Brake pads for rail brakes

Abstract

The present invention provides a rail brake pad made of metal, suitable for the operating conditions of rail brakes, which exhibits a moderately high braking force at the initial stage of braking, and then gradually increases the braking force while remaining stable until braking is completed, and uses a friction material with high physical strength. [Solution] The brake pad 1 for rail brakes of the present invention is attached to the lower surface 10a of the back plate 10 and has a friction material 2 based on metal, and the friction material 2 is composed of a metal component 6 and a ceramic material.

Description

Technical Field

[0001] The present invention relates to a brake pad for a rail brake that is suitably used for a rail brake of a crane or the like that moves on rails.

Background Art

[0002] Conventionally, various rail brakes have been proposed for cranes that move on rails (for example, port cargo handling cranes that perform container cargo handling in ports and the like) to prevent the crane from being swept by strong winds and running away.

[0003] As brake pads used for this type of rail brake, brake pads having a higher friction coefficient are required in order to improve braking force and holding force, and metal-based brake pads are provided as brake pads having a higher friction coefficient.

[0004] However, although a brake pad that simply has a high friction coefficient can exert braking force, sudden braking occurs when the brake is applied, which raises a concern that it may cause the collapse of the crane. Therefore, as a brake pad for a rail brake, an ideal friction material is one that exerts a moderately high braking force in the initial stage of braking, and then stabilizes and gradually increases the braking force to complete braking. In addition, for large cranes, a very large load is applied to the friction material when the brake is actuated, so it is also necessary for the friction material to have high physical strength.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0006] Therefore, the object of the present invention is to provide a rail brake pad made of metal that is suitable for the operating conditions of rail brakes, which exhibits a moderately high braking force in the initial stages of braking, and thereafter the braking force gradually increases steadily until braking is completed, and which uses a friction material with high physical strength. [Means for solving the problem]

[0007] To solve the above problems, a brake pad for a rail brake is provided, which has a friction material attached to the lower surface of a back plate and is based on metal, and the friction material is composed of a mixture of metal components and ceramic materials (Claim 1).

[0008] The friction material is preferably composed of a lubricating component (Claim 2). The metal component is preferably composed of 60-70% by weight, the ceramic material of 20-25% by weight, and the lubricating component of 5-15% by weight (Claim 3). The metal component is preferably composed of copper, iron, nickel, or chromium, or a composite of two or more of these (Claim 4). The ceramic material is preferably composed of SiC, zircon sand, or mullite, or a composite of two or more of these (Claim 5). The lubricating component is preferably composed of graphite material and / or molybdenum sulfide (Claim 6). The friction material is preferably configured to have a coefficient of friction of 0.25-0.45 (Claim 7). The friction material is preferably configured to have a bending strength of 10-100 MPa (Claim 8). The friction material is preferably configured to have a bulk density of 4.0-8.0 (Claim 9). The brake pad for the rail brake preferably has a rust-preventive layer covering the friction material, and the rust-preventive layer is preferably made of a ceramic material (Claim 10). [Effects of the Invention]

[0009] According to the rail brake pad described in claim 1, the rail brake pad is made of metal and is suitable for the operating conditions of a rail brake, and is configured to exert a moderately high braking force in the initial stages of braking, and thereafter the braking force gradually increases steadily until braking is completed, and is made of a friction material with high physical strength.

[0010] According to the brake pad for rail brakes described in claim 2, the sliding properties of the friction material are enhanced, and more stable braking force can be achieved.

[0011] The brake pad for rail brakes described in claim 3 can be configured to provide a brake pad for rail brakes that better achieves the effects of claim 1. Specifically, if the metal component is less than 60% by weight, the strength will be insufficient, and the brake material may deform or break under the load during braking. If it is more than 70% by weight, the metallic properties will be too pronounced, and if copper is the base material, malleability and ductility will be increased, which may cause the brake material to deform or break under the load during braking. Furthermore, if the ceramic material is less than 20% by weight, the grinding performance will be insufficient, and the expected frictional force will not be obtained. If it is more than 25% by weight, the grinding performance will be excessive, attacking and damaging the mating surface (rail). In addition, if the lubricating component is less than 5% by weight, the sliding properties will be poor, and the frictional resistance of the sliding surface will be high, resulting in unstable braking force. If it is more than 15% by weight, the coefficient of friction will be low, and the braking force will decrease.

