Claims:We claim:
1) An apparatus (200) for measuring thickness of a tilting pad (100) of a bearing along a pivot line, said apparatus (200) comprising :
a) a magnetic V-block (202) provided with a ‘V’ shaped groove (G) at its center and a lever (L) for engaging or disengaging the magnetic field over said ‘V’ shaped groove (G);
b) a plurality of slip gauges (204) of varying thickness mounted on said ‘V’ shaped groove (G) of said magnetic V-block (202) to form a ‘V’ shaped provision (P1);
c) a plurality of spherical balls (206) of varying diameters mounted on said ‘V’ shaped provision (P1) of said plurality of slip gauges (204) and held firmly in position by engaging said lever (L) of said magnetic V-block (202);
d) a height gauge (210) comprising a holding arm (280) and a plurality of guide rods (282), said holding arm (280) adapted to couple to slide along said plurality of guide rods (282); and
e) a lever type dial gauge (208) comprising a measuring means (252), a contact probe (254), a dial (256), a pointer (258) and a bezel (260), said lever type dial gauge (208) adapted to couple to said holding arm (280) of said height gauge (210), said contact probe (254) of said lever type dial gauge (208) adapted to touch over a highest point of said plurality of spherical balls (206) and the reading of said height gauge (210) is recorded,

wherein the tilting pad (100) mounted over said plurality of spherical balls (206) and held firmly in position by means of a plurality of elastic bands (212) adapted to encompass said tilting pad (100) and said magnetic V-block (202), said contact probe (254) adapted to touch at a center point along said pivot line of said tilting pad (100) and the reading of said height gauge (210) is recorded, said contact probe (254) moved along said pivot line of said tilting pad (100) and the deviations of said pointer (258) in the dial (256) of said lever type dial gauge (208) are observed to assess whether the thickness of said tilting pad (100) is within tolerance limits or not.

2) An apparatus (200) for measuring thickness of a tilting pad (100) of a bearing along a pivot line as claimed in claim 1, wherein said plurality of slip gauges (204) act as support blocks for said plurality of spherical balls (206) in providing necessary height to mate with said tilting pad (100).

3) An apparatus (200) for measuring thickness of a tilting pad (100) of a bearing along a pivot line as claimed in claim 1, wherein said magnetic V-block (202) with said lever (L) in engaging position, facilitates in transferring the magnetic field to said plurality of slip gauges (204), said plurality of spherical balls (206) and said tilting pad (100).

4) An apparatus (200) for measuring thickness of a tilting pad (100) of a bearing along a pivot line as claimed in claim 1, wherein said plurality of spherical balls (206) of required diameter necessary to provide sufficient height to mate with the surface of said tilting pad (100) are available, the usage of said plurality of slip gauges (204) can be eliminated and said plurality of spherical balls (206) can be directly mounted on said ‘V’ shaped groove (G) of said magnetic V-block (202).

5) An apparatus (200) for measuring thickness of a tilting pad (100) of a bearing along a pivot line as claimed in claim 1, wherein the diameters of said plurality of spherical balls (206) and the sizes of said plurality of slip gauges (204) used in the apparatus (200) are selected depending on the dimensions of said tilting pad (100).

6) A method for measuring thickness of a tilting pad (100) of a bearing along a pivot line using an apparatus (200), said method comprising the steps of:
a) placing a plurality of slip gauges (204) on a ‘V’ shaped groove (G) of a magnetic V-block (202) forming a ‘V’ shaped provision (P1);
b) placing a plurality of spherical balls (206) on said ‘V’ shaped provision (P1) of said plurality of slip gauges (204) and held firmly in position by engaging a lever (L) of said magnetic V-block (202);
c) adapting to touch a contact probe (254) of a lever type dial gauge (208) over a highest point of said plurality of spherical balls (206) and noting down the reading of a height gauge (210);
d) mounting said tilting pad (100) over said plurality of spherical balls (206) and held firmly in position by means of a plurality of elastic bands (212) encompassing said tilting pad (100) and said magnetic V-block (202);
e) adapting to touch said contact probe (254) of said lever type dial gauge (208) at a center point along a pivot line of said tilting pad (100) and noting down the reading of said height gauge (210);
f) calculating the difference in the readings of said height gauge (210) from the step (e) and the step (c) to get the measured thickness of said tilting pad (100);
g) comparing the measured thickness of said tilting pad (100) with the designed thickness of said tilting pad (100) given by the manufacturer to find out whether the measured thickness is within tolerance limits or not, if yes, said tilting pad (100) is proceeded to further inspection, or else, rejected and replaced with new one; and
h) moving said contact probe (254) of said lever type dial gauge (208) along said pivot line of said tilting pad (100) and simultaneously observing the deviations of a pointer (258) of a dial (256) of said lever type dial gauge (208) to assess whether the measured thickness of said tilting pad (100) along said pivot line is within tolerance limits or not, if yes, said tilting pad (100) is accepted and proceeded to assembly, or else, rejected and replaced with new one.

