JP6368566B2 - Track pad - Google Patents

Description

  The present invention relates to a track pad interposed between a tie plate fixed on a sleeper and a rail and having a required spring constant.

  Conventional rubber pads used natural rubber or SBR rubber (styrene butadiene rubber), but the rubber pads are turned off and removed by long-term use due to the expansion and contraction of the rails due to the cold and warm conditions. Have been frequent.

  As a track pad that has improved such a drawback, a steel pad bonded to the upper surface of a rubber material has been proposed. Since the steel sheet and the rubber material are inferior in adhesiveness, the steel sheet is easily peeled off from the rubber material, and a number of contrivances have been made so as not to be detached even if it is peeled off (for example, Patent Documents 1 to 3).

  However, even after many years of use, poor adhesion occurs, and the steel plate separates from the rubber pad due to the breaking force caused by the expansion and contraction of the rail and the vibration caused by the passing of the vehicle. There is a case where a serious failure such as a traffic signal failure occurs, for example.

  And as a track pad which improved these faults, what fixed ebonite instead of adhering a steel plate on the upper surface of a rubber material is proposed (for example, patent documents 4). Since the rubber member and ebonite are vulcanized and bonded together at the time of rubber vulcanization, the bonding surface is reactively bonded and the bonding reliability is high. This proposed product is excellent in that ebonite is good and the sliding adhesion is quite firm. However, in order to adjust the low spring constant, a method is adopted in which the thickness of the rubber material is thinned, that is, a concave portion is provided and the pressing area is adjusted. When repeatedly subjected to a high load for a long time, the rubber part having a small area is crisp and the rubber material has fallen off from the tie plate.

  On the other hand, in a track pad of a laminated product combining rubber material and steel material, an H-shaped one is proposed in which tongue-like portions (ear portions) projecting to both sides in the rail width direction are formed at both ends in the rail longitudinal direction of the steel material. (For example, Patent Document 5). In this track pad, the above-mentioned ear portion is engaged with the end surface of the tie plate in the rail longitudinal direction so as to regulate the positional deviation with respect to the tie plate.

Japanese Patent Laid-Open No. 07-238502 JP-A-10-237802 JP 2004-44113 A JP 2006-265841 A JP-A-11-323801

  However, even the track pad described in Patent Document 5 sometimes falls off the tie plate due to destruction or deformation of the ear portion of the steel material. Moreover, in such a case, the ear cannot be reused due to destruction or deformation of the ear. Even when the rubber track pad having the above ebonite surface material is formed in an H shape, the same problem as the track pad described in Patent Document 5 occurs.

  In view of the above-described facts, an object of the present invention is to provide a track pad that is difficult to drop off from a tie plate and contributes to being reusable even if it drops off.

  The above problem is solved by the following means.

The track pad according to the first aspect of the present invention is such that the pad main body, which is formed of a rubber foam and is interposed between the rail and the tie plate, projects downward from both ends in the rail longitudinal direction. Each protrusion is engaged with an end face of the tie plate in the longitudinal direction of the rail, and chamfered on the opposite side to the rail and opposite the tie plate at the both ends of the pad body. The part is formed .

The track pad according to a second aspect of the present invention is the track pad according to the first aspect, wherein the rubber-like foam has a density of 0.50 to 0.90 g / cm ³ and an elongation of 130% or more.

  A track pad according to a third aspect of the present invention is the track pad according to the first or second aspect, wherein the track pad is laminated on a surface of the pad body on the rail side and has a resin layer having a static friction coefficient of 0.35 or less. .

  According to a fourth aspect of the present invention, in the track pad according to any one of the first to third aspects, the rubber foam is a crosslinked urethane foam.

  The track pad according to a fifth aspect of the present invention is the track pad according to the fourth aspect, wherein the crosslinked urethane foam is formed using at least a polyether polyol and an MDI isocyanate as a urethane raw material.

  The track pad according to a sixth aspect of the present invention is the track pad according to any one of the first to fifth aspects, wherein the both ends of the pad main body protrude to the opposite side of the tie plate, and the protruding portion is reinforced. A reinforcing part is provided.

  In the track pad according to the present invention, the pad main body constituted by the rubber-like foam and interposed between the rail and the tie plate has protrusions protruding downward from both ends in the rail longitudinal direction. Yes. By engaging these protrusions with the end surfaces of the tie plate in the rail longitudinal direction, the track pad according to the present invention can be made difficult to drop off from the tie plate.

  In addition, even if the track pad according to the present invention is displaced with respect to the tie plate due to expansion and contraction due to the cold and warm of the rail, the pad body is restored even if the protruding part of the pad body is deformed due to interference with the tie plate or the like. Since it is composed of a rubber-like foam having good properties, it contributes to preventing or suppressing the destruction or permanent deformation of the pad main body. As a result, the track pad according to the present invention contributes to being reusable even if the track pad is dropped from the tie plate due to the above-described displacement.

  According to the present invention, it is possible to provide a track pad that is difficult to drop off from a tie plate and contributes to being reusable even if it drops off.

