JP2015167990A - Grooved plug, extrusion die, heat transfer tube manufacturing method, and heat transfer tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grooved plug, an extrusion die, a heat transfer tube manufacturing method, and a heat transfer tube capable of suppressing the cracking of the heat transfer tube.SOLUTION: In a grooved plug 25 for forming a plurality of grooves 90 and 91 in an axial direction of an inner wall of a heat transfer tube 44 by extrusion, a plurality of protrusions 80 and 92 is formed at intervals in a circumferential direction for forming the grooves 90 and 91, and the protrusions 80 in a plurality of portions out of the protrusions 80 and 92 are formed such that a height position H1 of an upper end of the protrusions 80 is lower than a height position H2 of an upper end of the other protrusions 92.

Description

  The present invention relates to a heat transfer tube with an inner surface groove, which is a piping part of a heat exchanger used in an air conditioner, a method for manufacturing the heat transfer tube, a grooved plug for forming a heat transfer tube with an inner surface groove, and an extrusion die. The crack of the heat transfer tube can be suppressed.

  In recent years, as heat transfer tubes with grooves on the inner surface of heat exchangers (so-called finned tube heat exchangers) for air conditioners (such as air conditioners), the inner surface has been improved by forming numerous grooves and fins in the tube inner surface. Grooved heat transfer tubes are often used.

  In conventional heat transfer tubes with inner surface grooves, the dimensions such as the height of the fins in the tube of the groove shape are devised to suppress crushing of the fin shape in the tube of the heat transfer tubes with inner surface grooves and to improve heat transfer performance (for example , Refer to Patent Document 1), and devise the width of the protrusion of the grooved die and the shape of the tip R to suppress the defect of the heat transfer tube with the groove on the inner surface and the manufacturing failure in the subsequent process (for example, patents) Reference 2).

JP 2010-133668 A JP 2007-218566 A

  In a conventional heat transfer tube with an inner surface groove, in the manufacturing process of the heat exchanger, a tube expansion step of expanding the inner surface grooved heat transfer tube inserted into the plurality of heat transfer fins and closely contacting the through hole of the heat transfer fin, and A problem that local cracks occur in the inner surface grooved heat transfer tube in the process of expanding the inlet of the inner surface grooved heat transfer tube when inserting and brazing U-tubes and connecting the pipes to form a pipe line There was a point.

  The present invention has been made to solve the above-described problems, and is provided with a grooved plug, an extrusion die, a method for manufacturing a heat transfer tube, and a heat transfer tube that can suppress defects that cause cracks in the inner surface grooved heat transfer tube. The purpose is to provide a heat pipe.

The grooved plug of this invention is
In the grooved plug for forming a plurality of grooves in the axial direction of the inner wall of the heat transfer tube by extrusion,
A plurality of protrusions are formed at intervals in the circumferential direction to form a plurality of the grooves,
Among the plurality of protrusions, the height positions of the upper ends of the plurality of protrusions are formed lower than the height positions of the other upper ends of the protrusions.

The grooved plug of the present invention is
In the grooved plug for forming a plurality of grooves in the axial direction of the inner wall of the heat transfer tube by extrusion,
A plurality of protrusions are formed at intervals in the circumferential direction to form a plurality of the grooves,
Among the plurality of protrusions, the interval in the circumferential direction of the plurality of protrusions is formed larger than the interval in the circumferential direction of the other protrusions,
The positions of the lower ends of the plurality of protruding portions are formed at the same height or higher than the positions of the lower ends of the other protruding portions.

The extrusion die of the present invention is
A molding hole into which a grooved plug for molding the extruded material is inserted; and
A plurality of metal holes that are formed on the upstream side of the molding hole along the extrusion direction, and are formed at intervals in the circumferential direction;
An extrusion die having a plurality of bridges respectively provided between two metal holes adjacent in the circumferential direction,
The grooved plug is the grooved plug described above,
The circumferential formation positions of the protrusions at the plurality of locations of the grooved plug are formed at the same positions as the circumferential formation positions at which the plurality of bridges are formed.

