FIELD OF INVENTION
The present invention relates to the development of a manual measuring device to
measure all the critical linear and taper dimensions of 3DS & F Z -shroud blades of
steam turbine as an alternative to 3D CMM. More particularly, the manual measuring
device measures all the critical linear and taper dimensions of 3 DS and F Z shroud
blades of steam turbines more easily and accurately in a simple way.
BACK GROUND OF THE INVENTION
In a machine shop having 26 nos. of 5-axis machines (consisting of 9 nos. single
spindle, 9 nos. double spindle & 8 no§. triple spindle machine) on which 3DS and F
blades of steam turbine are getting manufactured from the different rectangular bar
having different cross-sections. The design & shape of 3DS & F Z-shroud blades are
complicated and these blades are manufactured in a single spindle 5-axis machines. It
is very difficult to measure the dimension of Z-shroud blades manually. Some very
critical dimensions are to be controlled from the axis of blade which cannot be
measured manually. These dimensions are to be checked in 3D CMM only. No alternate
method was available in case of non availability of 3D CMM.
First of all, these blanks are cut into the desired length including the extra length
including allowances for clamping/ holding of blank inside the machines for machining.
During generation of technological allowances in the blank, centre holes are being
made at both ends of blank in the middle which is taken as reference inside the

machine during the blade machining as a blade axis. After machine of blades on 5-axis
machines, these technological allowances are removed by milling operation after
checking the dimensions of blade in 3D CMM. And then the subsequent finishing
processes are carried out on the blades.
After 5-axis machining, when the blades are sent for checking in 3D CMM all normal
dimensions, critical dimensions from the axis of blade and angles are checked and a
report get generated. And on the basis of 3D CMM report of blade the manufacturing of
further blades continues.
In case of the malfunctioning of the measuring machine or non availability of the
machine the production is held up. The situation is overcome by the invention of the
invented measuring device. Though, the linear dimension can be measured manually by
Proper Measuring Instrument but the critical dimension like angles, taper dimension and
controlled dimension from the blades axis cannot be measured manually.
Therefore it was needed to develop a system to measure some critical dimension of
steam turbine Z-shroud blades manually as an alternate of 3D CMM in case of any
emergency.
OBJECT OF INVENTION
The object of the invention is to develop a manual device to measure some critical
dimensions of 3DS & F Z-shroud of Steam Turbine as an alternative of 3D CMM more
easily and accurately in a simple way.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWING
Fig. 1:- Detailed sketch drawing of Fixture on which the Z-shroud blades to be clamped
horizontally.
Fig. 2:- Sketch drawing of Fixture along with Height Gauge on surface plate on which
the Z-shroud blade to be checked.
Fig. 3:- Detailed sketch drawing of Z-shroud blade to show critical dimensions.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
In 3D CMM, first the axis of blade is being generated by taking reference from
reference planes of the blade then all linear, taper & critical dimensions like half pitch,
full pitch, angles etc are get measured on the basis of blade axis generated in the
beginning.
To check linear dimension manually, it can be done by using proper measuring
instrument. But for checking critical dimension like half pitch, full pitch, dimensions from
blade axis etc, a height gauge is required with proper Dial Gauge and on other hand the
blade is to be kept horizontally to maintain the blade axis parallel to base where height
gauge is kept.
The blade axis is to be defined first and the height gauge will measure all critical
dimensions of blade by taking zero reference from blade axis. In this case, all the linear
and taper dimensions including half pitch and full pitch dimensions from the blade axis
can be measured.
The device keeps the blade axis horizontally parallel to base (Surface Plate) where
height gauge is kept. The centre holes at both ends of blade can be used for keeping
the blade axis horizontally by putting male centres at both end of blade and the height

gauge can take reference from these two male centres only to measure all critical
dimensions.
New device has been made to clamp blade horizontally by putting one fixed male centre
and second sliding male centres at both ends which will be fixed in the centre holes of
Z-shroud blade at both ends. All the parts of the device are made of steel and the
centres are hardened.

Reference Numerals used:
01-Fixed column
02-Sliding column
03-Work piece adaptor
04-Tips of male centres for clamping of inner blade
05- Support for resting of blade
06-Base frame of the device
07-Guide ways for sliding column
08-Fixed Male centre
09-Sliding male centre
10- Turbine blade
11-Vernier height gauge
12-Handle

WE CLAIM
1. A device to measure the critical dimension of 3 DS and FZ shroud blade of steam
turbine comprising :
a fixed column (01) erected vertically on base (6);
a guide way (7) on base (6);
a moveable vertical sliding column (2) disposed such that it can slide on the guide
way (7) forward and backward;
a fixed male centre (8) disposed on fixed column (01) and sliding male centre (09)
disposed on sliding column (2) such that the pointed male centres (04, 04) are
horizontal and parallel to the base (6)
a work piece adopter (03) with a support (05) for resting of blade (10) disposed on
the fixed column characterized in that the male centres tips (04, 04) fit into the
centre holes of the F Z-shroud blade horizontally where the fixed male centre (8)
and sliding male centre (09) grips the blade properly and horizontally by to and fro
movement of the sliding male centre (09) on adjustable sliding column (2).
2. The device as claimed in claim 1 wherein the fixed (8) and sliding male centre
(09) are equipped with the handle (12).
3. The device as claimed in claim 1 are made of steel and the centres are
hardened.

4. The device as claimed in claim 1 wherein the sliding column (2) can slide on the
guide way (7) freely and the sliding male centre (09) can move forward and
backward within the hole equipped on sliding column (02).
5. The device as claimed in claim 1 where the height gauge record measurements
through dial gauge equipped on it.

ABSTRACT

A device to measure the critical dimension of 3 DS and FZ shroud blade of steam
turbine comprising :
a fixed column (01) erected vertically on base (6);
a guide way (7) on base (6);
a moveable vertical sliding column (2) disposed such that it can slide on the guide
way (7) forward and backward;
a fixed male centre (8) disposed on fixed column (01) and sliding male centre (09)
disposed on sliding column (2) such that the pointed male centres (04, 04) are
horizontal and parallel to the base (6)
a work piece adopter (03) with a support (05) for resting of blade (10) disposed on
the fixed column characterized in that the male centres tips (04, 04) fit into the
centre holes of the F Z-shroud blade horizontally where the fixed male centre (8)
and sliding male centre (09) grips the blade properly and horizontally by to and fro
movement of the sliding male centre (09) on adjustable sliding column (2).