JP2009220153A - Method of manufacturing tube with spirally grooved inside surface and its device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a tube having a spirally grooved inside surface which is manufactured with a device having simple structure and has high productivity and its device. <P>SOLUTION: This device is a port hole die in which a die mandrel and a die cap for extruding a hollow material of a metallic material are combined and has a plug which is freely rotatable taking the direction of extrusion as the center of the rotation at the front end in the extruding direction of the male head of the die mandrel. The plug is made into an approximately truncated conical shape which is expanded in the extruding direction in the outline, has a spiral projected line on the outer peripheral surface and is provided with a ring-like flow guide for generating twist in the metal flow just under a port hole in the die chamber. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method and apparatus for manufacturing a tube having a spiral groove on the inner surface by extrusion.

As a heat transfer tube used for a heat exchanger or the like, a tube provided with a fine spiral groove on the inner surface of the tube is employed in order to increase the heat transfer efficiency.
Various methods for forming a spiral groove have also been proposed. The diameter is reduced by a die immediately after extrusion, and the groove is formed on the inner surface of the tube by extruding from a grooved plug provided at the tip of the mandrel and the die. (See Patent Document 1), a method using a rotating wheel type extruder that drives and rotates a grooved mandrel from the outside to form a spiral groove (see Patent Document 2), and twists the porthole shape. A method of generating a swirling flow in a chamber and extruding it along a twisted groove of a mandrel (see Patent Document 3) is disclosed.
However, in the structure in which the diameter of the die is reduced immediately after the extrusion described in Patent Document 1, there is a possibility that the extrusion may become clogged due to cueing at the start of extrusion molding, and even if extrusion molding is possible, the die will be reduced. The resistance of the diameter portion was increased and the productivity was lowered.
The method of rotating the plug at the end of the mandrel described in Patent Document 2 by an external drive means can be applied to rotary wheel extrusion, but in the case of general direct extrusion, the extruder is placed on the drive shaft of the plug. Due to the presence of the stem, the plug could not be driven, making it difficult to apply.
In the method of extruding after the material described in Patent Document 3 is twisted largely, the outer periphery of the extruded tube is greatly rotated and pushed out so that the tip of the extruded tube is chucked and the puller leading in the extrusion direction is made to be rotatable. Although it is necessary, in general, heat exchange tubes are often extruded after being continuously extruded to ensure the convenience and productivity of the post-processing process. In order to make the devices compatible, extremely complicated facilities were required.

Japanese Patent Laid-Open No. 10-166085 JP-A-10-166034 Japanese Patent Laid-Open No. 10-166036

  The present invention has been made in the background of the above circumstances, and an object of the present invention is to provide a method of manufacturing a pipe having a spiral groove on the inner surface, which can be manufactured with an apparatus having a simple structure and has high productivity, and an apparatus therefor. And

In order to solve the above technical problem, the manufacturing apparatus of the inner surface spiral grooved pipe according to the present invention is a port hole die for a hollow material extrusion process of a metal material, which is a combination of a die mandrel and a die cap, At the front end in the extrusion direction of the male neck of the die mandrel, there is a plug that is rotatable about the extrusion direction as the rotation center. The plug has a generally truncated cone shape whose outer shape spreads in the extrusion direction and spirals on the outer peripheral surface. And a ring-shaped flow guide for twisting the metal flow is provided immediately below the port hole in the die chamber.
Thereby, a spiral groove can be formed in the inner surface of a pipe | tube only by providing the plug which has a helical protrusion at the front-end | tip of the mandrel of a general extrusion apparatus.
In addition, after extruding the metal material from between the die cap and the die mandrel to form an extruded tube, the extruded tube having an inner diameter formed by the die mandrel is pressed against the plug. A spiral can be formed on the inner surface without the outer surface being constrained.
In addition, by providing a flow guide in the die chamber to create a metal flow, rotation of the plug is promoted, and an internally spiral grooved tube having a spiral groove with a large twist angle can be formed.