Moreover, the manufacturing method of the heat exchanger tube of this invention is as follows.
The extrudate is extruded from the extrusion die described above, and the heat transfer tube having the plurality of grooves is manufactured.

The heat transfer tube of the present invention is
In the heat transfer tube having a plurality of grooves in the axial direction of the inner wall,
Of the plurality of grooves, the depth positions of the lower ends of the grooves at a plurality of locations are formed shallower than the depth positions of the lower ends of the other grooves.

The heat transfer tube of the present invention is
In the heat transfer tube having a plurality of grooves in the axial direction of the inner wall,
Among the plurality of grooves, the width in the circumferential direction of the side wall of the plurality of grooves is formed larger than the width in the circumferential direction of the side wall of the other groove,
The positions of the upper ends of the side walls of the plurality of grooves are formed at the same height as or lower than the positions of the upper ends of the side walls of the other grooves.

Since the grooved plug, extrusion die, heat transfer tube manufacturing method and heat transfer tube of the present invention are configured and performed as described above,
In the expansion process of the heat transfer tube with the inner surface groove, it is possible to suppress a defect in which a crack occurs in the heat transfer tube.

It is a top view which shows the structure of the grooved plug of Embodiment 1 of this invention. It is a top view which shows the structure of the heat exchanger tube with an inner surface groove | channel manufactured using the plug with a groove | channel shown in FIG. It is sectional drawing which shows the structure of the extrusion processing apparatus provided with the extrusion die which has a plug with a groove | channel shown in FIG. It is a top view which shows the structure of the male die of the extrusion die shown in FIG. It is a top view which shows the structure of the female die of the extrusion die shown in FIG. It is a top view which shows the structure of the grooved plug for demonstrating the problem of this invention. It is a top view which shows the structure of the heat exchanger tube with an inner surface groove | channel manufactured using the plug with a groove | channel shown in FIG. FIG. 7 is an enlarged plan view showing a deteriorated state of the grooved plug shown in FIG. 6. It is an enlarged plan view which shows the structure of the heat exchanger tube with an inner surface groove | channel manufactured using the plug with a groove | channel shown in FIG. It is sectional drawing which shows the pipe expansion process of a heat exchanger tube. It is a top view which shows the structure of the grooved plug of Embodiment 2 of this invention. It is a top view which shows the structure of the heat exchanger tube with an inner surface groove | channel manufactured using the plug with a groove | channel shown in FIG. It is a top view which shows the structure of the grooved plug of Embodiment 3 of this invention. It is a top view which shows the structure of the heat exchanger tube with an inner surface groove | channel manufactured using the plug with a groove | channel shown in FIG. It is a top view which shows the structure of the grooved plug of Embodiment 4 of this invention. It is a top view which shows the structure of the heat exchanger tube with an inner surface groove | channel manufactured using the plug with a groove | channel shown in FIG. It is a top view which shows the structure of the other grooved plug of Embodiment 4 of this invention. It is a top view which shows the structure of the heat exchanger tube with an inner surface groove | channel manufactured using the plug with a groove | channel shown in FIG.

Embodiment 1 FIG.
Embodiments of the present invention will be described below. FIG. 1 is a plan view showing a configuration of a grooved plug according to Embodiment 1 of the present invention. FIG. 2 is a plan view showing a configuration of a heat transfer tube with an inner groove manufactured using the grooved plug shown in FIG. FIG. 3 is a cross-sectional view showing a configuration of an extrusion processing apparatus including an extrusion die having the grooved plug shown in FIG. FIG. 4 is a plan view showing the configuration of the male die of the extrusion die shown in FIG. FIG. 5 is a plan view showing the configuration of the female die of the extrusion die shown in FIG.

  FIG. 6 is a plan view showing the configuration of the grooved plug for explaining the problems of the present invention. FIG. 7 is a plan view showing the configuration of a heat transfer tube with an inner groove manufactured using the grooved plug shown in FIG. FIG. 8 is an enlarged plan view showing a deteriorated state of the grooved plug shown in FIG. FIG. 9 is an enlarged plan view showing the configuration of a heat transfer tube with an inner groove manufactured using the grooved plug shown in FIG. FIG. 10 is a cross-sectional view showing a heat transfer tube expansion step.