It is sectional drawing which looked at the track slab containing the track pad concerning the embodiment of the present invention from the rail longitudinal direction. It is a disassembled perspective view which decomposes | disassembles and shows a part of structure shown by FIG. It is a perspective view of a track pad concerning an embodiment of the present invention. It is a front view of a track pad concerning an embodiment of the present invention. It is a top view of a track pad concerning an embodiment of the present invention. It is a rear view of the track pad concerning the embodiment of the present invention. It is a right view of the track pad concerning the embodiment of the present invention. It is sectional drawing which shows the cut surface along the F8-F8 line | wire of FIG. It is sectional drawing which looked at a part of structure shown by FIG. 1 from the rail width direction, and is a figure corresponding to the F9-F9 line | wire of FIG. FIG. 10 is a cross-sectional view corresponding to FIG. 9 illustrating a state in which the track pad according to the embodiment of the present invention is displaced with respect to the tie plate. FIG. 10 is a cross-sectional view corresponding to FIG. 9 showing a state in which the track pad according to the embodiment of the present invention is displaced with respect to the tie plate in a manner different from that of FIG. 10A. It is a perspective view of a track pad concerning the 1st modification of an embodiment of the present invention. It is a front view of a track pad concerning the 1st modification. It is a top view of a track pad concerning the 1st modification. It is a rear view of the track pad concerning the 1st modification. It is a right view of the track pad concerning the 1st modification. It is sectional drawing which shows the cut surface along the F16-F16 line | wire of FIG. It is a perspective view of a track pad concerning the 2nd modification of an embodiment of the present invention. It is a front view of a track pad concerning the 2nd modification. It is a top view of the track pad concerning the 2nd modification. It is a rear view of the track pad concerning the 2nd modification. It is a right view of the track pad concerning the 2nd modification. It is sectional drawing which shows the cut surface along the F22-F22 line | wire of FIG. It is a top view which shows the partial structure of the track pad which concerns on the 3rd modification of embodiment of this invention. It is a top view which shows the partial structure of the track pad which concerns on the 4th modification of embodiment of this invention. It is a top view which shows the partial structure of the track pad which concerns on the 5th modification of embodiment of this invention. 10 is a front view of a track pad according to Comparative Example 3. FIG. 10 is a plan view showing a partial configuration of a track pad according to Comparative Example 3. FIG.

  Hereinafter, a track pad according to an embodiment of the present invention will be described with reference to the drawings.

The track pad 10 according to the present embodiment is a pad provided on a slab track, a direct connection track, or the like. The track pad 10 is a reference example.
Specifically, as shown in FIG. 1, the track slab is formed on, for example, a sleeper 20 arranged on a roadbed (not shown), a tie plate 22 fixed on the sleeper 20, and a tie plate 22. And a rail 24 to be fixed.

  Note that an arrow UP appropriately shown in each figure indicates an upward direction, an arrow L indicates a longitudinal direction of the rail 24 (hereinafter referred to as a rail longitudinal direction), and an arrow W indicates a width direction of the rail 24 (hereinafter referred to as a rail longitudinal direction). (Referred to as the rail width direction). Moreover, the “rail longitudinal orthogonal direction” described in the following description is a direction orthogonal to the rail longitudinal direction.

  The tie plate 22 is integrally provided with a plate main body 22A formed in a flat plate shape and a pair of protruding walls 22B for guiding the rail bottom 24A protruding upward from the upper surface of the plate main body 22A. The pair of projecting walls 22B stands up with an interval substantially equal to the width dimension of the bottom 24A of the rail 24, and the rail 24 is laid between these projecting walls 22B.

  In the tie plate 22, for example, both end portions of the plate body 22 </ b> A are fastened and fixed on the sleeper 20 by bolts 28 and nuts 30. The rail 24 is pressed and fixed on the plate body 22A by a pair of leaf springs 26 fastened and fixed to the pair of protruding walls 22B by bolts 32 and nuts 34, for example.

  For example, the rail 24 is fixed to the plate body 22 </ b> A through a variable pad 36 (for example, a resin injection type variable pad) and a track pad 10. The variable pad 36 is a pad for adjusting the rail height, and is a pad provided arbitrarily. The thickness dimension T4 of the variable pad 36 shown in FIG. 9 is set to 9 mm, for example.

  As described above, the track pad 10 according to the present embodiment is interposed between the rail 24 and the plate body 22 </ b> A of the tie plate 22. As shown in FIGS. 1 to 10, the track pad 10 is constituted by a rubber-like foam layer 12 that is a pad body, and has a required spring constant.

  The rubber-like foam layer 12 is composed of a rubber-like foam. The rubber-like foam layer 12 is formed in a substantially flat plate shape that is long in the rail longitudinal direction, and is disposed between the rail 24 and the variable pad 36 in a posture in which the plate thickness direction is along the vertical direction.

  The rubber foam layer 12 includes a flat portion 12A formed in a flat plate shape elongated in the longitudinal direction of the rail, and a pair protruding in the rail longitudinal direction (downward here) from both longitudinal ends 12A1 of the flat portion 12A. Projecting part (stop part: stopper part) 12B. For this reason, this rubber-like foam layer 12 is formed in the reverse concave shape (substantially reverse U-shape) opened to the downward side seeing from the rail width direction.

  The flat portion 12A is set such that a dimension W1 (see FIG. 4) in the rail width direction of the longitudinal intermediate portion 12A2 substantially coincides with the interval between the pair of protruding walls 22B, and the longitudinal intermediate portion 12A2 is a pair. It is sandwiched between the rail 24 and the variable pad 36 between the projecting walls 22B. The flat portion 12A has a length L1 in the rail longitudinal direction (see FIG. 5) longer than the length in the rail longitudinal direction of the tie plate 22, and both ends 12A1 in the longitudinal direction extend from the tie plate 22 to both sides in the rail longitudinal direction. Protruding.

  The both ends 12A1 in the longitudinal direction of the flat portion 12A are set to have a smaller dimension W2 (see FIG. 4) in the rail width direction than the intermediate portion 12A2 in the longitudinal direction. For this reason, the flat portion 12A is formed in a substantially cross shape (substantially X shape) when viewed in the vertical direction.

  On the other hand, the pair of projecting portions 12B projecting downward from the longitudinal end portions 12A1 of the flat portion 12A are opposed to the longitudinal direction of the rail with a gap slightly wider than the dimension of the tie plate 22 in the longitudinal direction of the rail. (See FIG. 9). These protrusions 12B protrude downward from the upper surface of the plate body 22A, and the variable pad 36 and a part of the plate body 22A are disposed between these protrusions 12B. A corner portion 12C between the protruding portion 12B and the flat portion 12A is formed in an arcuate curved surface when viewed from the rail width direction.

