JP4967987B2 - Manufacturing method of heat-resistant tube with high pressure resistant inner groove - Google Patents

Description

  The present invention relates to a method for manufacturing a heat-resistant tube with a high pressure resistant inner surface groove that can manufacture a heat-transfer tube with an inner surface groove that is thick and has a high twist angle of the inner surface groove.

  An internally grooved heat transfer tube used for a CO2 water heater or the like has a plurality of helical inner grooves on the inner surface.

  Conventionally, the manufacturing method of the inner surface grooved heat transfer tube is to prepare a dough tube having a diameter larger than the outer diameter of the tube to be obtained, and arrange a floating plug and a grooved plug inside the dough tube, while on the outside of the dough tube. Is arranged with a drawing die and pressing means along the drawing direction of the dough tube, and pulling out the dough tube at a constant speed and pressing it so as to form an inner surface groove and reduce the tube (also referred to as a reduced diameter). It has become.

  Specifically, as shown in FIG. 5, the conventional manufacturing apparatus 51 sequentially arranges the leading drawing die 3, the pressing means 4, the intermediate drawing die 5, and the rising drawing die 7 along the drawing direction of the dough tube 2. Do it.

  Each of the drawing dies 3, 5, and 7 has an inlet having a large inner diameter and an outlet having a small inner diameter, and a tapered cavity or a trumpet cavity for contracting the dough pipe is formed between the inlet and outlet. The leading drawing die 3, the intermediate drawing die 5, and the rising drawing die 7 are arranged so that the inner diameters of the outlets are different and the inner diameters of the outlets are sequentially reduced.

  The pressing means 4 has a plurality of balls or rolls for pressing the outer periphery of the dough tube 2.

  The floating plug 8 has a tapered cone portion that opposes the tapered cavity of the leading drawing die 3, and the maximum outer diameter of the tapered cone portion is larger than the outlet of the leading drawing die 3. The grooved plug 9 is formed by forming a spiral groove that is a male and female reverse type of the inner surface groove to be formed on the dough tube 2 around the cylinder.

  The floating plug 8 and the grooved plug 9 are coaxially connected by a tie rod 10 having a diameter smaller than these. A connecting body in which the floating plug 8 and the grooved plug 9 are connected by a tie lot 10 is arranged in the dough tube 2. This coupling body is rotatable around the axis of the dough tube 2 in the dough tube 2. As will be described later, since the floating plug 8 is locked in the dough tube 2 in the leading drawing die 3, the length of the tie lot 10 or leading drawing is performed so that the pressing means 4 comes to the position of the grooved plug 9 at that time. Adjust the distance between the die pressing means.

  The dough tube 2 is hollow and has a smooth inner surface (no grooves), and a material such as a copper tube having excellent heat conductivity is used.

  In this manufacturing apparatus 51, when the dough tube 2 is pulled out in the drawing direction indicated by an arrow in the drawing in a state where the connecting body in which the floating plug 8 and the grooved plug 9 are connected by the tylot 10 is arranged in the dough tube 2, The dough tube 2 is contracted by the drawing die 3. At this time, since the tapered cone portion has a larger diameter than the outlet of the leading drawing die 3, the tapered cone portion is locked at a position in the leading drawing die 3, and the position of the floating plug 8 in the drawing direction is fixed. .

  By fixing the position of the floating plug 8 in the pulling direction, the grooved plug 9 is also fixed in the pulling direction. At the position of the grooved plug 9, the pressing means 4 revolves around the dough tube 2 and presses the dough tube radially inward. By this pressing force, the groove of the grooved plug 9 is transferred to the inner surface of the dough tube 2 to form an inner surface groove (or fin).

  Thereafter, the dough pipe 2 is gradually contracted by sequentially passing through the intermediate drawing die 5 and the upward drawing die 7.

  Through the above steps, the internally grooved heat transfer tube is manufactured.

  Here, with reference to FIG. 6, the specifications of the internally grooved heat transfer tube will be described together with the structure of the internally grooved heat transfer tube.

