JP2005103603A - Apparatus and method for manufacturing pipe with grooved inner surface - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing a pipe with a grooved inner surface wherein deformation and rupture of a material pipe due to change of a rolling load are prevented, and also to provide a manufacturing method of the pipe with a grooved inner surface by using the manufacturing method. <P>SOLUTION: Lubricating oil 20 excellent in a lubricity is fed to an outer surface of the material pipe 1 from a nozzle 22. The material pipe 1 is diametrically reduced with a holding die 3 and a holding plug 2, while the lubricating oil 20 is removed from an outer surface of the material pipe 1. Next, lubricating oil 21 having higher cooling performance than the lubricating oil 20 is fed to the outer surface of the material pipe 1 from a nozzle 23. In a rolling section 7a, a groove is formed in an inner surface of the material pipe 1, and the material pipe 1 is diametrically reduced with a sizing die 8a, while the lubricating oil 21 is removed from the outer surface of the material pipe 1. Next, the lubricating oil 21 is fed to the outer surface of the material pipe 1 from a nozzle 23. In a rolling section 7b, a groove is formed in the inner surface of the material pipe 1, and the material pipe 1 is diametrically reduced with a sizing die 8b, while the lubricating oil 21 is removed from the outer surface of the material pipe 1. The pipe 19 with the grooved inner surface is manufactured thereby. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a seamless inner grooved tube manufacturing apparatus suitable as a heat transfer tube incorporated in a heat exchanger used in a room air conditioner, a packaged air conditioner, a vending machine or the like, and an inner grooved tube manufacturing method using the apparatus. In particular, the present invention relates to an apparatus and a method for manufacturing an internally grooved tube using a grooved plug and a rolling roll.

  The internally grooved tube is used as a heat transfer tube incorporated in an air-cooled heat exchanger used in an air conditioner or the like. There are two types of internally grooved pipes: seamless internally grooved pipes manufactured by rolling and welded internally grooved pipes manufactured by high frequency induction welding or the like. A welded inner surface grooved tube is formed by once forming a molten ingot into a plate material, subjecting the plate material to groove processing by a groove roll, and then rolling the plate material into an arc shape by roll forming, and then performing high frequency induction welding or TIG (Tungsten Inert Gas) manufactured by forming into a tube by welding. On the other hand, a seamless inner surface grooved tube is manufactured by directly forming a tube from a molten ingot and subjecting the tube to groove processing. For this reason, the seamless inner surface grooved tube requires fewer processes than the welded inner surface grooved tube and is superior to the welded inner surface grooved tube in productivity. In addition, in manufacturing a welded inner surface grooved tube, increasing the processing speed to improve productivity decreases the stability of the welding quality and causes a high current to flow through the heating coil. Life is shortened. In addition, the power consumption increases and the manufacturing cost increases.

  There are two methods for producing a seamless internally grooved tube: a ball rolling method and a roll machining method. First, a method for producing an internally grooved tube by ball rolling (hereinafter referred to as a ball rolling method) will be described. As the material, a raw tube made of an annealed material (O material) tempered by bright annealing or annealing by an induction heater is used. A grooved plug having a groove formed on the outer surface is inserted into the element tube, and a rolling ball that rotates in a planetary contact with the outer surface of the element tube is disposed at a position corresponding to the grooved plug. The planetary rotation of the rolling ball is performed by a magnetic levitation high-speed motor. Then, the rolled ball is pressed against the grooved plug by the rolling ball, and the grooved plug rotates around the tube axis by pulling out the raw tube, and the whole inner surface of the raw tube is The groove of the grooved plug is transferred to form a groove.

  However, the above-mentioned ball rolling method has the following problems. First, in the ball rolling method, it is necessary to use a magnetic levitation type high-speed motor to rotate the rolled ball at high speed. Since this magnetic levitation type high-speed motor is an extremely expensive device, there is a problem that the equipment cost is high.

  In the ball rolling method, it is necessary to increase the drawing speed of the pipe in order to improve the productivity of the seamless inner grooved pipe and reduce the manufacturing cost. On the other hand, in the ball rolling method, one of the factors affecting the groove formability of the inner surface of the tube is the processing pitch (the length of the raw tube that advances while one ball revolves once). In order to increase the drawing speed while maintaining the groove formability by setting this processing pitch to the same level as before, it is necessary to increase the revolution speed of the rolled ball. However, in a normal magnetic levitation type high-speed motor, the upper limit value of the rotational speed is about 30,000 rpm. For this reason, when the processing pitch of the pipe is 2 mm per rotation, the upper limit value of the drawing speed is about 60 m / min. Even in the current highest speed magnetically levitated high-speed motor, the rotational speed is limited to about 45,000 rpm, and therefore the extraction speed is limited to about 90 m / min. For this reason, in the ball rolling method, the drawing speed of the tube cannot be made very fast, and there is a limit to improving the productivity.

  Furthermore, in the ball rolling method, it is necessary to use an annealed material (O material) as a raw tube. This is because the ball rolling method deforms the pipe in the radial direction by the rolling ball that revolves. Therefore, if the pipe is not made of a soft material such as an annealed material, the pipe is sufficiently deformed. This is because the groove cannot be formed. For this reason, when a seamless inner grooved tube is manufactured by the ball rolling method, it is necessary to configure the base tube with an annealing material before performing ball rolling, which increases the manufacturing cost. When using a welded pipe, grooves can be formed even with a material that has not been annealed (H material), but it is easy to cause defects in the groove roll, which in turn increases costs. And it is preferable to comprise an element pipe with an annealing material.

