JP2014080831A - Track pad with hole for spring constant adjustment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a track pad with a hole for spring constant adjustment, which is substituted for a track pad with a groove for spring constant adjustment.SOLUTION: A track pad (10) with a hole for spring constant adjustment includes a rubber-made plate-like member (20) having a top surface (12), an undersurface (14) and a peripheral surface (16). The rubber-made plate-like member includes a hole (22) for spring constant adjustment, which is elongated almost in parallel with the top surface and the undersurface, between the top surface and the undersurface.

Description

  The present invention relates to a track pad set between a railway sleeper and a rail, between a tie plate fixed on the sleeper and a rail, or under a tie plate or a sleeper.

  The track pad is a flat pad that is mostly made of rubber and is mainly used for cushioning. With the speeding up of railways, it is important to take measures against vibration of the rail track and the noise associated therewith, and the track pad used as a shock absorber for vibration on the rail track is required to improve its buffering performance. (See Patent Document 1)

  The track pad is a flat plate made of natural rubber or synthetic rubber, and in order to improve the buffering performance, it was standardized to make a groove or other recess on the upper or lower surface or any one of the surfaces. It is a specification, and the required buffer performance is obtained by adjusting the spring constant by adjusting the size and number of the recesses.

  On the other hand, this track pad is required to withstand long-term use as much as possible. The Railway Research Institute (Railway Research Institute), one of the most important research institutes in Japan regarding railway technology, is also conducting research from this perspective. RRR (Railway Research) In the April 2011 issue of (Review), the following research report is generally made in a paper entitled “Maintenance Technology” (Non-Patent Publication 1).

  Regarding the deterioration of the track pad, “it is considered that there is no deterioration that causes a problem in the track leading to breakage or separation of the pad (8th to 9th lines from the bottom left column of RRR page 16)”, The decrease in the shock absorbing performance of the railroad is a disadvantageous change in the maintenance and maintenance of the railway environment, such as increasing the vibration of the track and accelerating the settlement of the track in the ballast track. It has been found that it is desirable to develop a track pad with small deterioration in buffer performance even if it is used (from the bottom of the right column on page 16 to the second column to the left column on page 17), This suggests that it is necessary to prevent a decrease in buffer performance, that is, a secular increase (deterioration) of the spring constant.

Furthermore, in this paper, under the title “Policy for the development of long-life products”, “(1) Use materials that do not easily deteriorate even when used at high temperatures. (2) Use materials that do not easily deteriorate even after repeated use. "The material for (1) has already been developed, but the current (1) is (1)." )), And there is no prospect of significant improvement. (3rd to 5th lines from the bottom of the left column on page 17) " It is possible to reduce the force itself (1 to 2 lines from the bottom of the same column). ”(If a groove is provided, stress concentration will occur at the corners and cause deterioration.) Considering (right column on the same page, lines 6-9)) --- (Omitted) --- It is thought that it is more advantageous for the durability of the track pad to reduce the spring constant with foamed rubber using flat rubber (right column, lines 3-6). And then
“Considering these, as a more specific policy for extending the service life of the track pad, (2) 'foam rubber is used instead of (2) to lower the spring by a flat plate shape.
Can be mentioned. (Same column, lines 10-13)
According to this policy, it is reported that development of a long-life track pad is being promoted (same column, lines 13 to 16).

April 2011 issue of Railway Research Institute "RRR" pages 14-17

  The applicant of the present application is a patent application (Japanese Patent Application No. 2011-138029) whose title is “Method for producing foamed rubber track pad” dated June 22, 2011 together with the National Railway Construction and Transportation Facility Maintenance Support Organization. ) This is in line with the technical flow described in the railway research report as described above. The inventor of the present application aims to provide a new orbit pad in another form in place of such a conventional orbit pad provided with a spring constant adjusting groove on the upper and lower surfaces.

That is, the present invention
A track pad comprising a rubber plate-like member having an upper surface, a lower surface and a peripheral surface,
The rubber plate-like member provides a track pad with a spring constant adjusting hole provided with a spring constant adjusting hole extending substantially parallel to the upper surface and the lower surface between the upper surface and the lower surface.

  Specifically, a plurality of the spring constant adjusting holes may be provided at intervals.

  More specifically, the spring constant adjusting hole may have a circular or oval cross section. In this case, the spring constant adjusting hole may have an oval cross section having a horizontal length longer than a vertical direction passing through the upper and lower surfaces.

  The spring constant adjusting hole may be provided so as to penetrate the rubber plate member. However, it is not always necessary to use a through hole.

  Further, at least one of the spring constant adjusting holes can be tapered in the length direction. When receiving a plurality of tapered spring constant adjusting holes, the at least one spring constant adjusting hole tapered in the length direction and the at least one spring constant adjusting hole taper in the opposite direction. The spring constant adjusting holes including at least one spring constant adjusting hole may be provided to be spaced from each other.

