WO2017026510A1 - Aluminum extruded flat perforated pipe having excellent internal surface anticorrosion property and aluminum heat exchanger using same - Google Patents

Abstract

In this aluminum extruded flat perforated pipe, the anticorrosion property, at internal surfaces of a plurality of pores independently and parallelly extending in the pipe axis direction, is effectively enhanced. In an aluminum extruded flat perforated pipe 10 formed through an extrusion process by using an aluminum pipe body material and an aluminum sacrificial anode material which is electrochemically less noble than the aluminum pipe body material, a sacrificial anode part 18 is formed by causing the aluminum sacrificial anode material to be exposed at least in one portion of a hole-internal circumference section of each of the plurality of pores 12 extending in the pipe axis direction.

Description

Aluminum extruded flat multi-hole tube with excellent inner surface anticorrosion property and aluminum heat exchanger using the same

The present invention relates to an aluminum extruded flat multi-hole tube having excellent inner surface anticorrosion properties and an aluminum heat exchanger using the same, and in particular, transmission of heat exchangers, particularly automobile heat exchangers such as car air conditioners and radiators. It relates to an aluminum extruded flat multi-hole tube for heat exchangers that can be suitably used as a heat tube and has excellent corrosion resistance on the inner surface of the flow path through which coolant flows, and an aluminum heat exchanger obtained by using the same. is there.

Conventionally, in heat exchangers such as radiators and heaters where the heat transfer tube serves as a flow path for the cooling liquid, a plate material in which a sacrificial material is clad on the surface on the tube inner surface side to prevent the inner surface of the heat transfer tube. A plate-shaped heat transfer tube formed by bending the tube into a tube shape has been used. In particular, increasing the number of flow paths is effective for improving the performance of heat exchangers. In plate heat transfer tubes, by providing inner fins, multiple flow paths can be placed in the tubes. It is formed. However, since such a structure has many joint points, there is a problem that a brazed joint failure is likely to occur, and there is a concern that burst due to insufficient pressure strength. Further, problems such as clogging of the flow path formed on the inner surface are inherent due to the flux used during brazing. In order to solve these problems, it is effective to use an extruded flat multi-hole tube that is manufactured without using the flux as the partition wall of each flow path is not brazed.

As such an extruded flat multi-hole tube, one obtained by extrusion of aluminum or an aluminum alloy is usually used. For example, JP-A-6-142755 (Patent Document 1) and JP-A-5 A flat multi-hole tube having a cross-sectional shape as disclosed in JP-A-222480 (Patent Document 2), WO2013 / 125625 (Patent Document 3) and the like has been clarified.

By the way, in a flat multi-hole tube obtained by extrusion, which is used as a heat transfer tube of such a heat exchanger, as described above, the coolant flows through the flow path (passage) on the inner surface side. Therefore, there is a problem that corrosion is caused on the inner surface of the flow path due to such a cooling liquid, and the tube wall (outer peripheral wall) is caused by the progress of such corrosion. If a corrosive hole or the like is generated, the function as a heat exchanger is completely lost.

Therefore, in the above-described extruded flat multi-hole tube, as clearly disclosed in the above-mentioned JP-A-5-222480 (Patent Document 2), an aluminum alloy having a specific component composition is used singly, Although it has been proposed to produce a flat multi-hole tube having an appropriate anticorrosion property by extrusion, the anticorrosion property of the inner surface of the flow path is not sufficient, and in recent years there has been a demand for a high anticorrosion property. In addition to not being able to respond sufficiently, there is also a problem that the characteristics of the obtained tube are limited by the aluminum alloy of the specific alloy composition because the entire tube is made of an aluminum alloy of the specific material. ing.

JP-A-6-142755 JP-A-5-222480 WO2013 / 125625

Under such circumstances, the present inventors, in an aluminum extruded flat multi-hole tube obtained by extrusion processing of an aluminum material, have inner surface anticorrosive properties of a plurality of channels provided so as to extend independently from each other in the tube axis direction. As a result of diligent investigation to improve the performance, hot extrusion is performed using a normal aluminum tube body material and an aluminum sacrificial anode material that is more electrochemically base as the aluminum material to be extruded. Thus, the sacrificial anode part made of such an aluminum sacrificial anode material can be advantageously exposed on the inner surfaces of the plurality of flow paths of the obtained aluminum extruded flat multi-hole tube, and the sacrifice exhibited by the presence of the sacrificial anode part Due to the anode effect, it is possible to give excellent inner surface corrosion resistance to the flow path of such an aluminum extruded flat multi-hole tube. It was put out.

Therefore, the present invention has been completed based on such knowledge, and the problem to be solved is an aluminum extruded flat having an overall flat cross-sectional shape obtained by extrusion processing of an aluminum material. In the hole tube, it is to effectively enhance the corrosion resistance of the inner surface of the flow path provided so as to extend independently and parallel to each other in the tube axis direction, and another problem is that An object of the present invention is to provide an aluminum extruded flat multi-hole tube whose corrosion resistance is significantly enhanced by the sacrificial anode effect, and an aluminum heat exchanger excellent in corrosion resistance obtained by using the same.

In order to solve such problems, the present invention is an extruded tube having an overall flat cross-sectional shape obtained by extrusion of an aluminum material, and is independent of each other in the tube axis direction. A plurality of flow channels extending in parallel with each other, and the flow channels are formed into an aluminum extruded flat multi-hole tube arranged in the longitudinal direction of a flat shape via an internal partition wall portion extending in the tube axis direction, The aluminum material is formed by an extrusion process using an aluminum tube main body material and an aluminum sacrificial anode material that is electrochemically less basic than the aluminum tube main body material, and in each cross section of the plurality of flow paths. The sacrificial anode part is formed by exposing the aluminum sacrificial anode material in at least a part of the inner periphery of the flow path. Excellent aluminum extruded flat multi-hole tubes on the surface corrosion resistance, it is an gist thereof.