  As described above, the manufacture of seamless inner surface grooved pipes by the ball rolling method can reduce the manufacturing cost as compared with the manufacture of welded inner surface grooved pipes, but it is necessary to install a magnetically levitated high-speed motor in the manufacturing equipment. In addition, it is difficult to increase the drawing speed of the tube, and there is a limit to the reduction of the manufacturing cost.

  Furthermore, in the ball rolling method, since the tube is pulled out while the material of the tube flows into the groove carved on the outer surface of the grooved plug, the grooved plug rotates as the tube is pulled out. This rotation causes the relative movement of the grooved plug relative to the tube to be lubricated. However, when the lead angle of the groove of the grooved plug, that is, the angle formed by the straight line parallel to the axial direction on the side surface of the grooved plug and the direction in which the groove extends is 0 ° (parallel to the tube drawing direction), the grooved The plug stops rotating and the tube breaks. For this reason, in the ball rolling method, it is difficult to form a groove parallel to the tube axis direction on the tube inner surface.

  Furthermore, even if a plurality of grooves having different lead angles are formed on the outer surface of the grooved plug, the grooved plug cannot be rotated. For this reason, a cross groove cannot be formed on the inner surface of the pipe by the ball rolling method. Furthermore, when grooves having the same lead angle but different pitches are formed on the outer surface of the grooved plug, the grooved plug can be rotated as the tube is pulled out. However, when the rolling ball revolves, the material of the tube moves in the circumferential direction along with the revolution and flows into the groove of the grooved plug to form a groove on the inner surface of the tube. When the groove moves from the dense area to the sparse area, the escape material for the tube material disappears. As a result, the shape of the groove formed on the inner surface of the tube becomes unstable, or the tube is broken due to fluctuations in the drawing load.

  Furthermore, it is possible in principle to form cross grooves and grooves with different pitches on the inner surface of the pipe by performing the rolling process twice. In practice, however, the grooved plug is used in the second rolling process. The load applied to the surface becomes too large, and the grooved plug is likely to be lost. For this reason, it is extremely difficult in practice to form cross grooves or grooves having different pitches on the inner surface of the pipe by two rolling processes.

  Furthermore, in the ball rolling method, the inner surface of the tube is divided into a plurality of regions in the tube circumferential direction, and different types of grooves are formed in each region, or grooves are formed only in some regions, and the remaining regions are formed. It is impossible not to form a groove. Thus, the ball rolling method has a problem that only a simple spiral groove having a constant lead angle and pitch can be formed on the inner surface of the tube, and the degree of freedom of the groove pattern that can be formed on the inner surface of the tube is extremely small.

  As means for solving these problems, there is a method for producing a seamless internally grooved tube by roll processing (see, for example, Patent Documents 1 to 3). A method for producing a seamless internally grooved tube by roll processing (hereinafter referred to as roll rolling method) will be described below.

  FIG. 3 is a cross-sectional view showing a seamless inner grooved heat transfer tube manufacturing apparatus and manufacturing method by a conventional roll rolling method, and FIG. 4 is an enlarged cross-sectional view showing a rolling part of the manufacturing apparatus shown in FIG. FIG. 5 is a sectional view taken along line AA shown in FIG. As shown in FIG. 3, a holding plug 2 is inserted into a base tube 1 made of copper or a copper alloy (hereinafter collectively referred to as copper). The shape of the holding plug 2 is such that the outer diameter on the tube supply side (upstream side) is slightly smaller than the inner diameter of the raw tube 1, and the outer diameter on the tube extraction side (downstream in the tube extraction direction) is smaller than the outer diameter on the tube supply side. It has become. A holding die 3 for reducing the diameter of the pipe 1 together with the holding plug 2 is disposed on the outer surface of the pipe 1 at a position aligned with the holding plug 2. A grooved plug 15 is connected to the holding plug 2 via a plug shaft 4. A groove having a shape to be formed on the inner peripheral surface of the raw tube 1 is processed on the outer peripheral surface of the grooved plug 15. The grooved plug 15 can freely rotate about the plug shaft 4 as an axis.

  Then, a pair of rolling rolls 6 are disposed so as to be in rolling contact with the outer surface of the raw tube 1 at a position aligned with the grooved plug 15 on the outer side of the raw tube 1. Each rolling roll 6 can rotate, and the direction of the rotation axis thereof is orthogonal to the tube axis direction of the raw tube 1. The grooved plug 15 and the rolling roll 6 constitute a rolling part 17. In addition, a sizing die 8 is provided on the downstream side of the rolling portion 17 in the tube drawing direction to reduce the outer diameter of the raw tube 1 having a groove formed on the inner surface to a predetermined size.

  As shown in FIG. 4, the rotation axis of the rolling roll 6 is located near the longitudinal center of the grooved plug 15 in the tube drawing direction. And as shown in FIG. 5, the shape of the rolling roll 6 is a drum shape in which the diameter of a roll center part is smaller than the diameter of a roll both ends, In the cross section containing the rotating shaft of this rolling roll 6, the shape of a side edge Is substantially matched to the outer surface shape of the raw tube 1. That is, the curvature radius of the side surface of the rolling roll 6 is substantially equal to the curvature radius of the outer surface of the raw tube 1.

