JP4759226B2 - Tube expansion tool and tube expansion method using the same - Google Patents

Description

  The present invention relates to a tube expansion tool used for expanding the diameter of a metal tube used in a heat exchanger and a tube expansion method using the same in the production of a plate fin tube type heat exchanger used in an air conditioner and a refrigeration air conditioner. In particular, the present invention relates to a tube expansion tool used for expanding the diameter of an internally grooved tube having a large number of grooves and fins formed between the grooves, and a tube expansion method using the same.

  Conventionally, the manufacture of a heat exchanger and the expansion work of a metal tube (inner grooved tube) at that time have been performed as follows. As shown in FIG. 8, the tube expansion tool 30 includes a tube expansion burette 32 having an outer peripheral surface larger than the inner diameter of the inner grooved tube 1 and a mandrel 31 connected to the rear end portion of the tube expansion burette 32. First, the inner grooved tube 1 is inserted into the through holes 11a of the fin plates 11 arranged in parallel. Next, the pipe expanding tool 30 is press-fitted into the inner grooved pipe 1. As a result, the inner grooved tube 1 is expanded, the clearance C between the inner grooved tube 1 and the fin plate 11 is eliminated, and the adhesion between the inner grooved tube 1 and the fin plate 11 is enhanced. Next, the tube expansion tool 30 is taken out from the inner grooved tube 1. As a result, a heat exchanger in which the inner grooved tube 1 and the fin plate 11 are joined without a gap is manufactured.

  And along with higher performance (COP improvement) and lower cost of air conditioners, inner grooved pipes for heat exchangers are required to have higher performance and lighter weight, and the groove shape has high leads, high fins, slim fins. It is becoming. In such an internally grooved tube having a groove shape that is formed into a high lead, high fin, and slim fin, when expanding the internally grooved tube, as shown in FIG. 8, the radius R of the outer peripheral surface 32a of the expanded bullet 32 is shown. Is small, the outer diameter of the internally grooved tube 1 is rapidly expanded. As a result, the frictional force between the fin 3 of the internally grooved tube 1 and the expanded burette 32 is increased, the fin 3 is likely to be deformed, and the heat transfer performance of the internally grooved tube (heat exchanger) is reduced. there were.

  In addition, as an inner grooved tube in which a high-pressure refrigerant such as carbon dioxide gas is used, an inner grooved tube having a thick wall has begun to be used. In such an internally grooved tube, the bottom wall thickness of the tube becomes thick, and when the heat exchanger is manufactured, the expansion load of the internally grooved tube becomes excessive, and the fin on the inner surface of the tube is extremely deformed. As a result, there has been a problem that the heat transfer performance of the internally grooved tube (heat exchanger) decreases.

  In order to solve the deformation of the fin on the inner surface of the pipe as described above, it is proposed in Patent Document 1 to specify the groove shape of the inner grooved pipe. That is, in Patent Document 1, the inner grooved tube is manufactured so that the inclination of the fin formed on the inner surface of the inner grooved tube is substantially perpendicular to the inner surface of the tube.

Further, Patent Document 2 proposes improving the method of expanding the inner grooved tube. That is, in Patent Document 2, when expanding the inner grooved tube, a tubular spacer is inserted into the inner grooved tube in advance, and the inner grooved tube is expanded from the inner side with a tube expanding tool.
JP 2001-74384 A (paragraph 0011, FIG. 1) JP 2000-218332 A (paragraphs 0011 and 0012, FIGS. 1 to 3)

  However, although Patent Document 1 can prevent excessive fin deformation during tube expansion, there is still a problem that fin deformation still occurs. Moreover, in patent document 2, the operation | work which inserts and takes out a spacer inside an internally grooved pipe | tube is needed for every pipe expansion work, and there existed a problem that workability | operativity fell. As a result, it was not suitable for mass production work and was not practical.

  Therefore, the present invention has been made in view of such problems, and even if the groove shape of the inner surface grooved tube is changed to high lead, high fin, slim fin and the bottom wall thickness is increased, fin deformation due to expansion of the tube is suppressed. It is another object of the present invention to provide a tool for expanding an internally grooved tube and a method of expanding the pipe using the same, in which the heat transfer performance does not deteriorate and the workability of the pipe expanding operation does not deteriorate.