  In FIG. 1, the grooved plug 24 used for extrusion is formed with a plurality of protrusions 92, 80 at equal intervals in the circumferential direction for forming a plurality of grooves 90, 91 in the axial direction of the inner wall of the heat transfer tube 44. Is done. And in this Embodiment 1, the height position H1 of the upper end of the projection part 80 of several places among the several projection parts 92 and 80, here three places equally (every 120 degree | times) is as follows. The other protrusions 92 are formed lower than the height position H2 of the upper end. The axial direction of the heat transfer tube 44 is a direction with the center B shown in FIG. 2 as an axis. Since this is the same in the embodiments described below, the description thereof will be omitted as appropriate.

  Further, the positions of the lower ends 92a, 80a of the plurality of protrusions 92, 80 are formed at the same height position H5. Note that the height positions H1 and H2 of the upper ends of the protrusions 80 and 92 and the height positions H5 of the lower ends 92a and 80a of the protrusions 92 and 80 are also apparent from FIG. The position (distance) from the center A of the grooved plug 24 is shown. In addition, the relationship between the positions (distances) is the same in the following embodiments, and the description thereof will be omitted as appropriate.

  The heat transfer tube 44 formed by extrusion using the grooved plug 24 has a plurality of grooves 90 and 91 in the axial direction of the inner wall, as shown in FIG. Of the plurality of grooves 90, 91, the depth position H3 of the lower ends of the grooves 90 at three locations (here, every 120 degrees) equally in the same circumferential direction as the previous grooved plug 24 is It is formed shallower than the depth position H4 at the lower end of the groove 91 other than the above. Therefore, the portion where the groove 90 is formed and the tube thickness h3 of the thick portion 90b are formed thicker than the portion where the groove 91 is formed and the tube thickness h4 of the thick portion 91b.

  Further, the positions of the upper ends 91a, 90a of the plurality of grooves 91, 90 are formed at the same height position H6. Note that the depth positions H4 and H3 of the grooves 91 and 90 and the height positions H6 of the upper ends 91a and 90a of the grooves 91 and 90 here are as shown in FIG. The position (distance) from the center B is shown. In addition, the relationship between the positions (distances) is the same in the following embodiments, and the description thereof will be omitted as appropriate.

  The extrusion apparatus 1 in which the extrusion die 2 having the grooved plug 24 configured as described above is used will be described with reference to FIG. However, the extrusion apparatus 1 is an example, and even if it has a configuration other than that shown in this figure, the same effect can be obtained as long as it can be similarly extruded using the grooved plug 24. Therefore, the description thereof is omitted as appropriate.

  The extrusion apparatus 1 includes a container 12 filled with a billet 40 as a metal extrusion material, a block 11 that presses the billet 40 in the container 12, and a ram 10 that moves the block 11 and presses the billet 40. And an extrusion die 2 disposed on the side where the billet 40 of the container 12 is extruded. The extrusion die 2 has a male die 20 disposed on the upstream side provided with a grooved plug 24 for forming the billet 40 on the extrusion side, and the grooved plug 24 is inserted as shown in FIG. A forming hole 13 having a metal hole 32 is formed with a female die 30 disposed on the downstream side.

  Then, as shown in FIG. 4, the male die 20 penetrates along the extrusion direction on the upstream side of the grooved plug 24 and is spaced evenly at three locations (every 120 degrees) in the circumferential direction. Are formed, and a plurality of bridges 29 provided between two metal holes 31 adjacent in the circumferential direction are formed. Therefore, these bridges 29 are formed at three equal intervals in the circumferential direction (every 120 degrees). And the formation position of the circumferential direction of the several projection part 80 of the grooved plug 24 is arrange | positioned so that it may become the same position as the formation direction of the circumferential direction in which the some bridge | bridging 29 is formed.