7) A method for measuring thickness of a tilting pad (100) of a bearing along a pivot line using an apparatus (200) as claimed in claim 6, wherein perfect contact is achieved between said contact probe (254) and said tilting pad (100) along the pivot line while measurement.

, Description:FIELD OF THE INVENTION:
The present invention relates to the field of an apparatus and a method for measuring thickness of a tilting pad along a pivot line in cases where screw gauges of standard sizes won’t serve the purpose. Particularly, the present invention relates to an apparatus and a method of measuring thickness of a tilting pad along a pivot line accurately which in turn helps in calculating the bearing clearance accurately.

BACKGROUND OF THE INVENTION:
Generally, rotating machinery like turbines, compressors, pumps, generators etc., are supported on oil film bearings. Bearing clearance is an important aspect in smooth operation of any turbo machinery. The journal bearings of a turbo machine are subjected to high dynamic loads during operation which results in deformation or wear and tear of tilting pads of the bearings which ultimately results in generation of sub synchronous vibrations due to oil whirl. So, it is a crucial task in refurbishment of turbines to retain tilting pads in good condition or replace worn out tilting pads with new ones for efficient operation of the turbine and thereby maintaining bearing clearances as per the design requirement.

Typically, tilting pads of journal bearings are manufactured in different sizes depending on the diameter of a rotor of a turbine and the screw gauges of standard sizes available in the market are not in a position to measure the thickness of the tilting pads.

Figure 1 illustrates an isometric view of a tilting pad of a journal bearing.
The tilting pad 100 of a journal bearing resembles the shape of a secant cut from a cylinder. The tilting pad 100 is provided with a projection P at its center which facilitates in forming an axial line pivot when in contact with bearing housing.

Figure 2 illustrates a conventional method of measuring thickness of a tilting pad.
The conventional method of measuring thickness of a tilting pad 100 is done by using a screw gauge 150. The thickness of the tilting pad 100 as shown in the figure 2 typically varies between 30mm to 40mm. With the help of standard size screw gauge 150 available in the market which can measure thickness between 25mm to 50mm, we can measure thickness of the tilting pad 100 only at its extreme ends but not at its center as frame F of the screw gauge 150 is obstructed by the side face of the tilting pad 100.

Typically, the screw gauges customized for measuring thickness of a titling pad 100 of a bearing also won’t maintain proper point of contact along a pivot line and won’t measure thickness of a tilting pad 100 along a pivot line accurately.

Typically, the method of measuring thickness of a tilting pad 100 of a bearing along a pivot line using customized screw gauges is laborious, requires skilled operators and not foolproof.

Several techniques have been disclosed in the prior art for measuring dimensions of the objects using unconventional measuring instruments.

US Patent no. 5640778 filed on November 15th, 1995 titled “Apparatus and a Method for measuring the curvature radii of spherical and cylindrical surfaces” discloses an apparatus comprising a base, a probe, and four ball rings of the equal size, wherein the four ball rings are provided on the base and arranged in to a square having a side length C. The probe is upward and downward movably mounted on the top surface of the base at the center of the square. The granted invention discloses a method of measuring the curvature radii of spherical and cylindrical surfaces using trigonometric functions. The granted patent teaches about the method of measuring the curvature radii of spherical and cylindrical surfaces but the granted patent is silent on measuring the thickness of spherical and cylindrical surfaces.

