|Title of Invention||
"ELASTIC RAIL CLIP USED FOR HOLDING RAIL WITH THE SLEEPER ON RAILWAY TRACK"
|Abstract||Wherein 23 mm spring steel bars have been used. Portion DC of figure I is kept 20.64 mm to suit existing concrete sleeper by turning and junction of two different diameter is made smooth in form of taper and shown by portion CB. The diameter of remaining portion BA is kept as 23 mm. The clip is manufactured from spring steel rod by hot forming and heat treated subsequently to get required physical and metallurgical properties. The clip is capable to provide toe load in the range of 1200 -1500 kg at toe deflection of 13.5mm The clip is capable to bear additional stress / vibration induced in the track due to introduction of higher speed and higher axle load. The clip can be provided on existing assembly.|
|Full Text||The present invention relates to elastic rail clip used for holding rail with the
sleeper on railway track.
The invention is a new design of elastic rail clip named as Elastic Rail Clip MK-V for holding rail more firmly in position with the concrete sleeper as per requirements of modern Indian Railway track i.e. adequate toe load with minimum stresses.
Presently, elastic rail clip Mark-Ill is used in Indian Railways as per drawing enclosed as figure -2. Elastic rail clip Mark-Ill (ERC MK-III) offers a toe load in the range of 850-1100 kg at toe deflection of 13.5 mm. The toe load provided by Elastic Rail Clip Mark-Ill gets reduced in service due to wear of liners, rubber pad, manufacturing tolerances in the components and losing of elasticity of clips. Average toe load available in the field is about 700 kg. Due to introduction of higher axle load and high speed, Indian Railway needs a clip with higher toe load than present to counter the additional forces developed.
In order to overcome the above issues, a project was taken up by RDSO in consultation with IIT/New Delhi for optimisation of shape of different elastic rail clips including ERC Mk-III. The shape of ERC's was generated on mathematical model at IIT/New Delhi. Several shapes with modifications to initial shape of ERC's were analysed on computer through FEM analysis. The results of analysis indicated that with slight change in shape of ERC's, stresses induced in them were quite high. With increase of toe load in existing shapes of ERC's, corresponding stresses developed reached to the plastic limit / deformation to the clip. Therefore, it was concluded by the studies at IIT/New Delhi that requirement of higher toe load can be achieved only by increasing the dia of the existing clip bar. Report of IIT/New Delhi is enclosed at Annexure-II. As there was a limitation for use of increased dia of clip on the existing Indian Railway track, a new design of elastic rail clip called Elastic Rail Clip Mk-V (ERC Mk-V) to suit the existing assembly of Indian Railway track was developed by Research Designs and Standards Organisation, Lucknow.
A fresh consultancy project for FEM analysis of ERC MK-V was taken up at IIT/New Delhi in consultation with RDSO. A mathematical model for required / designed toe load was generated. Corresponding stresses with required toe load were found low as compared to existing ERC MK-III clip. The results of this analysis showed that new clip offers toe load in the range of 1200 - 1500 kg at the design deflection of 13.5mm which was also verified on prototype samples. This clip has lower stresses at the design deflection and has higher elastic cushion beyond the design deflection than
the existing clip being used in Indian Railways, to meet the accidental
stresses. Report of IIT/New Delhi is enclosed at Annexure-III.
Brief description of the drawings :
Fig: 1 shows elastic rail clip used for holding rail with the sleeper on railway track as per present invention.
Fig 2: shows elastic rail clip, presently in use (prior art)
Statement of Invention:
Elastic Rail Clip for holding the rail with concrete sleeper comprising metal rod body having diameter of 23mm, central leg portion (DC) is reduced to 20.64mm for the length of 82mm to suit the existing concrete sleeper, junction (CB) of the different diameters is made in the form of taper portion, remaining portion (AB) of metail rod having diameter of 23mm, toe portion of the clip having elliptical shape of bottom of the metal rod to provide pressure on rail foot on larger area at deflected condition, heel portion opposite to toe of clip rests on plane surface of insert to take reaction from the said surface.