In order to solve the above-mentioned problem, the invention of claim 1 is inserted into an inner surface grooved tube used in a heat exchanger, moved in the axial direction of the inner surface grooved tube, and the inner surface grooved tube. Is a tube expansion tool for an inner surface grooved tube for a heat exchanger that expands the tube to a tube expansion ratio of 3% or more and 8% or less, and the inner surface grooved tube is formed on the inner surface in a direction inclined in the tube axis direction. A groove and a fin formed between the grooves, wherein the inner surface grooved tube has a tube outer diameter (D) of 4 mm to 10 mm, and the number of grooves is 30 to 100, The groove lead angle (θ) formed by the tube axis is 10 ° to 50 °, and the bottom wall thickness (t) of the internally grooved tube in the cross section perpendicular to the tube axis of the internally grooved tube is 0.2 mm to 1.0 mm. The fin height (h) of the fin is not less than 0.1 mm and not more than 1.2 times the bottom wall thickness. (Δ) is not less than 5 degrees and not more than 45 degrees, the fin base radius (r) is not less than 20% and not more than 50% of the fin height (h), and the cylindrical tube expansion is in contact with the inner surface of the inner grooved tube A burette and a mandrel connected to a rear end portion of the expanded burette. The expanded burette has a curved outer peripheral surface that contacts the inner surface of the inner grooved tube, and a radius (R ), The coefficient (α) calculated from α = R / (D / d) using the tube outer diameter (D) and the tube minimum inner diameter (d) of the inner grooved tube is 4.71 or more and 15 or less. It is configured as a tube expansion tool for an internally grooved tube for a heat exchanger.

If comprised in this way, by identifying the outer peripheral surface which contacts an inner surface grooved tube inner surface, in the expansion of an inner surface grooved tube, the frictional force between the expanded burette and the fin formed on the inner surface grooved tube inner surface is reduced. The inner surface grooved tube is expanded so that the fin deformation is suppressed and the fin plate of the heat exchanger is joined without a gap, and the inner surface grooved tube does not cause a defect such as a crack in the fin plate. Can be expanded. Thereby, when the refrigerant is supplied into the inner grooved tube, the diffusion of the refrigerant in the inner grooved tube is improved, and the heat exchange rate with the fin plate is also improved. Further, by specifying the groove shape formed on the inner surface grooved tube inner surface, the frictional force between the expanded burette and the fin in the expansion of the inner surface grooved tube is further reduced, and the fin deformation is further reduced. Further, when the refrigerant is supplied into the inner grooved tube, the diffusion of the refrigerant in the inner grooved tube is further improved.

Further, the invention of claim 2 is an internally grooved tube which is used in a heat exchanger using the tube expansion tool according to claim 1 and has a plurality of grooves and fins formed between the grooves on the inner surface thereof. In which the inner grooved tube is passed through a plate-like fin plate having a through hole of 102% or more and 105% or less of the outer diameter (D) of the inner grooved tube. A second step of inserting the tube expansion tool into the inner grooved tube penetrated through the step, and moving the inserted tube expansion tool in the tube axis direction of the inner grooved tube, A third step of expanding the tube, and a fourth step of taking out the inserted tube expansion tool from the inside of the inner grooved tube, and expanding the fin of the inner grooved tube expanded in the fourth step. The fin height is the fin height of the inner grooved tube in the first step. Those configured as pipe expansion method for down height heat exchanger inner surface grooved tube is 90% or more.

  If comprised in this way, in an expansion work of an inner surface grooved pipe, it is a simple mechanical pipe expansion method, without performing complicated work processes, such as insertion and extraction of a spacer etc. in an inner surface grooved pipe, and simple. Using the tube expansion tool with the structure, while suppressing the fin deformation of the fin formed in the inner surface grooved tube, it joins with the fin plate without gaps, and does not cause defects such as cracking of the fin plate. The grooved tube is expanded.