  Next, the manufacturing method of the heat exchanger tube 44 using the extrusion processing apparatus 1 provided with the grooved plug 24 of Embodiment 1 comprised as mentioned above is demonstrated. First, by pressurizing the ram 10 in the extrusion direction X, the heated billet 40 loaded in the container 12 is passed through the molding hole 13 between the male die 20 and the female die 30. In this extrusion process, the billet 40 is divided by the three metal holes 31 of the male die 20, and the forming hole 13 between the grooved plug 24 of the male die 20 and the metal hole 32 of the female die 30. Until it passes.

  This joining phenomenon is called welding, and the joining part is called a welding part. In the extrusion process of the extrusion apparatus 1, the forming hole 13 of the female die 30 having the grooved plug 24 having the projections 80 and 92 and the circular metal hole 32 for forming the outer peripheral surface as shown in FIG. By passing the material of the billet 40 between the grooves 90 and 91 and the upper end 90a of the groove 90 as the inner fin and the upper end 91a of the groove 91 on the inner peripheral surface as shown in FIG. A heat tube 44 is formed. That is, the formation positions in the circumferential direction of the thick portions 90 b of the grooves 90 in the plurality of places of the heat transfer tubes 44 are formed in the same places as the formation positions in the circumferential direction of the bridge 29.

  Here, problems solved by the present invention will be described. First, unlike the present invention, as shown in FIG. 6, the grooved plug 22 used in the extrusion process forms a plurality of grooves 94 in the axial direction of the inner wall of the heat transfer tube 42, and therefore is the same at equal intervals in the circumferential direction. A case where a plurality of protrusions 93 having a shape are formed will be described. Therefore, the height position H2 of the upper ends of all the protrusions 93 and the height position H5 of the lower ends 93a of all the protrusions 93 are all formed at the same height position.

  Therefore, as shown in FIG. 7, the heat transfer tube 42 formed by extrusion using the grooved plug 22 has all the grooves 94 at equal intervals in the circumferential direction. The depth position H4 and the height position H6 of the upper end 94a of the groove 94 are formed at the same height position. Therefore, the tube thickness h4 where the groove 94 is formed is formed with the same thickness in all.

  When the grooved plug 22 formed in this way is arranged in the extrusion apparatus 1 in the same manner as in the first embodiment and the heat transfer tube 42 is formed, in the extrusion process of the extrusion apparatus 1, The material of the billet 40 is allowed to pass through the forming hole 13 of the female die 30 having the grooved plug 22 having the projection 93 as shown in FIG. 6 and the circular metal hole 31 forming the outer peripheral surface, as shown in FIG. The inner surface grooved heat transfer tube 42 having the groove 94 and the upper end 94a of the groove 94 as the tube fin is formed on the inner peripheral surface.

  When this heat transfer tube 42 is incorporated into, for example, a heat exchanger, the ends of the heat transfer tubes 42 arranged in parallel are inserted into a U-shaped tube and connected by brazing or the like, and the pipes in the heat exchanger are connected. At this time, as shown in FIG. 10, a secondary tube expansion tool 60 having a tapered portion and a diameter larger than the inner diameter of the heat transfer tube 42 is inserted into the tube opening of the heat transfer tube 42 so that the U-shaped tube can be inserted. The inner diameter of the end portion of the heat tube 42 is expanded. At this time, in the tube expansion process of expanding the tube port of the heat transfer tube 42, the tube port of the heat transfer tube 42 may crack and become defective.

  In the present inventor, the heat transfer tube 42 cracked at the tube opening was verified in detail. Then, as shown in FIG. 9, the heat transfer tube 42 had a thick portion 52 having a large tube thickness like a lower portion of the groove 940 and a thin portion 51 having a thin tube thickness like a lower portion of the groove 94. Furthermore, it has been found that the thin-walled portion 51 is present at three locations on the circumference of the heat transfer tube 42 at equal angular intervals. Due to the presence of the thin wall portion 51, the thin wall portion 51 is subjected to stress compared with the surrounding thick wall portion 52 in the pipe expanding step for expanding the tube opening portion of the heat transfer tube 42 as shown in FIG. growing.

