Method for manufacture of brake pad with modified backing plate

Abstract

To provide a method for manufacturing brake pads which avoids or sufficiently reduces the disadvantages occurring in the prior art, such as complexity, time consumption, cost, and the need for additional cleaning steps, while simultaneously ensuring a firm and durable connection between a friction lining and a backing plate.SOLUTION: The present invention relates to a method for manufacturing a brake pad having a backing plate and a friction lining, the method comprising at least the following steps: a) providing a backing plate for fixing a friction lining, with or without an intermediate layer between the backing plate and the friction lining, on the backing plate; b) roughening at least a partial region of the surface of the backing plate; and c) fixing the friction lining onto the roughened surface of the backing plate, wherein the roughening of the surface of the backing plate is performed using a pulsed high-pressure water jet.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] (Description of Related Application) This application is based on the priority claim of German Patent Application No. 10 2024 101 835.6 filed on January 23, 2024, and the entire content of the application is incorporated herein by reference.

[0002] The present invention relates to a method for manufacturing brake pads, particularly disc brake pads, which is characterized in particular by the pretreatment or improvement of a backing plate (back plate: lining support plate).

Background Art

[0003] Automotive brake pads often consist of a backing plate and a friction lining (friction material) located on and fixed to the backing plate. An additional intermediate layer can be further arranged between the friction lining and the backing plate, and this intermediate layer often functions as a noise attenuation layer. In this case, this intermediate layer is connected to the friction lining and the backing plate. The friction lining or the intermediate layer or the attenuation layer is usually fixed on the backing plate using an adhesive. If the friction lining is made of a sintered material or contains a sufficient amount of a sintered material, the friction lining can be fixed to the backing plate by hot pressing without using an adhesive. In addition, the friction lining can also be fixed to the plate surface using fixing means such as bolts, pins, and rivets.

[0004] In order to improve the bonding of the friction lining or the intermediate layer to the backing plate, in the prior art, a predetermined processing or generally a predetermined preparation treatment is performed on the surface of the plate. For this purpose, the support plate is machined, for example, mechanically, whereby small hooks are created on the plate surface (crimping). If the plate consists of a casting material such as gray cast iron, for example, the holding elements can be attached directly to the plate surface or the edge of the plate surface during casting. The surface of the backing plate can also be prepared by structuring using a laser beam or by sandblasting for better bonding to the friction lining.

[0005] Now, the following Patent Document 1 (DE 197 12 203 A1) shows a method for manufacturing a brake pad. For the case where the backing plate consists of a support metal plate made of rolled or unrolled steel, for example, a surface treatment for better adhesion of the friction lining by a chemical pickling process, sandblasting or water blasting, or other surface removal or deformation processes is described as advantageous. At this time, pickling in a phosphate treatment apparatus is preferred.

[0006] The following Patent Document 2 (DE 32 32 865 A1) also discloses a manufacturing method for a brake pad. The iron pressure plate is cleaned using the water jet method, and at this time, a surface roughness with an average roughness value (arithmetic mean roughness) Ra of from 0.8 μm to 1.3 μm is generated. However, in order to ensure a reliable connection with the friction lining, a subsequent surface coating is necessary. Using a dry rough blowing method (for example, the sandblasting method), a surface roughness with an average roughness value Ra of from 7.7 μm to 8.7 μm is achieved.

[0007] The following Patent Document 3 (US 6,269,669 B1) discloses a wet blasting method using particles for a backing plate. According to the following Patent Document 3, for better bonding with the friction material, the backing plate is conventionally roughened to a surface roughness having an average roughness value Ra between 2 μm and 7 μm.

[0008] The following Patent Document 4 (EP 1,178,236 A2) discloses a wet blasting method using particles for a backing plate, where a preferred surface roughness having an average roughness value Ra from 1.5 μm to 7 μm is provided for the primer, and a friction material is provided on the primer. The preferred roughness depth (maximum height roughness) Rz takes a value from 10 μm to 30 μm.

