JP2018114537A - Mandrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform bending processing of a steel pipe with good accuracy and improve processing efficiency.SOLUTION: A mandrel comprises: a first intermediate member on which a tip member on which a spherical surface is formed, the spherical surface, a curved concave surface which contacts the spherical surface of the tip member, and a tapered opening which is widened toward the spherical surface from the curved concave surface are formed; a base having a curved concave surface which contacts the spherical surface of the first intermediate member; and a connection member which penetrates through the opening of the intermediate member, one end of which is fixed to the tip member, and the other end is fixed to the base.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a mandrel.

  For example, a mandrel is used for bending a steel pipe used for gas or liquid piping or manufacturing a steel pipe joint. The mandrel is composed of a plurality of parts connected to each other (see, for example, Patent Documents 1 and 2). This type of mandrel has a limited working area between the parts, and the entire mandrel is curved so as to draw an arc of a predetermined radius.

  When the steel pipe into which the mandrel is inserted is bent, wrinkles and irregularities are likely to occur inside the steel pipe. Therefore, it is preferable that the gap between the parts constituting the mandrel is kept small to some extent regardless of the degree of curvature of the mandrel.

JP-A-11-179437 JP 2005007437 A

  In the mandrels disclosed in Patent Documents 1 and 2, a gap is formed between the parts even when the mandrel is stretched and straight. For this reason, it is considered that wrinkles occur when the steel pipe is bent.

  Further, when the mandrel is curved, the gap between the parts on the inner side of the curve is narrowed, but the gap between the parts on the outer side of the curve is widened. For this reason, it is conceivable that the resistance when the mandrel is pulled out from the bent steel pipe is increased. In such a case, the bending efficiency may be reduced.

  This invention is made | formed under the above-mentioned situation, and makes it a subject to improve processing efficiency while performing the bending process of a steel pipe accurately.

  In order to solve the above problems, a mandrel according to the present embodiment includes a tip member formed with a spherical surface, a spherical surface, a curved concave surface in contact with the spherical surface of the tip member, and a taper that extends from the curved concave surface toward the spherical surface. A first intermediate member formed with an opening having a shape, a base having a curved concave surface in contact with the spherical surface of the first intermediate member, and one end fixed to the tip member through the opening of the intermediate member And a connecting member having the other end fixed to the base.

  The tip member may be formed with a tapered opening that penetrates the connecting member and extends toward the spherical surface.

  The mandrel includes a second intermediate member formed with a spherical surface, a curved concave surface in contact with the spherical surface of the first intermediate member, and a tapered opening extending from the curved concave surface toward the spherical surface. Also good.

  The curvature of the spherical surface of the tip member, the curvature of the spherical surface and the curved concave surface of the intermediate member, and the curvature of the curved concave surface of the base may be equal to each other.

  The outer surface of the intermediate member may be composed of only the spherical surface and the curved concave surface.

  The connecting member may be a coil spring. Further, the connecting member may be a wire.

  In the mandrel according to the present invention, no gap is formed between the members constituting the mandrel before and after bending. For this reason, while bending a steel pipe accurately, processing efficiency can be improved.

It is a side view of the mandrel concerning this embodiment. It is sectional drawing which shows the XZ cross section of a mandrel. It is a perspective view of a ball member. It is a perspective view of an intermediate member. It is a perspective view of a base. It is a figure for demonstrating operation | movement of a mandrel. It is a figure for demonstrating the bending process of a steel pipe. It is a figure for demonstrating the bending process of a steel pipe. It is a figure which shows the modification of a mandrel. It is a figure which shows the modification of a mandrel.

  Hereinafter, the mandrel according to the present embodiment will be described with reference to the drawings. In the description, an XYZ coordinate system including an X axis, a Y axis, and a Z axis that are orthogonal to each other is used as appropriate.

FIG. 1 is a side view of a mandrel 10 according to the present embodiment. FIG. 2 is a cross-sectional view showing the XZ cross section of the mandrel 10. The mandrel 10 is a tool for bending a steel pipe made of a metal such as iron, stainless steel, or aluminum. 1 and 2
As shown in FIG. 1, the mandrel 10 includes a ball member 20, four intermediate members 30, a base 40, and a coil spring 50. The ball member 20, the intermediate member 30, and the base 40 are made of, for example, iron or stainless steel.

  FIG. 3 is a perspective view of the ball member 20. The ball member 20 is a spherical member having a diameter of about 8 cm, for example. As shown in FIG. 3, the ball member 20 has an opening 21 extending from the upper side (+ Z side) to the center and an opening 23 extending from the lower side (−Z side) to the center. The inner diameter of the opening 21 is constant, and an internal thread portion is formed on the inner peripheral surface. Further, the opening 23 is shaped into a tapered shape having an inner diameter that increases from the center of the ball member 20 to the outer peripheral surface.

  The central axis of the opening 21 and the central axis of the opening 23 are parallel to the Z axis and coincide with each other. Therefore, the opening 21 and the opening 23 form a through hole that penetrates the ball member 20. An annular protrusion 22 is formed on the surface of the ball member 20 so as to surround the opening 21.