  The vertical dimension T1 (see FIG. 5) of the portion of the rubber foam layer 12 where the protrusion 12B is provided is set to, for example, about twice the vertical dimension T2 of the flat part 12A. Further, for example, these protrusions 12B have a rail width direction dimension W2 that matches the rail width direction dimension W2 at both longitudinal ends 12A1, and the rail length direction dimension L2 (see FIG. 5) is flat. It is set slightly smaller than the thickness dimension (vertical dimension) T2 of the portion 12.

  One projecting portion 12B is engaged with (in contact with or in close proximity to) one end surface of the variable pad 36 and the plate main body 22A in the rail longitudinal direction, and the other projecting portion 12B is composed of the variable pad 36 and the plate. The main body 22A is engaged (abutted or closely opposed) with the end face on the other side in the rail longitudinal direction. For this reason, the positional deviation in the rail longitudinal direction of the track pad 10 with respect to the tie plate 22 is regulated by these protrusions 12B.

  In the track pad 10 according to the present embodiment, the rubber foam layer 12 has a pair of projecting portions 12B that project downward from both end portions in the rail longitudinal direction. By engaging these protrusions 12B with both end surfaces of the tie plate 22 in the rail longitudinal direction, the track pad 10 can be made difficult to drop off from the tie plate 22 (see FIG. 9). As a result, the track pad 10 is blown off when passing through the vehicle and damages the vehicle, and a traffic signal failure occurs due to an insulation failure caused by the track pad 10 coming into contact with the insulating portion of the rail 24. Can be prevented or effectively suppressed.

  Further, as shown in FIG. 10A, due to the expansion and contraction of the rail 24 due to the temperature, the track pad 10 is displaced with respect to the variable pad 36 and the tie plate 22, and the protrusion 12B of the rubber foam layer 12 is the tie plate. Even if the rubber-like foamed layer 12 is deformed due to the interference with the variable pad 22 or the variable pad 36, the rubber-like foamed layer 12 can be prevented from or suppressed from being destroyed or permanently deformed by the good resilience of the rubber-like foamed layer 12. As a result, the track pad 10 contributes to being reusable even if the track pad 10 is dropped from the tie plate 22 due to the above-described displacement. In addition, as shown in FIG. 10B, the variable pad 36 may follow the track pad 10 and be displaced with respect to the tie plate 22. In such a case, the protruding portion 12B is deformed obliquely, but even in such a case, the same effect as described above can be obtained.

  In the present embodiment, the corner portion 12C between the protruding portion 12B and the flat portion 12A is formed in a curved surface shape. As a result, when the track pad 40 is displaced with respect to the tie plate 22 due to expansion and contraction due to the temperature of the rail 24 and the one protrusion 12B is deformed (see FIG. 10), the one protrusion 12B side It can suppress that stress concentrates on the corner part 12C. The radius of curvature R1 of the corner portion 12C is preferably in the range of 2 mm to 20 mm, and more preferably in the range of 5 mm to 10 mm. By setting the radius of curvature R1 within the range, it is possible to effectively prevent or suppress the destruction of the rubber-like foamed layer 12 due to the above-described position shift, and to ensure a good restorability after the position shift. can do.

  Furthermore, in this embodiment, the rubber-like foam layer 12 is provided as a pad body, so that the composition of the urethane raw material (isocyanate concentration, etc.), the foamed state (single foam) can be obtained without removing the meat like a rubber member. The spring constant of the desired track pad 10 can be easily controlled by adjusting the film thickness and the like, and the restorability, durability and wear resistance can be ensured.

  And since the pad main body of the track pad 10 is comprised with the rubber-like foam, it is possible to manufacture easily the special shape which does not fall easily from the tie plate 22 with a liquid raw material.

  In addition, you may make it the structure which laminates and forms the resin-made sliding layer (illustration omitted) on the surface at the side of the rail 24 of the rubber-like foaming layer 12. FIG. Since the sliding layer made of resin is interposed between the rail 24 and the rubber foam layer 12, the slidability of the track pad 10 with respect to the rail 24 is enhanced, so that the track pad 10 is difficult to drop off from the tie plate 22. Contributes to Moreover, separation of the sliding layer and the rubbery foam layer 12 can be prevented or effectively suppressed by selecting a resin constituting the sliding layer that has high adhesiveness with the rubbery foam layer 12. It becomes possible. As a result, the service life can be extended, and the track pad 10 can be made difficult to be detached from the rail 24 even when the cutting force due to the expansion and contraction of the rail 24 and the vibration due to passing through the vehicle are loaded.

  Further, the rail length dimension L2 of the protrusion 12B is about 100% to 150% of the thickness dimension of the flat portion 12A, and it is difficult to drop from the tie plate 22, and the protrusion 12B is reinforced to make it difficult to drop. It is also preferable to provide a reinforcing portion (reinforcing rib) to be used. In addition, the rail width direction dimension W2 of the protruding portion 12B is preferably about 50% or more of the width dimension of the rail 24 and about 120% at the maximum, and is larger than the distance between the pair of projecting walls 22B in the rail width direction. You can enlarge it. Further, the thickness dimension T3 of the protruding portion 12B is preferably equal to the plate thickness of the plate main body 22A, and the larger the larger, the more difficult it is to drop from the tie plate 22.

  Moreover, the shape of the track pad according to the present invention is not limited to the shape of the track pad 10 shown in FIGS. 1 to 10B, and can be changed as appropriate according to the manner of intervention in the track slab.

