JP2011196142A - Beam mounting structure of guard fence - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a beam mounting structure of a guard fence that can be installed using the same fitting for a slope and a curve point.SOLUTION: A first bolt hole 22 is formed with lateral guide grooves 23 laterally, and stop holes 24 are formed on the vertical sides of each guide groove 23. A second bolt hole 32 is formed as a cross-shaped hole comprising a vertically long hole part 321 and a laterally long hole part 322, and protrusions 33 are formed at the edge 323 of the laterally long hole part 322. When a beam B is laterally adjusted to a post 1, the protrusions 33 are inserted in the guide grooves 23 of a base fitting 2 and moved along the guide grooves 23. When the beam B is vertically inclined with respect to the post 1, the protrusions 33 can be inserted into the stop holes 24 of the base fitting 2. The guard fence can thereby be efficiently and surely installed using the same fitting even on a slope or a curve point.

Description

  The present invention relates to a beam mounting structure for a protective fence such as a panel fence, a beam fence, or a mesh fence fence installed on a road or the like.

  Conventionally, as a beam mounting structure of a guard fence installed on a road or the like, for example, in a beam mounting structure of a guard fence where a beam is mounted on a side surface of a support column, it is mounted on a base bracket and a beam end that are in contact with the side surface of the column. A beam holding bracket, the outer surface of the base bracket is a cylindrical shape that is curved in the vertical direction, and the center of curvature of the cylinder is a joint that coincides with the center of the column, and the tip of the beam holding bracket is A beam mounting structure for a protective fence, which is formed in a bowl shape corresponding to the joint surface of the base metal fitting, and the beam is attached to the column by pressing and screwing the tip of the beam holding metal fitting to the joint surface of the base metal fitting Has been proposed. (Patent Document 1)

JP 09-125328 A

  However, the beam mounting structure of the guard fence is effective on an inclined installation surface, but on the installation surface where the road is curved, the beam cannot be adjusted in the horizontal direction. It was necessary to have a variety of mounting brackets.

  Therefore, the present invention provides a beam mounting structure for a protective fence that can be installed using the same mounting bracket even on an inclined installation surface or at a curved point where the beam needs to be adjusted in the horizontal direction. To do.

In order to achieve the above object, the present invention is configured as follows.
That is, the protective fence beam mounting structure according to the present invention is:
A base bracket disposed on the support column side and a beam support bracket disposed on the outer side of the base bracket to support the beam. The base bracket and the beam support bracket are provided on either one of the hemispherical protrusions. And a first bolt hole provided in communication with the two mounting surfaces and a second bolt surface are disposed opposite to the hemispherical concave second mounting surface provided on the other side. The first bolt hole provided in the mounting surface is attached to at least one of the left and right sides of the first bolt hole that is attached to the support pillar through the bracket mounting bolt inserted into the bolt hole. Direction guide grooves are formed, stopper holes are formed above and below the guide grooves, and the second bolt hole is a cross-shaped hole composed of a vertically long hole portion and a horizontally long hole portion, and the horizontally long A protrusion is formed on the edge of the hole or on its extension. When adjusting the beam in the horizontal direction with respect to the column, the protrusion is inserted into the guide groove of the base metal fitting, moved along the guide groove, and tilted in the vertical direction with respect to the column. Is characterized in that the protrusion can be inserted into the retaining hole of the base metal fitting.

  Further, the beam mounting structure of the guard fence according to the present invention has the hemispherical convex first mounting surface provided on the base metal fitting and the hemispherical concave second mounting surface provided on the base end of the beam support metal fitting. The mounting wall is provided on the column side, and the beam side surface of the mounting wall is a hemispherical convex surface.

  Also, the beam mounting structure of the guard fence according to the present invention is characterized in that the beam support bracket includes a beam receiving bracket that receives a beam end portion and a covering bracket that covers the beam end portion and covers the beam end portion. The beam receiving bracket is provided with a mounting surface disposed opposite to the mounting surface provided on the bracket.

  Further, the beam mounting structure of the guard fence according to the present invention has a beam receiving portion projecting outward from the mounting wall of the beam receiving bracket, and a longitudinal wall in the longitudinal direction at both side ends of the beam receiving portion. And the mounting wall side of the vertical wall is notched to form a notch, while the notch is located at a position corresponding to the notch of the covering metal fitting on the beam receiving metal fitting. A protruding wall to be fitted is formed.