  As shown in FIG. 6A, the inner surface grooved heat transfer tube 61 has a plurality of spiral inner surface grooves 62 on the inner surface. The inner surface groove 62 refers to a so-called valley portion where the diameter of the hollow portion is large. On the other hand, the thick mountain portion of the heat transfer tube main body (meat portion) 63 is called a fin 64. FIG. 6A is a simplified diagram, in which the inner groove 62 is drawn linearly. An angle β formed by the inner surface groove 62 with respect to the tube axis S is referred to as a twist angle.

  The radial distance from the bottom of the inner surface groove 62 to the top of the fin 64 is referred to as the groove depth H, and the distance between the side surfaces of the adjacent fins 64 is referred to as the width W of the inner surface groove 62.

JP-A-5-007920 JP-A-5-329529 JP-A-6-015345 "Plastic processing technology series 11 rotary processing" pages 218-222

  In order to increase the pressure resistance of the internally grooved heat transfer tube, it is preferable to thicken the internally grooved heat transfer tube.

  In the conventional method for manufacturing an internally grooved heat transfer tube, when a thick internal grooved heat transfer tube is manufactured, a thick fabric tube is used as the fabric tube. Alternatively, there is also a method of increasing the thickness by reducing the diameter of the internally grooved heat transfer tube once manufactured by an arc die.

  However, in the conventional manufacturing apparatus shown in FIG. 5, when an attempt is made to manufacture a thick inner surface grooved heat transfer tube using the thick dough tube 2, the pressing force from the pressing means 4 is applied to the inner surface of the dough tube 2. It is difficult to form a deep inner groove, and an inner groove with a high twist angle cannot be formed.

  On the other hand, in the method of reducing the diameter of the internally grooved heat transfer tube with an arc die and increasing the thickness, the amount of increase in the thickness is small, so the effect of increasing the pressure resistance is extremely low. Moreover, since the dough tube extends greatly in the longitudinal direction, the twist angle of the inner surface groove decreases, and the heat transfer performance of the inner surface grooved heat transfer tube is deteriorated.

  Then, the objective of this invention is providing the manufacturing method of the heat-resistant tube | pipe with a high pressure | voltage resistant inner surface groove | channel which can manufacture the inner surface grooved heat exchanger tube which solves the said subject and the twist angle of an inner surface groove | channel is high.

  In order to achieve the above object, according to the present invention, a floating plug and a grooved plug connected to the floating plug are arranged inside a dough pipe having a diameter larger than the outer diameter of the pipe to be obtained. A drawing die, a pressing means and a rotary agitator are arranged in this order along the drawing direction of the dough tube, and the dough tube is pulled out, whereby the dough tube is contracted with the drawing die and the floating tube is placed in the contracted dough tube. The plug is locked, the dough pipe is pressed by the pressing means at the position of the grooved plug, the groove is transferred to the inner surface of the dough pipe, and the dough pipe is increased in thickness and reduced by the rotary agitator. .

  An intermediate drawing die may be arranged between the pressing means and the rotary agitator, and the dough pipe exiting the pressing means may be contracted by the intermediate drawing die and then passed through the rotary agitator.

  A pulling die may be arranged so as to rise in the pulling direction from the rotary agitator, and the dough pipe exiting the rotary agitator may be lifted and contracted by the pulling die.

  The present invention exhibits the following excellent effects.

  (1) A thick inner-surface grooved heat transfer tube can be manufactured.

  (2) An internally grooved heat transfer tube having a high twist angle of the internal groove can be manufactured.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, a manufacturing apparatus 1 for carrying out the manufacturing method of a heat-resistant tube with a high pressure resistant inner groove according to the present invention includes a leading drawing die 3, a pressing means 4, an intermediate drawing die along the drawing direction of the dough tube 2. 5, a rotary agitator 6 and an upward pulling die 7 are arranged in this order.

  The drawing dies 3, 5, and 7 and the pressing means 4 are the same as the conventional one shown in FIG. The floating plug 8, the grooved plug 9, and the tie lot 10 are also the same as the conventional one shown in FIG. The dough tube 2 is also thin with the same thickness as the conventional one shown in FIG.

  The rotary agitator 6 contracts the dough tube by alternately pushing a plurality of divided dies formed in the circumferential direction with a plurality of rollers arranged around the dies. The rotary agent 6 is a conventionally known one, and for example, the one disclosed in Non-Patent Document 1 can be used.

