeve 22 slides downward and rides on the thick portions 20c of the gripping pieces 20b of the chuck sleeve 20 against the spring forces of the gripping pieces 20b of the chuck sleeve 20 as shown in FIG. 1(c), the entire slit 21 consisting of the elongated hole portion 20e, the opening 20f, and the sectorial slit portion 20g including the elongated hole portion 20e is contracted to clamp each of the gripping pieces 20b into a cylindrical shape. When each of the gripping pieces 20b is clamped into a cylindrical shape, the elongated hole portion 20e is contracted to become an elongated hole slit portion 23a with a constant width, and the opening 20f and the sectorial slit portion 20g are also reduced to become a narrow slit portion 23c with the same width as the narrow opening portion 23b narrower than the width of the elongated hole slit portion 23a. The elongated slit portion 23a and the narrow slit portion 23c having the same width as the narrow opening portion 23b constitute the slit 23. In addition, the multiple ridges 20h formed on the inner wall surface of each gripping piece 20b form multiple annular ridges 20H. The cross-sectional shape of the annular ridges 20H is also trapezoidal or triangular, gradually narrowing from the base to the tip.

[0033] When the slide sleeve 22, which had been constraining each of the gripping pieces 20b into a cylindrical shape as shown in FIG. 1(c), is slid upward as shown in FIG. 1(b), the state in which each of the gripping pieces 20b was constrained into a cylindrical shape is released, and each of the gripping pieces 20b is warped toward the outer surface of the cylindrical body 20a due to its spring force as shown in FIG. 1(b), and the elongated slit portion 23a, narrow opening portion 23b, and narrow slit portion 23c constituting the slit 23 shown in FIG. 1(c) are each widened, and the elongated hole portion 20e shown in FIG. 1(b) is gradually widened toward the opening 20f, the opening 20f is wider than the narrow opening 23b, and the narrow slit portion 23c becomes a fan-shaped slit portion 20g which gradually widens from the opening 20f toward the tip of the cylindrical body 20a, thereby forming the slit 21.

[0034] When the gripping pieces 20b of the chuck sleeve 20 are constrained into a cylindrical shape by the slide sleeve 22, the slit 21 between the gripping pieces 20b of the chuck sleeve 20 is in a state consisting of the long hole slit portion 23a, the narrow opening portion 23b, and the narrow slit portion 23c as shown in Fig. 1(c), and when this constrain is released, it is in a state consisting of the long hole portion 20e, the opening portion 20f, and the fan-shaped slit portion 20g as shown in Fig. 1(b). In this way, the entire slit 21 formed between the gripping pieces 20b is expanded and contracted when the gripping pieces 20b are constrained into a cylindrical shape and when the constrain is released. Therefore, the expansion and contraction stress accompanying the expansion and contraction of the entire slit 21 is applied to the rear end of the long hole portion 20e (long hole slit portion 23a), but the expansion and contraction stress is dispersed by the curved inner wall at the rear end of the long hole portion 20e (long hole slit portion 23a), and the risk of cracks occurring due to stress concentration as in the collet chuck of Patent Document 1 and the gripping body of Patent Document 2 in which only fan-shaped slits are formed can be eliminated. The chuck sleeve 20 of the tube expansion jig 10 shown in Fig. 1 can be manufactured by grinding, and the gripping piece 20b formed by grinding is given springiness by applying heat treatment, and the gripping piece 20b can be warped outward from the cylindrical body 20a by its own spring force. This spring force can be made large by forming the long hole slit portion 23a.

[0035] Using the tube expanding tool 10 shown in Fig. 1, the heat exchange tube 14 is inserted into the through hole formed by the collared through hole in the fin layer 17 in which a plurality of heat dissipation fins 12 having a collared through hole of a predetermined height are laminated, and the tip portion 14a of the heat exchange tube 14 protrudes from the top plate 16 of the fin layer 17. First, as shown in Fig. 2(a), the tip surface of the gripping piece 20b of the chuck sleeve 20, in which the tip portion 14a of the heat exchange tube 14 is inserted into the gripping piece 20b, is abutted against the top plate 16 of the fin layer 17, and the tip portion 14a of the heat exchange tube 14 protrudes from the top plate 16 by a predetermined length. This is because the heat exchange tube 14 inserted into the collared through hole in the fin layer 17 is not integrated with the top plate 16 and the heat dissipation fin 12 as shown in Fig. 2(b), and the tip portion 14a of the heat exchange tube 14 may not protrude from the top plate 16 by a predetermined length.