  For example, the flow guide has step surfaces with different heights from the bottom of the chamber, and the step surfaces alternately have a number of high step surfaces and low step surfaces corresponding to the number of port holes. If the boundary step between the surface and the low step surface overlaps with the port hole, the metal diverted in the port hole flows to the step part of the flow guide directly under the port hole, resulting in a large flow difference and the die cap Since the extruded tube is extruded by rotating in the opposite direction or the same direction as the direction of rotation of the plug from between the die and the mandrel, it is possible to manufacture an internally spiral grooved tube having a spiral groove with a larger twist angle. Become.

  In addition, the height of the flow guide from the bottom of the chamber is divided according to the number of port holes, and the stepped surfaces of the spiral ridges of the plug become higher in the twist direction or in the direction opposite to the twist direction. If the stepped part of the stepped surface with different heights overlaps with the port hole, the flow of the flow guide can be changed to create a metal flow difference in the chamber and between the die cap and the die mandrel. Since the extruded tube is extruded by being rotated in the opposite direction or the same direction as the plug rotation direction, the rotational force generated by the spiral protrusion of the plug, and the rotational resistance generated by the plug being pressed in the extrusion direction, In this balance, it becomes possible to be in an optimum state, and it is possible to manufacture an internally spiral grooved tube having a spiral groove with a larger twist angle.

  Therefore, the manufacturing method of the inner surface spiral grooved tube according to the present invention is a porthole die combining a die mandrel and a die cap, with the extrusion direction being the rotation center at the front end of the male neck of the die mandrel. The plug has a generally frustoconical shape whose outer shape spreads in the extrusion direction, and has a spiral protrusion on the outer peripheral surface. The plug is extruded directly under the port hole in the die chamber. Using an extrusion die having a ring-shaped flow guide with a stepped portion in the direction, the metal material is extruded and the metal flow is twisted by the flow guide while being extruded from between the die mandrel and the die cap. The inner peripheral surface of the extruded tube is pressed by the protrusions on the plug surface, and a spiral groove is formed on the inner surface by rotating the plug.

  According to the present invention, when forming a spiral groove on the inner surface of a pipe using a plug having a plurality of spiral protrusions on the outer periphery, the spiral groove angle on the inner surface is large without requiring a complicated mold structure. It becomes possible to easily and stably manufacture the inner spiral groove tube.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing an embodiment of the present invention.
As shown in FIG. 1, a die cap 2 is combined with a die mandrel 1 to form a cross-sectional hole.
The die mandrel 1 and the die cap 2 are assembled to the die ring 8 together with the front backer 7 to constitute an extrusion die.
The billet 5 made of a metal material such as an aluminum alloy is inserted into the container 3 heated by the container heater 6 and pressed against the extrusion die by the stem 4 so that the extrusion tube 11 can be extruded from the cross-sectional hole of the extrusion die. ing.
2 is a cross-sectional view taken along line AA of FIG. 1, and FIG. 3 is a partially enlarged cross-sectional view of FIG. 1 mainly including a die mandrel 1 and a die cap 2.
As shown in FIG. 2, four port holes 1 </ b> P parallel to the extrusion direction are formed in the die mandrel 1.
As shown in FIG. 3, the male neck 1 a located at the center of the die mandrel 1 has a bearing 1 d that molds the inner surface of the extruded tube 11.
The die cap 2 has a bearing 2 b that forms the outer surface of the extruded tube 11.
The bearing 1d and the bearing 2b are substantially in the same position in the extrusion direction, and form a cross-sectional hole of the extrusion die.
A flow guide 31 is combined with the die cap 2 and fixed with a knock pin (not shown).
As shown in FIGS. 8 and 9, the flow guide 31 has a ring shape and is provided in the chamber bottom 2c immediately below the port hole 1p.
A shaft 1b is provided at the tip of the male neck 1a of the die mandrel 1, and a plug 9 is rotatably attached to the shaft 1b.
A threaded portion 1c is formed at the tip of the shaft 1b, and a nut 10 for retaining the plug 9 is attached.
4 shows the plug 9 alone, FIG. 4 (a) is a front view, and FIG. 4 (b) is a right side view.
The plug 9 has a plurality of spiral protrusions 9a on the outer periphery.
The protrusion 9a is formed by turning in the clockwise direction at a predetermined twist angle α with respect to the extrusion direction.
A recess 9b is similarly formed between the two adjacent ridges 9a so as to turn in the clockwise direction.
The twist angle α is an angle formed by the protrusion 9a with the extrusion axis Z when viewed from the front (direction perpendicular to the extrusion axis Z) as shown in FIG.
Note that the direction of rotation of the spiral is not limited to right rotation, but in this evaluation, the right rotation is used.
The plug 9 is formed in a substantially truncated cone shape whose diameter increases toward the front in the extrusion direction.
That is, the diameter gradually increases from the circumscribed circle 9h at the rear end of the plug 9 toward the circumscribed circle 9g at the front end, and in a front view as shown in FIG. It has become.
The shaft 1 b is inserted into the plug hole 9 c of the plug 9, and the plug 9 is assembled to the die mandrel 1.
As shown in FIG. 3, the diameter 9f of the circumscribed circle 9g at the front end, which is the maximum protrusion diameter of the plug 9, is larger than the outer diameter 1h of the bearing 1d of the die mandrel 1, and the inner diameter of the bearing 2b of the die cap 2 It is set smaller than 2c.
The diameter 9e of the circumscribed circle 9h at the rear end, which is the minimum protrusion diameter of the plug 9, is set smaller than the outer diameter 1h of the bearing 1d of the die mandrel 1.

