FORM 2
THE PATENT ACT 1970
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"Bearing Spacer"
2. APPLICANT
(a) NAME: Innoventive Industries Ltd
(b) NATIONALITY: Indian Company
(c) ADDRESS: Gat No. 1261, Sanaswadi,
Pune Nagar Raod, Tal.- Shirur, Dist. - Pune 412208 MS India
3. PRREAMBLE TO THE DESCRIPTION
COMPLETE
The following specification particularly describes the invention and the manner in which it is to be performed.

Bearing Spacer
FielcTof the Invention
The present invention relates to a method for production spacer, more particularly, to a bearing spacer or wheel spacers, made out of a cold drawn electric resistance welded (CEW) tube/a drawn over mandrel (DOM) tube.
Background of the Invention
Bearing Spacers or Wheel Spacers are used to maintain a specific distance in between bearings on wheel axles, in commercial passenger vehicles. Earlier these spacers were made from solid bars. Thereafter, these spacers are manufactured from castings/forgings wherein machining is a critical factor.
These spacers are assembled with wheel axle bearings. These assemblies had problems due to various casting/forging/solid bar defects and also high cost of manufacturing.
Objects of the Invention
Object of the present invention is to provide low cost bearing spacers.
Another object of the present invention is to provide a bearing spacer, which eliminates defects caused due to casting/forging/solid bar processes,
Summary of the invention
Accordingly, the present invention provides a method for production of a bearing spacer manufactured using a CEW / DOM tubes. The method of production of the

bearing spacer comprises of the following steps namely cutting of the CEW/DOM tube on a band saw to determine the predefined length of a plurality of pieces further subjected to facing on a lathe machining tool, profiled conical using a hydraulic press, faced and chamfered on CNC machine and finally checked for quality assurance before final packaging.
Detailed Description of the Invention
The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiments.
The bearing spacer of the present intention is a cold drawn electric resistance welded tube (herein after the 'CEW') /drawn over mandrel (herein after the 'DOM') tube. The CEW / DOM tube is made up of a ferrous material preferably steel with desired mechanical and chemical properties. It is however understood that the CEW / DOM tube can also be made up of a ferrous material or a non-ferrous materia] as per the requirement. The CEW / DOM tubes are subjected to rolling (forming / welding / sizing) on the basis of the requirement and characteristic of the end product.
The present invention provides a method for manufacturing of bearing spacers using the CEW/DOM tube. In this preferred embodiment, the CEW / DOM tube is steel material. The diameter and width of the CEW / DOM tube is selected as per the requirement of the bearing size, make, and number of ball bearing used, and the like. The diameter and width of the tube bears a direct proportionality to the size of the bearing. It is however understood that diameter and length of the tube can be variably selected as per the product specification.
In the preferred embodiment, the CEW / DOM tube is required to be pre-treated. The pre-treating step includes initial heating of the CEW / DOM tube, followed by swaging of the heated tube, and finally drawing the swaged CEW / DOM tube

cold. The pre-treatment of the CEW / DOM tube is performed for the forming required after cutting to get shapes of bearing spacer.
The pre-treatment includes subjecting the CEW / DOM tube to heat treatment such that the CEW / DOM tube is heated preferably in the range of 750°C to 950°C (degree Celsius) in roller hearth furnace (RHF). Thereafter, the heated CEW / DOM tube is subjected to swaging.
The swaging of the tube end is done for drawing purpose. The drawing process is a cold process carried out in the temperature range of 50°C to 200°C and pressure 5 to 7 kg /cm2. The swaged CEW / DOM tube in the preferred embodiment is drawn cold in piiger / draw bench.
The pre-treated CEW / DOM tube is subjected to test for defects like cracks using eddy current method. Pre-treated CEW / DOM tube is also subjected for various tests like hardness, flaring, flattening, crushing, yield strength, tensile strength, percent (%) elongation to determine mechanical and chemical properties. Inspection for dimensional and visual characteristics of pre-treated CEW / DOM tube is further carried to assure the final quality required for the end product, i. e. bearing spacer.
The pre-treated CEW/DOM tube is then subjected for cutting the. In an embodiment, the cutting is carried out using a band saw. The cutting of the CEW / DOM tube results in a plurality of pieces of a predefined length. The length of the cut pieces is selected with respect to the length of bearing spacer to be manufactured.
The cut pieces of the CEW / DOM tube are then subjected to end facing on a lathe machining tool to even/smoothen the cut pieces surface obtained from the earlier step.
The faced pieces the CEW / DOM tube are pressed in a hydraulic press to form a desired profile of the bearing spacers. In the preferred embodiment, the profiling is preferably conical in shape. It is however understood that profiling shape may

vary as per the product requirement. The forming tool is designed in accordance with the desired profile.
The profiled CEW / DOM tube are then subjected for finishing operations on a numerical control machining tool. In this preferred embodiment, the finishing operations are performed on a computer numerical control (CNC). CNC machining is done on part of inner diameter and end faces.
Finally, the machined pieces are inspected for quality assurance. The machined pieces are subjected to dimensional checking and visual checking. UTM test is performed on the machined pieces for process qualification. Quality approved machined pieces are used as the finished bearing spacer for packaging.
EXAMPLES
EXAMPLE-: Chemical Analysis of the CEW / DOM tube The pre-treated CEW / DOM tube used in the preferred method for the production of bearing spacer of the present invention was tested to analyze and ascertain that the chemical components are within prescribed limit. Accordingly, the CEW / DOM tube, having an outer diameter of 83.00 mm, an inner diameter of 75.00 mm and a length of 4.15 meters, was taken for the chemical analysis.
Table I: Chemical analysis data