[0009] The following Patent Document 5 (JP 5328609 B2) discloses a blasting method using steel balls for a backing plate. The blasted backing plate has a surface roughness having a roughness depth Rz of 5 μm to 15 μm or 20 μm. After the blasting treatment, an adhesive for the friction material is further applied onto the backing plate.

[0010] The following Patent Document 6 (DE 10 2019 213 464 A1) discloses a method for manufacturing a friction brake body, where the backing plate is made of gray cast iron incorporating graphite. Before the application of the friction lining coating, the graphite near the surface is reduced or removed by water jet treatment. The application of the friction lining coating is performed by laser deposition welding (laser cladding).

[0011] In addition, in the prior art, the use of the water jet method for surface treatment is known. For example, Ecoclean-Group / DE provides a method and apparatus for pretreating a metal surface before a thermal spraying method for applying hard metal or hard alloy.

Prior Art Documents

Patent Documents

[0012] [Patent Document 1] German Patent Application Publication No. 19712203 [Patent Document 2] German Patent Application Publication No. 3232865 [Patent Document 3] U.S. Patent No. 6269669 [Patent Document 4] European Patent Application Publication No. 1178236 [Patent Document 5] Japanese Patent No. 5328609 [Patent Document 6] German Patent Application Publication No. 102019213464 [Patent Document 7] U.S. Patent Application Publication No. 2017 / 0204920 [Non-Patent Document]

[0013] [Non-Patent Document 1] Master's thesis by N. O’Neil, "Optimized Surface Roughening by Pulsed Waterjet for Suitable Adhesion Strength of Plasma Transferred Wire Arc Coating" (Optimized roughening treatment by pulsed waterjet for appropriate adhesion strength of plasma transferred wire arc coating), Carleton University, Ottawa, Ontario, 2020; see pages 49, 53, 63, 64 there (https: / / repository.library.carleton.ca / downloads / z890rv29c) [Summary of the Invention] [Problems to be Solved by the Invention]

[0014] The above-mentioned measures for improving the bonding of the intermediate layer or the friction lining on the surface of the backing plate during the manufacture of brake pads are complex, time-consuming and costly, leaving room for improvement. In addition, these measures carry the risk that substances added in the pretreatment (such as sand particles) or particles generated in the processing (such as chips, metal particles) must be removed by additional cleaning steps.

[0015] Therefore, the problem underlying the present invention is to provide a method for manufacturing a brake pad that avoids or sufficiently reduces the drawbacks occurring in the prior art and at the same time guarantees a fixed and permanent connection between the friction lining and the backing plate.

[0016] In addition, it should be confirmed whether additional advantages such as improved safety during high-power use in, for example, racing sports and improved comfort such as a reduction in brake noise occurring during continuous operation can be achieved by the improved connection between the friction lining and the backing plate.

Means for Solving the Problem

[0017] Based thereon, according to the present invention, in the manufacturing process of a brake pad, the backing plate (lining support plate) is pretreated by roughening the surface (entirely or partially) for receiving an adhesive and an intermediate layer, or for receiving an adhesive and a friction lining, or preferably for receiving an intermediate layer and / or a friction lining without prior adhesive application.

[0018] That is, according to a first aspect of the present invention, A method for manufacturing a brake pad having a backing plate and a friction lining, The method comprises at least the following method steps, namely, a) providing a backing plate on the backing plate, with or without an intermediate layer between the backing plate and the friction lining, for fixing the friction lining; b) roughening at least one partial area of the surface of the backing plate; and c) fixing the friction lining on the roughened surface of the backing plate, which is a method comprising: wherein the roughening of the surface of the backing plate is performed using a pulsed high-pressure water jet; A method is proposed, which is characterized by this. Furthermore, according to a second aspect of the present invention, it is proposed to use a backing plate roughened by the method described in the first aspect for manufacturing a brake pad. Furthermore, according to a third aspect of the present invention, A method for reducing brake noise caused by a brake pad, is proposed, which is characterized in that the brake pad manufactured by the method described in the first aspect is used in a vehicle. Furthermore, according to a fourth aspect of the present invention, it is proposed to use a brake pad manufactured by the method described in the first aspect to reduce brake noise caused by the brake pad. Furthermore, according to a fifth aspect of the present invention, a brake pad manufactured by the method described in the first aspect is proposed. It should be noted that the reference signs in the drawings appended to the claims of this application are solely for facilitating the understanding of the present invention and are not intended to limit the illustrated form.

