DESC:
TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to a brake shoe part in automobiles and more particularly, the present invention relates to a method for enhanced reliability and cost effective manufacture of web members and brake shoe web thereof.

BACKGROUND

[002] The braking system in automobiles comprises of a rotary drum brakes that are commonly used in motor vehicles that includes but not limited to cars, trucks, large industrial vehicles and the like. The rotary drum brake further comprises two cooperating parts such as a rotary drum which is typically affixed to the vehicle wheel and a pair of brake webs mounted on a support plate to form a brake shoe assembly and carried by the vehicle's suspension.

[003] Brake webs are typically formed in generally symmetrical pairs, with each webs members having a semi-cylindrical outer surface covered with a friction material. The friction material is typically mounted on a brake shoe table formed into a semi-cylindrical shape generally corresponding to the contour of the associated brake drum. Typically, the web member are stamped steel plate, radially inboard and securely affixed to the brake shoe table. The brake webs members are typically obtained using blanking, stamping, welding, forging, hydraulic presses. Conventionally, the manufacturing process of the brake shoes assembly involves the attachment of web members and table members by means of a high energy joining process or stamping process.

[004] However, modern vehicles require precisely made brake shoe assemblies. As illustrated in figure 1, the brake web members are conventionally made with a multiple step that is relatively complex and expensive process. It involves the sheet shearing which is thereby followed by web blanking process. After the webs members are joined to the table, appropriate slots or holes are pierced in the webs to make the brake shoe assembly workable with the remainder of a brake assembly. The brake web members also undergoes a coining process such as to achieve the required shape. The slots in the webs must be heat treated to achieve a high hardness. Heat treating the webs is more difficult after they have been joined to the table.

[005] Reference is also made to US 5137203 A, wherein a drum brake shoe is provided by fine blanking the brake web so that the web has radially extending weld projections at a circumferential edge, with a radial recess disposed on each side of a weld projection. As a brake shoe rim is fed through a welding and forming mechanism, a flat surface of the rim engages a radially extending weld projection and a weld is affected. Welding wheels of the mechanism rotate to bend the rim and engage the rim with the next weld projection as a weld is effected between the rim and web. The manufacturing method will provide a more consistent welding process that will result in a higher percentage of quality welds and less scrappage.

[006] However, due to the use of blanking process only less contact of web member thickness on to the brake shoe table is achieved during welding. Through the blanking process, only 80% of the web thickness contact on to the table during the welding process is achieved. Further, poor weld joints is achieved during weld penetration and contact are between brake shoe table and web member. Furthermore, weaker grain flow along with stress direction is observed. Furthermore, in blanking process the skeleton part get scrapped from the obtained brake web, which leads to input versus output finished material yield being only 65 %.
[007] Thus, due to the hitherto drawbacks of the conventional manufacturing methods of the brake web members, there is a dire need to provide an improved method that eliminates the drawbacks of the blanking process, stamping, welding, forging, hydraulic presses and the like.

SUMMARY OF THE INVENTION

[008] The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

[009] It is the primary object of this invention to minimize or eliminate the drawbacks of the conventional processes that includes blanking, stamping, welding, forging, hydraulic presses and the like, to manufacture the brake web members.

[0010] Another object of this invention is to provide an improved brake shoe assembly wherein the web member is manufactured using a hot forming process.

[0011] Yet another object of the present invention is to provide a brake web that is capable of achieving 100% contact of web thickness on the table.

[0012] Still another object of the present invention is to provide a hot forming process for the manufacture of the brake web such that the finished material yield is substantially improved.

[0013] Accordingly, in one aspect of the present invention, there is provided a method for manufacturing at least one brake shoe web by hot forming technique, comprising:
• heating, by means of an induction equipment, a flat strip or sheet so as to soften the piece of metal;
• pressing, by means of a press, said sheet to form a die set;
• coining or piercing, by punch and die, said die set to obtain a desired shape of brake web members.

[0014] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0015] Figure 1 illustrates a flow chart of the conventional process of manufacturing brake web members according to the prior art.

[0016] Figure 2(a) illustrates a schematic of a rotary drum brake comprising the brake shoe assembly and Figure 2(b) illustrates the exploded view of the rotary drum brake, in accordance with one implementation of the present invention.

[0017] Figure 3(a) illustrates a working flow of the hot forming process to manufacture brake web members, in accordance with one implementation of the present invention. Figure 3(b) illustrates the schematic of the hot forming process used for the manufacture of the brake shoe web, in accordance with one implementation of the present invention.

[0018] Figure 4 illustrates the schematic of the brake web manufactured by the hot forming process, in accordance with one implementation of the present invention.