EP Patent no. 0904136 filed on April 16th, 1997 titled “Ball Controller for checking the diameter of a golf ball” discloses a ball controller or so called calibrator in the form of a rigid mat having a central cavity for the reception of a golf ball, the ball controller having sectionally differing wall thicknesses in the radial direction of the controller and preferably having an optimal thickness in a radially inner most, annular portion around the cavity. The cavity has a cylindrical inner face having an axial dimension of 3mm minimum. The granted patent illustrates an apparatus specifically designed for checking the diameter of the golf balls at the golf course accurately instead of using an expensive apparatus available at manufacturer’s end.

US Patent no. 6578281 filed on June 15th, 2001 titled “Apparatus and Method for measuring spherical article” discloses a measuring apparatus comprising a first support arm, a second support arm and a size detector. The first support arm has first and second ends. The first end can be brought in contact with a first curve section of a spherical article to be measured at one end of the diametrical line in the spherical article. The second end can be located spaced apart from and opposite to a second curve section of the spherical article at the other end of the diametrical line. The second support arm has a third end which can be brought in contact with a third curve section of the spherical article. The size detector can be brought in contact with the second curve section and thereby checking whether the diameter of the spherical article is within the permissible limits or not. The granted patent teaches an alternative and inexpensive method of measuring the diameter of the spherical articles like ten-pin bowling balls, billiard balls, volleyball balls and soccer balls at the playground instead of using an expensive apparatus available at manufacturer’s end.

Therefore, there is felt a need for development of a new apparatus and a method for measuring the thickness of a tilting pad of a bearing along a pivot line during refurbishment of a turbo machine to overcome the drawbacks of the prior art and thereby finally overcoming the necessity to purchase an expensive and specifically designed apparatus.

OBJECTS OF THE INVENTION:
An object of the present invention is to provide a simple and easy apparatus for measuring the thickness of a tilting pad of a bearing along a pivot line during refurbishment of a turbo machine.

Another object of the present invention is to provide an inexpensive apparatus for measuring the thickness of a tilting pad of a bearing along a pivot line during refurbishment of a turbo machine.

One more object of the present invention is to provide an apparatus and a method to measure whether thickness of a tilting pad of a bearing along a pivot line is within tolerance limits or not during refurbishment.

Still another object of the present invention is to provide an apparatus to measure tilting pads of varying thickness.

Further another object of the present invention is to provide a foolproof apparatus and a method to measure thickness of a tilting pad of a bearing along a pivot line accurately with the help of semi skilled labour also.

Yet another object of the present invention is to provide an apparatus which will maintain proper point of contact along a pivot line of a tilting pad of a bearing while measuring.

SUMMARY OF THE INVENTION:
In accordance with the present invention an apparatus (200) for measuring thickness of a tilting pad (100) of a bearing along a pivot line is provided, the apparatus (200) comprising:

(i) a magnetic V-block (202) provided with a ‘V’ shaped groove (G) at its center and a lever (L) for engaging or disengaging the magnetic field over the ‘V’ shaped groove (G);
(ii) a plurality of slip gauges (204) of varying thickness mounted on the ‘V’ shaped groove (G) of the magnetic V-block (202) to form a ‘V’ shaped provision (P1);
(iii) a plurality of spherical balls (206) of varying diameters mounted on the ‘V’ shaped provision (P1) of the plurality of slip gauges (204) and held firmly in position by engaging the lever (L) of the magnetic V-block (202);
(iv) a height gauge (210) comprising a holding arm (280) and a plurality of guide rods (282), the holding arm (280) adapted to couple to slide along the plurality of guide rods (282); and
(v) a lever type dial gauge (208) comprising a measuring means (252), a contact probe (254), a dial (256), a pointer (258) and a bezel (260), the lever type dial gauge (208) adapted to couple to the holding arm (280) of the height gauge (210), the contact probe (254) of the lever type dial gauge (208) adapted to touch over a highest point of the plurality of spherical balls (206) and the reading of the height gauge (210) is recorded,

wherein the tilting pad (100) mounted over the plurality of spherical balls (206) and held firmly in position by means of a plurality of elastic bands (212) adapted to encompass the tilting pad (100) and the magnetic V-block (202), the contact probe (254) adapted to touch at a center point along the pivot line of the tilting pad (100) and the reading of the height gauge (201) is recorded, the contact probe (254) moved along the pivot line of the tilting pad (100) and the deviations of the pointer (258) in the dial (256) of the lever type dial gauge (208) are observed to assess whether the thickness of the tilting pad (100) is within tolerance limits or not.