  According to the present invention as described above, even if the groove shape of the internally grooved tube is changed to high lead, high fin, slim fin and the bottom wall thickness is increased, fin deformation due to tube expansion is suppressed and heat transfer performance is achieved. It is possible to provide a tool for expanding a grooved tube with an inner surface and a method of expanding the pipe using the same.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. 1A is a perspective view showing the configuration of a tube expanding tool, FIG. 1B is a side view, FIG. 2 is a cross-sectional view schematically showing a method of expanding the inner grooved tube, and FIG. 3 is a configuration of the inner grooved tube. 4A is a sectional view taken along the line XX of FIG. 3, FIG. 4B is a partially enlarged view of FIG. 5A, and FIG. 5 is a plan view showing the configuration of the plate fins. 6 (a) is a partially broken front view of a heat exchanger incorporating an internally grooved tube, (b) is a view of the heat exchanger of (a) as viewed from the U-bend tube side, and (c) is (a). FIG. 7A is a schematic view of a suction type wind tunnel used when measuring the heat transfer performance of the heat exchanger, and FIG. 7B is a suction type of FIG. It is a schematic diagram of the refrigerant | coolant supply apparatus which supplies a refrigerant | coolant to a wind tunnel.

First, the tube expansion tool of the present invention will be described.
1. 2. Tube expansion tool As shown in FIG. 2, the tube expansion tool 20 is inserted into the inner surface grooved tube 1 used in the heat exchanger, moved in the tube axis direction of the inner surface grooved tube 1, and the inner surface thereof. The grooved tube 1 is expanded to a tube expansion rate of 3% or more and 8% or less. Here, the tube expansion rate (%) is [(the tube outer diameter D ′ of the inner grooved tube 1 after the tube expansion−the tube outer diameter D of the inner grooved tube 1 before the tube expansion) / the inner grooved tube 1 before the tube expansion]. The tube outer diameter D] × 100 is calculated, and if the tube expansion rate is less than 3%, the inner grooved tube 1 and the fin plate 11 are not joined without a gap, and if the tube expansion rate exceeds 8%, the fin plate 11 is cracked. In any case, the heat exchange rate between the internally grooved tube 1 and the fin plate 11 is deteriorated.

As shown in FIGS. 1 and 2, the tube expansion tool 20 includes a cylindrical tube expansion burette 22 that contacts the inner surface of the inner grooved tube 1, and a mandrel 21 connected to the rear end portion of the tube expansion burette 22. With.
(Expanded burette)
The expanded burette 22 is a cylindrical member and is made of cemented carbide, bearing steel, stainless steel, or the like. The size of the cylindrical member is as follows. When the diameter A1 is smaller than the minimum inner diameter d of the inner surface grooved tube 1 and the diameter A1 is equal to or larger than the minimum tube inner diameter d, the expanded burette 22 is moved into the inner surface grooved tube 1 when the inner surface grooved tube 1 is expanded. It becomes difficult to insert (see FIG. 4A). Further, the diameter A2 is appropriately set based on the expansion ratio of the inner grooved tube 1, the inner groove shape, and the degree of deformation of the fins 3. Moreover, the length L is 2 mm or more and 20 mm or less, and if the length L is less than 2 mm, the strength of the tube expansion burette 22 is insufficient, and if the length L exceeds 20 mm, a trouble of tube expansion work tends to occur. And it has the outer peripheral surface 22a on the curved surface which contacts the inner surface of the inner surface grooved pipe 1.

  The coefficient α calculated by α = R / (D / d) is 3 using the radius R of the outer peripheral surface 22a, the tube outer diameter D and the tube minimum inner diameter d of the inner grooved tube 1 in FIG. It is 15 or less. When the coefficient α is within the above range, the frictional force between the outer peripheral surface 22a and the fin 3 on the inner surface of the grooved tube 1 is reduced, and as will be described later, the fin deformation rate is 10% or less, and the fin 3 is deformed. It is suppressed.

  Here, when the coefficient α is less than 3, the pipe outer diameter D of the inner surface grooved tube 1 rapidly increases, and the frictional force between the outer peripheral surface 22a of the expanded burette 22 and the fin 3 on the inner surface of the inner surface grooved tube 1 is increased. The fin 3 is greatly deformed (see FIG. 8). When the coefficient α exceeds 15, the frictional force between the outer peripheral surface 22a of the expanded burette 22 and the fin 3 is hardly reduced, and the effect of suppressing the deformation of the fin 3 is not further improved. Furthermore, when expanding the inner grooved tube 1, it becomes difficult to insert the expanded burette 22 into the inner grooved tube 1 or the length L of the expanded burette 22 becomes too long. It can be a cause.