Figure -1 shows the drawings of invention. 23 mm diameter bar has been used for manufacture of this clip. Diameter of central leg portion i.e. DC is kept as 20.64 mm, making it to suit the existing concrete sleeper. The junction of two different diameters is made smooth in the form of taper and shown as portion CB of the drawing. The diameter of remaining portion AB is kept as 23 mm. Portion of clip that exert toe load of the clip on rail foot is made elliptical of size 35 mm x 12 mm.
Elastic Rail Clip for holding the rail with the concrete sleeper comprising of metal rod body of grade 55 Si 7 of IS:3195 having diameter 23 mm. The central leg portion of the clip i.e. portion DC of figure-I is reduced to 20.64 mm for the length of 75 mm. Portion CB in the length of 8mm is made taper to join diameter 20.64 mm to 23 mm smoothly. Toe portion of the clip is having elliptical shape at bottom to provide pressure on the rail foot at deflected condition. Heel i.e. opposite to toe of the clip rests on plane surface of insert to take reaction from the surface. The clip is capable to provide toe load in the range of 1200 - 1500 kg at toe deflection of 13.5 mm with extra margin of toe deflection upto 4-5 mm without permanent deformation to the clip. At 13.5 mm deflection the stresses induced in the clip are in order of 129 kg/mm2.
The clip has been designed using 23 mm diameter of silico manganese spring steel rolled bar of grade 55 Si 7 of IS-3195. Portion of the clip which enters in the eye of insert of existing concrete sleeper has been made by turning it to
20.64 mm diameter by using hydrocopying machine before forming the clip.
These clips are manufactured by hot forming in desired shape and subsequently heat treated by oil quenching and tempering to get required hardness. Details of physical and metallurgical properties of Elastic Rail Clip Mark-V are given as under:-
a) Diameter of clip - 23 mm and 20.64mm for portion
entering in the insert eye
b) Toe load - 1200-1500 kg
c) Toe Deflection - 13.5 mm
d) Hardness - 40-44 RC
e) Approximate weight - 1.08 Kg
f) Shape - As given in the Fig. 1
The length and diameter of the central leg portion, which enters in the insert eye are made as 82 mm and 20.64 mm respectively. Tapered length from 23 mm to 20.64 mm diameter is kept as 8 mm. The size of flat through clip exerts toe load of 1200 - 1500 kg is kept on 35 mm x 12 mm in elliptical shape.
Elastic rail clip mark-V offers toe load in the range of 1200 - 1500 kg at design deflection of 13.5 mm. In the design, margin for extra deflection of 4 to 5 mm above the design deflection has been provided before the clip undergoes to plastic deformation. There is no permanent set up to 16.7 mm deflection which makes the clip enable to bear accidental stresses.
Manufacturing. Quality Control JProcess and Inspection:
For Industrial production, the manufacture & quality control process are as under :-
It covers the technical specification, and provides guidance for production of Elastic Rail Clips. This also covers the technical requirement, inspection and testing procedure of Elastic Rail Clip Mark-V (ERC Mk-V), hereinafter referred as 'clips' which call for stricter control in the quality of raw material, testing standards for implementation of quality assurance programme
This standard refers to the following Indian Standard of BIS.
IS: 77-1976 Linseed oil, boiled for paints.
IS:228(part 1):1987 Determination of Carbon by volumetric method (for
Carbon 0.05 to 2.50 percent.)