  For example, the shape of the rubber-like foam layer 12 may be set like a track pad 40 (first modification) shown in FIGS. In the track pad 40, a plurality of reinforcing ribs (reinforcing portions) 12D aligned in the rail width direction are integrally formed at both ends in the longitudinal direction of the rubber foam layer 12. These reinforcing ribs 12D protrude to the opposite side of the tie plate 22 when the track pad 40 is interposed between the rail 24 and the tie plate 22, and each protrusion 12B is opposite to the tie plate 22. Reinforce from the side. Since these reinforcing ribs 12D can suppress the bending of the protruding portion 12B with respect to the flat portion 12A, the difficulty of falling off from the tie plate 22 can be improved.

  In the track pad 40, a curved chamfered portion 12E is formed on the lower end side of each reinforcing rib 12D. The portions where the chamfered portions 12E are formed are opposite to the rails 24 at both ends of the rubber foam layer 12 in the rail longitudinal direction when the track pad 40 is interposed between the rail 24 and the tie plate 22. This is a part located on the side opposite to the tie plate 22. For this reason, when the track pad 40 that is displaced with respect to the tie plate 22 is returned to the normal position (see FIG. 9) due to the expansion and contraction of the rail 24, the one chamfered portion 12E becomes the variable pad 36 or the plate. By making sliding contact with the main body 22A, the track pad 40 is easily returned to the normal position. The radius of curvature R2 of the chamfered portion 12E is preferably in the range of 5 mm to 20 mm, and more preferably in the range of 10 mm to 15 mm.

  Further, for example, the shape of the rubber foam layer 12 may be set like a track pad 50 (second modified example) shown in FIGS. In this track pad 50, unlike the track pad 40 according to the first modification, the reinforcing ribs 12D are not divided into a plurality in the rail width direction, and the reinforcing ribs 12D are integrally connected in the rail width direction. Also in this second modification, the same operational effects as in the first modification can be obtained.

The shape of the reinforcing rib 12D is not limited to that of the track pads 40 and 50, and can be changed as appropriate. For example, as the track pad 60 (third modified example) shown in FIG. 23 and the track pad 70 (fourth modified example) shown in FIG. 24, the reinforcing ribs 12D go upward as viewed from the rail width direction. You may make it the structure formed in the taper shape which becomes thick in a rail longitudinal direction. Further, like the track pad 80 (fifth modified example) shown in FIG. 25, the reinforcing rib 12D may be formed in an arc shape when viewed from the rail width direction. The shape of the reinforcing rib 12D as shown in FIG. 11 to FIG. 25 is difficult to manufacture unless it is a raw material with good fluidity, but it is preferable to use a crosslinked urethane-based foaming raw material because it can be molded even with a complicated shape. The fourth modification is a reference example.

  Hereinafter, the details of the constituent layers of the above-described track pads 10, 40, 50, 60, 70, 80 will be described. In the following description, reference numerals are omitted as appropriate.

(Rubber foam layer)
The rubber-like foam layer corresponds to the spring of the track pad, and is a layer that particularly requires a restoring property. And in order to satisfy | fill a characteristic, the said layer is comprised with the rubber-like foam.

The rubber-like foam has a required spring constant (for example, 15 to 60 MN / m). The rubber-like foam preferably has a density of 0.50 to 0.90 g / cm ³ and an elongation of 130% or more. The lower the density, the harder it is to scratch the track pad even if the rail is pulled out, but the pull-out strength is low and the required spring constant is difficult to obtain. Conversely, if the density is high, it will be difficult to fall off, but it will be easily damaged when coming off the rail. On the other hand, if the elongation is less than 130%, the track pad is likely to be torn off when it comes off the rail.

In other words, when the density and elongation of the rubber foam are in the above ranges, even if the track pad falls off the rail, the track pad is less likely to be damaged. From the same point, the rubber-like foam has a density of 0.60 to 0.90 g / cm ³ and more preferably an elongation of 150 to 400%, and a density of 0.70 to 0.90 g / cm ^3. More preferably, it is cm ³ and the elongation is 160 to 300%.

  Examples of rubber-like foams include: 1) Molded bodies formed by using natural rubber, SBR (styrene butadiene), EPDM (ethylene propylene diene rubber) and other general-purpose rubbers together with a foaming agent and a vulcanizing agent. 2) A molded article obtained by adding a foaming agent to a thermoplastic elastomer and foam-molding by a method such as injection foaming. As the foaming agent, for example, a general-purpose foaming agent such as azodicarbonamide (ADCA), sodium hydrogen carbonate, sodium citrate or the like is used alone or in combination, or foamed microcapsules are used.

  Furthermore, examples of the rubber-like foam include urethane foams (particularly crosslinked urethane foams) formed by foaming using a liquid raw material.

Among these rubber-like foams, a crosslinked urethane foam is preferable in terms of obtaining various characteristics of the track pad. In particular, the crosslinked urethane foam has an advantage in that it can be formed into a complicated shape such as an uneven shape or a shape whose thickness changes.
Hereinafter, the rubber-like foam layer composed of the crosslinked urethane foam is also referred to as “crosslinked urethane foam layer”.

  For example, the crosslinked urethane foam can be obtained by, for example, 1) a method of injecting a mixed stock solution containing a polyol, an isocyanate, a foaming agent, and, if necessary, a chain extender into a mold as a urethane raw material, and 2) separating the mixed stock solution. It can be formed by a method in which it is applied to a pattern paper, heat-cured, and then punched into a predetermined shape. The mixed stock solution containing the urethane raw material contains a foaming agent and may contain other additives.

-Polyol-
As the polyol, for example, a polyether-based polyol such as polyoxypropylene polyol (PPG), polyoxyethylene polyol (PEG), a copolymer of PPG and PEG, or polyoxytetramethylene polyol (PTMG) is preferably used. Since polyether polyols (particularly PPG and PTMG) are excellent in hydrolysis resistance as well as reactivity, durability and resilience of the crosslinked urethane foam are likely to increase. In addition, polyether polyols have the advantage of low viscosity and high handleability.