[0019] Figure 5(a) illustrates a contact between a brake web members and brake shoe table according to prior art, and figure 5(b) illustrates a contact between a brake web members and brake shoe table according to the present invention.

[0020] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0021] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0022] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0023] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0024] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0025] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0026] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0027] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0028] The present invention provides an improved manufacturing process for utilization in brake shoe assembly. In one implementation, the manufacturing process involves the use of hot forming process in place of conventional web blanking process in making of brake web members. The hot forming process works through heating the brake web members and forming to achieve required shape and thereby to achieve complete contact between the brake web member and the table. Particularly, the present invention relates to the design, manufacture and supply of brake web members forming Die sets with Pick and Place Robotic automation.

[0029] In one implementation, the present invention discloses a manufacturing method for the production of Brake Web members using a Hot Forming Process. The web members is thereby utilized in the manufacture of a brake shoe assembly which may be used in a brake assembly of a vehicle.

[0030] In one implementation, the figure 4 illustrates the web member manufactured using a hot forming.

[0031] In one implementation, the figure 2(a) illustrates a rotary drum brake comprising the brake shoe assembly and 2(b) illustrates the exploded view of the rotary drum brake and show the brake shoe table (1) and the brake web member (2).

[0032] In one implementation, the figure 3(a), illustrates a working flow of the hot forming process for the manufacture of the brake web members and figure 3(b) illustrates a schematic of the hot forming process. As shown in figures 3(a) and 3(b), the manufacturing process to obtain the brake web members commences by obtaining a flat strip or sheet (step 1), followed by inducting heating the flat strip (step 2) and hot forming using punch and die (step 3) to securely affix the brake web member to the brake shoe table such as to obtain a brake shoe assembly. Due to the occurrence of the thickness variation during manufacturing the brake web through Hot Forming process, a Coining Operation (step 4) may be introduced to avoid this variation.

[0033] In one implementation, the manufacturing process further comprises cooling, by means of a cooling system, the brake web members to bring down the temperature of said brake web members to the range of 50°C to ambient room temperature (step 5) and scaling, by thumb blast, to remove the unwanted portion from said brake web members (step 6).

[0034] In one implementation, the manufacturing process of the present invention requires an Induction Heating equipment and die and punch equipment to form the brake web members.

[0035] In one implementation, by the use of Hot Forming process, 100 % of the Web thickness contact on to the brake shoe table during welding can be achieved. Further, the Weld penetration and the contact area between the brake shoe table and the web member is also good. Hence, the quality of the Brake web members and some extent life of the Brake shoe assembly is improved.

[0036] In one implementation, the hot forming process of the present invention involves critical optimum parameters which may be utilized in the manufacture of the said brake web members. The critical parameter are listed as follows:

S.I. No. Process Description Specification M/C
Capacity
1 Induction Heating 850 -900 degree C 1500 degree C
2 Pressing Ton during Hot Forming 8 to 15Ton 300T
3 Coining /piercing 100 to 150 Ton 300T
4 Forced Air Cooling ( Temp drop from 650 degree to 50 C) 50 degree C to ambient room temperature -NA-
5 Thumb Blast Remove the scaling -NA-

[0037] According to the existing Process such as the Blanking process wherein the Punch forcefully shear the part of the sheet.so that break off part can be identified at the corner. However the end part of web after blanking as shown in figure 5 (a), the contact between the break shoe table (1) and the brake web member (2) during welding process (as it chamfer on one end ) is just 80%. However, in the Hot Forming Process of the present invention, as shown in figure 5(b): the flat strip or sheet may be heated up and forming to web structure with one end web radius (inner) contact with Punch and Other end of web (Outer) contact with Die so that there cannot be any chance of break off in the web member (2), thus achieving 100 % contact between the to the break shoe table (1) and the brake web member (2).

[0038] In one exemplary implementation, for induction heating, induction Plate/Strip Heater can be used with specification that may be selected from, but not limited to, 250 KW, 20 KHz Converter, 3 Phase, 415V AC, with all necessary power components. These specification can be varied according to requirement and is not fixed to these values. The induction heating plate/strip heater is provided with Insulated gate bipolar transistor (IGBT) Converter Power source, Water cooling system and Material infeed shuttling system.