IS: 228(part2): 1987 Determination of Manganese in plain carbon and low
alloy steels by arsenite method. IS: 228 (part 8): 1975 Determination of Silicon by Gravimetric method (for
Silicon greater than or equal to 0.1 percent) IS: 228 (part 3): 1987 Determination of Phosphorus by Alkalimetric method. IS: 228(part9): 1975 Determination of Sulphur in plain carbon steels by
IS: 1500- 1983 Method for Brinell hardness test for metallic materials
IS: 1501 (part 1) : Method for Vickers Hardness Test for metallic
IS: 1586-1968 Method for Rockwell Hardness Test (B&C scale ) for
IS:2500( part-I) : Sampling Inspection tables.
1973 Inspection by Attributes and by count of defects (First
IS:2853 - 1964 Method of determining Austenitic grain size of steel
(Amendment no. 1)
IS:3195- 1992 Steel for the manufacture of volute and helical springs
(For Railway Rolling stock)- specification (Third
IS:4163-1982 Method of determination of inclusion content in steel by
microscopic method (First revision)
IS:6396- 1983 Method of measuring decarburised depth of steel (First
IS: 7739- part V- Code of practice for preparation of metallographic
1976 specimen, part V iron and steel and their examination.
A reference to the specification quoted herein after shall be taken in reference to above specifications.
The specific provision in this specification will over-ride those in the above specifications, where these are not in conformity with one another. Any special requirements given in the drawing of the clips will override the relevant provisions of this specification.
Raw Material Procurement
23mm dia spring steel rounds to IS: 3195 shall be procured fi-om RDSO approved manufacturers only.
Technical Specification of the Raw Material
Silico Manganese spring steel as rolled bars to Grade 55 Si 7 of IS: 3195-1992 shall be used in the manufacture of clips. The technical specification of
as rolled steel bars relate to supply condition of the bars in the as rolled and
straightened condition for hot forming.
Manufacturing process for Steel
Steel shall be manufactured by any process of steel making except the Bessemer process. It shall be followed by secondary refining or vacuum melting.
The size of ingots, billets or continuous cast billets for any given size of finished steel product shall be such that a minimum reduction ratio of 16:1 from the minimum cross sectional area of the ingots billet or continuous cast billets to the maximum cross sectional area of the product is ensured.
The Ladle analysis of the steel for the as rolled bars shall conform to following chemical composition as given in IS:3195 for grade 55 Si 7 when tested in accordance with IS:228 or spectrographically.
Carbon 0.50 - 0.60 %
Manganese 0.80- 1.0%
Sulphur 0.04(max) %
Phosphorus 0.04 (max) %
The variation for the product analysis shall be within the following permissible range over Ladle sample analysis:
Element Permissible variation
Carbon + 0.03 %
Manganese ±0.04 %
Silicon + 0.03 %
Sulphur + 0.005 %
Phosphorus + 0.005 %
The grain size of steel shall be 6 or finer as per IS: 2853-1964.
The inclusion rating when determined as per IS: 4163-1982 shall not be worse than 2.5 A, B, C, D both for thick and thin series given at fig. 2 of IS: 4163-1982.
The hardness of as rolled bars when tested in accordance with IS: 1500-1983, the average of three readings shall be approximately 270 BHN or its equivalent in RC of HV scales. This value is for general guidance only.
Depth of Decarburisation
The average total depth of decarburisation (partial + complete ) tested in accordance with IS: 6396-1983 with magnification of XlOO of 5 deepest decarburised zones shall not be more than 0.15 mm.
Freedom from defects
The surface of the as rolled bars shall be reasonably smooth and free from distortion, twist and kinks, and shall be substantially straight.
The as rolled bars shall be free from harmful defects namely folds, laps, cracks, deep pits, grooves, excessive scaling which may lead to cracking during hardening or impair the serviceability. However, the seam size upto 0.25 mm may be permitted in "As-rolled Bars". It shall, however, to be ensured that during the inspection of the raw material, a strict vigil is maintained. The material shall be free from harmful internal defects, such as piping and segregation, which may impair serviceability.
Section of as rolled bars shall be as per order. The tolerance on the diameter shall be +1.0% and -0.8%.