As shown in FIG. 1, a billet 5 of a heated aluminum alloy is inserted into a container 3 heated by a container heater 6 and pressed against an extrusion die by a stem 4 so that the aluminum alloy is in a port hole 1p and a die chamber 2a. Then, the flow of the metal is guided by the flow guide 31, and the extruded tube 11 is extruded from between the bearing 1d and the bearing 2b.
The extruded tube 11 has a cross section as shown in FIG. 5, and the outer surface 11a of the extruded tube 11 has substantially the same outer diameter as the inner diameter 2c of the bearing 2b. The inner surface 11b of the extruded tube 11 has the outer diameter of the bearing 1d. It is substantially the same as 1h.
Since the extruded tube 11 is a smooth cylindrical pipe and is immediately after being pushed out from between the bearing 1d and the bearing 2b, the outer surface 11a and the inner surface 11b are not uneven.
Since the diameter 9e of the circumscribed circle 9h at the rear end of the plug 9 is smaller than the inner diameter 11c of the extruded tube 11, the extruded tube 11 immediately after being extruded from the extrusion mold does not come into contact with the protrusion 9a of the plug 9.
Thereafter, as the circumscribed circle of the protrusion 9a of the plug 9 expands toward the front in the extrusion direction, the inner surface 11b of the extruded tube 11 gradually approaches the protrusion 9a and eventually comes into contact with the protrusion 9a. It is pressed against the ridge 9a.
As a result, a spiral groove 12 c is formed in the inner diameter 11 c of the extruded tube 11.
The plug 9 rotates counterclockwise around the shaft 1b due to the resistance when the groove is formed in the inner diameter 11c of the extruded tube 11.

When the plug 9 is rotated counterclockwise, the spiral groove 12c formed in the inner diameter 11c of the extruded tube 11 is formed by turning in the clockwise direction at a predetermined twist angle β with respect to the extruded direction, and is an inner surface that is a spiral tube. A spiral grooved tube 12 is manufactured.
The inner spiral grooved tube 12 has a cross section as shown in FIG. 6, the outer surface 12a is smooth and has no irregularities, and a spiral groove 12c is formed on the inner surface 12b. The twist angle β is an angle that makes the cross-sectional view with the extrusion axis Z as shown in FIG.
The twist angle β is smaller than the twist angle α.
As described above, according to the method for manufacturing the inner surface spiral grooved tube 12 according to the present invention, the die 9 is simply provided with the plug 9 having the spiral protrusion 9a at the tip of the die mandrel 1 of a general extrusion apparatus. A spiral groove 12 c can be formed on the inner surface 11 b of the extruded tube 11 extruded from between the mandrel 1 and the die cap 2.
In addition, by providing a flow guide 31 in the die chamber 2a and creating a metal flow, rotation of the plug is promoted, and an inner spiral grooved tube having a spiral groove with a large twist angle can be formed.
Next, a specific example of the flow guide 31 for guiding the metal flow will be described.