  FIG. 4 is a perspective view of the intermediate member 30. The intermediate member 30 is a member having an outer diameter of about 8 cm centered on the Z axis. As shown in FIG. 4, the intermediate member 30 is shaped so that the upper side (+ Z side) is a curved concave surface 31 and the lower side (−Z side) is a spherical surface 32. The curvature of the spherical surface 32 and the curvature of the curved concave surface 31 of the intermediate member 30 are equal to the curvature of the outer surface of the ball member 20. The intermediate member 30 has an opening 33 extending from the center of the curved concave surface 31 to the center of the spherical surface 32. The opening 33 is shaped into a tapered shape having an inner diameter that increases from the curved concave surface 31 to the spherical surface 32.

  FIG. 5 is a perspective view of the base 40. As shown in FIG. 5, the base 40 is a member whose longitudinal direction is the Z-axis direction and whose outer shape is about 8 cm. A curved concave surface 41 is formed on the upper surface of the base 40, and an opening 42 whose longitudinal direction is the Z-axis direction is formed at the center of the curved concave surface 41.

  The curvature of the curved concave surface 41 is equal to the curvature of the spherical surface 32 of the intermediate member 30. The inner diameter of the opening 42 is constant, and an internal thread portion is formed on the inner peripheral surface. Further, the lower portion of the base 40 is shaped into a tapered shape whose outer shape becomes narrower downward. An opening 43 having a longitudinal direction in the Z-axis direction is formed at the center of the lower surface of the base 40. The inner diameter of the opening 43 is constant, and an internal thread portion is formed on the inner peripheral surface.

  As shown in FIG. 2, in the mandrel 10, four intermediate members 30 that overlap each other are disposed on the curved concave surface 41 of the base 40, and the ball member 20 is disposed on the curved concave surface 31 of the intermediate member 30 that is positioned on the top. Is placed.

  The coil spring 50 is a tension spring extending from a natural length. The coil spring 50 passes through the opening 23 of the ball member 20 and the openings 33 of the four intermediate members 30 disposed between the bases 40. The upper end of the coil spring 50 is fixed to the ball member 20 via a fixing member 51 that fits into the female screw portion of the opening 21 provided in the ball member 20. Further, the lower end of the coil spring 50 is fixed to the base 40 via a fixing member 52 that fits into the female thread portion of the opening 42 provided in the base 40. The ball member 20, the four intermediate members 30, and the base 40 are integrated by being fixed to the ball member 20 and the base 40 with the coil spring 50 penetrating the four intermediate members 30.

The tension of the coil spring 50 is determined by rotating the fixing member 51 relative to the ball member 20, or rotating the fixing member 52 relative to the base 40 to determine the distance between the fixing member 51 and the fixing member 52. It can be adjusted by changing. The tension of the coil spring 50 is adjusted so that the ball member 20, the intermediate member 30, and the base 40 are not separated from each other.

  In the mandrel 10 configured as described above, as shown in FIG. 2, the base 40 and the intermediate member 30 are in a state in which the spherical surface 32 of the intermediate member 30 is slidably in contact with the curved concave surface 41 of the base 40. Be placed. Therefore, the intermediate member 30 can rotate at least about an axis parallel to the XY plane with respect to the base 40. Similarly, the intermediate members 30 adjacent to each other are arranged in a state in which the spherical surface 32 of the other intermediate member 30 is slidably in contact with the curved concave surface 31 of the intermediate member 30. Accordingly, one adjacent intermediate member 30 is rotatable relative to the other intermediate member 30 at least about an axis parallel to the XY plane. Further, the intermediate member 30 and the ball member 20 are disposed in a state where the outer surface of the ball member 20 is slidably in contact with the curved concave surface 31 of the intermediate member 30. Therefore, the ball member 20 is rotatable relative to the intermediate member 30 at least about an axis parallel to the XY plane. Therefore, the mandrel 10 can be curved as shown in FIG. 6 as an example.

  Further, even if each component of the mandrel 10 rotates, the positional relationship between the ball member 20, the intermediate member 30, and the base 40 is maintained constant by the spherical surface and the curved concave surface that contacts the spherical surface. For this reason, no gap is formed between the constituent parts.

  In the mandrel 10 according to this embodiment, the ball member 20 rotates more than 90 degrees with respect to the base 40. When the ball member 20 is rotated 90 degrees with respect to the base 40, the four intermediate members 30 are rotated about 18 degrees, 36 degrees, 54 degrees, and 62 degrees with respect to the base 40, respectively.

  The mandrel 10 is curved to the extent that the openings 21 and 23 of the ball member 20, the opening 33 of the intermediate member 30, and the opening 42 of the base 40 communicate with each other and a space for the coil spring 50 is secured. It is possible to do.

  Next, the bending process of the steel pipe 100 using the mandrel 10 will be described. First, a steel pipe 100 to be bent is prepared. The steel pipe 100 has a slightly larger inner diameter than the outer diameters of the ball member 20, the intermediate member 30, and the base 40 constituting the mandrel 10. When bending the steel pipe 100, first, the mandrel 10 is inserted into the steel pipe 100 as shown in FIG. When inserting the mandrel 10 into the steel pipe 100, for example, by attaching an external device or jig to the opening 43 provided in the base 40 of the mandrel 10, even if the steel pipe 100 is long, the mandrel 10 can be inserted deep inside.