  Moreover, it is desirable that the upper surface and the lower surface of the rubber plate-like member in the track pad are planes parallel to each other.

  In the track pad according to the present invention, the track pad is provided by providing spring constant adjusting holes extending substantially parallel to the upper and lower surfaces in place of the spring constant adjusting grooves provided on the upper and lower surfaces of the track pad. The spring constant of can be adjusted. In the above-mentioned research report of the Railway Research Institute, the causes of reduced buffering characteristics of grooved track pads are (1) high heat environment under rail track exposed to hot weather, and (2) stress concentration due to formation of grooves. ing. In the present invention, the spring constant is adjusted by providing a spring constant adjusting hole extending in parallel with the upper and lower surfaces between the upper and lower surfaces of the pad instead of providing grooves on the upper and lower surfaces of the rubber plate-like member. Unlike the conventional spring constant adjusting groove provided on the surface of the rubber plate-like member, the spring constant adjusting hole is not directly exposed to a rail that becomes extremely hot in summer. In addition, air can enter and exit through the spring constant adjustment hole in the track pad, so that the environment of high heat is alleviated, and the buffer performance is degraded by the heat of the rubber plate member (track pad). Reduction can be expected. This is particularly true when the “height adjustment pad” is provided under the track pad. In other words, when laying the track pad, a “height adjustment pad” that adjusts the height of the rail by injecting resin into the bag inserted between the tie plate and the track pad may be used. If a conventional track pad with a spring constant adjustment groove is used as a pad, the "height adjustment pad" when the resin is in a semi-solid state before curing, that is, the bag follows the grooved bottom surface of the track pad. This is because it deforms and closes the groove.

  Further, in the conventional track pad with spring constant adjustment groove, the area of the upper surface contacting the bottom surface of the rail becomes smaller due to the spring constant adjustment groove, so the pressure receiving area becomes smaller and stress concentration tends to occur. In the track pad according to the present invention, the rail is received with the front surface of the upper surface as a flat surface, so that the pressure receiving surface is large and stress concentration is difficult to occur. As will be described later, an actual fatigue test was performed, that is, a fatigue test of a conventional track pad with a groove for adjusting a spring constant and a track pad with a spring constant adjusting hole according to the present invention having a spring constant equivalent thereto. As a result, it was verified that the track pad with spring constant adjusting holes according to the present invention showed superior numerical values compared with the conventional one. In this test, the track pad with the spring constant adjustment hole, which is an actual product, and the track pad according to the present invention produced for a track pad of another specification were tested, so the test conditions were completely consistent. Even if it cannot be said that the difference in the test results is significant, it is verified that at least the pad with the spring constant adjusting hole according to the present invention satisfies the predetermined standard. It was done.

  As described above, when a conventional track pad with a spring constant adjusting groove is used as the track pad, the height adjusting pad closes and hardens the track pad groove so that the spring constant of the track pad is set. There was a defect that was higher than the value. In the track pad according to the present invention, since the upper and lower surfaces can be flat, it is possible to avoid such a problem.

  In addition, when using the height adjustment pad, only the track pad with a deteriorated cushioning performance may be replaced and the height adjustment pad may be left as it is, but in this case, the height adjustment pad may be used. Since the protrusion corresponding to the spring constant adjusting groove of the track pad is left in the spring pad, the spring constant adjusting groove of the newly laid track pad does not match the protrusion, and proper laying may not be performed. Since the lower surface of the track pad according to the present invention can be flattened, even when the pad for adjusting the height is reused as described above, the track pad with the spring constant adjusting hole is removed and left behind. The height adjustment pad does not have the above-described protrusion, and therefore, a new track pad with a spring constant adjustment hole can be appropriately and easily laid. This makes it possible to greatly reduce the work time for exchanging the track pad with spring constant adjusting holes.

  There are the following advantages in making the cross section of the spring constant adjusting hole an oval instead of a circle. That is, when forming a hole in the track pad, it is necessary to leave a certain thickness above and below the hole in order to maintain the strength of the track pad, but when forming a hole with the same cross-sectional area, When the elliptical cross section is used, the thickness of the track pad left above and below the thickness is larger than when the circular cross section is used. In other words, if the hole is made to have a circular cross section and the thickness of the track pad portions left and above the hole is made to be the same as that of the hole having the oval cross section, the cross sectional area of the circular cross section is In order to obtain an equivalent spring constant, it is necessary to increase the number of springs, which makes it difficult to form. That is, as described below, as one embodiment of the present invention, a track pad with a spring constant adjusting hole is formed through a hole forming rod in a track pad forming mold, and the hole cross section is an oval. By doing so, the cross section of the hole-forming rod can be increased, so that bending and biasing of the rod during molding can be reduced, and it is easy to pull out the rod from the molded track pad Thus, the track pad can be easily formed.