  Accordingly, the elongation at the time of pipe expansion in the thin portion 51 is larger than that in the surrounding thick portion 52. And in the heat exchanger tube 42, since the thin part 51 was only three places in the circumferential direction, it discovered that this elongation (stress) concentrated on the thin part 51, and resulted in the crack. In particular, it has been found that this phenomenon occurs remarkably in the case of the aluminum heat transfer tube 42 due to the property that work hardening is smaller than that of the copper heat transfer tube 42.

  As a result of going back this process and verifying and investigating the extrusion process, as shown in FIG. 8, the grooved plug 22 is a protrusion 93 that is not changed from the initial state, and the protrusion becomes worn and smaller than the initial state. 930 was found to exist. Further, it has been found that there are three projections 93 in the initial state at equal angular intervals on the circumference of the grooved plug 22. These three places are generated at the place where the billet 40 is divided into three parts by the metal hole 31 and the bridge 29 of the male die 20 shown in FIG. 4 and the three parts are welded before passing through the forming hole 13 of FIG. I found out that It was also found that the amount of wear increased with the amount of extrusion of the billet 40.

  In this way, the protrusion 93 of the grooved plug 22 is less worn compared to the other protrusions 930 at the position corresponding to the bridge 29 where the billet 40 is split and joined again. I found. When the heat transfer tube 42 is formed by the projections 93 and 930 of the worn grooved plug 22, the thickness of the projection 93 becomes a thin portion 51. And it became clear that when the heat transfer tube 42 had several thin portions 51 locally and locally, and the heat transfer tube 42 was expanded, stress and elongation were concentrated locally, and a defect that caused cracks occurred locally.

  In order to solve this problem, the grooved plug 24 as shown in FIG. 1 is formed in the present invention. And this grooved plug 24 formed three protrusions 80 at a plurality of locations at equal angular intervals on the circumference. The plurality of projecting portions 80 are aligned with the position of the bridge 29 which is a location where the billet 40 is divided by the male die 20 to form a welded portion. As a result, even when wear occurs in the protrusions 92 in other locations other than the plurality of protrusions 80, the plurality of protrusions 80 are formed low in advance, so that many billets 40 are extruded. Even in this case, inconvenience is less likely to occur.

  Therefore, since the life of the extrusion die 2 can be extended by the grooved plug 24, the jig replacement frequency and the jig cost can be suppressed. Further, as shown in FIG. 2, the heat transfer tube 44 formed by the grooved plug 24 has thick portions 90b at only three locations of the heat transfer tube 44, and therefore a tube expansion process as shown in FIG. In this case, the stress is not concentrated only in the three thick portions 90b of the heat transfer tube 44, and the elongation can be dispersed in the other thick portions 91b, thereby suppressing the occurrence of product defects due to the occurrence of cracks. be able to.

  In addition, since the heat transfer tube 44 is configured with a heat exchanger, the heat transfer tube 44 is locally stressed and is not stretched. Therefore, the thickness of the heat transfer tube 44 is suppressed from being reduced, and the heat transfer tube 44 is strong against internal pressure. Can be increased. Note that the material of the heat transfer tube 44 is not limited to a specific material such as copper, copper alloy, aluminum, or aluminum alloy, but is made of any metal material.

  According to the grooved plug, the extrusion die, the heat transfer tube manufacturing method, and the heat transfer tube of Embodiment 1 configured as described above, the transfer of the material where the material is welded in the extrusion process is divided by the bridge and joined again. Heat transfer tube formed with a grooved plug by making the height of the projection of the grooved plug forming the groove shape of the heat tube lower than the height of the projection of the other portion where wear increases other than the welded portion It is possible to prevent the tube thickness from becoming thin locally. Since the tube thickness of the heat transfer tube is not locally reduced, the heat transfer tube can suppress local concentration of stress and elongation in the circumferential direction in the tube expansion process. Thereby, generation | occurrence | production of the crack defect in the pipe opening part of a heat exchanger tube can be suppressed in the pipe expansion process at the time of manufacture.