(Mandrel)
The mandrel 21 has a tip connected to the rear end of the expanded burette 22 and a terminal connected to a hydraulic device or a hydraulic device (not shown). And it is a guide at the time of inserting the pipe expansion burette 22 in the inner surface grooved pipe 1, and the pipe expansion burette 22 is moved in the tube axis direction in the inner surface grooved pipe 1 by driving of a hydraulic device or a hydraulic device. The mandrel 21 is a rod-shaped member having a diameter of 2 mm or more and 8 mm or less, and is made of cemented carbide, bearing steel, stainless steel, or the like.

  Moreover, it is preferable to use the tube expansion tool 20 in combination with the inner grooved tube 1 having the following inner groove shape.

(Inner grooved tube)
Since the inner grooved tube 1 is used for a plate fin tube type heat exchanger of an air conditioner and a refrigeration air conditioner, a tube outer diameter D of the tube is 4 mm or more and 10 mm or less. Moreover, as a material of the raw pipe of the inner surface grooved pipe 1, copper or a copper alloy is used, for example, phosphorus deoxidized copper such as alloy numbers C1220 and C1201 defined in JISH3300, or oxygen-free copper such as C1020. is there. In addition, although the formation method of the inner surface groove shape of the inner surface grooved pipe 1 includes a rolling method and a rolling method, it is not particularly limited.

  As shown in FIGS. 3 and 4, the inner surface grooved tube 1 includes a plurality of grooves 2 formed on the inner surface in a direction inclined in the tube axis direction, and fins 3 formed between the grooves 2. And the groove lead angle θ formed by the groove 2 and the tube axis is 10 degrees or more and 50 degrees or less, and the inner surface groove in the cross section perpendicular to the tube axis of the inner grooved tube 1. The bottom thickness T of the attached tube 1 is 0.2 mm or more and 1.0 mm or less, the fin height h of the fin is 0.1 mm or more and 1.2 times or less of the bottom thickness T, and the fin peak angle δ is 5 The fin base radius r is not less than 20% and not more than 50% of the fin height h.

Next, the numerical limitation in the inner surface groove shape of the inner surface grooved tube 1 will be described.
(1) Number of grooves: 30 or more and 100 or less The number of grooves is determined as appropriate in consideration of heat transfer performance, unit weight, etc. in combination with each specification of the inner surface groove shape described later. 100 or less is preferable. If the number of grooves is less than 30, the groove formability tends to deteriorate, and if the number of grooves exceeds 100, the grooved tool (grooved plug) tends to be damaged. In either case, the mass productivity of the internally grooved tube 1 is likely to decrease.

(2) Groove lead angle θ: 10 degrees to 50 degrees The groove lead angle θ is preferably 10 degrees to 50 degrees. When the groove lead angle θ is less than 10 degrees, the heat transfer performance of the internally grooved tube 1 (heat exchanger) tends to be lowered. Further, when the groove lead angle θ exceeds 50 degrees, it becomes difficult to ensure the mass productivity of the internally grooved tube 1 and to suppress the deformation of the fin 3 due to the tube expansion.
(3) Bottom thickness T: 0.2 mm or more and 1.0 mm or less Bottom thickness T is preferably 0.2 mm or more and 1.0 mm or less. When the bottom wall thickness T is out of the above range, it becomes difficult to manufacture the inner grooved tube 1. In addition, when the bottom wall thickness T is less than 0.2 mm, the strength of the inner grooved tube 1 is likely to decrease, and when using carbon dioxide gas or the like as a high-pressure refrigerant, it is difficult to maintain the pressure resistance strength.

(4) Fin height h: 0.1 mm or more (bottom thickness T × 1.2) mm or less The fin height h is preferably 0.1 mm or more (bottom thickness T × 1.2) mm or less. If the fin height h is less than 0.1 mm, the heat transfer performance of the internally grooved tube 1 (heat exchanger) tends to be lowered. Further, if the fin height h exceeds (bottom wall thickness T × 1.2) mm, it becomes difficult to ensure the mass productivity of the internally grooved tube 1 and to suppress the extreme deformation of the fin 3 due to the tube expansion.