The bars supplied shall also be distinctly marked with paint at the extreme end with different colours to be related with the heat number of material. The bars of different heats shall not be mixed up and shall be stored in stacks heat- wise. Test certificate and raw material checking
The test certificate issued by the producer of steel bars shall bear following
(i) Heat number and Grade
(ii) Colour code
(iii) Chemical analysis
(iv) Inclusion rating
(v) Grain size
(vi) Depth of decarburisation (C,P & T)
(vii) Freedom from harmful defects
(x) Weight of consignment.
The bars shall be checked for the properties (iii) to (ix) above at the rate of two sample bars per heat, (except for the diameter of the bar ) and 20 sample bars per heat for the diameter. The observations shall be compared with the test certificate and shall be examined for acceptability with respect to specification for raw material before its use in the manufacture of clips.
Manufacture of clips
The ERC Mk-V, shall be manufactured from rolled silico-manganese spring steel rounds of 23mm dia by hot forming and shall be subsequently oil hardened and tempered to give uniform hardness across the section. The clips shall conform to the requirements of the relevant drawing and tests stipulated hereinafter. To keep the central leg portion to suit existing design of sleeper, diameter in the central leg portion shall be reduced to 20.64 mm. This shall be achieved by precise profiling using machine like Hydro Copying turning machine to avoid sharp edges/ curves.
Lot and sample size for testing
For the purpose of testing the number of clips manufactured from the same heat and heat treated in a similar manner will form one 'lot'.
For hardness test, dimensional check, application and deflection test and toe load tests, the sample size and the acceptance and rejection numbers for Inspection Level IV and AQL of 1.5 percent shall be as per IS: 2500 (part I) 1973.
For chemical analysis, depth of decarburisation, freedom from defects, and inclusion rating, the sample size shall be as given under relevant clause. The test samples for different tests shall be drawn at random from each lot.
One sample clip drawn from the production of each lot shall be tested for chemical analysis for determination of Carbon, Silicon, Manganese, Sulphur
and Phosphorus as per relevant part number of IS: 228 or the sample shall be
spectrographically analysed. The sample shall conform to the requirement of chemical composition stipulated above with permissible variation. If the chemical composition does not conform to the specified chemical composition, the lot shall be rejected.
The sample clips shall be tested for hardness in accordance with IS: 1586-1968 'Rockwell Hardness Test (B&C Scales) for steels' or IS:1501 (part-I)-1984 "Vickers Hardness Test for Steel" or 18:1500-1983 "Brinell Hardness Test for Steel" and shall conform to the following requirements as the case may be :
Hardness Hardness Number
For decarburisation test, the sample clips shall be microscopically examined at magnification x 100 for decarburisation as per IS:6396-1983. The average total depth of decarburisation (partial + complete) of five deepest decarburised zones of each sample clip shall not be more than 0.25 mm for acceptance of material.
Sample size will be 5% of that for Hardness Test, and the sample clips drawn accordingly will constitute the first sample.
All the sample clips tested in the first sample must pass the test for acceptance of the lot. In case, more than one clip fails, the lot will be rejected. If only one clip fails in the first sample, a second sample of clips will be drawn such that the sample size is twice the sample size of the first sample. All the clips in the second sample of clips should be tested and each clip should pass the test for acceptance of the lot, i.e. in case one clip fails the lot will be rejected.
Freedom from defects
Sample clips will be checked for freedom from defects and should be free from harmful surface defects such as seams, laps, rough or jagged and imperfect edges. The sample clips shall also be examined for the heterogeneity of steel and freedom from internal defects by the micro-etching process as per IS:7739 (Part V) 1976.
Examination of Micro Structure
One sample clip drawn from each day's production heat treated in similar manner (subject to maximum of 10,000 numbers of clips) shall be subjected to micro examination. Sample prepared for micro examination shall be etched with 2% Nital. Micro Structure of the clip should reveal grain size ASTM-5 or finer with fully tempered martensite structure having no ferrite patches.