[0012] The brake pad for rail brakes described in claim 4 can be configured to provide a rail brake pad that better achieves the effects of claim 1. Specifically, copper and iron serve as the base material for the friction material, and the strength of the friction material can be increased by alloying them with nickel and chromium through compounding and sintering.

[0013] The brake pad for rail brakes described in claim 5 can be configured to provide a brake pad for rail brakes that better achieves the effects of claim 1. Specifically, the frictional force during braking can be increased by the abrasive properties of SiC, zircon sand, or mullite.

[0014] The brake pad for rail brakes described in claim 6 can be configured to provide a brake pad for rail brakes that better achieves the effects of claim 1. Specifically, since graphite or molybdenum sulfide has lubricating properties on its own, by incorporating an appropriate amount, sliding properties can be added to the friction material.

[0015] The brake pad for rail brakes described in claim 7 can be configured to provide a brake pad for rail brakes that better achieves the effects of claim 1. Specifically, if the coefficient of friction of the friction material is less than 0.25, the force that applies the brakes and maintains the posture will be reduced, and if an external force greater than the frictional force is applied, the crane will move. If it is greater than 0.45, there is a possibility of damaging the opposing rail.

[0016] The brake pad for rail brakes described in claim 8 can be configured to provide a brake pad for rail brakes that better achieves the effects of claim 1. Specifically, if the bending strength of the friction material is less than 10 MPa, the strength of the friction material itself is low, and there is a risk that the brake material will be damaged due to the hydraulic load during braking. Also, if it is greater than 100 MPa, the friction material itself becomes very strong and hard, and there is a risk that it may damage the opposing rail.

[0017] The brake pad for rail brakes described in claim 9 allows for the construction of a brake pad for rail brakes that better achieves the effects of claim 1. Specifically, if the bulk density of the friction material is less than 4.0, sufficient bending strength cannot be obtained, and the necessary material strength of the friction material itself cannot be obtained. Also, if it is greater than 8.0, the material strength of the friction material becomes too high, which may cause damage to the opposing rail.

[0018] According to the brake pad for a rail brake according to claim 10, a brake pad for a rail brake provided with an effective rust preventive layer is configured. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] [Figure 1] FIG. 1 is a longitudinal sectional view of one embodiment of the brake pad for a rail brake of the present invention. [Figure 2] FIG. 2 is a schematic front view for explaining an example of use of the brake pad for a rail brake of the present invention. [Figure 3] FIG. 3 is a schematic side view for explaining an example of use of the brake pad for a rail brake of the present invention. [Figure 4] Table 1 is a table for explaining the formulation of one example of a friction material in the brake pad for a rail brake of the present invention. [Figure 5] Table 2 is a table for explaining the physical property values of one example of a friction material in the brake pad for a rail brake of the present invention. [Figure 6] Table 3 is a table for explaining the friction coefficient of a friction material in the brake pad for a rail brake of the present invention. [Figure 7] Graph 1 is a graph showing low-speed braking of a braking torque waveform (braking force characteristic) of a friction material in the brake pad for a rail brake of the present invention. [Figure 8] Graph 2 is a graph showing high-speed braking of a braking torque waveform (braking force characteristic) of a friction material in the brake pad for a rail brake of the present invention. MODE FOR CARRYING OUT THE INVENTION

[0020] In this invention, a brake pad 1 for rail brakes is realized that has a friction material 2 attached to the lower surface 10a of the back plate 10 and is based on metal, and the friction material 2 is composed of a metal component, a ceramic material and a lubricating component, so that it exhibits a moderately high braking force in the initial stages of braking, and thereafter the braking force gradually increases steadily until braking is completed, and the friction material has high physical strength. [Examples]

[0021] The brake pad for rail brakes of the present invention will be described using an embodiment shown in Figures 1 to 8.

[0022] As shown in Figure 1, the brake pad 1 for the rail brake in this embodiment has a friction material 2 made of metal attached to the lower surface 10a of the back plate (base metal) 10, and the friction material 2 is composed of a mixture of metal components, ceramic materials and lubricating components. The following describes each component in detail.

[0023] The rail brake pad 1 of this embodiment is used in a container crane 20 as a general rail-running machine, as shown in Figure 2 or Figure 3. The container crane 20 is deployed near a quay 30 in a harbor and has rails 21 laid on the quay 30, support legs 22 of the crane body, a running device 24 equipped with running wheels 23 that are provided below the support legs 22 and can roll along the rails 21, and a rail brake 25.