  According to the manufacturing apparatus 1 of FIG. 1, the floating plug 8 and the grooved plug 9 connected to the floating plug 8 are arranged inside the dough pipe 2 having a diameter larger than the outer diameter of the pipe to be obtained. A leading drawing die 3, a pressing means 4, an intermediate drawing die 5, a rotary agitator 6, and a rising drawing die 7 are arranged in this order along the drawing direction of the dough tube 2.

  By pulling out the dough tube 2, the dough tube 2 is contracted with the leading drawing die 3 and the floating plug 8 is locked in the contracted dough tube 2. In this state, a groove transfer step in which the dough pipe 2 is pressed in the radial direction by the pressing means 4 at the position of the grooved plug 9 to transfer the groove to the inner surface of the dough tube 2, and an inner groove is formed by this groove transfer step. The dough tube 2 is passed through the intermediate drawing die 5 and the upward drawing die 7 to be contracted (empty drawing) to a predetermined external dimension, and the intermediate drawing die 5 and the upward drawing die 7 in the contracting step And a thickening / shrinking step (swaging) of increasing the thickness of the dough tube 2 with the rotary agitator 6 between the two. Thereby, a thick inner-surface grooved heat transfer tube, that is, a high pressure resistant inner-surface grooved heat transfer tube is manufactured.

  Here, the thickening contraction means increasing the thickness while reducing the outer diameter. When attention is paid to the position of the arrow A in FIG. 1, the outer diameter of the dough tube 2 at the outlet of the rotary agitator 6 is smaller than the outer diameter of the dough tube 2 at the inlet of the rotary agitator 6. Further, the thickness of the dough tube 2 at the outlet of the rotary agitator 6 is thicker than the thickness of the dough tube 2 at the entrance of the rotary agitator 6.

  In the rotary agitator described in Non-Patent Document 1, when the cam surface formed on the top surface of the backer is in rolling contact with the roller, the die moves forward in the direction of the workpiece, and the workpiece is removed. It compresses in the radial direction, and feeds the work piece in the axial direction little by little while the pressure applied by the die is released.

  The inventor of the present invention realized a wall-thickening contraction tube by setting the conditions so that the material flow at the time of compressive deformation does not occur toward the material inlet in this rotary aisle.

  Next, the effect of the present invention will be described.

  2 and 3, a high pressure internal grooved heat transfer tube having an outer diameter of φ7 mm and a wall thickness of 0.31 mm is used as a sample, and this sample is scanned by the prior art emptying and the manufacturing method of the present invention. The graph showing the change of an inner surface shape when shrinking | reducing pipe | tube or a wall-thickening shrinkage | contraction by aging is shown. FIG. 2 is a graph in which the horizontal axis indicates the outer diameter of the internally grooved heat transfer tube or the high pressure resistant internal grooved heat transfer tube, and the vertical axis indicates the cross-sectional dimensions (wall thickness and groove depth). Represents the change in cross-sectional dimensions during tube expansion. FIG. 3 is a graph in which the horizontal axis represents the outer diameter of the internally grooved heat transfer tube or the high pressure resistant internal grooved heat transfer tube, and the vertical axis represents the twist angle of the inner surface groove. Represents the change in the twist angle.

  In FIG. 2, ● and ▲ indicate the results of the manufacturing method of the present invention, and ◯ and Δ indicate the results of the conventional manufacturing method. According to this, it can be seen that when the thickness increase and contraction is performed by the manufacturing method of the present invention, the thickness increases.

  In FIG. 3, ● represents the result of the production method of the present invention, and ○ represents the result of the conventional production method. According to this, it is understood that the degree of decrease in the twist angle becomes small when the wall thickness expansion and contraction is performed by the manufacturing method of the present invention.