  Next, a conventional method for manufacturing an internally grooved tube will be described. As shown in FIG. 3, first, the drawing oil 10 is filled on the upstream side of the holding plug 2 inside the base tube 1. The base tube 1 is reduced in diameter by the holding plug 2 and the holding die 3. Next, the outer surface of the diameter-reduced raw tube 1 is reduced in diameter by being pressed by a rolling roll 6 that rolls in contact with the outer surface and rotates, and is pressed toward the grooved plug 15. Thereby, the groove of the grooved plug 15 is transferred to the inner surface of the raw tube 1. At this time, the grooved plug 15 is connected to the holding plug 2 via the plug shaft 4, and the holding plug 2 is aligned with the holding die 3 by the frictional force caused by the drawing of the raw tube 1 and the drag from the holding die 3. Since it is locked at the position, the grooved plug 15 is also stopped at a position aligned with the rolling roll 6. Next, the raw tube 1 in which the groove is formed on the inner surface that has passed through the rolling portion 17 is further reduced in diameter by the sizing die 8 and shaped so that the cross section of the tube axis is a perfect circle. The inner grooved tube 9 has an outer diameter.

  In the conventional method of manufacturing an internally grooved tube, lubricating oil is supplied to the outer surface of the raw tube 1 in the diameter reducing process by the holding die 3, the sizing die 8 and the rolling part 17. The role of this lubricating oil is to reduce friction and wear, to suppress seizure and to cool, etc. In addition to these functions, the lubricating oil is difficult to remain when annealing the internally grooved tube after processing. In addition, low smoke generation is required. As this lubricating oil, generally, a lubricating oil (hereinafter referred to as a mineral-based lubricating oil) in which a synthetic polymer compound and an oil improver are added to mineral oil to improve lubricity and viscosity is used. Moreover, after the raw tube 1 is processed into the inner grooved tube 9, the lubricating oil on the outer surface of the tube is removed. The removed lubricating oil is recovered and reused.

  Thus, in the roll rolling method, since no rolling ball is used, a magnetic levitation type high-speed motor for rotating the rolling ball is unnecessary. For this reason, equipment cost can be held down. Further, since no rolling ball is used, the drawing speed of the pipe is not determined by the revolution speed of the rolling ball. For this reason, the drawing speed of the pipe can be improved and the productivity can be improved.

Japanese Patent Publication No. 3-5882 (Page 2-4, Fig. 1) JP-A-1-99713 (page 2-5, FIG. 1) JP-A-4-302999 (page 3-4, Fig. 1-2)

  However, the conventional techniques described above have the following problems. As the raw tube 1 is processed, the raw tube 1 generates heat. Thereby, the temperature of each tool which processes the raw tube 1 rises, and it thermally expands. In particular, when the grooved plug 15 and the rolling roll 6 are thermally expanded, the rolling load is changed, and the shape of the groove formed on the inner surface of the raw tube 1 at the start of processing and the end of processing, that is, the groove depth and There is a problem that the bottom wall thickness changes. Further, there is a problem that the rolling load increases, exceeds the breaking load of the raw tube 1, and the raw tube 1 breaks during processing.

  The present invention has been made in view of such a problem, and an apparatus for manufacturing an internally grooved tube capable of preventing a shape change and breakage of a raw tube due to a change in rolling load, and an internal surface groove using the manufacturing apparatus. It aims at providing the manufacturing method of a tube.

  An apparatus for manufacturing an internally grooved tube according to the first invention of the present application includes a holding die that contacts an outer surface of a metal tube, and the metal tube that is disposed inside the metal tube and is engaged with the holding die, together with the holding die. A holding plug for reducing the diameter, a grooved plug that is rotatably supported on the plug shaft of the holding plug and has a groove formed on the outer surface, and a rotating shaft that is parallel to the outer surface of the metal tube and A pair of rolling rolls arranged so as to be orthogonal to the tube axis direction and rollingly contacting the outer surface of the metal tube to press the metal tube toward the grooved plug to form a groove on the inner surface of the metal tube; A sizing die that is arranged downstream of the pair of rolling rolls in the drawing direction of the metal tube and contacts the outer surface of the metal tube to reduce the diameter of the metal tube, and an upstream side in the drawing direction of the metal tube than the holding die Of the metal tube in A first supply means for supplying a first lubricant to the surface, and a second lubrication having a higher cooling performance than the first lubricant on the outer surface of the metal tube between the holding die and the rolling roll pair. And a second supply means for supplying oil.

  In the present invention, the dynamic friction coefficient between the holding plug and the base tube is reduced by using the first lubricating oil as a lubricating oil having excellent lubricity and the second lubricating oil as a lubricating oil having excellent cooling performance. At the same time, the temperature rise of the rolling roll and the groove plug in the rolling part can be suppressed, and the thermal expansion of the rolling roll and the groove plug can be suppressed. As a result, it is possible to prevent the tube from being broken during processing, to prevent fluctuations in the groove shape at the start and end of processing, and to manufacture an internally grooved tube with a stable groove shape. .

  As the first lubricating oil, for example, a lubricating oil containing mineral oil can be used, and as the second lubricating oil, for example, a water-soluble emulsion can be used.

  The rolling part and the sizing die comprising the grooved plug, the rolling roll pair, and the second supply means may be arranged in a plurality of stages along the drawing direction of the metal tube. Thereby, a groove | channel can be formed more uniformly in a metal pipe inner surface. Also, multiple types of grooves can be formed on the inner surface of the metal tube.

