Title of Invention	A METHOD FOR THE MANUFACTURE OF AN ELASTOMERIC PAD
Abstract	An elastomeric pad comprising three metal plates bonded with rubber compound ; the top metal plate (A) has a V shaped projection in its bondable area which when bonded with rubber compound forms a uniform layers, middle plate (B) has two angles, one at the center and the other is at the contour and third plate (C) is totally flat.

Full Text

TITLE: MANUFACTURE OF AN ELASTOMERIC PAD This Invention relates to a manufacture of an elastomeric pad, This invention also relates to the formulation and the preparation of rubber which is used In the said pad. Elastomeric pads are metal bonded rubber pad used in Indian Railways as a shock absorber to protect the bogie and rail from damage under service condition. Eight number of rubber pads are used for each bogie which is placed between side frame and adapter. It is subjected to compressive and shear forces of the order of 15 and 04 tones respectively under dynamic condition. Previously, the pad was manufacture by Research Design & Standard Organisation (RDSO), Ministry of Railways, Lucknow which had abnormally short life resulting in huge annual loss of Indian Railways in respect of material and labour cost due to replacement of those pads. Initially, the pads consisted of two metal plates which could not prevent the positive bulging and flex crack of rubber. Also in the previous product the possibility of bond failure and stress relaxation in shear remains. Further,when the train brakes the wagon has a tendency to move forward due to its kinetic energy and the known pads are not manufactured to stop or reduce such movement. Thus, to overcome the shortcomings, the novel design and formulation of the present invention was proposed. An object of this invention is to propose an elastomeric pad with a novel design. Another object of this invention is to propose an elastomeric pad with a high flex and fatigue resistant rubber compound. Still another object of this invention is propose a novel composition of the rubber compound. Yet another object of this invention is to propose preparation of rubber compound. According to this invention, there is provided en elestomertc pad comprising three metal plates bonded with rubber compound; the top metal plate (A) has a "V" shapped projection in its bondable area which when bonded with rubber compound forms a uniform layers, middle plate (B) has two angles, one at the center and the other Is at the contour and third plate (C) is totally flat. This invention also relates to the preparation of the rubber compound comprising: preparing master batch by mixing natural rubber (smoke sheet) and other ingredients; dividing the said master batch into 3 equal parts; mixing each part with curative/s; extruding each part through a twin-screw extruder; cooling said extrudate; introducing said cooled extrudate into a 2-roll calender machine to produce sheets; cutting said sheets to desired size. The invention will be described in greater detail herein after with reference to accompanying drawings. Figure 1 povides the produce having metal plates bonded with rubber compound. The top metal plate (A) has a projected "V" shape part in its bondable area, the middle plate (B) has two angles, one at the center and the other is at the contour. The third plate (C) is totally flat. Figure 2 depicts that in the second layer of rubber the middle plate gives very high stiffness at the center with lower plate (C), but the ends are of low stiffness value. The elastomeric pad of the instant invention has 3 layers, the top plate makes a uniform layer of uniform stress distribution with the second plate except at the end where stiffness is quite higher than the middle. In the second layer of rubber, the middle plate gives very high stiffness at the center with the third and the lowest plate but the ends are of low stiffness value. In the proposed design, the middle plate is at an angle of 160° which gives a parallel surface to the projected part of upper plate. As as result, the lower plate makes an angle of 10° in both sides of middle plates. Radius of rubber curvature had been changed from old design and has been made 10R for upper and 18R for lower part. Under dynamic condition, the middle part of the top rubber layer will act as a shock absorbing membrane and the side end parts of that top layer will absorb a part of the shock and also will transfer the rest shock to its just next lower portion at second layer where stiffness is low compared to the