Advantages of the Invention

[0019] Due to the roughening according to the present invention, good adhesion between the backing plate and the friction material or the intermediate layer is achieved, advantageously without using an adhesive.

Embodiments for Carrying Out the Invention

[0020] In the present invention, the following embodiments are possible. (Embodiment 1) A method for manufacturing a brake pad having a backing plate and a friction lining, said method comprising at least the following method steps, namely, a) providing a backing plate for fixing the friction lining on the backing plate, with or without an intermediate layer between the backing plate and the friction lining; b) roughening at least one partial region of the surface of the backing plate; and c) fixing the friction lining on the roughened backing plate surface, wherein the roughening of the backing plate surface is carried out using a pulsed high-pressure water jet. (Embodiment 2) Preferably, the partial region is roughened to a surface roughness having a roughness depth from 50 micrometers to 500 micrometers. (Embodiment 3) Preferably, the partial region is roughened to a surface roughness having a roughness depth from 100 micrometers to 350 micrometers. (Embodiment 4) Preferably, the backing plate surface is not treated with an adhesive after roughening and before attachment of the friction lining or the intermediate layer. (Embodiment 5) Preferably, the water jet has a water pressure from 600 bar to 850 bar, and when the backing plate is made of an aluminum-based metal alloy, it has a water pressure from 200 bar to 400 bar. (Embodiment 6) Preferably, the water jet has a pulsation range from 10000 pulses / s to 20000 pulses / s. (Embodiment 7) The water jet preferably has a velocity ranging from 150 m / s to 380 m / s. (Form 8) The water jet preferably strips and scans (roughens) the surface of the backing plate to be roughened at a velocity ranging from 1 mm / s to 10 mm / s, preferably from 1 mm / s to 4 mm / s, particularly from 2 mm / s to 3 mm / s. (Form 9) The ejection nozzle of the water jet is preferably moved (roughened and scanned) at an interval ranging from 15 mm to 50 mm from the surface of the backing plate to be roughened. (Form 10) The water jet preferably hits the surface of the backing plate to be roughened at a right angle. (Form 11) The water jet preferably hits the surface of the backing plate to be roughened at an inclination angle. (Form 12) Preferably, a corrosion inhibitor is added to the water jet. (Form 13) The backing plate is preferably made of a metal alloy based on Fe, Ti, or aluminum, a metal alloy having carbon fibers, or a glass fiber reinforced plastic or a carbon fiber reinforced plastic. (Form 14) To manufacture a brake pad, a backing plate roughened by the method according to any one of Forms 1 to 13 is used. (Form 15) A method for reducing brake noise caused by a brake pad, wherein a brake pad manufactured by the method according to any one of Forms 1 to 13 is used in a vehicle. (Form 16) To reduce brake noise caused by a brake pad, a brake pad manufactured by the method according to any one of Forms 1 to 13 is used. (Form 17) A brake pad manufactured by the method according to any one of Forms 1 to 13. Note that this form of method limitation (or claim) is due to the fact that it is difficult to express accurately the shape of the roughening of the backing plate surface, other than expressing it as "performed using a pulsed high-pressure water jet" (Form 1). As another form of expression, "the roughened shape of the backing plate surface is formed by a pulsed high-pressure water jet" can also be expressed.

[0021] This preparatory treatment of the backing plate is carried out according to the present invention by roughening the plate surface on which the intermediate layer or the friction lining is to be applied. In addition, an adhesive layer can first be applied to the roughened surface. Preferably, the intermediate layer or the friction lining is directly hot-pressed onto the roughened surface. The parameters such as pressure and temperature used for this are corresponding to the values from the prior art and are known to those skilled in the art.

[0022] At this time, the roughening is brought about using a (high-pressure) water jet (water injection). Corresponding devices for such water jet treatment are commercially available and are provided, for example, by Ecoclean-Group / DE.