  The rolling part comprising the grooved plug, the rolling roll pair and the second supply means is arranged in two stages in the drawing direction of the metal tube, and the opposing direction of the rolling roll pair in each rolling part is orthogonal to each other. The opposing direction of at least one of the rolling roll pairs can be changed by the angle θ from the orthogonal basic position. This angle θ is, for example, in the range of 0 to 90 °. Thereby, a groove | channel can be formed more uniformly in a metal pipe inner surface.

  A pair of backup rolls having a diameter larger than that of the rolling roll and pressing the rolling roll in the direction of the metal tube may be in rolling contact with the rolling roll pair. Thereby, the force with which the rolling roll presses the metal tube is made uniform.

  According to a second aspect of the present invention, there is provided a method of manufacturing an inner surface grooved tube, the first supply means supplying a first lubricant to the outer surface of the metal tube, a holding die disposed outside the metal tube, Reducing the diameter of the metal tube after the first lubricant is supplied by a holding plug disposed in the tube and engaging the holding die, and removing the first lubricant from the outer surface of the metal tube; Supplying a second lubricating oil having a cooling performance higher than that of the first lubricating oil to the outer surface of the metal pipe by a second supplying means; and rotatably supporting the plug shaft of the holding plug on the outer surface. The groove is formed by a grooved plug and a pair of rolling rolls arranged on the outer surface of the metal tube so that the rotation axes are parallel to each other and perpendicular to the tube axis direction of the metal tube. A process for forming grooves in the inner surface of the metal tube by pressing against the attached plug When, characterized in that it and a step of removing the second lubricating oil from the outer surface of the metal tube is performed with the diameter reduction to the metal pipe by a sizing die.

  In the present invention, by using a lubricating oil having excellent lubricity for the holding plug and using a lubricating oil having excellent cooling performance for the rolling roll, the dynamic friction coefficient between the holding plug and the raw pipe is reduced, The temperature rise of the rolling roll and the groove plug in the rolling part can be suppressed, and the thermal expansion thereof can be suppressed. As a result, the pipe can be prevented from breaking during processing, and the groove shape can be prevented from fluctuating between the start and end of processing, and the grooved inner surface has excellent groove formability. Tubes can be manufactured.

  For example, a lubricating oil containing mineral oil is used as the first lubricating oil, and a water-soluble emulsion is used as the second lubricating oil, for example.

  The grooved plug, the rolling roll pair, and the sizing die including the second supply unit and the sizing die are arranged in a plurality of stages along the drawing direction of the metal tube, and the second lubricating oil is used. The step of supplying, the step of forming the groove and the step of reducing the diameter by the sizing die and removing the second lubricating oil may be performed a plurality of times. Thereby, a groove | channel can be formed more uniformly in a metal pipe inner surface. Also, multiple types of grooves can be formed on the inner surface of the metal tube.

  Furthermore, the rolling part composed of the grooved plug, the rolling roll pair and the second supply means is arranged in two stages in the drawing direction of the metal tube, and the opposing direction of the rolling roll pair in each rolling part is mutually The at least one pair of rolling rolls can change the opposing direction from the orthogonal basic position by an angle θ. This angle θ is preferably in the range of 0 to 90 °. Thereby, a groove | channel can be formed more uniformly in a metal pipe inner surface.

  Furthermore, a pair of backup rolls having a diameter larger than that of the rolling roll may be rolled on the rolling roll pair, and the rolling roll is pressed in the direction of the metal tube by the backup roll. Thereby, the said metal tube can be uniformly pressed with the said rolling roll.

  According to the present invention, by using a lubricating oil having excellent lubricity for the holding plug and using a lubricating oil having excellent cooling performance for the rolling roll, the dynamic friction coefficient between the holding plug and the raw pipe is reduced. Prevents the tube from breaking and suppresses the temperature rise of the rolling roll and groove plug in the rolling part to stabilize the rolling load, preventing the groove shape from fluctuating between the start and end of processing. be able to.

  Hereinafter, an internal grooved pipe manufacturing apparatus according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a manufacturing apparatus and manufacturing method for an internally grooved tube according to an embodiment of the present invention. 1 that are the same as those of the conventional apparatus shown in FIGS. 3 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 1, the inner surface grooved pipe manufacturing apparatus of the present embodiment includes a holding plug 2, a grooved plug 5a via a plug shaft 4, and a grooved plug 5b having a smaller diameter than the grooved plug 5a. Are connected. These grooved plugs 5a and 5b are rotatably attached to each other, and grooves having a shape to be formed on the inner peripheral surface of the raw tube 1 are processed on the outer peripheral surface thereof. The grooved plugs 5a and 5b are preferably made of an ultrafine particle superalloy, and more preferably an ultrafine particle alloy containing tungsten carbide (WC) fine particles having a diameter of 0.5 μm or less, for example. .