middle part of that layer. When functioning, the high stiffness zones of the elastomeric pad are being deflected under load to about 25% of total deflection and acts as a Primary Suspension. Accordingly, the low stiffness zones being deflected to about 75% of total deflection and acts as a Secondary Suspension. Moreover, the side ends of middle plate will act as a flexible wing also (Fig.3). As a result, the stress concentration at the side end of the top rubber layer will be distributed into those two top and bottom layers. When the train brakes, the wagon has a tendency to move forward due to its kinetic energy. The proposed design restricts the wagon to move forward when braking. The detailed process for the manufacture of elastomeric pad comprises the following steps: preparing the master batch in a dispersion knidder by mixing natural rubber (smoke sheet IX), polybutadiene rubber and other ingredients such as stearic acid, wood rosin, zinc oxide, antioxidant such as 2,2,4-trimethyl quinoline (TMQ), N-butyl- N-isopropyl paraphenylene diamine (6PPD), high abrasion furnace black (HAF) and semi-reinforcing furnace black (SRF) at 6 kg/sq cm pneumatic pressure for 10 minutes; dividing said master batch into 3 equal parts; mixing each part with curative like N-cyclohexyl 2 benzothiazole-sulphenamide (CBS), extruding each part through a twin-screw extruder, cooling the extrudate introducing said extrudate to a 2-roll calender to get the rubber sheets of uniform thickness; cutting said sheets by automatic pneumatic cutter to obtain the desired size and length; treating 3 plates of mild steel with 10% HCl at room temperature for 10 minutes and drying the same; shot blasting the said metal sheets by using steel shots; coating the said blasted metal surface with two layers of adhesive, i.e one coat of primer bonding adhesive and two coats of cover bonding adhesive; fixing the rubber compound between the metal layers, i.e between first and second metal plates and second and third metal plates; curing the metal bonded rubber pad in a transfer/compression moulding press at 140°C-150°C for 25 minutes; cooling the cured product for 24 hours; cutting the extra flashes of the pad by using scissors and knife; and painting the exposed metallic parts of the elastomeric pad with anti-corrosive paint. In accordance with this invention there is provided a process of manufacturing elastomeric pad comprising mixing 100 gms of elastomers, 3-5 gms of antioxidant per hundred gms of elastomer, 45-55 gms of high abrasion furnace black per hundred gms of elastomer, 35-25 gms of semi-reinforcing furnace black (SRF) per hundred gms of elastomer, and 8.50-12.50 gms of other ingredients per hundred gms of elastomer, under 6 kg/sq cm pneumatic pressure for 10 minutes; dividing said master batch into 3 equal parts; mixing each part with curative like N-cyclohexyl 2 benzothiazole-sulphenamide (CBS), extruding each part through a twin-screw extruder, cooling the extrudate, introducing said extrudate to a 2-roll calender to get the rubber sheets of uniform thickness; cutting said sheets by automatic pneumatic cutter to obtain the desired size and length; treating 3 plates of mild steel with 10% HC1 at room temperature for 10 minutes and drying the same; shot blasting the said metal sheets by using steel shots; coating the said blasted metal surface with two layers of adhesive, i.e one coat of primer bonding adhesive and two coats of cover bonding adhesive; fixing the rubber compound between the metal layers, i.e between first and second metal plates and second and third metal plates; curing the metal bonded rubber pad in a transfer/compression moulding press at 140°C-150°C for 25 minutes; Transfer moulding process is done at 60 tons clamping force and 50 tons, transfer force; Compression moulding process is done at 80 to 100 tons force; cooling the cured product for 24 hours; cutting the extra flashes of the pad by using scissors and knife; and painting the exposed metallic parts of the elastomeric pad with anticorrosive paint. Degreasing of metal plates by mixing sodium hydroxide. EXAMPLE The formulation of the rubber compound is as follows: Ingredients Parts per hundred of elastomer (Phr) Natural rubber (NR) (Smoke sheet IX) 90.00 gms elastomer Cis 1,4 Polybutadiene 10.00 gms " Searic Acid 1.50 gms Wood Rosin 2.00 gms Zinc Oxide 7.00 gms Trimethyl qulnoline (TMQ) (Antioxldant) 2.00 gms N-phenyl-Isopropyl-paraphenylene dlamine 2.00 gms (6PPD) HAF Carbon Black 50.00gms SRF Carbon Black 30.00 gms N-cyclohexyl 2 benzothlazole-sulphenemide 00.70 gms Sulphur 02.60gms WE CLAIM: 1. An elestomerlc pad comprising three metal plates bonded with rubber compound, the upper metal plate has a "V" shapped projection in Its bondable area which when bonded with rubber compound forms a uniform layer, middle plate has two angles, one angle is at the center and the other Is at the contour, and the lower plate is completely flat. 2. The elastomeric pad as claimed in claim 1, wherein the middle plate Is at an angle of 160o which gives a parallel surface to the projected part of upper plate. 