  In addition to polyether polyols, polyols include dicarboxylic acids (adipic acid, sebacic acid, phthalic acid, dimer acid, etc.) and glycols (ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 2 Polyester polyol (PES), polycaprolactone polyol (PCL), polycarbonate polyol (PCA), (hydrogenated) polybutadiene-based polyol, (hydrogenated) polyisoprene condensed with -methylpropanediol, 3-methylpentanediol, etc. A system polyol or the like may also be used.

  In addition, it is preferable that the polyol is preliminarily reacted with an excess equivalent of isocyanate to be used as a prepolymer of a terminal NCO group because the restorability and toughness of the crosslinked urethane foam are increased.

-Isocyanate-
As the isocyanate, for example, toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), or crude MDI (cr-MDI) is preferably used. In particular, it is preferable to use diphenylmethane diisocyanate (MDI) -based isocyanate because the reactivity is high and the durability and resilience of the crosslinked urethane foam are easily increased.

-Chain extender-
Examples of the chain extender include aromatic diamines (for example, 4,4′-diamino-3,3′-dichlorodiphenylmethane (MOCA)), glycols having a molecular weight of 500 or less, or polyfunctional alcohols (for example, ethylene glycol, 1,4-butane). Diol, 1,6-hexanediol, trimethylolpropane, glycerin, trimethylolpropane, etc.) and their ethylene oxide adducts or propylene oxide adducts, bisphenol A ethylene oxide adducts or propylene oxide adducts, hydroquinone ethylene oxide It is preferable to use an adduct, an ethylene oxide adduct of resorcin.

  Among these, the chain extender is a low molecular polyol of a primary alcohol having a molecular weight of 200 or less, and ethylene oxide addition of ethylene glycol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, hydroquinone, resorcin. A thing etc. are the most preferable.

-Foaming agents and other additives-
As other additives, well-known additives such as a catalyst and a foam stabilizer are used in addition to the foaming agent.
As the blowing agent, for example, water, a low-boiling organic solvent (such as cyclopentane or dichloromethane), a halogenated hydrocarbon, a mixture thereof, or the like is used. In addition, the foaming of urethane can also take the method of enclosing a bubble using polyol or a prepolymer using air or nitrogen.
As the catalyst, for example, an amine-based catalyst or a tin-based metal catalyst is used.
As the foam stabilizer, for example, a silicone compound represented by a copolymer of polydimethylsiloxane and polyoxyalkylene polyol is used.

-Introducing urethane crosslinking-
In order to introduce crosslinking into urethane, it is preferable to use a bifunctional or higher functional polyol in any of polyol, isocyanate, and chain extender. In particular, when a terminal NCO group polyol prepolymer is used, in order to introduce crosslinking into urethane, the terminal NCO group polyol prepolymer is bifunctional and the chain extender is bifunctional or more. It is preferable to use an isocyanate together or to use these together because the prepolymer can be easily synthesized and the viscosity can be reduced.

-Other aspects-
The rubber-like foam may be a closed-cell foam. When the bubbles of the rubber-like foam are closed cells, the layer is difficult to absorb water and the durability is easily increased.
The tensile strength of the rubber-like foam is, for example, 5 to 20 MPa, preferably 7 to 15 MPa.
The expansion ratio of the rubber-like foam is, for example, preferably 1.1 to 2.3 times, and preferably 1.1 to 1.6 times.

-Thickness of rubber foam layer-
The thickness of the rubber foam is, for example, 1 to 15 mm, preferably 3 to 13 mm.

(Sliding layer)
The sliding layer is a surface layer that is in direct contact with the rail, and must have a hardness that prevents the track pad from shifting due to expansion and contraction of the rail, and also needs to be a slippery surface.
For this reason, the sliding layer is preferably composed of a resin layer having a static friction coefficient of 0.35 or less. The lower limit value of the static friction coefficient varies depending on the fastening force of the track pad, but is about 0.15, for example.

  Examples of the resin layer having a static friction coefficient of 0.35 or less constituting the sliding layer include urethane resin, polyolefin resin (for example, polyethylene resin, polypropylene resin, etc.), nylon resin (6 nylon resin, 66 nylon resin), polyoxymethylene. Examples of the resin layer include resin, polyethylene resin (for example, polyethylene terephthalate resin), and ebonite. The ebonite resin layer is preferable because it can be integrally bonded when the rubber-like foam layer is formed. In addition, an olefin resin layer such as a polyethylene resin or a polypropylene resin is preferable because it can be bonded simultaneously when a rubber-like foam layer, which is a foam molded body of an olefin thermoplastic elastomer, is formed.

  On the other hand, the above-mentioned resin layer can be reactively bonded to the crosslinked urethane foam layer by utilizing the good adhesiveness of the urethane raw material when forming the crosslinked urethane foam layer. In that case, these resin layers are formed into a sheet in advance, and the surface is preliminarily mechanically roughened (polished, blasted, etc.), oxidized (corona discharge, plasma treated, etc.), or easily adhered by primer treatment. It is preferable to give. In addition, these resin layers may be bonded using a crosslinked urethane foam layer and an adhesive, which are previously formed into a sheet shape and produced.

Among these resin layers as the sliding layer, the urethane resin layer is most preferable because it has good adhesion because it is the same type of resin as the rubber foam layer that is a crosslinked urethane foam. Further, a resin layer of high-density polyethylene, 6 nylon, or 66 nylon is preferable because it is easy to react and bond when a crosslinked urethane foam layer is formed by surface treatment.
Note that a resin layer of high-density polyethylene, 6 nylon, or 66 nylon has a low coefficient of static friction and is preferable from the viewpoint of excellent compatibility in a use environment as a track pad, long-term durability, and wear resistance.