[0036] Next, as shown in Fig. 3(a), the slide sleeve 22 slides over the inclined surface 20d against the spring force of each of the arched gripping pieces 20b of the chuck sleeve 20 and onto the thick-walled portion 20c, thereby constraining each of the gripping pieces 20b into a cylindrical shape. The slits 21 between the gripping pieces 20b constrained into a cylindrical shape are entirely narrowed, the fan-shaped slit portion 20g becomes a narrow-width slit portion 23c, and the ridges 20h formed on the inner wall surfaces of the gripping pieces 20b form annular ridges 20H as shown in Fig. 3(b). The multiple annular ridges 20H are located near the tip of the tip portion 14a of the heat exchange tube 14, and when the axis of the tip portion 14a of the heat exchange tube 14 and the axis of the expanded billet 18a are aligned, the tip of the annular ridge 20H is close to the outer circumferential surface of the tip portion 14a as shown in Fig. 3(b).

[0037] However, as shown in Fig. 2, when the tip 14a of the heat exchange tube 14 is inserted into the gripping piece 20b of the chuck sleeve 20, the heat exchange tube 14 is not fixed to the top plate 16 of the fin layer 17 and the heat dissipation fin 12, and as shown in Fig. 4(a), the tip 14a of the heat exchange tube 14 inserted into the gripping piece 20b is inclined, and the axis of the tip 14a and the expanded billet 18a may not coincide. If the expanded billet 18a is inserted into the tip 14a of the heat exchange tube 14 in such a state, the tip 14a may buckle. In this regard, according to the tube expansion jig 10 shown in Fig. 1, the gripping piece 20b of the chuck sleeve 20 is constrained into a cylindrical shape by the slide sleeve 22, as shown in Fig. 4(b), so that the position of the inclined tip 14a can be adjusted in a direction that coincides with the axis of the expanded billet 18a.

[0038] In this manner, with the axial centers of the front end 14a of the heat exchange tube 14 and the expansion billet 18a aligned, the expansion billet 18a is inserted into the front end 14a as shown in Fig. 5 to start tube expansion. As shown in Fig. 6, which is a partially enlarged view, the outer peripheral surface of the expansion portion 14b immediately after the start of tube expansion is pressed against and integrated with the inner wall surfaces of the through hole of the top plate 16 forming the fin layer 17 and the collared through hole of the heat dissipation fin 12. Furthermore, at the front end of the expansion portion 14b of the heat exchange tube 14, as shown in the partially enlarged cross-sectional view, the tip portions of the multiple annular ridges 20H formed on each inner wall surface 20ci corresponding to the thick portion 20c of the gripping piece 20b bite into the outer peripheral surface of the expansion portion 14b without reducing the inner diameter of the expansion portion 14b, forming a gripping portion. In this way, the gripping piece 20b of the chuck sleeve 20 only has the tip of its annular ridge 20H biting into the outer circumferential surface of the expanded tube portion 14b, and the inner wall surface 20ci of the thick-walled portion 20c excluding the annular ridge 20H does not contact the outer circumferential surface of the expanded tube portion 14b, and a space portion 20k is formed between the inner wall surface 20ci and the outer circumferential surface of the expanded tube portion 14b. The distance L between the point where the tip of the most distal annular ridge 20H bites into and the tip of the expanded tube portion 14b is preferably about 2 to 3 mm. In addition, the bite width t of the tip of the annular ridge 20H is preferably adjusted to be 0.01 mm or more, about 0.05 to 0.07 mm. If the bite width t of the tip of the annular ridge 20H is less than 0.01 mm, the expansion tends to be insufficient due to the springback phenomenon of the expanded portion 14b after the expansion billet 18a passes through, and if the bite width t exceeds 0.07 mm, the insertion pressure of the expansion billet 18a into the tip 14a tends to increase suddenly. This gripping portion can be formed while the heat exchange tube 14 is being continuously expanded without stopping the expansion billet 18a inserted into the tip 14a of the heat exchange tube 14, and shrinkage of the heat exchange tube 14 due to expansion can be prevented.