The example of the flow guide 41 shown in FIG. 8 is an example in which the height from the bottom 2c of the die chamber 2a is divided into four so as to increase sequentially clockwise as viewed in the extrusion direction with Ha, Hb, Hc, Hd.
The reason for the division into four is that four ports are used in this embodiment.
An example of the specification is shown in Table 1 of FIG.
In this evaluation, three types of flow guides 41 are set, and the names of follow guides are FH6, FH9, and FH12 from the highest height of the steps.
Further, as shown in FIG. 8, a counterclockwise flow guide having a stepwise increase in the counterclockwise direction was manufactured in the same manner as the stepwise flow guide having the stepped surface height increased.
The flow guide 41 is installed in the die chamber 2a, the center of the step surface is aligned with the center of the hole of the port hole 1p, and is arranged A. The boundary step portion between the step surface and the step surface with respect to the hole of the port hole 1p Was arranged, that is, the one offset by 45 ° was designated as arrangement B.
FIG. 10 shows a diagram in which a clockwise four-step flow guide is installed in the arrangement A. FIG.
FIG. 11 is a diagram in which a counterclockwise four-step flow guide is installed in the arrangement A.
FIG. 12 shows a diagram in which a clockwise four-step flow guide is installed in the arrangement B.
FIG. 13 shows a diagram in which a counterclockwise four-stage flow guide is installed in the arrangement B.
Further, as a method for forming the step portion of the flow guide, the equally divided four-division flow guide 31 shown in FIG. 9 was also comparatively evaluated.
In the flow guide 31, the high step portion 31a was 12 mm, and the low portion 31b was 1.5 mm.
The flow guide 31 is installed in the die chamber 2a, and when viewed in the extrusion direction, the arrangement with the right side higher than the hole of the port hole 1p is set to the right height, and the arrangement with the left side higher than the hole of the port hole 1p is set to the left height.
FIG. 14 shows a diagram in which an equally divided four-part flow guide is installed at the right height.
FIG. 15 shows a diagram in which an equal four-divided flow guide is installed at the left height.
The production conditions were extrusion molding at a billet temperature of 400 ° C. and a ram speed of 1 mm / second.
As a preliminary experiment, as shown in the table of FIG. 17, a flow guide with a maximum height of 9 mmFH9, clockwise and counterclockwise in offset arrangement B, clockwise and counterclockwise in arrangement A, and right and left height in equal four divisions. The conventional technology without FG (FG-less) was compared, and the plug angle at this time was α = 14 °, and the twist angle β of the inner spiral groove was evaluated.
The graph is shown in FIG.
The arrangement B of the four-stage flow guide and equally divided into four parts each had a larger β value than the FG-less, and the effect of promoting the twist of the inner spiral groove was recognized.
In the four-stage flow guide having the arrangement A, the inner groove was not spiral because the plug did not rotate.
Therefore, it was found that when the plug rotates, if the flow guide is placed in the die chamber, the inner spiral groove is closer to the plug angle than without the flow guide.
Next, as shown in Table 2 of FIG. 19, using plugs having a plug angle α = 14 °, the height of the flow guide, the difference in the inner diameter of the extruded tube, and the like were compared and evaluated.
A graph is shown in FIG.
No. 1, 2 and 3 are four-stage flow guides that are raised clockwise with respect to the extrusion direction, set in the arrangement B (offset), and investigated the effect of the height of the step surface.
FH6 and FH9 had a larger value of the inner spiral groove twist angle β than the conventional FG-less, but FH12 had a smaller β value because the plug did not rotate.
No. 4, 5, and 6 are investigations of the effect of the height of the step surface when a four-step flow guide that is raised counterclockwise is set in the arrangement B.
The higher the level difference, the more stable the β from the first half to the second half of extrusion.
In the arrangement B, the metal divided into four at the hole of the port hole 1p flows to the stepped portion of the flow guide 41 immediately below the port hole, and the metal at the outlet of the shape member due to the flow difference at the stepped portion. It is presumed that the twist angle β can be increased by causing the flow 61 to be twisted.
Also, as the height of the flow guide increases, the twist angle increases because the flow guide height increases, so the frictional force on the metal increases and the flow difference of the metal increases. It is estimated from.
When comparing the clockwise and counterclockwise steps, the metal flow in the clockwise direction is the direction of the plug rotation (direction toward the plug crest) as schematically shown by the arrow in FIG. On the other hand, in the counterclockwise direction, it is considered that the metal flows in the direction opposite to the rotation direction of the plug (the direction along the peak of the plug) as shown in FIG.
As for the step direction of the flow guide, the twist angle is large in the counterclockwise direction, and the twist angle is stable from the first half to the second half.
From these, it became clear that the profile can be twisted by the flow difference generated at the step portion of the flow guide.
Table 3 in FIG. 20 shows the measurement results of the twist angle β with a plug angle of 17.5 °.
Compared with the conventional (FG-less) that does not use a flow guide, the four-stage flow guide that increases counterclockwise has a large twist angle β and a stable twist angle from the first half to the second half.
In addition, No. 24 did not turn the plug.

