TITLE

NOVEL MANUFACTURING METHOD OF A SINGLE PIECE BRAKE SHOE USING A SINGLE METAL SHEET

FIELD OF THE INVENTION

This invention generally relates to a method for the manufacture of the brake mechanism for an automotive vehicle and particularly relates to a method for the manufacture of brake shoes. More particularly this invention relates to a novel, cost-effective manufacturing method of brake shoes as a single unit using a single metal sheet.

BACKGROUND OF THE INVENTION

Drum Brake assembly is used in the wheels of any automobile. Drum Brake assembly consists of major parts like Back plate, Wheel cylinder assembly, Two numbers of Brake shoes assembly and few other parts to make a complete Drum Brake assembly.

Typical Brake Shoe assembly consists of three parts namely 1. Metal Rim 2. Metal Web 3. Lining (asbestos). Rim is a sheet metal part manufactured by stamping process. Web is also a sheet metal part manufactured by stamping process. Lining is an arch like non metallic molded part made out of asbestos or non asbestos material.

The web is thus a blanked part produced using steel strip using a die and power press. Depending upon the profile and thickness tonnage of press is selected. Usually the thickness of web is twice the rim thickness. In this blanking process hot rolled steel strip is fed into the progressive blanking die and required shape is blanked out by punching process. Around 50% of the input material goes as wastage or scrap.

The rim is a blanked part produced using steel strip and power press. Depending upon the profile and thickness tonnage of press is selected. Usually the thickness of rim is half the thickness of the web, in this blanking process hot rolled steel strip is fed into the progressive blanking die and required shape is blanked out by punching process. Around 15% of the input material goes as wastage or scrap.

After manufacturing of web & rim separately, both the parts are joined by resistance welding or by cold riveting depending upon application, after the rim is joined to web this becomes a metal brake shoe and on the outer profile of the shoe the lining is bonded or riveted depending on the application. During web and rim welding process, rim is formed in radial shape before welding. The brake shoe assembly is vital to augment rib strength and to transmit force from wheel cylinder assembly to hold the brake.

To site an example, in the conventional method of manufacturing web and rim, to manufacture 100 numbers of a typical web, the required raw material input is 100 kgs. Then the output is 60 kgs of web. The wastage or scrap is around ~40%. The similar situation prevails even for rims, the wastage is around ~15%. Hence in such conventional method of manufacturing brake shoes, the percentage of input raw material wasted as scrap is large and poses a great loss to the manufacturer.

The above mentioned conventional method, called blanking operation for web and rim and welding operation for joining parts as brake shoe assembly, is being widely used by the present auto ancillaries and spare parts industries which are engaged in the manufacture of shoe assy.

The concern of all these industries lies in the substantial percentage of waste that is obtained while manufacturing of brake shoe assembly in this conventional style. Therefore is it the need of the hour in the industry to develop a cost effective manufacturing method for brake shoe assembly by reducing the throughput time, increase the inventory turnover, reducing the work in progress

Some of the prior art in this field reveal diverse techniques deals with various kinds of manufacturing methods for brake shoe assemblies and novel brake assemblies.

Indian Patent Application No: IN/PCT/2000/00230/DEL discloses a brake shoe assembly for a drum brake, the brake shoe assembly being a single-piece construction and including a brake shoe of generally circular form having two separate and opposed ends, and defining a pair of friction lining mounting sections disposed on opposite sides of the brake shoe. The friction lining mounting sections have a T-shaped cross-sectional form defining an accurate, radially outer platform for mounting a friction lining and a radially inwardly extending web. The brake shoe including hinge means between the lining mounting sections, facilitating pivoting movement of the lining mounting sections, to alter the separation between the brake ends between a brake operative condition in which in use, the friction lining engages a braking surface of a drum to which the brake shoe assembly is fitted, and a brake inoperative condition in which there is no such engagement. The brake shoe assembling further includes a backing plate depending from the brake shoe in the region of the hinge means for mounting the brake shoe to a brake shoe assembly support..

Indian Patent Application No: 653/DEL/2003 claims a brake shoe assembly that includes the first and second sections defining a lining surface and a mounting tab. The mounting tab extends perpendicular from the lining surface and includes a series of notches allowing the formation of the lining surface into an arcuate shape. The mounting tabs are secured together such that subsequent manufacturing operations to correct distortion are not required. A brake lining is secured to the lining surface.

Indian Patent Application No: 490/CHE/2009 describes a cost-effective manufacturing method for brake shoe webs, in which, individual strips are fed into a comparatively low tonnage hydraulic press and radially formed into the desired shoe web shape due to the descending force of the press. The radially formed strips are then fed into a tool for a second stage of operation of cropping the ends and punching out the holes leading to the formation of final product.