  FIG. 4 shows a cross-sectional photograph of a conventional internally grooved heat transfer tube or a high pressure resistant internally grooved heat transfer tube according to the manufacturing method of the present invention, and FIG. 7 shows a copy of these photographs. That is, FIGS. 4A and 7A show cross sections of the internally grooved heat transfer tube before processing, and correspond to ●, ○, ▲, and Δ of 7 mm in outer diameter in FIGS. 4 (b), FIG. 7 (b), FIG. 4 (c), and FIG. 7 (c) are high-pressure-resistant inner surface grooves that are manufactured by performing the contraction process using the rotary agitator 6 by the manufacturing method of the present invention. The cross section of an attached heat transfer tube is shown, and corresponds to ● and ▲ in FIGS. 4 (d), FIG. 7 (d), FIG. 4 (e), and FIG. 7 (e) show an internally grooved transmission manufactured by a conventional manufacturing method without performing the contraction tube process using the rotary agitator 6. The cross section of the heat tube is shown and corresponds to the circles 6 and 5 in FIGS.

  As can be seen from FIGS. 4 and 7, the heat-resistant tube with a high pressure resistant inner groove manufactured according to the present invention is thicker than the conventional one.

  As described above, according to the present invention, the dough pipe formed by transferring the inner surface groove is increased in thickness by the rotary agitator, so that the thick inner surface groove is formed using the thin dough pipe. Attached heat transfer tubes can be manufactured. Thus, in the present invention, since the thin dough tube is used, the transfer of the groove from the grooved plug becomes easy, and the dough tube does not extend in the longitudinal direction in the increased thickness reduced tube, so that the inner surface groove An internally grooved heat transfer tube having a high twist angle can be manufactured.

  In the manufacturing apparatus of FIG. 1, an intermediate drawing die and a rising drawing die are used, but these drawing dies are appropriately omitted depending on the difference between the outer diameter of the tube to be obtained and the outer diameter of the original fabric tube. Can be increased.

It is a side view which shows the manufacturing apparatus which enforces the manufacturing method of the heat-resistant tube | pipe with a high pressure | voltage resistant inside groove | channel of this invention. It is a graph showing the change of the cross-sectional dimension at the time of a contraction pipe or a thickness expansion contraction. It is a graph showing the change of the twist angle at the time of a contraction pipe or an increase in thickness contraction. FIG. 4A is a cross-sectional view of a conventional internally grooved heat transfer tube or a high pressure resistant internal grooved heat transfer tube according to the manufacturing method of the present invention. FIG. 4A is a cross-sectional view of an internally grooved heat transfer tube that is not contracted, and FIG. 4 (c) is a cross section of a heat resistant tube with a high pressure resistant inner surface groove processed according to the present invention, and FIGS. 4 (d) and 4 (e) are cross sections of an internally grooved heat transfer tube processed according to the prior art. Show. It is a side view which shows the manufacturing apparatus of the conventional inner surface grooved heat exchanger tube. It is a figure which shows the item of an internally grooved heat exchanger tube, (a) is a sectional side view, (b) is a cross-sectional view, (c) is a partial cross-sectional view. FIGS. 7A to 7E are copy diagrams of FIGS. 4A to 4E.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Dough pipe 3 Leading drawing die 4 Pressing means 5 Intermediate drawing die 6 Rotating agent 7 Lifting drawing die 8 Floating plug 9 Grooved plug 10 Tylot

Claims (3)

  A floating plug and a grooved plug connected to the floating plug are arranged inside the dough pipe having a diameter larger than the outer diameter of the pipe to be obtained, and a drawing die is formed on the outside of the dough pipe along the drawing direction of the dough pipe. By sequentially arranging the pressing means and the rotary agitator and pulling out the dough pipe, the dough pipe is contracted with the drawing die, and the floating plug is locked in the contracted dough pipe, and the grooved plug The dough pipe is pressed at the position by the pressing means, the groove is transferred to the inner surface of the dough pipe, and the dough pipe is increased in thickness and contracted by the rotary adjuster. Method.   2. An intermediate drawing die is arranged between the pressing means and the rotary agitator, and the dough pipe exiting the pressing means is contracted by the intermediate drawing die and then passed through the rotary agitator. A manufacturing method of the heat-resistant tube with a high pressure-resistant inner surface groove according to 1.   3. A high pressure-resistant inner surface groove according to claim 1 or 2, wherein a drawing die is arranged in a drawing direction from said rotary agitator, and a dough pipe coming out of said rotary agitator is raised and contracted by a drawing die. Manufacturing method of heat transfer tube.

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