[0039] In one exemplary implementation, main specification of the induction plate/strip heater used in the present invention are as follows:
• Converter system: 250 KW, 15-20 KHz, 415V, 3 Phase with necessary Power components, IGBT Power source.
• PLC Controls and panel: Mitsubishi PLC with Delta / Fatek HMI in Rittal Panel with Schneider Switch Gears. Cables / wires, Electrical hoses and Glands are of LAPP make.
• Input Components feeding system and holding capacity of 2 x 150 Nos of Shuttling type with Pusher system.
• Heating Inductor coil chamber suitable for 850 – 900 deg C operation with min 8 Secs per component output with easy maintenance and coil change system.
• Output Hot Components feeding and holding system to enable the Robot to pick and place at the Press.
• 3 Way Accept / Reject system for hot components with Pyrometer and pneumatic pushing system.
• Cooling water System of D. M. Water re-circulating system consists of
a) Non-Ferrous Pump. b) stainless steel (S.S.) Plate Type Heat Exchanger. c) De-Ioniser. D) S. S. Filter. e) Pressure Gauges. f) Carbon free hoses / S. S. Piping and Valves for interconnection. 210 LPM and 4Kgs/Sqcm pressure. g) Temperature monitoring, Pressure monitoring and flow monitoring sensors / switches.

[0040] In one exemplary implementation, for pressing, 300 Ton Press, C-Frame type, Model: SN2-300 can be used, as shown in Step 3 of figure 3(b).

[0041] In one implementation, in the steps of supplying the brake shoe web during the hot forming process:
• Die Set (1) – Press tool for Forming (as shown in step 3 of figure 3(b))
• Die Set (2) – Press tool for Piercing, Punching and Trimming (as shown in step 4 of figure 3(b)
• Input conveyor/ locator for Hot component (from induction heater) to pick by any automatic mechanism (Robot) and place on Forming Die-1
• Component lifting, singling mechanism and chute, pushing arrangement from Die-2 to a cooling system (Air cooling chamber) automatically.

[0042] Further, in one implementation, the outer and inner profile radius of the concentric semi-circle shape of the blank web obtained by the hot forming technique, as shown in figure 4, can be at common center point. However, in another implementation, it can be identified that the center point of semi-circle shape of the blank web having variation and not in concentric.

[0043] In one preferable implementation, the outer and inner profile radius of the blank web are in concentric semi-circle. This shape can be achieved from flat straight strip and formed to the said concentric semi-circle through Hot forming process.

[0044] Some of the important benefits of the present invention are mentioned below:
• The hot forming process of the present invention will result in 100% of web thickness contact on to the break shoe table during welding and eliminate a web break out. This will improve the weldability.
• The present invention improves weld penetration and contact area between table and web and thereby improving life of the brake shoe.
• The present invention results in an improvement in flat strip material yield from 65 % to 95%. With Flat strip heating and forming through Hot forming technique, the flat strip or sheet can formed to the desired shape of the brake web with zero wastage in the material such that the finished material yield is increase to 95 %.
• The manufacturing process of the present invention is cost effective.
• The manufacturing process of the present invention enables reduction in Input material.
• The present invention results in an improvement in machining operation.
• Improvement in the Strength and improvement in Quality.
• The present invention results in material optimization
• The present invention results in a stronger grain flow perpendicular to the stress.
• With Hot forming process, stress get relieved and improved machinability and tool life is achieved.

[0045] Although a method of manufacturing web brake shoe have been described in language specific to structural features, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples of implementations of the method of manufacturing web brake shoe.
,CLAIMS:
1. A method for manufacturing at least one brake shoe web by hot forming technique, comprising:
heating, by means of an induction equipment, a flat strip or sheet so as to soften the piece of metal;
pressing, by means of a press, said sheet to form a die set;
coining or piercing, by punch and die, said die set to obtain a desired shape of at least one brake web member.

2. The method as claimed in claim 1, further comprises :
cooling, by means of a cooling system, said brake web members to bring down the temperature of said brake web members to the range of 50°C to ambient room temperature;
scaling, by thumb blast, to remove the unwanted portion from said brake web members.

3. The method as claimed in claims 1-2, further comprises: welding, said brake web members with a brake shoe table to obtain said brake shoe web with complete contact between said brake web members and said brake shoe table.

4. The method as claimed in claim 1, wherein induction equipment for induction heating of said flat strip or sheet is selected from an induction plate and/or a strip heater.

5. The method as claimed in claim 4, wherein said induction heating of said flat strip or sheet is done at a temperature selected in the range of 850-950°C.

6. The method as claimed in claim 1, wherein said pressing is done at a pressure selected in the range of 8 to 15Ton.

7. The method as claimed in claim 1, wherein coining or piercing is done at a pressure selected in the range of 100 to 150 Ton.

8. The method as claimed in claims 1-7, wherein said shape of said brake web obtained by said hot forming technique comprises variable or concentric radius point.