Indian Patent Application No: 3260/CHENP/2008 claims a brake shoe which can be manufactured by a method comprising a reduced number of manufacturing steps, and such a method. A brake shoe 1 is manufactured by cutting a sheet blank formed by extrusion or calender sheeting into strips having a predetermined length, laying the strips on the shoe body 2, pressing and bonding the strips to the shoe body 2 and hardening the strips. The lining 3 is formed with tapered surfaces 4 at both ends thereof for facilitating release of the lining from a die. The lining 3 preferably contains as a binder a rubber that turns into ebonite when subjected vulcanization.

Indian Patent Application No: 1254/MAS/1997 describes a brake shoe for an internal shoe drum that has an arcuate platform (2a, 3a) carrying a lining of friction material (2b, 3b) on its outer face. A web (2c, 3c) extends perpendicularly from the inner face of the platform and provides a shoe tip intended to be supported on an angled surface (7a, 7b) of the brake abutment (7). This shoe tip has a pair of differently directed surface portions (T1, T2).

However none of the existing prior art discloses any manufacturing method of brake shoes whereby input is a single metal sheet which produces a single piece brake shoe.

Therefore is it the need of the hour in the industry to develop a manufacturing method for brake shoes that is cost effective and turns out strong brake shoes that are long lasting.

The present invention attains this objective and addresses the major manufacturing problem of wastage of raw material and usage problem of the wear and tear of a normal brake shoe that consists of separate webs and rims.

The present invention involves a novel manufacturing method whereby, the conventional blanking operation and mechanical press method of manufacturing brake shoe webs and rims and welding operations is eschewed in favor of a

special process called single piece forming process to make a brake shoe assembly, which includes several concise steps and the employment of a hydraulic press and mechanical press to arrive at the final finished product. This will totally eliminate the separate manufacturing of web and rim and joining both the parts by welding operation using high tension electrical power.

As a comparative example, in the present novel manufacturing method, raw material input for 100 shoes is around 100 kgs and the output is 65kgs of shoe and wastage is only 35%. The stages in the manufacturing process and the manufacturing time are also drastically reduced.

Hence the formation process that forms the part of the present invention ensures that maximum percentage of input raw material is converted into product output and the brake shoe assembly is produced in a single piece form. Hence the present invention is a boon to the automobile and spare parts industries for manufacturing brake shoe assy in a single piece form by a cost effective method where the percentage of waste is very minimal, welding operation is totally eliminated and throughput time is reduced drastically. It thus turns out the brake shoe as a single unit that does not require the separate joining of the rim onto the brake shoe and web, thus increasing the strength of the brake shoe.

Further it will be apparent to those skilled in the art that the objects of this invention have been achieved by providing a suitable manufacturing method which is unique in nature unlike existing manufacturing methods for brake shoes. Various changes may be made in and without departing from the concept of the invention. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing and modifying other methods and structures for carrying out the same purpose of the present invention. Further, features of some stages disclosed in this application may be employed with features of other stages. Therefore, the scope of the invention is to be determined by the terminology of the following claims and the legal equivalents thereof.

OBJECTIVES OF THE INVENTION:

This invention may be summarized, at least in part, with reference to its objects.
The foremost object of the present invention is to present a novel manufacturing method for producing a single unit brake shoe assembly combining together the brake shoe, rim and web as a single component.

Another object of the present invention is to provide a cost-effective manufacturing method for producing a single unit brake shoe assembly whereby the number of stages in the entire production process is reduced.

Another object of the present invention is to eliminates the joining by the welding operation in the brake shoe manufacturing process using high tension electrical power or cold riveting operation using special purpose equipment.

Another object of the present invention is to reduce the percentage of scrap from the direct input materials during rim and web manufacturing process.

Another object of the present invention is to increase the strength of the brake shoe due to the manufacturing of the brake shoe as a single unit.

Another object of the present invention is to lessen the wear and tear from the friction and heat generated during brake shoe usage by providing the brake shoe being as a single unit.

Another object of the present invention is to facilitate easy handling of the raw material.
Yet another object of the present invention is maximum utility of the raw material and save input.

A further object of the present invention is to increase the inventory turn ratio by reduce the through put time. Hence this process is thus making the present invention highly suitable as a lean manufacturing method to enable just- in-time manufacturing to the buyers.

Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention.

SUMMARY OF THE INVENTION

The present invention embodies a novel cost effective manufacturing method for the manufacture of highly durable brake shoe assemblies, the present invention manufacturing process eliminates the various steps of separate web stamping operation, separate rim stamping operation, separate rim radius forming operation, joining of both web and rim using resistance welding or by cold riveting operation and shoe truing operation to achieve shoe radius.

DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will be more readily apparent by persons skilled in the art when considered in reference to the following description and when taken in conjunction with the accompanying drawings listed below

Figure 1 is a comparative flow chart illustrating the manufacturing process of the present invention in comparison to the conventional manufacturing method.

Figure 2 is a perspective diagram of the present invention.