(5) Summit angle δ: 5 degrees or more and 45 degrees or less The summit angle δ is preferably 5 degrees or more and 45 degrees or less. When the peak angle δ is less than 5 degrees, it becomes difficult to ensure the mass productivity of the internally grooved tube 1 and to suppress the deformation of the fin 3 due to the tube expansion. In addition, when the summit angle δ exceeds 45 degrees, the maintenance of the heat transfer performance of the internally grooved tube 1 (heat exchanger) and the single weight of the internally grooved tube 1 tend to be excessive.

(6) Fin root radius r: 20% to 50% of fin height h The fin root radius r is preferably 20% to 50% of the fin height h. When the fin root radius r is less than 20% of the fin height h, the fin inclination due to the tube expansion tends to be excessive, and the mass productivity tends to decrease. Moreover, if the fin root radius r exceeds 50% of the fin height h, the effective heat transfer area of the refrigerant gas-liquid interface tends to decrease, and the heat transfer performance of the inner grooved tube 1 (heat exchanger) tends to deteriorate. .

(Heat exchanger)
Next, the heat exchanger manufactured using the tube expansion tool of the present invention will be described. 5 and 6 are preferable examples of the plate fin tube type heat exchanger 10. As shown in FIGS. 5 and 6, the heat exchanger 10 is provided on a plurality of thin plate-like fin plates 11 arranged in parallel to each other at a predetermined interval (fin pitch Pb), and these fin plates 11. A plurality of internally grooved tubes 1 that are inserted into a plurality of through holes 11a and are processed to have a predetermined width (bending pitch Pa) in a U-shape joined so as to be orthogonal to the fin plate 11, and these internally grooved tubes 1 The inner grooved tube 1 is joined to the fin plate 11 in the longitudinal direction of the fin plate 11 at a predetermined interval (step direction pitch: the same interval as the bending pitch Pa), and at a predetermined interval (row pitch Pc). And a U vent pipe 12 connected in series in a plurality of rows.

  The fin plate 11 is made of aluminum (including an aluminum alloy) or copper (including a copper alloy), preferably 1000 series aluminum as defined in JISH4000, in consideration of heat transfer performance and weight reduction. A recess 11b is formed. The formation of the recess 11b increases the surface area of the fin plate 11 and improves the heat transfer performance. Further, the outer diameter of the plurality of through holes 11a provided in the fin plate 11 is 102% or more and 105% or less of the pipe outer diameter D of the inner grooved pipe 1 (see FIG. 4A). If the outer diameter of the through hole 11a is less than 102%, the expansion rate of the through hole 11a becomes excessive due to the expansion of the inner grooved tube 1, and problems such as cracks occur in the fin plate 11. On the other hand, if it exceeds 105%, the enlargement rate is insufficient. In either case, the degree of adhesion between the internally grooved tube 1 and the fin plate 11 rapidly decreases, and the heat transfer performance of the heat exchanger 10 decreases.

  Further, the U vent pipe 12 is made of aluminum (including an aluminum alloy) or copper (including a copper alloy), preferably 1000 series aluminum as defined in JISH4000, in consideration of heat transfer performance and weight reduction.

2. Tube expansion method Next, the tube expansion method of the present invention will be described by explaining a method for manufacturing a heat exchanger. As shown in FIG. 2, the following steps are included.
(First step)
A plurality of inner surface grooves processed in advance in a U-shape on a plurality of fin plates 11 arranged in parallel with each other and having through holes 11a of 102% to 105% of the outer diameter (D) of the inner surface grooved tube 1 The auxiliary tube 1 is penetrated. And as shown in FIG.6 (c), the inner surface grooved pipe | tube 1 is arrange | positioned to the longitudinal direction of the fin plate 11 in multiple steps and multiple rows.
(Second step)
The tube expansion tool 20 is inserted into the inner grooved tube 1 that penetrates the fin plate 11 and is arranged in a plurality of rows and rows. This operation is performed by driving a hydraulic device or a hydraulic device (not shown).
(Third step)
The inserted tube expansion tool 20 is moved in the tube axis direction of the internally grooved tube 1 to expand the internally grooved tube 1. By this operation, the inner grooved tube 1 is expanded to a tube expansion ratio of 3% or more and 8% or less, and the inner grooved tube 1 and the fin plate 11 are joined without a gap.
(4th process)
A hydraulic device or a hydraulic device (not shown) is driven to take out the inserted tube expansion tool 20 from the inside of the inner grooved tube 1 expanded. And the heat exchanger 10 is manufactured by joining the U vent pipe 12 to both ends of the inner surface grooved pipe 1 joined to the fin plate 11 and brazing as shown in FIG. The

