JP4375620B2 - Tapered tube manufacturing method - Google Patents

Description

  The present invention relates to a method of manufacturing a tapered tube using a spinning method.

  Metal pipes such as steel pipes are widely used indoors and outdoors as members of buildings such as lighting pillars and mechanical devices. However, in terms of design and landscape, all or part of the length of the pipe In these cases, a tapered tube whose outer diameter changes continuously has been used.

  Tapered pipes whose outer diameter continuously changes over the entire length of the pipe are drawn by gradually reducing the outer diameter by drawing (cold or hot) a circular pipe of the same outer diameter with a press and a die. It has been manufactured by making a frustum-shaped tube or a frustum-shaped tube by cutting a metal plate into a trapezoid and wire-welding between both sides thereof. However, only a short circular tube can be formed into a truncated cone shape by drawing (cold or hot) with a press and a die, and it is formed by cutting a metal plate into a trapezoid and welding its sides. However, the truncated cone-shaped tube requires not only a process of cutting into a trapezoid but also a process of welding it, which is troublesome and increases costs.

  A tapered tube whose outer diameter continuously changes at some points in the length direction of the tube is also called a “stepped tube”, and it has a truncated cone shape by drawing (cold or hot) with a press and a die. It has been manufactured by circumferentially welding a circular tube having the same outer diameter as that of one end or both ends of the short tube. However, in addition to the necessity of the step of circumferential welding, there are problems that the cost is high due to the large number of members and that the welded portion impairs the appearance.

  In order to solve these problems, a metal pipe such as a steel pipe is used as a base pipe, and two or three forming rollers for drawing (reducing diameter) processing on the base pipe are arranged on the outer periphery of the base pipe. A method has been proposed in which a tapered tube is continuously manufactured by performing a spinning process in which a tube is relatively moved in the tube axis direction and a forming roller is moved forward and backward in the tube radial direction with respect to a rotating raw tube. Yes.

  For example, Patent Document 1 discloses a method for manufacturing a tapered tube by spinning as follows.

  First, the central axis of rotation of the forming roller is inclined with respect to the central axis of the raw tube so that the shoulder can be drawn and the raw tube can be rotated. Alternatively, it is rotated by a separately installed rotational drive device. Then, the raw tube is moved horizontally in the tube axis direction by a pulling carriage or the like, or the forming roller is moved horizontally and in the tube radial direction while fixing one end of the raw tube. Further, the raw tube is heated to a predetermined molding temperature by installing a heating device in the previous stage of the molding roller. Thus, a taper pipe | tube can be continuously manufactured by performing a continuous diameter reduction process between hot with a forming roller in the state to which the heated elementary pipe rotated and the tension | tensile_strength was provided.

  Further, in Patent Document 2, since a spiral linear mark may be formed on the tube surface by spinning, a pressing roller is provided at a later stage of the forming roller, and the pressing roller is driven to drive the pressing roller. A method of erasing spiral line marks by pressing the outer peripheral surface against the tube surface is disclosed.

JP 2002-292432 A JP 2002-292433 A

  FIG. 1 shows an example (side view) of a spinning machine used when a tapered tube is manufactured by spinning.

Spinning machine, placed at equal intervals on the outer circumference of the mother tube P ₀ in the pipe circumferential direction and the forming roller 1 comprising a plurality of rolls arranged to be inclined with respect to the central axis L ₀ of the mother tube P ₀ A heating device 2 installed in the front stage of the molding roller 1 and a support roller 3 installed in a front stage and a rear stage of the molding roller 1 and made up of a non-driving roll that can rotate the raw pipe P ₀ in the pipe circumferential direction; , and a tensile carriage 4 moves the base pipe P ₀ in the horizontal direction via a grasping mechanism for grasping an end portion of the base pipe P ₀ (not shown). Further, in this example, a pressing roller 5 composed of a driving roll is installed between the forming roller 1 and the support roller 3.