In the present invention, it is advantageous that the sacrificial anode portion is present at a ratio of 100% or less of the thickness of the internal partition wall portion in the internal partition wall portion positioned between adjacent ones of the plurality of flow paths. The sacrificial anode portion is present at a ratio of 90% or less of the thickness of the tube peripheral wall portion in the tube peripheral wall portion other than the internal partition wall portion.

Further, in one of desirable aspects of the aluminum extruded flat multi-hole tube according to the present invention, the aluminum sacrificial anode material is electrochemically lower than the aluminum tube body material, and the potential difference is 5 mV. As mentioned above, it is preferable that it is 300 mV or less.

Furthermore, in the present invention, the sacrificial anode portion described above is formed over a length of at least 10% of the circumferential length of the flow path in the tube cross section, and is exposed to the inner surface of the flow path. It is desirable.

In addition, according to one of the desirable embodiments of the present invention, among the internal partition walls existing between adjacent ones of the plurality of flow paths, the internal partition walls located at both ends in the longitudinal direction of the flat shape are , Each of which is thicker than the other internal partition walls.

Moreover, according to one of the further desirable other embodiments of the aluminum extruded flat multi-hole tube according to the present invention, the internal partition wall portion located between the adjacent ones of the plurality of flow paths is from a portion having the thinnest wall thickness. Extending in a wall thickness that increases continuously or stepwise toward the pipe peripheral wall portions on both sides connected by the internal partition wall portion, and the thinnest wall thickness of the internal partition wall portion with respect to the pipe peripheral wall portions on both sides They are connected by connecting portions having a thickness larger than the thickness of the part.

And in this invention, it is comprised including the aluminum extrusion flat multi-hole pipe | tube according to this invention as mentioned above, and the aluminum outer fin brazed and joined to the outer surface of this aluminum extrusion flat multi-hole pipe | tube. The gist of the present invention is also an aluminum heat exchanger.

Thus, in the aluminum extruded flat multi-hole tube configured according to the present invention, a sacrificial anode portion made of an aluminum sacrificial anode material is provided on the inner surfaces of a plurality of flow paths extending in parallel with each other in the tube axis direction. Since the exposed and existed portion, the sacrificial anode effect can effectively enhance the inner surface anticorrosion, and the inner surface of the tube, such as a radiator or heater, becomes a flow path for the cooling liquid. It could be advantageously used as a heat transfer tube for a heat exchanger.

In addition, the aluminum extruded flat multi-hole tube according to the present invention is composed of an aluminum tube main body material and an aluminum sacrificial anode material, and is formed by co-extrusion of these two materials. The inner surface corrosion resistance can be effectively exhibited by the aluminum sacrificial anode material while ensuring the aluminum tube main body material. This allows the design flexibility of the target extruded flat multi-hole tube. It also has the advantage that it can be advantageously increased.

Furthermore, in an aluminum heat exchanger constituted by assembling an aluminum extruded flat multi-hole tube according to the present invention and an aluminum outer fin and joining them by brazing heating, the aluminum extruded flat multi-hole The excellent internal anticorrosion properties of the tube can also advantageously increase the anticorrosion properties as a heat exchanger.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional explanatory drawing which shows typically an example of the aluminum extrusion flat multi-hole pipe | tube according to this invention, Comprising: (a) shows the whole figure, (b) shows the part expanded, (c) ) Is an explanatory view showing, in an enlarged manner, a part of an example in which the sacrificial anode part has different exposure ratios. It is a section partial explanatory view showing typically another example of each different example of an aluminum extrusion flat multi-hole tube according to the present invention, (a) shows a different example corresponding to FIG. 1 (c), (b) FIG. 2 conceptually shows a different example corresponding to FIG. It is sectional explanatory drawing which shows typically the various forms of the internal partition part in the aluminum extrusion flat multi-hole pipe according to this invention, Comprising: (a), (b) and (c) are examples from which an internal partition part differs, respectively. It is explanatory drawing shown. It is sectional explanatory drawing which shows typically another form of the internal partition part in the aluminum extrusion flat multi-hole pipe | tube according to this invention. It is explanatory drawing which shows the cross section of the composite billet used in the Example. It is explanatory drawing which shows the cross section of the single billet used in the comparative example.

Hereinafter, in order to clarify the present invention more specifically, representative embodiments of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 schematically shows an example of an aluminum extruded flat multi-hole pipe according to the present invention in the form of a cross section that is a cross section perpendicular to the longitudinal direction (tube axis direction). Yes. The flat multi-hole tube 10 according to the present invention is an extruded tube made of an aluminum material having a flat cross-sectional shape as a whole, and is composed of rectangular holes extending in parallel to the tube axis direction independently of each other. A plurality of passages 12 are provided, and the plurality of flow passages 12 are arranged in a flat longitudinal direction (left and right in the drawing) at a predetermined interval. The opposed upper and lower surfaces of the flat multi-hole tube 10 are flat surfaces, and there are outer fins such as known plate fins and corrugated fins made of aluminum or an alloy thereof as in the prior art (see FIG. (Not shown) can be attached by a joining method such as brazing and used as a heat exchanger. In addition, the cross-sectional shape of the flow path 12 is a rectangular shape here, but a known circular shape, an elliptical shape, a triangular shape, a trapezoidal shape, or a combination of various shapes may be employed. Is possible.