[0039] As shown in FIG. 6, the inner wall surface 20ci of the gripping piece 20b of the chuck sleeve 20 is not in contact with the outer circumferential surface of the expanded portion 14b, and a space 20k is formed between the inner wall surface 20ci and the outer circumferential surface of the expanded portion 14b. Therefore, even if there is a variation in the tube wall thickness and / or outer diameter of the heat exchange tube 14 to be expanded, it can be easily dealt with by increasing or decreasing the bite width t of the tip of the annular ridge 20H. For example, even if the tube wall thickness and / or outer diameter of the heat exchange tube 14 varies in a direction thicker than the median value of the variation and / or in a direction toward a larger diameter, it can be dealt with by increasing the bite width t of the tip of the annular ridge 20H to t', as shown in the partially enlarged view of FIG. 6. On the other hand, even if the tube wall thickness and / or outer diameter of the heat exchange tube 14 varies in a direction thinner than the median value of the variation and / or in a direction toward a smaller diameter, it can be dealt with by decreasing the bite width t of the tip of the annular ridge 20H.

[0040] When the expansion billet 18a reaches the lower end protruding portion of the heat exchange tube 14 protruding from the lowest plate of the fin layer 17, the expansion by the expansion billet 18a ends. In this way, the expansion tool 10 shown in Fig. 1 to Fig. 6 allows the heat exchange tube 14 to be continuously expanded without stopping the expansion billet 18a. Furthermore, when the expanded billet 18a is extracted from the expanded heat exchange tube 14, the inner diameter of the gripping portion of the heat exchange tube 14 is not reduced, so the expanded billet 18a can be extracted smoothly, and excessive load is not applied to the gripping tool such as a receiver that grips the lower end of the expansion billet 18a and the heat exchange tube 14. This also eliminates the risk of damage to the holding jig, such as a receiver, and / or the lower end of the heat exchange tube 14, which may occur when excessive load is applied to the holding jig, such as a receiver, that holds the lower end of the heat exchange tube 14 when the expanded billet 18a is removed from the expanded heat exchange tube 14. Then, the slide sleeve 22 is slid to release the constraint that holds the gripping piece 20b of the chuck sleeve 20 in a cylindrical shape, and the spring force of the gripping piece 20b causes it to bend in a bow shape outwardly from the cylindrical body 20a, releasing the engagement of the tip of the annular ridge 20H with the outer peripheral surface of the expansion portion 14b, allowing the expansion jig 10 to be moved upward from the fin layer 17.

[0041] After the tube expansion is completed, the fin layer 17 integrated with the expanded heat exchange tube is removed from the tube expansion machine, and a flare portion forming device forms a flare portion 15a at the tip portion of the expanded heat exchange tube 15 protruding from the top plate 16 of the fin layer 17 of the expanded heat exchange tube 15 as shown in Fig. 7. An end portion of a connecting tube 30 to be connected to another expanded heat exchange tube 15 is inserted into the flare portion 15a and brazed 31 is performed. A biting groove 24 is formed at the tip portion of the annular protrusion 20H formed on the gripping piece 20b of the chuck sleeve 20 on the outer circumferential surface corresponding to the location of the brazing 31 of the flare portion 15a, but the biting groove 24 is reinforced by the brazing 31, and the strength of the flare portion 15a is not reduced by the biting groove 24.