Here, the roll which comprises the shaping | molding roller 1 is a disk type drive roll of the outer diameter D, is connected to a motor (not shown), and is driven. The rotation center axis L ₁ of the drive roll constituting the forming roller is directed to the rotation center axis L ₀ of the raw tube P ₀ and is inclined to the opposite side to the tube moving direction at an inclination angle α with respect to the center axis L ₀ . This is the mounting angle α of the drive roll constituting the forming roller. By this inclination, the raw tube P ₀ can be rotated and the drawing process can be performed at the shoulder portion. Instead of rotating the blank tube P ₀ by the forming roller 1, a portion of the support roller 3 which is arranged in front of the forming roller by a drive roll may rotate the mother pipe P _0. Therefore, the raw tube P ₀ is not necessarily rotated by the forming roller 1. The pressing roller 5 is installed in preparation for the case where a spiral linear mark is formed on the tube surface by spinning, and when the spiral linear mark is conspicuous, the pressing roller 5 is driven to rotate. As a result, spiral line marks can be erased. Therefore, the pressing roller 5 is not necessarily installed in the spinning machine.

  Using this spinning machine, a tapered pipe can be manufactured by spinning a raw pipe made of a circular pipe. Next, an example of a procedure in the case of using a spinning machine having three rolls constituting the forming roller will be shown.

While the base pipe P ₀ of the outer diameter R ₀ is moved to the left in FIG. 1 by the pulling carriage 4, as well as pressure at the shoulder portion of the forming roller 1 with respect to base pipe P ₀ heated in the heating device 2, containing Corresponding to the movement of the pipe P ₀ , the forming roller 1 is gradually advanced (reduced diameter movement) relative to the raw pipe P ₀ . The raw tube P ₀ is rotated by the rotational driving of the forming roller 1, and hot spinning is performed by the forming roller 1 in a state where a tensile force is applied to the raw tube P ₀ by the pulling carriage 4. In this way, it is possible to manufacture a tapered tube having a tapered portion whose diameter gradually decreases toward the right side of FIG. Here, by adjusting the moving speed of the raw tube P ₀ , the advance moving speed of the forming roller 1, etc., the taper rate can be varied in the range of 1/35 to 1/200, for example. The taper ratio may be kept constant during processing, or may be changed during processing. In addition, there is no special restriction | limiting in the attachment angle (alpha) of the drive roll which comprises a shaping | molding roller. It is preferable to attach in the range of 15 to 40 °. The most desirable mounting angle α is around 30 °.

  As described above, by subjecting a circular pipe made of spinning to a spinning process, tapered pipes having various shapes can be manufactured at low cost without performing a welding operation.

  For example, a taper tube whose outer diameter continuously changes at a part of the tube length direction, that is, a stepped tube, is used for the lamp mounting portion (adapter) at the tip of the lighting column. A stepped tube can be manufactured by spinning a base tube made of a circular tube.

FIG. 2 is an example of a stepped tube used for the adapter. This stepped pipe has a taper portion P ₁ having a tube length L that gradually changes from a maximum outer diameter Rmax to a minimum outer diameter Rmin, a straight portion P ₁ that is continuous on both sides thereof, and has a constant outer diameter Rmax and an outer portion. diameter is from certain of the straight portion P ₃ at Rmin. When used as an adapter at the tip of an illuminating column, the taper portion has a maximum outer diameter Rmax = 75 to 120 mm, a taper portion has a minimum outer diameter Rmin = 55 to 100 mm, a tube thickness = 3.2 to 6.0 mm, The tube length L is about 20 to 45 mm. Preferably, Rmax = 75.0 to 100 mm, Rmin = 55 to 85 mm, tube thickness = 4.2 to 6.0 mm, and L = 20 to 35 mm. Most preferably, the taper portion has a maximum outer diameter Rmax = 60.5 to 90 mm, the taper portion has a minimum outer diameter Rmin = 55 to 60.5 mm, a tube thickness = 3.2 to 6.0 mm, and a tube length L of the taper portion. = About 25 to 35 mm.

By the way, in the spinning machine, the number of the forming rollers 1 in which the driving rolls are inclined and arranged at equal intervals on the outer periphery of the raw tube P ₀ is usually two or three. Has a point.