  In addition, a pair of work rolls (rolling rolls) 16a having rotating shafts parallel to each other are positioned at a position aligned with the grooved plug 5a on the outer side of the raw tube 1, and at a position aligned with the grooved plug 5b. A pair of work rolls 16b having parallel rotation axes are arranged so as to make rolling contact with the outer surface of the raw tube 1 respectively. In the work roll pairs 16a and 16b, the direction in which their rotation axes extend is perpendicular to the tube axis direction of the raw tube 1, and the opposing direction of the work roll pair 16a and the opposing direction of the work roll pair 16b are mutually orthogonal. (This position is hereinafter referred to as a basic position). In this manufacturing apparatus, the facing direction of at least one of the work roll pairs 16a and 16b can be changed by the angle θ from the basic position described above. This angle θ is, for example, in the range of 0 to 90 °. Further, the work rolls 16a and 16b can rotate, and the shape thereof is a drum shape whose both end portions are thick and whose central portion is thin. In this manufacturing apparatus, in the cross section including the rotation axis, the radius of curvature of the side surface is substantially equal to the radius of the outer surface of the tube 1, and the shape of the side edges thereof substantially matches the shape of the outer surface of the tube 1. The work rolls 16a and 16b are in line contact with the base tube 1 substantially evenly.

  Further, a pair of backup rolls 18a having a diameter larger than that of the work roll 16a and pressing the work roll 16a in the direction of the raw tube 1 are arranged so as to be in rolling contact with the work roll 16a. Similarly, a pair of backup rolls 18b that are larger in diameter than the work roll 16b and press the work roll 16b in the direction of the raw tube 1 are disposed so as to be in rolling contact with the work roll 16b. Thus, force can be uniformly applied to the raw tube 1 by pressing the work roll with the backup roll. The above-mentioned work roll and backup roll can be made of, for example, cemented carbide or bearing steel such as SUJ-2. The rolled portion 7a is formed by the grooved plug 5a, the work roll pair 16a, and the backup roll pair 18a, and the rolled portion 7b is formed by the grooved plug 5b, the work roll pair 16b, and the backup roll pair 18b.

  A sizing die 8a for forming the raw tube 1 is provided between the first-stage rolled portion 7a and the second-stage rolled portion 7b. On the downstream side in the drawing direction, there is provided a sizing die 8b for processing the outer diameter of the raw tube 1 having a groove formed on the inner surface into a predetermined dimension. That is, the manufacturing apparatus used in the method for manufacturing an internally grooved tube according to this embodiment is an apparatus of a dandem rolling method in which two stages of rolling rolls are provided.

  In addition, the inner surface grooved pipe manufacturing apparatus of the present embodiment includes a lubricating oil supply device 24 that includes a nozzle 22 that supplies the lubricating oil 20 to the outer surface of the raw tube 1, and a nozzle 23 that supplies the lubricating oil 21. A lubricating oil supply device 25 is also provided. The nozzle 21 is arranged upstream of the holding die 3 in the tube drawing direction, and the nozzle 23 is arranged upstream of the work rolls 16a and 16b and the sizing dies 8a and 8b in the tube drawing direction. In addition, the structure other than the above in the manufacturing apparatus of the internally grooved tube of the present embodiment is the same as that of the conventional manufacturing apparatus shown in FIGS.

  Next, the operation of the inner grooved pipe manufacturing apparatus configured as described above, that is, the inner grooved pipe manufacturing method according to the present embodiment will be described. In the method for manufacturing an internally grooved tube of the present embodiment, as shown in FIG. 1, first, the raw tube 1 is installed at a predetermined position of the manufacturing apparatus configured as described above. Any material can be used for forming the raw tube 1 as long as it is a metal that can be processed into a tube. For example, H material such as copper or copper alloy having good heat conductivity and workability is used, and in particular, JIS H 3300. C1201 and C1220 defined in the above are suitable. Next, the drawing oil 10 is filled on the upstream side of the holding plug 2 inside the base tube 1. Then, a pulling force is applied to the raw tube 1 in the tube pulling direction, and the raw tube 1 is pulled out. Thereby, a delivery apparatus (not shown) pays out the raw tube 1, and the raw tube 1 starts moving along the drawing direction. The raw tube 1 is processed into an internally grooved tube 19 by sequentially passing through the holding die 3, the rolling portion 7a, the sizing die 8a, the rolling portion 7b, and the sizing die 8b. Hereinafter, the process which a certain part of the raw tube 1 performs with a movement is demonstrated in detail.

  First, the lubricating oil 20 is supplied to the outer surface of the raw pipe 1 by the nozzle 22 on the upstream side of the holding die 3 in the pipe drawing direction. The lubricating oil 20 has excellent lubricity, and for example, mineral oil-based lubricating oil is used. Specifically, Idemitsu Kosan Co., Ltd. Daphne Master Draw 533WD or Daphne Master Draw 560 can be used. The holding die 3 holds the holding plug 2 on the inner surface of the raw tube 1, and the grooved plugs 5 a and 5 b are connected to the holding plug 2 via the plug shaft 4. Has a large tensile stress in the tube axis direction. Moreover, since the drawing speed of the raw tube 1 that passes through the holding die 3 exceeds 100 m / min, the value of the dynamic friction coefficient between the holding die 3 and the raw tube 1 increases. Therefore, the holding die 3 requires a lubricating oil having excellent lubricity (an oil film that is difficult to break). Therefore, in the manufacturing method of the internally grooved tube of the present embodiment, the holding die 3 uses a mineral oil-based lubricant that reduces the frictional resistance. The raw tube 1 is reduced in diameter by the holding die 3 and the holding plug 2, and the lubricating oil 20 is removed from the outer surface of the raw tube 1. The removed lubricating oil 20 is recovered and reused.