3. The elastomertc pad as claimed in claim 1, wherein the lower plate makes an angle of 10° in both sides of middle plates. 4. A method for the manufacture of elastomeric pad as claimed in claim 1 comprising the steps of: mixing of elastomers, anti-oxidant, high abrasion furnace black (HAF), semi-reinforcing furnace black (SRF) and other ingredients under pressure to produce the master batch; dividing the said master batch into 3 equal parts; mixing each part with curative; extruding each part through a twin-screw extruder; cooling the extrudate; introducing said cooled extrudate to a 2-roll calender to get the rubber sheets of uniform thickness; cutting said uniform sheets by a cutter to obtain the rubber sheet of desired size and length; degreasing of metal plates by using an alkali; treating 3 plates of mild steel with an acid at room temperature and drying the same; shot blasting the said metal surface with steel shots; coating the said blasted metal surface with an adhesive; fixing the rubber sheet between the metal layers; curing the metal bonded rubber pad; cooling the cured product for 24 hours; cutting the extra flashes of the pad. 5. A process as claimed in claim 4, wherein the said alkali is NaOH. 6. A process as claimed in claim 4, wherein the said elastomer is a blend of natural rubber and polybutadiene. 7. A process as claimed in claim 4, wherein the other ingredients are stearic acid, wood rosin and zinc oxide. 8. A process as claimed in claim 4, wherein the said anti-oxidant is a mixture of 2,2,4-trimethyl guinoline and N-butyl-N-isopropyl paraphenylene diamine. 9. A process as claimed in claim 4, wherein the pressure required is a 6 Kg/sq cm. 10. A process as claimed in claim 1, wherein the master batch is prepared in a dispersion knidder. 11. A process as claimed in claim 4, wherein the rubber sheet are cut in a automatic pneumatic cutter. 12. A process as claimed in claim 4, wherein the extruder is a twin-screw extruder. 13. A process as claimed in claim 4, wherein the mild steel is treated with 10% HC1 - 30% HC1. 14. A process as claimed in claim 4, wherein the mild steel is treated with 10% Hcl. 15. A process as claimed in claim 4, wherein the said blasted metal surface is coated with one coat of primer and two coats of cover bonding adhesive. 16. A process as claimed in claim 4, wherein the rubber sheet is place between first and second metal plates and second and third plates. 17. A process as claimed in claim 4, wherein the metal bonded rubber pad is cured either by transfer moulding process or by compression moulding process. 18. A process as claimed in claim 17, wherein the curing is done in a transfer moulding process at a temperature of 140-150°C for 25 minutes at 60 tons clamping force and 50 tons transfer force. 19. A process as claimed in claim17, wherein curing is done in a compression moulding process at a temperature of 140-150°C at 80 to 100 tons force. 20. A process as claimed in claim 17, wherein curing is preferably done at a temperature of 14Q-145°C. 21. A process as claime in claim 4, wherein optionally the exposed metallic parts of the elastomeric pad is painted with an anti-corrosive paint. An elastomeric pad comprising three metal plates bonded with rubber compound; the top metal plate (A) has a "V" shaped projection in its bondable area which when bonded with rubber compound forms a uniform layers, middle plate (B) has two angles, one at the center and the other is at the contour and third plate (C) is totally flat.

Documents:

01527-cal-1998-abstract.pdf

01527-cal-1998-claims.pdf

01527-cal-1998-correspondence.pdf

01527-cal-1998-description (complete).pdf

01527-cal-1998-description (provisional).pdf

01527-cal-1998-drawings.pdf

01527-cal-1998-form 1.pdf

01527-cal-1998-form 13.pdf

01527-cal-1998-form 18.pdf

01527-cal-1998-form 2.pdf

01527-cal-1998-form 3.pdf

01527-cal-1998-form 5.pdf

01527-cal-1998-gpa.pdf

01527-cal-1998-letter patent.pdf

01527-cal-1998-reply f.e.r.pdf