  When a spinning processing machine in which the forming roller 1 is composed of two rolls is used, the outer diameter of the roll can be increased and the amount of reduction can be increased, so that the processing speed of the spinning process can be increased. However, the control of the roll position alone cannot determine the outer diameter of the tapered portion after processing, and the so-called “angularity” occurs in the spinning process, so that the taper after the processing is performed. There was a problem that the cross section of the portion did not become circular.

  On the other hand, when a spinning processing machine in which the forming roller 1 is composed of three rolls is used, the outer diameter of the tapered portion after processing can be determined only by controlling the position of the roll.

Here, since the forming roller is composed of three rolls, it is necessary to prevent the rolls from interfering with each other. Therefore, there is an upper limit on the outer diameter of the roll. That is, when the roll mounting angle of the forming roller is α and the minimum outer diameter Rmin of the tapered portion of the tube after processing, the outer diameter D of the disk-type roll constituting the forming roller 1 is the following (2) It is necessary to satisfy the formula.
(3cos ² α + 1) ^0.5 / √3-cos α <Rmin / D (2) Equation (2) Equation (2) represents three outer diameters r ₀ of the tapered portion of the tube after processing. This is derived by obtaining the outer diameter d _{0 of the} rolls that cause the rolls to interfere with each other when spinning with a forming roller whose roll mounting angle is α.

In the following, when a forming tube composed of three rolls having an outer diameter d ₀ is used to spin an _element tube having an outer diameter r ₀ using a spinning machine with a roll attachment angle of the forming roller α, each roll A procedure for obtaining the outer diameter d ₀ of the roll when the two will interfere with each other will be described.

First, for the case of three mounting angle alpha = 0 ° of the roll, i.e., a case where the rotation center axis L ₁ of the three rolls of the forming roller is not inclined with respect to the rotational center axis L ₀ of the base pipe Consider the relationship between the outer diameter d ₀ of the roll and the outer diameter r _{0 of the} raw pipe when the rolls that are processing the raw pipe P interfere with each other.

FIG. 3 shows a case where circles A, B, and C drawn by three rolls (outer diameter d ₀ ) having the same outer diameter are placed on the same plane Pl _A around a circle O drawn by the raw tube (outer diameter r ₀ ). They are in contact with the circle O at P, Q, and R, respectively. Between the circles A, B and C drawn by the three rolls, planes Pl ₁ , Pl ₂ and Pl ₃ are shown perpendicular to the drawing, respectively. A regular triangle ΔABC connecting the centers A, B, and C of each roll is shown around the center O of the circle drawn by the raw tube. Since ΔABC is an equilateral triangle, ∠BAC = 60 °. Further, the lengths of the line segments OA, OB, OC connecting the center O of the raw tube and the centers A, B, C of each roll are all (r ₀ + d ₀ ) / 2.

ΔOAH and ΔODA are similar to each other, where H is an intermediate point of the line segment AB and D is a point where a vertical line drawn perpendicularly to the plane Pl ₂ from the center A of the circle intersects the plane Pl _1. Since the center angle ∠OAH of the circle A is δ ₀ , δ ₀ = ∠OAH = ∠ODA = ∠BAC / 2 = 30 °.

Therefore, δ ₀ is as follows for ΔOAH.
cos δ ₀ = AH / OA = d ₀ / (d ₀ + r ₀ ) = √3 / 2 Equation (3) Also, δ ₀ is as follows for ΔODA.
cos δ ₀ = DA / OD (4) Therefore, the ratio of the lengths of the line segments forming ΔODA is given by It becomes as follows.
OA: OD: DA = 1: 2: √3 Equation (5) Next, when this ΔODA is inclined by an angle α, ΔODA Consider the ratio of the lengths of the line segments that form

