Title of Invention

A PROCESS FOR PREPARING COMPOSITE BRAKE BLOCK FOR USE IN RAILWAYS

Abstract

Conventional cast-iron brake blocks lack in durability, resistance to wear and tear, resistance to impact, corrosision and pitting on prolonged exposure to elements. They emit toxic, foul smelling gas on sudden application of brakes. This invention provides a process for preparing composite brake blocks (CBB) for use in railways which comprises (i) mixing the following ingredients by weight (a) brown fused alumina 10-20 %, china clay 20-40 %, plastic clay 25-45 %, gypsum 3-10 % and powdered lime 2-3 % for 60-90 minutes at a temperature between 150° C and 280° C ; (ii) adding 10-15 % by wt. of insulation wool to the mixture (i) and mixing for around 30 mins, (in) adding 10-15 % by wt. of phenoli resin and mixing for 1/2 hour, (iv) polymerizing the mix from (ii) at 250° C - 280° C, (v) pouring the viscous, semi-solid mass from (iv) into moulds, pressing them and (vi) curing the products (CBB) at around 200°C for around 24 to 36 hours.

Full Text

The present invention relates to a process for preparing composite •brake block for use in railways and Morc particularly this invention pertains to a composite brake block ( hereinafter referred to as "CBB" for the sake of brevity) for use in railway carriages, wagons, engines etc., which is wholly non-metallic and is much more durable that the conventional metallic brake blocks. The subject invention is also concerned with a process for preparing CBB. Conventional brake blocks lack durability and resistance to wear and tear. Usually there blocks were and are still being made from cast iron. Apart from being prone to develop crack on impact, brake blocks made from cast iron suffer from another serious disadvantage. It has been observed that on sudden application of brakes, a foul smell is given out which, accordingly to health authorities and particularly World Health Organisation (W.H.O.), is quite toxic and deleterious to human health. Apart from the foregoing, the problem of pilferage is also a source of financial loss of Railways, not to speak of the incidence of corrosion and pilting due to prolonged exposure to wind, sunrays and rail. Such problems confront the Railway Authorities particularly in third world and developing countries. Attempts have been made to find suitable alternative to cast iron to make brake blocks for locos and rolling stock, but they did not meet with much success. Different alloys were tried but none of these proved suitable. Hence a systematic trial and search was launched for finding a suitable soltion to the problems confronting the railways. Eventually an appropriate substitute has been developed by dint of the present invention. The principal object of the present invention is to provide a novel composite brake block for use in railways which is capable of overcoming the difficulties discussed above. A further object of this invention is to provide a process for preparing a composite brake block for use in railways. A still further object of this invention is to provide a process for -making composite brake blocks by using indigeneously available raw materials and equipments. Another object of this invention is to provide a composite brake block which is durable, substantially resistant to wear and tear and cost-effective. The foregoing objcts are achieved by the present invention which relates to a novel composite brake block (CBB) for use in railways comprising in combination the following: (a) brown fused alumina, (b) china clay, (c) plastic clay, (d) gypsum, (e) powdered lime, (f) insulation wool containing limestone and haematite , mixed intimately with phenolic resin in amounts as given hereinafter and allowed to polymerise, moulded, pressed and cured to impart desired shape, size and configuration to the finished article. As used before and hereinafter in this specification, the term "insulation wool" refers to a product obtained by heating a mixture of limestone, haematite and coke in a closed furnace chamber lined inside with magnesia-carbon bricks capable of withstanding temperatures of 1400°C and above. The aforesaid ingredients are properly mixed in the furnace. After around 30 minutes, temperature is gradually raised to above 1400°C whereby both limestone and haematite melt and the molten mass is poured in a rotating drum. Water is sprayed on the molten mass resulting in formation of insulation wool', which is partially a good conductor. This invention pertains to a process for preparing a composite brake block (CBB) for use in railways, which comprises - 3 (i) mixing the following ingredients in proportions shown against each one of them - (a) brown fused alumina - 10 - 20 % by weight, (b) china clay - -20 - 40 % by weight, (c) plastic clay - 25 - 45 % by weight, (d) gypsum - 3 - 10 % by weight, and (e) powdered lime - 2 - 3 % by weight, in a rotary mixing machine equipped with heating arrangement for a period of 60 to 90 minutes