Chemical %C %Mn %Si %S %P %Nb %V %AI
components
Specification
(Max.) 0.22 1.6 0.55 0.025 0.025 — ~ ~
Specification
(Observed) 0.165 1.270 0.090 0.0040 0.0130 — — 0.0450

It was observed that, the pre-treated CEW / DOM tube used in the preferred method for bearing spacer production of the present invention was having observed specification well below the maximum specification limits. Accordingly, the chemical component stability of the CEW / DOM tube was ascertained
EXAMPLE-: Dimensional Analysis of the CEW / DOM tube
The pre-treated CEW / DOM tube used in the preferred method for the production of bearing spacer of the present invention was analyzed to ascertain that the dimensional components of the CEW / DOM tube were within prescribed limit. Accordingly, the pre-treated CEW / DOM tube, having an outer diameter of 83.00 mm, an inner diameter of 75.00 mm and a length of 4.15 meters, was taken for dimensional observations.
Table 2: Dimensional analysis data

Dimensional observations Outer Dia. (mm) Wall Thickness (mm) Inner Dia. (mm) Length (mm)
Spec. Min. 82.80 — 75.05 —

Max. 82.95 — 75.20 ——
Spec. ( 'Observed) 82.86 -82.90 75.09-75.14 4150.00
It was observed that, the pre-treated CEW / DOM tube used in the preferred method for the production of bearing spacer of the present invention was having observed specification well within the minimum-maximum specification limits. Accordingly, the dimensional stability of the CEW / DOM tube was ascertained
EXAMPLE-: NDT / ECT testing of the CEW / DOM tube

The pre-treated CEW / DOM tube used in the preferred method for the production of bearing spacer of the present invention was tested for non destructive testing (NUT)/ eddy current testing (ECT). Accordingly, the pre-treated CEW / DOM tube, having an outer diameter of 83.00 mm, an inner diameter of 75.00 mm and a length of 4.15 meters, was taken for the testing. Accordingly, various tests such as Hardness, Flaring Test, Flattening Test, Crushing Test, Yield Strength, Tensile strength and % Elongation were carried out.
Table 2: Mechanical properties data

Mech. Hardness Flaring Flatten in Crushing Yield Tensile %
Properties (HRB) Test g Test Strength Strength Elongat
Test Kg/mm2 Kg/mm2 ion
Specified 95 (Min.) (25%OD) (1/20D) Test — 640 4%
Values Min. Min. (25%) (Min.) (Min.)
Observed
Values 97/98 OK OK OK 570.35 649.19 19.10
It was observed that, the tube undergone 100% NDT (ECT) testing and conforms to the standard.
The bearing spacer prepared by the process of the present invention has advantages of providing longer life to the bearing spacer. Further, the bearing spacer prepared by the process of the present invention eliminates defects caused due to casting / forging / solid bar processes and is economical to manufacture.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We claim,
1. A method for production of bearing spacers using a cold drawn electric
resistance welded (CEW) tube/a drawn over mandrel (DOM) tube,
comprising:
pre-treating the CEW/DOM tube, wherein pre-treating step comprises,
heating the CEW/DOM tube,
swaging the heated CEW/DOM tube, and
cold drawing the swaged tube;
cutting the pre-treated CEW/DOM tube in to a plurality of pieces of predefined length;
facing the plurality of cut pieces using a lathe machining tool;
profiling the faced pieces using a hydraulic press;
facing and chamfering of the profiled pieces on a numerical control machine; and
subjecting the chamfered pieces to quality check.
2. The method for production of the bearing spacers as claimed in claim 1, wherein the heat pre-treatment of the CEW / DOM tube is carried out in the temperature range of 750°C to 950°C.
3. The method for production of the bearing spacers as claimed in claim 1, wherein swaging of the tube end is done for drawing purpose.
4. The method for production of the bearing spacers as claimed in claim 1, wherein the drawing process is a cold process carried out in a temperature range of 50°C to 200°C and a pressure range of 5 to 7 kg /cm2.

5. The method for production of the bearing spacers as claimed in claim 1, wherein the CEW/ DOM tube is cut in pieces at a predefined length using a band saw.
6. The method for production of the bearing spacers as claimed in claim 1. wherein the length of the cut pieces is selected with respect to the length of the bearing spacer to be manufactured.
7. The method for production of the bearing spacer as claimed in claim 1, wherein the profiling of the cut pieces of the CEW/ DOM tube is done in conical shape.
8. The method for production of the bearing spacers as claimed in claim 1, wherein the numerical control machine used for facing and chamfering of the profiled pieces is a computer numerical control (CNC) machine.