  Further, the beam mounting structure of the guard fence according to the present invention includes a beam fixing bolt for fixing the beam receiving bracket, the covering bracket and the beam through the vertical wall of the beam receiving bracket and the side surface portion of the covering bracket. And a through hole for inserting a cylindrical nut to be screwed into the beam fixing bolt, and the through hole has a depth that does not project the flange-shaped head formed on the beam fixing bolt and nut. And a polygonal portion corresponding to a polygonal lower neck formed under the head of one of the beam fixing bolt and nut. It is.

  According to the beam mounting structure of the guard fence according to the present invention, the base bracket includes a base bracket disposed on the support column side, and a beam support bracket disposed outside the base bracket to support the beam. The support metal fitting has a hemispherical convex first mounting surface provided on either side opposed to a hemispherical concave second mounting surface provided on the other side, and on both the mounting surfaces. A bracket mounting bolt inserted into the first bolt hole and the second bolt hole provided in communication with each other is penetrated through the mounting hole of the column, is attached to the column, and is provided on the mounting surface. The bolt hole is formed with a lateral guide groove on at least one of the left and right sides thereof, and a stop hole is formed above and below the guide groove. Further, the second bolt hole has a vertically long hole portion and a horizontally long hole. And a cross-shaped hole made of a portion, A protrusion is formed on the edge of the long hole portion or an extension thereof. When adjusting the beam in the left-right direction with respect to the support column, the protrusion is inserted into the guide groove of the base metal fitting, and along the guide groove. When the beam is moved and tilted in the vertical direction with respect to the support column, the projection can be inserted into the retaining hole of the base metal fitting. Whether the protective fence is adjusted and installed, or the beam is adjusted in the vertical direction such as on an inclined ground, the protective fence can be installed efficiently and reliably using the same metal fittings.

  Further, according to the beam mounting structure of the guard fence according to the present invention, the hemispherical convex first mounting surface is provided on the base metal fitting, and the hemispherical concave second mounting surface is provided on the base end of the beam supporting metal fitting. Since the mounting wall is provided on the column side surface and the beam side surface of the mounting wall is a hemispherical convex surface, the base metal fitting and the beam support metal fitting can be adjusted smoothly.

  Further, according to the beam mounting structure of the guard fence according to the present invention, the beam support bracket includes a beam receiving bracket that receives the beam end portion and a covering bracket that covers the beam end portion and covers the beam end portion, Since the mounting surface facing the mounting surface provided on the base bracket is provided on the beam bracket, the beam can be beamed by aligning the mounting surfaces of the base bracket and the beam bracket and fixing them with the bracket mounting bolts. Temporary placement on the metal fitting can be performed, and workability can be improved.

  Further, according to the beam mounting structure of the guard fence according to the present invention, the beam receiving portion protrudes outward from the mounting wall of the beam receiving bracket, and the beam receiving portion is vertically extended on both side ends of the beam receiving portion. While the wall is erected, the mounting wall side of the vertical wall is notched to form a notch portion, while the notch portion is located at a position corresponding to the notch portion of the covering metal fitting on the beam receiving metal fitting. Since a projecting wall that fits in is formed, use a tightening tool such as a spanner to tighten the bolt head or nut with a tightening tool in order to fix the base bracket and beam bracket with the bracket mounting bolt. At this time, since the stroke of the tightening tool can be secured without being obstructed by the vertical wall of the beam receiving portion, the workability can be improved.

  Further, according to the beam mounting structure of the protective fence according to the present invention, the beam fixing bracket for fixing the beam receiving bracket, the covering bracket and the beam through the vertical wall of the beam receiving bracket and the side surface portion of the covering bracket. A through hole for inserting a bolt and a cylindrical nut to be screwed into the beam fixing bolt is formed, and the through hole has a depth that does not protrude the flange-shaped head formed on the beam fixing bolt and the nut. Since the countersink part is formed, and the polygonal part corresponding to the polygonal neck lower part formed below the head of either the beam fixing bolt or nut is formed, the beam surface is The beam fixing bolt head or nut does not protrude, which is preferable in appearance. In addition to preventing injury from being hit by a human hand, the beam fixing bolt or nut is tightened. When attaching, the lower part of the neck and the polygonal part are in contact with each other, so it is not necessary to hold either the beam fixing bolt or the nut. be able to.