In the present invention, in the flat multi-hole tube 10 having such a structure, as apparent from FIG. 1A, at least the outer peripheral portion of the tube peripheral wall portion 14 is made of a normal aluminum tube main body material. On the other hand, a sacrificial anode portion 18 made of an aluminum sacrificial anode material is present around the flow channel 12 including the internal partition wall portion 16 located between the adjacent flow channels 12 and 12, The sacrificial anode portion 18 is exposed in at least a part of the inner peripheral portion of the flow path 12 (here, in the entire periphery). Here, as shown in the drawing, the tube peripheral wall portion 14 constitutes the outer peripheral wall of the flat multi-hole tube 10 and functions as an external partition wall for each flow path 12. Further, as shown in FIG. 1B, such a sacrificial anode portion 18 exists at a ratio of 100% or less of the thickness Tw of the internal partition wall portion 16 when it is located on the internal partition wall portion 16. The lower limit of the thickness is preferably at least 1% or more, more preferably 5% or more, of the thickness Tw of the internal partition wall 16. In this way, by forming the inner partition wall portion 16 with the sacrificial anode portion 18, the internal partition wall portion 16 is preferentially corroded by the sacrificial anode effect, and thus is caused by the corrosion of the pipe peripheral wall portion 14. The effect of suppressing or preventing penetration that causes coolant leakage at an early stage is advantageously exhibited.

On the other hand, when the sacrificial anode portion 18 is located on the tube peripheral wall portion 14 other than the internal partition wall portion 16, the thickness Ta is 90% or less of the thickness Ts of the tube peripheral wall portion 14, preferably 80%. It is made to exist in the following proportions, and the lower limit thereof is preferably 1% or more, more preferably 5% or more. That is, Ta ≦ 0.9 × Ts, and Ta ≧ 0.01 × Ts is preferable. If the sacrificial anode portion 18 exceeds 90% of the wall thickness Ts of the tube peripheral wall portion 14, the thickness of the tube peripheral wall portion 14 becomes too thin after the sacrificial consumption of the sacrificial anode portion 18, and the flat multi-hole tube 10 causes problems such as a decrease in pressure resistance.

In addition, the sacrificial anode portion 18 as described above is exposed on all inner surfaces of the plurality of flow paths 12 provided in the flat multi-hole tube 10, and such sacrificial anode portion 18 is It is desirable that the inner surface of the flow path 12 is continuously exposed in the tube axis direction, but it is also partially discontinuous, or at a plurality of positions in the tube circumferential direction within a predetermined length. Even if it is exposed in a form extending in the tube axis direction, there is no problem. In the present invention, a structure in which such a sacrificial anode portion 18 is always exposed to the inner surface of the flow path 12 in any cross section of the flat multi-hole tube 10 is advantageously employed. It will be.

Furthermore, the exposed area on the inner surface of the flow path 12 of the sacrificial anode portion 18 is exposed in a range corresponding to at least 10% or more of the circumferential length L in the cross section of the flow path 12 shown in FIG. It is desirable to be configured, and preferably 30% or more, more preferably 50% or more is advantageously employed. As described above, the sacrificial anode portion 18 is exposed over a longer region of the circumferential length L of the flow path 12, so that the corrosion resistance due to the sacrificial anode effect can be expressed more advantageously. In particular, the most preferable state is when the sacrificial anode portion 18 exists over the entire length L of the flow path 12 as shown in FIGS. In addition, it is not necessary to make all the exposed areas of the sacrificial anode part 18 in each flow path 12 the same. For example, as shown in FIG. It is also possible to expose 18.

It should be noted that the aluminum sacrificial anode material used in the present invention is electrochemically less basic than the aluminum tube body material. Therefore, the potential difference between these materials exceeds 0 mV, but is preferably in the range of 5 mV to 300 mV. When this potential difference is 5 mV or more, the sacrificial anode effect is surely easily exhibited even in a more severe corrosive environment. On the other hand, when the potential difference exceeds 300 mV, the sacrificial anode effect becomes prominent, and problems such as severe corrosion consumption of the sacrificial anode material are caused. As described above, the sacrificial anode portion 18 is lower in potential than the tube peripheral wall portion 14 or the like made of an aluminum tube main body material, so that an effective sacrificial anode effect can be exhibited, and the corrosion resistance of the inner surface of the flow path is It can be expressed more advantageously.

By the way, in such a flat multi-hole tube 10, as a tube body material constituting at least the outer peripheral portion of the tube peripheral wall portion 16, an aluminum material conventionally used for manufacturing a flat multi-hole tube by extrusion is used as it is. For example, JIS name A1000 series pure aluminum material, A3000 series aluminum alloy material, etc. can be used, and in order to make the electric potential noble in such an aluminum material, an alloy can be used. A predetermined amount of Cu may be contained as a component. As the sacrificial anode material for providing the sacrificial anode portion 18, a known aluminum alloy material that is electrochemically lower than the above-described tube body material, in other words, has a lower natural potential, is used. An aluminum alloy or the like including a fixed amount is used.

The flat multi-hole tube 10 according to the present invention as described above is manufactured by simultaneously extruding the above-described tube body material and sacrificial anode material as the extruded aluminum material. However, the tube body material and the sacrificial anode material are generally used as a composite billet having a core-sheath structure. Specifically, in the hollow portion provided in the tube body material (center portion), for example, a rectangular shape (including a curved corner portion), a circle, an oval, an ellipse, an oval and an oval A sacrificial anode material having a cross-sectional shape corresponding to the hollow portion, such as a combination of polygons and the like, and a sacrificial anode material having an optimized cross-sectional dimension is arranged and joined by welding or the like to be integrated. A composite billet having a structure in which a sheath portion made of a tube body material is formed around a core portion made of an anode material is used. The composite billet can be manufactured by using various known means, for example, forming a sheath billet by providing a through-hole of a predetermined size at the center of the billet made of the tube body material, and passing through the through-hole. In addition to a method in which a core billet made of a sacrificial anode material is inserted into the hole and integrated, such a sheath billet is produced in the form of two parts, and the core billet is placed in the space of the two parts of the sheath billet. In the arranged form, it is possible to form a target composite billet by a method of fixing the whole by welding or the like and integrating them.