Typically, the diameters of the plurality of spherical balls (206) and the sizes of the plurality of slip gauges (204) used in the apparatus (200) are selected depending on the dimensions of the tilting pad (100).

In accordance with the present invention a method for measuring thickness of a tilting pad (100) of a bearing along a pivot line using an apparatus (200) is provided, the method comprising the steps of:
(i) placing a plurality of slip gauges (204) on a ‘V’ shaped groove (G) of a magnetic V-block (202) forming a ‘V’ shaped provision (P1) ;
(ii) placing a plurality of spherical balls (206) on the ‘V’ shaped provision (P1) of the plurality of slip gauges (204) and held firmly in position by engaging a lever (L) of the magnetic V-block (202) ;
(iii) adapting to touch a contact probe (254) of a lever type dial gauge (208) over a highest point of the plurality of spherical balls (206) and noting down the reading of a height gauge (210) ;
(iv) mounting the tilting pad (100) over the plurality of spherical balls (206) and held firmly in position by means of a plurality of elastic bands (212) encompassing the tilting pad (100) and the magnetic V-block (202) ;
(v) adapting to touch the contact probe (254) of the lever type dial gauge (208) at a center point along a pivot line of the tilting pad (100) and noting down the reading of the height gauge (210) ;
(vi) calculating the difference in the readings of the height gauge (210) from the step (v) and the step (iii) to get the measured thickness of the tilting pad (100) ;
(vii) comparing the measured thickness of the tilting pad (100) with the designed thickness of the tilting pad (100) given by the manufacturer to find out whether the measured thickness is within tolerance limits or not, if yes, the tilting pad (100) is proceeded to further inspection, or else, rejected and replaced with new one ; and
(viii) moving the contact probe (254) of the lever type dial gauge (208) along the pivot line of the tilting pad (100) and simultaneously observing the deviations of a pointer (258) of a dial (256) of the lever type dial gauge (208) to assess whether the measured thickness of the tilting pad (100) along the pivot line is within tolerance limits or not, if yes, the tilting pad (100) is accepted and proceeded to assembly, or else, rejected and replaced with new one.

Typically, perfect contact is achieved between the contact probe (254) and the tilting pad (100) along the pivot line while measurement.

BRIEF DESCRIPTION OF THE DRAWINGS:
The invention will now be described with reference to the accompanying drawings in which:
Figure 1 illustrates an isometric view of a tilting pad of a journal bearing;

Figure 2 illustrates a conventional method of measuring thickness of a tilting pad according to the prior art; and

Figure 3 illustrates a perspective view of an apparatus for measuring thickness of a tilting pad of a bearing along a pivot line in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS:
A preferred embodiment will now be described in detail with reference to accompanying drawings. The preferred embodiment does not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.

Figure 3 illustrates a perspective view of an apparatus for measuring thickness of a tilting pad of a bearing along a pivot line.

In accordance with the present invention, there is provided an apparatus 200 for measuring thickness of a tilting pad 100 of a bearing along a pivot line comprising a magnetic V-block 202, a plurality of slip gauges 204, a plurality of spherical balls 206, a lever type dial gauge 208, a height gauge 210 and a plurality of elastic bands 212.

The magnetic V-block 202 is a rectangular block provided with a ‘V’ shaped groove G at its center. The ‘V’ shaped groove G can be activated with magnetic field or deactivated from magnetic field with the help of engaging or disengaging lever L.

The plurality of slip gauges 204 are rectangular blocks of varying thickness.

The plurality of spherical balls 206 are balls of varying diameters.

The lever type dial gauge 208 includes a measuring means 252, a contact probe 254, a dial 256, a pointer 258 and a bezel 260. The measuring means 252 is provided with a pivot at one end and a dial 256 at other end. The contact probe 254 is coupled to the pivot of the measuring means 252 free in rotation. The pointer 258 is adapted to couple over the dial 256 free in rotation. The bezel 260 is adapted to encompass and coupled to the dial 256 in free rotation.

The height gauge 210 comprises a holding arm 280 and a plurality of guide rods 282. The holding arm 280 is adapted to couple to slide along the plurality of guide rods 282.

The lever type dial gauge 208 is adapted to couple to the holding arm 280 of the height gauge 210.