Next, a comparative evaluation was made in detail using an equal four-divided flow guide 31 used in the preliminary experiment.
In the flow guide 31, the high step portion 31a was 12 mm, and the low portion 31b was 1.5 mm.
The production conditions were extrusion molding at a billet temperature of 400 ° C. and a ram speed of 1 mm / second.
Table 2 in FIG. 19 shows the results of the twist angle of the plug angle of 14 ° and the uniform 4-split flow guide. 14-21. The graph is shown in FIG.
When the uniform four-part flow guide is used, the twist angle β is larger than when the conventional flow guide is not used (FGless), and is stable even in the latter half of the extrusion.
The flow of metal is shown in FIGS.
The right height is the direction along the plug ridge, and the left height is the metal flow in the direction toward the plug hill.
Table 3 in FIG. 20 shows No. 25 and No. 26 the results of the twist angle of the plug angle 17.5 ° equally divided into four flow guides.
The graph is shown in FIG.
Compared to the conventional case in which no flow guide is used, by using an equally divided four-part flow guide, the twist angle β is large and the twist angle from the first half to the second half is also stable.

  In each of the above-described embodiments, the example in which the number of the spiral grooves 12c of the inner surface spiral grooved tube 12 (that is, the number of the protrusions 9a of the plug 9) is 16 is shown. When applied to a tube for a heat exchanger in particular, the number of spiral grooves can be increased (for example, about 50 spiral grooves in a tube having an outer diameter of φ6 mm).

It is sectional drawing which showed one Embodiment of this invention. It is an AA cross section of FIG. It is a partial expanded sectional view of FIG. It is a figure which shows the plug 9 single-piece | unit, FIG. 4 (a) is a front view, FIG.4 (b) is a right view. 2 is a cross-sectional view of an extruded tube 11. FIG. It is sectional drawing of the pipe 12 with an internal spiral groove. 3 is a cross section of the inner spiral grooved tube 12. It is a figure which shows a 4-step flow guide. It is a figure which shows an equal 4 division | segmentation flow guide. It is the figure which installed the clockwise flow guide with four steps in arrangement A. It is the figure which installed the flow guide with four steps of counterclockwise in arrangement | positioning A. FIG. It is the figure which installed the clockwise flow guide with four steps in arrangement B. It is the figure which installed the flow guide with four steps of the counterclockwise in arrangement B. It is the figure which installed the equal 4 division | segmentation flow guide in the right height. It is the figure which installed the equal 4 division flow guide in the left height. The step specifications of the stepped flow guide are shown. The flow guide used in the preliminary experiment and the measurement result of the twist angle β are shown. A graph of the twist angle β of the preliminary experiment when α = 14 ° is shown. When the plug angle α is 14 °, the measurement result of the twist angle (β) of the inner spiral groove of the extruded tube is shown. When the plug angle α = 17.5 °, the measurement result of the torsion angle (β) of the inner spiral groove of the extruded tube is shown. A graph of the twist angle of β when α = 14 ° is shown. A graph of the twist angle of β when α = 17.5 ° is shown. The graph of the twist angle of β of the equally divided flow guide and the four-step flow guide when α = 14 ° is shown.