Figure 4 shows the positional relationship of the plane Pl _A and Pl ₁ when tilted plane Pl _A of the indicated △ ODA 3 by an angle alpha. Here, when the central angle ∠OAH after angle alpha inclined to [delta] _alpha, △ ratio of the length of the line segments forming the ODA has become as follows.
OA: OD: DA = cos ⁻¹ α: (cos ⁻² α + 3) ^0.5 : √3 (6) Therefore, δ _α when inclined by the angle _α is the following equation for ΔODA: It becomes as follows.
cos δ _α = DA / OD = √3 / (cos ⁻² α + 3) ^0.5 (7) Also, the outer diameter of the raw tube and the outer diameter of the roll after the inclination of the angle α are set to r _α and When d _alpha, is [delta] _alpha, for △ OAH, the following equation.
cosδ _α = OH / OA = d _α / (d _α + r _α ) (8) Then, in the three rolls of this forming roller, the plane Pl _A of ΔODA is inclined by an angle α. Is not at the center O of the tube but at the point P where the tube and the roll are in contact. Accordingly, the outer diameter d _{α of the} roll is the same as the outer diameter d ₀ when not inclined, but the outer diameter r _{α of the} raw tube is r ₀ cos ⁻¹ α. Therefore, δ _α is expressed by the following equation for ΔOAH: It becomes as follows.
cosδ _α = OH / OA = d ₀ / (d ₀ + r ₀ cos ⁻¹ α) Equation (9) Therefore, from the equations (7) and (9), if cosδ _α is eliminated,
d ₀ / (d ₀ + r ₀ cos ⁻¹ α) = √3 / (cos ⁻² α + 3) ^0.5 (10)

When this is transformed, the following equation is obtained.
r ₀ / d ₀ = (3 cos ² α + 1) ^0.5 / √3-cos α (11) Therefore, the roll mounting angle of the forming roller is α, and the minimum outer diameter of the tapered portion of the tube after processing In order to prevent the disk-type rolls constituting the forming roller 1 from interfering with each other when Rmin, it is necessary to make the roll diameter smaller than the roll diameter represented by the equation (7). It is necessary to satisfy equation (2).
(3cos ² α + 1) ^0.5 / √3−cosα <Rmin / D (2) Equation (2) Thus, by increasing the outer diameter of the roll, the amount of reduction is increased and spinning is performed. There was a limit to increasing the processing speed. Furthermore, although the molding roller consisting of three rolls is not as much as the molding roller consisting of two rolls, the cross section of the taper portion after processing is circular due to the occurrence of so-called “angularity” during spinning processing. In addition, there is a problem that polygons such as pentagons and octagons tend to be formed.

Figure 5 shows Kakubari during the spinning process is generated, the state in which the cross section of the tapered portion P ₂ after processing becomes octagonal. Incidentally, consider the degree of occurrence of "Kakubari" measures the cross-sectional shape of the tapered portion P ₂ after spinning, the cross section of the tapered portion P ₂ after the spinning process of the n-sided "polygon", the It can be evaluated by measuring the central angle θ. Hereinafter, this central angle θ is referred to as “angular angle”.

  The present invention solves the above-mentioned problem when using a spinning machine having a molding roller composed of three rolls when manufacturing a tapered pipe of various shapes by subjecting an element pipe to continuous diameter reduction by spinning. It is an object of the present invention to provide a method of manufacturing a tapered tube that can increase the processing speed of the spinning process and can suppress the occurrence of “angularity” during the spinning process. .

  As a result of various studies and experiments to solve the above problems, the present inventors have obtained the findings shown in the following (a) to (g).

  (a) When a spinning machine composed of two roll forming rollers is used, position control with the forming position roll becomes impossible. Therefore, it is necessary to process using a guide. Further, when spinning using a spinning machine composed of a two-roll molding roller, “squareness” is more likely to occur than when using a spinning machine composed of a three-roll molding roller.

  Therefore, it is preferable to use a spinning machine consisting of a three-roll molding roller, rather than using a spinning machine consisting of a two-roll molding roller, in that the guide need not be used.

  (b) In order to increase the processing speed without increasing the roll outer diameter of the spinning machine having a forming roller composed of three rolls, the amount of drawing by the forming roller may be increased.