It is a front view which shows one Embodiment of the beam attachment structure of the protection fence which concerns on this invention. It is explanatory drawing which shows the attachment method of the beam attachment structure of the guard fence shown in FIG. 2A is a perspective view of a base metal fitting, and FIG. 2B is a perspective view showing a beam receiving metal fitting used in the beam mounting structure of the guard fence shown in FIG. 2A is a front view showing an outer surface of a base metal fitting, and FIG. 2B is a front view showing a concave curved surface of a beam receiving metal fitting used in the beam mounting structure of the guard fence shown in FIG. It is a perspective view which shows the beam receiving metal fitting and covering metal used for the beam attachment structure of the guard fence shown in FIG. FIG. 2 is a perspective view of a beam receiving bracket and beam fixing bolts and nuts used in the beam mounting structure of the guard fence shown in FIG. 1. FIG. 3 is an explanatory view showing a tightening operation of beam fixing bolts and nuts by a tightening tool in the beam mounting structure of the guard fence shown in FIG. 1. FIG. 2A is a front view showing a state where the protective fence beam mounting structure shown in FIG. 1 is installed on a flat ground, and FIG. FIG. 2A is a plan view showing a state where the protective fence beam mounting structure shown in FIG. 1 is installed on a straight portion of a road, and FIG.

Embodiments of the present invention will be specifically described below with reference to the drawings.
In the figure, reference numeral 1 denotes a plurality of pillars standing on the ground at intervals, 2 is a base metal fitting abutting against the side face of the pillar 1, S is a beam support metal, and the beam support metal S is The beam receiving metal fitting 3 is disposed outside the base metal fitting 2 and receives the end of the beam B, and the covering metal fitting 4 is placed on the beam receiving metal fitting 3 and covers the end of the beam B.

  As shown in FIG. 3, the base metal fitting 2 is provided with an outer surface 21 that is a first hemispherical mounting surface, and the base end of the beam receiving metal 3 has an outer surface 21 of the base metal fitting 2. A concave curved surface 31 which is a second mounting surface having a hemispherical shape corresponding to the shape is provided, and the outer surface 21 and the concave curved surface 31 are arranged to face each other and come into contact with each other. 11 is inserted into the first bolt hole 22 and the second bolt hole 32 provided in communication with the outer side surface 21 and the concave curved surface 31, and the bracket mounting bolt 5 and the bracket The mounting nut 6 is screwed and attached to the support column 1.

  The first bolt hole 22 provided on the outer surface 21 of the base metal fitting 2 is circular, and two lateral guide grooves 23 are formed on the left and right sides of the first bolt hole 22. A pair of retaining holes 24 are formed, and the second bolt holes 32 provided on the concave curved surface 31 of the beam bracket 3 are formed as cross-shaped holes including a vertically long hole portion 321 and a horizontally long hole portion 322. , Projections 33 are formed at both end edges 323 of the horizontally elongated hole 322.

  On the left and right sides of the guide groove 23 on the outer surface 21 of the base metal fitting 2, there are provided three tilt adjustment mark holes 25 in the vertical direction. The middle tilt adjusting mark hole 25 is provided on an extension line of the guide groove 21, and the tilt adjusting mark hole 25 located above and below the guide groove 21 is provided at a position corresponding to the stop hole 24. As described above, by providing the inclination adjusting mark hole 25, the beam receiving metal fitting 3 is attached to the base metal fitting 2, that is, the guide groove 23 and the stop hole 24 are not visible from the outside, which will be described later. With the projection mark holes 39, adjustment corresponding to the inclination of the beam B can be easily performed.

  Further, a horizontal adjustment mark hole 26 is provided at an interval beside the middle inclination adjustment mark hole 25. As described above, by providing the horizontal adjustment mark hole 26, a state in which the beam receiving metal fitting 3 is attached to the base metal fitting 2, that is, a state in which the guide groove 23 and the stop hole 24 are not visible from the outside will be described later. With the projection mark hole 39, adjustment corresponding to the curve point of the beam B can be easily performed.