[0024] If the container crane 20 is buffeted by strong winds during cargo handling operations, it may run off course against the operator's will, potentially colliding with or collapsing adjacent machinery or nearby structures. For this reason, a rail brake 25, as shown in Figure 2 or Figure 3, is provided as an emergency device to prevent runaway. This rail brake 25 is configured to apply braking by pressing a rail brake pad 1 against the running wheel rolling surface 21a of the rail 21 through the operation of a fluid pressure cylinder 26.

[0025] As shown in Figure 3, the rail brake pad 1 is configured to be able to press against and separate from the rolling surface 21a of the running wheel as the rod 26a of the fluid pressure cylinder 26 moves up and down. Specifically, a pressing plate 26b is provided at the lower end of the rod 26a of the fluid pressure cylinder 26, and a back plate 10 is attached to the lower end surface of this pressing plate 26b, thereby enabling the rail brake pad 1 to be attached to the pressing plate 26. The rail brake pad 1 is configured to be able to press against and separate from the rolling surface 21a of the running wheel as the rod 26a of the fluid pressure cylinder 26 moves up and down.

[0026] As shown in Figure 1, the friction material 2 of the brake pad 1 for the rail brake is attached to the lower surface 10a of the back plate 10 and is made of metal as the base material.

[0027] Specifically, the friction material 2 in this embodiment is formed by compounding a metal component, a ceramic material, and a lubricating component, and is formed by pressure molding and sintering a powder compounded with the metal component, ceramic material, and lubricating component. It should be noted that the friction material in this invention is not limited to one compounded with a metal component, a ceramic material, and a lubricating component, but also includes one compounded with a metal component and a ceramic material.

[0028] Suitable metal components include copper or iron powder or copper or iron fibers. Other metals such as nickel and chromium may also be added. In this example, the metal components (metals) shown in Figure 4 are included.

[0029] It is preferable that the metal component be blended at 60-70% by weight. If the metal component is less than 60% by weight, the strength will be insufficient, and the brake material may deform or break under braking load. If it is more than 70% by weight, the metallic properties will be too pronounced, and if copper is the base, malleability and ductility will be increased, which may also cause the brake material to deform or break under braking load. In this embodiment, as shown in Figure 4, the metal component (metal) is blended at 65% by weight. The other metal component (metal) in Figure 4 is chromium (Cr).

[0030] Suitable ceramic materials include SiC, zircon sand, and mullite. In this embodiment, a ceramic material with the composition shown in Figure 4 is used.

[0031] It is preferable that the ceramic material is blended in an amount of 20-25% by weight. If the amount of ceramic material is less than 20% by weight, the grinding performance will be insufficient and the expected friction force will not be obtained, and if it is more than 25% by weight, the grinding performance will be excessive and will attack and damage the mating surface (rail). In this embodiment, as shown in Figure 4, the ceramic material is blended in an amount of 20% by weight. The other ceramic material in Figure 4 is alumina.

[0032] Suitable lubricating components include materials with sliding properties such as carbon (graphite material) and molybdenum sulfide. In this example, a lubricating component (lubricant) with the formulation shown in Figure 4 is used.

[0033] It is preferable that the lubricating component is blended in an amount of 5 to 15% by weight. In this embodiment, as shown in Figure 4, the lubricating component (lubricant) is blended in an amount of 15% by weight. If the amount of lubricating component is less than 5% by weight, the sliding properties will be poor and the frictional resistance of the sliding surface will be large, resulting in unstable braking force. If it is more than 15% by weight, the coefficient of friction will be low and the braking force will decrease. The other lubricating component (lubricant) in Figure 4 is molybdenum sulfide.

[0034] It is preferable that the friction material 2 has a coefficient of friction of 0.25 to 0.45. If the coefficient of friction of the friction material 2 is less than 0.25, the force that applies the brakes and maintains the crane's posture will be reduced, and if an external force greater than the frictional force is applied, the crane will move. If it is greater than 0.45, there is a possibility of damaging the opposing rail. In this embodiment, as shown in Figure 6, the coefficient of friction is configured to be slightly greater than 0.25.