[0042] In recent years, in the production of heat exchangers such as room coolers, which are produced in small quantities and in a wide variety of products, it is desirable to improve production efficiency by minimizing the need for part replacement in the tube expansion machine. There is also a demand for tube expansion tools that can handle the expansion of heat exchanger tubes with slightly different tube diameters or walls. When the tube expanding tool 10 shown in Figs. 1 to 7 is used to hold and expand heat exchange tubes having different tube diameters or walls, when the gripping pieces 20b of the chuck sleeve 20 into which the tip ends of the heat exchange tubes having different tube diameters or walls are inserted are constrained into a cylindrical shape as shown in Figs. 5 and 6, an excessive force may act on the slide sleeve 22, causing the slide sleeve 22 to deform. This risk can be eliminated by forming a round hole 22a, which is a hole with a curved inner wall surface and is opened in the middle of the chuck sleeve 20 as shown in Fig. 8, and a narrow slit portion 22b, which is narrower than the round hole 22a, in the direction from the opening formed in the round hole 22a toward the tip end, thereby adding springiness to the chuck sleeve 20. The tube expanding tool using the chuck sleeve 20 shown in Fig. 8 can also be used to expand heat exchange tubes having large variations in tube wall thickness and / or outer diameter.

[0043] 1 to 7, multiple annular ridges 20H are formed on the expanded portion 14b of the heat exchange tube 14, but a single annular ridge 20H may be used. Alternatively, one or multiple projections may be formed on each inner wall surface of the gripping pieces 20b of the chuck sleeve 20, and the projection tips may be fitted into the outer circumferential surface of the expanded portion 14b. In addition, the flared portion 15a of the expanded heat exchange tube 15 is formed by a flare forming device separate from the tube expanding machine, but a flare punch may be provided in the tube expanding machine that expands the heat exchange tube 14, and the flare portion 15a may be formed at the tip of the expanded heat exchange tube 15 after the tube expansion is completed. Furthermore, the tube expansion tool shown in Figs. 1 to 7 is used to expand the heat exchange tubes inserted into the vertical fin layer, but may also be used to expand the heat exchange tubes inserted into the horizontal fin layer.

[0044] Now, the expansion of a heat exchange tube 204 when a chuck sleeve 212a having a recessed groove 212c formed on an inner wall surface 212d of a thick portion 212b constituting a tube expansion jig 200 shown in Fig. 11 is used instead of the chuck sleeve 20 having a plurality of annular ridges 20H formed on an inner wall surface corresponding to the thick portion 20c of the gripping piece 20b shown in Fig. 1 will be described with reference to Fig. 12. In the tube expansion billet 208a and the chuck sleeve 212a shown in Fig. 12, the minimum gap D between the outer peripheral surface which is the maximum outer diameter R of the tube expansion billet 208a and the inner wall surface 212d of the thick portion 212b of the chuck sleeve 212a is usually adjusted based on the median value of the variation in the tube thickness and / or outer diameter of the heat exchange tube 204 to be expanded.

