JP2006097707A - Reinforcing structure of synthetic resin bolt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure constituted by inserting a reinforcing core member into the inside of a synthetic resin bolt to reinforce the bolt and capable of reducing capacity of the reinforcing core member as much as possible and providing a bolt having strength equivalent to that of a conventional steel-made bolt. <P>SOLUTION: This reinforcing structure of the synthetic resin bolt has a spiral shaft part provided with a spiral part formed by injection-molding synthetic resin on an outer peripheral face. The reinforcing core member constituted by a hard steel wire and extending in the axial direction is buried inside the spiral shaft part. At least two bent parts formed by bending a part in the vicinity of an end part of the hard steel wire forming the reinforcing core member are provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a reinforcing structure of a synthetic resin synthetic resin bolt suitable as a dog nail bolt used for fixing a railroad rail to a sleeper.

  As shown in FIG. 4, a conventional dog peg bolt is made of a hexagonal bolt made of steel, and a tool engaging portion consisting of a hexagonal head is provided at one end of a screw having a large pitch helix. Galvanized and rustproof.

  By the way, in the method of fixing the rail to the sleeper with this dog nail bolt, when the electric power supplied to the electric motor of the train returns to the power supply facility through the rail, a part of the electric power leaks to the ground surface through the dog nail bolt, and the bottom of the rail is There was a failure to corrode electrically.

As a measure to improve this, replace all or part of the steel nail bolt with synthetic resin.
In addition, attempts have been made to prevent energization by applying a synthetic resin coating on the surface.

  However, since synthetic resin is generally inferior in strength to steel, replacing steel that forms dog-nail bolts with synthetic resin requires bolts with an excessive diameter to obtain the required mechanical strength, and the gap between conventional bolts Incompatible. For this reason, in order to employ the synthetic resin bolt, there is a problem that it is unavoidable to replace the sleepers together and the cost for replacement becomes excessive.

It was also attempted to make the outer diameter of the dog nail bolt slightly narrower and to cover the outer surface with a synthetic resin for insulation.
In order not to reduce the mechanical strength, it is necessary to add a process such as high-quality steel or heat treatment, and when the nail bolt is heated to high temperature by solar heat due to the difference in thermal expansion coefficient, the synthetic resin film cracks. As a result, the electrical insulation properties may be impaired. Moreover, since the effect of weight reduction is small and heavy, handling at the work site is inconvenient. JP 11-201125 A Japan Railway Facility Association magazine vol. 2000-5, page 280 "Resin rail fastening bolt"

  In order to solve the above-mentioned problems, the inventor obtained an idea of manufacturing a synthetic resin bolt having a high tensile strength by inserting a piano or other highly drawn steel wire known to have a high tensile strength. However, since these steel wires have a smooth surface and a small contact area with the synthetic resin, sufficient adhesion cannot be obtained with the synthetic resin as the base material, and the required tensile strength may not be obtained. there were.

  Further, when trying to rotate the synthetic resin dog bolt with a tool such as a spanner, the hexagon head is damaged, and it is difficult to transmit the rotational force applied by the tool to the reinforcing core. That is, when the spanner is rotated, it is difficult to obtain the required tensile strength because it is sheared in a cylindrical shape between the bent portion and the outer surface of the screw or the screw is broken.

  The present invention has a screw shaft portion provided on the outer surface with a spiral formed by injection molding of synthetic resin, and a reinforcing core material that is made of a hard steel wire and extends in the axial direction is embedded in the screw shaft portion. At the same time, the main feature is that at least two bent portions are provided by bending the vicinity of the end of the hard steel wire forming the reinforcing core.

  In the synthetic resin bolt according to the present invention, the synthetic resin as a base material is reinforced by a reinforcing core material having a relatively small cross-sectional area and high strength. A synthetic resin bolt free from defects that easily cause cracks on the surface is obtained.

  Reinforcement core material is made of drawn steel wire, and is composed of straight and bent parts, and the area of the part receiving the external force received by the synthetic resin part such as the bent part and the spiral part becomes larger and the surface pressure becomes smaller. Without damaging the resin portion with inferior mechanical strength, the force supported by the bent portion is reliably transmitted to the straight portion of the reinforcing core. Therefore, it can withstand a larger tensile force than when there is no bent portion.

  In addition, the reinforcing core material is made of hard wire such as hard steel wire or piano wire, and can be manufactured by a simple process of winding a part of it into a ring shape. There is an advantage that the cost of the core material can be kept low.

  The purpose of obtaining a synthetic resin bolt having both mechanical strength comparable to that of a bolt made of mild steel and electrical insulation by inserting a strong reinforcing core material into the synthetic resin, By using a drawn steel wire as the reinforcing core material, the manufacturing process is realized without being excessively complicated.