Next, the lubricating oil 21 is supplied to the outer surface of the raw tube 1 by the nozzle 23 upstream of the work roll 16a in the tube drawing direction. The lubricating oil 21 has better cooling performance than the lubricating oil 20, and for example, a water-soluble emulsion is used. Specifically, Stroke C ₆ S manufactured by Kyoei Oil Chemical Co., Ltd. can be used. In the rolled portion 7a, the work roll 16a expands due to processing heat generated by the raw tube 1, heat generated by friction between the work roll 16a and the raw tube 1, and the rolling load changes. For this reason, if the same lubricating oil as the holding die 3 is used, heat generation cannot be suppressed. Therefore, in the manufacturing method of the inner surface grooved tube of the present embodiment, a water-soluble lubrication having a higher cooling capacity than the lubricating oil used for the holding die 3 described above, for example, a higher heat capacity than the mineral lubricating oil described above. Use oil. In this water-soluble lubricating oil, the oil portion has a lubricating action, and the water portion has a cooling action. Thereby, the groove workability in the internally grooved tube 19 can be improved.

  In the first-stage rolled portion 17a, the work roll 16a rotates while pressing the workpiece tube 16a by rotating the backup roll 18a while pressing the work roll 16a. Thereby, the groove on the outer surface of the grooved plug 5 a is transferred to the inner surface of the raw tube 1, and a groove is formed on the inner surface of the raw tube 1. In the manufacturing method of the internally grooved tube of this embodiment, the rolling load is controlled by a backup roll. Next, the raw tube 1 is reduced in diameter by the sizing die 8 a and the lubricating oil 21 is removed from the outer surface of the raw tube 1. The removed lubricating oil 21 is recovered and reused.

  Next, the lubricating oil 21 is supplied to the outer surface of the raw tube 1 by the nozzle 23 on the upstream side of the work roll 16b in the tube drawing direction. In the second-stage rolled portion 17b, the backup roll 18b rotates while pressing the work roll 16b, so that the work roll 16b rotates while pressing the raw tube 1. Thereby, the groove on the outer surface of the grooved plug 5 b is transferred to the inner surface of the raw tube 1, and a groove is formed on the inner surface of the raw tube 1. Next, the raw tube 1 is reduced in diameter by the sizing die 8b and shaped to a predetermined outer diameter, and the lubricating oil 21 is removed from the outer surface of the raw tube 1 to form the inner grooved tube 19. At this time, the processing rate (reduction rate) in the sizing die 8b is set to 20% or less, and the drawing speed immediately after the sizing die 8b is set to 5 m / second or less. Water-soluble lubricating oil has higher cooling performance than mineral-based lubricating oil, but may have poor lubricity. Therefore, by increasing the processing rate in the sizing die 8b and the drawing speed immediately after the sizing die 8b within the above ranges, an increase in the dynamic friction coefficient between the raw tube 1 and the sizing die 8b is suppressed. Thereby, it is possible to prevent the tube from being broken due to an increase in the pulling load due to an increase in the dynamic friction coefficient between the base tube 1 and the sizing die 8b. The removed lubricating oil 21 is recovered and reused.

  The temperatures of the lubricating oils 21 and 22 used in the method for manufacturing an internally grooved tube of this embodiment are preferably 10 to 35 ° C., and the variation is preferably within ± 5 ° C. For this reason, when recovering and circulating the lubricating oil, the recovered lubricating oil is stored in a tank, and the oil temperature is controlled so as to be within the temperature range. Further, the amounts of the lubricating oils 20 and 21 supplied by the nozzles 22 and 23 are changed in accordance with the processing rate (the diameter reduction rate) and the rotation speed of the work rolls 16a and 16b. Furthermore, in the holding die 3, it is not always necessary to completely remove the lubricating oil 20 from the outer surface of the raw tube 1, and the lubricating oil 21 recovered in the sizing dies 8a and 8b can be removed to such an extent that it can be reused without greatly deteriorating. That's fine.

  In the manufacturing method of the inner surface grooved tube of the present embodiment, the grooved plugs 5a and 5b are connected to the holding plug 2 through the plug shaft 4, and the holding plug 2 is obtained by pulling out the raw tube 1. The grooved plugs 5a and 5b are also stopped at the positions where they are aligned with the work rolls 16a and 16b because the frictional force and the drag from the holding die 3 are locked at the positions where they are aligned with the holding dies 3.

  In general, the raw tube 1 grooved by the rolled portion 7a is somewhat twisted by the rotation of the fluted plug 5a provided in the rolled portion 7a. Generally, the second-stage rolled portion 7b is installed to form a groove in a region where the groove is not formed in the rolled portion 7a. For example, when groove processing is performed on the upper and lower halves of the raw tube 1 at the rolling portion 7a, if the raw tube 1 is not twisted, the rotation axis of the work roll 16a and the rotation axis of the work roll 16b May have an angle of 90 ° in the cross section perpendicular to the drawing direction of the tube 1. However, in actuality, as described above, when the raw tube 1 that has been grooved by the rolled portion 7a reaches the position of the rolled portion 7b, the region in which no groove is formed is displaced due to twisting. .

  So, in the manufacturing method of the inner surface grooved pipe of this embodiment, among the work roll pairs 16a and 16b, a groove is formed in a region where the groove is not formed in the rolled portion 7a in the rolled portion 7b. The facing direction of at least one work roll pair is changed by an angle θ from the basic position described above. This angle θ can be appropriately set within the range of 0 to 90 ° in consideration of the shape of the groove to be formed, processing conditions, and the like.