[0045] Fig. 12(a) shows a case where a heat exchange tube 204 having a wall thickness and / or an outer diameter close to the center of variation is expanded. As shown in Fig. 12(a1), the heat exchange tube 204 is inserted into the chuck sleeve 212a, and the outer circumferential surface of the heat exchange tube 204 is close to the inner wall surface 212d of the thick-walled portion 212b. As the expansion billet 208a, which is inserted as shown in Fig. 12(a2) into the tip 204a of the heat exchange tube 204, advances, the tip 204a expands in inner diameter while reducing the wall thickness, but before being pressed by the outer circumferential surface of the maximum outer diameter R of the expansion billet 208a, the outer circumferential surface of the expansion portion 204b does not abut against the inner wall surface 212d of the chuck sleeve 212a. As the insertion of the tube expansion billet 208a progresses, as shown in the partially enlarged cross-sectional view of Fig. 12(a3), when the tube expansion billet 208a reaches the minimum gap D between the outer peripheral surface of the maximum outer diameter R and the inner wall surface 212d of the chuck sleeve 212a, the outer peripheral surface of the tube expansion portion 204b comes into contact with the inner wall surface 212d of the chuck sleeve 212a by the outer peripheral surface of the maximum outer diameter R of the tube expansion billet 208a, and is pressed and gripped with a predetermined pressing force. At this time, the minimum gap D between the outer peripheral surface of the maximum outer diameter R of the tube expansion billet 208a and the inner wall surface 212d of the chuck sleeve 212a becomes approximately equal to the pipe wall thickness of the expanded tube portion 204b that has been expanded and reduced in thickness, so that no excess pipe wall is generated in the expanded tube portion 204b, and the space of the recessed groove 212c is maintained as it is. Here, when expanding a heat exchange tube 204 that has shifted from the median of the variation in the direction of thinner tube thickness and / or smaller outer diameter, when the expanded billet 208a reaches the minimum gap D between the outer peripheral surface of its maximum outer diameter R and the inner wall surface 212d of the chuck sleeve 212a, the thickness of the expanded portion 204b may be reduced below a predetermined thickness. In such a case, the pressing force of the outer peripheral surface of the maximum outer diameter R of the expanded billet 208a pressing the inner wall surface 212d of the chuck sleeve 212a via the outer peripheral surface of the expanded portion 204b may decrease, resulting in a decrease in gripping force. Therefore, when a chuck sleeve 212a having a groove 212c formed on an inner wall surface 212d of a thick-walled portion 212b shown in FIG. 11 is used instead of the chuck sleeve 20 shown in FIG. 1, the range that can be accommodated for heat exchanger tubes whose wall thickness has shifted from the median value of variation toward a thinner tube thickness and / or a smaller outer diameter is narrow.

[0046] On the other hand, Fig. 12(b) shows a case where a heat exchange tube 204 having a wall thickness thicker than the median of the variation is expanded. As shown in Fig. 12(b1), the expansion billet 208a inserted into the tip 204a of the heat exchange tube 204 inserted into the chuck sleeve 212a expands the inner diameter while reducing the wall thickness of the tip 204a as shown in Fig. 12(b2). The outer peripheral surface of the expanded tube portion 204b is abutted against the inner wall surface 212d of the chuck sleeve 212a and pressed against it, and is further reduced toward the minimum gap D before the outer peripheral surface of the maximum outer diameter R of the expansion billet 208a reaches the minimum gap D with the inner wall surface 212d of the chuck sleeve 212a. The reduced tube wall is located at the tip end side of the tube expansion billet 208a, and a tube wall surplus 204c is generated between the heat exchange tube 204 and the inner wall surface 212d of the chuck sleeve 212a. If the tube expansion is continued while leaving this tube wall surplus 204c, there is a risk that the chuck sleeve 212a will be damaged due to excessive pressing force and / or the heat exchange tube 204 will be deformed near the lower end surface of the chuck sleeve 212a. For this reason, as shown in FIG. 12(b3) and its enlarged partial cross-sectional view, the tube wall surplus 204c is allowed to escape into the recessed groove 212c to prevent excessive pressing force from being applied to the chuck sleeve 212a and deformation of the heat exchange tube 204.

[0047] As shown in Fig. 12(b3), when the excess tube wall 204c is released into the groove 212c, a protrusion is formed on the outer peripheral surface of the expanded tube portion 204b, which, together with the pressing force against the inner wall surface 212d of the chuck sleeve 212a, can reliably hold the expanded tube portion 204b against tension. For this reason, even in the case of expanding a heat exchange tube 204 in which the tube wall thickness is thinner than the median value of the center value of the variation and / or the outer diameter is shifted in a direction to become smaller, it is considered that forming a protrusion on the outer peripheral surface of the expanded tube portion 204b by releasing the excess tube wall 204c into the groove 212c as shown in Fig. 12(b3) may be effective in holding the expanded tube portion 204b against tension. However, if the minimum gap D between the maximum outer diameter R of the expansion billet 208a and the inner wall surface 212d of the chuck sleeve 212a is adjusted so that a tube wall excess 204c occurs even when expanding a heat exchange tube 204 whose tube wall thickness is thinner and / or whose outer diameter is shifted in the direction toward a smaller diameter than the median of variation, when a heat exchange tube 204 whose tube wall thickness is thicker and / or whose outer diameter is shifted in the direction toward a larger diameter than the median of variation is expanded, excessive tube wall excess 204c occurs near the minimum gap D, and therefore excessive tube wall excess 204c occurs on the inner wall surface 212d of the chuck sleeve 212a. If a large groove 212c is formed as a clearance for such excessive pipe wall excess 204c, the strength of the chuck sleeve 212a will decrease, and therefore it will be necessary to thicken the chuck sleeve 212a and the clamp bush 214 in order to maintain the strength, which may result in the pipe expansion jig becoming larger and heavier. [Industrial Applicability]