Embodiment 2. FIG.
FIG. 11 is a plan view showing the configuration of the grooved plug according to the second embodiment of the present invention. FIG. 12 is a plan view showing the configuration of a heat transfer tube with an inner groove manufactured using the grooved plug shown in FIG. In the figure, the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the second embodiment, the number of grooves or protrusions at a plurality of locations is one in the first embodiment, whereas in the embodiment 2, the grooves or protrusions at a plurality of locations are circumferential. A plurality, in this case, three are formed in the direction. As in the first embodiment, the circumferential formation position where each bridge 29 of the extrusion die is formed and the circumferential formation position of the three consecutive protrusions 80 are the same position. It is formed. Therefore, the heat transfer tube 45 formed by the grooved plug 25 in the same manner as in the first embodiment has a plurality of grooves 90 at a plurality of locations in the circumferential direction, in this case, three in succession.

  According to the grooved plug, the extrusion die, the heat transfer tube manufacturing method, and the heat transfer tube of the second embodiment configured as described above, the same effects as those of the first embodiment can be obtained. Since a plurality of grooves or projections are formed continuously, even if the position of the welded portion varies in the extrusion process, it corresponds to several places in the heat transfer tube welding, so it is locally thick. Can be further prevented from becoming thinner.

Embodiment 3 FIG.
FIG. 13 is a plan view showing the configuration of the grooved plug according to Embodiment 3 of the present invention. FIG. 14 is a plan view showing the configuration of a heat transfer tube with an inner groove manufactured using the grooved plug shown in FIG. In the figure, the same parts as those in the above embodiments are denoted by the same reference numerals, and description thereof is omitted. In each of the above embodiments, the plurality of protrusions 80 are formed in one or a plurality of consecutive three locations as a plurality of locations in each of the above embodiments, whereas in the present embodiment 3, The grooved plug 26 has the projections 80 formed at a plurality of five locations in the circumferential direction.

  Unlike the above embodiments, the metal holes of the extrusion dies are formed evenly in five locations in the circumferential direction, whereby the bridges are formed evenly in the circumferential direction (every 72 degrees). Because. Therefore, the circumferential formation positions of the five bridges and the circumferential formation positions of the protrusions 80 are formed at the same position.

  In the heat transfer tube 46 formed by the grooved plug 26 in the same manner as in the above embodiments, one groove 90 is formed at each of a plurality of five locations (every 72 degrees) in the circumferential direction. As in the second embodiment, a plurality of grooves 90 can be continuously formed in a plurality of locations in the circumferential direction.

  According to the grooved plug, extrusion die, heat transfer tube manufacturing method, and heat transfer tube of the third embodiment configured as described above, even if many metal holes are formed, By responding similarly, the same effect can be produced.

  In addition, although the case where a metal hole is formed in 5 places and a bridge is formed in 5 places was shown here, it is not restricted to this, The formation place of a bridge is 2, 4, 6, 7, 8 places Even if it is, etc., the effect similar to each said embodiment can be show | played by comprising a projection part similarly to said each embodiment. In addition, since it is the same in the following embodiments that the projecting portion is formed corresponding to the bridge forming location, the description thereof will be omitted as appropriate.

Embodiment 4 FIG.
FIG. 15 is a plan view showing the configuration of the grooved plug according to the fourth embodiment of the present invention. FIG. 16 is a plan view showing the configuration of a heat transfer tube with an inner groove manufactured using the grooved plug shown in FIG. In the figure, the same parts as those in the above embodiments are denoted by the same reference numerals, and description thereof is omitted. In each said embodiment, the depth position of the lower end of the groove | channel of the heat exchanger tube corresponding to the formation location of a bridge is formed shallower than the depth position of the lower end of the other groove | channel other than that. Thereby, the example which respond | corresponds by making the tube thickness of the heat exchanger tube corresponding to the formation location of a bridge into a thick part from the tube thickness of another location was shown.