Typically, the plurality of slip gauges 204 supports the plurality of spherical balls 206 and provides the necessary height for the spherical balls 206 to mate with the surface of the tilting pad 100.

The configuration and method of working of an apparatus 200 for measurement of the thickness of the tilting pad 100 of a bearing along a pivot line in accordance with the present invention is as follows:

Firstly, the lever L of the magnetic V-block 202 is kept in disengaging position such that the magnetic field is not present on the ‘V’ shaped groove G. Secondly, the plurality of slip gauges 204 are placed over the ‘V’shaped groove G of the magnetic V-block 202 forming a V shaped provision P1 for accommodating the plurality of spherical balls 206. Thirdly, the plurality of spherical balls 206 are placed at extreme ends of the plurality of slip gauges 204 and simultaneously the lever L of the magnetic V-block 202 is turned to engaging position such that the spherical balls 206
are held in position firmly over the V shaped provision P1 of the slip gauges 204 due to transfer of magnetic field from the slip gauges 204. Fourthly, the contact probe 254 of the lever type dial gauge 208 is adapted to touch over a highest point of the spherical ball 206 and the reading of the height gauge 210 is noted down. Fifthly, the tilting pad 100 of a bearing is placed over the plurality of spherical balls 206 and the weight of the tilting pad 100 tries to move the spherical balls 206 which in turn tries to move the slip gauges 204 but the movement of the spherical balls 206 and the slip gauges 204 is arrested due to transfer of magnetic field from the magnetic V-block 202. Sixthly, the tilting pad 100 is held firmly in contact with the surface of the spherical balls 206 by means of the plurality of elastic bands 212 adapted to encompass the tilting pad 100 and the magnetic V-block 202. Seventhly, the contact probe 254 of the lever type dial gauge 208 is adapted to touch at a center point along a pivot line of the tilting pad 100 of a bearing and the reading of the height gauge 210 is noted down. The difference in the readings of the height gauge 210 from the seventh step and the fourth step gives the thickness of the tilting pad 100 of a bearing. The measured thickness of the tilting pad 100 is compared with the designed thickness of the tilting pad 100 given by the manufacturer to ensure whether the thickness of the tilting pad 100 is within tolerance limits or not. If the measured thickness of the tilting pad 100 at the center point is within tolerance limits, it is subjected to further inspection or else, rejected and replaced with new one. Finally, if the measured thickness of the tilting pad 100 at the center point is within tolerance limits, the contact probe 254 in contact with the tilting pad 100 is moved along the pivot line and the deviations of the pointer 258 in the dial 256 are observed, if the deviations of the pointer 258 in the dial 256 are within tolerance limits, the tilting pad 100 is accepted and pass on to the assembly or else, rejected and replaced with new one.

Typically, if the spherical balls 206 of required diameter necessary to provide sufficient height to mate with the surface of the tilting pad 100 are available, the usage of the slip gauges 204 can be eliminated and the spherical balls 206 can be directly mounted on the ‘V’ shaped groove G of the magnetic V-block 202.

Typically, the diameters of the spherical balls 206 and the sizes of the slip gauges 204 used in the apparatus 200 are selected depending on the dimensions of the tilting pad 100.

TECHNICAL ADVANCEMENTS:
An apparatus for measuring thickness of a tilting pad of a bearing along a pivot line and a method thereof has several technical advantages including but not limited to the realization of:
• a simple and easy apparatus for measuring the thickness of a tilting pad of a bearing along a pivot line during refurbishment of a turbo machine;
• an inexpensive apparatus for measuring the thickness of a tilting pad of a bearing along a pivot line during refurbishment of a turbo machine;
• an apparatus and a method to measure whether thickness of a tilting pad of a bearing along a pivot line is within tolerance limits or not during refurbishment;
• an apparatus to measure tilting pads of varying thickness;
• an apparatus which will maintain proper point of contact along a pivot line of a tilting pad of a bearing while measuring; and
• a foolproof apparatus and a method to measure thickness of a tilting pad of a bearing along a pivot line accurately with the help of semi skilled labour also.

Although the invention has been described herein above with reference to the embodiments of the invention, the invention is not limited to the embodiments described herein above. It is to be understood that modifications and variations of the embodiments can be made without departing from the spirit and scope of the invention.