  The tube expansion tool 20 in the second to fourth steps has the above-described configuration, that is, the radius (R) of the outer peripheral surface 22a of the tube expansion burette 22, the tube outer diameter D and the tube minimum inner diameter of the inner grooved tube 1. When the coefficient α calculated by α = R / (D / d) using d is not less than 3 and not more than 15 (see FIGS. 1 and 4), as shown in FIG. The pipe outer diameter D is gradually increased, the frictional force between the outer peripheral surface 22a of the pipe expansion burette 22 and the fin 3 of the inner grooved pipe 1 is reduced, and the deformation of the fin 3 is suppressed. As a result, the fin height of the inner grooved tube 1 expanded in the fourth step is 90% or more of the fin height of the inner grooved tube 1 in the first step (fin reduction rate of 10% or less).

  If the fin height in the fourth step is less than 90% of the fin height in the first step, the fins 3 are significantly deformed, and the diffusion of the refrigerant supplied to the inner grooved tube 1 is significantly hindered. Thus, the heat transfer performance of the internally grooved tube 1 (heat exchanger 10) is significantly reduced.

Next, examples in which the effects of the present invention have been confirmed will be described.
(First embodiment)
The expansion burette having the configuration shown in FIG. 1 was made of cemented carbide, and the expansion burette satisfying the claims of the present invention was designated as Examples 1-2. Further, it does not satisfy the claims of the present invention, that is, the radius R of the outer peripheral surface 22a of the tube expansion burette 22 is small, the tube outer diameter D and the tube minimum inner diameter d of the inner grooved tube 1 (FIG. 1, FIG. The expansion burette in which the coefficient α calculated in (1) is less than the lower limit value of the claims is defined as Comparative Example 1. Table 2 shows the shape dimensions of each burette for tube expansion.

  Further, an internally grooved tube 1 having a groove shape (No. A) shown in Table 1 was produced. The inner grooved tube 1 is manufactured by first melting phosphor deoxidized copper of alloy number C1220 specified in JISH3300, casting, hot extrusion, cold rolling, and cold drawing, and performing a cold drawing process. Was made. Next, a first diameter reduction process is performed on the element pipe, a second diameter reduction process is performed while forming the inner surface groove-shaped spiral groove on the diameter-reduced element pipe, and the element in which the spiral groove is formed. The tube was subjected to third diameter reduction processing to produce an internally grooved tube 1 having a tube outer diameter D of 7 mm.

Next, the inner grooved tube 1 was expanded with each expansion burette, and the plate fin tube type heat exchanger 10 shown in FIGS. 5 and 6 was produced. The specifications of the heat exchanger 10 were as follows.
(Heat exchanger 10)
The outer shape was 250 mm high × 250 mm long × 25.4 mm wide.
(Fin plate 11)
A plate material made of aluminum having an alloy number of 1N30 specified in JISH4000, and the surface of the plate material is coated with a resin. Further, the thickness of the fin plate 11 was 100 μm, and the diameter of the through hole 11a was 7.3 mm. Then, 200 fin plates 11 were arranged in parallel at a fin pitch Pb of 1.25 mm.
(Arrangement of inner grooved tube 1)
The inner grooved tube 1 is processed into a U shape, inserted into a through hole 11a provided in the fin plate 11, and arranged in two rows and 12 steps (bending pitch Pa21mm, row direction pitch Pc12.7mm) (effective heat transfer tube) The length was about 6.7 m).