  (c) As a method of increasing the drawing amount by the forming roller, it is conceivable to increase the number of rotations of the forming roller or increase the tensile speed of the raw tube.

  (d) “Square stretching” that occurs when spinning with a spinning machine having a molding roller consisting of three rolls occurs when the number of rotations of the molding roller is increased and when the tensile speed of the blank tube is increased. It can happen to either. Therefore, the occurrence of “squareness” cannot be suppressed only by defining the upper limit of the number of rotations of the forming roller and the upper limit of the tensile speed of the raw tube.

(e) Also, the roll outer diameter D of the forming roller composed of three rolls, the outer diameter R _{0 of the} raw pipe, and the maximum outer diameter Rmax and the minimum outer diameter Rmin of the tapered portion of the pipe were varied, It is not possible to sort out the presence or absence of “squareness” only by the magnitude of these numbers.

(f) However, when a forming roller composed of three rolls is subjected to spinning processing by setting the upper limit of the ratio Rmin / D of the minimum outer diameter Rmin of the tapered portion of the tube after processing to the outer diameter D of the roll to 0.3. , Occurrence of “angularity” regardless of the number of rotations of the forming roller, the tensile speed of the raw pipe, the roll outer diameter D, the outer diameter R _{0 of the} raw pipe and the maximum outer diameter Rmax and the minimum outer diameter Rmin of the tapered section of the pipe As described later, it was found by experiments that the suppression is suppressed.

As described above, since the forming roller is composed of three rolls, it is necessary to satisfy the formula (2) in order to prevent the rolls from interfering with each other. Accordingly, when the roll mounting angle of the forming roller is α, spinning is performed so that the minimum outer diameter Rmin of the tapered portion of the tube after processing and the roll outer diameter D of the forming roller satisfy the following expression (1). It only has to be processed.
(3cos ² α + 1) ^{0.5 /} √3-cos α <Rmin / D ≦ ^0.3 (1) where Rmax = 75.0 mm, Rmin = 60.5 mm, tube thickness = 4.2 mm , An adapter at the tip of the illumination column having a taper portion of L = 25 mm is attached with the rotation center axis L ₁ of the three rolls at an attachment angle α with respect to the rotation center axis L _{0 of the} base tube P ₀ . The numerical value on the left side of the above equation (1) when machining using a spinning machine will be exemplified.
It is 0.155 when α = 0 °, 0.175 when α = 30 °, 0.206 when α = 45 °, and 0.264 when α = 60 °.

  Therefore, from the viewpoint of suppressing the occurrence of “angularity”, it is understood that the smaller the mounting angle α, the larger the allowable range of the ratio Rmin / D of the minimum outer diameter Rmin of the tapered portion of the pipe to the roll outer diameter D.

  (g) As described above, the degree of occurrence of “angularity” is considered to be that the section of the tapered portion after spinning is regarded as an n-polygon, and its central angle θ, that is, “angular angle” Can be evaluated by measuring. “Square tension” is acceptable when the cross-sectional shape of the tapered portion after spinning is n ≧ 36, that is, when the cornering angle θ ≦ 10 °, it is assumed to be a substantially perfect circle.

  The present invention has been made based on the above findings, and the gist thereof is the following (1) and (2) taper tube manufacturing methods.

(1) A forming roller consisting of three rolls is arranged on the outer periphery of the raw pipe, and the forming roller is moved forward and backward in the pipe radial direction with respect to the rotating raw pipe, and the forming roller and the raw pipe are moved in the pipe axis direction. A taper tube manufacturing method using a spinning method for continuously reducing the diameter of a raw tube by a synthetic movement obtained by relative movement, and when the roll mounting angle of the forming roller is α, A method of manufacturing a tapered tube, characterized by subjecting the raw tube to continuous diameter reduction so that the minimum outer diameter Rmin of the tapered portion of the tube and the roll outer diameter D of the forming roller satisfy the following equation (1): .
(3cos ² α + 1) ^{0.5 /} √3-cos α <Rmin / D ≦ ^0.3 (1)
(2) Eliminating the spiral linear marks by providing a pressing roller after the forming roller and pressing the outer surface of the pressing roller against the spiral linear marks formed on the tube surface by the forming roller. (1) The method for producing a tapered tube according to (1) above.