[0023] Next, the preferred embodiments and parameters for the method according to the present invention will be described in detail.

[0024] Preferably, the so-called pulsating medium-pressure water jet technology, as sold by Ecoclean, is used. In this case, the water jet nozzle is preferably in the form of a so-called pulsed water jet nozzle and is combined with a so-called ultrasonic transducer and operated at a certain operating pressure. The operating pressure preferably takes values up to 850 bar, and the pulsation range generated by the ultrasonic transducer preferably takes values up to approximately 20,000 pulses / s (20 kHz). The water flow rate is preferably clearly above 50 m / s and in particular takes values up to 380 m / s. The water temperature usually corresponds to the pipe temperature (the temperature when water is provided by the supplier within the network), or is within the temperature range of the pipe temperature and the ambient temperature, or room temperature. Usually, it is not necessary to heat the water above room temperature.

[0025] For sufficient roughening of the backing plate surface according to the present invention, it has been found that the use of a pulsed water jet (pulsed water injection) is usually necessary. This is especially true for metal surfaces. A pulsed water jet with a water pressure between preferably 600 bar and 850 bar is used. The pulsation preferably takes values from 10 kHz to 25 kHz, particularly preferably from 10 kHz to 20 kHz.

[0026] Surprisingly, it has been found that in the brake pads having a backing plate processed according to the present invention, the noise generation during the braking process is significantly less compared to such brake pads that are identical in all other respects but have an untreated same support plate. The reason is that the support plate processed according to the present invention has increased damping. In the inspections carried out so far, the damping has been increased in the range from 6.4% to 23% compared to conventional brake pads, depending on the type of lining support and the type of friction material, and it is also possible to take values greater than 30%. At this time, the increased damping and the accompanying obvious noise reduction are due to the significantly increased surface roughness (surface roughness) that can be manufactured according to the present invention, and this surface roughness is located far above the surface roughness conventionally used in backing plates so far.

[0027] That is, the present invention relates to a method for reducing the noise caused by brake pads during the braking process in operation, as well as the use of brake pads according to the present invention for the above-mentioned purpose, and the use of a backing plate according to the present invention for manufacturing brake pads for that purpose.

[0028] According to the present invention, a surface roughness having a roughness depth Rz (maximum height roughness) from 50 micrometers to 500 micrometers is preferred, a surface roughness from 100 micrometers to 350 micrometers is more preferred, and a surface roughness from 150 micrometers to 300 micrometers is particularly preferred. The roughness is preferably measured based on a microscopic image (cut surface image) of the surface processed according to the present invention using a microscope. Such a microscopic image is shown in Figure 3.

[0029] In order to measure the roughness depth Rz, various other methods and, in particular, measuring instruments of various providers have been described in the prior art, and these are known to those skilled in the art (for example, refer to the keyword "roughness measurement" in Wikipedia).

[0030] In the case of an increased surface roughness having a roughness depth Rz of at least 100 μm, depending on the type of lining support and the type of friction material, in the braking process using a brake pad having a backing plate treated according to the invention, a clearly reduced noise generation is already obtained. Particularly good damping and noise reduction will occur, for example, with a surface roughness having a roughness depth Rz from 200 μm to 300 μm.

[0031] General information as well as exemplary information regarding the treatment of metal surfaces and the interaction of those materials (e.g., the material of aluminum alloy A380 and the material of gray cast iron (GCI)) with process parameters can be found, for example, in Non-Patent Document 1 mentioned above. Information regarding suitable measuring methods and measuring instruments for various process parameters can also be found there.

[0032] The speed at which the water jet is guided across the surface of the backing plate to be treated usually takes values between 1 mm / s and 10 mm / s, preferably from 1 mm / s to 4 mm / s, particularly from 2 mm / s to 3 mm / s. These values preferably relate to a backing plate made of steel. Softer materials, such as aluminum or aluminum alloys, can be roughened according to the invention even at higher speeds.