Furthermore, a hot extruding technique is applied to such a composite billet using a die having a plurality of extrusion ports, a so-called port hole die, as in the case of manufacturing a conventional extruded flat multi-hole tube. Thus, the target extruded flat multi-hole tube can be obtained. At that time, a die having a long extrusion port arranged to correspond to a plurality of flow paths of the flat multi-hole tube On the other hand, the composite billet is arranged so that the longitudinal direction in the predetermined cross-sectional shape of the sacrificial anode material arranged inside the composite billet coincides with the longitudinal direction of the extrusion port of the die, Extrusion is performed. By adopting the extrusion form for the port hole die of such a composite billet, the sacrificial anode material in the composite billet is effectively applied to the partition wall partitioning the flow path located at both ends of the flat shape of the obtained flat multi-hole tube. The sacrificial anode part can be advantageously exposed to the inner peripheral surface of the flow path.

As described above, an aluminum extruded flat multi-hole tube according to the present invention manufactured by co-extrusion of an aluminum tube body material and an aluminum sacrificial anode material is generally shown in FIG. As shown in c), the ratio (area) of the sacrificial anode portion 18 exposed on the inner surface of the flow path varies depending on the position where the flow path 12 exists, and thereby the sacrificial anode portion in the internal partition wall portion 16 is formed. A difference in the 18 corrosion is likely to occur. That is, in the flow path 12a at the both ends in the width direction of the flat multi-hole tube 10 which are both ends of the flat shape in the longitudinal direction, it is more than the other flow paths 12b at the center portion side in the longitudinal direction of the flat shape. Also, the sacrificial anode portion 18 has a small exposure ratio (area), so that the space between the internal partition wall portion 16a partitioning the flow channel 12a and the internal partition wall portion 16b on the flat longitudinal central portion side of the flow channel 12b is reduced. A difference occurs in the corrosion of the sacrificial anode portion 18. Therefore, in the present invention, as shown in FIG. 2 (a), the thickness of the internal partition wall portion 16a that is positioned at both ends in the width direction of the flat multi-hole tube 10 and divides the flow path 12a at both ends. The thickness Twe is configured to be thicker than the thickness Twi of the other inner partition wall portion 16b positioned on the widthwise center portion side, so that the remaining thickness of the inner partition wall portion 16a on both end portions due to corrosion is reduced. It is recommended to improve.

Further, as shown in FIG. 1C and FIG. 2A, the sacrificial anode portion 18 is present in the inner partition wall portion 16 (16a, 16b) and is hardly present or present in the tube peripheral wall portion 14. Even if the thickness is smaller than the thickness of the internal partition wall portion 16, the internal partition wall portion 16 is mainly corroded. In the connection part 16c, it becomes easy to corrode preferentially. For this reason, in the present invention, as shown in FIG. 2B, the width Tb of the connecting portion 16c with respect to the pipe peripheral wall portion 14 of the internal partition wall portion 16 is set to the minimum thickness (wall) of the internal partition wall portion 16. The structure in which the thickness of the thinnest part) is larger than Tmin is advantageously employed, whereby the reduction in corrosion of the connecting portion 16c of the internal partition wall portion 16 can be advantageously improved. That is, the inner partition wall 16 positioned between adjacent ones of the plurality of flow paths is connected to the inner wall partition 16 from the thinnest portion of the wall thickness (up and down in FIG. 2B). The thickness Tmin of the thinnest wall thickness portion of the inner partition wall portion 16 is extended with respect to the tube peripheral wall portion 14, which is continuously or stepwisely increased. It is desirable that the connecting portions 16c and 16c having a greater thickness (width) be connected to each other. Here, the width Tb of the connecting portion 16c means the distance between the portions that rise from the tube peripheral wall portion 14 on both sides of the internal partition wall portion 16 and provide the inner peripheral wall portion 16 (connecting portion 16c). .

And the form of the preferable connection part 16c of this invention is not limited to the shape shown by FIG.2 (b), For example, it is also possible to employ | adopt a shape as shown, for example in FIG.3 and FIG.4. is there. Specifically, in FIG. 3A, a shape in which the thickness of the internal partition wall portion 16 changes linearly from the minimum thickness portion of the internal partition wall portion 16 is adopted, and FIG. FIG. 3C shows a form in which the thickness is curvedly thicker than the thickness Tmin of the minimum thickness portion of the internal partition wall portion 16, and in FIG. 3C, the upper pipe peripheral wall portion 14 in FIG. The minimum thickness portion of the internal partition wall portion 16 is located at a close position, and from there, the wall thickness is increased linearly or curvedly toward the pipe peripheral wall portion 14 located on both sides in the vertical direction. Thus, the upper and lower pipe peripheral wall portions 14 and 14 are connected to each other. In addition, in the form shown in FIG. 3C, the upper and lower connecting portions 16c, 16c of the internal partition wall portion 16 have different widths (T′b <Tb). Furthermore, in FIG. 4, the minimum thickness portion of the internal partition wall portion 16 is present over a predetermined length in the vertical direction, and the wall thickness is gradually increased (in the stepped structure in the stepped structure). ) Increased and connected to the upper and lower pipe peripheral wall portions 14, 14, respectively. In addition, although the shape of both sides of the example internal partition part 16 is made into the same shape, of course, it can also be set as a different shape. As described above, it is understood that the shape of the internal partition wall portion 16 connected to the pipe peripheral wall portion 14 via the connection portion 16c according to the present invention can be variously changed based on the knowledge of those skilled in the art. It should be.