As the high density polyethylene, polyethylene having a density of 0.94 to 0.97 g / cm ³ is used. High density polyethylene of this density can be used satisfactorily because the sliding layer is good and the coefficient of static friction is low and tough. In particular, it is preferable to use a high-density polyethylene having a viscosity average molecular weight (ASTMD 2857) of 5 to 6 million called ultrahigh molecular weight polyethylene, because the durability and wear resistance of the sliding layer become extremely high. In addition, when a sheet made of ultra-high molecular weight polyethylene is roughened and / or surface-treated with corona discharge as this high-density polyethylene, the adhesion to the crosslinked urethane foam layer is also better than that of a normal high-density polyethylene sheet. preferable.
General-purpose grades can be used for 6 nylon and 66 nylon, but an impact resistant grade in which an olefin elastomer is blended with nylon can also be used.

  The thickness of the sliding layer is preferably 0.05 to 2.5 mm, and particularly preferably 0.2 to 1.0 mm from the viewpoint of durability and workability.

(Mode without sliding layer)
A sliding layer is a layer provided as needed. In this case, the track pad is composed of a single layer of a rubber foam layer. That is, the rubber-like foam layer is a layer that is in direct contact with the rail and needs to be a slippery surface so that the track pad does not shift due to the expansion and contraction of the rail.

  For this reason, when the sliding layer is not provided, the rubbery foam layer preferably has a static friction coefficient of 0.35 or less. The lower limit value of the static friction coefficient varies depending on the fastening force of the track pad, but is about 0.15, for example.

  In order to make the static friction coefficient of the rubber-like foam layer 0.35 or less, the composition of the rubber-like foam layer may be adjusted, but the rubber-like foam layer may contain a slidability improving material.

  As the sliding property improving material, for example, a sliding powder made of silicone resin powder, fluororesin powder, high density polyethylene powder, ultrahigh molecular weight polyethylene powder, polypropylene powder, polyoxymethylene powder, graphite powder, molybdenum disulfide powder is used. . In addition to the slidability improving material, a liquid silicone oil, a foot coat compound, a metal soap or the like may be used in combination as a slidability improving aid.

  When the cross-linked urethane foam layer is applied as the rubber-like foam layer, the slidability improving material may use a silicone compound having an active hydrogen group in the molecule. This silicone compound having an active hydrogen group in the molecule is blended in a urethane raw material and reacted with an isocyanate. The silicone compound as the slidability improving material reacts with the isocyanate to lower the static friction coefficient of the crosslinked urethane foam layer. Moreover, the water absorption rate of a crosslinked urethane foam layer can be reduced.

Examples of the silicone compound having an active hydrogen group in the molecule include an OH group, an NH group, an NH ₂ group, a mercapto group, or a silicone compound having two or more of these groups on at least one of a terminal and a side chain of polydimethylsiloxane. Can be mentioned.

  Of these silicone compounds having an active hydrogen group in the molecule, silicone compounds having an OH group in the molecule are most preferred. The silicone compound having an OH group in the molecule has an advantage that it is easy to produce a crosslinked urethane foam layer because the reactivity with the urethane raw material is about the same in terms of speed.

  Examples of the silicone compound having an active hydrogen group in the molecule also include polydimethylsiloxane-terminal OH group polyalkylene ether-graft copolymer. When this silicone compound is used for producing a crosslinked urethane foam layer, it functions as a silicone foam stabilizer and can control the static friction coefficient of the crosslinked urethane foam layer.

  Silicone compounds having active hydrogen groups in these molecules melt well in the urethane raw material, but at the same time as the reaction proceeds, they bleed on the surface and eventually are unevenly distributed on the surface of the layer, which is effective in reducing the friction coefficient. In addition, since it is incorporated into the composition, it does not elute, and long-term effects are easily maintained.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following description, unless otherwise specified, “part” and “%” relating to the blending amount (content, addition amount) are based on mass.

(Example 1-1)
To 100 parts of a prepolymer consisting of 100 parts of PTMG 1000 (PTMG manufactured by Mitsubishi Chemical Corporation, molecular weight 1000) and 60.87 parts of Millionate P-MDI (Pure MDI manufactured by Nippon Polyurethane Co., Ltd.), 11.1 parts of Millionate P-MDI, 1, 4 -Butanediol / trimethylolpropane (75/25) 10.94 parts, water 0.1 parts, dibutyltin dilaurate 0.03 parts as a catalyst, and foam stabilizer SH-193 (manufactured by Toray Dow Corning) 0 .5 parts were mixed with stirring. A predetermined amount of this foaming stock solution was poured into a predetermined mold and the mold was closed. After 5 minutes, it was cured by heating in an oven at 100 ° C for 10 minutes. Thereafter, the product was demolded, and a product composed of a single layer of a crosslinked urethane foam layer was taken out.
In this way, a track pad 10 of the type shown in FIGS. 1 to 10 was manufactured. In this track pad 10, W1 shown in FIG. 4 is set to 140 mm, W2 is set to 80 mm, W3 is set to 30 mm, L1 shown in FIG. 5 is 232 mm, L2 is 10 mm, T1 is 24 mm, T2 was set to 10.8 mm and T3 was set to 13.2 mm. Moreover, in this track pad 10, the tie plate contact surface dimension (here, the dimension of the contact surface with the variable pad 36) was set to 178 mm long × 140 mm wide. Moreover, in this track pad 10, the radius of curvature R1 of the corner portion 12C was set to 5 mm, and the radius of curvature R2 of the chamfered portion 12E was set to 12 mm. These radii of curvature R1 and R2 were similarly set in other examples and comparative examples described below.