  FIG. 1 shows an embodiment of a synthetic resin bolt according to the present invention, specifically a dog peg bolt for fixing a railroad rail to a sleeper. The dog bolt 10 as a synthetic resin bolt is configured as a so-called hexagon bolt having a screw shaft portion 12 having a spiral on the outer surface and a hexagonal tool engaging portion 14, and is an engineering plastic reinforced with glass fiber. It is made by injection molding. Reference numeral 16 denotes a shaft rod 16 that is slightly thicker than the screw shaft portion 12, and the screw shaft portion 12 and the tool engagement portion 14 are coaxially connected via the shaft rod 16.

  Inside the synthetic resin forming the synthetic resin bolt 10, six highly-stretched drawn steel wires 20 extending in the axial direction are inserted as reinforcing cores. In this embodiment, the drawn steel wire 20 is a piano wire (JIS SWP) or a hard steel wire (JIS SWC) having a tensile strength of about 180 kg / mm @ 2. Thus, the synthetic resin bolt 10 is obtained by adding the high strength of the drawn steel wire 20 to the strength of the synthetic resin as a base material, thereby obtaining a high tensile strength as a whole.

  The six drawn steel wires 20 as reinforcing core members are arranged around the axis line in correspondence with the six top portions of the hexagonal heads forming the tool engaging portion 14, and they are arranged around the synthetic resin bolt 10. The screw shaft portion 12 and the tool engagement portion 14 are connected to each other and extend substantially over the entire length.

  As shown in FIG. 2, the drawn steel wire 20 has a linear shape cut into a straight line having a predetermined length so that the end portions 21 and 21 are held in a forming die. It has become. The drawn steel wire 20 is provided with a first bent portion 22 in the vicinity of one end corresponding to the position of the tool engaging portion 14 and a second bent portion 23 at a position corresponding to the screw shaft portion 12.

  As shown in FIG. 3, both the bent portions 22 and 23 are formed by winding a part of the drawn steel wire 20 in a ring shape. It is folded in the shape of a ring that is folded back in the pulling direction. The ring-shaped configuration will be described more specifically. The ring includes a circular arc portion C formed of a small arc bent with a radius slightly smaller than the wire diameter of the drawn steel wire 20, and a linear portion L continuous in a tangential direction from both ends thereof. And a plurality of combinations H are provided.

  Thus, when tension is applied to the synthetic resin bolt 10, the drawn steel wire 20 is retained by the first bent portion 22 and the second bent portion 23, so that the screw shaft portion 12, the tool engaging portion 14, The tension acting during this time is effectively transmitted to the drawn steel wire 20 and can withstand a large force. Further, at this time, it is possible to prevent the drawn steel wire 20 from sliding on the inside of the synthetic resin as a base material in the axial direction and bearing the load.

  As is apparent from FIG. 1A, six drawn steel wires 20 are provided at substantially the same position in the longitudinal direction of the first bent portion 22, and each first bent portion 22 is formed from the position of the drawn steel wire 20. It is wound toward the top of the corresponding hexagon head and extends radially outward. Therefore, even if the first bent portion 22 is made relatively large in the radial direction at the position of the tool engaging portion 14, it does not protrude from the hexagonal head. When the synthetic resin bolt 10 is tightened, the rotational force applied to the hexagonal head acts on the first bent portion 22 and is transmitted to the second bent portion 23 inserted in the screw shaft portion 12, Damage to the synthetic resin forming the screw shaft portion 12 is avoided. Furthermore, since a part of the outer surface of the first bent portion 22 faces the fastening surface 10a of the synthetic resin bolt 10, the distance between the outer surface of the first bent portion 22 and a member to be fastened such as a nut is small, Strong fastening force can be obtained.

  The second bent portion 23 provided on each of the six drawn steel wires 20 is wound in the opposite direction to the first bent portion 22 and in substantially the same shape, and is shifted in the axial direction. These are housed in the screw shaft portion 12 so as not to interfere with each other. Thus, the reinforcing strength in the axial direction of the screw shaft portion 12 by the drawn steel wire 20 increases from the end portion toward the tool engagement portion 14, and the shaft rod on which the greatest tension acts on the screw shaft portion 12. As shown in FIG. 1 (C), six steel wires 20 are arranged around the axis to adjoin a large tensile force at a portion adjacent to 15.

  Therefore, when a tensile force acts on the dog nail bolt 10, first, the synthetic resin as a base material extends, and the tensile force also acts on the drawn steel wire 20 due to the elongation. At this time, since the drawn steel wire 20 has less elongation than the synthetic resin, the drawn steel wire 20 tends to slip between the base resin and the joint resin, but the bent portions 22 and 23 are formed into a ring shape by combining the arc and the straight line. The pulling of the nail bolt 10 can be greatly improved even if the base material is a synthetic resin.

  Forming the first bent portion 22 and the bent portion 23 in the shape of a ring as described above is not an essential requirement in terms of the configuration of the invention, and as shown in FIG. It may be configured to be bent into a letter shape. Hereinafter, modified examples will be described. In the figure, the same parts as those in the first embodiment are designated by the same reference numerals and the description thereof is omitted.