  When the hole for adjusting the spring constant is tapered in the length direction, it is possible to more easily pull out the rod for forming the hole for adjusting the spring constant from the molded rubber taken out from the mold. To do.

  Embodiments of a track pad with a spring constant adjusting hole according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a perspective view of a track pad with a spring constant adjusting hole according to the present invention. It is a top view of the metal mold | die for shape | molding the track pad of FIG. FIG. 3 is an end view of the mold of FIG. 2. It is a top view of the rubber material after shaping | molding taken out from the metal mold | die. It is a schematic perspective view of an apparatus for pulling out a rod for forming a spring constant adjustment hole from a molded rubber material extracted from a mold. It is a top view which shows the modification of the track pad with the spring constant adjustment hole of FIG. It is a figure which shows the cross-sectional shape and size of the hole for spring constant adjustment provided in the track pad based on this invention created in order to perform a fatigue test.

  A track pad 10 with a spring constant adjusting hole according to the present invention shown in FIG. 1 includes an upper surface 12 and a lower surface 14 which are parallel to each other, and a peripheral surface 16 extending between the peripheral edges of the upper surface 12 and the lower surface 14. A rubber plate-like member 20 is provided. Although it is possible to provide a general-purpose iron plate or a super hard rubber surface member on the upper surface 12 of the rubber plate-like member 20, in the illustrated example, there is no such surface member.

  As shown in the figure, the rubber plate member 20 extends between the upper surface 12 and the lower surface 14 substantially parallel to the upper surface 12 and the lower surface 14, and has a spring constant adjusting hole 22 penetrating the rubber plate member 20. Prepare. In the illustrated example, a plurality of spring constant adjusting holes 22 are provided at intervals. The spring constant adjusting holes 22 are parallel to each other, but are not necessarily parallel to each other, and the number, size, etc., of the spring constants required for the rubber plate-like member as a whole are taken into consideration. It is determined as appropriate.

  The spring constant adjusting hole 22 has a circular or oval cross section, but the example shown in the drawing shows an oval cross section. Here, “oval shape” means a shape that is longer in the horizontal direction than the vertical direction passing through the top and bottom surfaces and has both ends arced, and the left and right ends are rounded in an elliptical shape or a flat rectangular shape. It is meant to include the shape of the shape.

  The reason why the cross section is circular or oval is to prevent a corner portion where stress concentration occurs on the inner peripheral surface of the spring constant adjusting hole 22 from occurring. In addition, it is preferable to have an oval shape rather than a circular cross section, and this is the length (thickness) from the hole to the upper surface 12 and the lower surface 14 in the case of an oval shape even in a hole having the same cross-sectional area. This is because the required strength as the orbit pad is maintained.

  2 and 3 are conceptual diagrams of a mold when the rubber plate-like member 20 is molded. That is, the mold 30 is set between a mold body 38 including a mold upper part 34 and a mold lower part 36 which are struck together to form a mold space 32, and the mold upper part 34 and the mold lower part 36. And a plurality of rods 40 set so as to traverse the mold space 32. The rod 40 has the same elliptical cross section as the cross section of the spring constant adjusting hole 22 to be formed, and is connected by an elongated connecting member 42 at one end. The rod can be handled integrally.

  In the case of molding the rubber plate-like member 20 described above, a rubber material is loaded into the lower mold part 36, a rod 40 is set so as to cross over the rubber material, and an additional rubber material is placed thereon. In this state, the mold upper part 34 is overlapped with the mold lower part 36, and the rubber material inside is pressure-heated to perform vulcanization molding of the rubber material. After molding, the molded rubber material is taken out together with the rod 40 and its connecting member 42, and the rod 40 is pulled out from the molded rubber material 44 (FIG. 4). The molded rubber material from which the rod has been removed is subjected to necessary cutting at the peripheral portion in accordance with the size of the track pad as the final product.

  FIG. 5 shows a schematic diagram of an apparatus for pulling out the rod from the molded rubber material 44. As shown in the figure, this apparatus has an air piston cylinder 50 fixed on a base (not shown), and is engaged with the connecting member 42 at the tip of a piston rod 54 extending from the cylinder 52. A mating elongated engagement member 56 is provided. Further, the base is provided with a locking member 58 for locking the molded rubber material 44 by engaging with the end face of the rod 40 of the molded rubber material 44 extracted from the mold. Yes. In order to pull out the rod 40 from the molded rubber material 44 using this device, the rod extending from the molded rubber material 44 extended from the cylinder 52 and locked by the locking member 58 on the base is used. The engaging member 56 at the tip of the piston rod 54 is engaged with the 40 connecting members 42. In this state, the air piston cylinder 50 is driven so as to pull the piston rod 54 into the cylinder 52, whereby the rod 40 is pulled out from the molding rubber material 44. The molded rubber material 44 from which the rod 40 has been pulled out is appropriately cut at its periphery to form a required track pad.