(Example 1-2)
A track pad 40 of the type shown in FIGS. 11 to 16 was manufactured in the same manner as in Example 1-1 except that the mold was changed. In this track pad 40, W1 shown in FIG. 12 is set to 140 mm, W2 is set to 80 mm, W3 is set to 30 mm, W4 is set to 11 mm, and L1 shown in FIG. 13 is set to 260 mm. L2 was set to 10 mm, L3 was set to 24 mm, T1 was set to 24 mm, T2 was set to 10.8 mm, and T3 was set to 13.2 mm. Moreover, in this track pad 10, the tie plate contact surface dimension was set to length 178 mm x width 140 mm.

(Example 1-3)
A track pad 50 of the type shown in FIGS. 17 to 22 was manufactured in the same manner as in Example 1-1 except that the mold was changed. In this track pad 50, W1 shown in FIG. 18 is set to 140 mm, W2 is set to 80 mm, W3 is set to 30 mm, L1 shown in FIG. 19 is set to 260 mm, and L2 is set to 10 mm. L3 was set to 24 mm, T1 was set to 24 mm, T2 was set to 10.8 mm, and T3 was set to 13.2. Moreover, in this track pad 10, the tie plate contact surface dimension was set to length 178 mm x width 140 mm.

(Example 1-4)
In the same manner as in Example 1-3, except that Millionate P-MDI / Millionate M-200 (weight ratio = 1/1) was used in place of Millionate P-MDI in a weight ratio of 1/15, FIG. A track pad 50 of the type shown in FIG. 22 was produced.
Millionate P-MDI (Pure MDI manufactured by Nippon Polyurethane Co., Ltd.) is a bifunctional isocyanate, and Millionate M-200 (manufactured by Nippon Polyurethane Co., Ltd.) is an isocyanate having a number of polyfunctional groups.

(Example 1-5)
A track pad 50 of the type shown in FIGS. 17 to 22 in the same manner as in Example 1-3, except that 12 parts of Millionate M-200 (manufactured by Nippon Polyurethane Co., Ltd.) were used instead of Millionate P-MDI. Was made.

(Example 1-6)
Except having adjusted the quantity of water as a foaming agent, it is the same as Example 1-4, and the density of a crosslinked urethane foam is 0.92 g / cm < ³ >, The track pad of the type shown by FIGS. 50 were made.

(Example 2)
-Production of urethane resin sheet-
To 140 parts of prepolymer consisting of 100 parts of PTMG650 (Mitsubishi Chemical Polytetramethylene Glycol, Molecular Weight 650) and 158 parts of Millionate P-MDI (Diphenylmethane Diisocyanate, Nippon Polyurethane). 23 parts of 14-butanediol and 0.05 part of dibutyltin dilaurate as a catalyst were stirred. This raw material liquid was applied to a thickness of about 1 mm on a silicone release-treated polyester film, and heated and cured at 100 ° C. for 10 minutes to obtain a urethane resin sheet. The obtained urethane resin sheet had a thickness of 1.2 mm, an A hardness of 97, a static friction coefficient of 0.25, an abrasion amount of 2 mg, and was extremely tough.

-Fabrication of track pad-
Except that the urethane resin sheet was laid on the upper surface of the mold, it was composed of a laminate of a sliding layer made of a urethane resin sheet and a crosslinked urethane foam layer, in the same manner as in Example 1-3. A track pad 50 of the type shown in FIG.

(Example 3)
A slide made of an ultrahigh molecular weight polyethylene resin sheet in the same manner as in Example 2 except that an ultrahigh molecular weight polyethylene resin sheet (manufactured by Sakushin Kogyo Co., Ltd.) having a thickness of 0.13 mm was used instead of the urethane resin sheet. A track pad 50 of the type shown in FIGS. 17 to 22 was made of a laminate of a layer and a crosslinked urethane foam layer.

(Comparative Example 1)
Except for changing the mold, a track pad having an overall size and a tie plate contact surface size of 178 mm long × 140 mm wide × 24 mm thick was prepared in the same manner as in Example 1-1. This track pad is a pad configured only by the flat portion 12A in the track pad 10.

(Comparative Example 2)
A track pad 100 of the type shown in FIGS. 26 to 27 was manufactured in the same manner as in Example 1-1 except that the mold was changed. In the track pad 100, the protruding portions 12B are protruded from both longitudinal ends 12A1 of the flat portion 12 to both sides in the rail width direction. Moreover, the thickness dimension T6 of these protrusion part 12B and longitudinal direction both ends 12A1 was set smaller than the thickness dimension T5 of the flat part 12. FIG. In this track pad 100, W1 shown in FIG. 26 is set to 140 mm, W5 is set to 15 mm, W6 is set to 170 mm, L1 is set to 260 mm, and L4 shown in FIG. 27 is set to 30 mm, T5. Was set to 12 mm, and T6 was set to 7 mm. Moreover, in this track pad 10, the tie plate contact surface dimension was set to length 178 mm x width 140 mm.

(Comparative Example 3)
It is composed of a single layer of a crosslinked urethane foam layer reinforced with glass fibers in the same manner as in Comparative Example 2, except that a glass mat (manufactured by Nittobo Co., Ltd.) having a basis weight of 1000 g / m ² is laid on the lower surface of the mold. A track pad 100 of the type shown in FIGS. 26 to 27 was manufactured.

(Comparative Example 4)
A track pad (Shin Nihon Eslite, trade name EB material track pad) in which ebonite was stacked on the surface of non-foamed natural rubber (rubber-like non-foamed layer) on which ebonite was stacked was prepared. This track pad was set in the same shape as the track pad 100 of the type shown in FIGS.