[0035] The friction material 2 is preferably configured with a bending strength of 10 to 100 MPa. If the bending strength of the friction material is less than 10 MPa, the strength of the friction material 2 itself is low, and there is a risk that it will not be able to withstand the hydraulic load during braking, causing damage to the brake material. If it is greater than 100 MPa, the friction material 2 itself will be very strong and hard, and there is a risk that it may damage the opposing rail. In this embodiment, as shown in the physical properties in Figure 5, it is configured with a bending strength of 13.8 MPa, and has material strength that can withstand vertical and shear loads.

[0036] The friction material 2 is preferably configured with a bulk density of 4.0 to 8.0. If the bulk density of the friction material is less than 4.0, sufficient bending strength cannot be obtained, and the necessary material strength of the friction material 2 itself cannot be obtained. If it is greater than 8.0, the friction material 2 will be too strong and very hard, which may cause damage to the opposing rail. In this embodiment, as shown in the material properties in Figure 5, it is configured with a bulk density of 4.34, and is made of a dense material that can withstand a load of 30 tons or more in the vertical direction.

[0037] The rust-preventive layer 3 of the rail brake pad 1 covers the surface of the friction material 2 and is made of ceramic material.

[0038] Suitable ceramic materials for forming the rust-preventive layer 3 include, for example, alumina and / or mullite. Using alumina in the rust-preventive layer results in a ceramic that is stable against the external environment, providing not only excellent braking and holding power, but also a high rust-preventive effect because the metal base prevents the wear material from coming into contact with the external environment. Using mullite in the rust-preventive layer, which has a higher amorphous phase and fewer pores than alumina, further prevents the wear material from coming into contact with the external environment. Furthermore, using both alumina and mullite in the rust-preventive layer can provide an even higher rust-preventive effect.

[0039] In this embodiment, the anti-corrosion layer 3 is composed of alumina and mullite, and is constructed by coating the friction material 2 with mullite and then coating it with alumina. By coating the wear material with mullite, which has a large amorphous phase and few pores, and then coating the mullite with alumina, the pores of the mullite can be filled, and further exposure of the wear material to the external environment can be prevented, thus demonstrating a higher anti-corrosion effect.

[0040] In this embodiment, the rust-preventive layer 3 is coated onto the surface of the friction material 2 by thermal spraying. Since it is coated while sintering, it can be applied more firmly to the substrate.

[0041] Furthermore, the anti-corrosion layer 3 is formed with a higher coefficient of friction (μ0) than the friction material 2. As a result, the anti-corrosion layer 3 is the first to contact the rail during braking, and by configuring the anti-corrosion layer 3 with a high coefficient of friction, a stable frictional force can be exerted from the initial stages of braking.

[0042] The coefficient of friction (μ0) of the rust-preventive layer 3 is preferably 0.45 to 0.60. If it is less than 0.45, it will be the same as or lower than the coefficient of friction of the friction material 2, and therefore will not be able to play an auxiliary role in compensating for the instability of frictional force that tends to occur in the initial stages of braking. If it exceeds 0.60, the coefficient of friction during braking will be too high, resulting in large frictional resistance, which may place an excessive load on components constituting the brake system, such as brake calipers, potentially leading to damage. Furthermore, if a braking load exceeding the strength of the rust-preventive layer 3 is applied, there is a risk that the rust-preventive layer 3 itself may be damaged. In this embodiment, the coefficient of friction (μ0) of the rust-preventive layer 3 is formed to 0.50.

[0043] As described above, the brake pad 1 for rail brakes of the present invention has a metal-based friction material 2 attached to the lower surface 10a of the back plate 10, and the friction material 2 is composed of a metal component, a ceramic material and a lubricating component, so that it is a metal-based brake pad for rail brakes that is suitable for the operating conditions of rail brakes, exhibits a moderately high braking force at the beginning of braking, and thereafter the braking force gradually increases steadily until braking is completed, and the brake pad 1 for rail brakes is composed of a friction material with high physical strength. Specifically, the braking force due to the friction between the metal component of the friction material and the rail exhibits a moderately high braking force at the beginning of braking, and thereafter the braking force gradually increases steadily due to the ceramic material until braking is completed. More specifically, when braking, high heat is instantaneously generated on the sliding surface between the friction material and the rail due to friction, and the wear particles of the friction material melt due to this heat, and an oxide film is formed and spread on the sliding surface. By grinding this oxide film with an abrasive ceramic material, frictional force is generated and acts to increase the braking force. The ceramic material used in this compound is heat-resistant, allowing it to maintain grinding performance even at high temperatures and generate stable friction. Furthermore, the inclusion of lubricating components enhances sliding properties, facilitating the formation of an oxide film on the sliding surface during braking. These combined effects contribute to the aforementioned benefits.