  (3) In the method for manufacturing a tapered tube of the above (1) or (2), the taper portion has a maximum outer diameter Rmax = 75 to 120 mm, a taper portion has a minimum outer diameter Rmin = 55 to 100 mm, and a tube thickness = 3.2. 6. A method of manufacturing a tapered tube, comprising manufacturing a tapered tube having a length of 6.0 mm and a tube length L of the tapered portion of 10 to 45 mm.

  According to the method for manufacturing a tapered tube according to the present invention, when manufacturing a tapered tube having various shapes using a spinning machine having a molding roller composed of three rolls, even if the processing speed of the spinning process is increased. The occurrence of “squareness” can be suppressed.

  Hereinafter, the manufacturing method of the taper pipe | tube which concerns on this invention is demonstrated concretely.

As described above, FIG. 2 is an example of a stepped tube. This stepped pipe has a taper portion P ₁ having a tube length L that gradually changes from a maximum outer diameter Rmax to a minimum outer diameter Rmin, a straight portion P ₁ that is continuous on both sides thereof, and has a constant outer diameter Rmax and an outer portion. diameter is from certain of the straight portion P ₃ at Rmin. The straight portion P ₁ may be a raw pipe having an outer diameter of Rmax without being processed, or the raw pipe is straight processed by a forming roller using the above-described spinning processing machine, and a circle having an outer diameter of Rmax is obtained. It may be formed into a tube. The taper portion P ₂ continuing to the straight portion P ₁ can be tapered by changing the gradient by moving the forming roller more than usual (reducing diameter movement). The gradient of the tapered portion P ₂ is advanced moving speed of the forming roller by adjusting the moving speed of the (reduced径速degree) or blank pipe P _0, it can be variously changed. After tapered until the outer diameter of the tapered portion P ₂ in Rmin by returning straight machining, the straight portion P ₃ of the outer diameter Rmin continuous to the tapered portion P ₂ can be continuously molded.

  In addition, when a spiral linear mark is formed on the tube surface by the forming roller, the spiral roller formed on the tube surface by driving the roll of the pressing roller provided at the subsequent stage of the forming roller. By pressing against the linear traces, the spiral linear traces can be erased.

  Thus, a stepped tube can be manufactured by spinning. And the rotation speed of the shaping | molding roller at the time of manufacturing the stepped pipe | tube used for the adapter of the dimension mentioned above by a spinning process is about 300-550 rpm, and the tensile speed of a pipe | tube is about 600-900 mm / min. In terms of the amount of movement of the tube, it is 3.00 to 9.00 mm per rotation of the forming roller. Further, the number of molding drawing may be one-pass molding, but it is preferable to employ multi-pass molding of about four times.

  Further, the adapter is not limited to the tapered pipe having such a shape, and other various shaped tapered pipes may be used. Moreover, the taper tube manufactured by this invention is applicable not only to an adapter but other uses.

If a spinning machine with three rolls of forming roller 1 is used, “squareness” occurs, and the cross section of the tapered portion after processing does not become circular, but a polygon such as a pentagon or an octagon. As described above, there are cases in which Therefore, in order to suppress the occurrence of angularity, when the roll mounting angle of the forming roller is α, the minimum outer diameter Rmin of the tapered portion of the tube after processing and the roll outer diameter D of the forming roller are the following ( In order to satisfy the formula (1), it is necessary to continuously reduce the diameter of the raw pipe.
(3cos ² α + 1) ^{0.5 /} √3−cos α <Rmin / D ≦ ^0.3 (1) Formula In the following, according to Examples 1 and 2, the above formula (1) is satisfied and continuous to the raw tube It shows that the occurrence of angulation can be suppressed by reducing the diameter. Next, even in the case of manufacturing a stepped tube used as an adapter for an illumination column according to Example 3, if the above-mentioned equation (1) is satisfied and the diameter of the base tube is continuously reduced, the occurrence of angularity is suppressed. Show what you can do.