  Next, the fin reduction rate of the inner surface grooved tube 1 was measured using the inner surface grooved tube 1 of the heat exchanger 10. Here, the fin reduction rate (%) is calculated by [((fin height after pipe expansion) − (fin height before pipe expansion)) / (fin height before pipe expansion)] × 100, and the result is shown in Table 1. It was shown in 2. When the fin reduction rate was 10% or less, the fin height after tube expansion was 90% or more of the fin height before tube expansion, and it was determined that no fin deformation occurred.

  And heat transfer performance (evaporation performance, condensation performance) was measured using this heat exchanger 10, and the result was shown in Table 2. Here, the evaporating performance and the condensing performance are described as ratios when the overall heat transfer coefficient is measured and the comparative example 1 is set to “100”.

  Moreover, the schematic diagram of the measuring apparatus which measures heat-transfer performance to Fig.7 (a), (b) is shown. As shown to Fig.7 (a), a measuring apparatus consists of the suction type wind tunnel 100 with a constant temperature and humidity function, the refrigerant | coolant supply apparatus 110 (refer FIG.7 (b)), and an air conditioner (not shown). In the suction type wind tunnel 100, the heat exchanger 10 is arranged in the flow path of the air that flows in from the air inlet 108 and is discharged from the air outlet 109, and upstream and downstream of the heat exchanger 10, respectively. Air samplers 101 and 102 are arranged. The air samplers 101 and 102 are connected to temperature and humidity measuring boxes 103 and 104, respectively. The temperature and humidity measuring boxes 103 and 104 measure the temperature and humidity of the air by measuring the dry bulb temperature and the wet bulb temperature of the air collected by the air samplers 101 and 102, respectively. An induction fan 105 is provided on the downstream side of the air sampler 102 and discharges air to the air discharge port 109. Rectifiers 106 and 106 for rectifying the air that has passed through the heat exchanger 10 are provided between the heat exchanger 10 and the air sampler 102 and between the air sampler 102 and the induction fan 105.

  Moreover, the schematic diagram of the refrigerant | coolant supply apparatus 110 is shown in FIG.7 (b). In FIG. 7B, 107 is a refrigerant pipe, 111 is a sight glass, 112 is a heat exchanger for liquid (refrigerant) heating and cooling, 113 is a dryer, 114 is a liquid receiver (refrigerant), 115 is a fusing plug, 116 Is a condenser, 117 is an oil separator, 118 is a compressor, 119 is an accumulator, 120 is an evaporator, 121 is an expansion valve, and 122 is a flow meter. And the refrigerant | coolant which adjusted the pressure and temperature is supplied through the refrigerant | coolant piping 107 into the inside grooved pipe 1 (refer FIG. 6) of the heat exchanger 10 with which the suction type wind tunnel 100 was equipped. In addition, a pressure gauge 123 (the temperature is a saturation temperature corresponding to the measured pressure) is provided at the inlet and outlet of the heat exchanger 10 to measure the temperature and pressure of the refrigerant. Further, the air conditioner (not shown) supplies air with controlled temperature and humidity to the air inlet 108 of the suction type wind tunnel 100.

  The measurement conditions were as shown in Table 3, R410A was used as the refrigerant, and the refrigerant flow rate was 30 kg / h. In addition, the flow of the refrigerant at the time of measuring the evaporation performance and the flow of the refrigerant at the time of measuring the condensation performance are different from each other (the flow direction of the refrigerant in the refrigerant supply device 110 shown in FIG. 7B is evaporation). Shows the flow direction of the refrigerant during the performance measurement).

  From the results in Table 2, it was confirmed that Examples 1-2 of the present invention were superior in fin reduction rate and heat transfer performance (evaporation performance and condensation performance) as compared with Comparative Example 1.

(Second embodiment)
Similarly to the first example, the expansion burette satisfying the claims of the present invention was designated as Examples 3 to 4, and the expansion burette satisfying the claims of the present invention was designated as Comparative Example 2. Table 4 shows the shape dimensions of each burette for tube expansion. Further, in the same manner as in the first example, an internally grooved tube 1 having a groove shape (No. B) shown in Table 1 was produced.

  Next, the heat exchanger 10 was produced in the same manner as in the first example, and the fin reduction rate of the inner grooved tube 1 was measured. Further, the heat transfer performance (evaporation performance, condensation performance) was measured with the suction type wind tunnel 100 (refrigerant supply device 110) using the heat exchanger 10. The results are shown in Table 4. Here, the evaporating performance and the condensing performance are described as ratios when the overall heat transfer coefficient is measured and the comparative example 2 is set to “100”.