[0048] The tube expansion jig of the present invention can be used in the manufacture of heat exchangers used in home room coolers and the like. [Explanation of symbols]

[0049] 10, 100, 200: tube expansion jig, 12, 102, 202: heat dissipation fin, 14, 104, 204: heat exchange tube, 14a, 104a, 204a: tip portion, 14b, 104b, 204b: tube expansion portion, 15: tube expansion heat exchange tube, 15a: flare portion, 16, 106, 206: top plate, 17: fin layer, 18, 108: tube expansion mandrel , 18a, 108a, 208a: tube expansion billet, 18b, 108b, 208b: mandrel, 20: chuck sleeve, 20h: ridge, 20H: annular ridge, 20a, 112a: cylindrical body, 20b: gripping piece, 20c: thick wall portion, 20ci: inner wall surface, 20d: inclined surface, 20e: long hole portion, 20f: opening, 20g: fan-shaped slit portion, 20k: space portion, 21, 23, 112c: slit, 22: slide sleeve, 22a: round hole, 22b: narrow slit portion, 23a: long hole slit portion, 23b: narrow opening, 23c: narrow slit portion, 24: biting groove, 30: connecting tube, 31: brazing, 104c: crimping portion, 112: gripping body, 112b: gripping piece, 112d: protruding portion, 112e: inclined surface, 114: cylindrical body, 115: rear end portion of narrow slit portion constituting slit 112c, 204c: excess material, 212a: chuck sleeve, 212b: thick portion, 212c: concave groove, 212d: inner wall surface of thick portion 212b, 214: clamp bush, 216: flare punch, t, t′: biting width, D: minimum gap, L: distance, R: maximum outer diameter

Claims

1. A tube expansion tool for a heat exchange tube that penetrates a fin layer in which a plurality of heat dissipation fins are laminated, and whose front and rear ends protrude from the fin layer, is gripped and expanded by the front and rear ends so as to prevent the tube from shrinking in the longitudinal direction, and is integrated with each of the heat dissipation fins, a mandrel having a rear end connected to a press-fitting means provided so as to be movable in a direction for inserting and removing the expansion billet into and from the heat exchange tube; a chuck sleeve comprising a cylindrical body slidably fitted onto the mandrel, a plurality of gripping pieces formed by dividing a tip end of the cylindrical body into which the tip ends of the heat exchange tubes are inserted, the gripping pieces being curved in a bow shape toward the outer surface of the cylindrical body due to their spring force, slits between the gripping pieces being formed with a hole portion having a curved inner wall opening onto the circumferential surface of the rear end side of the cylindrical body, and a fan-shaped slit portion which gradually widens from an opening narrower than the width of the hole toward the tip end of the cylindrical body, and a protrusion formed as a protrusion protruding inwardly from each of the inner wall surfaces of the gripping pieces; A slide sleeve is slidably inserted along the outer circumferential surface of the chuck sleeve, and slides in a direction to fasten each of the gripping pieces against the spring force so as to narrow the entire slit between the gripping pieces of the chuck sleeve and to constrain each of the gripping pieces into a cylindrical shape, or slides in a direction to release the constraining, The cross-sectional shape of the convex strip is a trapezoid or a triangle that gradually narrows from the base toward the tip, a projection length of the ridge from the inner wall surface of the gripping piece such that, when each of the gripping pieces of the chuck sleeve into which the tip of the heat exchange tube is inserted is restrained into a cylindrical shape by the sliding of the slide sleeve, and the expansion billet is inserted into the tip of the heat exchange tube positioned in a direction aligned with the axis of the expansion billet, each of the tip of the ridge bites into the outer peripheral surface of the expanded portion without reducing the inner diameter of the expanded portion, forming a gripping portion that grips the expanded portion of the heat exchange tube, a space is formed between the entire surface of each inner wall surface of the gripping pieces excluding the ridge and the outer peripheral surface of the expanded portion, and when the slide sleeve slides in a direction that releases the restraint by the chuck sleeve, each of the gripping pieces bends in a bow shape toward the outer surface of the cylindrical body due to the spring force, so that the tip of each of the ridges disengages from the bite into the outer peripheral surface of the expanded portion and the gripping by the gripping portion is released.