  As shown in Experiment No. A of Table 1, various tapered tubes with tapered portions having a maximum outer diameter Rmax = 165.2 mm, a minimum outer diameter Rmin = 75.0 to 140.0 mm, and a tube thickness = 4.2 mm are shown in FIG. Using the spinning machine shown in No. 1, the taper part was produced at a molding roller rotation number of 350 rpm and a tube tensile speed of 700 mm / min. At this time, the driving roll of the forming roller of the spinning machine was one having an outer diameter D of 355 mm. Then, the angular angle θ of the cross section of the tapered portion of the obtained tapered tube was measured.

  In addition, as shown in Experiment No. B in Table 1, the taper portion has various taper tubes having a maximum outer diameter Rmax = 177.8 mm, a minimum outer diameter Rmin = 75.0 to 145.5 mm, and a tube thickness = 4.2 mm. Using the spinning machine shown in FIG. 1, the taper part was formed at a rotation speed of the forming roller of 450 rpm and a tube pulling speed of 700 mm / min. At this time, the driving roll of the forming roller of the spinning machine was one having an outer diameter D of 355 mm. Then, the angular angle θ of the cross section of the tapered portion of the obtained tapered tube was measured.

  FIG. 6 shows the ratio Rmin / D of the minimum outer diameter Rmin of the tube tapered portion after processing to the roll outer diameter D of the forming roller for the angular angle θ measured for the section of the tapered portion for the experiment numbers A and B. Are organized in

  Regardless of the number of rotations of the forming roller and the pulling speed of the tube, when Rmin / D is 0.3 or less, the angular angle θ is 10 ° or less, but when Rmin / D exceeds 0.3, It can be seen that the angular angle θ increases rapidly and exceeds an allowable 10 °.

  As shown in Experiment No. C of Table 2, various tapered pipes having a taper portion with a maximum outer diameter Rmax = 165.2 mm, a minimum outer diameter Rmin = 60.5 to 140.0 mm, and a pipe thickness = 4.2 mm are illustrated. Using the spinning machine shown in No. 1, the taper part was produced at a molding roller rotation number of 350 rpm and a tube tensile speed of 700 mm / min. At this time, the driving roll of the forming roller of the spinning machine was one having an outer diameter D of 225 mm. Then, the angular angle θ of the cross section of the tapered portion of the obtained tapered tube was measured.

  In addition, as shown in Experiment No. D in Table 2, the taper portion has various taper tubes having a maximum outer diameter Rmax = 177.8 mm, a minimum outer diameter Rmin = 60.5 to 140.0 mm, and a tube thickness = 4.2 mm. Using the spinning machine shown in FIG. 1, the taper part was formed at a rotation speed of the forming roller of 450 rpm and a tube pulling speed of 700 mm / min. At this time, the driving roll of the forming roller of the spinning machine was one having an outer diameter D of 225 mm. Then, the angular angle θ of the cross section of the tapered portion of the obtained tapered tube was measured.

  FIG. 7 shows the ratio Rmin / D of the minimum outer diameter Rmin of the tube tapered portion after processing to the roll outer diameter D of the forming roller, for the experiment numbers C and D. Are organized in

  Regardless of the number of rotations of the forming roller and the pulling speed of the tube, when Rmin / D is 0.3 or less, the angular angle θ is 10 ° or less, but when Rmin / D exceeds 0.3, It can be seen that the angular angle θ increases rapidly and exceeds an allowable 10 °.

  The step shown in Table 3 was conducted using a spinning machine shown in FIG. 1 with a stepped tube having a taper portion with a maximum outer diameter Rmax = 75.0 mm, a minimum outer diameter Rmin = 60.5 mm, and a tube thickness = 4.2 mm. The adapter of L = 25 mm was manufactured by changing the roll outer diameter D and the number of rotations of the forming roller and the tensile speed of the tube under the conditions indicated by the numbers E to I, and forming the tapered portion. And the squareness angle (theta) of the cross section of the taper part of the obtained adapter was measured.