[0044] (Coefficient of friction) One embodiment of the brake pad for rail brakes of the present invention was manufactured by sintering a friction material having the composition shown in Figure 4 at approximately 650 to 800°C. The coefficient of friction of the friction material in the brake pad for the rail brake of this embodiment was repeatedly measured using a friction coefficient measurement tester, and the results shown in Figure 6 were obtained. The average coefficient of friction (μs) was 0.266, and the average friction force was 265.93 Fs [gf].

[0045] (Braking force characteristics: low speed braking) Figure 7 is a graph showing the braking torque waveform (low-speed braking) of the friction material in one embodiment of the brake pad for rail brakes of the present invention. In this graph, the horizontal axis is time (s) and the vertical axis is voltage (V), and it shows the results of repeating braking torque measurements three times (N1, N2, N3). The voltage is the value detected by the load cell of the brake evaluation test machine during control, and it indicates the torque load during braking. From this braking torque waveform, it was confirmed that during low-speed braking, the braking characteristics are such that "a moderately high braking force is exerted at the initial stage of braking, and then the braking force gradually increases while remaining stable until braking is completed."

[0046] (Braking force characteristics: high speed braking) Figure 8 is a graph showing the braking torque waveform (high-speed braking) of the friction material in one embodiment of the brake pad for rail brakes of the present invention. In this graph, the horizontal axis is time (s) and the vertical axis is voltage (V), and it shows the results of repeating braking torque measurements three times (N1, N2, N3). The voltage is the value detected by the load cell of the brake evaluation test machine during control, and it indicates the torque load during braking. From this braking torque waveform, it was confirmed that even during high-speed braking, the braking characteristics were such that "a moderately high braking force is exerted at the beginning of braking, and then the braking force gradually increases while remaining stable until braking is completed."

[0047] The brake pads for rail brakes developed in this invention aim to prevent port cranes from being moved by strong winds and to stop them if they do move. Since various wind conditions are possible and the speed at which port cranes move varies depending on the wind conditions, data was collected for two scenarios: low-speed and high-speed movement (see Figures 7 and 8). The results showed that the brake material exhibited similar braking torque waveforms at both low and high speeds, confirming that it can exert its braking force under any circumstances. [Explanation of symbols]

[0048] 1. Brake pads for rail brakes 2 Friction material 3. Rust-preventive layer 10 Backplate 10a Bottom side 20 Container Cranes 21 rails 21a Rolling surface of running wheels 22 Support legs of the crane body 23 Running wheels 24. Running gear 25 Rail Brake 26 Fluid pressure cylinder 26a Rod 26b Pressing plate 30 Wharf

Claims

1. A brake pad for rail brakes, characterized in that it has a friction material attached to the underside of a back plate and is based on metal, and the friction material is composed of a mixture of metal components and ceramic materials.

2. The brake pad for a rail brake according to claim 1, wherein the friction material is composed of a lubricating component.

3. The brake pad for rail brakes according to claim 2, wherein the metal component is blended in a proportion of 60 to 70% by weight, the ceramic material in a proportion of 20 to 25% by weight, and the lubricating component in a proportion of 5 to 15% by weight.

4. The brake pad for rail brakes according to claim 1 or 2, wherein the metal component is composed of copper, iron, nickel, or chromium, or a composite of two or more of these.

5. The brake pad for rail brakes according to claim 1 or 2, wherein the ceramic material is composed of SiC, zircon sand, or mullite, or a composite of two or more of these.

6. The brake pad for a rail brake according to claim 2, wherein the lubricating component is composed of graphite material and / or molybdenum sulfide.

7. The brake pad for a rail brake according to claim 1 or 2, wherein the friction material has a coefficient of friction of 0.25 to 0.

45.

8. The brake pad for a rail brake according to claim 1 or 2, wherein the friction material has a bending strength of 10 to 100 MPa.

9. The brake pad for a rail brake according to claim 1 or 2, wherein the friction material has a bulk density of 4.0 to 8.

0.

10. The brake pad for a rail brake according to claim 1 or 2, wherein the brake pad for the rail brake has a rust-preventive layer covering the friction material, and the rust-preventive layer is made of a ceramic material.

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