2. The tube expansion jig described in claim 1, characterized in that the hole portion constituting the slit of the chuck sleeve is a long hole portion, the opening of the fan-shaped slit portion formed at the tip of the long hole portion is narrower than the horizontal width of the long hole portion, and when the constraint of the gripping portion is released, the horizontal width of the long hole portion gradually expands in the direction of the opening.

3. The tube expansion tool described in claim 1, characterized in that the portion of the gripping piece of the chuck sleeve on which the convex rib is formed is formed in a thick portion that is thicker than other portions of the cylindrical body in the outer surface direction, an inclined surface is connected to the rear end of the thick portion, and the entire portion including the inclined surface and the thick portion is bow-shaped toward the outer surface direction of the cylindrical body due to its spring force.

4. 2. A pipe expansion jig according to claim 1, wherein an annular ridge is formed from the ridges when each of the gripping pieces is constrained into a cylindrical shape by the slide sleeve.

5. The pipe expansion jig according to claim 4, characterized in that a plurality of the annular ridges are formed.

6. The tube expansion jig according to claim 1, characterized in that the height of the ridge from the inner wall surface is 0.5 to 0.8 mm, and the bite width of the tip of the ridge is 0.01 to 0.07 mm.

7. A method for expanding a heat exchange tube, the heat exchange tube penetrating a fin layer in which a plurality of fins are stacked, the front end and the rear end protruding from the fin layer, the rear end of the heat exchange tube being gripped so as to prevent the heat exchange tube from shrinking in the longitudinal direction, the front end of the heat exchange tube being gripped and expanded by the tube expansion tool according to claim 1, and the heat exchange tube being integrated with each of the fins, inserting a tip end of the heat exchange tube into a plurality of gripping pieces that form a tip end of the chuck sleeve constituting the tube expansion jig; The slide sleeve is slid toward the upper surface of the gripping pieces against the spring force of the multiple gripping pieces of the chuck sleeve, the entire slit is contracted in width and constrained into a cylindrical shape, and the heat exchange tube is positioned in a direction in which the axis of the heat exchange tube coincides with that of the expanded billet. the tip end of the ridge is inserted into the outer circumferential surface of the expanded portion by inserting the expansion billet into the tip end of the heat exchange tube to expand the tube, without reducing the inner diameter of the expanded portion, thereby forming a gripping portion in which a space is formed between the entire surface of each inner wall surface of the gripping pieces excluding the ridge and the outer circumferential surface of the expanded portion; A method for expanding a heat exchange tube, characterized in that the expansion of the heat exchange tube, the tip of which is held by the holding portion, is continued in the direction toward the rear end of the heat exchange tube without stopping the expansion billet.

8. After the expansion of the heat exchange tube is completed, the expanded billet is pulled out from the expanded heat exchange tube held by the holding portion. Next, the slide sleeve is slid from the upper surface side of the multiple gripping pieces of the chuck sleeve to release the cylindrical restraint state of the multiple gripping pieces, and the spring force of each of the gripping pieces causes them to bend in a bow shape toward the outside of the cylindrical body, thereby releasing the gripping by the gripping portions by releasing the engagement of the tip ends of the convex ribs with the outer peripheral surface of the expansion portion.

Images