Incidentally, the aluminum extruded flat multi-hole tube according to the present invention as described above can be suitably used as a refrigerant flow path member in a heat exchanger. And when using the aluminum extrusion flat multi-hole pipe according to the present invention as a refrigerant passage pipe, for example, a pair of aluminum header tanks arranged at a distance from each other, and a width direction ventilation direction between both header tanks Facing each other, a plurality of extruded aluminum flat multi-hole pipes arranged in parallel with each other at intervals in the longitudinal direction of the header tank and having both ends connected to both header tanks, and adjacent flat multi-hole pipes Between and between the flat multi-hole pipes at both ends and brazed to these flat multi-hole pipes, and aluminum corrugated fins as outer fins, and arranged outside the corrugated fins at both ends, In a structure comprising an aluminum side plate brazed to such fins, a heat exchanger will be configured. Of course, in addition to the heat exchanger of such structures, as the refrigerant tube in the heat exchanger of various known, that can be used aluminum extruded flat multi-hole tube according to the present invention, it is needless to say place.

As is well known, a pair of header tanks in a heat exchanger distributes and flows refrigerant or coolant from one header tank to a flat multi-hole tube, and the other header tank is flat flat. For collecting refrigerant or coolant flowing out of the hole tube, for example, as is known, the header plate and the header plate are brazed oppositely, or the plate is bent into an annular shape, and the end portion In addition to those constructed by welding or brazing, an extruded tube or the like extruded in an annular shape is used.

The exemplary embodiments of the present invention have been described in detail above, but these are merely examples, and the present invention is interpreted in a limited manner by specific descriptions according to such embodiments. It should be understood that it is not done.

And this invention can be implemented in the aspect which added various change, correction, improvement, etc. based on the knowledge of those skilled in the art, and such an aspect does not deviate from the meaning of this invention. Needless to say, all of them belong to the category of the present invention.

Hereinafter, representative examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is not limited by the description of such examples. That should also be understood.

-Example 1-
As a flat multi-hole tube according to the present invention, a composite billet ah composed of a tube body material and a sacrificial anode material having the component composition (%: mass basis) shown in Table 1 below is manufactured, and by hot extrusion, Flat multi-hole tubes A to H were obtained respectively. In addition, as a comparative example, a single billet i or a composite billet j having the component composition shown in Table 1 below was manufactured in the same manner, and flat multi-hole tubes I and J were obtained by hot extrusion. Then, using the obtained flat multi-hole tubes A to J, the following (1) measurement of the formation range of the sacrificial anode portion, (2) potential measurement, and (3) corrosion prevention evaluation were performed.

Specifically, first, for various pipe bodies having a diameter of 90 mmφ by DC casting using the pipe body material components in the billets a to h of the present invention and the comparative billet j shown in Table 1 according to a conventional method. A cylindrical billet was prepared. On the other hand, various sacrificial anode billets prepared using the sacrificial anode material components in the billets a to h of the present invention and the comparative billet j shown in Table 1 above, with various vertical and horizontal dimensions in the range of 30 mm to 85 mm. In combination, it was molded and processed to give a predetermined rectangular cross-sectional shape. Note that the sacrificial anode billet in the comparative billet j had a square cross section of 70 mm × 70 mm. Then, a through hole into which the processed sacrificial anode billet can be inserted is formed in the central portion of the cross section of the tube body billet, and the sacrificial anode billet is inserted into the through hole, and further, the tube body A billet for a sacrificial anode and a billet for a sacrificial anode are fixed and joined to each other in the longitudinal direction by MIG welding, and each composite billet ah and j has a cross-sectional form as shown in FIG. A typical composite billet 20 was produced. Further, as a comparative example, a single billet composed of the tube body material components in the comparative billet i shown in Table 1 above was produced. The single billet of the alloy component according to the comparative billet i is a single billet shown as 30 in FIG. 6, which is the same as the conventional material that does not use the sacrificial anode billet. In FIGS. 5 and 6, reference numerals 22 and 32 are tube main body billets, and reference numeral 24 is a sacrificial anode billet.

Subsequently, the composite billet 20 or the single billet 30 thus obtained is heated to 500 ° C. with a billet heater, and then provided with an extrusion port for forming eight rectangular holes (eight flow paths). By using a port hole die similar to that shown in FIG. 1 to perform hot extrusion processing, 8-hole flat multi-hole tubes A to H and I to J (total thickness: 2.0 mm, flat direction) Width: 16 mm, pipe peripheral wall portion and inner partition wall thickness: 0.25 mm), respectively.

(1) Measurement of formation range of sacrificial anode part Various flat multi-hole pipes (10) thus obtained with 8 holes were cut at a half position in the extrusion longitudinal direction, and the cross section was observed. That is, the formation range of the sacrificial anode part (18) was measured by measuring the area of the sacrificial anode part (18) with a ruler using a photograph taken of the microstructure of the cross section at a magnification of 25 times. In the measurement of the formation range of the sacrificial anode part (18), the formation range of the sacrificial anode part (18) is the circumference of the flow path (12) (the total length of the four wall surfaces of the rectangular flow path). ) Was evaluated as (O) when it was 10% or more and (x) when it was 0% or more and less than 10% of the circumference. When the thickness of the sacrificial anode part (18) in the internal partition wall part (16) adjacent to the flow path is more than 0% and not more than 100% of the thickness of the internal partition wall part (16), (◯) is set. In the case of%, it was evaluated as (×). Furthermore, when the thickness of the sacrificial anode part (18) in the pipe peripheral wall part (14) is 90% or less of the thickness of the pipe peripheral wall part (14), (◯), and when it exceeds 90%, (x) ,evaluated. Table 2 below shows the results of measuring the formation range of the sacrificial anode portion 18 for the flat multi-hole tubes A to H according to the present invention and the flat multi-hole tubes I and J according to the comparative example. In the value at which the circumference of the sacrificial anode part (18) exposed at the minimum is shown, and as the maximum thickness of the sacrificial anode part (18) in the inner partition wall part (16) and the pipe peripheral wall part (14) Yes.