DETAILED DESCRIPTION

The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of particular applications of the invention and their requirements. The present invention can be configured as follows:

Brake shoe assembly is a part of the drum brake assembly created by a welding of rim and web. The present innovative manufacturing process envisages the creation of a brake shoe assembly in a single piece by the use of individual strips of steel as raw material, instead of making webs and rims separately and joining both the parts using welding operation. The dimensions of the individual strip may vary according to the shoe assembly being manufactured. The present process and method can be used for the production of a varied range of brake shoe assemblies, for heavy, medium and small vehicles.

In a preferred embodiment of the present invention, as illustrated in Figure 2, to produce the required form of brake shoe assembly, the development length based on radius of the web and rim is measured.

In a preferred embodiment of the present invention, a hydraulic press is used. A mechanical press with the required tool configuration can also be used. The said press contains top and bottom tool assemblies clamped to the machine bed. Individual strips of steel are fed into the press by loading them in the locator provided in the die holder assembly. When the operator initiates the press, the top assembly descends on the strip and the strip is formed using the descending force of the press.

In a preferred embodiment of the present invention, the steel strip (1) undergoes an end cropping operation at all the four corners trimmed as shown in Stage 1 of Figure 2.
In a preferred embodiment of the present invention, the cropped strip is formed into a radial shape in the hydraulic press as shown in Stage 2 of Figure 2.

In a preferred embodiment of the present invention, the radial part is crushed in required shape and the gimp is formed at six places in the hydraulic press as shown in Stage 3 of Figure 2.

In a preferred embodiment of the present invention, the gimp formed part is trimmed at both sides to get required width in Mechanical press as shown in Stage 4 of Figure 2.

In a preferred embodiment of the present invention, the trimmed part is fed into a mechanical press and cropped and punched with a press tool for creating final shoe assembly (2) as shown in Stage 5 of Figure 2.

In a preferred embodiment of the present invention, the punched part is spot welded at both ends of the shoe assy in spot welding machine as shown in Stage 6 of Figure 2.

The individual strips of steel thus undergo various stages of pressing formation and processing through end cropping, forming, crushing, gimp forming and trimming, piercing the holes with a mechanical press to form the brake shoe assembly single piece final product which is subject to the standard quality tests.

The wastage scrap out of the formation stage in the present invention is nil. The wastage scrap out of the end cropping, forming, crushing, gimp forming and trimming, piercing the holes in the innovative process and method is also minimal. This is in contrast to the substantial wastage skeleton scrap that is generated during the conventional process of producing brake shoe webs and rims.

Figure 2 further lays down in detail the comparison in the production of waste scrap in the innovative and present conventional brake shoe assembly production modes.

While there has been shown and described what is considered to be preferred embodiments of the invention, it will, of course, be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention. It is therefore intended that the invention be not limited to the exact forms described and illustrated, but should be constructed to cover all modifications that may fall within the scope of the appended claims.

It will be apparent to those skilled in the art that the objects of this invention have been achieved by providing the above invention. However various changes may be made in the structure of the invention without departing from the concept of the invention. Therefore, the scope of the invention is to be determined by the terminology of the following claims and the legal equivalents thereof.

CLAIMS:

What is claimed is:

1. A novel manufacturing method of a single piece brake shoe comprising of the stages of end cropping, forming, crushing and gimp forming, trimming, piercings and spot welding, characterized in that said method eliminates individual manufacturing of web stamping, rim stamping following different stages, rim radius forming, joining of both web and rim using resistance welding or by cold riveting, and shoe truing.

2. The manufacturing method as claimed in Claim 1 wherein, the development length based on radius of the web and rim is measured to produce the required form of brake shoe assembly.

3. The manufacturing method as claimed in Claim 1 wherein a hydraulic press or a mechanical press with the required tool configuration is used, said press containing top and bottom tool assemblies clamped to the machine bed, individual strips of steel being fed into said press by loading them in the locator provided in the die holder assembly.

4. The manufacturing method as claimed in Claim 1 wherein on initiating said press, said top assembly descends on said steel strip and forms it using the descending force of said press.

5. The manufacturing method as claimed in Claim 1 wherein said steel strip undergoes an end cropping operation at all the four corners.

6. The manufacturing method as claimed in Claim 1 wherein said cropped steel strip is formed into a radial shape and crushed into the required shape in said a press.

7. The manufacturing method as claimed in Claim 1 wherein a gimp is formed at six places on said cropped steel radial part in said in a press and trimmed at both sides to get the required width in said mechanical press.

8. The manufacturing method as claimed in Claim 1 wherein said trimmed gimp formed cropped steel radial part is fed into said mechanical press and cropped and punched with a press tool, said punched part being spot welded at both ends of said shoe assembly in a spot welding machine to create the final shoe assembly.

9. The manufacturing method as claimed in Claim 1 wherein said brake shoe assembly is produced as a single piece without the separate welding of the shoe web onto the shoe rim.

10. The manufacturing method as claimed in Claim 1 wherein for every 100kgs of input, the output is 65 kgs, and wastage is around 35 kgs