  A beam receiving portion 35 protrudes from a mounting wall 34 having a concave curved surface 31 that is a mounting surface of the beam receiving bracket 3 toward the tip, and vertical walls 36 are formed in the longitudinal direction at both ends of the beam receiving portion 35. The vertical wall 36 is notched on the side of the mounting wall 34 to form a notch 37, and on the other hand, at a position corresponding to the notch 37 of the covering metal 4 that covers the beam receiving metal 3. A protruding wall 41 that fits into the notch 37 is formed. That is, when the covering metal fitting 4 is put on the beam receiving metal fitting 3, the protruding wall 41 and the cutout portion 37 are fitted so that the metal fittings are not displaced from each other.

  A beam fixing bolt 7 and a beam fixing bolt for fixing the beam receiving metal 3 and the covering metal 4 to the beam B through the vertical wall 36 of the beam receiving metal 3 and the side surface 42 of the covering metal 4. Through holes 38 and 43 for inserting cylindrical nuts 8 to be screwed into the holes 7 are formed, respectively, and the surface side of the through holes 43 located on the outer side is a flange shape formed in the beam fixing bolts 7 and the nuts 8. A stepped portion having a depth not projecting the heads 71 and 81 is formed into a circular countersink hole formed as a countersink portion 44, and the back side of the through hole 43 is connected to the beam fixing bolt 7. A hexagonal portion corresponding to a hexagonal neck lower portion 72 formed below the head portion 71 is formed as a hexagonal portion, that is, a hexagonal hole. The through hole 38 located on the inner side is formed in a hexagonal shape corresponding to the hexagonal neck lower part 72 formed below the head 71 of the beam fixing bolt 7, similarly to the back side of the through hole 43. It is a hexagonal portion, that is, a hexagonal hole. By doing in this way, since the beam fixing bolt 7 and the nut 8 do not protrude from the surface of the covering metal fitting 4, it is possible to prevent injury even if a human hand or the like hits it.

  In this embodiment, the through holes 38 and 43 formed in the vertical wall 36 of the beam receiving bracket 3 and the side surface portion 42 of the covering bracket 4 correspond to the hexagonal neck lower portion 72 of the beam fixing bolt 7. Since it has a hexagonal hole shape, the beam fixing bolt 7 can be inserted and screwed from either the left or right side of the beam support fitting, and the work efficiency for attaching the beam B can be improved.

  The beam receiver 3 is provided with a protrusion mark hole 39 on the side surface of the mounting wall 34 on the extension line of the protrusion 33, and the beam receiver 3 is attached to the base metal 2, that is, the base metal 2. Even when the guide groove 23, the stop hole 24, and the projection 33 of the beam receiving metal fitting 3 are not visible from the outside, the position of the projection 33 can be recognized, and the inclination adjustment mark hole 25 and the horizontal adjustment mark hole described above. The angle of the beam B can be easily adjusted with the projection 26 and the projection mark hole 39.

  In this embodiment, the cylindrical nut 8 has a cylindrical cylindrical portion 82 formed below the flange-shaped head portion 81, and a female screw is formed on the inner peripheral surface of the cylindrical portion 82. The outer shape of the cylindrical portion 82 is cylindrical, and the outer diameter of the cylindrical portion 82 is hexagonal through holes 38 and 43 formed in the vertical wall 36 of the beam receiving bracket 3 and the side surface portion 42 of the covering bracket 4. The diameter is smaller than the inscribed circle. A hexagonal hole 83 is formed in the center of the flange-shaped head 81, and a hexagonal wrench is inserted into the hexagonal hole 83 and tightened.

Next, a method for attaching the beam B to the column 1 will be described.
As shown in FIG. 2, the bracket mounting bolt 5 is inserted into the mounting hole 11 formed in the column 1, and the bracket mounting bolt 5 is inserted into the first bolt hole 22 of the base bracket 2 and the second of the beam receiving bracket 3. The metal fitting mounting nut 6 is screwed by using a tightening tool K such as a spanner. Next, the beam B is placed on the beam receiving portion 35 of the beam receiving bracket 3, and the covering bracket 4 is covered thereon, and the mounting hole A formed at the end of the beam B and the through hole 38 of the beam receiving bracket 3. The beam B is attached to the column 1 by aligning the hole positions of the through-holes 43 of the cover metal 4, penetrating the beam fixing bolts 7, and screwing the nuts 8.