As a result of such cross-sectional observation, in the flat multi-hole pipes A to H according to the present invention obtained by the above-described extrusion process, all of the internal partition walls (16) located between the adjacent flow paths (12) It was confirmed that the sacrificial anode part (18) made of the sacrificial anode billet was exposed at a thickness of 100% or less of the thickness of the internal partition wall part (16). Further, the thickness of the sacrificial anode part (18) formed on the pipe peripheral wall part (14) is 80% or less of the thickness of the internal partition wall part (16), and such flat multi-holes are further provided. In all the flow paths (12) of the pipe (10), it was recognized that the sacrificial anode part (18) was exposed in a length range exceeding 0% of the circumference.

Further, in the flat multi-hole tube (10) obtained by hot extrusion in this way, in the longitudinal direction of the extrusion, the sacrificial anode part (18) formed by the sacrificial anode billet has a flow path ( It was also confirmed that it was stably exposed on the inner surface of 12).

On the other hand, the flat multi-hole tube I obtained by carrying out hot extrusion using a porthole die using the single billet 30 of the billet composition i according to the comparative example does not use the sacrificial anode billet. There were no exposed portions of the anode portion 18. Further, the flat multi-hole tube J according to the comparative example obtained from the composite billet j manufactured using the Al-2% Zn billet processed into a square shape of 70 mm × 70 mm as the sacrificial anode billet has a width of It is confirmed that the sacrificial anode portion (18) made of the sacrificial anode billet is exposed at a thickness of 100% or less of the thickness of the internal partition wall portion (16) in the inner partition wall portion (16) at the center in the direction. It was. Moreover, the thickness of the sacrificial anode part (18) formed in the pipe peripheral wall part (14) was 93% of the thickness of the pipe peripheral wall part (14) in the thickest part. However, in the flow path (12) at both ends in the width direction, there is a portion where the sacrificial anode part (18) is not exposed at all, and therefore the peripheral length of the minimum flow path portion is 0%.

(2) Potential measurement Using the flat multi-hole tubes A to H according to the present invention obtained above and the flat multi-hole tubes I and J according to the comparative example, the potentials of the tube body material and the sacrificial anode material are respectively determined. It was measured. In addition, the flat multi-hole pipe I which concerns on a comparative example is manufactured from the single billet comprised only with pipe | tube main body material, and the sacrificial anode part (18) is not formed.

Specifically, for the fin joint when the flat multi-hole tubes A to H according to the present invention and the flat multi-hole tubes I and J according to the comparative example are used as heat transfer tubes in the heat exchanger. Assuming brazing heating, the heat treatment was performed at 600 ° C. for 3 minutes, and then they were each cut to a length of 40 mm in the longitudinal direction of extrusion. Then, the test material for measuring the potential of the tube body material is for measuring the potential on one side of the cut end surface, leaving an exposed surface of the tube body material of 10 mm × 10 mm at the center in the width direction of the outer surface on one side of the peripheral wall. All the parts except for the part connecting the lead wires were masked with silicone resin to be electrically insulated. Further, the test material for measuring the potential of the sacrificial anode portion (18) (sacrificial anode material) was cut to a thickness of ½ at the cut surface extending in the longitudinal direction (tube axis direction) of the flat shape, Masking with silicone resin all but the part where the lead wire for potential measurement is connected to one side of the cut end face, leaving the exposed surface of the sacrificial anode part (18) of 10 mm × 10 mm at the center in the width direction of the half body. Electrically insulated.

As a method for measuring the potential, a saturated KCl calomel electrode (SCE) is used as a reference electrode, while a 5% NaCl aqueous solution adjusted to pH 3 with acetic acid is used as a test solution. A method of measuring each potential after immersing the test material in the solution for 24 hours while stirring at room temperature was employed.

The results of the potential difference between the tube body material and the sacrificial anode material obtained by the above measurement are shown in Table 3 below. In addition, when the potential difference between the tube body material and the sacrificial anode material is 5 mV or more and 300 mV or less, (◎), and when the potential difference exceeds 0 mV and less than 5 mV or exceeds 300 mV, (◯) In the case of 0 mV, it evaluated as (x).

As is clear from the potential measurement results shown in Table 3, the sacrificial anode portion (18) (sacrificial anode material) and the tube body material of the flat multi-hole tubes A to H according to the present invention after the assumed brazing heating. The difference in potential between the first and second electrodes was 3 to 350 mV, and all showed results having an effective sacrificial anode effect.

On the other hand, when the flat multi-hole tube I according to the comparative example is used as a test material, the flat multi-hole tube I according to the comparative example is the same as the conventional material without using a sacrificial anode material. Since it is a flat multi-hole tube composed only of the tube body material, the potential difference was 0 mV.

Moreover, when the same potential measurement as described above was performed using the flat multi-hole tube J according to the comparative example as a test material, the sacrificial anode of the flat multi-hole tube J according to the comparative example after the assumed brazing heating The potential difference between the portion (18) (sacrificial anode material) and the tube body material was 150 mV, which resulted in a sacrificial anode effect.

(3) Evaluation of corrosion resistance Using the flat multi-hole tubes A to H according to the present invention obtained above and the flat multi-hole tubes I and J according to the comparative examples as test materials, an OY water immersion test was conducted. Then, the effect of each inner surface anticorrosion was verified. This OY water immersion test was carried out in 1 L of pure water, sodium chloride: 0.026 g, sodium sulfate (anhydrous): 0.089 g, cupric chloride (dihydrate): 0.003 g, and ferric chloride ( Hexahydrate): In the test solution obtained by dissolving 0.145 g, the above test material was immersed by exposing only the inner surface, held at a temperature of 80 ° C. for 8 hours, and then at room temperature for 16 hours. The internal corrosion resistance is evaluated by setting the time holding as one cycle and repeating the cycle for 30 cycles, 60 cycles or 90 cycles.