Example 4
5 parts of polyethylene masterbatch of heat-expandable microcapsules (Matsumoto Microsphere FN180SS, manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) was mixed with 100 parts of Infuse 9530 (MFR 5, manufactured by Dow Chemical Co., Ltd.) which is an olefinic thermoplastic elastomer. . This mixture was put into a hopper of an injection molding machine (Nippon Steel Works), and a 0.5 mm polypropylene resin sheet was set in advance in a mold, and injected at a resin temperature of 200 ° C. and foamed by a core back method to be molded.
Thereby, a track pad constituted by a laminate of a sliding layer made of a polypropylene resin sheet and a rubbery foam layer made of a foam of an olefinic thermoplastic elastomer was produced.
In addition, the track pad was shape | molded in the same shape as Example 1-1 (refer FIGS. 1-10). Here, when the rubber-like foam layer was observed, it was observed that the rubber filling property of the pair of protrusions (stop portion: stopper portion) was poor.

(Example 5)
100 parts of EPDM rubber (E552 manufactured by Sumitomo Chemical Co., Ltd.), 50 parts of seast 116 (carbon black manufactured by Tokai Carbon Co., Ltd.), 60 parts of Diana Process Oil PW32 (paraffinic process oil manufactured by Idemitsu Kosan Co., Ltd.), 5 parts of zinc white, 1 of stearic acid Part, vulcanization accelerator Noxeller TS (manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1.5 parts, vulcanization accelerator Noxeller M (manufactured by Ouchi Shinsei Chemical Co., Ltd.) 0.5 parts, sulfur 1.5, expanded foam microcapsules 10 parts of MFL-100MCA (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) was put into a pressure kneader and kneaded for 20 minutes. An ebonite unvulcanized sheet (2.0 mm) was placed on the mold, and the above-mentioned kneaded rubber sheet was charged and vulcanized and foamed at 160 ° C. for 15 minutes.
Thereby, a track pad constituted by a laminate of a sliding layer made of an ebonite sheet and a rubbery foam layer made of a foam of EPDM rubber was produced.
In addition, the track pad was shape | molded in the same shape as Example 1-1 (refer FIGS. 1-10). Here, when the rubber-like foam layer was observed, it was observed that the rubber filling property of the pair of protrusions (stop portion: stopper portion) was poor.

(Evaluation)
In addition to measuring the physical properties of the track pads obtained in each example, various tests were performed for evaluation.

  Hereinafter, various measurement methods and various tests performed in this example will be described. In addition, the various values of this invention are values measured by the measuring method shown below.

(Measuring method)
-Density-
The density was determined by measuring the weight of the test piece in terms of weight and volume, and the formula: density = weight ÷ volume.

-Foaming magnification-
The expansion ratio was obtained from the raw material specific gravity before foaming and the density after foaming by the formula: foam expansion ratio = raw material specific gravity ÷ foaming density.

-Tensile strength, elongation, spring constant-
The tensile strength, elongation, and spring constant were measured according to JISE1117.

-Static friction coefficient-
The static friction coefficient is in accordance with JISK7125. A test piece (30 mm × 30 mm × thickness) of a track pad is placed on a steel plate, and a weight with a load of 200 g is placed on the test piece. One end of the test piece was pulled at a speed of 50 mm / min, and the initial maximum load was divided by the load (200 g).

(Dropping test: Maximum pull-out load, presence or absence of breakage)
The track pad obtained in each example was fixed to the lower surface of a 60 kg rail with an adhesive. Next, the rail to which the track pad was fixed was placed on a variable pad (thickness 9 mm) placed on a straight 8-tie plate with the track pad as the bottom surface. Next, the tie plate was fixed to the sleeper with a predetermined torque (the bolt axial force was set to 7 kN) with straight 8 fastening springs and bolts. In this state, a load is applied at a constant speed by a hydraulic pump from one side of the rail, and the track pad bonded to the rail is moved until it is pulled out of the tie plate. At this time, the load applied to the rail was continuously measured, and the maximum load value was defined as the “maximum pull-out load”. We also observed whether or not the track pad after breaking out was destroyed.

(Comprehensive evaluation)
Comprehensive evaluation was evaluated according to the following criteria.
A (◯): The shape was good, and even in the drop-off test, the maximum pulling load was high, and the track pad was not broken.
B ((triangle | delta)): The shape pad or the crack of the track pad was seen by the drop-off test.
C (x): In the drop-off test, the maximum pull-out load was low or the track pad was broken.

  Tables 1 and 2 list the physical property measurement results and various test results together with details of each example.

From the above results, it can be seen that the track pad of this example has a high maximum pull-out load in the drop-off test, and the destruction of the track pad is also suppressed.
Thus, it can be seen that the track pad of the present embodiment is not easily dropped from the tie plate, and can be reused even if it is dropped.

10 Track pad 12 Rubber foam layer (pad body)
12B Protruding part 12D Reinforcement rib (reinforcement part)
12E Chamfered part 22 Tie plate 24 Rail 40 Track pad 50 Track pad 60 Track pad 70 Track pad 80 Track pad

Claims (6)

A pad body made of rubber foam and interposed between the rail and the tie plate has protrusions protruding downward from both ends in the rail longitudinal direction, and each of the protrusions is the tie plate. The track pad is engaged with the end surface of the rail in the longitudinal direction of the rail, and has a chamfered portion on the opposite side of the pad body on the opposite side of the rail and on the opposite side of the tie plate.   The track pad according to claim 1, wherein the rubber-like foam has a density of 0.50 to 0.90 g / cm3 and an elongation of 130% or more.   The track pad according to claim 1 or 2, further comprising a resin layer that is laminated on a surface of the pad body on the rail side and has a static friction coefficient of 0.35 or less.   The track pad according to any one of claims 1 to 3, wherein the rubber-like foam is a crosslinked urethane foam.   The track pad according to claim 4, wherein the crosslinked urethane foam is formed using at least a polyether polyol and an MDI isocyanate as a urethane raw material.   The track pad according to any one of claims 1 to 5, wherein a reinforcing portion that reinforces the protruding portion is provided at the both end portions of the pad main body.

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