  Hereinafter, the effect of the Example of this invention is demonstrated compared with the comparative example which remove | deviates from the scope of the present invention. As an embodiment of the present invention, a tandem rolling manufacturing apparatus shown in FIG. 1 and a single manufacturing apparatus with one rolling part are used to change the combination of lubricating oils, and an inner groove is formed on a 2000 m long pipe. The inner grooved tube was manufactured by processing. The processing conditions at that time are shown in Tables 1 and 2.

Incidentally, the rolling working ratio shown in Table 1 D (%) is the rate of change of the cross-sectional area of the tube before and after the rolling, the cross-sectional area of mother tube before rolling and S _1, the sizing die immediately after rolling roll the cross-sectional area of the tube after passing through a S _2, is determined by equation 1 below. However, the cross-sectional area S ₁ of the mother tube before rolling, if roll is one stage, the cross-sectional area of the element tube after the diameter reduction by the holding die and holding the plug, when the roll is 2-stage 1-stage It was set as the cross-sectional area of the pipe | tube after rolling by the roll of eyes, and passing the sizing die immediately after that. Further, the sectional area S ₂ of the tube after passing through the sizing die, if the roll is a single-stage, and the cross-sectional area of the tube after passing through the first stage rolls and immediately after the sizing die, roll in two stages In this case, the cross-sectional area of the tube after passing through a roll having two cross sections and a sizing die immediately after that was used. The cross-sectional areas S ₁ and S ₂ were obtained from the mass and specific gravity of the tube after temporarily stopping rolling at each stage.

Further, the total working ratio T (%) shown in Table 1 is the change ratio of the external diameter of the pipe before and after processing an inner grooved, the outer diameter of the mother tube before processing and L _0, after passing through the sizing die The outer diameter of the pipe is calculated from the following formula 2 with Lr. However, the outer diameter of the tube after passing through the sizing die is Lr. When the roll is one stage, the outer diameter of the pipe after passing through the first stage roll and the sizing die immediately after that is used. Is the outer diameter of the tube after passing through the second stage roll and the sizing die immediately thereafter.

  In this example, Idemitsu Kosan Co., Ltd. Daphne Master Draw WD was used as the mineral-based lubricating oil, and Kyoei Oil C6S, which is an aqueous emulsion, was used as the high cooling performance oil. Under the conditions shown in Tables 1 and 2 above, the inner surface grooved pipes of Examples and Comparative Examples produced by changing the combination of lubricating oils, the amount of change in shape, the roll base oil speed, the drawing speed, the pipe temperature immediately after processing, The presence or absence of breakage was confirmed. The results are shown in Table 3. In addition, the shape change amount shown in Table 3 below is the difference in the groove depth of the deepest portion of the grooved portion in the internally grooved tube taken from the rolling start portion and the end portion, and the smaller the difference, the better.

  As shown in Table 3, Comparative Example 1 using a single-type manufacturing apparatus and using a mineral-based lubricating oil for both the holding die and the rolling part did not break, but the final tube temperature was 195 ° C. It was high and the amount of shape change was large. Further, in Comparative Example 2 using a tandem manufacturing apparatus and using a mineral lubricating oil for both the holding die and the rolling part, the final pipe temperature is as high as 224 ° C., and the amount of change in shape in both the first and second stages. The tube was broken. Further, in Comparative Example 3 in which a mineral lubricant was used for both the holding die and the rolling part, and the drawing speed and roll peripheral speed were higher than those of Comparative Example 2 described above, the tube broke during processing. On the other hand, in Examples 1 and 3 using a single-type and tandem-type manufacturing apparatus, a mineral oil for the holding die, and a water-soluble emulsion for the rolling part, the final tube temperature was as low as 84 ° C, and the shape change The amount was also small. Similarly, Examples 2 and 4 in which the mineral oil is used for the holding die and the water-soluble emulsion is used for the rolling part, and the drawing speed and the roll peripheral speed are made faster than those in Examples 1 and 3 are the final pipes. It was possible to produce an internally grooved tube having a temperature of 100 ° C. or less and a small amount of change in shape without breaking the tube.

  Next, a 3400 m inner grooved tube was manufactured under the same conditions as in Example 3 and Comparative Example 2, and the temperature change of the raw tube was examined. The results are shown in Table 4. FIG. 2 shows the processing length and the temperature of the pipe when the internally grooved tube is manufactured under the conditions of Example 3 and Comparative Example 2 with the processing length on the horizontal axis and the temperature of the pipe on the vertical axis. It is a graph which shows the relationship.

  As shown in FIG. 2 and Table 4, in Comparative Example 2 in which mineral oil was used for both the holding plug and the rolled part, the temperature of the raw pipe increased in proportion to the processing length, and reached 224 ° C. at 1200 m. After that, the tube broke. On the other hand, in Example 3 in which a mineral-based lubricating oil having a high lubricating performance was used for the holding plug and an aqueous emulsion having a high cooling performance was used for the rolled part, the temperature of the raw tube rose to about 80 ° C., but thereafter It was kept between 80 and 85 ° C. As a result, a 3400 m inner grooved tube could be manufactured without breaking the tube.