Specifically, for the fin joint when the flat multi-hole tubes A to H according to the present invention and the flat multi-hole tubes I and J according to the comparative example are used as heat transfer tubes in the heat exchanger. Assuming brazing heating, heat treatment is performed at 600 ° C for 3 minutes, then they are cut to a length of 100 mm in the longitudinal direction of extrusion, and all of the outer surface and cut end face are masked with silicone resin. By electrically insulating. Next, the test material masked with the silicone resin was immersed in the above OY test solution and immersed for 8 hours at 80 ° C. with stirring, and then for 16 hours in a state where heating and stirring were stopped. By holding it as one cycle and repeating it for 30, 60, or 90 cycles, an anticorrosion evaluation test was conducted in a period of three levels.

For the test materials for which the evaluation test of the anticorrosion property has been completed, after the surface silicone sealant resin is peeled off, it is put into a phosphoric acid chromic acid solution heated at a heater to corrode the surface of the test material. The product was removed, and the presence or absence of through holes on the surface of the test material was examined. Further, the test material from which the corrosion products have been removed is cut to a thickness of ½ on the cut surface extending in the longitudinal direction (tube axis direction) of the flat shape, and the half is filled with the embedded resin. After wrapping, the maximum corrosion portion was cross-sectioned with water-resistant paper, and further mirror-finished by buffing to observe the corrosion state of the inner surface of each sample material. In addition, about the test material used by the said test, in OY water immersion test, penetration does not generate | occur | produce in 60 cycles, and when penetration is seen after 90 cycles, or it is not penetrating, it is set as ((double-circle)), and 30 cycles No penetration occurred, and when penetration was observed after 60 cycles, (◯) was evaluated, and when penetration was observed after 30 cycles, (×) was evaluated.

Table 4 below shows the results of performing the above OY water immersion test in 30, 60, or 90 cycles for the flat multi-hole tubes A to H according to the present invention and the flat multi-hole tubes I and J according to the comparative example. Are shown respectively.

As is clear from the results in Table 4, the flat multi-hole tubes A to H according to the present invention material have no through-holes penetrating the tube peripheral wall portion in the evaluation after 30 cycles of the OY water immersion test. Admitted. Moreover, in the evaluation after 60 cycles, in the flat multi-hole tubes B, C, F, and H, a through-hole penetrating the tube peripheral wall portion was confirmed. Furthermore, in the evaluation after 90 cycles, no through hole was observed in any flat multi-hole tube other than B, C, F, and H. Therefore, it was recognized that the flat multi-hole tubes A to H according to the present invention realized effective inner surface corrosion prevention by the sacrificial anode effect due to the presence of the sacrificial anode portion (18).

On the other hand, the flat multi-hole tube I according to the comparative example is a flat multi-hole tube using only the tube body material similar to the conventional material without using the sacrificial anode material, and therefore, the OY water immersion test is performed 30 times. When 60 and 90 cycles were carried out, it was recognized that corrosion holes penetrating the pipe peripheral wall portion were formed in the evaluation after all the cycles. This is because the sacrificial anode part (18) does not exist around the flow path as in the flat multi-hole tube according to the present invention, so that the sacrificial anode effect cannot be obtained and the inner surface anticorrosive effect cannot be exhibited. It was recognized that penetration occurred early.

In addition, the flat multi-hole tube J according to the comparative example was subjected to the same OY water immersion test as described above for 30, 60, or 90 cycles, and in all the evaluations after the cycle, corrosion holes penetrating the pipe peripheral wall portion were generated. It was recognized that These penetrations were confirmed at both ends in the width direction of the flat multi-hole tube in which the sacrificial anode part (18) was not formed. This is because, like the above flat multi-hole tube I, the sacrificial anode portion (18) does not exist around the flow path, so that the sacrificial anode effect cannot be obtained and the inner surface anticorrosive effect cannot be exhibited. It was recognized that penetration occurred early.

-Example 2-
By using the composite billet a manufactured in Example 1 and carrying out hot extrusion from a port hole die having a different port hole size in the same manner as in Example 1, FIG. 2A or FIG. The flat multi-hole tubes AA to AH as shown in the following Table 5 having 8 rectangular holes (8 flow paths) as shown in FIG. In addition, about those obtained various flat multi-hole pipes, those cross sections are investigated, the thickness (Twi) of the internal partition wall part (16b) on the tube width direction center side, the internal partition wall on the tube width direction end side The thickness (Twe) of the portion (16a), the thickness (Tmin) of the thinnest wall portion of the internal partition wall (16), and the width (Tb) of the upper and lower connecting portions (16c) of the internal partition wall (16). The results are shown in Table 5 below.

Further, for the obtained flat multi-hole tubes AA to AH, the formation range of the sacrificial anode portion (18) in the cross section thereof was measured in the same manner as in Example 1, and the presence state of the sacrificial anode portion (18) was determined. The results are shown in Table 6 below. Furthermore, for each flat multi-hole tube, the same OY water immersion test as in Example 1 was repeated for 30, 60 or 90 cycles to evaluate the anticorrosion properties. The results are also shown in Table 6 below. In the OY water immersion test, penetration does not occur at 60 cycles, but after 90 cycles, when penetration is observed in the internal partition wall portion (16) or not penetrated, (◎), and penetration occurs at 30 cycles. However, when penetration was observed in the internal partition wall (16) after 60 cycles, it was marked with (◯). When penetration was observed in the internal partition wall (16) after 30 cycles, (× ) And evaluated.