[0033] At this time, the water jet nozzle is preferably in a direction perpendicular to the surface to be processed. However, the processing can also be carried out at different angles. This is advantageous for the processing of a backing plate having a partially recessed surface for the arrangement of the friction lining. By processing at an oblique angle, the edges of the backing plate facing inwards can also be well roughened. The distance between the surface and the nozzle is preferably in the range from 10 mm to 70 mm, particularly in the range from 15 mm to 50 mm.

[0034] In order for the friction material to penetrate well into the surface or in order for the friction material to be connected to the surface as fixedly as possible, usually the entire surface of the backing plate is treated according to the invention.

[0035] In accordance with the present invention, it may be advantageous to add a substance that can prevent corrosion on the surface of the lining support in the short term to the water used. These substances are preferably triethanolamine at a concentration of less than 3%. As a commercially available product, for example, the product Castrol Techniclean HP can be mentioned here, and this product can be added to water at a concentration preferably from 1.5% to 3% by weight.

[0036] By creating a microscopic image (cross-sectional image) of the treated surface, the penetration of the friction material into the roughened surface can be shown and managed. These images show the undercut and anchoring (fixed state) of the friction material on the treated surface with good resolution.

[0037] A preferred backing plate for the purposes of the present invention consists of steel, preferably mild steel, a metal alloy based on Fe and / or Ti, a metal alloy with carbon fibers, or glass fiber reinforced plastic or carbon fiber reinforced plastic (GFRP and / or CFRP). Corresponding lightweight structural support plates are known in the prior art and are described, for example, in the above-mentioned patent document 7 (US 2017 / 0204920 A1).

[0038] Therefore, the advantages of the method according to the present invention for manufacturing brake pads using a brake backing plate having a surface roughened by the water jet method are as follows: - The proposed water jet method requires less time and cost than the corresponding methods known in the prior art for processing the backing plate. - No unwanted residues, such as those occurring in the case of other particle blasting methods such as the sandblasting method, remain on the plate surface later. - The roughened surface is clean at the same time (already cleaned), so that no additional cleaning step is required. - In the water jet method, there is no need to use additional substances such as surfactants or detergents that would increase the method cost. - The method according to the present invention is also particularly suitable for low-cost backing plates made of casting materials such as gray cast iron.

[0039] Hereinafter, embodiments of the present invention will be described. It should be noted that the following embodiments are for facilitating the understanding of the present invention, and are not intended to exclude additions, substitutions, selections, or selective combinations of each disclosed element that can be implemented by those skilled in the art without departing from the technical idea of the present invention.

Brief Description of the Drawings

[0040]

Figure 1

Figure 2

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Figure 7

Example

[0041] Except for the roughening of the backing plate surface according to the present invention, the manufacture of the brake pad is carried out by a method for applying a friction material or a friction lining (with or without an intermediate layer between the friction lining and the backing plate) on the backing plate, which is known in the prior art for various brake pads. This is usually done by pressing (hot pressing) the backing plate and the friction material / friction lining at increased pressure and increased temperature.

[0042] For further improvement of the stability of the brake pad according to the present invention, an adhesive can be applied on the backing plate surface before fixing the friction lining.

[0043] The lining support surface shown in Figure 1b was peeled off (roughened (abgefahren)) using a water jet at a speed of 3 mm / s. This processing was carried out at room temperature. At this time, the water jet had a pressure of approximately 760 bar.

[0044] The backing plate surface shown in Fig. 3 has a roughness depth (Rautiefen) reaching up to approximately 500 μm. The surface was stripped using a water jet with a speed of 1 mm / s. The water jet had a pressure of approximately 760 bar. The shown backing plate surface is made of steel.

[0045] In the backing plate 10 of the brake pad shown in parts in Fig. 4, the area to be roughened was processed using a water jet according to the parameters described with respect to Fig. 1. The backing plate 10 is made of steel. The roughened surface of the backing plate 10 mainly has a roughness depth between 150 μm and 300 μm. The friction material 12 is directly pressed onto the roughened surface of the backing plate 10. The roughened surface of the backing plate 10 provides an engagement (Zahnung) 14 with the friction material 12, improving the bonding and resulting in a distinct reduction in noise.