表４の結果より、本発明の実施例３〜４は、比較例２に比べて、フィン減少率および伝熱性能（蒸発性能および凝縮性能）が優れていることが確認された。

From the results of Table 4, it was confirmed that Examples 3 to 4 of the present invention were superior in fin reduction rate and heat transfer performance (evaporation performance and condensation performance) as compared with Comparative Example 2.

(A) is a perspective view which shows the structure of the tool for pipe expansion concerning this invention, (b) is a side view. It is sectional drawing which shows typically the pipe expansion method of the internal grooved pipe which concerns on this invention. It is sectional drawing of the pipe-axis direction which shows the structure of an internal grooved pipe | tube. (A) is the XX sectional drawing of FIG. 3, (b) is the elements on larger scale of (a). It is a top view which shows the structure of a plate fin. (A) is a partially broken front view of a heat exchanger incorporating an internally grooved tube, (b) is a view of the heat exchanger of (a) seen from the U-bend tube side, and (c) is of (a). It is the figure which looked at the heat exchanger from the hairpin tube side. (A) is a schematic diagram of the suction type wind tunnel used when measuring the heat transfer performance of the heat exchanger, and (b) is a schematic diagram of a refrigerant supply device for supplying a refrigerant to the suction type wind tunnel of (a). It is sectional drawing which shows typically the pipe expansion method of the conventional internal grooved pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal grooved tube 10 Heat exchanger 20 Tube expansion tool 21 Mandrel 22 Tube expansion bullet 22a Outer peripheral surface R Radius D Tube outer diameter d Tube minimum inner diameter

Claims (2)

Heat exchange that is inserted into the inner grooved tube used in the heat exchanger and moves in the axial direction of the inner grooved tube to expand the inner grooved tube to a tube expansion rate of 3% to 8%. A tool for expanding a grooved pipe for internal use,
The inner surface grooved tube has a structure having a large number of grooves formed on the inner surface in a direction inclined in the tube axis direction, and fins formed between the grooves, and the tube outer diameter of the inner surface grooved tube (D) is 4 mm or more and 10 mm or less, the number of grooves of the groove is 30 or more and 100 or less, the groove lead angle (θ) formed by the groove and the tube axis is 10 degrees or more and 50 degrees or less, and the tube axis of the inner grooved tube The bottom wall thickness (T) of the internally grooved tube in the orthogonal cross section is 0.2 mm or more and 1.0 mm or less, and the fin height (h) of the fin is 0.1 mm or more and 1.2 times the bottom wall thickness. Hereinafter, the fin peak angle (δ) is not less than 5 degrees and not more than 45 degrees, the fin root radius (r) is not less than 20% and not more than 50% of the fin height (h),
A cylindrical tube expansion burette that contacts the inner surface of the inner grooved tube, and a mandrel connected to the rear end of the tube expansion burette,
The expanded burette has a curved outer peripheral surface that comes into contact with the inner surface of the inner grooved tube, the radius (R) of the outer peripheral surface, the outer diameter (D) of the inner grooved tube, and the minimum inner diameter of the tube ( A tube expansion tool for an internally grooved tube for a heat exchanger, wherein the coefficient (α) calculated by α = R / (D / d) using d) is 4.71 or more and 15 or less. A tube expansion method using the tube expansion tool according to claim 1 for expanding an internally grooved tube having a plurality of grooves and fins formed between the grooves used on a heat exchanger. ,
A first step of allowing the inner grooved tube to pass through a plate-like fin plate having a through hole of 102% or more and 105% or less of the outer diameter (D) of the inner grooved tube;
A second step of inserting the tube expansion tool into the inner grooved tube penetrated;
A third step of expanding the inner grooved tube by moving the inserted tube expanding tool in the tube axis direction of the inner grooved tube;
A fourth step of taking out the inserted tool for expanding the tube from the inside of the inner grooved tube expanded,
The fin height of the fin of the inner grooved tube expanded in the fourth step is 90% or more of the fin height of the fin of the inner grooved tube in the first step. Method of expanding inner grooved tube.

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