Fatigue tests were conducted on the “sag” and “spring constant” of the raceway pad with spring constant adjustment holes formed as described above and the conventional raceway pad with grooves for spring constant adjustment.
A. Fatigue test 1 (slip test)
(A) Specimen (The prepared specimens are the following two types)
1. Hole type (10.5 × 50 × 50mm)
As shown in FIG. 7, a plurality of through-holes having a long hole-shaped cross section having a semicircular portion of both ends with a radius of 2.5 mm and a straight portion of 4 mm in length connecting the semicircular portions are provided according to the above-mentioned present invention. Cut out from the track pad (10.5 × 140 × 178mm: spring constant 30MN / m) specified as the “buffer pad”.
2. Grooved type (12 × 50 × 50mm)
Cut from a conventional track pad (12 x 140 x 180 mm: spring constant 28 MN / m) with grooves on the top and bottom according to the railway construction and transport facility maintenance support organization standard "low spring track pad".

(B) Load conditions:
Frequency: 5Hz
Repeat load: 9kN ± 6kN (sine)
Number of times: 1 million times

(C) Test results by fatigue test type

B. Fatigue test 2 (spring constant test):
(a) Test piece:
Same as fatigue test 1 above.

(B) Load conditions
Frequency: 5Hz
Repeat load: 9kN ± 6kN (sine)
Number of times: 3 million times

(C) Comparison of spring constant before and after fatigue test

C. Evaluation of Test Result The track pad, which is the test target of this test, is a track pad for the purpose of buffering. In the sag test of this type of track pad, the sag amount under the above test conditions is qualified within 10%. Therefore, it can be seen that the track pad with spring constant adjusting hole according to the present invention is sufficiently qualified in this respect. Further, even when compared with a conventional grooved type, excellent values are shown in the rate of change of “sag” and “spring constant”.

  As shown in FIG. 6, the spring constant adjusting hole 22 can be tapered (tapered) along its length. By attaching such a taper, the rod 40 can be easily pulled out and the track pad can be easily manufactured. In the illustrated orbit pad 10, the taper direction is alternately reversed for each adjacent spring constant adjusting hole 22. In this case, the above-described rod 40 for molding the spring constant adjusting hole 22 is tapered corresponding to the spring constant adjusting hole 22 to be molded, and when the rod is pulled out from the molding rubber drawn out from the mold, Every other rod having a taper in the same direction is pulled out in the direction in which the diameter of the rod increases.

  The embodiments of the track pad according to the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications can be made. For example, the spring constant adjusting hole may not penetrate the track pad.

Track pad 10; Upper surface 12; Lower surface 14; Peripheral surface 16; Rubber plate member 20; Spring constant adjusting hole 22; Mold 30; Mold space 32; Mold upper portion 34; 38; rod 40; connecting member 42; molded rubber material 44; air piston cylinder 50; cylinder 52; piston rod 54; engaging member 56;

Claims (8)

A track pad comprising a rubber plate-like member having an upper surface, a lower surface and a peripheral surface,
The rubber plate-like member is a track pad with a spring constant adjusting hole provided with a spring constant adjusting hole extending substantially parallel to the upper surface and the lower surface between the upper surface and the lower surface.   The track pad with spring constant adjusting holes according to claim 1, wherein a plurality of the spring constant adjusting holes are provided at intervals.   The track pad with a spring constant adjusting hole according to claim 1, wherein the spring constant adjusting hole has a circular or oval cross section.   The track pad with a spring constant adjusting hole according to claim 3, wherein the spring constant adjusting hole has an elliptical cross section having a horizontal length longer than a vertical direction passing through the upper and lower surfaces.   The track pad with a spring constant adjusting hole according to any one of claims 1 to 4, wherein the spring constant adjusting hole is provided so as to penetrate the rubber plate member.   The track pad with a spring constant adjusting hole according to any one of claims 1 to 4, wherein at least one of the spring constant adjusting holes is tapered in a length direction thereof.   The spring constant adjustment including at least one spring constant adjusting hole tapered in the length direction and at least one spring constant adjusting hole tapered in a direction opposite to the spring constant adjusting hole. The track pad with a spring constant adjusting hole according to any one of claims 1 to 4, wherein a plurality of holes are provided at intervals.   The track pad with a spring constant adjusting hole according to any one of claims 1 to 7, wherein the upper surface and the lower surface are planes parallel to each other.

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