  In the drawing (a), the drawn steel wires 20 are arranged over substantially the entire length of the synthetic resin bolt 10, and six wires are arranged equally around the axis. Here, the first bent portion 22 is formed by bending the drawn steel wire 20 outward in the radial direction of the synthetic resin bolt 10 and then bending it in parallel, then bending it back to the original position and bending it into a substantially U shape. The 1st bending part 22 which belongs to the two drawn steel wires 20 in a position is arrange | positioned on the same plane. As a result, four sets of combinations H of the arc portion C and the straight portion L are formed. Further, the second bent portion 23 is also bent in a substantially U shape in the opposite direction to the first bent portion 22, but the parallel bent portion interferes with the drawn steel wire 20 in the symmetric position, so that it interferes with each other. To avoid this, an angle is provided as shown in FIG.

As described above, the synthetic resin bolt 10 uses the drawn steel wire 20 having a large tensile strength as the reinforcing core material. Therefore, a sufficient tensile strength can be obtained with a small amount of steel, and the weight can be reduced.
In addition, although the drawn steel wire 20 having a small surface area is used as the reinforcing core, the first bent portion wound in a circle in the straight portion is used. Since the bent portion 22 and the second bent portion 23 are provided, the drawn steel wire 20 is not pulled out, and the contact area between the synthetic resin as the base material and the drawn steel wire 20 is increased. Sufficient reinforcement can be obtained because of the close contact.

  Further, as a means for increasing the contact area between the synthetic resin and the drawn steel wire 20, the structure of the bent portion wound in a ring shape is adopted, so that the drawn steel wire 20 can be easily formed and can be manufactured at low cost. is there.

  Although the said Example showed the example of the hexagon bolt, it is applicable not only to this but various bolts, such as a stud bolt and a hexagon socket head bolt.

It shows the relationship between a synthetic resin bolt and a drawn steel wire, which is an embodiment of the present invention, (a) is a plan view, (b) is a front view, and (c) is C in (b) above. It is -C sectional drawing. The drawing shows a drawn steel wire as a reinforcing core, wherein (a) is a front view of the drawn steel wire 20, (b) is a plan view of (a), and (c) is a CC cross section in (a). FIG. 4D is a sectional view taken along the line DD. (Example 1) It is an external view of the hexagon bolt which is an example of a synthetic resin bolt, (a) is a top view, (b) is a front view. The other Example of the drawn steel wire which is a reinforcement core material is shown, (a) is a front view, (b) is a bottom view. (Example 2) The external appearance of the conventional iron dog nail bolt is shown, (a) is a top view, (b) is a front view.

Explanation of symbols

10 Dog nail bolt (synthetic resin bolt)
10a Fastening surface 12 Screw shaft portion 14 Tool engaging portion 16 Shaft 20 Pulled steel wire (reinforcing core material)
22 1st bending part 23 2nd bending part C Circular arc part L Straight line part H Combination

Claims (6)

  It has a screw shaft portion provided on the outer peripheral surface with a spiral formed by injection molding synthetic resin, and a reinforcing core material that is made of a hard steel wire and extends in the axial direction is embedded in the screw shaft portion, and A synthetic resin bolt reinforcing structure in which at least two bent portions are provided by bending the vicinity of an end of a hard steel wire forming a reinforcing core.   A tool engaging portion enlarging outward is provided at one end of a screw shaft portion provided with a spiral on the outer peripheral surface, and one side from the axis of the screw shaft portion between the screw shaft portion and the tool engagement portion. A first bending portion in which a reinforcing core member made of a hard wire extending in the axial direction is arranged at a position biased to the outer periphery and bulges outward in the circumferential direction in accordance with the position of the tool engaging portion on the reinforcing core member. A synthetic resin bolt reinforcing structure in which the first bent portion and the second bent portion bulged in the axial direction are formed corresponding to the positions of the portion and the screw shaft portion.   3. A plurality of hard steel wires forming the reinforcing core member are arranged around the axis of the screw shaft portion, and the first bent portion provided on the hard steel wire forming the reinforcing core member is disposed radially outward. Reinforced structure of synthetic resin bolts that are bulged out.   3. The tool engaging portion according to claim 2, wherein the tool engaging portion is a hexagon head, and six hard steel wires forming the reinforcing core are arranged around the axis of the screw shaft portion so as to correspond to the top portions of the hexagon head, A reinforcing structure of a synthetic resin bolt in which one bent portion is bulged in the direction of each top of the hexagon head.   In Claim 1, the hard steel wire which makes the said reinforcement core material is bent, and at least 1 each ring-shaped bending part is provided in the one end located in the said tool engaging part side, and the other end located in the screw shaft part side. Reinforced structure of synthetic resin bolts.   6. The synthetic resin bolt reinforcement structure according to claim 5, wherein the annular bent portion is formed by an arc portion formed by bending a hard steel wire forming a reinforcing core, and a linear portion connected to both ends of the arc portion. .

Images