  In the fourth embodiment, the width of the side wall of the groove of the heat transfer tube corresponding to the place where the bridge is formed is formed to be larger than the width of the side wall of the groove at other places. Thus, an example will be described in which the tube thickness of the heat transfer tube corresponding to the place where the bridge is formed is made thicker than the tube thickness of other portions.

  The grooved plug 27 for forming the plurality of grooves 95 in the axial direction of the inner wall of the heat transfer tube 47 by extrusion processing has a plurality of protrusions 81 formed at intervals in the circumferential direction to form the plurality of grooves 95. Of the plurality of protrusions 81, the circumferential interval H7 of the plurality of protrusions 81 is formed larger than the circumferential interval H8 of the other protrusions 81. Furthermore, the height position H5 of the lower end 81a of the plurality of protruding portions 81 is formed at the same height position as the height position H5 of the lower end 81b of the other protruding portions 81.

  Further, in the heat transfer tube 47 formed by extrusion using the grooved plug 27, the circumferential width H <b> 9 of the side wall 95 a of the plurality of grooves 95 among the plurality of grooves 95 is the side wall of the other groove 95. It is formed larger than the circumferential width H10 of 95b. Furthermore, the height position H6 of the upper end of the side wall 95a of the plurality of grooves 95 and the height position H6 of the upper end of the side wall 95b of the other grooves 95 are formed at the same height position. Therefore, in the heat transfer tube 47, a thick portion 95c having a large tube thickness is formed at a portion having a circumferential width H9. And the thick part 95d of the location where thickness is smaller than the thick part 95c is each formed in the location of the width | variety H10 other than that.

  In the fourth embodiment, in the grooved plug 27, the circumferential formation positions of the protrusions 81 at a plurality of locations where the circumferential interval H7 increases are the bridges of the extrusion apparatus shown in each of the above embodiments. Is formed at the same position as the formation position in the circumferential direction. Therefore, the formation position in the circumferential direction of the thick portion 95c of the portion having a large thickness portion due to the width H9 in the circumferential direction of the plurality of grooves 95 of the heat transfer tube 47 is formed in the same location as the formation position in the circumferential direction of the bridge 29. Will be.

  Therefore, as in the above-described embodiments, the heat transfer tube 47 formed by the grooved plug 27 has thick portions 95c at only three locations of the heat transfer tube 47 as shown in FIG. In the tube expansion process as shown in FIG. 10, stress is not concentrated only in the three portions of the thick portion 95c of the heat transfer tube 47, and the elongation can be dispersed in the other thick portion 95d. The occurrence of product defects due to the occurrence can be suppressed.

  According to the grooved plug, the extrusion die, the heat transfer tube manufacturing method, and the heat transfer tube of the fourth embodiment configured as described above, a wide thick portion is formed, and the same as in the above embodiments. By doing so, the same effect can be produced.

  In the fourth embodiment, the height positions H5 of the lower ends 81a of the plurality of protrusions 81 are formed to be the same as the height positions H5 of the lower ends 81b of the other protrusions 81. In this example, the height position H6 of the upper end of the side wall 95a of the groove 95 and the height position H6 of the upper end of the side wall 95b of the other groove 95 are formed at the same height position.

  However, the present invention is not limited to this, and as shown in FIGS. 17 and 18, the grooved plug 28, the height position H 11 of the lower end 81 c of the plurality of protrusions 81, and the other protrusions 81 other than that. The lower end 81b is formed higher than the height position H5. Then, the heat transfer tube 48 is formed such that the height position H12 at the upper end of the side wall 95e of the plurality of grooves 95 is lower than the height position H6 at the upper end of the side wall 95b of the other grooves 95. And the thick part 95f is formed only in three places of the heat exchanger tube 48. FIG. Even in this case, the same effects as those of the third embodiment can be obtained, and the thickness of the heat transfer tubes at a plurality of locations is further thicker than the thickness of the other locations, thereby further preventing a decrease in strength. be able to.

  It should be noted that the present invention can be freely combined with each other within the scope of the invention, and each embodiment can be appropriately modified or omitted.