[0046] It should be noted that the disclosures of the above patent documents and non-patent documents are incorporated herein by their citation. Also, within the framework of the entire disclosure of the present invention (including the claims), further modifications and adjustments of the embodiments are possible based on its basic technical idea. Furthermore, within the framework of the entire disclosure of the present invention, various combinations or selections (including non-selections) of various disclosure elements (including each element of each claim, each element of each embodiment, each element of each drawing, etc.) are possible. That is, the present invention naturally includes all modifications and corrections that a person skilled in the art could make according to the entire disclosure including the claims and the technical idea. In particular, for the numerical ranges described in this document, any numerical value or small range included within the range should be construed as specifically described even if there is no separate description.

Explanation of Reference Numerals

[0047] 1 Pulse water jet nozzle 2 Ultrasonic transducer 3 High-pressure chamber 4 Pulse high-pressure water jet 5 Nozzle chamber 6 Vibration Core 7 High-Pressure Water Inlet 10 Backing Plate (Lining Support Plate) 12 Friction Lining 14 Engagement Part between Backing Plate and Friction Lining

Claims

1. A method for manufacturing a brake pad having a backing plate (10) and a friction lining (12), said method comprising at least the following method steps, namely, a) providing a backing plate (10) on the backing plate (10), with or without an intermediate layer between the backing plate (10) and the friction lining (12), for fixing the friction lining (12); b) roughening at least one partial region of the surface of the backing plate (10); and c) fixing the friction lining (12) on the roughened backing plate surface, wherein the roughening of the backing plate surface is carried out using a pulsed high-pressure water jet (4), characterized in that.

2. The partial region is roughened to a surface roughness having a roughness depth from 50 micrometers to 500 micrometers, characterized in that the method according to claim 1.

3. The partial region is roughened to a surface roughness having a roughness depth from 100 micrometers to 350 micrometers, characterized in that the method according to claim 1 or 2.

4. The backing plate surface is not treated with an adhesive after roughening and before attachment of the friction lining (12) or the intermediate layer, characterized in that the method according to any one of claims 1 to 3.

5. The water jet has a water pressure from 600 bar to 850 bar and, when the backing plate (10) is made of an aluminum-based metal alloy, has a water pressure from 200 bar to 400 bar, characterized in that the method according to any one of claims 1 to 4.

6. The water jet has a pulsation range from 10,000 pulses / s to 20,000 pulses / s, characterized in that the method according to any one of claims 1 to 5.

7. The water jet has a speed from 150 m / s to 380 m / s, characterized in that the method according to any one of claims 1 to 6.

8. The water jet strips and scans the backing plate surface to be roughened at a speed from 1 mm / s to 10 mm / s, preferably from 1 mm / s to 4 mm / s, in particular from 2 mm / s to 3 mm / s, ​ The method according to any one of claims 1 to 7, characterized in that...

9. The ejection nozzle of the water jet is moved at an interval of 15 mm to 50 mm from the surface of the backing plate to be roughened. The method according to any one of claims 1 to 8, characterized in that...

10. The water jet hits the surface of the backing plate to be roughened at a right angle. The method according to any one of claims 1 to 9, characterized in that...

11. The water jet hits the surface of the backing plate to be roughened at an inclination angle. The method according to any one of claims 1 to 9, characterized in that...

12. An anti-corrosion substance is added to the water jet. The method according to any one of claims 1 to 11, characterized in that...

13. The backing plate (10) is made of a metal alloy based on Fe, Ti, or aluminum, a metal alloy having carbon fibers, or a glass fiber-reinforced plastic or a carbon fiber-reinforced plastic. The method according to any one of claims 1 to 12, characterized in that...

14. Using the backing plate (10) roughened by the method according to any one of claims 1 to 13 for manufacturing a brake pad.

15. A method for reducing brake noise caused by a brake pad, characterized in that the brake pad manufactured by the method according to any one of claims 1 to 13 is used in a vehicle. A method characterized by...

16. Using the brake pad manufactured by the method according to any one of claims 1 to 13 to reduce brake noise caused by the brake pad.

17. A brake pad manufactured by the method according to any one of claims 1 to 13.

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