As shown in Table 6, each of the flat multi-hole tubes AA to AH has the presence of the sacrificial anode portion (18) in the tube peripheral wall portion (14) that divides the flow path (12a) located at both ends. While the pipe body material is exposed on the inner surface of the flow path, the end inner partition wall section that divides the flow path (12a) located at both ends from the flow path (12b) located next thereto ( In 16a), the sacrificial anode part (18) is formed in a thickness corresponding to the thickness, and the exposure ratio of the sacrificial anode part (18) occupying the entire circumference of the end channel (12a). Was 20%. In addition, the sacrificial anode part (18) existing in the pipe peripheral wall part (14) that defines the flow path (12b) located outside the both ends in the width direction of the flat multi-hole tube is 0%, and is on the inner surface of the flow path. Is a sacrificial anode at a rate of 100% corresponding to the thickness of the internal partition wall portion (16b) that defines the flow channel (12b) located outside the both ends in the width direction of the flat tube while the tube body material is exposed The minimum value of the exposed (existing) region of the sacrificial anode portion (18) occupying the entire circumference of the channel (12b) was 50%.

Then, as a result of the OY water immersion test for the flat multi-hole pipes AA to AH, the occurrence of corrosion holes penetrating through the pipe peripheral wall (14) after the 90-cycle repeated test for any flat multi-hole pipe. Was not recognized.

Regarding the corrosion of the internal partition wall (16) in each flat multi-hole tube, in the flat multi-hole tube AA, AE and AG, the internal partition wall partitioning the flow path (12a) located at the end in the width direction. It was confirmed that the sacrificial anode part (18) in (16a) was preferentially corroded, and corrosion holes penetrating through the internal partition wall part (16a) were formed after 30 cycles in the OY water immersion test. And in flat multi-hole pipe AB thru | or AD and AF, the thickness (Twe) of the internal partition part (16a) which divides the flow path (12a) located in the both ends of a multi-hole pipe width direction is such It is located thicker than the thickness (Twi) of the internal partition wall portion (16b) positioned at the center of the multi-hole tube width direction than the internal partition wall portion (16a). Therefore, even after 60 cycles of the OY water immersion test, no through-hole due to corrosion was generated, and even after 90 cycles, some flat multi-hole pipes had internal partition walls (16a) at their ends. It was confirmed that there were no corrosion holes penetrating.

Furthermore, in the flat multi-hole pipes AG and AH, since the width of the connecting part (16c) of the internal partition wall part (16) is not sufficient, the pipe exposed in the flow path (12) in the pipe peripheral wall part (14). Due to the potential difference from the main body material, the upper and lower connecting portions (16c) of the inner partition wall (16) are preferentially corroded, and therefore, through corrosion of the inner partition wall (16) after 30 cycles of the OY water immersion test. Admitted. On the other hand, in the flat multi-hole tubes AD to AF, the width (Tb) of the upper and lower connecting portions (16c) of the inner partition wall (16) is the minimum wall thickness ( Since it is configured to be larger than (minimum width) Tmin, preferential corrosion of the sacrificial anode portion (18) located on the connecting portion (16c) side of the internal partition wall portion (16) is advantageously suppressed, and an OY water immersion test is performed. After 60 cycles, no through-corrosion holes were found in the internal partition wall (16), and even after 90 cycles, the existence of such through-corrosion holes was observed in some flat multi-hole pipes. I couldn't.

10 flat multi-hole tube 12 flow path (hole)
14 pipe peripheral wall part 16 inner partition part 18 sacrificial anode part 20 composite billet 30 single billet 22, 32 pipe body billet 24 sacrificial anode billet

Claims (8)

An extruded tube having a flat cross-sectional shape as a whole obtained by extrusion of an aluminum material, and having a plurality of channels extending in parallel with each other in the tube axis direction, and these channels are tubes An aluminum extruded flat multi-hole tube arranged in the longitudinal direction of the flat shape through an internal partition extending in the axial direction,
The aluminum material is formed by an extrusion process using an aluminum tube main body material and an aluminum sacrificial anode material that is electrochemically less basic than the aluminum tube main body material, and in each cross section of the plurality of flow paths. An aluminum extruded flat multi-hole tube excellent in internal corrosion resistance, wherein the sacrificial anode part is formed by exposing the aluminum sacrificial anode material in at least a part of the inner periphery of the flow path. The said sacrificial anode part is made to exist in the ratio of 100% or less of the thickness of this internal partition part in the said internal partition part located between the adjacent thing of these several flow paths. Aluminum extruded flat multi-hole tube. 3. The aluminum extruded flat structure according to claim 1, wherein the sacrificial anode portion is present at a ratio of 90% or less of the thickness of the tube peripheral wall portion in a tube peripheral wall portion other than the inner partition wall portion. Hole tube. The aluminum extruded flat multi-hole tube according to any one of claims 1 to 3, wherein a potential difference between the aluminum sacrificial anode material and the aluminum tube main body material is 5 mV or more and 300 mV or less. The sacrificial anode portion is formed over a length of at least 10% of the circumferential length of the flow path in the cross section of the tube and exposed to the inner surface of the flow path. An aluminum extruded flat multi-hole tube according to any one of the preceding claims. Of the internal partition walls existing between adjacent ones of the plurality of flow paths, the internal partition walls positioned at both ends in the longitudinal direction of the flat shape are thicker than the other internal partition walls, respectively. The aluminum extruded flat multi-hole tube according to any one of claims 1 to 5, wherein The internal partition wall located between adjacent ones of the plurality of flow paths is continuously or stepwise from the thinnest part of the wall thickness toward the pipe peripheral wall on both sides connected by the internal partition wall 2. The wall thickness of the inner partition wall portion is increased by a connecting portion having a thickness greater than that of the thinnest wall thickness portion of the inner partition wall portion. The aluminum extruded flat multi-hole tube according to any one of claims 6 to 6. The aluminum extruded flat multi-hole tube according to any one of claims 1 to 7, and an aluminum outer fin brazed to the outer surface of the aluminum extruded flat multi-hole tube. An aluminum heat exchanger characterized by that.

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