  When the beam B is adjusted in the left-right direction with respect to the column 1, the protrusion 33 can be inserted into the guide groove 23 of the base metal fitting 2 and moved along the guide groove 23. Yes. Thus, the adjustment operation of the beam B can be performed efficiently and reliably. Further, when the beam B is inclined in the vertical direction with respect to the support column 1, the projection 33 can be inserted into the retaining hole 24 of the base metal fitting 2. Thus, it is preferable that the adjustment operation of the beam B can be efficiently and reliably performed as in the case of adjusting the beam B in the left-right direction.

  The protrusion 33, the guide groove 23, and the stop hole 24 may have any size as long as the protrusion 33 can be inserted into the guide groove 23 and the stop hole 24. However, the protrusion 33 is extremely protruded from the guide groove 23 and the stop hole 24. If 33 is small, when the protrusion 33 is inserted into the guide groove 23 and the retaining hole 24, the backlash between the base metal fitting 2 and the beam receiving metal 3 becomes large and it becomes difficult to adjust the direction of the beam B. Further, it is preferable that the size of the protrusion 33 is slightly reduced with respect to the stop hole 24. In this way, when adjusting the direction of the beam B, it is preferable that the beam B can be reliably held without being substantially displaced downward.

  When the bracket mounting nut 6 is rotated by the tightening tool K, the tightening tool K is not obstructed by the vertical wall 36 by the notch 37 formed in the beam receiving bracket 3. Therefore, the workability of the protective fence can be improved.

  Further, since the hexagonal neck lower portion 71 of the beam fixing bolt 7 is caught in the hexagonal through hole 43 of the covering metal fitting 4, a hexagon wrench or the like can be tightened without holding the beam fixing bolt 7 by hand. The nut 8 can be tightened with the working tool K, and the workability of the protective fence can be improved.

  In the above-described embodiment, the protrusion 33 is formed on the edge 323 of the horizontally long hole 322 of the beam bracket 3. However, the present invention is not limited to this, and the protrusion 33 is formed on the extension of the horizontally long hole 322. May be.

  Further, the guide groove 23 and the stop hole 24 are formed in the base metal fitting 2 and the projection 33 is formed in the beam receiving metal 3. Conversely, the projection is formed in the base metal fitting 2 and the beam receiving metal 2 is formed. Guide grooves and stop holes may be formed.

  The shape of the through hole 38 formed in the beam receiving bracket 3 is not particularly limited as long as the neck lower portion 71 of the beam fixing bolt 7 can be inserted, but the same shape and the same size as the through hole 43 formed in the covering metal fitting 4 are used. In this case, it is possible to ensure the hooking of the lower neck portion 71 and to reduce the thickness of the vertical wall 36 and the side surface portion 42.

  Further, the hexagonal neck lower portion 71 is formed on the beam fixing bolt 7, but the neck lower portion is formed below the head 81 of the nut 8, and the beam fixing bolt 7 is rotated and screwed into the nut. You may do it.

  Further, the shape of the lower part of the neck formed on the beam fixing bolt 7 or the nut 8 is not limited to the hexagonal shape, and may be a polygonal shape such as a quadrangular shape or an octagonal shape. In short, it is only necessary that when tightening the bolts and nuts, only the other can be tightened with the tightening tool K and the workability of the protective fence can be improved without holding one by hand.

  Further, the vertical wall 36 of the beam receiving bracket 3 may be positioned outside the side surface portion 42 of the covering metal fitting 4, and in that form, a countersunk portion is formed on the vertical wall 36 of the beam receiving bracket 3. Will be.

  In the present embodiment, the projection mark hole 39 is a concave hole, but is not limited to this, and may be a projection. In short, it may be a mark for adjusting the angle of the beam B.