at a temperature between 150° C and 280° C ; (ii) adding insulation wool in an amount of around 10 -15 % by weight and again rotating the mixture for around 30 minutes ; (iii) adding phenolic resin of desired grade such as herein described in an amount varying between 10 % and 15 % by weight to the mass obtained from step (ii) and continuing mixing for more than an hour; (iv) transferring the mixture from step (iii) in a suitable reaction vessel to allow polymerization reaction to take place at temperature between 250° C and 280° C; (v) pouring the semi-solid, viscous mass into moulds and pressing the mass in a hydraulic press to attain dimensions such as herein described and (vi) curing the final products (CBB) at a temperature of around 200° C for a period of around 24 to 36 hours. For instance, alumina (A1203) content and particle size of different ingredients should be as follows : Content Size (i) fused alumina - around 70 % - 90 % > 30-100 mesh (ii) china clay -around 25%- > 250-300 mesh (iii) plastic clay - around 30 % - > 150 - 300 mesh (iv) gypsum - traces, - -, and powdered lime - 80 % - 92.5 % of CaO. 4 In the process of the present invention there is used a special variety of phenolic resin prepared by us for binding the ingredients by polymerization resulting in friction - resistant solid shaped materials. The resin has the following ingredients present in amounts indicated against each one of them, as given below: i) starch - 15 - 20% by wt, ii) plastic clay - 15 - 20% by wt, iii) molassses - 25 - 30% by wt, iv) refined mobil oil - 5 - 10% by wt, v) natural rubber solution - 5 - 10% by wt, vi) phenol (40 - 45% by wt) - 25 - 35%. by wt The ingredients are intimately mixed in a mechanical mixer, such as a counter - current mixing machine, for around 25 to 30 mins and then the temperature is raised to 90°C - 110°C and the mixture is held at that temperature for around 1 hour. The temperature is gradually brought down to ambient and the mixture is allowed to stand for 9 - 12 hours to complete the polymerization reaction. The phenolic resin used in the present invention possesses the following characteristics: (i) specific gravity of the resin - 1.6 gm/c.c. (ii) viscosity of the resin - 7000 c.p.u. (iii) moisture content - 0.12 (iv) T.A.N. (Total acid no.) - 6 and (v) flash point - 300° C The constituent ingredients are mixed in a rotary mixing machine operated at around 3000 RPM for at least one hour at an elevated temperatur of around 180° C to 200° C. Final mixing of all ingredients including resin i condusted in a Muller mixer maintained at around 180° C to attain desire degree of viscosity. The viscous mass obtained at the end of final mixing at an elevated temperature is transferred to moulds to impart desired shape, size and configuration which are then pressed by hydraulic press, usually at an elevated temperature. The final products ( CBB ) are released from moulds and then cures by soaking in steam for around 6 hours. The invention will now be more particularly illustrated by means of the accompanying drawings in which - Fig. 1 : gives a sectional view of CBB along section -BB, Fig. 2: is a schematic diagram of the brake block showing section line BB, and Fig. 3: is a sectional view of the block along section -AA In Fig. 1,(1) is M.S. cassete, i.e. back plate of CBB, (2) in the fixing clamp and (3) illustrates thickness of CBB. In Fig. 2, there is illustrated a top view of the article of this inventior wherein (1) and (2) have the same significance as given above. Fig. 3, shows a partial sectional view of CBB including the fixing clamp (2) and a partial view of one end of the block. The subject invention will now be further amplified by the following example which is given by way of illustration and not by way of limitation. Example. CBB is fabricated by mixing intimately the undernoted ingredients in amounts shown against each one of them : (i) Brown fused alumina - 20%by wt (ii) China clay - 20 % by wt (iii) Plastic clay - 25 % by wt (iv) Gypsum - - 10 % by wt (v) Insulation wool - 15 % by wt Mixing is usually done in a ball mill or a rotary mixing machine operating at around 3000 r.p.m. at ambient temperature. The mixing machine is equipped with heating arrangement. The mixture thus obtained is thereafter intimately mixed with requisite amount of phenolic resin which will bind the above ingredients. The mixture is again rotated in the Muller mixing machine for around 1 hour, slowly raising the temperature from ambient to 180° - 200° C, and then placed in a reaction vessel for polymerization reaction to take place. The final composition mixture in a semi-solid form is placed in suitable moulds and pressed in a hydraulic press. The shaped products are cured at an elevated temperature of around 200° C over a predetermined period of time. The dimensions of the final products are given below. It is to be noted that such dimensions are mainly determined by the specifications as laid down by the