It is sectional drawing which shows the manufacturing apparatus and manufacturing method of an internal grooved pipe of embodiment of this invention. A graph showing the relationship between the processing length and the tube temperature in the case where an internally grooved tube was manufactured under the conditions of Example 3 and Comparative Example 2, with the processing length on the horizontal axis and the tube temperature on the vertical axis. FIG. It is sectional drawing which shows the manufacturing apparatus and manufacturing method of a seamless inner surface grooved pipe by the conventional roll rolling method. It is an expanded sectional view which shows the rolling part of the manufacturing apparatus shown in FIG. It is sectional drawing by the AA line shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Elementary pipe 2; Holding plug 3; Holding die 4; Plug shaft 5a, 5b, 15; Grooved plug 6; Rolling roll 7a, 7b, 17; Rolled part 8, 8a, 8b; Sizing die 9, 19; Internal grooved tube 10; Drawing oil 11; Cylindrical part 12; Tapered part 16, 16a, 16b; Work roll 18a, 18b; Backup roll 20, 21; Lubricating oil 22, 23; Nozzle 24, 25;

Claims (12)

A holding die that contacts the outer surface of the metal tube, a holding plug that is disposed inside the metal tube and engages with the holding die and reduces the diameter of the metal tube together with the holding die, and a plug shaft of the holding plug A grooved plug that is rotatably supported and has grooves formed on the outer surface thereof, and an outer surface of the metal tube that is disposed on the outer surface of the metal tube so that the rotation axes are parallel to each other and perpendicular to the tube axis direction of the metal tube. And a pair of rolling rolls that press the metal tube toward the grooved plug to form grooves on the inner surface of the metal tube, and are arranged downstream of the rolling roll pair in the drawing direction of the metal tube. And a sizing die for reducing the diameter of the metal tube in contact with the outer surface of the metal tube, and supplying a first lubricating oil to the outer surface of the metal tube on the upstream side in the drawing direction of the metal tube with respect to the holding die. First supply means And a second supply means for supplying a second lubricating oil having a cooling performance higher than that of the first lubricating oil to an outer surface of the metal tube between the holding die and the pair of rolling rolls. An inner grooved pipe manufacturing apparatus. The apparatus for producing an internally grooved tube according to claim 1, wherein the first lubricating oil is a lubricating oil containing mineral oil, and the second lubricating oil is a water-soluble emulsion. 2. The rolling part comprising the grooved plug, the rolling roll pair and the second supply means, and the sizing die are arranged in a plurality of stages along the drawing direction of the metal tube. Or the manufacturing apparatus of the inner surface grooved pipe of 2. The rolling part comprising the grooved plug, the rolling roll pair and the second supply means is arranged in two stages in the drawing direction of the metal tube, and the opposing direction of the rolling roll pair in each rolling part is orthogonal to each other. 4. The apparatus for producing an internally grooved tube according to claim 3, wherein at least one of the rolling roll pairs can change the facing direction by an angle θ from the orthogonal basic position. The apparatus for producing an internally grooved tube according to claim 4, wherein the angle θ is in the range of 0 to 90 °. 6. The rolling roll pair is in contact with a pair of backup rolls having a diameter larger than that of the rolling roll and pressing the rolling roll in the metal tube direction. An apparatus for producing an internally grooved tube according to Item. The step of supplying the first lubricating oil to the outer surface of the metal tube by the first supply means, the holding die disposed outside the tube of the metal tube, and the holding plug disposed in the tube and engaged with the holding die The step of reducing the diameter of the metal tube after the supply of the first lubricating oil and removing the first lubricating oil from the outer surface of the metal tube; and the first supply on the outer surface of the metal tube by a second supply means. Supplying a second lubricating oil having a cooling performance higher than that of the lubricating oil, a grooved plug rotatably supported on the plug shaft of the holding plug and having a groove formed on the outer surface, and an outer surface of the metal tube A groove is formed on the inner surface of the metal tube by pressing the metal tube against the grooved plug by a pair of rolling rolls arranged so that the rotation axes are parallel to each other and perpendicular to the tube axis direction of the metal tube And the metal tube is reduced by a sizing die. Method for manufacturing inner grooved tube, characterized in that and a step of removing the second lubricating oil from the outer surface of the metal tube with subjected to processing. The method for manufacturing an internally grooved tube according to claim 7, wherein a lubricating oil containing a mineral oil is used for the first lubricating oil, and a water-soluble emulsion is used for the second lubricating oil. A rolling part comprising the grooved plug, the rolling roll pair and the second supply means and the sizing die are arranged in a plurality of stages along the drawing direction of the metal tube, and supply the second lubricating oil. 9. The grooved inner surface according to claim 7, wherein the step of forming the groove, the step of reducing the diameter by the sizing die and the step of removing the second lubricating oil are performed a plurality of times. A method of manufacturing a tube. The rolling part comprising the grooved plug, the rolling roll pair and the second supply means is arranged in two stages in the drawing direction of the metal tube, and the opposing direction of the rolling roll pair in each rolling part is orthogonal to each other. 10. The method for producing an internally grooved tube according to claim 9, wherein at least one of the rolling roll pairs can change the opposing direction from the orthogonal basic position by an angle θ. 11. The method for manufacturing an internally grooved tube according to claim 10, wherein the angle [theta] is in the range of 0 to 90 [deg.]. The pair of rolling rolls is in contact with a pair of backup rolls having a larger diameter than the rolling rolls, and the rolling rolls are pressed in the direction of the metal tube by the backup rolls. The manufacturing method of the inner surface grooved pipe of any one of thru | or 11.

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