DESCRIPTION OF SYMBOLS 1 Extrusion processing apparatus, 2 extrusion dies, 10 rams, 11 blocks, 12 containers, 13 molding holes, 20 male type dies, 22 grooved plugs, 24 grooved plugs,
25 grooved plug, 26 grooved plug, 27 grooved plug, 28 grooved plug,
29 bridges, 30 female dies, 31 metal holes, 32 metal holes,
40 billets, 42 heat transfer tubes, 44 heat transfer tubes, 45 heat transfer tubes, 46 heat transfer tubes,
47 Heat transfer tube, 48 Heat transfer tube, 51 Thin part, 52 Thick part, 60 Secondary tube expansion tool,
80 protrusion, 80a lower end, 81 protrusion, 81a lower end, 81b lower end, 90 groove, 90a upper end, 90b thick part, 91 groove, 91a upper end, 91b thick part,
92 protrusion, 92a lower end, 93 protrusion, 93a lower end, 930 protrusion,
94 groove, 94a upper end, 940 groove, 95 groove, 95c thick part, 95d thick part,
H1 height position, H2 height position, H3 depth position, H4 depth position, H5 height position, H6 height position, H7 distance, H8 distance, H9 width, H10 width, H11 depth position, H12 height Position, h3 tube thickness, h4 tube thickness.

Claims (10)

In the grooved plug for forming a plurality of grooves in the axial direction of the inner wall of the heat transfer tube by extrusion,
A plurality of protrusions are formed at intervals in the circumferential direction to form a plurality of the grooves,
Among the plurality of protrusions, a grooved plug is formed such that the height positions of the upper ends of the plurality of protrusions are lower than the height positions of the other upper ends of the other protrusions. The grooved plug according to claim 1, wherein a plurality of the plurality of protrusions are continuously formed in a circumferential direction. In the grooved plug for forming a plurality of grooves in the axial direction of the inner wall of the heat transfer tube by extrusion,
A plurality of protrusions are formed at intervals in the circumferential direction to form a plurality of the grooves,
Among the plurality of protrusions, the interval in the circumferential direction of the plurality of protrusions is formed larger than the interval in the circumferential direction of the other protrusions,
The grooved plug is formed such that the positions of the lower ends of the plurality of protruding portions are the same height or higher than the positions of the lower ends of the other protruding portions. The grooved plug according to claim 1 or 2, wherein positions of lower ends of the plurality of protrusions are formed at the same height position. A molding hole into which a grooved plug for molding the extruded material is inserted; and
A plurality of metal holes that are formed on the upstream side of the molding hole along the extrusion direction, and are formed at intervals in the circumferential direction;
An extrusion die having a plurality of bridges respectively provided between two metal holes adjacent in the circumferential direction,
The grooved plug is the grooved plug according to any one of claims 1 to 4,
The extrusion die formed in the circumferential position where the plurality of projections in the plurality of locations of the grooved plug are formed in the circumferential direction where the plurality of bridges are formed. The manufacturing method of the heat exchanger tube which extrudes the said extrusion material from the extrusion die of Claim 5, and manufactures the said heat exchanger tube which has the said some groove | channel. In the heat transfer tube having a plurality of grooves in the axial direction of the inner wall,
Among the plurality of grooves, heat transfer tubes are formed such that the depth positions of the lower ends of the grooves at a plurality of locations are shallower than the depth positions of the lower ends of the other grooves. The heat transfer tube according to claim 7, wherein a plurality of the plurality of grooves are continuously formed in a circumferential direction. In the heat transfer tube having a plurality of grooves in the axial direction of the inner wall,
Among the plurality of grooves, the width in the circumferential direction of the side wall of the plurality of grooves is formed larger than the width in the circumferential direction of the side wall of the other groove,
The position of the upper end of the said side wall of the said groove | channel of several places is the heat exchanger tube formed in the same height position or low as the position of the upper end of the said other side of the said groove | channel other than that. The heat transfer tube according to claim 7 or 8, wherein positions of upper ends of the plurality of grooves are formed at the same height position.

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