  When the mandrel 10 is inserted to the place where the steel pipe 100 is bent, the steel pipe 100 is bent together with the mandrel 10 as shown in FIG. When the steel pipe 100 is bent, the steel pipe 100 may be heated as necessary. As shown in FIG. 8, even if the mandrel 10 is bent to 90 degrees, no gap is formed between the ball member 20, the intermediate member 30, and the base 40. For this reason, the frequency of occurrence of wrinkles generated when the steel pipe 100 is bent can be reduced.

  When the steel pipe 100 is bent to a target angle of 90 degrees, for example, the mandrel 10 is pulled out from the steel pipe 100. Thereby, the bending process of the steel pipe 100 is complete | finished.

  As described above, in the mandrel 10 according to the present embodiment, even if the mandrel 10 is curved, the positional relationship between the ball member 20, the intermediate member 30, and the base 40 is the components of the mandrel 10 (20, 30, 40). And a curved concave surface in contact with the spherical surface. For this reason, no gap is formed between the constituent parts. Therefore, the bending of the steel pipe can be performed with high accuracy.

  Further, when the mandrel 10 is inserted into the steel pipe 100 or when the mandrel 10 is pulled out from the steel pipe 100, the influence of the frictional force generated between the steel pipe 100 and the mandrel 10 is affected. The outer surfaces of the ball member 20, the intermediate member 30, and the base 40 constituting the mandrel 10 according to the present embodiment are spherical. Therefore, the frictional force generated between the steel pipe 100 and the mandrel 10 is reduced. Therefore, it becomes possible to perform the bending process of the steel pipe 100 efficiently.

  As mentioned above, although embodiment of this invention was described, this invention is not limited by the said embodiment. For example, in the above embodiment, the case where the ball member 20, the intermediate member 30, and the base 40 configuring the mandrel 10 are integrated by the coil spring 50 has been described. For example, as shown in FIG. 9, the ball member 20, the intermediate member 30, and the base 40 may be integrated using a wire 55 instead of the coil spring 50.

  In this case as well, the tension of the wire 55 can be adjusted by rotating the fixing members 51 and 52 to which the ends of the wire 55 are fixed relative to the ball member 20 or the base 40. .

  In the above embodiment, as shown in FIG. 2, the case where the mandrel 10 includes the four intermediate members 30 has been described. Not limited to this, the mandrel 10 may include three or less intermediate members 30 or three or less.

  In the above embodiment, the case where the outer diameter of the mandrel 10 is about 8 cm has been described. Not only this but the outer diameter and length of the mandrel 10 can be suitably changed according to the size of the steel pipe used as the object of bending.

  In the above embodiment, the case where the entire outer surfaces of the ball member 20 and the intermediate member 30 are spherical has been described. Not only this but the outer surface of the ball member 20 and the intermediate member 30 is good also as only the surface which touches the other intermediate member 30 or the base 40 being a spherical surface.

  In the above embodiment, the case where the coil spring 50 and the wire 55 are fixed to the ball member 20 in a state where the coil spring 50 and the wire 55 penetrate the opening 23 of the ball member 20 has been described. The present invention is not limited to this, and one end of a coil spring 50 or the like may be directly fixed to the ball member 20 as shown in FIG.

  As mentioned above, although embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 10 Mandrel 20 Ball member 21, 23 Opening part 22 Protrusion part 30 Intermediate member 31 Curved concave surface 32 Spherical surface 33 Opening part 40 Base 41 Curved concave surface 42,43 Opening part 50 Coil spring 51,52 Fixing member 55 Wire 100 Steel pipe

Claims (7)

A tip member on which a spherical surface is formed;
A first intermediate member formed with a spherical surface, a curved concave surface in contact with the spherical surface of the tip member, and a tapered opening extending from the curved concave surface toward the spherical surface;
A base having a curved concave surface in contact with the spherical surface of the first intermediate member;
A connecting member that penetrates through the opening of the intermediate member and has one end fixed to the tip member and the other end fixed to the base;
Mandrel with   2. The mandrel according to claim 1, wherein the tip member is formed with a tapered opening through which the connecting member passes and expands toward the spherical surface.   3. A second intermediate member formed with a spherical surface, a curved concave surface in contact with the spherical surface of the first intermediate member, and a tapered opening extending from the curved concave surface toward the spherical surface. The mandrel described in   The mandrel according to any one of claims 1 to 3, wherein the curvature of the spherical surface of the tip member, the curvature of the spherical surface of the intermediate member and the curved concave surface, and the curvature of the curved concave surface of the base are equal.   The mandrel according to any one of claims 1 to 4, wherein an outer surface of the intermediate member includes only the spherical surface and the curved concave surface.   The mandrel according to any one of claims 1 to 5, wherein the connecting member is a coil spring.   The mandrel according to any one of claims 1 to 5, wherein the connecting member is a wire.

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