Minimum sample size required for the test shall be six. The sample clips of the decarburisation test and additional samples required to make up the number to six, depending upon the lot size, shall be taken up for testing for inclusion rating. The inclusion rating in the material of the clips when determined as per IS: 4163-1982 shall not be worse than 2.5 A,B,C,D both for thick and thin series given at Fig.2 of 18:4163-1982.
The sample clips shall be checked for the dimensions by means of inspection gauges as per RDSO drawings, and shall meet with requirement of dimensions and tolerances as provided in the drawings of inspection gauges.
The sample clips shall also be examined for the flat bearing lengths of the major & minor axis of toe of the clip with the rail flange in the rail seat assembly or in a fixture, which deflects the clip to the same extent as in the rail fastening assembly. For this purpose, the major and minor axis of the elliptical contact surface shall be measured to meet the requirements i.e. 28 mm X 9.5 mm. For ensuring that the flat toe bearing area of the toe of the clip with rail flange slope surface at the major and minor axis, a filer 0.05 mm thick shall not pass under the toe of clip along the major and minor axis of the clip.
Application and deflection test
The sample clips shall be tested by driving into a rail fastening assembly or in a fixture, which deflects the clip to the same extent as in the rail fastening assembly as approved by the purchaser. The clips shall then be removed from the fixture and checked for compliance with the dimension and tolerances.
Toe load test
The sample clips shall be checked for toe load, with the help of approved toe load test arrangement. Toe load values of the clips shall be within 1200 -1500 Kg.
After inspection and approval, the clips shall be cleaned off all rust and protected with one coat of boiled linseed oil as per 18:77-1976 or any other rust preventing compound approved by the purchaser.
The clips shall be packed in double gunny bags, each bag containing 50 clips. The packing shall be sound to ensure that there is no loss or damage to the clips during transit.
Disposal of rejected clips
The rejected clips shall be cut in two pieces using oxy-acetylene flame and shall then be disposed off as scrap.
Elastic Rail Clip for holding the rail with concrete sleeper comprising metal rod body having diameter of 23mm, central leg portion (DC) is reduced to 20.64mm for the length of 82mm to suit the existing concrete sleeper, junction (CB) of the different diameters is made in the form of taper portion, remaining portion (AB) of metal rod having diameter of 23 mm, toe portion of the clip having elli ptical shape of bottom of the metal rod to provide pressure on rail foot on larger area at deflected condition, heel portion opposite to toe of clip rests on plane surface of insert to take reaction from the said surface.
Elastic rail clips as claimed in claim 1 where in said central leg portion length and diameter as 82mm and 20.64mm respectively.
3. Elastic rail clip as claimed in claim 1 where in said elliptical shape of the toe portion of the clip is 35mm xl2mm in size.
4. Elastic rail clip as claimed in claim 1 where in said taper portion has length of 8mm.
5. Elastic rail clip as claimed in claim 1 where in said clip is configured to exert toe load in the range of 1200-1500 Kg at toe deflection of 13.5mm with extra margin of toe deflection up to 4-5mm without permanent deformation of the clip with stress induced of said deflection in the order of 129kg/mm2
6. Elastic rail clip as claimed in claim 1 where in said clip is used on the existing concrete sleeper track of railways with other existing fastening components.
7. Elastic rail clip for holding rail with sleeper as herein described with
reference to accompanying drawing.
|Indian Patent Application Number||726/DEL/2002|
|PG Journal Number||46/2010|
|Date of Filing||09-Jul-2002|
|Name of Patentee||RESEARCH DESIGN & STANDARDS ORGANISATION|
|Applicant Address||MINISTRY OF RAILWAYS, GOVT. OF INDIA, P.O. MANAK NAGAR, LUCKNOW-226001, U.P.|
|PCT International Classification Number||E01B 29/24|
|PCT International Application Number||N/A|
|PCT International Filing date|