  FIG. 8 shows a ratio Rmin / D of the minimum outer diameter Rmin of the tube tapered portion after processing to the roll outer diameter D of the forming roller, with respect to the experiment number E to I, with the measured angular angle θ of the section of the tapered portion. Are organized in

  Regardless of the number of rotations of the forming roller and the pulling speed of the tube, when Rmin / D is 0.3 or less, the angular angle θ is 10 ° or less, but when Rmin / D exceeds 0.3, It can be seen that the angular angle θ of the cross section of the taper portion of the obtained adapter suddenly increases and exceeds an allowable 10 °.

  According to the method for manufacturing a tapered tube according to the present invention, when manufacturing a tapered tube having various shapes using a spinning machine having a molding roller composed of three rolls, even if the processing speed of the spinning process is increased. The occurrence of “squareness” can be suppressed.

An example (side view) of the spinning machine used when manufacturing a taper pipe by spinning is shown. It is an example of a stepped pipe. Around the base tube P (outer diameter r ₀ ), three rolls (outer diameter d ₀ ) having the same outer diameter are in contact with each other at P, Q, R, and the rolls are also in contact with each other. Indicates that Around a P shown in FIG. 3, showing the positional relationship of the plane Pl _A and Pl ₁ when tilted plane Pl _A by attachment angle α of the roll. Kakubari during the spinning process is generated, showing a state in which the cross section of the tapered portion P ₂ after processing becomes octagonal. For Experiment Nos. A and B, the measured angular angle θ of the cross section of the tapered portion is arranged by the ratio Rmin / D of the minimum outer diameter Rmin of the tapered portion of the tube after processing to the roll outer diameter D of the forming roller. It is. For Experiment Nos. C and D, the measured angular angle θ of the cross section of the tapered portion is arranged by the ratio Rmin / D of the minimum outer diameter Rmin of the tapered portion of the tube after processing to the roll outer diameter D of the forming roller. It is. For Experiment Nos. E to I, the measured squareness angle θ of the cross section of the tapered portion is arranged by the ratio Rmin / D of the minimum outer diameter Rmin of the tapered portion of the tube after processing to the roll outer diameter D of the forming roller. It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Forming roller 2 Heating device 3 Support roller 4 Pulling cart 5 Pressing roller D Rolling outer diameter of forming roller L Tube length of taper part L ₀ Rotation center axis of _element tube L ₁ Roll rotation center axis of element roller P ₀ Element tube P ₁ Straight part P ₂ Taper part P ₃ Straight part R ₀ Outer diameter of raw tube Rmax Maximum outer diameter of taper part Rmin Minimum outer diameter of taper part α Rolling angle of forming roller θ Angular angle

Claims (3)

A forming roller consisting of three rolls is arranged on the outer periphery of the raw tube, and the forming roller is moved forward and backward in the radial direction of the tube with respect to the rotating raw tube, and the forming roller and the raw tube are moved relative to each other in the tube axis direction. A taper tube manufacturing method using a spinning method for continuously reducing the diameter of a raw tube by a composite movement obtained when the roll mounting angle of the forming roller is α, the tube taper after processing A method for producing a tapered tube, comprising subjecting the raw tube to continuous diameter reduction so that the minimum outer diameter Rmin of the portion and the roll outer diameter D of the forming roller satisfy the following expression (1):
(3cos ² α + 1) ^{0.5 /} √3-cos α <Rmin / D ≦ ^0.3 (1)   A pressing roller is provided after the molding roller, and the spiral linear trace is erased by pressing the outer peripheral surface of the pressing roller against the spiral linear trace formed on the tube surface by the molding roller. The method for manufacturing a tapered tube according to claim 1. 3. The method for manufacturing a tapered tube according to claim 1, wherein the taper portion has a maximum outer diameter Rmax = 75 to 120 mm, a taper portion has a minimum outer diameter Rmin = 55 to 100 mm, a tube thickness = 3.2 to 6.0 mm, and the taper portion. A taper tube having a tube length L = 10 to 45 mm is manufactured.

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