  According to the beam mounting structure of the guard fence according to the present invention, the base bracket includes a base bracket disposed on the support column side, and a beam support bracket disposed outside the base bracket to support the beam. The support metal fitting has a hemispherical convex first mounting surface provided on either side opposed to a hemispherical concave second mounting surface provided on the other side, and on both the mounting surfaces. A bracket mounting bolt inserted into the first bolt hole and the second bolt hole provided in communication with each other is penetrated through the mounting hole of the column, is attached to the column, and is provided on the mounting surface. The bolt hole is formed with a lateral guide groove on at least one of the left and right sides thereof, and a stop hole is formed above and below the guide groove. Further, the second bolt hole has a vertically long hole portion and a horizontally long hole. And a cross-shaped hole made of a portion, A protrusion is formed on the edge of the long hole portion or an extension thereof. When adjusting the beam in the left-right direction with respect to the support column, the protrusion is inserted into the guide groove of the base metal fitting, and along the guide groove. When the beam is moved and tilted in the vertical direction with respect to the support column, the projection can be inserted into the retaining hole of the base metal fitting. Protective fences that can be installed efficiently and reliably using the same metal fittings, even when adjusting and installing protective fences, or when installing protective fences by adjusting the beam vertically such as on slopes It can be suitably used as a beam mounting structure for a fence.

DESCRIPTION OF SYMBOLS 1 Support | pillar 11 Mounting hole 2 Base metal fitting 21 Outer side surface 22 First bolt hole 23 Guide groove 24 Stopping hole 25 Marking hole for inclination adjustment 26 Marking hole for horizontal adjustment 3 Beam receiving metal fitting 31 Recessed curved surface 32 Second bolt hole 33 Protrusion 34 Mounting wall 35 Beam receiving portion 36 Vertical wall 37 Notch portion 38 Through hole 39 Protrusion mark hole 4 Cover metal fitting 41 Projecting wall 42 Side surface portion 43 Through hole 44 Countersink portion 5 Metal fitting bolt 6 Metal fitting nut 7 Beam fixing bolt 71 Neck lower part 72 Head 8 Nut 81 Head 82 Cylindrical part 83 Hexagonal hole S Beam support bracket B Beam

Claims (5)

  A base bracket disposed on the support column side and a beam support bracket disposed on the outer side of the base bracket to support the beam. The base bracket and the beam support bracket are provided on either one of the hemispherical protrusions. And a first bolt hole provided in communication with the two mounting surfaces and a second bolt surface are disposed opposite to the hemispherical concave second mounting surface provided on the other side. The first bolt hole provided in the mounting surface is attached to at least one of the left and right sides of the first bolt hole that is attached to the support pillar through the bracket mounting bolt inserted into the bolt hole. Direction guide grooves are formed, stopper holes are formed above and below the guide grooves, and the second bolt hole is a cross-shaped hole composed of a vertically long hole portion and a horizontally long hole portion, and the horizontally long A protrusion is formed on the edge of the hole or on its extension. When adjusting the beam in the horizontal direction with respect to the column, the protrusion is inserted into the guide groove of the base metal fitting, moved along the guide groove, and tilted in the vertical direction with respect to the column. Is a beam mounting structure for a protective fence, wherein the protrusion can be inserted into a retaining hole of a base metal fitting.   A hemispherical convex first mounting surface is provided on the base bracket, and a hemispherical concave second mounting surface is provided on the column-side surface of the mounting wall provided at the base end of the beam support bracket. 2. The beam mounting structure for a protective fence according to claim 1, wherein the beam-side surface of the wall is a hemispherical convex surface.   The beam support bracket includes a beam receiving bracket that receives a beam end portion and a covering bracket that covers the beam end portion and covers the beam end portion, and is an attachment surface that is disposed opposite to an attachment surface provided on the base bracket. The beam mounting structure for a protective fence according to claim 1 or 2, wherein the beam receiving bracket is provided.   A beam receiving portion protrudes outward from the mounting wall of the beam receiving bracket, and a vertical wall is erected in the longitudinal direction at both ends of the beam receiving portion, and the mounting wall side of the vertical wall is A cutout portion is formed by cutting out, and a protruding wall that fits into the cutout portion is formed at a position corresponding to the cutout portion of the covering metal fitting that covers the beam receiving metal fitting. The beam mounting structure for a protective fence according to claim 3.   A beam fixing bolt for passing through the vertical wall of the beam receiving bracket and the side surface of the covering bracket and fixing the beam receiving bracket, the covering bracket and the beam, and a cylindrical shape screwed to the beam fixing bolt. A through hole for inserting the nut is formed, and the through hole is formed with a counterboring portion having a depth that does not protrude the flange-shaped head formed on the beam fixing bolt and the nut, and the beam fixing bolt. 5. The beam mounting structure for a protective fence according to claim 3, wherein a polygonal portion corresponding to a polygonal lower neck portion formed below one of the heads of the nut and the nut is formed.

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