Explanation of symbols

1 Die mandrel 1a Male neck 1b Shaft 1h Mandrel outer diameter 1p Port hole 2 Die cap 2a Die chamber 2c Chamber bottom 3 Container 4 Stem 5 Billet (metal material)
7 Backer 8 Die ring 9 Plug 9a Projection 9b Recess 9d Tapered portion 9e circumscribed circle 9f at the rear end of the plug 9 circumscribed circle at the front end of the plug 9 (maximum circumscribed circle)
9g Diameter 9h of circumscribed circle 9f Diameter 9k of circumscribed circle 9e Plug rotation direction 11 Extruded tube 11a Outer surface 11b of extruded tube 11 Inner surface 12 of extruded tube 11 Inner surface spiral grooved tube 12a Outer surface 12b of inner surface spiral grooved tube 12 Inner surface spiral Inner surface 12c of grooved tube 12 Spiral grooves 31, 31a, 31b Equally divided into four divided flow guides 41, 41a, 41b, 41c, 41d Flow guide with four steps 61 Flow direction of metal

Claims (6)

For hollow material extrusion of metal materials,
It is a port hole die that combines a die mandrel and a die cap, and has a plug that is rotatable around the extrusion direction as a rotation center at the front end of the male neck of the die mandrel.
The plug has a generally truncated cone shape whose outer shape spreads in the extrusion direction and has a spiral protrusion on the outer peripheral surface,
An apparatus for manufacturing an internally spiral grooved tube, characterized in that a ring-shaped flow guide is provided immediately below a port hole in a die chamber to cause a twist in a metal flow.   The flow guide has step surfaces with different heights from the bottom of the chamber, and the step surfaces alternately have high step surfaces and low step surfaces corresponding to the number of port holes. 2. An apparatus for manufacturing an internally spiral grooved tube according to claim 1, wherein the stepped portion between the low step surface and the port hole overlaps with the port hole. The height of the flow guide from the bottom of the chamber is divided according to the number of holes in the port hole, and the stepped surface of the spiral ridge of the plug is gradually increased in the twist direction or in the direction opposite to the twist direction.
The apparatus for manufacturing an internally spiral grooved tube according to claim 1, wherein the boundary stepped portions of stepped surfaces having different heights are arranged so as to overlap with the port holes. It is a port hole die that combines a die mandrel and a die cap, and has a plug that is rotatable around the extrusion direction as a rotation center at the front end of the male neck of the die mandrel.
The plug has a generally truncated cone shape whose outer shape spreads in the extrusion direction and has a spiral protrusion on the outer peripheral surface,
Using an extrusion die having a ring-shaped flow guide in which a step portion in the extrusion direction is formed immediately below the port hole in the die chamber, while extruding a metal material and causing a twist in the metal flow with the flow guide, An inner surface spiral characterized in that an inner peripheral surface of an extruded tube extruded from between a die mandrel and a die cap is pressed by a protrusion on the plug surface, and a spiral groove is formed on the inner surface by rotating the plug. A method of manufacturing a grooved tube.   The flow guide has step surfaces with different heights from the bottom of the chamber, and the step surfaces alternately have high step surfaces and low step surfaces corresponding to the number of port holes. 5. The method of manufacturing an internally spiral grooved tube according to claim 4, wherein an extrusion die arranged so that a boundary step portion with a low step surface overlaps with a port hole is used. The height of the flow guide from the bottom of the chamber is divided according to the number of holes in the port hole, and the stepped surface of the spiral ridge of the plug is gradually increased in the twist direction or in the direction opposite to the twist direction.
5. The method for producing an internally spiral grooved tube according to claim 4, wherein an extrusion die is used so that boundary step portions of step surfaces having different heights overlap with port holes.

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