Railway Board. (a) M. S, Casette, i.e. Back Plate of C.B.B. : Length - 300 mm, Width - 76 ±2 mm (b) Thickness of the back plate clamp - 4-5 mm 2. Fixing Clamp: (i) 32 mm wide & 32 mm long (ii) 30 mm wide & 30 mm long 3. Thickness of C.B.B. - 61.5 mm - 62.5 mm Width - 72 mm From a charge of 2 MT, 444 numbers of C.B.B. can be fabricated for use in carriage of E.M.U. coaches, and 363 numbers of C.B.B. can be fabricated for use in loco. While the invention has been described in detail and with specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without deviating or departing from the spirit and scope of the invention. Thus the foregoing disclosure includes within its ambit the obvious equivalents and substitutes as well. Having described the invention in detail with particular reference to the illustrative example and drawing, it will now be more specifically defined by means of claims appended hereafter. We claim : 1. A process for preparing composite brake block (CBB) for use in railways which comprises - (i) mixing the following ingredients in proportions shown against each one of them - (a) brown fused alumina - 10-20 % by weight, (b) china clay - 20-40 % by weight, (c) plastic clay - 25-45 % by weight, (d) gypsum - 3 - 10 % by weight, and (e) powdered lime - 2 - 3 % by weight, in a rotary mixing machine equipped with heating arrangcment for a period of 60 to 90 minutes at a temperature between 150°C and 280° C ; (ii) adding insulation wool in an amount of around 10 - 15 % by weight and again rotating the mixture for around 30 minutes ; (iii) adding phenolic resin of desired grade such as herein described in an amount varying between 10 % and 15 % by weight to the mass obtained from step (ii) and continuing mixing for more than an hour ; (iv) transferring the mixture from step (in) in a suitable reaction vessel to allow polymerization reaction to take place at temperatures between 250° C and 280° C ; (v) pouring the semi-solid, viscous mass into moulds and pressing the mass in a hydraulic press to attain dimensions such as herein described, and (vi) curing the final products (CBB) at a temperature of around 200° C for a period of around 24 to 36 hours. 2. A process as claimed in Claim 1, wherein the rotary mixing machine is operated at around 3000 r.p.m. for at least one hour at a temperature of between 180° C and 200° C. 3. A process as claimed in Claim 1, wherein curing of the final products (CBB) is carried out by soaking in steam for around 6 hours. 4. A process as claimed in Claims 1 to 3, wherein alumina (Al2O3) content of (reckoned by wt.) : (i) brown fused alumina is around 70 % - 90 %, (ii) china clay is around 25 %, (iii) plastic clay is around 30 %, (iv) gypsum is negligible, and CaO content of powdered lime varies between 80 and 92.5 %. 5. A process as claimed in Claims 1 to 4, wherein preferred particle sizes of the CBB ingredients are as follows : (i) fused alumina - 30 - 100 mesh (ii) china clay - 250 - 300 mesh and (iii) plastic clay - 150 - 300, respectively. 6. A process as claimed in Claim 1, wherein the phenolic resin used in steps (iii) and (iv) thereof has the undernoted characteristics : (i) specific gravity - 1.6gm/cm3, (ii) viscosity - 7000 C.P.U. , (iii) moisture content - 0.12, (iv) T.A.N (total acid no.) - 6 and (v) flash point 300° C. 7. A process as claimed in any one of the preceding claims, wherein final mixing of all the ingredients in carried out in a Muller mixer maintained at around 180° C to 200° C till the entire mass turns into a fluid state. 8. A process for preparing a composite brake block (CBB), for use in railways, substantially as hereinbefore described with particular reference to the appended Example. Conventional cast-iron brake blocks lack in durability, resistance to wear and tear, resistance to impact, corrosision and pitting on prolonged exposure to elements. They emit toxic, foul smelling gas on sudden application of brakes. This invention provides a process for preparing composite brake blocks (CBB) for use in railways which comprises (i) mixing the following ingredients by weight (a) brown fused alumina 10-20 %, china clay 20-40 %, plastic clay 25-45 %, gypsum 3-10 % and powdered lime 2-3 % for 60-90 minutes at a temperature between 150° C and 280° C ; (ii) adding 10-15 % by wt. of insulation wool to the mixture (i) and mixing for around 30 mins, (in) adding 10-15 % by wt. of phenoli resin and mixing for 1/2 hour, (iv) polymerizing the mix from (ii) at 250° C - 280° C, (v) pouring the viscous, semi-solid mass from (iv) into moulds, pressing them and (vi) curing the products (CBB) at around 200°C for around 24 to 36 hours.

Documents:

00429-kol-2003-abstract.pdf

00429-kol-2003-claims.pdf

00429-kol-2003-correspondence.pdf

00429-kol-2003-description(complete).pdf

00429-kol-2003-drawings.pdf

00429-kol-2003-form-1.pdf

00429-kol-2003-form-18.pdf

00429-kol-2003-form-2.pdf

00429-kol-2003-form-3.pdf

00429-kol-2003-letters patent.pdf

00429-kol-2003-p.a.pdf